Pathologic complete response (pCR) with weekly nanoparticle albumin bound (nab-P) plus carboplatin (C) followed by doxorubicin plus cyclophosphamide (AC) with concurrent bevacizumab (B) for triple-negative breast cancer (TNBC).

Abstract

1068 Background: TNBC are mostly “basal-like” tumors, that have been shown to overexpress Secreted Protein Acidic and Rich in Cysteine (SPARC). Endothelial transcytosis of nab-P via albumin- gp60 -cav1 and binding of albumin to SPARC results in high intratumoral levels of nab-P. Exploiting this and the dysfunctional DNA repair in basal tumors, we hypothesized that nab-P + C would produce high rates of pCR in TNBC, further enhanced by antiangiogenesis properties of B. Methods: Eligible women had operable TNBC ≥ 2 cm. pCR in the breast and pCR in the breast + nodes were primary & secondary end points respectively. We needed 57 evaluable patients to demonstrate 40% pCR vs. 25% (P0) in a single stage phase II design (α: 0.05, β: 0.2).Schema: C AUC 6 d1 + nab-P 100mg/m2d 1, 8 & 15 Q 28 d x 4 cycles followed by AC d1, Q14d x 4 cycles preoperatively with B 10mg/kg Q 14d for the first 6 cycles of preoperative chemotherapy, resuming postoperatively to complete 1 year of treatment.Baseline tumor biopsies & serial serum/blood samples were collected. Results: Due to slow accrual, study was closed after 42 patients. They were women between 35 and 68 years of age (median 52); 51% were African American and 46% were node positive. Safety population: N=41. Four patients came off study prior to surgery while 7 are still on pre-op treatment. Grade ¾ hematologic AEs: neutropenia (Gr3: 56%; Gr4:24%) febrile neutropenia (4%), thrombocytopenia (32%), anemia (22%). 7 patients had SAEs, with 1 grade 5 event. To date, thirty of 31 patients who had surgery (efficacy population) are considered evaluable per protocol. In-breast pCR rates are 55% (17/31) and 56% (17/30) and the rates of pCR breast + nodes are 52% (16/31) and 53% (16/30), for the efficacy and evaluable populations respectively. Conclusions: Majority of the patients in our study achieved a pCR, which is among the highest rates reported compared to anthracyclines+ taxanes without B in TNBC. Correlative analyses are planned. An ongoing randomized intergroup study is evaluating the individual contributions of carboplatin & bevacizumab to pCR in TNBC. Clinical trial information: NCT00777673.