Targeted breast cancer drug shows promise in early trial

PARP inhibitors can help treat advanced breast cancers carrying inherited BRCA mutations, but blood-related side effects remain a concern. Researchers tested TSL-1502, a prodrug designed to release its active ingredient more selectively around tumour tissue.

The phase-two study enrolled 63 women across 28 sites in China. An independent review found objective response rates of 55.6% with the 500mg dose, 36% with 350mg and 40% with chemotherapy. Median progression-free survival was 8.8 months, 5.6 months and 9.2 months respectively.

The results suggest tumour-activated medicines may offer another route for designing more targeted cancer treatments. For UK audiences, the wider lesson is that improving how a drug reaches cancer cells can be as important as discovering an entirely new active compound.

This was a small, open-label trial, with only 11 participants assigned to chemotherapy. Serious treatment-related side effects remained common, and the apparent response advantage did not produce longer median progression-free survival than chemotherapy. Larger randomised studies must now test effectiveness and safety.