Voorwerk and Slagter et al. report on a phase 2 clinical trial of 66 triple-negative breast cancer patients treated with nivolumab preceded by low-dose irradiation or chemotherapy. In this ‘pick-the-winner’ trial design, pretreatment with doxorubicin or cisplatin upregulated inflammatory and immune-related gene profiles in tumors and increased objective response rates compared to cyclophosphamide or irradiation. Responders showed higher PD-L1 on immune cells, reduced circulating carcinoembryonic antigen levels, and increased TCR infiltration, clonality and diversity on treatment (particularly in the doxorubicin arm); mutational burden did not correlate with response.
Contributed by Alex Najibi
The efficacy of programmed cell death protein 1 (PD-1) blockade in metastatic triple-negative breast cancer (TNBC) is low(1-5), highlighting a need for strategies that render the tumor microenvironment more sensitive to PD-1 blockade. Preclinical research has suggested immunomodulatory properties for chemotherapy and irradiation(6-13). In the first stage of this adaptive, non-comparative phase 2 trial, 67 patients with metastatic TNBC were randomized to nivolumab (1) without induction or with 2-week low-dose induction, or with (2) irradiation (3 x 8 Gy), (3) cyclophosphamide, (4) cisplatin or (5) doxorubicin, all followed by nivolumab. In the overall cohort, the objective response rate (ORR; iRECIST(14)) was 20%. The majority of responses were observed in the cisplatin (ORR 23%) and doxorubicin (ORR 35%) cohorts. After doxorubicin and cisplatin induction, we detected an upregulation of immune-related genes involved in PD-1-PD-L1 (programmed death ligand 1) and T cell cytotoxicity pathways. This was further supported by enrichment among upregulated genes related to inflammation, JAK-STAT and TNF-alpha signaling after doxorubicin. Together, the clinical and translational data of this study indicate that short-term doxorubicin and cisplatin may induce a more favorable tumor microenvironment and increase the likelihood of response to PD-1 blockade in TNBC. These data warrant confirmation in TNBC and exploration of induction treatments prior to PD-1 blockade in other cancer types.