CHICAGO (FRONTLINE MEDICAL NEWS) – Investigational agent PT2385, an inhibitor of hypoxia-inducible factor 2-alpha (HIF-2alpha), appears safe and tolerable and demonstrated early evidence of clinical activity in heavily pretreated patients with advanced clear cell renal cell carcinoma, investigators reported at the annual meeting of the American Society of Clinical Oncology.

In a small, phase I dose-escalation study, 39% of patients in the study achieved complete response, partial response, or stable disease lasting at least 16 weeks.

PT2385 is a first-in-class, orally administered selective small molecule inhibitor of HIF-2alpha, a transcription factor with a role in clear cell renal cell carcinoma.

“Hypoxia-inducible factor 2-alpha is a key oncogenic driver of clear cell renal cell carcinoma,” Kevin Courtney , MD, PhD, of the University of Texas Southwestern Medical Center, Dallas, said at the meeting.

A total of 51 patients (n = 26 for dose escalation cohort and n = 25 in dose expansion cohort) met the study’s eligibility requirements of having a diagnosis of clear cell renal cell carcinoma, an Eastern Cooperative Oncology Group score ranging from 0 to 1, and at least one prior anticancer therapy. The median age of the cohort was 65 years with the youngest participant being 29 years and the oldest being 80 years old. The majority of patients were male (71%), had received four or more prior systemic therapies (53%), and had undergone vascular endothelial growth factor therapy (98%). Patients were treated with continuous twice-daily oral dosing of PT2385 until progression or toxicity. A total of three patients were treated at the 100-mg dose, three at the 200-mg dose, four at the 400-mg dose, seven at the 800-mg dose, six at a dose of 1,200 mg, and three at a dose of 1,800 mg.

“No dose-limiting toxicity was observed at any dose level,” Dr. Courtney said.

Based on safety, pharmokinetic and pharmodynamic data, 800 mg twice daily was the selected dose for the expansion cohort, he reported.

Of 51 patients treated, 1 patient had a complete response, 3 achieved partial responses, and 16 patients achieved stable disease for at least 16 weeks. The most common grade one or two adverse events were anemia (n = 18), peripheral edema (n = 18), fatigue (n = 18), nausea (n = 15), and back pain (n = 12). Only two grade four adverse events (low lymphocyte count) were reported.

“Notably, hypertension was not seen,” Dr. Courtney said.

At the time the study concluded, the four patients who achieved complete or partial responses remained on the treatment, and five had received treatment for a year or longer.

The study was funded by Peloton Therapeutics. Dr. Courtney reported having stock and ownership interest in, serving in advisory roles for, or receiving research funding from multiple companies. Several coinvestigators reported receiving research funding from or holding patents with multiple companies including Peloton Therapeutics.

On Twitter @jessnicolecraig


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