Erica Mayer, MD, of Dana-Farber Cancer Institute shared results from TBCRC 56, showing presurgical treatment with a PARP inhibitor + anti-PD1 combo in patients with gBRCAm early triple-negative breast cancer resulted in a pCR rate of 50%. Further ongoing correlative work may identify the best candidates for this non-chemo approach.
I'm Erica Mayer from Dana-Farber Cancer Institute in Boston, and I'm excited to present results from the triple negative cohorts of TBCRC 056, which is a phase 2 study of preoperative PARP inhibitor, naraparib, and a PD1 inhibitor, desarliab, for patients who have BRCA mutated breast cancer. TPCRC-056 was designed to evaluate the combination of PARP inhibitor and PD1 in the preoperative setting for patients with germline BRCA12 mutations. So, this study was a, um, prospective investigator-initiated multi-center study that has been run across the United States throughout the Translational Breast Cancer Research Consortium. There are 3 arms of the study. Um, 2 arms, which are randomized, are for patients with triple negative breast cancer, and that's what we're presenting at San Antonio. There's a 3rd arm, uh, that's, uh, smaller and exploratory for patients with ER positive disease. We actually presented results from this arm last year at San Antonio. Eligible patients for, um, the triple negative arms had, uh, stage 1 to 3 breast cancer, triple negative disease, and a germline BRCA mutation. Patients were randomized to receive either the combination of the PARP inhibitor nerarib, and the PD1 inhibitor dearliab together for 18 weeks, or start with a lead-in of just the PARP inhibitor nerarib, and then adding the PD1 inhibitor to Starliab at cycle 2 and onwards. After 18 weeks or 6 cycles, patients then either went to surgery, or if there was not enough, uh, cyto reduction, they could cross over to receive additional. Preoperative systemic therapy. Overall, we enrolled 46 patients in the triple negative cohorts. And in general, this was a population that reflects what we see in, in germline mutated disease. Uh, average age, our median age was about 40. Um, about half the patients had stage 2 disease, about 24% had node positive disease, and the majority of patients, 82% had a BRCA1 mutation. A minority had a BRCA2 mutation. What we saw in our results for the primary, one of the primary endpoints was that, um, patients who received this treatment had a pathologic complete response rate of 50% after 18 weeks of treatment with this, um, non-chemotherapy, all targeted approach regimen. And this result, 50% was same in arm A and A B, and it was the same whether patients had BRCA1 or BRCA2 mutation. We also looked at, um, the combination of, uh, residual cancer burden scores, uh, 0 and 1, which is PATCR and near PATCR, and our rate was 60%. So, this is a, a really robust rate for only 18 weeks of treatment, and really exciting to see this with a non-chemotherapy regimen.
