Sumitomo Dainippon Pharma Oncology (SDP Oncology) has dosed the first subject in the Phase I/II clinical trial of its therapy DSP-5336 in relapsed or refractory (r/r) acute myeloid leukaemia (AML) or acute lymphocytic leukaemia (ALL) patients.

DSP-5336 is a small molecule inhibitor of menin binding to mixed-lineage leukaemia (MLL) protein.

The open-label trial will have dose-escalation and dose-expansion parts.

Evaluating DSP-5336’s safety and tolerability in r/r AML or ALL patients and selecting the recommended Phase II dose (RP2D) are the primary objectives of the Phase I dose-escalation segment of the trial.

Analysing the initial clinical activity of DSP-5336 in adult patients will be included as a secondary objective.

On concluding the Phase I portion, the trial will advance into the Phase II dose expansion portion of the study.

To further assess the safety and clinical activity of DSP-5336 in adult r/r AML patients with MLL rearrangement or nucleophosmin 1 (NPM1) mutation is the primary objective of this portion of the trial.

Sumitomo Dainippon Pharma Oncology CEO, Oncology global head Patricia Andrews said: “Patients with refractory or relapsed AML or ALL have an unfavourable prognosis and respond poorly to available treatments.

“Dosing the first patient in our Phase I/II study is an important milestone as we evaluate DSP-5336 and its safety and potential benefits for this patient population.

“It is our hope that the data generated by this study furthers our goal of advancing meaningful treatments for patients with blood cancer.”

According to preclinical data, disruption of fusion and wild-type menin-MLL interactions hinders leukemic cell multiplication and reinstates terminal differentiation of MLL-rearranged and NPM1–mutated leukemic cells.

DSP-5336 is said to attach to menin to MLL fusion and wildtype proteins leading to the upregulation of HOXA family and MEIS1 genes that act in stopping myeloid cellular differentiation and elicit leukemogenic transformation.