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The Pivotal Trial Results for the Treatment of MSI-H/dMMR Solid Tumors of Anti-PD-1 mAb Serplulimab Released at 2022 ASCO Annual Meeting

2022-06-06

Shanghai, China, June 6th, 2022 –Shanghai Henlius Biotech, Inc. (2696.HK) announced that the updated results from the phase 2 study (ASTRUM-010) of company’s self-developed innovative anti-PD-1 mAb, HANSIZHUANG (serplulimab), in patients with microsatellite instability-high or mismatch repair-deficient (MSI-H/dMMR) solid tumors was released in the form of poster at 2022 American Society of Clinical Oncology (ASCO) Annual Meeting for the second time. ASTRUM-010 was co-led by Professor Shukui Qin from Qinhuai Medical Area, Eastern Theater General Hospital of PLA China and Professor Jin Li from Shanghai East Hospital, Tongji University. Based on the study results of ASTRUM-010, serplulimab has been approved for the treatment of microsatellite instability-high (MSI-H) solid tumors by NMPA.


It is estimated that there are more than 300,000 new MSI-H tumor patients in China every year. MSI-H is commonly found in endometrial cancer, colorectal cancer, and gastric cancer, etc. These patients usually have high response to immune checkpoint inhibitors. PD-1/PD-L1, important immunosuppressive molecules, have good therapeutic effect for patients with MSI-H solid tumors. The clinical trial of ASTRUM-010 conducted by Henlius  was based on MSI-H indication. The results of ASTRUM-010 have been presented at the 2021 ASCO annual meeting and the 2021 CSCO annual meeting. Its updated data at 2022 ASCO are as follows:


Titile

Updated efficacy and safety results from the phase 2 study of serplulimab, a novel anti-PD-1 antibody, in patients with previously treated unresectable or metastatic MSI-H/dMMR solid tumors (Abstract No. 2592)


Study design

This single-arm, open-label, multicenter, phase 2 study aimed to evaluate the efficacy, safety, and tolerability of serplulimab in patients with unresectable or metastatic MSI-H/dMMR solid tumors who had progressed on or were intolerant to standard therapies. Eligible patients were enrolled to receive 3 mg/kg serplulimab every two weeks intravenously for up to two years or until disease progression, unacceptable toxicity, or patient withdrawal. The primary endpoint was objective response rate (ORR) assessed by IRRC per RECIST v1.1. Secondary endpoints included ORR assessed by the investigators, duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety.


Results

As of July 10, 2021, 108 patients were enrolled and included in the safety set (SS). Sixty-eight patients with MSI-H confirmed by local study sites or central laboratory were included in the main efficacy analysis population (MEAP); 58 patients with MSI-H confirmed by central laboratory and had no major protocol deviations were included in the sensitivity analysis population (SAP). The median follow-up duration was 13.5 months in the MEAP and 14.0 months in the SAP.


IRRC-assessed ORR per RECIST v1.1 was 39.7% (95% CI 28.0–52.3; 3 complete response [CR]) in the MEAP and 43.1% (95% CI 30.2–56.8; 2 CR) in the SAP. Median DOR, PFS, and OS were not reached; 12-month OS rate was 74.5% in the MEAP and 82.4% in the SAP.


In the SS, 57 (52.8%) patients reported grade ≥3 treatment emergent adverse events (TEAEs), most commonly anemia (9.3%). Thirteen (12.0%) patients had grade ≥3 immune-related adverse events (irAEs). No new safety signal was observed.



Conclusions

In conclusion, the encouraging antitumor activity and the manageable safety profile sustained over a longer duration of follow-up, supporting serplulimab as an effective tissue-agnostic antitumor drug.