Enfortumab vedotin and pembrolizumab: redefining the standard of care for previously untreated advanced urothelial cancer

ABSTRACT

Combination treatment with Enfortumab vedotin (EV), an antibody drug conjugate targeting Nectin-4 with a monomethyl auristatin E (MMAE) payload, and pembrolizumab, a programmed death 1 (PD-1) inhibitor, has become the new standard of care for previously untreated locally advanced or metastatic urothelial carcinoma. In the recently published phase III study, EV-302, EV and pembrolizumab demonstrated improved outcomes compared to platinum-based chemotherapy, including objective response rate, progression free survival, and an unprecedented median overall survival of 33.8 months (versus 15.9 months; hazard ratio for death 0.51; 95% confidence interval 0.43–0.61; p < 0.00001). We reviewed the mechanism of action, clinical efficacy, exploratory biomarkers, and safety profile of EV and pembrolizumab as monotherapies and combination in urothelial cancer.

Plain Language Summary

What is this article about?

This review provides information about the use of a new combination of two drugs- enfortumab vedotin (EV) and pembrolizumab, in the treatment of metastatic urothelial cancer.

What have studies shown?

Both EV and pembrolizumab have previously individually shown to be effective in bladder cancer after other treatments have failed. In a large study including 886 patients, the new combination of EV and pembrolizumab was compared to the standard chemotherapy as the first treatment in patients with bladder cancer. Patients treated with EV and pembrolizumab lived longer and had a longer time without cancer progression compared to patients treated with chemotherapy. Patients treated with EV and pembrolizumab were more likely to have meaningful tumor shrinkage: in 30.4% the tumors were no longer detected on imaging scans compared to 14.5% with chemotherapy. Serious side effects can occur with the new treatment including rash, nerve damage, high blood sugar, and lung inflammation.

What conclusions can be made from these studies?

The combination of enfortumab vedotin and pembrolizumab is the new recommended treatment for locally advanced and metastatic urothelial cancer.

1. Introduction

Urothelial cancer (UC) is the ninth most frequently diagnosed malignancy worldwide, with an estimated 84,870 new cases and 17,420 deaths from urothelial cancer in the U.S. alone in 2025 [1–3]. Risk factors for UC include older age (median age at diagnosis is 73 years), male sex and smoking history, as well as various occupational exposures and genetic factors. UC most commonly develops in the urinary bladder comprising > 90% of bladder tumors, but can also arise in the ureter, renal pelvis, or the urethra.

Locally advanced or metastatic urothelial cancer (la/mUC) is associated with poor prognosis and 5 years overall survival (OS) <10% [2]. For decades, cisplatin-based chemotherapy remained the standard of care in the first-line setting, resulting in median overall survival (mOS) of 14 to 15 months [4]. Approximately half of the patients are ineligible for cisplatin [5,6], and were treated with carboplatin-based chemotherapy with even less favorable results and mOS of 9 to 10 months [7,8]. Maintenance avelumab has been shown to prolong OS compared with best supportive care (HR 0.78, 95% confidence interval [CI] 0.63–0.91, p-0.0036), but is only indicated for patients free of progression on platinum based chemotherapy [9,10]. Previous studies evaluating combination of platinum-based chemotherapy and immune checkpoint inhibitors (CPI) as first-line treatment did not show improvement in OS [11,12]. More recently, the combination of cisplatin, gemcitabine, and nivolumab followed by nivolumab did result in improved outcomes compared to cisplatin and gemcitabine alone, with mOS of 21.7 months (HR 0.78, 95% CI 0.63–0.96, p-0.02) [13].

Enfortumab vedotin (EV), an antibody-drug conjugate targeting Nectin-4, and pembrolizumab, a programmed death 1 (PD-1) inhibitor, individually showed OS benefit in pretreated patients with la/mUC. Based on preclinical data suggesting enhanced and durable antitumoral activity, the combination of EV and pembrolizumab (EV/P) initially emerged as a promising first-line alternative for cisplatin ineligible patients with a response rate of 73.3% and 64.5% in two phase 2 cohorts [14,15]. This combination has now become the new standard of care regardless of cisplatin eligibility following the striking results of the phase III EV 302 study including an unprecedented landmark mOS of 33.8 months [16,17]. Herein, we review the preclinical data and published clinical trials, summarizing the biological background, rationale, clinical efficacy, and safety data for EV, pembrolizumab, and the combination in metastatic urothelial carcinoma.

2. Enfortumab vedotin for urothelial cancer

2.1. Mechanism of action and pharmacology

EV is an antibody-drug conjugate (ADC) composed of an anti-Nectin-4 fully human immunoglobulin G1 kappa monoclonal antibody conjugated via a protease-cleavable linker to monomethyl auristatin E (MMAE), a microtubule-disrupting agent, with a drug:antibody ratio (DAR) of 3.8. Nectin-4 is a transmembrane cell adhesion protein over-expressed in urothelial carcinoma. Binding of EV to target cells triggers internalization and selective release of MMAE [18,19]. EV has also demonstrated bystander effect in an admixed cellular assay, by release of cell permeable MMAE from Nectin-4 positive cells to affect Nectin-4 negative cells [20].

EV is administered intravenously over 30 minutes at 1.25 mg/kg up to a maximal dose of 125 mg. As monotherapy, EV is given on days 1, 8, and 15 of a 28-day cycle. Optimal dose was determined based on data from the phase I dose escalation EV-101 [21] showing linear pharmacokinetics (PK) over a dose range of 0.5–1.25 mg/kg with higher efficacy at the 1.25 mg/kg dose level. Recently presented exploratory analysis of the EV monotherapy phase I/II/III studies showed greater probability of response with higher early dose intensity measured in the first 2 cycles [22]. Peak ADC and free MMAE (fMMAE) concentrations are achieved at the end of the infusion and after approximately 2 days, respectively, with minimal accumulation of both upon repeat dosing. At 1.25 mg/kg dose level, the ADC elimination half-life is approximately 3.6 days; the fMMAE elimination half-life is 2.6 days and the elimination rate appears to be limited by release from the ADC [23]. The metabolism of EV has been studied in vitro and in animal models; following proteolytic cleavage, fMMAE is metabolized by cytochrome P450 (CYP) 3A4. EV excretion is not well characterized, fMMAE was primarily excreted via feces in a clinical study with another MMAE-containing ADC.

Age, sex, body weight, race, and ethnicity have no clinically meaningful impact on PK parameters. Renal impairment has no effect on the PK of ADC or free MMAE, with similar safety profile seen in patients with mild to severe renal impairment compared with patients with normal renal function. The effect of end-stage renal disease with or without dialysis remains unknown. Mild hepatic impairment can affect fMMAE exposure but did not impact the safety profile; data is limited regarding moderate-severe hepatic impairment [19,23].

MMAE is metabolized by CYP3A4 and is a substrate for P-glycoprotein (P-gp) efflux pump. While no drug interaction trials have been conducted, physiologically based PK modeling predicts increased exposure with dual P-gp and strong CYP3A4 inhibitors (e.g., ketoconazole) and decreased exposure with dual P-gp and strong CYP3A4 inducers (e.g., rifampin). Analysis of the phase III EV-301 study and the pooled safety dataset revealed no difference in treatment related adverse events (TRAE) in patients receiving P-gp or CYP3A4 inhibitors. There was a numerically higher percentage of serious TRAEs and grade 3 or higher TRAEs, but the interpretation is limited by small sample size and confounding factors [23].

2.2. Efficacy

Clinical studies of EV monotherapy for la/mUC are summarized in Table 1.

Table 1.

Clinical trials of enfortumab vedotin monotherapy in metastatic urothelial carcinoma.

