Giving chemotherapy on the same day as a cancer vaccine may strengthen the immune response. The finding comes from preclinical models. It was published in the journal Cancer Cell.

Researchers found that chemotherapy expanded a pool of stem-like TCF1-positive CD8-positive T cells. These immune cells are key to fighting tumours. The expansion happened independently of vaccination. It created a deep pool of T cells ready to respond when the vaccine antigen arrived later.

The team also saw the same T-cell expansion in samples from two groups of cancer patients. These patients had been treated with CarboTaxol, a common chemotherapy combination. This supports the clinical relevance of the finding.

Study author Van den Eynde said the results could reshape cancer vaccine trials. Current studies may be missing an adjuvant effect from timing alone. The work points to testing the best interval between chemotherapy and vaccination. The mechanism may also extend to other immunotherapy combinations.