QLC5508, a Novel B7-H3 Targeting ADC from Qilu Pharmaceutical, Demonstrates Promising Efficacy and Safety in Relapsed Extensive-Stage Small Cell Lung Cancer at 2025 WCLC

At the upcoming 2025 World Conference on Lung Cancer (WCLC) in early September）Above, Qilu Pharmaceutical B7-H3 ADC Innovative DrugQLC5508Updated Data Research Results of Phase I Clinical Trial in Patients with Extensive-Stage Small Cell Lung CancerAsLatest Breakthrough Abstract（LBA）Selected for Oral Presentation at the Conference.

International Association for the Study of Lung Cancer (IASLC)）Professor Cai-Cun Zhou, President of the 2025-2027 term of the Council and from the Oriental Hospital Affiliated to Tongji University, will deliver an oral presentation at the "New ADC Drugs for Small Cell Lung Cancer" session in Barcelona on the afternoon of September 7, local time.¹。

QLC5508 (MHB088C) is an innovative B7-H3 ADC drug introduced by Qilu Pharmaceutical from Minghui Pharmaceutical. By specifically binding to B7-H3 on the surface of tumor cells, it precisely delivers a potent topoisomerase inhibitor payload into the tumor, thereby achieving highly effective anti-tumor activity. Its payload, SuperTopoi,^TMThe efficacy is 5 to 10 times higher than Dxd.

In June this year, QLC5508 (MHB088C）Preliminary data from Phase I clinical trial in extensive-stage small cell lung cancer (ES-SCLC) patients were presented as an oral report at the 2025 American Society of Clinical Oncology (ASCO). The trial demonstrated good safety and tolerability in previously treated ES-SCLC patients, along with encouraging anti-tumor activity.²。

At the World Conference on Lung Cancer, QLC5508 presented the updated data from its study. As of June 13, 2025,A total of 106 SCLC patients were enrolled at three dose levels: 1.6 mg/kg Q2W, 2.0 mg/kg Q2W, and 2.4 mg/kg Q3W.Among them, nearly half (47.2%) of the patients had received second-line or higher treatment, and more than half (58.5%) had previously received immunotherapy. In terms of safety, the most common ≥Grade 3 treatment-related adverse events (TRAEs) were decreased neutrophil count (17.0%) and decreased white blood cell count (10.4%). In terms of efficacy, the three dosage groups were 1.6 mg/kg Q2W, 2.0 mg/kg Q2W, and 2.4 mg/kg Q3W.ConfirmThe objective response rates (ORR) were 21.4%, 42.2%, and 43.3%, respectively, the disease control rates (DCR) were 89.3%, 84.4%, and 100%, respectively, the median progression-free survival (mPFS) was 5.55 months, 5.95 months, and 5.52 months, respectively, and the median overall survival (mOS) was 11.50 months, 11.73 months, and 11.50 months, respectively. In summary, QLC5508 demonstrated superior safety, significant anti-tumor activity, and long-term survival benefits in previously treated ES-SCLC patients, with 2.0 mg/kg Q2W recommended as the dose for further study.¹。

Currently, QLC5508 is undergoing Phase II and III clinical trials for multiple types of cancer, including lung cancer, prostate cancer, and esophageal cancer.

Currently, tumor immunotherapy (IO) has entered the 2.0 new era. QLC5508 is expected to be combined with Qilu Pharmaceutical's self-developed and already marketed innovative drug PD-1/CTLA-4 bifunctional combination antibody Eparolizumab Tovorolizumab (Qibean).^®), Building a New Pattern of Tumor Treatment with IO2.0+ADC.

References:

1.https://cattendee.abstractsonline.com/meeting/21151/Session/244

2.https://www.asco.org/abstracts-presentations/ABSTRACT489388

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