	Trial (phase)	Reference	Study population		N	ORR (95% CI)	CR	DCR (95% CI)	Median DOR (95% CI) mo	Median PFS (95% CI) mo	Median OS (95% CI) mo
Previously treated	EV-101 (I)	[21]	Nectin-4 positive tumors Post platinum		112*	43% (33.6–52.6)	5%	71% (62.1–79.6)	7.4 (5.6–9.6)	5.4 (5.1–6.3)	12.3 (9.3–15.3)
	EV-102 (I)	[24]	Japanese population Post platinum		17^	35.3%	5.9%	76.5%	-	8.1 (3.5-NR)	-
	EV-201 (II)	[25–27]	Cohort 1- Post platinum and CPI		125	44% (35.1–53.2)	12%	72%	7.6 (4.93–7.46)	5.8 (4.9–7.5)	12.4 (9.46–15.57)
			Cohort 2- cisplatin ineligible, post CPI		89	52% (41–62)	20%	82%	10.9 (5.7-NR)	5.8 (5.03–8.28)	14.7 (10.51–18.2)
	EV-203 (II)	[28]	Chinese population Post platinum and CPI		40	37.5% (22.7–54.2)	2.5%	72.5%	NR	4.67	NR
	EV-301 (III)	[29,30]	Post platinum and CPI	EV	301	41.32% (35.57–47.25)	6.9%	71.88% (66.3–76.99)	7.62 (5.68–11.17)	5.55 (5.32–6.28)	12.91 (11.01–14.92)
				chemo+	307	18.58% (14.32–23.49)	3.4%	53.38% (47.52–59.17)	8.21 (5.68–9.56)	3.71 (3.52–3.94)	8.94 (8.25–10.25)
						p < 0.001		p < 0.001		HR 0.63 (0.53–0.76) p < 0.00001	HR 0.7 (0.58–0.85) p = 0.00015
1st line	EV 103 (Ib/II)	[15]	Cohort K- Cisplatin ineligible Treatment naïve		73#	45.2% (33.5–57.3)	4.1%	79.5% (68.4–88.0)	13.2 (6.14–15.97)	8.0 (6.05–10.35)	21.7 (15.21-NR)

Chemo- chemotherapy; CI- confidence interval; CPI- checkpoint inhibitor; DCR- disease control rate; DOR- duration of response; HR- hazard ratio; PFS- progression free survival; Mo- months; NR- not reached; ORR- objective response rate; OS- overall survival.

*treated at 1.25 mg/kg dose level of total 155 patients with UC included in the dose escalation and dose expansion cohorts; ^n-9 in arm A (dose 1.0 mg/kg), n-8 in arm B (dose 1.25 mg/kg); ⁺chemotherapy- docetaxel or paclitaxel or vinflunine, per investigator discretion; ^#EV monotherapy arm, treated on day 1 and 8 every 21 days.

EV-101 [21] was a phase I trial in patients with Nectin-4 positive solid tumors, including 155 la/mUC patients. In the 112 la/mUC patients treated at 1.25 mg/kg (the recommended phase II dose), there was a promising objective response rate (ORR) of 43%, including 5% complete responses (CR). EV-102 [24] showed comparable results in a small cohort (n = 17) of Japanese patients and provided PK data suggesting lack of clinically significant difference between North American and Japanese populations.

EV-201 was phase II, single arm, two-cohort study. Cohort 1 [25,26] included 125 patients with la/mUC after prior platinum-based chemotherapy and CPI, 50% had ≥ 3 previous lines of therapy. The ORR was 44%, including 12% CR rate, consistent across subgroups. At median follow-up of 22.3 months, the 12-month and 18-month OS rates were 50.4% and 34.2% respectively. Cohort 2 [27] included 89 cisplatin ineligible patients after prior exposure to CPI, 52% were ≥75 years old, 67% had moderate renal impairment, and 12% had Eastern Cooperative Oncology Group performance status (ECOG PS) of 2. The ORR was 52% including 20% CR rate. The analog study in Chinese patients, EV-203 [28], included 40 patients previously treated with platinum-based chemotherapy and CPI and reported ORR of 37.5% with 2.5% CR rates.

The global phase III study, EV-301 [29,30], was an open label trial randomizing 608 patients with la/mUC progressing after platinum-based chemotherapy and CPI to receive EV (n = 301) or chemotherapy per investigator choice: docetaxel, paclitaxel or vinflunine (n = 307). EV reduced the risk of death by 30% compared to chemotherapy (HR 0.7, 95% CI 0.58–0.85, p = 0.00015). PFS and ORR were both improved with EV compared to chemotherapy. Notably, 26.4% of patients achieving objective response (partial response [PR] or CR) remained alive and without disease progression at 24 months, compared with 19.1% in the chemotherapy arm.

In the front-line setting, cohort K of EV-103, a multicohort phase Ib/II study, enrolled cisplatin-ineligible patients with previously untreated la/mUC. Patients were randomly assigned to receive EV alone (n = 73) or EV/P (discussed below). Both arms were treated with EV on a 21-day cycle. EV monotherapy had a confirmed ORR of 45.2% including 4.1% CR rate. These responses were durable with median duration of response (mDOR) of 13.2 months, and 12-months OS of 80.7% (95% CI 69.42–88.13) [15].

2.3. Biomarkers

EV-101 [21] enrolled patients with Nectin-4 positive tumors, determined by immunohistochemistry (IHC) and measured by H-score (scale 0–300). The widespread overexpression of Nectin-4 seen in mUC in this study led to the removal of this requirement (>95% of prescreened cases exhibiting robust Nectin-4 expression), and subsequent studies in the EV development program did not enroll patients based on Nectin-4 expression. Retrospective assessment of Nectin-4 expression in EV-103 cohort A [14] and EV-201 [25] revealed similar near universal expression: median H-score in EV-201 cohort was 290 (range: 14–300). Responses were observed across Nectin-4 expression levels including cases with low/negative H-score. Therefore, despite an exploratory analysis conducted by the United States Food and Drug Administration (FDA) suggesting a trend toward higher H-score in the responders, EV was approved regardless of Nectin-4 expression [31].

Subsequent efforts to evaluate Nectin-4 expression level using different commercially available IHC assays suggests that there is more heterogeneity then was initially described, including a higher proportion of Nectin-4 negative urothelial tumors (17%-19.7% [32–34]) and different expression levels in tumors with variant histology [35] or across molecular subtypes [36]. Notably, markedly decreased Nectin-4 expression in metastases compared with matched primary tumor was demonstrated in one dataset, correlating with worse clinical outcomes on EV [34]. The reason for these differences compared with EV-101 and EV-201 data remains unclear. Likely explanations include use of different antibody clones and failure to adequately distinguish between membranous and cytoplasmic Nectin-4 expression.

NECTIN-4 gene amplification has recently emerged as a promising biomarker [37]. In two cohorts of mUC patients, EV treated (n = 108) and EV untreated (n = 103), NECTIN-4 amplifications evaluated via FISH were detected in 26% of cases and were associated with significantly enhanced expression of membranous Nectin-4 compared with non-amplified cases (median H-score 295 versus 90, p < 0.001). In the EV treated cohort, NECTIN-4 amplification was associated with a 96% ORR compared with 32% in the nonamplified tumors, with significantly improved PFS (HR 0.14, 95% CI 0.06–0.3, p < 0.001) and OS (HR 0.08, 95% CI 0.02–0.34, p < 0.001) adjusted for age, sex and Bellmunt risk score. Improved outcomes were also demonstrated comparing NECTIN-4 amplified tumors with nonamplified tumors highly expressing membranous nectin-4 (H-score ≥200). No effect of NECTIN-4 amplification on OS was seen in the EV untreated cohort, refuting potential prognostic bias of NECTIN-4 amplification.

Further validation is required to better define the clinical utilization of these biomarkers and rigorous efforts to identify new biomarkers are ongoing.

2.4. Safety and tolerability

2.4.1. General safety

In EV-301, grade ≥ 3 TRAEs occurred in 52.4% of patients in the EV arm (compared with 50.5% in the chemotherapy arm) [29,30], most commonly maculopapular rash (7.4%), fatigue (6.8%), decreased neutrophil count (6.1%, febrile neutropenia rate was 0.7%) and peripheral neuropathy (5.1%). Treatment-related deaths occurred in 7 patients (2.4%) due to abnormal hepatic function, hyperglycemia, pelvic abscess, pneumonia, septic shock, and multi-organ dysfunction syndrome (in 2 patients). A safety analysis of 310 patients included in the phase I/II studies reported grade 3–4 TRAEs occurring in 73% of patients, with 5 treatment-related deaths (1.6%) due to multi-organ dysfunction syndrome, respiratory failure, diabetic ketoacidosis, metabolic acidosis, and urinary tract obstruction [31]. TRAEs of special interest are detailed below.

Key safety data and TRAEs of special interest are summarized in Table 2.

Table 2.

Treatment-related adverse events summary- enfortumab vedotin, and pembrolizumab as monotherapy and combination.

