Zhixiang Jintai's GR1803 Clinical Trial Abstract Selected for Presentation at EHA 2024 Congress

The 29th European Hematology Association (EHA) Congress in 2024 will be held in Madrid, Spain, from June 13 to 16. As the largest international conference in the field of hematology in Europe, the EHA Congress covers all aspects of hematological research and attracts more than 10,000 professionals from over 100 countries worldwide each year to share the most cutting-edge research advances and breakthrough clinical data.

The Phase I clinical study results of GR1803 injection (recombinant humanized anti-BCMA×CD3 bispecific antibody) as monotherapy for patients with relapsed/refractory multiple myeloma, led by Professor Jin Jie from the First Affiliated Hospital, Zhejiang University School of Medicine, and Professor Chen Wenming from Beijing Chaoyang Hospital, Capital Medical University, will be presented in poster format at this conference.

GR1803 is a recombinant humanized anti-BCMA×CD3 bispecific antibody independently developed by GENRIX BIO for the treatment of relapsed/refractory multiple myeloma (RRMM). It is classified as a Class 1 therapeutic biological product, with BCMA and CD3 as its targets.GR1803 received the Notice of Approval for Drug Clinical Trials from the National Medical Products Administration in January 2022, authorizing clinical trials for the indication of multiple myeloma.

GR1803 can simultaneously bind to the antigens BCMA and CD3, with an affinity for BCMA of (10^-10M) Affinity for CD3 binding (10^-8M) by two orders of magnitude. This asymmetric affinity design ensures that the bispecific antibody molecule recruits and activates T cells to kill tumor cells, while effectively reducing non-specific T cell activation caused by the CD3 antibody, thereby lowering the in vivo toxic side effects of GR1803.

A Phase I Clinical Study to Evaluate the Safety, Pharmacokinetics, Immunogenicity, and Preliminary Efficacy of Single and Multiple Doses of GR1803 Injection in Patients with Relapsed/Refractory Multiple Myeloma.

Patients with relapsed/refractory multiple myeloma (RRMM) who had previously received treatment with proteasome inhibitors, immunomodulatory drugs, and CD38 monoclonal antibodies received intravenous infusions of GR1803 once weekly for a duration of 52 weeks. As of January 30, 2024, the dose-escalation study had been completed, along with the cohort expansion study for two dose groups (180 µg/kg and 240 µg/kg). A total of 50 subjects were enrolled, including 16 in the dose-escalation study and 34 in the cohort expansion study.

A total of 40 subjects have completed at least one efficacy assessment.The overall objective response rate (ORR) was 85% (34/40) in 40 evaluable subjects., the vast majority of patients in remission remained on continuous treatment, with a maximum follow-up duration of 44 weeks.

A total of 25 subjects were enrolled in the 180 µg/kg dose group, with a median follow-up time of 15 weeks (range: 3–32 weeks).Among them, 23 subjects completed at least one efficacy assessment, with an overall response rate (ORR) of 96% (22/23). The rate of very good partial response (VGPR) or better was 43%, and the rate of complete response (CR) or better was 13%.

The median follow-up time for the 13 subjects with baseline extramedullary plasmacytoma (EMM) in the 180 µg/kg dose group was 20 weeks (range: 10–25 weeks),Overall Efficacy Assessment: ORR was 100% (13/13), including 7 cases of VGPR and 6 cases of PR.

Most patients achieved a partial response (PR) or better at the first efficacy assessment, with a median time to response of 3 weeks. The responses in subjects were durable, and the depth of response continued to improve with ongoing treatment. For patients who had not yet responded (stable disease [SD] or minimal response [MR]), or those who achieved PR but had not yet reached very good partial response (VGPR) or better, all efficacy metrics showed a downward trend. The median progression-free survival (mPFS) and median duration of response (mDOR) were not reached in the 25 patients, and no disease progression was observed among all responding subjects.

As of January 31, 2024, the most common treatment-emergent adverse events (TEAEs) included cytokine release syndrome (CRS), neutropenia, infection, and anemia.

The study results indicate that GR1803 injection demonstrates significant antitumor activity in relapsed/refractory multiple myeloma. It is effective in patients with multiple myeloma (MM) who have received at least three prior lines of therapy, as well as in patients with extramedullary multiple myeloma (EMM). Compared with existing treatments and other investigational or marketed drugs targeting the same mechanism, GR1803 significantly improves the overall response rate (ORR) and markedly enhances disease prognosis.Meanwhile, with the extension of follow-up time, more efficacy and safety data will be provided.

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Source:EHA Official Website

https://library.ehaweb.org/eha/2024/eha2024-congress/421025/jie.jin.a.phase.i.monotherapy.study.assessing.the.safety.and.efficacy.of.html?f=menu%3D6%2Abrowseby%3D8%2Asortby%3D2%2Ace_id%3D2552%2Aot_id%3D29201%2Amarker%3D5101