Qilu Pharmaceutical Reports Updated Clinical Data for B7-H3 ADC QLC5508 (MHB088C) in Extensive-Stage Small Cell Lung Cancer at WCLC 2025 Following $1.85 Billion Licensing Deal

On August 13 local time, the main text of the regular abstract for the 2025 WCLC conference was released. Qilu Pharmaceutical Co., Ltd. announced its B7-H3 ADC product at the conference. QLC5508（MHB088C）TreatmentExtensive-Stage Small Cell Lung Cancer（ES-SCLC）The latest clinical research data.

Source: WCLC 2025 Official Website

QLC5508 is a novel B7-H3 ADC. In May this year, Qilu Pharmaceutical Co., Ltd.RMB 1.345 billionThe price was introduced by Minghui Pharmaceuticals for the Greater China rights to the product. Preliminary data from the Phase I study indicate that QLC5508 has demonstrated favorable anti-tumor activity and tolerability in patients with solid tumors, including ES-SCLC. This time, Qilu Pharmaceutical reported the latest results on survival and safety in ES-SCLC patients.

This multicenter Phase I study includesDose Escalation Phase and Dose Expansion PhaseDuring the dose escalation phase, QLC5508 was administered via intravenous infusion at doses ranging from 0.8 mg/kg to 4.0 mg/kg.Every two weeks（Q2W）Or every three weeks（Q3W）. The dose expansion phase enrolled ES-SCLC patients who failed platinum-based chemotherapy ± PD-1/PD-L1 treatment, with no more than three prior lines of therapy or intolerance to standard treatment. Dose levels of 1.6 mg/kg Q2W, 2.0 mg/kg Q2W, and 2.4 mg/kg Q3W were selected for the dose expansion phase. The primary endpoints were safety and tolerability.

As of June 13, 2025,A total of 106 patients were enrolled.`, with dose levels of`1.6 mg/kg Q2W（n=30）、2.0 mg/kg Q2W（n=46）And 2.4 mg/kg Q3W（n=30）. Most patients（90.6%）Stage IV. The numbers of patients who had received second-line, third-line, and beyond third-line treatments were 28 cases, respectively.（26.4%）, 15 cases（14.2%）And 7 cases（6.6%）. More than half of the patients（58.5%）Received immunotherapy. 11 cases（10.4%）The patient had previously received irinotecan treatment.

The results showed that there were 15 cases in the 1.6 mg/kg Q2W, 2.0 mg/kg Q2W, and 2.4 mg/kg Q3W groups, respectively.（50.0%）, 16 cases（34.8%）And 13 cases（43.3%）The patient experienced ≥ Grade 3 treatment-related adverse events. (TRAE). The most common ≥3 TRAEs wereDecreased neutrophil count（17.0%）AndDecreased White Blood Cell Count（10.4%）. Two cases（4.3%）Patients discontinued treatment due to interstitial lung disease, all from the 2.0 mg/kg Q2W group. One patient (3.3%) in the 1.6 mg/kg group died due to treatment-related cachexia.

In terms of efficacy, the 1.6 mg/kg Q2W, 2.0 mg/kg Q2W, and 2.4 mg/kg Q3W groupsThe median progression-free survival was 5.55 months, 5.95 months, and 5.52 months, respectively.The total survival periods for the three cohorts were 11.50 months, 11.73 months, and 11.50 months, respectively.

In summary, QLC5508 has demonstratedLonger survival period and controllable, tolerable safetyQLC5508 2.0 mg/kg Q2W dosing regimen is currently undergoing a Phase III clinical trial.

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