	EV + Pembrolizumab trials						EV monotherapy trials				Pembrolizumab monotherapy trials
	[14–17]						[15,29,30]				[11,43–45]
	EV-103 DE/Cohort A		EV-103 Cohort K EV/P arm		EV-302 EV/P arm		EV-103 Cohort K EV arm		EV-301 EV arm		Keynote-361 Pembro arm		Keynote-052 Pembro arm
	N-45 (%)		N-76 (%)		N- 440 (%)		N-73 (%)		N-296 (%)		N-302 (%)		N-370 (%)
	Any Grade	Grade ≥3	Any Grade	Grade ≥3	Any Grade	Grade ≥3	Any Grade	Grade ≥3	Any Grade	Grade ≥3	Any Grade	Grade ≥3	Any Grade	Grade ≥3
Any-treatment related adverse event	–	–	–	48 (63.2)	428 (97.3)	252 (57.3)	-	35 (47.9)	278 (93.9)	152 (51.4)	192 (64)	57 (19)	249 (67.3)	78 (21.1)
Events leading to treatment discontinuation	11 (24.4)		36 (47.4)		154 (35.0)		14 (19.2)		45 (15.2)		48 (16)		34 (9.2)
Events leading to death	1 (2.2)		3 (3.9)		4 (<1.0)		2 (2.7)		7 (2.4)		2 (1)		1 (0.3)
Severe skin reactions	11 (24.4)	10 (22.2)	21 (27.6)	15 (19.7)	75 (17)	52 (11.8)	13 (17.8)	3 (4.1)	60 (20.3)	15 (5.0)	5 (2)	2 (1)	11 (3)	8 (2.2)
Pruritus	15 (33.3)	1 (2.2)	30 (39.5)	3 (3.9)	179 (40.7)	6 (1.4)	19 (26.0)	1 (1.4)	95 (32.1)	4 (1.4)	66 (22)	0	68 (18.4)	3 (0.8)
Maculopapular rash	16 (35.6)	5 (11.1)	35 (46.1)	13 (17.1)	144 (32.7)	34 (7.7)	21 (28.8)	1 (1.4)	48 (16.2)	22 (7.4)	40 (13)	0	45 (12.2)	2 (0.5)
Peripheral sensory neuropathy	25 (55.6)	2 (4.4)	39 (51.3)	1 (1.3)	228 (51.8)	18 (4.1)	32 (43.8)	2 (2.7)	100 (33.8)	9 (3.0)	–	0	0	0
Hyperglycemia	5 (11.1)	4 (8.9)	10 (13.2)	5 (6.6)	57 (13.0)	27 (6.1)	8 (11.0)	7 (9.6)	19 (6.4)	12 (4.0)	–	6 (2)	4 (1.1)	1 (<1)
Pneumonitis	4 (8.9)	1 (2.2)	7 (9.2)	4 (5.3)	42 (9.5)	16 (3.6)	3 (4.1)	0	–	–	13 (4)	4 (1)	17 (4.6)	5 (1.4)
Ocular disorder	–	–	20 (26.3)	0	94 (21.4)	0	21 (28.8)	0	55 (18.6)	2 (0.7)	–	0	–	–
Colitis	3 (6.7)	1 (2.2)	3 (3.9)	1 (1.3)	12 (2.7)	7 (1.6)	–	–	–	–	5 (2%)	4 (1%)	11 (3)	7 (1.9)
Hepatitis	–	–	2 (2.6)	2 (2.6)	14 (3.2)	8 (1.8)	–	–	–	–	2 (1)	1 (<1)	8 (2.2)	8 (2.2)
Diarrhea	21 (46.7)	2 (4.4)	22 (28.9)	5 (6.6)	123 (28.0)	17 (3.9)	20 (27.4)	4 (5.5)	72 (24.3)	10 (3.4)	56 (19)	9 (3)	34 (9.2)	4 (1.1)
Fatigue	23 (51.1)	5 (11.1)	43 (56.6)	7 (9.2)	131 (29.8)	14 (3.2)	29 (39.7)	6 (8.2)	92 (31.1)	19 (6.4)	73 (24)	7 (2)	67 (18.1)	9 (2.4)

DE- dose escalation; EV- enfortumab vedotin; EV/P- enfortumab vedotin and pembrolizumab; Pembro- pembrolizumab.

2.4.2. Drug exposure and modifications

EV is prescribed until disease progression or unacceptable toxicity. Median duration of treatment in EV-301 was 5 months (range: 0.5–19.4 months) [29], and in the pooled safety cohort (n = 720) 37% and 14% of patients received EV for ≥6 months and ≥12 months, respectively [19]. In EV-301, TRAEs leading to treatment interruptions, dose reductions, or treatment discontinuations occurred in 51.0%, 32.4%, and 13.5% of patients, respectively, most commonly due to peripheral sensory neuropathy. TRAEs are generally dose-dependent, and analysis of exposure impact on outcomes showed that dose modifications were associated with maintained benefit and lower risk of toxicity [22].

2.4.3. Adverse events of special interest

Cutaneous adverse events are frequent, reported in 58% (all grades) of the pooled safety cohort, and tend to occur early, most commonly in the first cycle (median time to first onset of severe skin reaction was 0.6 months, range: 0.1–8). The presumed mechanism of the dermatologic toxicities is ADC binding to Nectin-4 expressing normal cells in the epidermis, sweat glands epithelium and hair follicles. The clinical presentation varies in severity, distribution and morphology. The intertriginous, flexural, acral and possibly the truncal areas tend to be involved, often with erythematous, scaly, pruritic papules, and the most common symptoms are pruritus (34%) and maculopapular rash (23%). In the pooled safety cohort, grade 3–4 skin reactions were reported in 14% of patients, leading to EV discontinuation in 3.1% of patients. Dose interruptions can be effective, likely due to the short half-life, as are dose reductions. However, a quarter of patients resuming EV experienced recurrent severe skin reaction regardless of dose reduction. In the post-marketing setting, cases of severe cutaneous toxicity including fatalities such as Stevens-Johnson syndrome and toxic epidermal necrolysis were reported, resulting in a black box warning [19,38].

Peripheral neuropathy was reported in 53% (all grades) of the pooled safety cohort. Most patients presented with sensory neuropathy, but muscular weakness and motor neuropathy were also reported. Peripheral neuropathy is mediated through MMAE microtubule disruption. The median time to onset of grade ≥ 2 neuropathy is 4.9 months (range: 0.1–20). Neuropathy is the most common TRAE leading to treatment discontinuation (6% of the pooled safety cohort). Notably, of 296 patients with available follow-up, only 11% experienced complete resolution. Half of the remaining patients had residual grade ≥ 2 neuropathy at their last evaluation [19]. An exploratory FDA analysis did not identify a threshold cumulative exposure for increased risk of peripheral neuropathy [39].

Hyperglycemia at any grade was reported in 17% of patients on the pooled analysis cohort; 6.5% grade 3, 0.6% grade 4 and one patient (0.3%) with a fatal event. When hyperglycemia occurred, the median time to onset was 0.5 months (range: 0–20), patients with or without preexisting diabetes mellitus can be effected, though higher frequency was seen in patients with higher body mass index and in patients with higher baseline hemoglobin A1C. Patients with uncontrolled diabetes mellitus (hemoglobin A1C ≥ 8%) were excluded from EV clinical trials [19].

Pneumonitis/Interstitial lung disease is a rare potentially life-threatening toxicity reported in 3% of the pooled safety cohort, 0.8% were grade 3–4. Median time to onset was 2.9 months (range: 0.6–6) [19].

Ocular adverse events were reported in 40% of 384 patients in the phase I/II clinical trial undergoing routine ophthalmic exams (not performed in EV-301). Most symptoms were mild, common presenting symptoms were dry eyes and blurred vision. Median time to onset was 1.7 months (range: 0–30.6) [19].

3. Pembrolizumab for urothelial cancer

3.1. Mechanism of action and pharmacology

Pembrolizumab is a highly selective humanized IgG4 monoclonal antibody directed against the PD-1 receptor on T cells. By binding to the PD-1 receptor, pembrolizumab blocks its interaction with the ligands, thus releasing the PD-1-mediated inhibition on immune response. Pembrolizumab is administered intravenously at a fixed dose of 200 mg every 21 days, based on accumulated data across different cancer types demonstrating flat dose-exposure efficacy and full PD-1 saturation in both blood and tumor. The terminal half-life is 22 days. Age, gender, race, renal impairment, mild-moderate hepatic impairment, or tumor burden has not shown a clinically meaningful effect on drug clearance [40].

3.2. Clinical efficacy

Clinical studies of pembrolizumab for la/mUC are summarized in Table 3.

Table 3.

Clinical trials of pembrolizumab monotherapy in metastatic urothelial carcinoma.

