Impact of immunotherapy time-of-day infusion on survival and immunologic correlates in patients with metastatic renal cell carcinoma: a multicenter cohort analysis

Abstract

Background

Recent studies have demonstrated that earlier time-of-day infusion of immune checkpoint inhibitors (ICIs) is associated with longer progression-free survival (PFS) and overall survival (OS) among patients with metastatic melanoma and non-small cell lung cancer. These data are in line with growing preclinical evidence that the adaptive immune response may be more effectively stimulated earlier in the day. We sought to determine the impact of time-of-day ICI infusions on outcomes among patients with metastatic renal cell carcinoma (mRCC).

Methods

The treatment records of all patients with stage IV RCC who began ICI therapy within a multicenter academic hospital system between 2015 and 2020 were reviewed. The associations between the proportion of ICI infusions administered prior to noon (denoting morning infusions) and PFS and OS were evaluated using univariate and multivariable Cox proportional hazards regression.

Results

In this study, 201 patients with mRCC (28% women) received ICIs and were followed over a median of 18 months (IQR 5–30). The median age at the time of ICI initiation was 63 years (IQR 56–70). 101 patients (50%) received ≥20% of their ICI infusions prior to noon (Group A) and 100 patients (50%) received <20% of infusions prior to noon (Group B). Across the two comparison groups, initial ICI agents consisted of nivolumab (58%), nivolumab plus ipilimumab (34%), and pembrolizumab (8%). On univariate analysis, patients in Group A had longer PFS and OS compared with those in Group B (PFS HR 0.67, 95% CI 0.48 to 0.94, P_univar=0.020; OS HR 0.57, 95% CI 0.34 to 0.95, P_univar=0.033). These significant findings persisted following multivariable adjustment for age, sex, performance status, International Metastatic RCC Database Consortium risk score, pretreatment lactate dehydrogenase, histology, and presence of bone, brain, and liver metastases (PFS HR 0.70, 95% CI 0.50 to 0.98, P_multivar=0.040; OS HR 0.57, 95% CI 0.33 to 0.98, P_multivar=0.043).

Conclusions

Patients with mRCC may benefit from earlier time-of-day receipt of ICIs. Our findings are consistent with established mechanisms of chrono-immunology, as well as with preceding analogous studies in melanoma and lung cancer. Additional prospective randomized trials are warranted.

WHAT IS ALREADY KNOWN ON THIS TOPIC

• Prior studies have shown that circadian rhythm may impact the efficacy of immunotherapy in treating cancers.

WHAT THIS STUDY ADDS

• In this study we show that the timing of immunotherapy infusions is significantly associated with progression-free survival and overall survival in patients with metastatic renal cell carcinoma.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

• The implications of this study merit larger-scale prospective randomized trials for additional validation.

Introduction

Cancer of the kidney and renal pelvis accounts for approximately 4.2% of all cancer incidence and 2.4% of all cancer deaths within the USA.1 Renal cell carcinoma (RCC), the most common cancer of the kidney, is generally managed surgically for early-stage disease and metastatic cases where resection is possible. While systemic therapies are a key component of managing advanced-stage disease, there are wide variabilities in treatment response.2 Innovative strategies are needed for improvement.

Circadian control of the immune system was established several decades ago with pioneering work showing that circulating lymphocyte counts fluctuate throughout the day in healthy adults.3 Subsequent studies have elegantly revealed that the secretion profile of multiple proinflammatory cytokines displays a circadian rhythm and this rhythmicity in cytokine production can have a profound effect on cancer pathogenesis and response to treatment.4–10 Similarly, many studies have evaluated the impact of circadian physiology on chemotherapy toxicity. Phase 1 studies as early as 1990 have shown that for patients with breast cancer, hepatocellular carcinoma, and cholangiocarcinoma, synchronizing oxaliplatin with the host circadian rhythm leads to a decreased incidence of neutropenia and peripheral paresthesia while elevating mean and maximum tolerated dose.11 This seminal work then motivated prospective randomized assessment of chronotherapy for colorectal cancer.12 13 Analogously, the effect of the circadian rhythm on therapeutic cytokine infusions has also been examined.14–16

Immunotherapy has emerged as the first-line standard of care for numerous oncologic settings.17 18 We previously demonstrated that earlier time-of-day administration of immune checkpoint inhibitors (ICIs) is significantly associated with longer progression-free survival (PFS) and overall survival (OS) among patients with metastatic melanoma.19 ICIs have also become a cornerstone of metastatic RCC (mRCC) management, though the association between time-of-day of ICI infusions and outcomes in mRCC remains unclear and warrants further investigation.

