1468P Patients’ Perspective on Tolerability of Dostarlimab in NSCLC: Patient-reported Outcomes from the Phase II PERLA Trial

In the phase II double-blind PERLA trial (NCT04581824), dostarlimab + chemotherapy (DCT) showed similar efficacy to pembrolizumab + CT (PCT) as first-line treatment (tx) for patients (pts) with metastatic non-oncogene-driven, non-squamous, non-small cell lung cancer (NSCLC); the proportion of pts experiencing tx-related adverse events (TRAEs) or AEs leading to tx discontinuation was similar between groups [1]. Exploratory analyses of pt-reported measures of tolerability were conducted. Eligible pts with ECOG 0–1 were randomized 1:1 to receive ≤35 cycles (C) of DCT or PCT every 3 weeks (Q3W) (CT: ≤35 C of 500 mg/m2 pemetrexed + ≤4 C of cisplatin or carboplatin). Patient-reported outcome version of CTCAE (PRO-CTCAE) and the tolerability item of FACT-G (FACT-GP5) were collected at Day 1 C1, then Q3W to Week 12, Q9W to Week 48, Q12W to end of tx, at end of tx, and 30-day safety follow-up. Completion rates for PRO-CTCAE (DCT N=96/PCT N=88) and FACT-GP5 (DCT N=95/PCT N=87) were >80% up to C4, then decreased in both tx arms. At baseline (BL), only the urinate frequently item had >10% of pts reporting occurrence as “frequently” or greater per PRO-CTCAE (DCT: 11.5% [n=11/96]; PCT: 10.2% [n=9/88]); “severe” or greater severity and “quite a bit” or greater interference responses were reported in <10% of pts. At C13 (∼1 yr of tx) urinate frequently was similar between arms (“frequently” or greater in DCT: 12.5% [n=4/32]; PCT: 10% [n=2/20]). Relative to BL, at C13 muscle and joint ache frequency, severity and interference responses of “quite a bit” or greater were increased in both arms, but occurred in <16% of pts. Per FACT-GP5, at BL (i.e., before trial tx) 85.3/94.3% of DCT/PCT pts were “not at all” or “a little bit” bothered by tx side effects; at C13 this was 77.4/84.2% and no pts in either arm were “very much” bothered. Most pts reported little or no bother from tx side effects and responses were similar across tx arms, suggesting interventions are tolerable from pt perspective. These results supplement previously reported PERLA data and support further investigation of dostarlimab combined with existing and novel therapies in metastatic NSCLC. 1. Peters S, et al. 2022; Oral; ESMO-IO (7–9 Dec, Geneva). Funding: GSK (213403).