Beijing, China, December 9, 2025 – Innovent Biologics (SSE: 688428; HKSE: 09969), a high-tech biopharmaceutical company, today announced that three studies of its novel BCL2 inhibitor, mesutoclax (ICP-248), were presented at the 67th American Society of Hematology (ASH) Annual Meeting. Mesutoclax demonstrated excellent efficacy and safety in studies treating relapsed/refractory mantle cell lymphoma (MCL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and acute myeloid leukemia (AML).

Studies of mesutoclax in the treatment of relapsed/refractory MCL were selected for oral presentations, and two studies of mesutoclax in the treatment of CLL/SLL and AML were selected for poster presentations.

oral report

Efficacy and tolerability of Mesutoclax monotherapy in patients with relapsed/refractory MCL: High response rate demonstrated in patients previously resistant to BTK inhibitors (Report No.: 887)

Mesutoclax monotherapy has demonstrated excellent efficacy in treating MCL patients, particularly in previously treated patients refractory to BTK inhibitors. The overall response rate (ORR) for MCL patients receiving 125 mg mesutoclax monotherapy was 87.5%, and the complete response rate (CRR) was 46.9% . In BTK inhibitor-refractory MCL patients, the ORR was 84.0%, and the CRR was 36.0%.

Mesutoclax was well tolerated at all dose levels (50 mg to 150 mg), with no dose-limiting toxicities (DLTs) observed and no maximum tolerated dose (MTD) reached.

Clinical data on mesutoclax monotherapy showed a good safety profile and potential best-in-class efficacy in MCL patients, especially those who have received extensive prior treatment and are resistant to BTK inhibitors.

Image source: Innovent Biologics

Poster display

1. Mesutoclax monotherapy or in combination with orelabrutinib showed encouraging efficacy and safety in the treatment of CLL/SLL (Report No.: 5677)

Mesutoclax monotherapy or in combination with orelabrutinib was well tolerated in all dose groups. Significant efficacy and deep remission were observed in treatment-naïve CLL/SLL patients receiving 125 mg mesutoclax in combination with orelabrutinib and in relapsed/refractory CLL/SLL patients receiving mesutoclax monotherapy.

In both treatment-naïve CLL/SLL and relapsed/refractory CLL/SLL (including patients who have failed previous BTK inhibitor therapy), the ORR in the 125 mg mesutoclax dose group was 100% . At 36 weeks of combined treatment with orelabrutinib, the rate of undetectable minimal residual disease (uMRD) in peripheral blood was 65% .

Mesutoclax monotherapy or in combination with orelabrutinib demonstrated a good safety profile. DLT was not observed and MTD was not reached when the dose was escalated to 150 mg mesutoclax once daily. Most treatment-emergent adverse events (TEAEs) during treatment were grade 1-2.

2. Safety, tolerability, and efficacy of mesutoclax in the treatment of AML (Report No.: 3417)

Mesutoclax in combination with azacitidine demonstrated encouraging antitumor activity in the treatment of acute myeloid leukemia (AML). The composite complete response rate (CR+CRi, cCR%) in newly diagnosed AML patients was 92%, and the untreated malignant tumor remission rate (uMRD) was 82.6% , with most newly diagnosed AML patients achieving composite complete response by the end of the first treatment cycle. More notably, 44% of the newly diagnosed AML patients in this study were high-risk patients, with a median age of 68 years.

Mesutoclax in combination with azacitidine also demonstrated a favorable safety profile for AML. No cases of tumor lysis syndrome (TLS) or tumor thrombosis syndrome (DLT) occurred throughout the study. No deaths occurred within 90 days of treatment initiation.

Mesutoclax further strengthens Innovent Biologics' hematologic oncology pipeline, with two registration clinical trials currently underway: one in combination with orelabrutinib for treatment-naïve CLL/SLL; and the other for MCL after BTK inhibitor resistance . In addition, clinical studies of Mesutoclax as first-line treatment for AML have entered the dose expansion phase in China and globally, and clinical studies for myelodysplastic syndromes (MDS) are being accelerated globally.

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