Radiation therapy (RT)-free pembrolizumab plus chemotherapy (P+C) for PD-L1 TPS ≥50% locally advanced non-small cell lung cancer (LA-NSCLC): Primary analysis from multicenter single arm phase II study (Evolution trial; WJOG11819L).

LBA8050 Background: Standard of care for unresectable LA-NSCLC is chemoradiation therapy (CRT) followed by durvalumab (D). Survival curves of P monotherapy/P+C for PD-L1 TPS ≥50% stage IV NSCLC suggested possible comparable survival to CRT for stage III patients (pts). Moreover, some studies of neoadjuvant C+immunotherapy (I) for stage III pts have demonstrated high pathological complete response and major pathological response rates, implying potentially outstanding efficacy of C+I for earlier stage. We thus hypothesized P+C without RT in PD-L1 ≥50% LA-NSCLC pts provides a comparable efficacy to CRT followed by D while avoiding CRT-induced severe toxicities. Methods: This is a phase II study conducted by West Japan Oncology Group. P with platinum plus pemetrexed (PEM) (non-squamous) or P with carboplatin plus nab-paclitaxel (squamous) was administered every 3 weeks without RT. After four cycles of induction P+C, P with PEM (non-squamous) or P alone (squamous) was continued until progression or 2 years. The primary endpoint was 2 year-PFS rate (threshold/expected: 20%/45%). Results: Between May 2020 and February 2022, 21 pts were enrolled. Median age was 73 (range, 53-89). Stage IIIA/B/C included 11 (52%)/7 (33%)/3 (14%), respectively. Histologic subtypes were 14 (67%) adenocarcinoma, 5 (24%) squamous cell carcinoma, and 2 (10%) others. Median follow-up period was 29.9 (range, 0.3-44.2) months. Median number of P administrations was 30 (range, 1-35). The primary endpoint was met with 2-year PFS rate of 67% (90% CI: 46-83%). At the time of data cut-off, 13 (62%) of 21 pts were still progression-free. Median PFS and OS were not reached. Two-year OS rate was 85%. Centrally reviewed tumor response: 8 (38%) CR; 9 (43%) PR; 3 (14%) SD; and 1 (5%) NE were confirmed, resulting in overall response rate (ORR) of 81% and disease control rate of 95%. ORRs/2-year PFS rates of PD-L1 TPS 50-79% and 80-100% were 67%/56% and 92%/75%, respectively. Non-hematological AEs ≥grade 3 were observed in 11 (52%) pts, including: 2 (10%) pneumonitis; 2 (10%) pneumonia; 1 (5%) diarrhea; 1 (5%) ALT elevation; and 1 (5%) acute heart failure. There was one (5%) grade 5 AE (pneumonia). Conclusions: RT-free P+C provided long-lasting responses in approximately two-thirds of pts. Higher PD-L1 TPS cases achieved higher RR, including some CRs and higher 2-year PFS rate. To confirm our hypothesis that RT-free P+C can be a less toxic curative option in selected LA-NSCLC pts with PD-L1 TPS ≥50%, further data is warranted. Clinical trial information: NCT04153734 .