Abstract
Background: In first/second generation EGFR-TKIs, strong PD-L1 expression contributes to primary resistance, significantly affecting patient prognosis. The relationship between PD-L1 expression levels and third-generation TKIs remains unclear.
Methods: This study analyzed advanced NSCLC who received third-generation EGFR-TKIs as first-line systemic therapy from March 2019 to June 2022. The EGFR and PD-L1 status of the patients was also assessed.
Results: Overall, 150 patients were included in this study. PD-L1 expression was negative (PD-L1 tumor proportion score <1%) in 89 cases, weak (1–49%) in 42 cases, and strong (≥50%) in 19 cases. mPFS for patients with negative, weak and strong PD-L1 expressions was 23.60, 26.12 and 16.60 months, respectively. The mPFS for strong PD-L1 expression was significantly shorter than that for with weak PD-L1 expression but was not associated with negativity. The same conclusions were shown in subgroup analyses of mutation types and TKI kinds. In addition, Relative to PD-L1-negative patients, resistance to TKIs may be associated with early progression for patients with strong PD-L1 expression.
Conclusion: PD-L1 expression in tumor cells influenced the clinical outcomes of patients with advanced NSCLC treated with third-generation EGFR-TKIs. Stronger PD-L1 expression in TKIs-treated patients with advanced first-line EGFR-mutated NSCLC was associated with worse PFS.
Keywords: : EGFR mutations, non-small cell lung cancer, programmed death ligand 1, tyrosine kinase inhibitors
Plain language summary
Article highlights.
This retrospective study showed that strong PD-L1 expression predicts poor response to EGFR-TKIs therapy in patients with EGFR-mutated NSCLC.
PD-L1 expression and the efficacy of three-generation TKIs in which the cut-off is 1 is not a better demarcator.
PD-L1 expression can be used as a reliable biomarker for EGFR-TKI therapy to predict patient survival.
PD-L1, as a biomarker for evaluating prognosis, will not change due to mutation and TKI types.
PD-L1, as a biomarker for evaluating prognosis, is still applicable in non-classical mutations of EGFR.
High expression of PD-L1 may be a predictive indicator for primary drug resistance in targeted therapy.
The relationship between PD-L1 expression combined with gene co-mutation and the prognosis of third-generation TKI can be a future research direction.
Exploring effective biomarkers to enrich the beneficiary population may be an important research direction for optimizing the application of immunotherapy in EGFR-TKIs-resistant NSCLC.
1. Introduction
Lung cancer is the main contributor to cancer-related health issues, constituting approximately 80% of non-small cell lung cancer (NSCLC). Among NSCLC cases, adenocarcinoma comprises about 40%, followed by squamous cell carcinoma, which accounts for approximately 25% [1,2]. Epidermal growth factor receptor (EGFR) mutations, as the main driver mutation, account for approximately 30% of NSCLC cases and 50% of lung adenocarcinoma cases [3–5]. The treatment of EGFR-positive advanced NSCLC has transitioned from the era of chemotherapy to the era of targeted therapy, with a three-step jump in survival. First-generation EGFR Tyrosine Kinase Inhibitors (TKIs) (Gefitinib, Erlotinib, Icotinib) achieved median progression-free survival (mPFS) of 9.2–13.1 months, which was significantly prolonged compared with previous standard chemotherapy (mPFS 4.6–5.2 months) [6–10]. Second-generation EGFR TKIs (afatinib and dacomitinib) mPFS reached 11–14.7 months, but the incidence of adverse events was also significantly increased [11,12]. Third-generation EGFR TKIs (osimertinib, almonertinib, furmonertinib and befotertinib) have better efficacy than first- and second-generation ones, with mPFS of 17.8–22.1 months, and a reduced incidence of adverse effects compared with the second-generation ones [13–16]. Currently, Third-generation TKIs represent the established standard of care for advanced EGFR-positive lung adenocarcinoma [14,16,17].
