A phase II trial combining SHR-1316, bevacizumab, and cisplatin/carboplatin in patients with TNBC with active brain metastases.

e13133 Background: Triple-negative breast cancer (TNBC) has a high risk of brain metastases (BM), leading to poor survival. Treatment options for BMs are limited, and the combination of chemotherapy and immune checkpoint inhibitor is the standard-of-care for PD-L1 positive metastatic TNBC. Platinum-based systematic therapy is the mainstay of TNBC treatment and the addition of bevacizumab has shown improvement in the progression-free survival (PFS) of patients with BM. Therefore, this study aims to investigate the efficacy and safety of SHR-1316 (anti-PD-L1) in combination with bevacizumab and cisplatin/carboplatin in TNBC patients with BMs. Methods: In this single-center phase II trial, TNBC patients with active BM received SHR-1316, bevacizumab, and cisplatin/carboplatin. Prior treatment with bevacizumab or anti-PD-1/PD-L1 were not allowed. Prior platinum was allowed only in cases of previous platinum-sensitive response. The primary endpoint was objective response rate (ORR) of central nervous system (CNS), as assessed according to the response assessment in neuro-oncology brain metastases. The secondary endpoint included clinical benefit rate (CBR) of CNS, PFS, overall survival (OS), first progression site and safety. Results: As of January 12 th , 2024, a total of 23 female patients with ECOG PS≥1(100%) were enrolled. The median number of previous lines of therapy for metastatic disease was 1 (0-3). All patients had active BM, of which 87% (20/23) were BM treatment-naïve and 13% (3/23) had BM progression after previous local therapy, 26.1% (6/23) had received a prior platinum agent. Of the 23 evaluable patients, the confirmed CNS ORR was 65.2% (95%CI: 42.7%-83.6%), with 3 complete response (CR), 12 partial response (PR), 7 stable disease (SD), and 1 progressive disease (PD). The median CNS-PFS was 11.2 months (95%CI, 5.8 to not reached), median PFS was 7.6 months (95%CI, 5.7-11.9), and median OS was 13.2 months (95%CI, 9.5 to not reached). Treatment-related adverse events (TRAEs) were reported in all 23 patients, and the most common TRAEs were neutrophil count decreased (69.6%, 16/23), anemia (65.2%, 15/23), asthenia (60.9%, 14/23), Hypomagnesaemia (56.5%, 13/23), leukopenia (52.2%, 12/23) and electrocardiogram T wave abnormal (52.2%, 12/23). The incidence of grade ≥3 TRAEs was 43.5% (10/23), including neutropenia (13%, 3/23), platelet count decreased (8.7%, 2/23), and hypertension (8.7%, 2/23). Only one patient had a grade 4 TRAE (lymphocytopenia), and SHR-1316 related serious adverse event (facial nerve disorder) occurred in only one patient. No grade 5 AEs were noted. Conclusions: SHR-1316 plus bevacizumab and cisplatin/carboplatin achieves a significant improvement in CNS ORR and brings PFS and OS benefits in TNBC patients with active BMs. As an effective and safe treatment, this triple-combination warrants further investigation. Clinical trial information: NCT04303988 .