	Trial (phase)	Reference	Study population		N	ORR (95% CI)	CR (95% CI)	DCR (95% CI)	Median DOR (95% CI) mo	Median PFS (95% CI) mo	Median OS (95% CI) mo
Previously treated	KEYNOTE-045 (III)	[41–43]	Post platinum	Pembro	270	21.9% (17.1–27.3)	10.0%	39.3%	29.7 (1.6 ± 60.5+)	2.1 (2.0–2.2)	10.1 (8.0–12.3)
				Chemo^	272	11% (7.6–15.4)	2.9%	44.8%	4.4 (1.4 ± 63.1+)	3.3 (2.4–3.5)	7.2 (6.1–8.0)
										HR 0.95 (0.79–1.14) p > 0.3	HR 0.71 (0.59–0.86) p < 0.001
1stline	KEYNOTE-052 (II)	[43–45]	Cisplatin ineligible		370	28.9% (24.3–33.8)	9.5%	47% (42–52)	33.4 (1.4 ± 60.7+)	2.5 (2.1–3.4)	11.3 (9.7–13.1)
	KEYNOTE-361 (III)	[11]	Cisplatin eligible and ineligible	Pembro + chemo#	351	54.7% (49.3–60.0)	15%	80.7%	8.5 (8.2–11.4)	8.3 (7.5–8.5)	17.0 (14.5–19.5)
				Chemo#	352	44.9% (39.6–50.2)	12%	75.9%	6.2 (5.8–6.5)	7.1 (6.4–7.9)	14.3 (12.3–16.7)
										HR 0.78 (0.65–0.93) p = 0.0033	HR 0.86 (0.72–1.02) p = 0.0407
				Pembro	307	30.3% (25.2–35.8)	11%	47.3%	28.2 (13.5-NR)	NA	15.6 (12.1–17.9)
				Exploratory analysis compared with chemo arm						HR 1.32 (1.09–1.58)	HR 1.01 (0.77–1.32)

Chemo- chemotherapy; CI- confidence interval; CR- complete response; DCR- disease control rate; DOR- duration of response; HR- hazard ratio; PD-L1- programmed death ligand 1; PFS- progression free survival; Mo- months; NR- not reached; ORR- objective response rate; OS- overall survival.

^chemotherapy per investigator choice: paclitaxel (175 mg/m2 Q3w), docetaxel (75 mg/m2 Q3w) or vinflunine (320 mg/m2 Q3w). ^#Gemcitabine plus cisplatin or carboplatin per investigator’s choice.

The phase III KEYNOTE-045 [41–43] trial randomized patients progressing after platinum-based chemotherapy to pembrolizumab (n = 270) or physician’s choice chemotherapy: paclitaxel, docetaxel or vinflunine (n = 272). mOS was 10.1 months with pembrolizumab versus 7.2 months for chemotherapy HR 0.71 (95% CI 0.59–0.86, p < 0.001), while mPFS was numerically but not significant higher. ORR and CR were higher in the pembrolizumab arm (21.9% and 10%) compared with the chemotherapy arm (11% and 2.9%), with longer mDOR of 29.7 versus 4.4 months.

The single arm phase II KEYNOTE-052 study evaluated pembrolizumab as first-line treatment in 370 cisplatin-ineligible patients [43–45]. 59% of patients had renal dysfunction, 28.9% of patients were ≥80 years old, 41.9% had ECOG PS 2 and 85.1% had visceral disease. ORR was 28.9% with 9.5% of patients achieving CR, mPFS was 2.5 months and mOS was 10.3 months. Ongoing responses seen in 44.8% and 39.4% of responders at 36 and 48 months, respectively.

KEYNOTE-361 [11] was a large global phase III trial randomizing previously untreated patients either cisplatin eligible (44%) or ineligible (56%) in a 1:1:1 ratio to receive pembrolizumab plus platinum-based chemotherapy (n = 351), platinum-based chemotherapy alone (n = 352) or pembrolizumab monotherapy (n = 307). The dual co-primary endpoints, PFS and OS for pembrolizumab plus chemotherapy versus chemotherapy alone, were not met. Based on the trial’s hierarchical statistical design no formal testing was done to compare the pembrolizumab and the chemotherapy-containing arms. Exploratory analysis in the ITT population and the subset of patients treated with carboplatin [46] did not suggest a difference in OS or PFS between pembrolizumab monotherapy and chemotherapy arm, though there were fewer grade 3–5 adverse events (AEs) and mDOR appeared longer with pembrolizumab.

3.3. Biomarkers

The most widely studied biomarker for pembrolizumab efficacy is programmed death ligand 1 (PD-L1) expression, determined using the PD-L1 IHC 22C3 pharmDx assay to calculate combined positivity score (CPS). CPS integrates PD-L1 staining on tumor and immune cells, commonly used with cutoff of CPS ≥ 10 or CPS < 10 [44].

In KEYNOTE-045, OS and PFS were analyzed separately for patients with CPS ≥ 10. The benefit for pembrolizumab appeared independent of PD-L1 expression [41,47]. A discovery biomarker analysis based on PD-L1 expression of KEYNOTE-052 suggested that patients with CPS ≥ 10 (n = 110) have better outcomes compared with patients with CPS < 10 (n = 251), including ORR (47.3% versus 20.7%), CR rates (20.9% versus 4.0%), mPFS (4.9 versus 2.1 months) and mOS (18.5 versus 9.7 months) [43,47]. Exploratory analysis of outcomes based on PD-L1 status in KEYNOTE-361 [11] suggested no difference in mOS for patients with CPS ≥ 10 (16.1 months for pembrolizumab versus 15.2 months with chemotherapy alone; HR 1.01, 95% CI 0.77–1.32). In a post-hoc analysis of carboplatin-treated patients, no OS benefit was detected with pembrolizumab regardless of CPS.

Overall, PD-L1 expression has not shown consistent predictive value in urothelial carcinoma to date. From a regulatory standpoint, FDA approval for first-line pembrolizumab monotherapy is now restricted to patients ineligible for any platinum-based chemotherapy.

Pembrolizumab received tumor agnostic approval for any solid tumor with high tumor mutation burden (TMB) defined as ≥ 10 mut/Mb. In an analysis of KEYNOTE-052 and KEYNOTE-045, TMB as a continuous variable was associated with improved outcomes. Using TMB high/low cutoff identified a positive PFS trend in KEYNOTE-045, while OS was improved regardless of TMB, and no trend for improved OS was seen in KEYNOTE-052 [47]. Multiple studies investigated the role of TMB to predict efficacy in urothelial cancer using different CPIs, assays, and thresholds and while the net evidence suggests TMB has a potential value [48], further validation and standardization is required.

Pembrolizumab is approved for tumors with microsatellite instability- high (MSI-H) or mismatch repair deficient (dMMR) solid tumors that exhausted standard treatments based on basket studies that included a subset of patients with urothelial cancer (ORR 50%) [40,49]. MSI-H/dMMR occurs more frequently in upper tract tumors (8.36–8.95%) compared with bladder tumors (2.11–2.3%) [50], and while evidence suggests these tumors are sensitive to CPI, data regarding combination therapies is scarce.

3.4. Safety and tolerability

3.4.1. General safety

The safety profile of pembrolizumab has been well documented, and no new signals emerged in the urothelial trials. In the pembrolizumab arm of KEYNOTE-045 [41,43], TRAEs of any grade rates were 62% (most commonly pruritus, fatigue and nausea), with grade ≥ 3 events occurred in 16.9% versus 50.2% in the chemotherapy arm. Four deaths (1.5%) were attributed to treatment with pembrolizumab due to pneumonitis, urinary tract obstruction, malignant neoplasm progression, and unspecified cause.

In the front-line setting, any grade TRAEs in KEYNOTE-052 [43–45] occurred in 67.3% (most commonly pruritus, fatigue and rash), grade 3–4 TRAEs occurred in 21.1% of patients and there was one treatment related death (0.3%) due to myositis. In KEYNOTE-361 [11], pembrolizumab monotherapy was associated with 17% grade ≥ 3 TRAEs, considerably lower than the chemotherapy containing arms (72% chemotherapy alone and 75% in the combination arm). In the monotherapy arm, the most common grade ≥ 3 events were diarrhea, fatigue, and hyponatremia, and two deaths were attributed to treatment (cardiac failure and malignant neoplasm progression).

Key safety data and TRAEs of special interest are summarized in Table 2.

3.4.2. Drug exposure and modifications

Pembrolizumab is prescribed for up to 2 years. TRAEs leading to treatment discontinuation occurred in 7.1% of patients in KEYNOTE-045 [41,43], most common causes were pneumonitis (1.9%) and interstitial lung disease (0.8%). Rates of treatment discontinuation due to TRAEs were 9.5% in KEYNOTE-052 [43–45] and 16% with pembrolizumab monotherapy in KEYNOTE-361 [11]. There are no dose modifications with pembrolizumab.