PD-L1 is a ligand for programmed cell death protein 1 (PD-1), and the combination of PD-1 and PD-L1 transmits negative regulatory signals to T cells. This interaction impedes T cells from recognizing cancer cells, leading to the tumor's “immune escape” [18,19]. The expression level of PD-L1 is an important predictor of the treatment efficacy of immune checkpoint inhibitors. However, in patients undergoing first/second generation EGFR-TKIs treatment, high PD-L1 expression has been linked to primary resistance, significantly shortening the mPFS and median overall survival (mOS) [20–24]. Many studies have explored the association between PD-L1 expression levels and EGFR-TKIs clinical efficacy, but few have focused on third-generation EGFR-TKIs; therefore, there are no clear, conclusive findings on the correlation between PD-L1 expression and third-generation TKI efficacy.
This retrospective study aimed to further define the relationship between PD-L1 expression levels and the efficacy of first-line administration of third-generation EGFR TKIs in patients with advanced EGFR-mutant lung adenocarcinoma.
2. Patients & methods
2.1. Study design & patients
This retrospective study analyzed patients with advanced NSCLC who received third-generation EGFR-TKIs as first-line systemic therapy between March 2019 and June 2022 at the Shandong Cancer Hospital and Institute, affiliated with Shandong First Medical University (Figure 1). Demographic characteristics and clinical data, including age, gender, smoking status, Eastern Cooperative Oncology Group Physical Status (ECOG PS), time to diagnosis, time to progression, tumor type, baseline EGFR mutation status and EGFR-TKIs treatment type, were extracted from electronic medical records. This study was approved by the Ethical Review Committee of the Affiliated Cancer Hospital of Shandong First Medical University (Ethical approval number: SDTHEC2024001026) and was conducted in accordance with the Declaration of Helsinki.
Figure 1.
CONSORT diagram.
EGFR: Epidermal growth factor receptor; NSCLC: Non-small cell lung cancer; PD-L1: Programmed death-ligand 1; TKI: Tyrosine kinase inhibitor.
2.2. EGFR & PD-L1 evaluation
EGFR mutations were confirmed using amplification refractory mutation system fluorescence quantitative polymerase chain reaction in paraffin-embedded tissues. EGFR-sensitive mutations were those associated with EGFR-TKIs sensitivity, including exon 19 deletions and exon 21 L858R. PD-L1 expression levels were determined using the Dako LINK 48 detection system (Agilent Technologies, Santa Clara, CA, USA). The tumor PD-L1 expression status was evaluated by determining the tumor proportion score (TPS) using 22 C3 antibodies. The TPS scores of the tumor sections were independently evaluated by at least two senior pathologists, categorizing PD-L1 expression into three groups (<1%, negative expression; 1–49%, weak expression; ≥50%, strong expression) based on the TPS score.
2.3. Statistical analysis
Correlations between baseline characteristics and subgroups of tumor PD-L1 expression were analyzed by χ2 test or Fisher's exact test. PFS and OS were the primary end points of this study. PFS was defined as the time from the initiation of EGFR-TKIs treatment to the detection of disease progression or death from any cause. OS was defined as the time from the initiation of EGFR-TKIs therapy to death from any cause. PFS and OS were evaluated using the Kaplan–Meier method. The log-rank test was used to compare differences in survival curves between the two groups. Multivariate analysis, incorporating age, sex, smoking history, ECOG PS, brain metastasis status at diagnosis and PD-L1 expression, was performed using logistic regression models. Statistical analyses were performed with SPSS statistical software version 26.0 (IBM Corporation, Armonk, NY, USA) and Prism software version 8.0.2 (GraphPad Software, Boston, MA, USA). All reported p-values were two-sided with a 95% confidence interval (95% CI), and statistical significance was set at p ≤ 0.05.
