Kairos Pharma is moving prostate cancer prospect ENV-105 into an earlier line of treatment in response to midphase survival data.
Under the modified phase 2 protocol, Kairos will enroll patients whose PSA increases following upfront treatment with an androgen signaling inhibitor. Investigators will randomize patients who meet the new criteria to receive either Xtandi and ENV-105 or the Astellas-Pfizer blockbuster as a monotherapy. Kairos pitched the protocol as a way to expand the patient population and facilitate enrollment.
The previous protocol required patients to have received one or two antiandrogen agents. At an interim analysis, median progression-free survival (PFS) was 17.7 months in patients treated with ENV-105 plus apalutamide, an androgen receptor inhibitor that Johnson & Johnson sells as Erleada. Median PFS in the apalutamide monotherapy arm was two months.
Kairos’ statement doesn’t say how many patients received the treatments. The trial is designed to enroll 116 patients and features two parts. In September 2025, researchers shared results from the 10-patient safety lead-in part of the trial.
A physician at Cedars-Sinai Medical Center began the trial in 2023 to test whether inhibiting CD105 and the androgen receptor can restore hormone sensitivity. The CD105 receptor is upregulated in castration-resistant prostate cancer and further elevated by androgen receptor inhibition. Kairos has identified CD105 as a target for reversing drug resistance in indications including prostate cancer.
Kairos aims to complete the phase 2 trial by the fourth quarter of next year. The biotech ended June with $2.6 million in cash and short-term investments, a sum it warned may be insufficient to fund operations for the next 12 months.