Safety and efficacy of Pucotenlimab (HX008) - a humanized immunoglobulin G4 monoclonal antibody in patients with locally advanced or metastatic melanoma: a single-arm, multicenter, phase II study

BACKGROUND: Pucotenlimab is a novel recombinant humanized anti-PD-1 (Programmed death-1) monoclonal antibody, which belongs to the human IgG4/kappa subtype, and can selectively block the binding of PD-1 with its ligands PD-L1 and PD-L2. METHODS: In this phase 2 trial, patients with locally advanced or metastatic melanoma who had failed conventional treatment (chemotherapy, targeted therapy, interferon, IL-2, et al.) were recruited. The patients were administrated with Pucotenlimab of 3 mg/kg every 3 weeks until disease progression, intolerable toxicity, or treatment discontinuation for any other reasons. The primary endpoint was the overall response rate (ORR). The secondary endpoints were disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), overall survival (OS), and toxicity. RESULTS: One-hundred and nineteen patients were enrolled and followed up for 19.32 (ranging from 15.901 to 24.608) months by the cutoff date of July 30(th), 2021. The ORR was 20.17% (24/119, 95% CI, 13.370%-28.506%) based on both independent review committee (IRC) and the investigator’s assessment per RECIST v1.1. The median PFS were 2.89 (95% CI, 2.037–4.074) months and 2.46 (95% CI, 2.004–4.008) months based on IRC and investigator’s assessment, respectively, per RECIST v1.1. The median OS was 16.59 (95% CI, 13.963–26.973) months. Treatment-related adverse events (TRAEs) occurred in 77.3% (92/119) of the patients. The incidence of Grade ≥ 3 TRAEs was 15.1% (18/119). In addition, none of the patients died because of TRAEs. As for biomarker analysis, Eotaxin (CCL11) and MCP-1 (CCL2) were related to treatment response, while TNF-α and VEGF were related to treatment failure. CONCLUSIONS: Pucotenlimab as a ≥ 2(nd) line therapy showed promising efficacy and tolerable toxicity for patients with locally advanced or metastatic melanoma. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT04749485 (registered retrospectively on 11/02/2021).