3. Results
3.1. Characterization of PD-L1 expression in EGFR-mutated NSCLC
A total of 150 patients who received third-generation EGFR-TKIs as first-line systemic therapy for advanced NSCLC between March 2019 and June 2022 at the Affiliated Cancer Hospital of Shandong First Medical University were enrolled in this study. The screening flowchart is shown in Figure 1. The demographic and clinical characteristics of the patients with EGFR mutations are presented in Table 1. The median age was 61 years (range 34–92 years), 92 (61.33%) patients were female, 122 (81.33%) were never-smokers, 141 (94%) had an ECOG PS performance status <2 and 145 (96.67) were pathologically diagnosed with adenocarcinoma. Furthermore, 81 (54%) patients had an exon 19 deletion, 69 (46%) had an exon 21 L858R mutation, 98 (65.33%) were treated with osimertinib and 52 (34.66%) were treated with aumolertinib. Baseline brain, bone and liver metastases were seen in 67 (44.67%), 74 (49.33 %) and 23 (15.33 %) patients, respectively.
Table 1.
Baseline characteristics of patients.
| Characteristic | Number of patients (%) |
|---|---|
| Age(years), n (%) | |
| <65 | 95 (63.33) |
| ≥65 | 55 (36.67) |
| median (range) | 61 (34–92) |
| Gender, n (%) | |
| Female | 92 (61.33) |
| Male | 58 (38.67) |
| Smoking history, n (%) | |
| Never smoker | 122 (81.33) |
| Current/former smoker | 28 (18.67) |
| ECOG PS, n (%) | |
| <2 | 141 (94.00) |
| ≥2 | 9 (6.00) |
| Pathological type, n (%) | |
| adenocarcinoma | 145 (96.67) |
| Other | 5 (3.33) |
| EGFR mutation, n (%) | |
| Exon 19 deletion | 81 (54.00) |
| Exon 21 L858R | 69 (46.00) |
| First-line three generations EGFR-TKIs, n (%) | |
| Osimertinib | 98 (65.33) |
| Almonertinib | 52 (34.66) |
| Brain metastases at diagnosis, n (%) | |
| Metastasis | 67 (44.67) |
| No metastasis | 83 (55.33) |
| Bone metastases at diagnosis, n (%) | |
| Metastasis | 74 (49.33) |
| No metastasis | 76 (50.67) |
| liver metastases at diagnosis, n (%) | |
| Metastasis | 23 (15.33) |
| No metastasis | 127 (84.67) |
ECOG PS: Eastern cooperative oncology group performance status; EGFR: Epidermal growth factor receptor; TKI: Tyrosine kinase inhibitor.
Of the 150 patients, 89 (59.33%) were negative for PD-L1 expression (TPS <1%), 42 (28%) had weak expression (1–49%) and 19 (12.66%) had strong expression (≥50%). PD-L1 expression correlated with age, gender, ECOG PS and presence of brain, bone and liver metastases at diagnosis; however, the EGFR mutation type was irrelevant (Table 2).
Table 2.
Association between PD-L1 expression and clinicopathologic features.
