What it is
Researchers gave an individualized neoantigen mRNA vaccine to 14 patients with triple-negative breast cancer following surgery and neoadjuvant or adjuvant therapy. In nearly all patients, high-magnitude, mostly de novo T cell responses to multiple neoantigens appeared and remained functional for several years, with a large proportion of these T cells developing into two subsets: ready-to-act cytotoxic effector cells and stem cell-like memory cells. Eleven patients remained relapse-free for up to six years after vaccination. Recurrence occurred in three patients, including the individual with the weakest vaccine-induced T cell response, who then achieved complete remission on subsequent anti-PD-1 therapy.
Why it matters
Triple-negative breast cancer has few targeted options, and whether a personalized cancer vaccine can raise neoantigen-specific T cell immunity that persists rather than fading has been unclear. Here the responses stayed functional for several years across 14 patients, documenting durable vaccine-induced immunity in this setting.
How to read this
It demonstrates the feasibility of individualized RNA vaccines in TNBC and, through the three patients who relapsed, points to possible immune escape routes (a weak response, low MHC class I expression) that future vaccine designs will need to address.
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