Minghui Pharmaceutical and Qilu Pharmaceutical Co-Announces Updated Clinical Data of MHB088C (QLC5508) From Phase I/II Study in Heavily Pretreated mCRPC Patients at 2026 ASCO Annual Meeting

Why It Matters

The results indicate MHB088C could become a differentiated therapy for mCRPC patients who have exhausted androgen‑receptor and taxane options, addressing a sizable unmet need and strengthening Minghui's oncology pipeline.

Key Takeaways

• Phase I/II trial enrolled 59 heavily pretreated mCRPC patients.
• 12‑month rPFS rate 71.7% overall; 78.6% at 2 mg/kg.
• Grade ≥3 neutropenia, anemia, and leukopenia were most common severe AEs.
• MHB088C earned three Breakthrough Therapy Designations in Greater China.

Pulse Analysis

Metastatic castration‑resistant prostate cancer remains a therapeutic challenge, with most patients eventually progressing after androgen‑receptor pathway inhibitors and taxane chemotherapy. Emerging antibody‑drug conjugates that target novel antigens, such as B7‑H3, aim to deliver cytotoxic payloads directly to tumor cells while sparing normal tissue. Minghui’s MHB088C leverages the company’s SuperTopoi™ platform to bind B7‑H3, a protein overexpressed in aggressive prostate tumors, positioning the ADC as a potentially high‑impact option in a space where durable disease control is scarce.

The updated Phase I/II data presented at ASCO show encouraging efficacy signals. With a median radiographic progression‑free survival not yet reached and a 12‑month rPFS exceeding 70%, the trial outperforms historical benchmarks for heavily pretreated mCRPC cohorts. Notably, the 2 mg/kg every‑two‑weeks regimen achieved an even higher 12‑month rPFS of 78.6%, suggesting a dose‑response relationship. Safety outcomes were consistent with class expectations, and while grade ≥3 neutropenia, anemia, and leukopenia were observed, they were manageable within current supportive‑care frameworks.

Strategically, the program benefits from three Breakthrough Therapy Designations granted by Chinese regulators, accelerating its path toward registration. Minghui’s exclusive partnership with Qilu Pharmaceutical secures development, manufacturing, and commercialization rights across Greater China, while the company retains global rights and combination‑study opportunities. As MHB088C advances into Phase III trials for small‑cell lung and esophageal cancers, its performance in mCRPC could broaden its indication portfolio and reinforce Minghui’s position as a leading ADC developer, potentially delivering a valuable new line of therapy for patients with limited treatment alternatives.