QLC5508 (MHB088C), a Novel B7-H3-Targeting Antibody-Drug Conjugate, Demonstrates Promising Efficacy and Manageable Safety in Heavily Pretreated Extensive-Stage Small Cell Lung Cancer: Updated Phase 1 Data Presented at WCLC 2025

Sep 08, 2025 17:02 CST Updated 17:02

Qilu Pharmaceutical

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By combining highly potent cytotoxic drugs with highly selective monoclonal antibodies, antibody-drug conjugates (ADC) has become one of the most promising and rapidly developing novel anti-cancer therapies. From September 6 to 9, the World Conference on Lung Cancer 2025 (WCLC2025) was held in Barcelona, Spain. Qilu Pharmaceutical Co., Ltd. presented the new B7-H3 ADC drug QLC5508 for the treatment of previously treated extensive-stage small cell lung cancer (ES-SCLC) at the conference.ⅠUpdated data from the clinical study. The results of this study are presented asLatest Breakthrough Summary (Late-Breaking Abstract (LBA) was accepted by the conference as an oral presentation, delivered by Professor Zhou Caicun from East Hospital affiliated with Tongji University, who is also the 2025~2027 term President of the International Association for the Study of Lung Cancer (IASLC), during the session "Novel ADCs in SCLC (Small Cell Lung Cancer)."Special SessionHeavyweight Release.

Professor Zhou Caicun's On-site Report

As one of the most influential events in the global oncology community, the World Conference on Lung Cancer has always been an important academic exchange platform for cutting-edge advancements in lung cancer and other thoracic malignancies.Every year, authoritative experts and scholars from all over the world gather here to discuss the latest research findings, share clinical practical experiences, and contemplate future development directions.

0A06.02. Safety and Efficacy of QLC5508 in Previously Treated Patients with Small Cell Lung Cancer: Updated Data from a Phase 1 Study

QLC5508Treatment of Previously Treated Extensive-Stage Small Cell Lung Cancer (ES-SCLC）IUpdated Data on Efficacy and Safety from Phase Clinical Studies

Report Section:0A06. Novel ADCs in SCLC

Report Format:Oral

Report Time:September 7, 2025, 04:57 PM-05:07PM

QLC5508 (MHB088C) is a product based onInnovative B7-H3-Targeted Antibody-Drug Conjugate Developed on the SuperTopoi™ ADC Platform。This YearIn May, Qilu Pharmaceutical acquired the Greater China rights to the product from Minghui Pharmaceutical Ltd. for 1.345 billion yuan.ⅠPhase Clinical TrialPreliminary data for ES-SCLC patients were orally presented at the 2025 American Society of Clinical Oncology (ASCO) meeting. The data showed good safety and tolerability in previously treated ES-SCLC patients, along with encouraging anti-tumor activity.As an outstanding representative of innovation in China's pharmaceutical industry, Qilu Pharmaceutical has actively participated in the international academic stage with the latest updated data, fully demonstrating China's rise in the field of global innovative drug research and development.

New Data Show Clinical Potential

The Development of Combination Drug Therapy is Worth Looking Forward To

B7-H3 (CD276) is a member of the B7 family, playing an immunomodulatory role in T-cell responses and is considered a potential new target for cancer immunotherapy.Numerous studies have confirmed,B7-H3 is lowly expressed in most normal tissues but widely expressed in various human malignant tumors, such as prostate cancer, pancreatic cancer, breast cancer, colorectal cancer, lung cancer, and ovarian cancer. Moreover, B7-H3 is also associated with tumor cell proliferation, metastasis, treatment resistance, and poor patient prognosis.

QLC5508By specifically binding to the surface of tumor cellsB7-H3, delivering a potent topoisomerase inhibitor payload precisely into the tumor to achieve highly effective anti-tumor activity. Data shows that its payloadSuperTopoi^TMThe efficacy is higher than that of camptothecin (Dxd) 5 to 10 times higher.

This timeWCLC2025 Conference, ReleasedⅠPhase Clinical TrialLatest Data on Survival and Safety in ES-SCLC Patients.As ofJune 13, 2025In1.6 mg/kg Q2W, 2.0 mg/kg Q2W, and 2.4 mg/kg Q3W three dose levelsTotal Enrollment106 patients with SCLC. Nearly half of them (47.2%) of patients had received second-line or higher treatment, and more than half of the patients (58.5%) had previously received immunotherapy. In terms of safety, the most common ≥3 grade treatment-related adverse events (TRAEs) were decreased neutrophil count (17.0%) and decreased white blood cell count (10.4%).。

In terms of efficacy,QLC5508 in three dose groups: 1.6 mg/kg Q2W, 2.0 mg/kg Q2W, and 2.4 mg/kg Q3WConfirmObjective Response Rate（ORR) were 21.4%, 42.2%, and 43.3%, respectively, with disease control rates (DCR) of 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. The dose of 2.0 mg/kg Q2W will be recommended for further clinical trials.