| PD-L1 expression | Negative (TPS <1%) (n = 89) | Weak (TPS:1–49%) (n = 42) | Strong (TPS ≥ 50%) (n = 19) | p-value |
|---|---|---|---|---|
| Age (years),n (%) | 0.184 | |||
| <65 | 59 (66.29%) | 22 (52.38%) | 14 (73.68%) | |
| ≥65 | 30 (33.71%) | 20 (47.62%) | 5 (26.32%) | |
| Gender, n (%) | 0.268 | |||
| Female | 54 (60.67%) | 29 (69.05%) | 9 (47.37%) | |
| Male | 35 (39.33%) | 13 (30.95%) | 10 (52.63%) | |
| Smoking history, n (%) | 0.010 | |||
| Never smoker | 73 (82.02%) | 38 (90.48%) | 11 (57.89%) | |
| Current/former smoker | 16 (17.98%) | 4 (9.52%) | 8 (42.11%) | |
| ECOG PS, n (%) | 0.896 | |||
| <2 | 83 (93.26%) | 40 (95.24%) | 18 (94.74%) | |
| ≥2 | 6 (6.74%) | 2 (4.76%) | 1 (5.26%) | |
| EGFR mutation, n (%) | 0.923 | |||
| Exon 19 deletion | 48 (53.93%) | 22 (52.38%) | 11 (57.89%) | |
| Exon 21 L858R | 41 (46.07%) | 20 (47.62%) | 8 (42.11%) | |
| Brain metastases at diagnosis, n (%) | 0.643 | |||
| Metastasis | 37 (41.57%) | 21 (50.00%) | 9 (47.37%) | |
| No metastasis | 52 (58.43%) | 21 (50.00%) | 10 (52.63%) | |
| Bone metastases at diagnosis, n (%) | 0.146 | |||
| Metastasis | 49 (55.06%) | 19 (45.24%) | 6 (31.58%) | |
| No metastasis | 40 (44.94%) | 23 (54.76%) | 13 (68.42%) | |
| liver metastases at diagnosis, n (%) | 0.368 | |||
| Metastasis | 16 (17.98%) | 6 (14.29%) | 1 (5.26%) | |
| No metastasis | 73 (82.02%) | 36 (85.71%) | 18 (94.74%) |
ECOG PS: Eastern cooperative oncology group performance status; EGFR: Epidermal growth factor receptor; PD-L1: Programmed death-ligand 1; TPS: Tumor proportion score.
3.2. The relationship between PD-L1 expression & clinical prognosis
3.2.1. Overall population
The median follow-up for the entire cohort was 22.12 months (95% CI: 20.98–23.26 months), mPFS was 24.33 months, and mOS was not reached (Figure 2A). In addition, there was no significant difference in survival between the 19DEL and L858R patients (Supplementary Figure S1A & B). In the subgroup analysis, mPFS was 23.60 months (95% CI: 16.61–30.60 months) for patients with negative PD-L1 expression, 26.12 months (95% CI: 19.05–33.18 months) for patients with weak PD-L1 expression, and 16.60 months (95% CI: 6.55–26.64 months) for patients with strong PD-L1 expression (log-rank: negative vs. weak PD-L1 expression, p = 0.103; negative vs. strong PD-L1 expression, p = 0.103; weak vs. strong PD-L1 expression, p = 0.001) (Figure 2B). This shows that the PFS of patients with strong PD-L1 expression was significantly shorter than that of patients with weak PD-L1 expression but was unrelated to negativity. The mOS of all three kinds has not been reached, and there is no statistically significant difference among the three. The expression of PD-L1 does not impact OS (Figure 2C). This leads to the conclusion that strong expression of PD-L1 in patients with EGFR-mutant NSCLC is associated with a poorer prognosis in TKI-treated patients. Relative to PD-L1-negative patients, resistance to TKIs was associated with early progression for patients with strong PD-L1 expression.
Figure 2.
Kaplan–Meier graph of the overall population. (A) OS and PFS of the overall population. (B) Kaplan–Meier graph of PFS for negative versus weak versus strong in overall patients. (C) Kaplan–Meier graph of OS for negative versus weak versus strong in overall patients. (D) Kaplan–Meier graph of PFS for TPS <1% versus TPS ≥ 1% in overall patients. (E) Kaplan-Meier graph of PFS for TPS <25% versus TPS ≥ 25% in overall patients. (F) Kaplan–Meier graph of PFS for TPS <50% versus TPS ≥ 50% in overall patients.
CI: Confidence interval; HR: Hazard ratio; mOS: Median overall survival; mPFS: Median progression-free survival; NA: Not available; PD-L1: Programmed death-ligand 1; TPS: Tumor proportion score.
