Valemetostat for patients with relapsed or refractory peripheral T-cell lymphoma (VALENTINE-PTCL01): a multicentre, open-label, single-arm, phase 2 study

Background: Peripheral T-cell lymphomas are aggressive non-Hodgkin lymphomas with few treatment options for relapsed or refractory disease. Valemetostat tosylate (valemetostat) is a potent, novel, dual inhibitor of EZH2 and EZH1. We investigated the clinical activity and safety of valemetostat in patients with relapsed or refractory peripheral T-cell lymphoma, and its safety in patients with relapsed or refractory adult T-cell leukaemia/lymphoma.

Methods: VALENTINE-PTCL01 was a multicentre, open-label, single-arm, phase 2 trial performed at 47 hospitals in 12 countries across Asia, Europe, North America, and Oceania. Patients with either peripheral T-cell lymphoma or adult T-cell leukaemia/lymphoma, aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0-2 received oral valemetostat at 200 mg per day in continuous 28-day cycles until disease progression or unacceptable toxicity. The primary endpoint for patients with peripheral T-cell lymphoma was the CT-based objective response rate by blinded independent central review (BICR) using 2014 Lugano response criteria. Patients who received valemetostat and had a confirmed eligible peripheral T-cell lymphoma subtype on central review were included in the efficacy analysis. The primary endpoint for patients with adult T-cell leukaemia/lymphoma was the safety and tolerability of valemetostat. Safety in both cohorts was assessed in all patients who received at least one dose of valemetostat. The trial is registered with ClinicalTrials.gov, NCT04703192, and EudraCT, 2020-004954-31, and is closed to enrolment.

Findings: Between June 16, 2021, and Aug 10, 2022, 133 patients with relapsed or refractory peripheral T-cell lymphoma (median age 69·0 years [IQR 58·0-74·0]; 91 [68%] were male, and 42 [32%] were female) and 22 patients with adult T-cell leukaemia/lymphoma (66·5 years [54·0-73·0]; 15 [68%] were male, and seven [32%] were female) were enrolled. The median follow-up time was 12·3 months (95% CI 11·8-13·8). 52 (44%; 95% CI 35-53) of 119 efficacy-evaluable patients with relapsed or refractory peripheral T-cell lymphoma had an objective response. The most common grade 3-4 adverse events were thrombocytopenia (31 [23%] of 133 patients in the peripheral T-cell lymphoma group and 11 [50%] of 22 patients in the adult T-cell leukaemia/lymphoma group), anaemia (25 [19%] and ten [46%]), and neutropenia (23 [17%] and four [18%]). Serious treatment-emergent adverse events were reported in 53 (40%) patients with peripheral T-cell lymphoma and 15 (68%) patients with adult T-cell leukaemia/lymphoma; nine (7%) patients and one (5%) patient had a serious treatment-emergent adverse event considered to be treatment related, respectively. No treatment-related deaths were reported.

Interpretation: These data show that treatment with valemetostat leads to durable responses in patients with relapsed or refractory peripheral T-cell lymphoma, with a manageable safety profile.

Funding: Daiichi Sankyo.