Currently,QLC5508 is currently undergoing trials involving multiple types of tumors, including lung cancer, prostate cancer, and esophageal cancer.Ⅱ、ⅢPhase clinical trial. It is worth noting that, inIn addition to B7-H3, the B7 family includes multiple immune checkpoint molecules such as B7-H1 (PD-L1), B7-1 (CD80), and B7-2 (CD86). Particularly, numerous PD-1/L1 products targeting B7-H1 (PD-L1) have been approved and marketed.Tumor Immunotherapy (IO）Field Global Spotlight"Blockbuster" combination therapies among numerous drugs are also highly anticipated in the industry.

Currently, tumor immunotherapy has ushered inIn the 2.0 new era, QLC5508 is expected to collaborate with Qilu Pharmaceutical's self-developed and already marketed innovative drug PD-1/CTLA-4 bispecific combination antibody, Qibean.^®（QL1706, Aipalolituo Weirui Monoclonal Antibody: Building a New Paradigm for Tumor Treatment with IO2.0+ADC.

Global Innovation Benefits Patients

Let pharmaceutical innovation be more humane

Focusing on unmet clinical needs,The academic milestones achieved by QLC5508 in global development, as well as the innovative potential demonstrated in niche markets and combination therapies, are merely a microcosm of Qilu Pharmaceutical's commitment to "expressing love through science." Whether through external licensing or internal independent research and development, Qilu Pharmaceutical...In"Innovations with warmth" as the core concept, deeply integrating technological innovation with humanistic care, has led to a distinctive path of high-quality development. This path not only embodies a profound respect for life and health but also demonstrates the responsibility and commitment of China's pharmaceutical enterprises.

Technological innovation has never been a castle in the air, but rather a result of strategic determination and resource accumulation over time. The R&D investment intensity of Qilu Pharmaceutical has increased from a decade ago.From 5%~8% to 10%~12%, the seemingly small percentage increase actually represents a shift in corporate strategic focus. The R&D investment of 4.38 billion yuan in 2024 and the commitment to accumulate over 20 billion yuan in investments during the "14th Five-Year Plan" period outline the company's steadfast stance in supporting innovation with substantial resources, demonstrating its determination to innovate.

This strategic resolve is further reflected in the talent system. Qilu Pharmaceutical5200YuThe proportion of PhDs in the dedicated R&D team reaches34.4%. This scientific research team, which has an international perspective, collaborates with top Chinese universities such as Tsinghua University and Zhejiang University, as well as international authoritative institutions like Memorial Sloan Kettering Cancer Center in New York and the National Cancer Institute (NCI) in the United States. By building a collaborative innovation ecosystem that integrates industry, academia, research, and application, Qilu Pharmaceutical is breaking through key technical bottlenecks and forging ahead in the deep waters of innovative drug development.

In the field of cancer treatment, Qilu Pharmaceutical has formed a pipeline layout for innovative drugs with multiple targets and mechanisms.Iruak Tablets (Qixinkex) Approved for Marketing in June 2023^®) As the only drug in its class with all clinical research data completed in ChinaALK Inhibitor, After a Decade of Development, Achieves a Median Progression-Free Survival of 45.9 Months. Its Efficacy and Safety Data Are More Aligned with the Clinical Characteristics of Patients in China, Benefiting Over Ten Thousand Patients in Its First Year on the Market.

More milestone-like isEpaprelimab Injection Approved in September 2024. As the world's first PD-1/CTLA-4 bifunctional combination antibody, this drug is based on Qilu Pharmaceutical's global...FirstCreated byMabPair^®Technical platform to achieve the same cell line covering two targets, expressing two antibodies, andPD-1 and CTLA-4 monoclonal antibodies combined in a 2:1 golden ratio offer a dual immunotherapy with higher safety, lower toxicity, better tolerance, and enhanced therapeutic effects, providing significant survival benefits for cervical cancer patients.

In the development of biologics, Qilu Pharmaceutical has built a comprehensive system coveringA full-chain platform for cutting-edge technologies such as ADCs, bispecific/multispecific antibodies. For instance, QLS5132 Injection, as the first ADC drug targeting CLDN6 in China, fills the gap in innovative drug development for this target in China, breaking the technological lead of foreign countries in this frontier field and opening a new path for targeted cancer therapy in China; QLS4131 Injection, as a BCMA/GPRC5D/CD3 trispecific antibody drug, has demonstrated breakthrough efficacy in the treatment of multiple myeloma. At the end of April, its newly added indication for systemic lupus erythematosus was approved for clinical trials, further expanding its range of applications.

As a Chinese pharmaceutical company committed to advancing towards innovative internationalization, Qilu Pharmaceutical leverages the collaborative network of its six major R&D centers in both China and the U.S. to comprehensively promote the global development of innovative drugs.Currently, Qilu Pharmaceutical Co., Ltd. hasMore than 80 innovative drug projects are under development, with 20 in clinical stages. Among the six projects approved for clinical trials this year, four have achieved dual filings in China and the U.S. Focusing on unmet clinical needs, Qilu Pharmaceutical is accelerating its layout in major disease areas, providing breakthrough medication solutions for urgent clinical needs and addressing significant life-and-health challenges faced by patients with heavy burdens.

Source: Qilu Pharmaceutical

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