Qilu Pharma Unveils Phase II Clinical Data of PD-L1/4-1BB Bispecific Antibody QLF31907 in Heavily Pretreated Advanced Melanoma

2026 American Society of Clinical Oncology（ASCO）The conference is about to commence. According to the abstracts published on the official website of the ASCO Annual Meeting, Qilu Pharmaceutical will present for the first time at this conferencePD-L1/4-1BB Bispecific Antibody QLF31907 in Previously Treated Patients with Advanced MelanomaPhase II clinical trial data in.

Screenshot source: ASCO official website

QLF31907 is a bispecific antibody that simultaneously blocks the PD-1/PD-L1 immune inhibitory pathway on cancer cells and conditionally activates the 4-1BB costimulatory pathway on tumor-specific T cells. The antibody is designed to restrict the activity of the 4-1BB agonist to the tumor microenvironment, thereby potentially overcoming resistance to PD-(L)1 inhibitors and reducing the hepatotoxicity reported with conventional 4-1BB monoclonal antibodies.

Although immunotherapy (IO) While it has revolutionized the treatment of melanoma, a substantial proportion of patients, particularly those with mucosal and acral melanoma, either exhibit primary resistance to initial therapy or experience disease recurrence following treatment. This study, presented at ASCO, aims to evaluate QLF31907 in patients with previously treated advanced melanoma(including patients who have received immunotherapy)efficacy results in.

This Phase II clinical trial includes a safety observation period and an efficacy expansion phase. The study enrolled patients with unresectable locally advanced or metastatic melanoma who were refractory to, intolerant of, or declined standard therapy. Patients received QLF31907 via intravenous infusion at a dose of 5 mg/kg to 20 mg/kg every 2 weeks(Q2W) or 3 weeks (Q3W) Once.The primary endpoint is dose-limiting toxicity during the safety observation period. (DLT) and safety, and assessed by the investigator during the efficacy expansion phase according to RECIST v1.1 criteriaObjective Response Rate(ORR)。

As of December 31, 2025, a total of 59 patients were enrolled. The mucosal subtype was the most common.（40.7%）, followed by the acral type（33.9%）、Cutaneous type(Non-acral; 18.6%)and Cancer of Unknown Primary type（6.8%）The median number of prior lines of therapy was 2.0.(Range 1-5)55 cases.（93.2%）Patients who had previously received immunotherapy, of whom 50 cases（87.7%）Patients have previously received anti-PD-1/PD-L1 therapy.

The results showed that,No dose-limiting toxicity occurred（DLT）. 34 cases（57.6%）Patients experiencing Grade ≥3 treatment-emergent adverse events（TEAE）. Most common Grade ≥3 TEAEs（≥10%）is liver injury（18.6%）、Decreased neutrophil count（15.3%）、Anemia（13.6%）and decreased white blood cell count（11.9%）。

Among 57 patients evaluable for efficacy, 7 achieved a partial response. ORRis 12.3%(95% confidence interval [CI], 5.1%-23.7%),Disease Control Rate (DCR) was 56.1%（95% CI，42.4%-69.3%）. Median Progression-Free Survivalwas 2.6 months（95% CI，1.6-3.7），Duration of remission:5.8 months(95% CI, 2.3 to Not Estimable [NE])，Overall survival was 15.3 months.（95% CI，11.6-NE）。

Studies suggest QLF31907 in heavily pretreated patients with advanced melanoma(including immunotherapy-exposed patients)demonstrated potential antitumor activity and acceptable safety. These results require validation in further clinical trials.

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