A phase Ib study of camrelizumab in combination with apatinib and fuzuloparib in patients with recurrent or metastatic triple-negative breast cancer

Background Strategies to improve activity of immune checkpoint inhibitors for triple-negative breast cancer (TNBC) are needed. Preclinical studies showed that antiangiogenic agents and poly (ADP-ribose) polymerase (PARP) inhibitors might sensitize tumors to immunotherapy. Here, we investigated the tolerability, safety, and preliminary antitumor activity of camrelizumab, an anti-PD-1 antibody, in combination with apatinib, a vascular endothelial growth factor receptor-2 inhibitor, and fuzuloparib, a PARP inhibitor, in patients with recurrent or metastatic TNBC. Methods This phase Ib study included a dose-finding part and a dose-expansion part. In the dose-finding part, a 3 + 3 dose escalation scheme was introduced. Patients were given camrelizumab (200 mg every 2 weeks) plus apatinib (375 mg or 500 mg once daily) and fuzuloparib (starting dose 100 mg twice daily) every 28-day cycle. After evaluation of the tolerability and safety of the dosing regimens, a clinical recommended dose was determined for the dose-expansion part. The primary endpoint was dose-limiting toxicity (DLT). Results A total of 32 patients were enrolled. Three patients received camrelizumab 200 mg + apatinib 375 mg + fuzuloparib 100 mg, and 29 received camrelizumab 200 mg + apatinib 500 mg + fuzuloparib 100 mg (clinical recommended dose). No DLTs were observed in either group. The most common grade >= 3 treatment-related adverse events were decreased white blood cell count (20.7%), hypertension (13.8%), decreased neutrophil count (10.3%), and increased aspartate aminotransferase (10.3%). Two patients discontinued study treatment due to immune-mediated hepatitis (n = 1) and anemia, decreased platelet count, decreased white blood cell count, increased alanine aminotransferase, increased aspartate aminotransferase, and increased gamma-glutamyltransferase (n = 1). One patient died of unknown cause. Two (6.9% [95% CI, 0.9-22.8]) of 29 patients with camrelizumab 200 mg + apatinib 500 mg + fuzuloparib 100 mg had objective response. The disease control rate was 62.1% (95% CI, 42.3-79.3). The median progression-free survival was 5.2 months (95% CI, 3.6-7.3), and the 12-month overall survival rate was 64.2% (95% CI, 19.0-88.8). Conclusions Combination of camrelizumab plus apatinib and fuzuloparib showed manageable safety profile and preliminary antitumor activity in patients with recurrent or metastatic TNBC.