Daiichi Sankyo has dosed the first patient in a Phase II study to evaluate the efficacy and safety of valemetostat (DS-3201) in patients with relapsed/refractory adult T-cell leukemia-lymphoma (ATL).

The first patient for the pivotal trial of valemetostat was dosed in Japan.

Valemetostat is an investigational EZH1/2 dual inhibitor that targets epigenetic regulation by inhibiting the EZH1, as well as EZH2 enzymes, which regulate gene expression by acting through histone methylation.

The open-label, multi-centre, single-arm Phase II study will evaluate valemetostat as a monotherapy in patients with ATL who were treated with mogamulizumab or at least one systemic chemotherapy.

Daiichi Sankyo initiated the trial based on preliminary findings from an ongoing Phase I study in patients with several types of NHL.

Valemetostat is evaluated in Phase I clinical development for several types of NHLs, including ATL, peripheral T-cell lymphoma (PTCL) and B-cell lymphomas. Patients are currently being enrolled for the trial in the US and Japan.

Daiichi Sankyo Oncology Clinical Development Department, Oncology Function Valemetostat global team leader Kaszushi Araki said: “Valemetostat is a novel targeted therapy that has demonstrated preliminary potential in several types of NHL, including ATL, which represents one of the greatest areas of need among lymphoma patients, particularly in Japan.

“Valemetostat is the only EZH1/2 dual inhibitor in clinical development, and our programme includes translational research to improve understanding of underlying disease mechanisms and treatment response.”

The study’s primary efficacy endpoint is overall response rate (ORR). Investigator-assessed ORR, complete remission rate, time to response, duration of response, progression-free survival and overall survival are the secondary endpoints.

Safety endpoints including adverse events and a number of pharmacokinetic, pharmacodynamic and biomarker endpoints will be evaluated as part of the study.

For this trial, the company is expected to enrol about 25 patients in Japan.