Methods

Patient population

In this multicenter cohort study, we analyzed the de-identified individual-level clinicopathologic and treatment data of all adults (age ≥18 years) diagnosed with mRCC who received ICI infusions (pembrolizumab, nivolumab, or dual checkpoint blockade with ipilimumab and nivolumab) across the academic medical centers comprising Winship Cancer Institute of Emory University (Atlanta, Georgia, USA) between 2015 and 2020. Information on vital status was available for patients who died before or on December 31, 2021. Patients who received any ICI infusions outside of Winship Cancer Institute were excluded from the analysis (figure 1).

Figure 1.

Study schema. ICI, immune checkpoint inhibitor; mRCC, metastatic renal cell carcinoma.

Primary independent variable

From our institution’s infusion clinic central records, we downloaded the timestamps of ICI infusions administered to patients for the treatment of primary renal malignancies. Exclusion of patients with histologies other than RCC or non-metastatic disease was performed by manual inspection of the electronic medical records for corresponding patients. Timestamps were automatically generated when infusion clinic staff had fulfilled a physician order and initiated ICI infusion. Timestamps were recorded in Eastern Standard Time. For combination ICI treatments (ie, dual checkpoint blockade with ipilimumab and nivolumab), the infusion start time of the first administered agent was established as the timestamp of record.

Patients in this study were partitioned into those who received at least 20% of their ICI infusions prior to noon (Group A) and those who received less than 20% of their ICI infusions prior to noon (Group B). Noon was chosen as the time-of-day threshold of interest as it is the nearest hour to the median infusion time among all patients and aligns with precedence set by previous circadian rhythm studies of ICIs for melanoma and lung cancer, as well as vaccination for infectious disease.20–23 The proportion threshold of 20% was set to optimize the balance between comparison group sample sizes (table 1).

Table 1.

Patient characteristics

	≥20% ICI infusions prior to noon N=101 (%)	<20% ICI infusions prior to noon N=100 (%)	P value
Sex			0.10
Female	22 (22)	33 (33)
Male	79 (78)	67 (67)
Age at ICI initiation			0.08
≤50	16 (16)	17 (17)
51–60	17 (17)	32 (32)
61–70	42 (41)	28 (28)
71–80	22 (22)	17 (17)
≥81	4 (4)	6 (6)
ECOG			0.86
0	45 (44)	41 (41)
1	39 (39)	40 (40)
≥2	17 (17)	19 (19)
Statin use	34 (34)	38 (38)	0.62
IMDC risk score			0.37
0 (favorable)	10 (10)	7 (7)
1–2 (intermediate)	55 (54)	48 (48)
≥3 (poor)	36 (36)	45 (45)
RCC histology			0.74
Clear cell	74 (73)	68 (68)
Papillary	5 (5)	6 (6)
Chromophobe	2 (2)	1 (1)
Collecting duct	3 (3)	1 (1)
Sarcomatoid	1 (1)	2 (2)
Mixed histologies of the above	7 (7)	12 (12)
With sarcomatoid features	1 (1)	3 (3)
With chromophobe features	0 (0)	0 (0)
Other (eg, eosinophilic, Xp11 translocation, poorly differentiated)	9 (9)	10 (10)
Pretreatment LDH			0.51
Normal	52 (51)	54 (54)
Elevated	12 (12)	16 (16)
Unknown	37 (37)	30 (30)
Bone metastasis	34 (34)	28 (28)	0.48
Brain metastasis	9 (9)	18 (18)	0.09
Liver metastasis	28 (28)	25 (25)	0.78
First-line therapy included ICI	44 (44)	32 (32)	0.12
Initial ICI regimen			0.57
Nivolumab	43 (43)	53 (53)
Nivolumab+TKI	11 (11)	10 (10)
Pembrolizumab	3 (3)	3 (3)
Pembrolizumab+TKI	4 (4)	5 (5)
Dual nivolumab/ipilimumab	40 (40)	29 (29)
ICI ever received*
Nivolumab	54 (53)	63 (63)	0.22
Pembrolizumab	14 (14)	8 (8)	0.27
Dual nivolumab/ipilimumab	40 (40)	30 (40)	0.20
Non-ICI systemic therapies ever received*
Cabozantinib	47 (46)	39 (39)	0.35
Pazopanib	29 (29)	31 (31)	0.84
Sunitinib	12 (12)	22 (22)	0.08
Everolimus	19 (19)	13 (13)	0.35
Lenvatinib	16 (16)	6 (6)	0.05
Axitinib	9 (9)	7 (7)	0.81

*Percentages do not add up to 100 because some patients received multiple ICI and non-ICI systemic therapy regimens.

