LEPU BIOPHARMA and HANX BIOPHARMACEUTICALS announced that Anti-PD-1 monoclonal antibody – PuyouhengTM (HX-008, pucotenlimab injection), was conditionally approved by the National Medical Products Administration (NMPA) for marketing in China to treat patients with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) advanced solid tumors, specifically: Patients with advanced colorectal cancers have progressed following previous treatment with a fluoropyrimidine, oxaliplatin and irinotecan; Patients with other advanced solid tumors that have progressed following at least previous first-line therapy with no satisfactory alternative treatment options. The approval is based on a multi-center, open-label, phase II clinical study with a primary study endpoint of the objective response rate (ORR) assessed by the Independent Review Committee (IRC) according to the RECIST1.1. As of December 4, 2021, a total of 100 patients with histologically confirmed advanced solid tumors that are identified as having MSI-H/dMMR by the central Laboratory were enrolled in the study. They were given 200 mg of pucotenlimab by intravenous drip every 3 weeks (Q3W).

The median follow-up duration for the ITT population was 22.5 months. And the ORR for the ITT population was 49.0% (95% CI: 38.86%, 59.20%), with 9 cases of complete response (CR) and 40 cases of partial response (PR). In the subgroup of patients with colorectal cancers who had failed previous triplet therapy (a fluoropyrimidine, oxaliplatin, and irinotecan), the ORR was 50.0% (95% CI: 31.30%, 68.70%).

The results of the study showed that pucotenlimab monotherapy was safe and effective in patients with unresectable or metastatic MSI-H/dMMR advanced solid tumors who have failed previous standard therapy. The expected clinical endpoints were achieved, indicating that patients can benefit significantly from the therapy. The results of the clinical study were first published at the 2021 American Society of Clinical Oncology (ASCO) annual meeting.

About Puyouheng (HX-008, pucotenlimab injection): Puyouheng (pucotenlimab injection) is a humanized IgG4 monoclonal antibody against human PD-1 discovered by HanX Biopharmaceuticals, It can bind to PD-1 with high affinity to restore the ability of immune cells to kill cancer cells by blocking the binding of PD-1 to its ligands PD-L1 and PD-L2. Puyouheng (pucotenlimab injection) adopts an innovative molecular design to prolong its half-life, showing strong clinical anti-tumor activity and good safety. The innovative use of antibody engineering technology to introduce triple mutations in the Fc region improves the binding affinity of FcRn, thereby prolonging the drug's half-life significantly, showing its promising clinical efficacy and drug compliance in patients [5].

Compared with all rival anti-PD-1 antibodies that have been marketed or entered phase III clinical trials, the mean half-life of Puyouheng (pucotenlimab injection) is 21.8 days (single dosing) and 38.2 days (steady-state). In addition, the prolonged half-life does not cause additional adverse events, indicating the excellent clinical efficacy of the drug.