On June 1, 2026 Minghui Pharmaceutical ("Minghui"), a late-stage clinical biopharmaceutical company focused on developing innovative therapies for oncology and autoimmune diseases, reported updated clinical data from its Phase I/II study evaluating MHB088C (QLC5508) in heavily treated patients with metastatic castration-resistant prostate cancer (mCRPC). The results were presented in a poster session at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting.

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Poster title:

Safety and efficacy of QLC5508 (MHB088C) in heavily-treated patients with metastatic castration-resistant prostate cancer: Updated data from a phase 1/2 trial

Poster session:

Genitourinary Cancer—Prostate, Testicular, and Penile

The updated findings demonstrated encouraging anti-tumor activity and durable disease control in heavily pretreated mCRPC patients, including patients previously treated with androgen receptor pathway inhibitors (ARPIs) and taxane-based chemotherapy.

As of the data cutoff date of November 30, 2025, 59 patients had been enrolled in the study. The patient population represented a heavily pretreated setting:

74.6% received three or more prior lines of therapy
84.7% had prior taxanes exposure
28.8% received three or more prior lines of second-generation ARPIs
16.9% had received two or more prior lines of taxanes
Clinical Activity

MHB088C demonstrated durable anti-tumor activity.
The median rPFS was not reached (95% confidence interval [CI], 13.1-not evaluable [NE]), with a 12-month rPFS rate of 71.7% (95% CI, 52.6%-84.3%).
Among 40 patients treated at the 2.0 mg/kg Q2W dose, median rPFS was also not reached (95% CI, 13.1-NE), with a 12-month rPFS rate of 78.6% (95% CI, 50.7%-91.8%).
Safety Profile

MHB088C demonstrated a manageable safety profile, consistent with prior clinical data
Most common Grade ≥3 treatment-emergent adverse events (TEAEs):
Neutrophil count decreased (25.4%)
Anemia (23.7%)
White blood cell count decreased (20.3%)
"These updated data presented at ASCO (Free ASCO Whitepaper) further reinforce the potential of MHB088C as a differentiated therapeutic option for patients with metastatic castration-resistant prostate cancer, particularly those with limited treatment alternatives after multiple prior therapies," said Guoqing Cao, Ph.D., Chief Executive Officer of Minghui Pharmaceutical. "We are encouraged by the durable clinical benefit observed with MHB088C, including prolonged disease control in this heavily pretreated patient population, together with its manageable safety profile. These findings further strengthen our confidence in the potential of MHB088C to address significant unmet needs for patients with metastatic castration-resistant prostate cancer, and we look forward to advancing the program through its next stage of development."

About MHB088C

MHB088C is an investigational B7-H3-targeted antibody-drug conjugate (ADC) developed using Minghui’s proprietary SuperTopoi platform.

Under an exclusive licensing and collaboration agreement, Qilu Pharmaceutical holds rights for the development, manufacturing, and commercialization of MHB088C in Greater China. Minghui retains China-based combination study rights with MHB039A and global rights outside Greater China.

In Greater China, Qilu is advancing the clinical development of MHB088C across multiple indications. The program has received three Breakthrough Therapy Designations and is currently being evaluated in two Phase 3 studies in second-line small cell lung cancer (SCLC) and second-line esophageal squamous cell carcinoma (ESCC).

Minghui is advancing additional clinical development strategies for MHB088C. Ongoing studies in China include a Phase I/II trial evaluating MHB088C in combination with MHB039A, Minghui’s investigational PD-1/VEGF bispecific antibody, in patients with advanced solid tumors, including first-line SCLC expansion cohorts.

(Press release, Minghui Pharmaceutical, JUN 1, 2026, View Source [SID1234666337])