3.4.3. Adverse events of special interest

Immune related adverse events (irAE) were reported in 19.5% of patients in KEYNOTE-045 [41,43], predominantly thyroid abnormalities, pneumonitis and colitis, and most were mild. Most frequently reported grade ≥ 3 irAE were pneumonitis (2.6%), colitis (1.9%), severe skin reactions (0.8%) and nephritis (0.8%). In KEYNOTE-052 [43–45] irAEs were reported in 26.5% of patients with 10.8% experiencing grade ≥ 3 events including severe skin reactions (2.2%), hepatitis (2.2%), colitis (1.9%), adrenal insufficiency (1.9%), pneumonitis (1.4%) and type 1 diabetes mellitus (1.1%). The most common all grade irAEs in the pembrolizumab monotherapy arm of KEYNOTE-361 [11] were hypothyroidism (10%), pneumonitis (4%), hyperthyroidism (3%), and severe skin reactions (2%). Grade ≥ 3 irAE were uncommon, with pneumonitis, severe skin reactions, colitis, and pancreatitis each reported in 1% of patients.

4. Enfortumab vedotin and pembrolizumab for urothelial cancer

4.1. Mechanism of action and pharmacology

Preclinical models have shown that EV induces immunogenic cell death via endoplasmic reticulum stress mediating release of damage-associated molecular patterns (extracellular secretion of ATP, passive release of high mobility group protein B1, and surface exposure of calreticulin) which in turn trigger activation of anticancer immunity [20,51,52]. As immunogenic cell death involves tumor antigen presentation and T-cell activation, combining PD-1 inhibition can potentially prevent evasion by PD-L1 expressing tumor cells and enhance antitumor activity. In Nectin-4 expressing mouse models, treatment with EV and PD-1 inhibitor indeed resulted in durable immunity [51]. The mechanism of action of EV/P is illustrated in Figure 1.

Figure 1.

Mechanism of action of enfortumab vedotin (EV) and pembrolizumab.

EV is an ADC composed of an anti Nectin-4 monoclonal antibody conjugated via a protease-cleavable linker to MMAE. EV binding to Nectin-4 triggers internalization of the ADC-antigen complex. Lysosomal proteolytic cleavage releases MMAE to the intracellular space, which then also diffuses to the extracellular space, leading to a bystander killing effect. MMAE causes microtubule disruption and endoplasmic reticulum stress, resulting in cell death. Damage-associated molecular patterns released during immunogenic cell death promotes APC maturation, which in turn activate naïve T cells. Pembrolizumab prevents PD-1/PD-L1 mediated T-cell deactivation by inhibiting PD-1, thus promoting anti-tumor immune response.

Created in BioRender. BioRender.com/e44p763.

ADC- antibody-drug conjugate; APC- antigen presenting cell; MHC-TCR- major histocompatibility complex-T cell receptor; MMAE- monomethyl auristatin E; PD-1- programmed death 1; PD-L1- programmed death ligand 1.

EV/P is administered intravenously, with pembrolizumab at a fixed dose of 200 mg on day 1 and EV at a dose of 1.25 mg/kg up to a maximal dose of 125 mg on days 1 and 8 of a 21-day cycle. The altered EV schedule compared with the monotherapy 28-day schedule was deemed acceptable based on the predicted similarity of PK exposures with similar relative dose intensity. In PK analysis from EV 103 cohort A (described below), combination with pembrolizumab did not impact EV PK [14].

4.2. Clinical efficacy

Clinical studies of EV/P for la/mUC are summarized in Table 4.

Table 4.

Efficacy summary of enfortumab vedotin and pembrolizumab in metastatic urothelial carcinoma.

	EV-103		EV-302
	[14,15,53,54]		[16,17,55–57]
	Cohort DE/A	Cohort K	ITT		Cisplatin eligible		Cisplatin ineligible
	EV/P N-45	EV/P N-76	EV/P N-442	Chemo N-444	EV/P N-244	Chemo N-234	EV/P N-198	Chemo N-210
Confirmed ORR (95% CI)	73.3% (58.1–85.4)	64.5% (52.7–75.1)	67.5% (62.9–71.9)	44.2% (39.5–49.0)	70.8% (64.6–76.4)	53% (46.4, 59.6)	63.9% (56.7–70.7)	34.9% (28.5–41.8)
CR	15.6%	10.5%	30.4%	14.5%	32.5%	15.5%	24.7%	9.1%
DCR	84.4%	86.9%	86.5%	78.0%	84.6%	83.6%	86.6%	72.2%
Median time to response (range) months	2.1	2.07 (1.1–6.6)	2.1 (1.3–12.3)	2.1 (1.6–8.3)	2.1	2.1	2.1	2.1
Median duration of response (95% CI) months	22.1 (8.38-NR)	Not reached (10.25-NR)	23.3 (17.8-NR)	7.0 (6.2–9.0)	Not reached (18.2-NR)	8.3 (5.9–10.9)	Not reached (16.3-NR)	6.6 (5.6–10.2)
12 months PFS	55.0% (38.84–68.58)	55.1% (41.84–66.48)	51.4%	21.7%	53.9%	25.8%	46.7%	16.8%
24 months PFS			37.1%	12.6%
Median PFS (95% CI) months	12.7 (6.11-NR)	Not reached (8.31-NR)	12.5 (10.4–16.6)	6.3 (6.2–6.5)	14.6 (10.4-NR)	6.5 (6.3–8.1)	10.6 (8.3–15.3)	6.1 (5.3–6.2)
HR (95% CI)			0.48 (0.41–0.57) p < 0.00001		0.48 (0.38–0.62)		0.43 (0.33–0.55)
12 months OS	83.4% (68.25–91.72)	80.7% (69.42–88.13)	77.7%	61.1%	81.4%	68.0%	74.1%	54.3%
18 months OS			69.5%	44.7%	70.4%	50.7%	68.4%	38.2%
24 months OS			60.1%	35.4%
Median OS (95% CI) months	26.1 (15.51-NR)	22.3 (19.09-NR)	33.8 (26.1–39.3)	15.9 (13.6–18.3)	36.7 (31.5-NR)	18.7 (16.6–22.1)	25.6 (22.7–36.1)	12.7 (11.0–14.7)
HR (95% CI)			0.51 (0.43–0.61) p < 0.00001		0.54 (0.42–0.70)		0.50 (0.39–0.64)

Chemo- chemotherapy; CI- confidence interval; CR- complete response; DCR- disease control rate; DE- dose escalation; DOR- duration of response; EV/P- Enfortumab vedotin and pembrolizumab; HR- hazard ratio; ITT- intention to treat; PFS- progression free survival; NR- not reached; ORR- objective response rate; OS- overall survival.

The dose escalation (DE) and dose expansion (Cohort A) of the EV 103 phase Ib/II study included 45 cisplatin-ineligible patients with previously untreated la/mUC [14]. 84.4% of patients had visceral disease, 31.1% with liver metastases. The confirmed ORR was 73.3%, with 7 patients (15.6%) achieving CR. Responses were rapid (87.9% of responses observed at first assessment) and durable with mDOR of 22.1 months (95% CI: 8.38-not reached [NR]). At median follow-up of 47 months, mPFS was 12.7 months and mOS was 26.1 months [53]. With extended follow-up (median 62.1 months), PFS rates remained stable at 38.2% and the 5 years OS was 41.5% [54].

Cohort K of EV-103 randomized 151 cisplatin-ineligible previously untreated patients to receive EV monotherapy (N = 73) or EV/P (N = 76) [15]. The study was not powered to directly compare the two arms but aimed to show the contribution of components of EV and pembrolizumab to the regimen. 84.2% of the EV/P cohort had visceral disease, 17.1% with liver metastases. The confirmed ORR with EV/P was 64.5%; 8 patients (10.5%) achieved CR and 97.1% of assessable patients had target lesion shrinkage. Median time to response was 2.1 months and primary disease progression rates were 7.9%. With a median follow-up of 14.8 months, the PFS and OS rates at 12 months were 55.1% and 80.7% respectively. Median DOR was not reached, with 65.4% of responders remaining progression free at 12 months.

A combined analysis of patients treated with EV/P in EV-103 included 121 patients from the DE cohort (n = 5), cohort A (n = 40), and cohort K (n = 76) [39]. The confirmed ORR was 67.8% (95% CI 58.7–76.0), with 12.4% CR rate. Responses were similar between exploratory subgroups (including age, sex, PD-L1 status, and primary tumor location) and were durable with mDOR of 22.1 months (95% CI 17.15-NR).

