A Phase Ii Study Of Bemcentinib (Bgb324), A First-In-Class Highly Selective Axl Inhibitor, With Pembrolizumab In Pts With Advanced Nsclc: Os For Stage I And Preliminary Stage Ii Efficacy.

9098 Background: AXL is an RTK implicated in epithelial-to-mesenchymal transition and as a resistance mechanism to multiple therapies including anti-PD1. Bemcentinib (BGB324) is a first-in-class, oral, highly selective and potent AXL inhibitor which has been demonstrated to enhance anti-PD1 therapy in the pre-clinical setting. Methods: This is a Phase II single-arm, two-Stage study with bemcentinib (200mg/d) and pembrolizumab (200 mg/q3wk) for previously treated, IO naïve pts (n = 48 in total) with Stage IV lung adenocarcinoma. The primary endpoint was ORR according to RECIST 1.1 with pre-defined minimum requirement for 18% RR in the first Stage (n = 24) to proceed to Stage 2. Secondary endpoints included DCR, PFS, OS and safety. Tumour biopsies were analysed for PD-L1 (22C3 pharmDx), AXL, and infiltrating immune cells. Results: Stage 1 completed enrolment in Apr ‘18. As of Feb ‘19, 38 pts (24 and 14 in Stage 1 and 2, respectively) have been dosed with the combination; median age 66 (range 39-79) yr, 59% male, all previously received one prior line of platinum-based chemotherapy or a licensed EGFR/ALK-directed therapy. The most common TRAEs (occurring in > 15% of pts) were transaminase increases (37%), diarrhoea (29%), and asthenia (17%). All cases of transaminase increase were reversible and resolved with concomitant administration of systemic corticosteroids and interruption of study treatments. At time of writing, Stage 1 had met the efficacy threshold to proceed to Stage 2 with continued enrolment. Among 29 pts evaluable for response 7 PRs were reported (24%). For AXL positive pts (10/21 with available biopsies), ORR was 40%. PD-L1 status was known for 5 responders: 4 pts (80%) were PD-L1 negative or weakly positive. In Stage 1, mPFS was 4.0 months (95% CI 1.9 – NR) and 5.9 months in AXL positive pts (n = 10; 3.0 - NR). mOS was not mature. Conclusions: Overall, bemcentinib in combination with pembrolizumab was well tolerated and promising clinical activity was seen, particularly in pts with AXL positive disease. Updated results will be reported at the meeting, incl 12-month OS for Stage 1 and preliminary efficacy of Stage 2. Clinical trial information: NCT03184571.