In this study, PD-L1 expression levels were stratified by TPS = 1, 25 and 50% for prognostic analysis. The mPFS for PD-L1 <1% vs. PD-L1 ≥1% was 23.60 months (95% CI: 16.61–30.60 months) and 24.40 months (95% CI: 22.44–26.35 months), respectively (p = 0.397) (Figure 2D). For PD-L1 <25% vs. PD-L1 ≥25%, mPFS was 24.40 months (95% CI: 21.51–27.28 months) and 16.89 months (95% CI: 6.87–26.92 months), respectively (p = 0.024) (Figure 2E). For PD-L1 <50% vs. PD-L1 ≥50%, mPFS was 25.49 months (95% CI: 22.90–28.08 months) and 16.60 months (95% CI: 6.55–26.64 months), respectively (p = 0.015) (Figure 2F). In summary, a cutoff of 1 is not superior for PD-L1 expression and the efficacy of third-generation TKIs. Higher PD-L1 expression in TKI-treated patients with advanced EGFR-mutant NSCLC was associated with a worse prognosis.
In the multivariate Cox regression model, PD-L1 expression remained a significant prognostic indicator of PFS when adjusted for age at diagnosis, sex, smoking history, ECOG PS, mutation type, TKI type, and brain, bone and liver metastasis status (hazard ratio (HR) for weak vs. strong PD-L1 expression, 0.382; 95% CI: 0.169–0.863, p = 0.021) (Table 3).
Table 3.
Multivariate analysis of clinicopathological features for progression-free survival.
| Characteristic | HR | 95% CI | p-value |
|---|---|---|---|
| Age (years) | |||
| <65 | Reference | ||
| ≥65 | 0.698 | 0.402–1.214 | 0.203 |
| Gender | |||
| Female | Reference | ||
| Male | 1.141 | 0.606–2.149 | 0.682 |
| Smoking history | |||
| Never smoker | Reference | ||
| Current/former smoker | 1.551 | 0.732–3.284 | 0.252 |
| ECOG PS | |||
| <2 | Reference | ||
| ≥2 | 0.690 | 0.285–1.670 | 0.410 |
| EGFR mutation | |||
| Exon 21 L858R | Reference | ||
| Exon 19 deletion | 0.776 | 0.474–1.272 | 0.315 |
| First-line three generations EGFR-TKIs | |||
| Osimertinib | Reference | ||
| Almonertinib | 0.994 | 0.553–1.610 | 0.831 |
| Brain metastases at diagnosis | |||
| No metastasis | Reference | ||
| Metastasis | 1.376 | 0.846–2.238 | 0.199 |
| Bone metastases at diagnosis | |||
| No metastasis | Reference | ||
| Metastasis | 1.331 | 0.806–2.197 | 0.264 |
| liver metastases at diagnosis | |||
| No metastasis | Reference | ||
| Metastasis | 1.768 | 0.948–3.299 | 0.07 |
| PD-L1 expression | |||
| Strong (≥50%) | Reference | ||
| Weak (1–49%) | 0.382 | 0.169–0.863 | 0.021 |
| Negative (<1%) | 0.576 | 0.292–1.136 | 0.111 |
CI: Confidence interval; ECOG PS: Eastern cooperative oncology group performance status; EGFR: Epidermal growth factor receptor; HR: Hazard ratio; PD-L1: Programmed death-ligand 1; TKI: Tyrosine kinase inhibitor.
