I-Mab: Positive Phase 2 Data of Lemzoparlimab Combo with Azacitidine in Myelodysplastic Syndrome

 I-Mab announced encouraging data from its Phase 2 clinical trial (NCT04202003) of lemzoparlimab (also known as TJC4) in combination with azacitidine (AZA) in patients with newly diagnosed higher risk myelodysplastic syndrome (HR-MDS), presented in an oral presentation on September 10 at the European Society for Medical Oncology (ESMO) Congress 2022.  The open-labeled Phase 2 clinical trial is designed to investigate the efficacy and safety of lemzoparlimab in combination with AZA in patients with newly diagnosed HR-MDS. A total of 53 patients were enrolled as of March 31, 2022, receiving lemzoparlimab at a weekly dose of 30 mg/kg intravenously (IV) and AZA at 75 mg/m2 subcutaneously (SC) on Days 1–7 in a 28-day cycle. Top-line data showed that for patients who began treatments 6 months or longer prior to the analysis (n=15), the overall response rate (ORR) and complete response rate (CRR) was 86.7% and 40% respectively.

For patients who began treatment 4 months or longer prior to the analysis (n=29), the ORR and CRR was 86.2% and 31% respectively. While the study enrolled more patients with worse baseline conditions due to underlying disease (74% of patients had grade =3 anemia and 51% of patients had grade =3 thrombocytopenia), the results showed that lemzoparlimab combined with AZA was well-tolerated and the safety profile was consistent with AZA monotherapy. Decreased red blood cells, measured as hemoglobin, and decreased platelets are major causes of morbidity for patients with HR-MDS and the median hemoglobin and platelet levels for patients on study increased in response to treatment. Of the 29 patients who were dependent upon blood transfusions at baseline, 9 patients (31%)  became transfusion independent at the time of analysis. Furthermore, the majority of CR patients showed reduction in variant allele frequency (VAF) of MDS-related gene mutation including TP53, TET2 and RUNX1, with 56% achieving minimal residual disease negativity (=10-4) by flow cytometry. These data are consistent with the anti-leukemic activities and expected drug safety of lemzoparlimab.

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