The pivotal phase III study EV-302 [16] was a global open label trial randomizing patients with previously untreated la/mUC to receive EV/P (n = 442) or platinum (cisplatin or carboplatin, based on eligibility) plus gemcitabine (n = 444). Pembrolizumab was given for up to 35 cycles with no maximum cycles of EV; chemotherapy was given for up to 6 cycles. Maintenance avelumab was permitted via a protocol amendment but not mandated or provided. The median age was 69 years, 76.7% were male and 27% had upper tract primary.

At median follow-up of 17.2 months, the risk of death was reduced by 53% with EV/P compared to chemotherapy (HR 0.47 95% CI 0.38–0.58, p < 0.001), with mOS of 31.5 versus 16.1 months. The risk of progression or death was similarly reduced by 55% with EV/P compared to chemotherapy (HR 0.45 95% CI 0.38–0.54, p < 0.001), with mPFS of 12.5 versus 6.3 months. The benefit was observed in all prespecified subgroups, including cisplatin eligibility, PD-L1 status and metastatic sites (liver metastasis, visceral metastasis, and lymph-node only disease). The confirmed ORR was significantly higher with EV/P compared to chemotherapy- 67.7% (95% CI 63.1–72.1) versus 44.4% (95% CI 39.7–49.2), p < 0.001. Notably, CR was achieved in 29.1% of patients in the EV/P arm compared with 12.5% in the chemotherapy arm. Durable responses were observed: mDOR was not reached for EV/P (95% CI 20.2-NR) compared with 7 months for chemotherapy (95% CI 6.2–10.2).

Updated analysis with 29.1 months of median follow-up was presented at the 2025 ASCO Genitourinary Cancers Symposium [17]. With extended follow-up, the benefit of EV/P over chemotherapy was maintained for PFS (mPFS 12.5 versus 6.3 months, HR 0.48; 95% CI 0.41–0.57, p < 0.00001) and OS (mOS 33.8 versus 15.9 months, HR 0.51; 95% CI 0.43–0.61, p < 0.00001), seen across subgroups. Median duration of response with EV/P was 23.3 months (95% CI 17.8-NR) versus 7.0 months with chemotherapy (95% CI 6.2–9.0). Among patients with confirmed CR (30.4% of patients in the EV/P arm and 14.5% in the chemotherapy arm), CR was maintained at 24 months in 74.3% with EV/P versus 43.2% with chemotherapy.

Subset analysis based on cisplatin eligibility showed that cisplatin-eligible patients were generally younger, had better ECOG PS and had lower rates of upper tract disease [55]. The outcomes for cisplatin-eligible patients in the control arm appeared better compared with the ITT control arm outcomes, as expected with cisplatin-based chemotherapy. Regardless, efficacy results were consistent with the ITT (detailed in Table 3) with clear benefit for EV/P compared to chemotherapy. For cisplatin-ineligible patients enrolled on EV-302 [56], 83.6% of patients were deemed ineligible based on renal function. While outcomes were generally less favorable in both arms compared with the ITT and the cisplatin-eligible cohort, reflecting a patients’ population with upfront worse prognosis, the benefit with EV/P versus chemotherapy was consistent.

In the chemotherapy arm, 70.5% of patients received subsequent treatment. Maintenance CPI was used in 32.2% of patients (30.4% received avelumab), more frequently in the cisplatin-eligible cohort (37.2% versus 26.7%). 26.4% of patients received CPI at disease progression. In the EV/P arm 29% of patients received subsequent treatment, most commonly platinum-based chemotherapy (24.9%).

4.3. Biomarkers

To date, no biomarker has been established for treatment with EV/P. In EV-103 cohort DE/A and EV-103 cohort K exploratory analysis found no association between responses and PD-L1 expression (CPS <10 or CPS ≥ 10) or Nectin-4 expression [14,15].

Patients enrolled to EV-302 were stratified by PD-L1 expression, with 58% CPS ≥ 10 and 42% CPS < 10 in both arms. Clear benefit was demonstrated regardless of PD-L1 expression (HR for PFS was 0.42 and 0.5 for CPS ≥ 10 and CPS < 10, respectively, and HR for OS was 0.49 and 0.44 for CPS ≥ 10 and CPS < 10, respectively). Nectin-4 IHC was tested in 394 of 442 patients in the EV/P arm, median H-score was 280 and only 3 patients (0.8%) had an H-score of 0. Consistent benefit with EV/P compared to chemotherapy was seen across Nectin-4 expression levels (HR for PFS was 0.5 and 0.41 for H-score <275 and ≥ 275, respectively). In an exploratory analysis of four subgroups based on combined Nectin-4 and PD-L1 expression (H-score <275/CPS <10, H-score <275/CPS ≥10, H-score ≥275/CPS <10 and H-score ≥275/CPS ≥10), the observed benefit remains irrespective of expression levels [57].

4.4. Safety and tolerability

4.4.1. General safety

In EV-302, the most common TRAEs with EV/P were peripheral sensory neuropathy (51.8%), pruritus (40.7%) and alopecia (33.2%); common TRAE with chemotherapy were anemia (56.6%), neutropenia (41.6%) and nausea (38.8%). Grade ≥ 3 TRAEs occurred in 57.3% of patients in the EV/P arm, most commonly maculopapular rash (7.7%), hyperglycemia (5.0%) and neutropenia (4.8%). The chemotherapy arm had higher rate of grade ≥ 3 TRAEs (69.5%), most commonly anemia, neutropenia, and thrombocytopenia. Treatment-related deaths occurred in 4 patients (<1.0%) in the EV/P arm (multiorgan failure, immune mediated lung disease, diarrhea, and asthenia) and in 4 patients (<1.0%) in the chemotherapy arm (sepsis, febrile neutropenia, neutropenic sepsis, and myocardial infarction). With extend follow-up, no new safety signals were seen [17]. In a combined analysis of patients treated with EV/P across EV-103 cohorts (n = 121) fatal adverse events occurred in 6 (5%) patients including sepsis, bullous dermatitis, myasthenia gravis, and pneumonitis/interstitial lung disease [39].

4.4.2. Drug exposure and modifications

In EV-302 the median duration of treatment in the EV/P arm was 9.4 months (range: 0.3–31.9), 7 months with EV (range: 0.3–31.9) and 8.5 months with pembrolizumab (range: 0.3–28.5) [16]. Notably, at median follow-up of 17.2 months, 32.6% of patients in the EV/P arm remain on treatment. Per protocol, none of the patients on the chemotherapy arm remained on treatment (planned completion of therapy after 6 cycles). In a combined analysis of patients in EV-103 and EV-302 (n = 564), 59% and 24% of patients were exposed to treatment for ≥6 months and ≥12 months, respectively [19].

TRAE leading to dose reductions occurred in 40.7% of patients in the EV/P arm of EV-302. Discontinuation of individual drugs was permitted; 35% discontinued any study drug, 29.5% of patients discontinued EV and 21.4% of patients discontinued pembrolizumab [16]. The most common TRAEs resulting in discontinuation were peripheral neuropathy (10.7%) for EV, and pneumonitis (4.8%) or rash (3.4%) for pembrolizumab. A combined analysis of 121 patients treated in EV-103 reported 45% dose reductions and 69% dose interruptions. Treatment with EV was discontinued in 36% of patients and both study drugs were discontinued in 28% of patients. Peripheral neuropathy was the most common TRAE resulting in treatment modifications [19,39].

4.4.3. Adverse events of special interest

Treatment with EV/P is associated with distinct safety profile associated with each drug and overlapping toxicities. Key clinically relevant recommendations are detailed below, a comprehensive discussion of the management of EV/P-related toxicities is beyond the scope of this review, and algorithms for monitoring and treatment have been proposed previously [38,58]. Table 2 summarizes the key safety data of EV and pembrolizumab in combination and as monotherapies.

Cutaneous adverse events at any grade occurred in 70% of 564 patients treated with EV/P (EV-103 and EV-302), including 17% grade 3–4 skin reactions and 1 patient (0.2%) with fatal bullous dermatitis. Median time to onset of severe skin reactions was 1.7 months (range: 0.1–17.2). The risk of cutaneous toxicity reported with EV/P is higher compared with the risk seen with EV and pembrolizumab as monotherapies, with higher rates of grade ≥ 3 events. Differentiation between EV-associated and pembrolizumab-associated skin reactions is challenging considering the wide variability of clinical presentations. Initial management is similar regardless of attribution and consists of close monitoring, especially during the initial cycles, and early use of antihistamines and topical steroids. If treatment interruption is required and attribution is not clear, both agents should be held. Oral corticosteroids should be considered in selected grade ≥ 3 reactions and specialized dermatology consultation is strongly recommended in severe and persistent cases [19,38,58].

