Valemetostat monotherapy in patients with relapsed or refractory non-Hodgkin lymphoma: a first-in-human, multicentre, open-label, single-arm, phase 1 study

Few treatment options exist for patients with non-Hodgkin lymphoma, and outcomes remain poor for relapsed or refractory disease. We evaluated the safety and preliminary clinical activity of valemetostat, a novel inhibitor of EZH2 and EZH1, in patients with relapsed or refractory non-Hodgkin lymphomas. This first-in-human, multicentre, open-label, single-arm, phase 1, dose-escalation and dose-expansion trial was done in 19 hospitals across Japan and the USA. Patients were included if they were aged 18 years or older in the USA or 20 years or older in Japan with a primary diagnosis of relapsed or refractory non-Hodgkin lymphoma and an Eastern Cooperative Oncology Group performance status of 0 or 1. In the dose-escalation part, patients received oral valemetostat at doses of 150 mg per day, 200 mg per day, 250 mg per day, and 300 mg per day continuously in 28-day cycles until progressive disease or unacceptable toxicities. All patients received 200 mg per day in the dose-expansion part. The primary endpoints were safety, pharmacokinetics, and the recommended phase 2 dose; the secondary endpoints were the maximum tolerated dose and the antitumour activity of valemetostat. Responses were assessed in patients who received at least one dose, with measurable lesions at baseline according to the International Working Group 2007 revised criteria for malignant lymphoma (peripheral T-cell lymphoma and B-cell non-Hodgkin lymphoma) and the modified 2009 criteria for adult T-cell leukaemia/lymphoma. The trial is registered with ClinicalTrials.gov, NCT02732275, and is currently active, but not recruiting. Between April 7, 2016, and June 10, 2021, 90 patients (53 [59%] males and 37 [41%] females; 49 [54%] Asian, 33 [37%] White, and eight [9%] Black) were enrolled and treated with valemetostat and included in the safety analysis set. 57 (63%) patients had peripheral T-cell lymphoma, 14 (16%) had adult T-cell leukaemia/lymphoma, and 19 (21%) had B-cell non-Hodgkin lymphoma. Seven (8%) patients received valemetostat 150 mg per day, 74 (82%) received 200 mg per day, seven received 250 mg per day, and two received 300 mg per day. Median follow-up was 7·4 months (IQR 3·4–17·6). All patients had at least one treatment-emergent adverse event; the most common treatment-emergent adverse events of any grade were decreased platelet count (52 [58%] of 90 patients), dysgeusia (45 [50%]), and anaemia (38 [42%]). The most common grade 3–4 adverse events were decreased neutrophil count (21