1019P Pattern of clinical activity of anticancer vaccine OSE2101 in HLA-A2+ non-small cell lung cancer (NSCLC) patients after failure to immune checkpoint inhibitors (IO) in phase III Atalante-1 randomized trial

Abstract

OSE2101 (Tedopi) is an anticancer vaccine increasing overall survival (OS) with HR of 0.59 (p=0.017) versus Standard of Care Chemotherapy (SoC CT) in the population of interest (PoI) of HLA-A2+ NSCLC patients with IO secondary resistance after sequential CT-IO (ESMO 2021 #47LBA). The objective of this analysis was to explore the pattern of activity of OSE2101. 118 NSCLC EGFR and ALK negative patients were randomized (2:1) in OSE2101 or SoC (docetaxel or pemetrexed) in the PoI. OS of OSE2101 versus SoC was described according to best response (partial response (PR), Stable Disease (SD) and Progressive Disease (PD)) and to the administration of post progression anticancer treatment. OS was described in Late Progressors (LP) defined as no RECIST 1.1 nor clinical PD within the first 6 months after randomization. Median (95%CI) OS in months by best response and by post progression anticancer treatment are described in the table. 16 (20%) patients fulfilled the criteria for Late Progressors with OSE2101. Late Progressors included 4 (25%) patients with PR and 12 (75%) patients with prolonged SD. mOS was 14.7 months with 1-year OS rate of 68%. mPFS was 8.8 months with 23% of patients progression-free at 1-year.Table: 1019PmOS (months)OSE2101 n=80SoC n=38By Best ResponsePRn=6 11.2 (5.4, NE)n=7 13.8 (2.6, NE)HR=0.75 (0.18, 3.23)SDn=36 13.1 (8.8, 16.8)n=19 9.4 (6.5, 12.2)HR=0.61 (0.33, 1.14)PDn=32 8.0 (5.4, 11.1)n=7 5.0 (1.0, 7.2)HR=0.45 (0.19, 1.04)By Post Progression anticancer treatmentWith anticancer treatmentn=55 13.5 (9.6,16.6)n=16 10.6 (7.2, 16.1)HR=0.71 (0.38, 1.30)Without anticancer treatmentn=25 6.3 (3.6, 7.6)n=22 4.5 (2.3, 8.3)HR=0.76 (0.41, 1.41) Open table in a new tab In advanced HLA-A2+ NSCLC patients with IO secondary resistance after sequential CT-IO, OS was longer with OSE2101 versus SoC regardless the use of post progression anticancer treatment. By Best Response to study treatement, OS was longer with OSE2101 in patients with Stable Disease or Progressive Disease compared to SoC. Late progressors with OSE2101 were mainly driven by long Stable Disease. These data suggest that the cancer vaccine OSE2101 may act as an anti-tumor brake in controlling the tumor growth regardless of best response.