Xilio shares tumble after mixed vilastobart data

Xilio Therapeutics (Nasdaq: XLO) has reported initial results from its Phase II trial of vilastobart, an anti-CTLA-4 therapy, in combination with Roche's (ROG: SIX) Tecentriq (atezolizumab).

The trial is testing the combo as an option for certain people with colorectal cancer. Presented at a meeting of the American Society of Clinical Oncology, the mixed results appeared to worry investors on Wednesday, sending shares down by around a third.

The trial involved 40 patients, 70% of whom had undergone at least three prior lines of anti-cancer therapy. One positive sign was an objective response rate (ORR) of 27% from a subset of patients, including three partial responses.