Peripheral neuropathy rates in the pooled safety cohort (EV-103 and EV-302) were 76% at any grade, 36% at grade 2 and 7% at grade 3. Median time to onset of grade ≥ 2 neuropathy was 6 months (range: 0.3–25). Of 373 patients with available follow-up, 13% had complete resolution of symptoms; 45% of the remaining patients still had grade ≥ 2 residual neuropathy at last evaluation. Longer follow-up may be required to adequately measure recovery rates. In the extended follow-up data of EV-103 DE/A (median follow-up 47 months), the median time to neuropathy improvement by at least 1 grade was 6.6 months (range: 0.3–27.4) and median time to resolution was 7.2 months (range: 3.5–19.1). Numerically, peripheral neuropathy was more frequent and presented later for patients treated with EV/P than was seen with EV monotherapy, though no formal comparisons can be made. Nonetheless, peripheral neuropathy is presumed to be mediated primarily by EV, especially given the rarity of immune-related neuropathies. Possible alternative explanation for the higher neuropathy rates with EV/P is the higher efficacy resulting in longer exposure to EV (median duration of treatment with EV of 7 versus 5 months with monotherapy), and the longer time to neuropathy onset may reflect higher frequency of dose modifications or the slightly lower dose intensity with 21-day compared with 28-day cycle [19,53,58]. Patients should be monitored closely for symptoms of new or worsening peripheral neuropathy. EV dose interruptions and dose reductions are advised for grade 2 events, in patients developing grade ≥ 3 peripheral neuropathy permanent EV discontinuation is required [19].

Hyperglycemia at any grade was reported in 13% of patients treated with EV/P in EV-302, with grade ≥ 3 in 6.1% of cases and 1 patient (0.2%) developing type 1 diabetes mellitus. Blood glucose requires monitoring during treatment with EV/P, especially in patients with high body mass index or high baseline hemoglobin A1C, and EV should be held if blood glucose is ≥250 mg/dL. While most cases of hyperglycemia in patients treated with EV/P are EV-associated, awareness is warranted for immune-mediated type 1 diabetes mellitus, a rare irreversible irAE associated with pembrolizumab (reported incidence rates 0.2–2.2% [40,59]).

Pneumonitis/interstitial lung disease occurred in 10% of the pooled safety cohort (EV-103 and EV-302), with grade 3–4 in 4% of cases and two (0.4%) fatal events. The median time to onset of pneumonitis/interstitial lung disease was 4 months (range: 0.3–26). The incidence appears higher than the reported incidence of each drug individually. Attribution is challenging and both EV and pembrolizumab should be held in patients developing symptomatic pneumonitis/interstitial lung disease [19,40,58].

Ocular adverse events were reported in 21.8% of patients treated with EV/P in EV-302, all were grade 1–2 and most (82 of 94 patients) had dry eyes. Similarly, in a combined analysis of EV/P treated patient on EV-103 grade 1–2 dry eyes occurred in 25% of cases.

Immune related adverse events were consistent with prior data with no new safety signal (excluding skin/pulmonary events noted above). Additional observed grade ≥ 3 irAEs included hepatitis (1.8%), colitis (1.6%) and pancreatitis (0.9%). Notably, while incidence of colitis in EV-302 was on par with prior experience of pembrolizumab monotherapy, the rates of diarrhea were higher, and were consistent with reports of EV monotherapy. Close monitoring and prompt evaluation in cases concerning for immune-related colitis/enteritis is recommended.

4.5. Patient-reported outcomes

Patient-reported outcomes were reported for 65 of the 76 patients treated with EV/P in EV-103 cohort K [60]. Clinically meaningful reduction in pain at week 12 compared to baseline (persisting through week 24), improvement in worst pain at week 21, and improved scores for worst, average, interference, and severity in weeks 4–24 were demonstrated with EV/P. Quality of life was maintained with stable functioning and symptoms scores and improvement in emotional and sleep disturbance compared to baseline.

Recently, patient-reported outcomes from EV-302 were presented at ASCO annual meeting 2024 [61]. Time to pain progression was numerically longer with EV/P (14.2 versus 10.0 months with chemotherapy), but no statistically significant difference between the treatment arms was detected (HR 0.92, 95% CI 0.72–1.2, p-0.48). Change in worst pain for the whole cohort did not meet the pre-defined clinically meaningful threshold, but for approximately one-third of patients reporting moderate to severe pain at baseline, both treatment arms resulted in meaningful improvement, with greater benefit seen with EV/P (p-0.04). Clinically meaningful changes in global health and quality of life measured using the EORTC QLQ-C30 GHS/QoL questionnaire were seen only for EV/P-treated patients with baseline moderate to severe pain and not with chemotherapy (p-0.008). When analyzed separately versus cisplatin or carboplatin, no significant differences were detected, though patients on the EV/P arm for both cohorts reported a transient worsening global health and quality of life through week 3. As expected, cisplatin appears to result in a worse quality of life than carboplatin. Over the first 26 weeks, EV/P resulted in significantly improved functioning across domains including physical, cognitive and role functioning, with borderline significant improvement in emotional and social functioning.

Overall, the patient-reported outcomes complement the clinical outcomes seen with EV/P and do not suggest a treatment-associated negative impact on quality of life.

5. Regulatory affairs

On 3 April 2023, the Food and Drug Administration (FDA) granted accelerated approval for EV/P for patients with la/mUC ineligible for cisplatin based on results from EV-103 cohort DE/A and cohort K [62]. On 15 December 2023, following the results of the phase III trial, EV-302, the FDA approved EV/P for all patients with la/mUC regardless of cisplatin eligibility [63].

The European Medicine Agency (EMA) approved EV/P for first-line treatment of la/mUC on 28 August 2024 [64]. Combination treatment with EV/P was also approved by Japan’s Ministry of Health, Labour and Welfare on 24 September 2024 [65] and by China’s National Medical Products Administration approved the combination on 8 January 2025 [66].

6. Current status and future directions

EV/P is currently considered the preferred regimen for previously untreated patients with la/mUC regardless of cisplatin eligibility, as reflected in recent updates of international guidelines including the National Comprehensive Cancer Network (NCCN) [67], the European Society for Medical Oncology (ESMO) [68], and the European Association of Urology (EAU) [69]. In cases where EV is not available or contraindicated, treatment alternatives include cisplatin, gemcitabine, and nivolumab based on CHECKMATE-901 [13] (for cisplatin-eligible patients only) and platinum- based chemotherapy followed by maintenance avelumab based on JAVELIN Bladder 100 [9,10].

There is no established second-line preferred regimen in the post EV/P setting. Platinum-based chemotherapy was the most commonly administered regimen for patients receiving subsequent treatment in the EV/P arm of EV-302 (110 of 140 patients, 78.6%) [16], but data regarding efficacy has not been presented. Other alternatives include erdafitinib for selected patients with FGFR3 alterations [70], fam-trastuzumab deruxtecan for selected patients with HER2 overexpression [71], and single agent chemotherapy [72–76]. In the absence of data to guide clinical decisions, the choice of second-line treatment is guided by the toxicity profile as well as patient and physician preferences.

Clinical trials attempting to further improve outcomes by combining EV/P with sacituzumab govitecan, a TROP-2 targeting ADC with topoisomerase payload (NCT04724018), or by combining EV with biphasic antibodies targeting PD-1 with either lymphocyte activation gene 3 (LAG-3) or T cell immunoglobulin and ITIM domain (TIGIT, NCT05845814) are ongoing. Other efforts focus on defining the efficacy of EV/P in pure variant and rare genitourinary malignancies (NCT05756569 and NCT06041503).

In early disease setting, two highly anticipated phase III trials evaluating EV/P as a perioperative treatment for muscle invasive disease have completed accrual and await data maturation: EV-304/KEYNOTE-B15 (NCT04700124) in cisplatin eligible patients compared with cisplatin and gemcitabine and KEYNOTE-905/EV-303 (NCT03924895) in cisplatin ineligible patients compared with pembrolizumab alone or upfront surgery. Several phase II trials are currently underway evaluating the role of EV/P for node positive disease (NCT05239624), as induction treatment followed by definitive radiotherapy for patients unfit or refusing cystectomy (NCT05879653) and for upper tract urothelial carcinoma (NCT06356155 and NCT05775471). Ongoing clinical trial combining EV/P are summarized in Table 5, additional studies of EV in combination with different CPIs are also underway.