ECOG, Eastern Cooperative Oncology Group performance status; ICI, immune checkpoint inhibitor; IMDC, International Metastatic RCC Database Consortium; LDH, lactate dehyrogenase; RCC, renal cell carcinoma; TKI, tyrosine kinase inhibitor.

Clinical and translational outcomes

The primary endpoints of this study are PFS and OS. PFS was defined as time to progression per the immune-modified Response Evaluation Criteria in Solid Tumors (RECIST) criteria (imRECIST).24 OS was defined as time to death from any cause. Both PFS and OS were indexed from the date of the first ICI infusion. Patients lost to follow-up were censored at the time of last known contact. A subset of patients in the present study had also enrolled in our previously reported study of ICI treatment response biomarkers in RCC; a burst of HLA-DR+CD38+CD8+ T cells in the peripheral blood following two cycles of immunotherapy was found to be associated with objective response.19 25 26 For further immunologic corroboration of the present study, we stratified fold change (FC) of HLA-DR+CD38+CD8+ T cells by time-of-day ICI infusion group status for these overlapping patients.

Covariates

We also ascertained clinicopathologic characteristics for every patient, reflecting pre-immunotherapy baseline and factors with potential influence on infusion time-of-day scheduling or the outcomes of interest. These characteristics include sex, age, ECOG (Eastern Cooperative Oncology Group) performance status, statin use, RCC histology, pretreatment lactate dehydrogenase (LDH), International Metastatic RCC Database Consortium (IMDC) risk score (composite score derived from baseline hemoglobin, corrected calcium, circulating neutrophils, circulating platelets, Karnofsky performance status), presence of bone, brain, and liver metastases, history of ICIs received, and history of non-ICI systemic therapies received.27–30 History of corticosteroid use and tumor Programmed Death-Ligand 1 (PD-L1) status were not considered; they have not consistently demonstrated influence on outcomes in mRCC, in contrast to metastatic melanoma and non-small cell lung cancer (NSCLC).31–35

Statistical analysis

Patient clinicopathologic characteristics in Group A and Group B were compared using the χ² test for categorical variables and the Kruskal-Wallis test for continuous variables involving medians (table 1). The objective response rate was computed as the fraction of patients in each group who achieved a complete response (CR) or partial response (PR) per imRECIST, and compared using the χ² test.24 PFS and OS were estimated using the Kaplan-Meier method. The associations between clinicopathologic characteristics and PFS and OS were computed using univariate Cox proportional hazards regression.

PFS and OS of patients in Group A were compared with those in Group B using Cox proportional hazards regression without and with multivariable adjustment for age, sex, and other clinically relevant and statistically significant covariates from univariate analyses of PFS and OS (table 2). Pretreatment LDH was the only variable with missing values (table 1); for regressions, this continuous variable was converted into a binary indicator coded as either elevated, or normal or unknown.

Table 2.

