SHR-1701 plus chemotherapy as first-line treatment for unresectable locally advanced, recurrent or metastatic esophageal squamous cell carcinoma (ESCC).

Abstract

363 Background: Platinum-based chemotherapy is the standard first-line treatment for advanced or metastatic ESCC. Recently, the combination of PD-(L)1 pathway blockade with chemotherapy has shown synergistic efficacy in a few clinical trials. SHR-1701 is a novel bifunctional fusion protein composed of a mAb against PD-L1 fused with the extracellular domain of TGF-β receptor II. The purpose of this ongoing phase II trial (ChiCTR2000039909) was to evaluate the efficacy and safety of SHR-1701 combined with chemotherapy for unresectable locally advanced, recurrent or metastatic ESCC in China. Methods: This trial enrolled systemic treatment-naive patients(pts) with histologically or cytologically confirmed unresectable locally advanced, recurrent or metastatic ESCC who had ECOG PS of 0-1. Eligible pts received SHR-1701 (30mg/kg, iv, d1, q3w) combined with up to 6 cycles of albumin-bound paclitaxel (125mg/m2, iv, d1, d8, q3w) and cisplatin (75mg/m2, iv, d1, q3w). For those without progressive disease, maintenance treatment was administrated with SHR-1701 monotherapy until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression free survival (PFS), overall survival (OS), disease control rate (DCR), safety and biomarkers. Results: As of September 21, 2022, 18 pts were enrolled. The median age was 67.5 years (range: 46–75 years) and 16 (88.9%) were male. 10 of the pts (55.6%) presented with distant metastasis. 14 pts were included in the efficacy analysis and 17 were in the safety analysis. The ORR and DCR were 85.7% and 100.0%, respectively. One patient achieved a complete response (CR) which will reach confirmation at next visit. 11 pts had partial response (PR), including 9 confirmed PR, one pending confirmation PR, and one unconfirmed PR. In addition, one PR patient got a CR target lesion. Grade 3-4 treatment-related adverse events (AEs) were observed in 23.5% of pts, including neutropenia (11.8%), leukopenia (5.9%), anemia (5.9%), emesis (5.9%) and rash (5.9%). Immune-related AEs (irAEs) were observed in 52.9%, and only one grade 3 irAE of rash occurred. Conclusions: SHR-1701 plus chemotherapy showed potential clinical benefits with acceptable toxicity as first-line treatment, and it might be a favorable option for pts with advanced ESCC. Clinical trial information: ChiCTR2000039909 .