3.2.2. 19DEL & 21L858R subgroups
We further analyzed the relationship between PD-L1 expression and clinical prognosis in the 19DEL and 21L858R subgroups. In the 19DEL subgroup analysis, the mPFS of negative, weak, and strong PD-L1 expression was 26.55 (95% CI 21.36–31.73 months), 33.52 (95% CI 22.03–45.01 months), and 16.60 months (95% CI 8.50–24.69 months), respectively. The three two-by-two P-values were negative vs. weak expression, P = 0.637), negative vs. strong expression, P = 0.095), and weak vs. strong expression, P = 0.047) (Figure 3A). In the 21L858R subgroup analysis, the mPFS for negative, weak, and strong PD-L1 expression was 17.06 (95% CI 8.46–25.66 months), 26.12 (95% CI 23.42–28.81 months), and 7.17 months (95% CI 0.00–23.12 months), respectively. The three two-by-two P-values were negative vs. weak expression, P = 0.047), negative vs. strong expression, P = 0.484), and weak vs. strong expression, P = 0.036) (Figure 3B). In summary, 19DEL and 21L858R patients with strong PD-L1 expression had significantly shorter PFS than those with weak PD-L1 expression, with negativity being an independent prognostic factor. No correlation with PD-L1 was observed for OS in both groups due to the short follow-up period (Supplementary Figure S2A & B).
Figure 3.
Kaplan–Meier graph of PFS for mutation type and TKIs type. (A) Kaplan–Meier graph of PFS for 19DEL patients. (B) Kaplan–Meier graph of PFS for L858R patients. (C) Kaplan–Meier graph of PFS for osimertinib patients. (D) Kaplan–Meier graph of PFS for almonertinib patients.
CI: Confidence interval; HR: Hazard ratio; mOS: Median overall survival; mPFS: Median progression-free survival; NA: Not available.
3.2.3. Osimertinib & almonertinib subgroups
We further analyzed the relationship between PD-L1 expression and clinical prognosis in the Osimertinib and Almonertinib subgroups. In the Osimertinib subgroup, mPFS for negative, weak and strong PD-L1 expression was 23.54 (95% CI: 18.52–34.57 months), 23.07 (95% CI: 19.54–30.21 months) and 16.60 months (95% CI: 5.52–27.99 months), respectively. The three two-by-two p values were negative vs. weak expression, p = 0.731), negative vs. strong expression, p = 0.032), and weak vs. strong expression, p = 0.096 (Figure 3C). In the Almonertinib subgroup, the mPFS for negative, weak and strong PD-L1 expression was 16.89 months (95% CI: 13.33–20.46 months), not achieved (NA) and 12.20 months, respectively. The p-values for the three comparisons were negative vs. weak expression, p = 0.002), negative vs. strong expression, p = 0.840), and weak vs. strong expression, p = 0.001) (Figure 3D). In summary, the PFS of patients with strong PD-L1 expression in the almonertinib subgroup was significantly shorter than that of patients with weak PD-L1 expression, with negativity being an independent prognostic factor. However, Osimertinib showed a similar trend, but the results were not statistically different, probably because of the small sample size. No correlation with PD-L1 was observed for OS in both groups due to the short follow-up period (Supplementary Figure S2C & D).
4. Discussion
Currently, the third-generation TKIs osimertinib, almonertinib and furmonertinib have a more optimized structure with increased efficacy and reduced toxicity compared with first-generation TKIs and have become the standard of care for first-line treatment of EGFR mutation-positive advanced NSCLC. The FLAURA, AENEAS and FURLONG studies have confirmed that the first-line application of third-generation TKIs achieved a significant benefit in PFS and OS compared with the 1st/2nd generation, with mPFS exceeding 20 months and mOS exceeding 33 months [14,16,17,25].
The correlation between PD-L1, a crucial immune checkpoint inhibitor efficacy predictor, and EGFR-TKI efficacy has received considerable attention. Previous studies in patients receiving first/second generation TKIs demonstrated that high PD-L1 expression leads to primary resistance and significantly shortens mPFS and mOS [20–22,24,26]. However, few such studies have been conducted, and no definitive conclusions have been drawn. Therefore, this study aimed to analyze the role of PD-L1 in patients with EGFR mutations receiving first-line treatment with third-generation TKIs. Our retrospective analysis showed that high PD-L1 expression was associated with poor PFS in patients with advanced NSCLC. To the best of our knowledge, this is the largest retrospective study to date on the correlation between PD-L1 expression and the efficacy of first-line third-generation TKI in advanced NSCLC. In the analysis of the FLAURA study, the Osimertinib arm exhibited an mPFS of 18.4 months with a 79% ORR in patients with advanced primary EGFR-mutated NSCLC with PD-L1 ≥1%. Conversely, PD-L1-negative patients showed an mPFS of 18.9 months with an 85% ORR [27]. We concluded that the clinical outcomes in advanced EGFR-mutant NSCLC were not affected by PD-L1 expression status [27,28].