Cox proportional hazards regression results

	Univariate				Multivariable
	PFS		OS		PFS		OS
	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value
≥20% ICI infusions prior to noon	0.67 (0.48 to 0.94)	0.020	0.57 (0.34 to 0.95)	0.033	0.70 (0.50 to 0.98)	0.040	0.57 (0.33 to 0.98)	0.043
Age (per year)	1.00 (0.99 to 1.02)	0.543	1.00 (0.98 to 1.02)	0.910	1.01 (0.99 to 1.02)	0.339	1.01 (0.98 to 1.03)	0.651
Male (vs female)	0.82 (0.57 to 1.19)	0.300	0.97 (0.55 to 1.72)	0.928	0.85 (0.58 to 1.26)	0.421	1.00 (0.55 to 1.83)	0.990
ECOG≥2 (vs <2)	1.98 (1.30 to 3.03)	0.002	2.91 (1.54 to 5.50)	0.001	1.43 (0.88 to 2.34)	0.153	1.93 (0.92 to 4.02)	0.081
Statin use	0.88 (0.62 to 1.25)	0.475	0.91 (0.53 to 1.56)	0.721
Elevated LDH	1.89 (1.17 to 3.05)	0.009	3.82 (2.03 to 7.22)	<0.001	1.31 (0.77 to 2.22)	0.327	2.28 (1.10 to 4.69)	0.026
IMDC score (per unit increase)	1.33 (1.16 to 1.51)	<0.001	1.51 (1.22 to 1.86)	<0.001	1.26 (1.09 to 1.47)	0.002	1.33 (1.06 to 1.67)	0.016
Histology
Clear cell	0.76 (0.53 to 1.10)	0.141	0.50 (0.29 to 0.86)	0.012	1.03 (0.69 to 1.54)	0.876	0.67 (0.37 to 1.21)	0.182
Any chromophobe features	0.73 (0.18 to 2.94)	0.654	1.08 (0.15 to 7.82)	0.939
Any sarcomatoid features	1.04 (0.42 to 2.54)	0.938	1.70 (0.52 to 5.48)	0.378
Bone metastasis	1.17 (0.82 to 1.68)	0.384	1.31 (0.76 to 2.23)	0.329	1.01 (0.69 to 1.48)	0.953	1.13 (0.63 to 2.06)	0.677
Brain metastasis	1.13 (0.67 to 1.91)	0.647	0.68 (0.27 to 1.70)	0.408	0.97 (0.56 to 1.68)	0.908	0.60 (0.23 to 1.55)	0.290
Liver metastasis	1.42 (0.98 to 2.06)	0.064	2.19 (1.28 to 3.75)	0.004	1.41 (0.96 to 2.08)	0.078	1.92 (1.08 to 3.41)	0.027
First-line therapy included ICI	0.82 (0.57 to 1.17)	0.279	0.64 (0.35 to 1.15)	0.136
Initial ICI regimen
Dual ipi/nivo	(Reference)
Nivolumab	1.01 (0.70 to 1.47)	0.954	1.30 (0.71 to 2.38)	0.397
Nivolumab+TKI	0.68 (0.34 to 1.34)	0.262	1.21 (0.45 to 3.29)	0.706
Pembrolizumab	0.76 (0.27 to 2.12)	0.603	0.73 (0.10 to 5.47)	0.757
Pembrolizumab+TKI	1.01 (0.43 to 2.36)	0.986	2.29 (0.67 to 7.84)	0.188
Ever received
Nivolumab	0.97 (0.69 to 1.37)	0.856	1.20 (0.70 to 2.09)	0.506
Pembrolizumab	0.78 (0.46 to 1.34)	0.377	0.84 (0.36 to 1.97)	0.693
Dual ipi/nivo	1.07 (0.75 to 1.52)	0.724	0.74 (0.42 to 1.32)	0.314
Cabozantinib	1.31 (0.93 to 1.84)	0.119	1.37 (0.81 to 2.32)	0.241
Pazopanib	1.15 (0.81 to 1.65)	0.435	0.94 (0.54 to 1.64)	0.827
Sunitinib	0.93 (0.59 to 1.47)	0.752	1.16 (0.61 to 2.23)	0.647
Everolimus	1.32 (0.87 to 2.00)	0.191	1.43 (0.79 to 2.59)	0.232
Lenvatinib	1.25 (0.77 to 2.03)	0.368	0.89 (0.42 to 1.88)	0.758
Axitinib	1.56 (0.89 to 2.72)	0.118	0.67 (0.21 to 2.14)	0.495

ECOG, Eastern Cooperative Oncology Group performance status; ICI, immune checkpoint inhibitor; IMDC, International Metastatic renal cell carcinoma Database Consortium; ipi, ipilimumab; LDH, lactate dehydrogenase; nivo, nivolumab; OS, overall survival; PFS, progression-free survival; TKI, tyrosine kinase inhibitor.

For the patients in this study who had consented to provide peripheral blood before and after two cycles of immunotherapy, the FCs in HLA-DR+CD38+CD8+ T cells were computed as previously reported.25 Here, we assessed the distribution of patients who experienced >1.5 FC of HLA-DR+CD38+CD8+ T cells across Groups A and B as well as across objective response categories of CR, PR, stable disease, and progression of disease per imRECIST.36–38 The log₂(FC) of HLA-DR+CD38+CD8+ T cells was also compared between patients who initiated ICIs in the first line versus subsequent lines of systemic therapy using t-test.

