342P - Prognostic implications of PD-L1 co-expression among Filipino EGFR MT mNSCLC

Background

TKIs targeting EGFR MT are standard for mNSCLC. Reports suggest co-expression of PD-L1 may play a role in acquiring TKIS resistance. This PDL1 prognostic role remains largely debatable. This study reports the influence of PD-L1 among EGFR MT mNSCLC Filipino cohort.

Methods

30 mNSCLC with EGFR mutation, PDL1, & TPS analyses were enrolled. Radiologic response was documented using RECIST 1.1. mPFS & mOS were estimated using Kaplan-Meier. Bivariate analyzed using Pearson’s correlation (P).

Results

Among 30 enrolled, 57% had exon19 del & 43% had exon21 L858R. 40% were PDL1-ve & 60% were PDL1+ve. Among PDL1+ve, 56% had low TPS & 44% had high TPS. 10% had Afatinib, 50% for Gefitinib, 27% for Erlotinib, & 13% for Osimertinib. PDL1-ve EGFR MT mPFS (exon19 ≥ 239d & exon21 = 163d, p= 0.28) were shorter compared to PDL1+ve counterparts, exon19 (PDL1 low = 392d & PDL1 high = 478d, p= 0.77) & exon21 (PDL1 low ≥ 888d & PDL1 high = 208d, p= 0.12). Exon19 & exon21 EGFR MT without PDL1 mOS were ≥ 278d and 369d, p=0.31, respectively. exon19 MT with low & high PDL1 TPS mOS were ≥ 969d & 478d (p= 0.08), respectively. exon21 MT with low & high PDL1 TPS mOS were ≥888d & 345d, p=0.22, respectively. Erlotinib & Gefitinib achieved higher mPFS trend [874d & 311d (p= 0.21), respectively], followed by Osimertinib & Afatinib with mPFS of 175d & 137d (p= 0.808), respectively. Erlotinib & Osimertinib had higher mOS trend (both ≥969d, p=0.5), followed by Gefitinib & Afatinib with mOS of ≥ 888d & 150d (p= 0.034), respectively. Pearson’s correlation showed Gefitinib & Erlotinib had the largest contribution with outcomes in exon19 del (P= 0.42 vs. -0.27 to -0.07 for other TKIs) & exon21 L858R (P= 0.27 vs. -0.42 to 0.07 for other TKIs), respectively. No significant correlations were observed with PDL1 & TKI (same P values).

Conclusions

Exon19 del & exon21 L858R MT with low PD-L1 TPS had the most favorable PFS & OS compared to their mutant high PD-L1 TPS & PD-L1 negative counterparts. In addition, Erlotinib treatment had the most favorable PFS & OS compared to other TKIs. Exon19 deletion & exon21 L858R strongly correlates with Gefitinib & Erlotinib treatments, respectively. However, PD-L1 status had no significant correlation with TKI treatment. Further research are needed to establish consistency in the observed findings.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Department of Science and Technology - Philippine Council for Health Research and Development; Lung Center of the Philippines; National Kidney and Transplant Institute; East Avenue Medical Center.

Funding

Department of Science and Technology - Philippine Council for Health Research and Development.

Disclosure

All authors have declared no conflicts of interest.