Oncolytic T-VEC virotherapy plus neoadjuvant chemotherapy in nonmetastatic triple-negative breast cancer: a phase 2 trial.

Talimogene laherparepvec (T-VEC) is an oncolytic virus hypothesized to enhance triple-negative breast cancer (TNBC) responses to neoadjuvant chemotherapy (NAC). This article describes the phase 2 trial of T-VEC plus NAC (ClinicalTrials.gov ID: NCT02779855 ). Patients with stage 2-3 TNBC received five intratumoral T-VEC injections with paclitaxel followed by doxorubicin and cyclophosphamide and surgery to assess residual cancer burden index (RCB). The primary end point was RCB0 rate. Secondary end points were RCB0-1 rate, recurrence rate, toxicity and immune correlates. Thirty-seven patients were evaluated. Common T-VEC toxicities were fevers, chills, headache, fatigue and injection site pain. NAC toxicities were as expected. Four thromboembolic events occurred. The primary end point was met with an estimated RCB0 rate = 45.9% and RCB0-1 descriptive rate = 65%. The 2-year disease-free rate is equal to 89% with no recurrences in RCB0-1 patients. Immune activation during treatment correlated with response. T-VEC plus NAC in TNBC may increase RCB0-1 rates. These results support continued investigation of T-VEC plus NAC for TNBC.