However, the FLAURA authors did not analyze the impact of different PD-L1 expression levels on clinical efficacy. In our study, we similarly found that PD-L1 bounding to 1 was not a prognostic indicator for advanced EGFR-mutant NSCLC. In our study, mPFS was 23.60 months in patients with advanced primary EGFR-mutated NSCLC with PD-L1 ≥1% and 24.40 months in PD-L1-negative patients (p = 0.397). The mPFS for PD-L1 <25% vs. PD-L1 ≥25% was 24.40 months (95% CI: 21.51–27.28 months) and 16.89 months (95% CI: 6.87–26.92 months; p = 0.024). The mPFS for PD-L1 <50% vs. PD-L1 ≥50% was 25.49 months (95% CI: 22.90–28.08 months), and 16.60 months (95% CI: 6.55–26.64 months; p = 0.015). In a multicenter prospective clinical study utilizing Osimertinib, Yoshimura et al. showed that PFS was shorter in patients with strong PD-L1 expression than in those with weak expression + negative PD-L1 (mPFS: 5.0 vs. 17.4; p < 0.001) [29]. Similarly, Hsu et al. reached the same conclusion that patients with strong PD-L1 expression had shorter PFS and OS than patients with weak expression + negative PD-L1 (mPFS: 9.7 vs. 26.5; p = 0.009), (25.4 vs. NA; p = 0.021) [30]. In summary, for PD-L1 expression and the efficacy of three-generation TKIs, a cutoff value of 1 is not a better demarcation index. Patients with advanced NSCLC and high PD-L1 expression have a poorer prognosis after treatment with EGFR-TKIs. Differences were considered statistically significant.
Furthermore, in addition to 21L858R and 19DEL, approximately 10% of EGFR-positive NSCLCs are classified as non-classical mutations. Examples include G719X, L861Q, S768I and Exon20 insertions [31]. They have rarely been studied for their association with PD-L1 expression due to their low incidence. In a small sample of 49 patients with non-classical mutations, it was shown that 49.0% of patients carrying non-classical mutations had positive PD-L1 expression; this was significantly higher than that of the population of patients carrying classical mutations, which was 12.2% [32]. the PD-L1 expression-positive cohort had a shorter mOS than the PD-L1 expression-negative patients (15.2 vs 29.3 months, p = 0.006). Univariate and multifactorial statistical analyses showed statistical analyses indicated that positive PD-L1 expression was associated with poorer OS [32].
Preclinical studies have reported that EGFR activation induces PD-L1 expression, promoting immune escape. EGFR-TKIs significantly downregulate PD-L1 expression in EGFR-mutant NSCLC cells [33,34]. In addition to MET activation, EGFR mutations may upregulate PD-L1 expression through the p-ERK 1/2/p-c-Jun and JAK-STAT pathways, with MUC 16 mutation frequency associated with high PD-L1 expression [21,35,36]. Notably, activating the JAK-STAT pathway may play a role in primary resistance to EGFR-TKIs [21]. This may account for the relatively poor prognostic outcomes in patients with high PD-L1 expression.
Increasing clinical evidence suggests that high PD-L1 expression could predict primary resistance to targeted therapies. Some studies have hypothesized that higher PD-L1 expression in patients with NSCLC leads to poor prognosis for TKIs therapy through the tumor microenvironment. Although the mechanism is not fully understood, PD-L1 expression levels should be determined in clinical practice at initial diagnosis in patients with or without detectable driver gene variants. Subsequent immunotherapy after the failure of TKIs treatment may be a viable treatment option for patients with high PD-L1 expression. Further research is needed to focus on the optimal treatment strategies to screen and develop personalized and precise treatment plans for the high PD-L1-expressing population with driver variants.