Table 5.

Ongoing trials with combination enfortumab vedotin and pembrolizumab for urothelial carcinoma.

Trial (phase)	Population	Intervention		Status
Metastatic urothelial carcinoma
NCT05845814 (I/II) KEYMAKER-U04	Metastatic urothelial carcinoma Treatment naive	Randomized, open label, multicohort	A: EV/biphasic Ab [P + favezelimab (anti LAG-3)] B: EV/biphasic Ab [P + vibostolimab (anti TIGIT)] C: EV/P	Active, Not recruiting
NCT04724018 (I) DAD-IO	Metastatic urothelial carcinoma Treatment naive	Nonrandomized cohorts	EV/P + Sacituzumab govitecan	Active, Not recruiting
Variant and rare histology
NCT05756569 (II)	Locally advanced/metastatic bladder cancer of variant histology (excluding pure sarcomatous or neuroendocrine)	Single arm	EV/P	Active, recruiting
NCT06041503 (II) E-VIRTUE	Pretreated patients with rare genitourinary malignancies	Nonrandomized cohorts^	EV EV/P	Planned, Not yet recruiting
Muscle invasive bladder cancer
NCT04700124 (III) EV-304/KN-B15	Muscle-invasive urothelial carcinoma cT2-4aN01M0 or cT1-4aN0-1M0 Cisplatin eligible	Randomized, Open label	EV/P x4→RC→EV/P x5, P to complete 1 year. GC x4→RC#	Completed, results pending
NCT03924895 (III) EV-303/KN-905	Muscle-invasive urothelial carcinoma, cT2-4aN01M0 or cT1-4aN0-1M0 Cisplatin ineligible/declining	Randomized, Open label	A: P x3→RC→ P up to 1 year B: RC C: EV/P x3→RC→EV/P x6, P to complete 1 year.	Completed, results pending
NCT05239624 (II) EV-ECLIPSE	Locally advanced and/or node positive urothelial carcinoma	Single arm	EV/P x6→RC→ P to complete 1 year.	Active, recruiting
NCT05879653 (II) PEVRAD	Muscle invasive urothelial carcinoma cT2-4aN0M0 Unfit or refusing radical cystectomy	Single arm	EV/P x4→maximal TURBT→ definitive radiotherapy to the bladder.	Active, recruiting
Upper tract urothelial carcinoma
NCT06356155 (II) NEPTUNE	High-grade localized/locally advanced upper tract urothelial carcinoma. Cisplatin eligible	Single arm	EV/P x4-> Definitive surgery→ P to complete 1 year.	Planned, Not yet recruiting
NCT05775471 (II)	High risk upper tract urothelial carcinoma	Single arm	EV/P*→ Definitive surgery→ adjuvant P	Active, recruiting

Ab- antibody; EV- enfortumab vedotin; LAG-3- lymphocyte-activation gene 3; p- pembrolizumab; RC- radical cystectomy; TIGIT- T cell immunoglobulin and ITIM domain; TURBT- transurethral resection of bladder tumor.

^ allocation based on prior exposure to checkpoint inhibitor; ^#Amended to allow adjuvant nivolumab; *number of cycles not stated.

As the therapeutic landscape of la/mUC evolves, many challenges remain. These include optimizing patient selection via development and validation of biomarkers, tailoring escalation/de-escalation strategies, mitigating treatment-related toxicities, and establishing optimal treatment sequencing for patients after progression on EV/P. With several novel Nectin-4 targeting agents under development and emerging biomarker-guided alternatives including combination of disitamab vedotin, a HER-2 targeting ADC with MMAE payload, and pembrolizumab showing promising preliminary results in treatment-naïve patients [77], understanding the primary and acquired resistance mechanisms is key to guide future drug development and improve patients’ outcomes.

7. Conclusions

Combination treatment with enfortumab vedotin and pembrolizumab revolutionized the management of locally advanced and metastatic urothelial carcinoma, establishing a new standard of care and offering hope for prolonged survival and improved quality of life.

Funding Statement

This work was supported in part by National Cancer Institute Cancer Center Support grant [P30 CA008748].

Article highlights

Background

• Locally advanced or metastatic urothelial cancer (la/mUC) is an aggressive malignancy, associated with poor outcomes. Enfortumab vedotin (EV) and Pembrolizumab are both established advanced-line treatments for patients with la/mUC.

• Combination treatment with EV and pembrolizumab (EV/P) was recently approved for previously untreated patients with la/mUC.

Mechanism of action and pharmacology

• EV is an antibody-drug conjugate targeting Nectin-4 with monomethyl auristatin E (MMAE) payload. Pembrolizumab is an immune checkpoint inhibitor targeting programmed death 1 (PD-1).

• The combination is administered in a 21-day cycle, recommended dosing for EV is 1.25 mg/kg on days 1 and 8 and for pembrolizumab is 200 mg on day 1. Treatment is continued until progression or unacceptable toxicity, for up to 35 cycles of pembrolizumab with no maximum cycles of EV.

Clinical efficacy

• The phase Ib/II EV-103 cohort A and cohort K evaluated combination EV/P in previously untreated cisplatin-ineligible patients with la/mUC. Objective response rates (ORR) were 73.3% and 64.5%, and durable responses were seen.

• EV-302 was a phase III trial randomizing previously untreated patients with la/mUC to receive EV/P or standard of care platinum-based chemotherapy. Compared with chemotherapy, EV/P significantly improved progression free survival [median 12.5 versus 6.3 months, HR 0.48 (95% CI 0.41–0.57), p < 0.00001] and overall survival [medial 33.8 versus 15.9 months, HR 0.51 (95% CI 0.43–0.61), p < 0.00001)]. ORR was 67.5% with EV/P versus 44.2% with chemotherapy, and 30.4% of patients treated with EV/P achieved complete response versus 14.5% with chemotherapy. The observed benefit has been persistent across subgroups including cisplatin eligibility, PD-L1 or Nectin-4 expression and metastatic sites.

• Biomarkers No validated biomarkers have been established for treatment with EV/P.

Safety

• Treatment related adverse events (TRAEs) grade ≥ 3 occurred in 57.3% of patients treated with EV/P in EV-302 (versus 69.5% in the chemotherapy arm), most commonly maculopapular rash, hyperglycemia and neutropenia. TRAEs of special interest include cutaneous toxicities, peripheral neuropathy, hyperglycemia and pneumonitis.

• TRAEs resulting is dose reductions or treatment discontinuation occurred in 40.7% and 35% of patients treated with EV/P in EV-302, most commonly due to peripheral neuropathy.

Patient-reported outcomes

• Treatment with EV/P was not associated with detrimental effect on quality of life.

Regulatory affairs and guidelines

• On December 15, 2023, the FDA approved EV/P for all patients with la/mUC, expanding the previous accelerated approval limited to cisplatin ineligible patients. The European Medicine Agency (EMA) approved EV/P for first-line treatment of la/mUC on August 28, 2024.

• International guidelines recommend EV/P as the preferred regimen for previously untreated patients with la/m UC.

Future directions

• Ongoing studies of EV/P include perioperative treatment for localized urothelial carcinoma, combination with other agents and urothelial carcinoma with variant histology.

Conclusion

• EV/P revolutionized the management of la/mUC, establishing a new standard of care and offering hope for prolonged survival and improved quality of life.

Author contributions

Michal Sternschuss- conceptualization, writing- original draft, review and editing, visualization.

Jonathan Rosenberg- conceptualization, supervision, writing- review and editing.

All authors have agreed on the journal to which the article will be submitted, reviewed, and agreed on all versions of the article before submission, during revision, the final version accepted for publication, and any significant changes introduced at the proofing stage. All authors agree to take responsibility and be accountable for the contents of the article and to share responsibility to resolve any questions raised about the accuracy or integrity of the published work.

Disclosure statement

Jonathan Rosenberg reports consultant/ advisory board fees for Astellas, AstraZeneca, Aktis, Bayer, BMS, Boehringer Ingelheim, Generate Biomedicines, Gilead, Loxo at Lilly, Merck, Samsung Bioepis, Seagen/Pfizer, Tyra Biosciences; grant/research support for Roche/Genentech; AstraZeneca, Seagen/Pfizer, Astellas, Acrivon, Loxo at Lilly, Bayer; and honorarium for Pfizer. Prior relationships (not active) include consultant role for Aadi Bioscience, EMD Serono, Hengrui, IMVAX, Janssen Oncology, Roche/ Genentech; and honorarium for EMD-Serono.

The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.