A dendritic cell vaccine that targets HER2 protein may induce an immune response leading to regression of early-stage breast tumors, according to results of research from the Moffitt Cancer Center published in Clinical Cancer Research.
Fifty-four HER2-positive patents were enrolled in a neoadjuvant HER2 peptide-pulsed DC1 vaccine trial. Of the enrolled patients, 42 had ductal carcinoma in situ (DCIS) and 12 had early invasive breast cancer (IBC). The patients were randomized to receive intralesional (IL, n = 19), intranodal (IN, n = 19), or both intralesional and intranodal (ILN, n =16) injection. Responses were measured in peripheral blood and sentinel lymph nodes by in vitro sensitization assay or ELISPOT. Resected surgical specimens were assessed to determine pathologic response.
Vaccination by all routes was well tolerated and the rate of immune response did not differ significantly based on vaccination route (IL 84.2% vs IN 89.5% vs ILN 66.7%; P=0.30). Pathologic complete response (pCR) was higher among DCIS patients in comparison to the IBC patients (28.6% vs 8.3%). Among the DCIS patients, those who achieved pCR (N = 12) and who did not (n = 30) had similar peripheral blood anti-HER2 immune responses. Every patient who attained pCR had an anti-HER2 CD4 immune response in the sentinel lymph node. The quantified response was higher by cumulative response (P=0.04) and response repertoire (P=0.03).
The researchers concluded that the vaccination is a safe and immunogenic treatment for inducing tumor-specific T-cell responses in HER2-positive patients and that the immune and clinical responses were similar regardless of the vaccination route.