SHR2554, an EZH2 inhibitor, in relapsed or refractory mature lymphoid neoplasms: a first-in-human, dose-escalation, dose-expansion, and clinical expansion phase 1 trial

Background: Dysregulation of EZH2 has a crucial role in lymphomagenesis. We did a first-in-human study to assess the safety, pharmacokinetics, pharmacodynamics, and preliminary clinical activity of SHR2554, an oral EZH2 inhibitor, in patients with relapsed or refractory mature lymphoid neoplasms, including B-cell lymphomas, T-cell lymphomas, and classical Hodgkin lymphoma.

Methods: This was a multicentre, dose-escalation, dose-expansion, and clinical expansion phase 1 study done at 13 hospitals in China. Eligible patients had histologically or cytologically confirmed mature lymphoid neoplasms that had relapsed or were refractory to standard systemic therapies or had no standard-of-care. The study included a dose-escalation phase, at doses of SHR2554 from 50 mg to 800 mg twice daily; a dose-expansion phase, at two selected doses; and a subsequent clinical expansion phase at the recommended phase 2 dose in selected tumours. Primary endpoints were the safety, maximum tolerated dose, and recommended phase 2 dose. Objective response rate was a secondary endpoint. Safety and activity were assessed in all patients who received at least one dose of SHR2554 and had at least one post-baseline evaluation. This study is registered with ClinicalTrials.gov, NCT03603951, and follow-up is ongoing.

Findings: Between Aug 14, 2018, and July 13, 2021, 113 patients received SHR2554. At data cutoff (Sept 10, 2021), the median follow-up duration was 7·0 months (IQR 3·7-12·0). 71 (63%) patients were men and 42 (37%) were women, 110 (97%) were of Han ethnicity and 3 (3%) of other ethnicities, and 53 (47%) had received three or more lines of previous anticancer therapies. Dose-limiting toxicities occurred in two (67%) of three patients who received 400 mg SHR2554 twice daily and one (17%) of six patients who received 350 mg SHR2554 twice daily. The maximum tolerated dose and recommended phase 2 dose was determined to be 350 mg twice daily. The most common grade 3 or 4 treatment-related adverse events in all 113 patients were decreased platelet count (20 [18%]), decreased neutrophil count (ten [9%]), decreased white blood cell count (nine [8%]), and anaemia (seven [6%]). 18 (16%) patients had serious treatment-related adverse events. Two patients (2%) died due to treatment-related adverse events: one (1%) due to skin infection and toxic epidermal necrolysis and one (1%) due to respiratory failure. 107 (95%) of the 113 enrolled patients had post-baseline assessments for tumour response and were included in the activity analysis. 46 (43%; 95% CI 33-53) of these 107 patients had an overall response.

Interpretation: SHR2554 showed an acceptable safety profile and promising antitumour activity in patients with relapsed or refractory lymphomas, providing evidence for future investigations.

Funding: Jiangsu Hengrui Pharmaceuticals.

Translation: For the Chinese translation of the abstract see Supplementary Materials section.