Abstract CT202: Xevinapant plus avelumab in patients (pts) with advanced or metastatic non-small cell lung cancer (NSCLC): Phase 1b dose-expansion results and exploratory biomarker analyses

• Published in: Cancer research (Chicago, Ill.) Ill.), 2023-04, Vol.83 (8_Supplement), p.CT202-CT202
• Main Authors: Chu, Quincy, Ciuleanu, Tudor, Ramlau, Rodryg, Renouf, Daniel, Juergens, Rosalyn, Kalinka, Ewa, Sawrycki, Piotr, Bramson, Jonathan, Nelson, Brad, Crabbé, Rafael, Sahlender, Daniela A., Crompton, Philippa, Rouits, Elisabeth, Spaggiari, Dany, Brichory, Franck, Piggott, Luke, Schenker, Mike, Goss, Glenwood
• Format: Article
• Language: English
• ISSN: 1538-7445; 1538-7445
• DOI: 10.1158/1538-7445.AM2023-CT202

BACKGROUND: Combining anti-PD-1/L1 antibodies and agents that restore cancer cell susceptibility to apoptosis may enhance antitumor activity. We report results from a phase 1b dose-expansion cohort of xevinapant, a first-in-class, oral, small-molecule IAP (inhibitor of apoptosis protein) inhibitor that restores cancer cell sensitivity to apoptosis, and avelumab (anti-PD-L1) in pts with advanced NSCLC. METHODS: The recommended phase 2 dose (RP2D; 28-day cycles of xevinapant 200 mg/day [days 1-10 and 15-24] + avelumab 10 mg/kg [days 1 and 15]) was previously established during the dose-escalation part of this phase 1, open-label study. In this dose-expansion cohort, pts with advanced NSCLC who progressed on first-line (1L) platinum-based chemotherapy (CTx) or anti-PD-1/L1 ± platinum-based CTx received xevinapant (at RP2D) + avelumab for 13 cycles. The primary endpoint was objective response rate (ORR) per RECIST 1.1. Secondary endpoints included duration of response (DoR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), safety, and pharmacokinetics (PK). RESULTS: 38 pts were treated: most had squamous cell carcinoma (45%) or adenocarcinoma (42%) of the lung, 11% had prior anti-PD-L1 therapy, 71% were men, and median age was 62 years (range, 35-75). 1 pt completed 13 cycles, and 37 permanently discontinued treatment; most common reasons were progressive disease (PD; 70%) and adverse events (AEs; 27%). ORR was 10.5% (95% CI 2.9-24.8). Best overall response (BOR): 4 pts had a confirmed partial response (PR), 19 had stable disease, and 15 had PD. Median DoR in responders was 15.9 months (95% CI 3.5-29.7); DCR was 60.5% (95% CI 43.4-76.0). Median PFS was 3.5 months (95% CI 1.9-5.1); median OS was 9.4 months (95% CI 6.7-16.2). Most pts (n=37; 97.4%) had treatment-emergent AEs (TEAEs); 21 (55.3%) had grade ≥3. Most common TEAEs were decreased appetite (n=13; 34.2%) and ALT increase (n=11; 28.9%). Nine pts died due to TEAEs; none were considered treatment-related. Xevinapant and avelumab PK were comparable to monotherapy at the same doses. In exploratory biomarker analyses, plasma IL-10 levels increased during the study treatment period. In blood, activated CD4 T cells and Tregs increased during cycle 1, and activated CD8 T cells increased during the treatment period; however, these did not correlate with antitumor activity. In tumor samples, low Ki67 expression was associated with BOR of PR (n=4), and increases in macrophages, Tr