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

HANGZHOU and SHANGHAI, China, June 1, 2026 /PRNewswire/ -- Minghui Pharmaceutical ("Minghui"), a late-stage clinical biopharmaceutical company focused on developing innovative therapies for oncology and autoimmune diseases, today announced 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) Annual Meeting.

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 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.

About Minghui Pharmaceutical

Minghui Pharmaceutical is a late-stage clinical biopharmaceutical company focused on developing innovative medicines to address unmet needs in oncology and immunology. Leveraging deep scientific expertise and proprietary technology platforms, the company has built a robust and differentiated pipeline of novel therapies.

Minghui's lead assets include an innovative topical JAK inhibitor currently under NDA review in China; a subcutaneous IGF-1R antibody in Phase III trials for thyroid eye disease; a novel PD-1/VEGF bispecific antibody in Phase 2 trials, being evaluated in combination with a TROP2 ADC; and a B7-H3 ADC in Phase 3 trial for 2L SCLC —both ADCs with strong best-in-class potential.

Forward-Looking Statements

This press release contains forward-looking statements regarding MHB088C and its clinical development plans, including potential therapeutic benefits, ongoing and planned clinical studies, regulatory expectations, and future development activities. These statements are based on the Company's current expectations and are subject to various risks and uncertainties that could cause actual results to differ materially from those expressed or implied herein, including risks related to clinical development, regulatory review, manufacturing, intellectual property protection, and other factors. The Company undertakes no obligation to update any forward-looking statements except as required by applicable laws and regulations.

SOURCE Minghui Pharmaceutical