Results

From initial Food and Drug Administration approval of immunotherapy for mRCC on November 23, 2015, to December 31, 2020, we identified 201 patients with confirmed mRCC, 55 (27%) were women and 146 (73%) were men with the median age at the time of ICI initiation of 63 years (IQR 56–70 years). The majority of patients had clear cell histology (142 patients, 71%), intermediate risk IMDC score (103 patients, 51%), and ECOG<2 (165 patients, 82%). In total, these patients received 2163 infusions of ipilimumab, nivolumab, and pembrolizumab, and were followed for a median of 18 months (IQR 5–30).

101 patients (50%) received ≥20% of their infusions prior to noon (Group A) and 100 patients (50%) received <20% of their infusions prior to noon (Group B). The percentage of patients who received at least one of their initial two infusions prior to noon was 64% in Group A and 7% in Group B (p<0.0001). Across the two comparison groups, initial ICI agents consisted of nivolumab (58%), dual ipilimumab/nivolumab (34%), and pembrolizumab (8%). Other non-ICI systemic therapies are outlined in table 1. Importantly, Group A and Group B were well-balanced for all reported patient characteristics (table 1).

Patients in Group A achieved a higher objective response rate than those in Group B (34% (34 of 101) vs 21% (21 of 100), p=0.044). Poor performance status (ECOG≥2), higher IMDC score, and elevated LDH were associated with worse PFS and worse OS. Administration of ICI in the first-line setting and choice of initial ICI did not impact outcomes (table 2). On univariate analysis, patients in Group A had longer PFS and OS compared with those in Group B (figure 2; PFS HR 0.67, 95% CI 0.48 to 0.94, P_univar=0.020; OS HR 0.57, 95% CI 0.34 to 0.95, P_univar=0.033). These significant findings persisted following multivariable adjustment for age, sex, ECOG, IMDC risk score, pretreatment LDH, RCC histology, and presence of bone, brain, and liver metastases (table 2; PFS HR 0.70, 95% CI 0.50 to 0.98, P_multivar=0.040; OS HR 0.57, 95% CI 0.33 to 0.98, P_multivar=0.043). In a multivariable sensitivity analysis of varying thresholds for time-of-day ICI infusion in the vicinity of noon and fraction of ICI infusions in the vicinity of 20%, OS HRs remained stable (online supplemental table 1).

Figure 2.

Kaplan-Meier plots of progression-free survival (A) and overall survival (B) for Group A patients (≥20% infusions before noon) and Group B patients (<20% infusions before noon).

There were also no anomalous subgroup deviations in OS association. The effect size and direction of associations between time-of-day ICI infusions and OS stood congruent across clinicopathologic subgroups (figure 3). Of note, patients who were older in age, better in performance status, more favorable in IMDC risk, and with liver metastasis exhibited more pronounced associations between time-of-day ICI infusions and OS.

Figure 3.

Forest plot of overall survival HRs across clinicopathological subgroups. For the few patients who received lenvatinib, one comparison group had zero events and the HR could not be confidently estimated using Cox proportional hazards regression. ECOG, Eastern Cooperative Oncology Group performance status; ICI, immune checkpoint inhibitor; IMDC, International Metastatic RCC Database Consortium; LDH, lactate dehydrogenase; RCC, renal cell carcinoma.

In our previous study, we showed that for patients with mRCC receiving ICIs, the FC in peripheral blood HLA-DR+CD38+CD8+ T cells correlates with clinical response.25 39 16 patients from this prior translational immunologic analysis had relevant time-of-day metrics recorded. Of these, 6 patients belonged to Group A and 10 patients belonged to Group B. All patients from Group A (100%) demonstrated >1.5 FC in HLA-DR+CD38+CD8+ T cells in the peripheral blood compared with only 60% from Group B with a trend towards significance (p=0.074, figure 4A). For patients who had >1.5 FC in HLA-DR+CD38+ CD8+ T cells in the peripheral blood, only 33% had progressive disease while 50% of those with ≤1.5 FC had progressive disease (figure 4B). The log₂(FC) of HLA-DR+CD38+CD8+ T cells were similar between patients who did (n=4) and did not (n=12) initiate ICIs in the first-line setting (mean of 1.36 vs 1.30, p=0.962). Collectively, these data support the hypothesis that earlier time-of-day ICI infusions may induce a more robust systemic immune response that confers improved patient outcomes.

