Transcenta Holding Limited, a global biotherapeutics company announced that the updated phase I clinical study (NCT04272944) data on the safety and efficacy of MSB2311, a pH-dependent PD-L1 antibody, in Chinese patients with advanced solid tumors and hematological malignancies have been presented as an abstract online publication at the 2021 Annual Meeting of the American Society of Clinical Oncology (ASCO).

The study, presented at the 2021 ASCO annual meeting by abstract, was led by Professor Lin Shen from Beijing Cancer Hospital, and was a Phase I study of MSB2311 with a unique pH-dependent antigen binding property in Chinese patients with advanced solid tumors and lymphoma. Its primary objectives were to evaluate the safety and tolerability and to identify the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). The secondary objectives included the assessment of pharmacokinetic parameter, immunogenicity, and preliminary anti-cancer activity per RECIST version 1.1.

The study included a dose escalation phase and a dose expansion Phase. In the dose escalation phase, MSB2311 was given at dose levels of 3, 10, and 20mg/kg intravenously every 3 weeks. At the dose expansion phase, patients with biomarker expression, including EBV+, PD-L1+ (TPS=50%), MSI-High or TMB-High (=10muts/Mb), were dosed at 20mg/kg Q3W or 10mg/kg Q2W.

As of data cutoff by Aug 31, 2020, 33 Chinese patients had been treated, including 27 heavily pre-treated solid tumor patients and 6 lymphoma patients. No dose limiting toxicity was reported and MTD has not been reached.

Of the 17 efficacy evaluable solid tumor patients with biomarker expression, 6 achieved confirmed partial response with an ORR of 35%: 2/8 (25%) at 10mg/kg Q2W and 4/9 (44%) at 20mg/kg Q3W. Additionally, one patient achieved sustained iPR per iRECIST. 4 out of 7 responding patients (including one iPR) achieved tumor shrinkage of more than 50%, 3 of them got durable response (=24 weeks). 1 out of 6 lymphoma patients achieved PR.

"In recent years, tumor immunotherapy has gradually become a research hotspot in the field of tumor treatment. It has played a great role in the treatment of tumors, and we have been making efforts in this area," said Professor Lin Shen, the leading investigator from Beijing Cancer Hospital. "Patients with metastatic solid tumors or selected lymphoma progressed on or after standard treatments were enrolled in this Phase I study. This phase I study showed promising preliminary efficacy and tolerability of MSB2311 in patients with advanced solid tumors and hematological malignancies."