The chemo-immunotherapy combined with or without antiangiogenic modality has now become the standard of care for treatment after resistance to targeted therapy. Biomarkers of immune resistance in back-line therapy are unknown. Causes of immune resistance involve defects in antigen presentation machinery, antigen loss, immunosuppression, aberrant inactivation of IFN-γ signaling and other immune checkpoint inhibitor effects [37]. Numerous possible biomarkers such as low expression of HLA-I APM-related genes, B2M loss, JAK1/2 inactivating mutations, PTEN deletion, abnormal activation of Wnt/β-catenin and IDO (indoleamine 2,3-dioxygenase) [38–44]. Exploring effective biomarkers to enrich the beneficiary population [33]may be an important research direction to optimize the use of immune-combination therapy in EGFR-TKIs-resistant NSCLC.
Our study had some limitations. First, compared with prospective studies, this was a single-center retrospective study with unavoidable bias. Second, we studied only a Chinese population, limiting our finding's generalizability. Third, we did not consider the effect of T790M mutation on prognosis. Fourth, we did not perform NGS to exclude the effects of coexisting tumor suppressor genes (including TP53, RB1, PTEN and ARID1A) on the PFS and OS of third-generation TKIs for EGFR-positive advanced NSCLC. Therefore, multicenter prospective clinical studies are required to explore the relationship between PD-L1 expression and the prognosis of patients treated with third-generation TKIs.
5. Conclusion
In conclusion, this retrospective study showed that strong PD-L1 expression predicts poor response to EGFR-TKIs therapy in patients with EGFR-mutated NSCLC. Thus, PD-L1 expression can be used as a reliable biomarker for EGFR-TKIs therapy to predict patient survival.
Supplementary Material
Acknowledgments
The authors thank all the patients and their families.
Funding Statement
This study was supported by the National Natural Science Foundation of China (82103632), the Natural Science Foundation of Shandong Province (ZR2021QH245, ZR2022LZL008), and the Facilitating New Life Public Welfare Project (GX2DH04).
Supplemental material
Supplemental data for this article can be accessed at https://doi.org/10.1080/14796694.2024.2385290
Author contributions
Concept and design: J Niu, H Zhua and Y Sun; data management: J Niu, X Jing and Q Xua; formal analysis: J Niu, H Liua and Y Tiana; Survey: J Niu, X Jing and Q Xua; method: Z Yanga, H Zhua and Y Sun; project management: Z Yanga, H Zhua and Y Sun; resources: Z Yanga, H Zhua and Y Sun; supervisors: Z Yanga, H Zhua and Y Sun; Supervision: Z Yanga, H Zhua and Y Sun. J Niu and X Jing wrote the main manuscript text. All authors have read and approved the final version of the manuscript.
Financial disclosure
This study was supported by the National Natural Science Foundation of China (82103632), the Natural Science Foundation of Shandong Province (ZR2021QH245, ZR2022LZL008), and the Facilitating New Life Public Welfare Project (GX2DH04). 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.
Competing interests disclosure
The authors have no competing interests or relevant affiliations with any organization or entity with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
Ethical conduct of research
This study was approved by the Ethical Review Committee of the Affiliated Cancer Hospital of Shandong First Medical University and was conducted in accordance with the Declaration of Helsinki (Ethical approval number: SDTHEC2024001026). Informed consent was obtained from all patients or their legal guardians.
Data availability statement
All the data generated or analyzed during this study are included in this published article. The datasets used and/or analyzed during the current study are available from the corresponding author.
References
Papers of special note have been highlighted as: • of interest; •• of considerable interest
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
All the data generated or analyzed during this study are included in this published article. The datasets used and/or analyzed during the current study are available from the corresponding author.