Figure 4.

(A) Fold change in HLA-DR+CD38+CD8+ T cells following two cycles of immunotherapy across Group A patients (≥20% infusions before noon) and Group B patients (<20% infusions before noon). (B) Clinical response per immune-modified Response Evaluation Criteria in Solid Tumors. CR, complete response; PD, progression of disease; PR, partial response; SD, stable disease.

Discussion

Among patients with mRCC in this multicenter cohort study, receiving at least 20% of ICI infusions prior to noon was associated with longer PFS and OS in both univariate and multivariable analysis. Comparison groups were balanced in size and clinicopathologic characteristics.

Our findings suggest that preferential earlier infusions of ICIs may improve both treatment efficacy and survival through complex time-of-day dependent interactions between checkpoint inhibition and the rhythmic adaptive immune system.40 These results are consistent with our previous studies of ICI administration timing for metastatic melanoma and NSCLC.19 21 It is also important to highlight that 64% of patients in Group A received at least one of their initial two ICI infusions prior to noon, compared with only 7% of Group B. Time-of-day administration of the initial two infusions may be exceptionally important for antitumor immunologic stimulation, as corroborated by a recent prospective clinical trial which demonstrated that for patients with advanced melanoma receiving nivolumab plus ipilimumab, treatment efficacy and toxicity were primarily driven by the initial two infusions.26 41

Additionally, we investigated T-cell response in the peripheral blood for both Group A and Group B patients. A greater rise in HLA-DR+CD38+CD8+ T cells following the initial two cycles of immunotherapy correlated with achievement of objective response.25 While only 16 patients with mRCC of that previous study overlap with the present study, 100% of Group A patients had >1.5 FC in peripheral HLA-DR+CD38+CD8+ T cells following two ICI cycles while 60% of Group B did. A greater than 1.5-fold increase in this proliferating CD8+ T cell population has been identified as a threshold for CD8+ T cell response following anti-Programmed Cell Death Protein 1 (PD-1) therapy.37 This threshold was selected based on our institution’s prior study on patients with NSCLC treated with ICI in whom the median CD8+ T cell response was >1.5-fold.37

Our clinical data are supported by accumulating translational evidence from murine models. Both B and T-cell subsets have been shown to oscillate in the blood, lymph, and lymph nodes in a circadian-dependent manner.42 43 This oscillation depends on the cyclical expression of pro-migratory chemokines and receptors, and these factors are expressed in a molecular clock-controlled, cell-autonomous manner.44 Multiple groups have demonstrated more robust induction of autoimmune disease and greater antigen-specific T-cell responses when vaccines are administered during peak time-of-day nodal lymphocyte cellularity.22 42 43 This suggests that the anatomic localization of CD8+ T cells at the time of stimulation may influence their magnitude of response. In the context of tumor biology, it has now been shown that the time-of-day tumors are inoculated into mice influences the magnitude of the immune-mediated antitumor response.23 Another study showed that rhythmic changes in PD-1 expression by tumor-infiltrating macrophages modulate response to PD-1 inhibition.45 As ongoing preclinical studies investigate underlying mechanisms in more detail, the present clinical study adds to a growing body of literature that suggests a circadian dependence of the global and tumor-specific immune response.

There are several limitations to this study. First, it is retrospective and carries the potential for confounding. However, we performed a comprehensive multivariable analysis with adjustment for age, sex, ECOG, IMDC risk score, pretreatment LDH, RCC histology, and presence of bone, brain, and liver metastases, through which PFS and OS maintained statistical significance.30 Second, infusion times varied widely across patients and for each patient, due to the flexibility given to patients to arrange their own infusion schedules. This flexibility invoked timing stratification to rely on proportions rather than fixed time intervals for infusion. A prospective randomized trial that directly assigns patients to specific time blocks for every infusion would help better determine the true effect of time-of-day ICI treatment on efficacy. Serial blood draws over the course of ICI treatment would also be valuable to correlate immunologic response with clinical outcomes.

Immunotherapy is the standard of care for many malignancies including mRCC. While the interplay between circadian rhythm and immunotherapy remains an area of active investigation, the findings presented herein justify further development of randomized studies that more concretely establish time-of-day optimization strategies for ICI management of patients with mRCC.

Data availability statement

Data are available upon reasonable request.

Ethics statements

Patient consent for publication

Not applicable.

Ethics approval

Not applicable.