US-based biotechnology firm Arvinas has reported positive data from the ongoing Phase I clinical trials of its cancer drug candidates, ARV-110 and ARV-471.

Based on the company’s PROTAC platform, ARV-110 and ARV-471 are protein degrader products that target the androgen receptor (AR) and the oestrogen receptor (ER), respectively.

The open-label, dose-escalation Phase I trials of the drug candidates are designed to assess safety, tolerability and pharmacokinetics, along with anti-tumour activity and pharmacodynamics.

ARV-110’s study involves 28-36 metastatic castration-resistant prostate cancer (mCRPC) patients who have progressed on a minimum of two previous systemic therapies.

The trial assessing ARV-471 will enrol 24-36 participants suffering from oestrogen receptor-positive (ER+) / human epidermal growth factor receptor-2 negative (HER2-) locally advanced or metastatic breast cancer.

ARV-471 will be tested in patients who had prior hormonal therapy and chemotherapy.

Initial trial results indicated that both the drugs are well tolerated across the doses evaluated, without any dose-limiting toxicities (DLTs) or grade 2, 3, or 4 adverse events.

ARV-110 data is from the first three dose-escalation cohorts assessing 35mg, 70mg and 140mg doses. The company also reported dose-proportional exposures of the drug.

For ARV-471, the results are from three patients in the 30mg dose cohort.

Arvinas CEO John Houston said: “We are seeing a favourable overall safety profile for both clinical programs to date, and dose-proportional exposures of ARV-110.

“We are encouraged by these initial results as we work to create well-tolerated therapies to treat serious diseases.”

The company will increase the dose of ARV-110 to 280mg and that of ARV-471 to 60mg in the next cohorts. Additional data from the Phase I trials is expected to be available next year.