FDA Fast Tracks JSKN003 in Ovarian Cancer

The U.S. Food and Drug Administration (FDA) has granted fast track designation to the antibody-drug conjugate JSKN003 for the treatment of advanced or metastatic platinum-resistant recurrent epithelial ovarian cancer, primary peritoneal cancer or fallopian tube cancer (PROC), not restricted by HER2 expression.

The development was announced in a news release issued by Alphamab Oncology, the biopharmaceutical company behind the drug.

The granting of the fast track designation was based on clinical data in support of JSKN003, the news release stated. Alphamab stated that the company presented a pooled analysis of a phase 1 clinical study in Australia and a phase 1/2 clinical study in China at the 2025 annual meeting of the American Society of Clinical Oncology, and as of Feb. 28, 2025 46 patients with PROC, including 21 patients (45.7%) with HER2 IHC 0 and 18 patients (39.1%) with HER2 IHC 1+, 2+, 3+, were enrolled. Among all 46 patients, the objective response rate (ORR) was 63% and the median progression-free survival (PFS) was 7.7 months. Among patients with HER2 IHC 1+, 2+ and 3+, the ORR was 72.2% and the median PFS was 9.4 months. JSKN003 demonstrated robust PFS improvement in PROC, and the efficacy was observed across different HER2 expression subgroups.

“The maturer updated efficacy data reveal that JSKN003 provided substantial improvement in ORR, as well as benefit in PFS and [overall survival (OS)] in heavily treated [patients with] PROC, irrespective of HER2 expression,” researchers wrote in the Journal of Clinical Oncology.

According to the news release, a phase 3 clinical study of JSKN003 among patients with PROC is currently underway in China, and a phase 2 study has been approved to initiate in the United States.

More About Fast Track Designation and JSKN003

Fast track, as the FDA explains on its website, is a process that is designed to facilitate the development and expedite the review of drugs that are intended to treat serious conditions and fill an unmet medical need, with the intention of getting important new drugs to the patient earlier.

JSKN003 is an antibody-drug conjugate. This type of treatment, as defined by the National Cancer Institute on its website, is a substance made up of a monoclonal antibody chemically linked to a drug, where the monoclonal antibody binds to specific proteins or receptors found on certain types of cells, including cancer cells, and the linked drug enters these cells and kills them without harming other cells.

The drug is currently being studied in disease types including HER2-positive breast cancer, HER2-low breast cancer and HER2-positive colorectal cancer. It was previously granted orphan drug designation by the FDA for the treatment of patients with gastric cancer and gastroesophageal junction cancer in addition to PROC.

More About Ovarian Cancer and PROC

Ovarian cancer, as the news release explained, is one of the most common malignant tumors of the female reproductive system, with most patients being diagnosed at an advanced stage and the disease characterized by a high recurrence rate and significant treatment challenges, with approximately 80% of ovarian cancer cases recurring and eventually progressing to PROC.

A randomized, open-label, controlled, phase 3 study evaluating the effectiveness and safety of JSKN003 versus investigator’s choice of chemotherapy among patients with platinum-resistant, relapsed epithelial ovarian, primary peritoneal, or fallopian tube cancer is not yet recruiting, according to its listing on clinicaltrials.gov, but the trial plans to eventually enroll approximately 430 patients and has an estimated primarily completion date of Dec. 30, 2026.

References

1. “Alphamab Oncology Announces Biparatopic HER2-targeting ADC JSKN003 Was Granted Fast Track Designation by FDA for the Treatment of PROC,” news release; https://www.prnewswire.com/apac/news-releases/alphamab-oncology-announces-biparatopic-her2-targeting-adc-jskn003-was-granted-fast-track-designation-by-fda-for-the-treatment-of-proc-302596008.html
2. “Fast track,” FDA; https://www.fda.gov/patients/fast-track-breakthrough-therapy-accelerated-approval-priority-review/fast-track
3. “Antibody-drug conjugate,” National Cancer Institute; https://www.cancer.gov/publications/dictionaries/cancer-terms/def/antibody-drug-conjugate
4. “JSKN003, a biparatopic anti-HER2 antibody drug conjugate (ADC), in the treatment of platinum-resistant ovarian cancer (PROC): Updated findings from two clinical trials,” Journal of Clinical Oncology; https://ascopubs.org/doi/10.1200/JCO.2025.43.16_suppl.5557
5. “JSKN003 in Platinum-Resistant, Relapsed Epithelial Ovarian Cancer;” https://clinicaltrials.gov/study/NCT06751485#contacts-and-locations

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