Subgroup analysis of nelipepimut S plus GM CSF combined with trastuzumab versus trastuzumab alone to prevent recurrences in patients with high risk, HER2 low expressing breast cancer.
HER2 targeted therapy has not benefited patients with low levels of HER2 expression; however, combination therapy may be effective. Primary analysis of a phase IIb trial investigating the HER2 derived vaccine nelipepimut S (NPS) did not benefit the intention to treat population, but subset analysis showed a benefit in triple negative breast cancer (TNBC) patients. The subset analysis of this multicenter, randomized, single blind, phase IIb trial identified significant improvement in 36 month disease free survival (DFS) between NPS (n 55) and placebo (n 44) in TNBC (HR 0.25, p 0.01) and those who express HLA A24 (HR 0.41, p 0.05) The TNBC cohort demonstrated improved 36 month DFS in those with HER2 1+ expression (HR 0.17, p 0.01) HLA A24 positivity (HR 0.08, p 0.01) or in those who received neoadjuvant chemotherapy (HR 0.21, p 0.01) NPS vaccination with trastuzumab was associated with improved 36 month DFS among patients with TNBC. The observed benefit to this high risk subgroup warrants confirmation in a phase III trial.
Clinical immunology