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MINI 03 - PD1 Axis Inhibition and EGFR (ID 101)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
MINI03.01 - Prior TKI Therapy in NSCLC EGFR Mutant Patients Associates with Lack of Response to Anti-PD-1 Treatment (ID 2172)
16:45 - 18:15 | Author(s): K.Y. Kim
Programmed cell death-1 (PD-1) inhibitors have shown significant potential to induce durable responses in non-small cell lung cancer (NSCLC). Although responses have been seen in patients (pts) whose tumors harbor epidermal growth factor receptor (EGFR) mutations (EGFRm), data to date with inhibitors of PD-1, or its ligand PD-L1, suggest that responses are less frequent in EGFRm NSCLC. Studies in which EGFRm pts receive EGFR tyrosine kinase inhibitors (TKIs) and PD-1 inhibitors in sequence or concurrently are being conducted. However, based on the high response rate with EGFR TKIs in EGFRm pts, PD-1 inhibition does not precede the EGFR TKIs in these study designs.
We evaluated data from our experience at UCLA as part of the KEYNOTE-001 clinical trial, in which pts received pembrolizumab 2 mg/kg every 3 weeks or 10 mg/kg every 2 or 3 weeks. Early in the trial, an amendment excluded EGFRm, EGFR TKI naïve pts, however a subsequent amendment allowed such pts if their mutation was non-sensitizing to approved EGFR TKIs. Although the trial employed central radiographic assessment by RECIST v1.1 (available to the sponsor but not the sites), clinical decisions and the assessment we describe were based on investigator-assessed immune-related response criteria. Groups were compared using Fisher’s exact test. Western blot was performed using standard techniques, exposing human non-small cell lung cancer cell lines HCC-827, H1975, Calu3 and H460 to erlotinib or afatinib at 1µM or control using the antibody PD-L1 mAb #1368 (Cell Signaling) and α-tubulin antibody #2144 (Cell Signaling).
We enrolled 29 EGFRm pts. 2 of 3 EGFR TKI naïve pts experienced a partial response (PR) compared to 1 of 26 enrolled after a prior EGFR TKI (p<0.001). 18 of these 29 pts had a 9 week scan. Of these, PR was seen in both EGFR TKI naïve pts (one L858R mutation and one exon 20 insertion) compared to 1 of 16 enrolled after a prior EGFR TKI (p<0.001). Of note, a similar trend of increased responses in EGFR TKI naïve pts was not seen in EGFR wild type pts. In vitro experiments using erlotinib and afatinib showed unchanged PD-L1 levels in cell lines not inhibited by the EGFR TKI used, but reduced PD-L1 in EGFRm cell lines inhibited by the TKI. Of note, the only responder among the EGFR TKI-treated EGFRm pts was one of only 4 of the 16 scanned post-TKI pts who had a non-sensitizing mutation. So, 0 of 22 EGFRm pts with a sensitizing mutation responded after an EGFR TKI.
A retrospective analysis in EGFRm NSCLC showed a strong correlation between response and lack of prior EGFR TKI treatment. PD-L1 levels decrease in response to an EGFR TKI in cell lines sensitive to the TKI. Immunohistochemistry evaluating the presence and location of relevant proteins and immune effector cells are ongoing as is whole exome sequencing. These results have implications for the design of clinical trials of PD-1 inhibitors in EGFRm pts. Supported by: 1K23CA149079, One Ball Matt Memorial Golf Tournament, Kasdan Family
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