Fennec Pharmaceuticals Announces Oral Presentation of Detailed Results from Investigator-Initiated Phase 2 STS-J01 Clinical Study of Pedmark® in Japan at SIOP 2026

~ Primary Endpoint Met: American Speech-Language-Hearing Association (ASHA)-Defined Hearing Loss Occurred in 24.0% of Patients Versus the Prespecified Historical Benchmark of 56.4% (P=0.001) ~

~ 84% of Patients Had Grade 0 Hearing Loss by Brock Criteria; No Grade 3 or Grade 4 Hearing Loss Was Observed ~

~ Objective Responses Observed in 23 of 24 Evaluable Patients (95.8%); Prospective Pharmacokinetic Analyses Provide New Mechanistic Insight Supporting the Six-Hour PEDMARK ® Administration Interval for Pediatric & Adolescent and Young Adult (AYA) Patients ~

~ Building Upon the Pivotal Children’s Oncology Group (COG) Protocol ACCL0431 & SIOPEL 6 Studies, STS-J01 Represents Third Study to Demonstrate that PEDMARK ® S howed No Interference with Cisplatin Antitumor Activity ~

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RESEARCH TRIANGLE PARK, N.C., Sept. 17, 2026 (GLOBE NEWSWIRE) — Fennec Pharmaceuticals Inc. (NASDAQ:FENC; TSX: FRX), a specialty pharmaceutical company, today announced the oral presentation of detailed results from the investigator-initiated Phase 2 STS-J01 clinical trial evaluating PEDMARK ® (sodium thiosulfate injection) for the reduction of cisplatin-induced ototoxicity in pediatric and adolescent and young adult (AYA) patients with non-metastatic solid tumors in Japan. The data will be presented today during the 58 th Annual International Society of Pediatric Oncology (SIOP) Annual Meeting in San Antonio, TX.

PEDMARK ® is the first and only U.S. Food and Drug Administration (FDA) approved therapy indicated to reduce the risk of ototoxicity associated with cisplatin treatment in pediatric patients 1 month of age and older with localized, non-metastatic, solid tumors, and is also recognized by the National Comprehensive Cancer Network with a 2A endorsement for use in AYA patients.

The study enrolled 33 patients across 11 institutions in Japan, including 27 patients in the primary cohort and six in exploratory cohorts. Key study findings include:

“The clinical and pharmacologic findings of STS-J01 are compelling. We observed a significant reduction in hearing loss, with no Grade 3 or Grade 4 hearing loss by Brock criteria, alongside a 95.8% objective response rate in evaluable patients. The prospective pharmacokinetic analyses further provide important mechanistic insight into why the six-hour interval matters, supporting a model in which PEDMARK ® acts on residual circulating and exchangeable platinum after cisplatin has had time to distribute and initiate its antitumor activity. Together, these findings add an important independent body of evidence supporting the clinical rationale for delayed PEDMARK ® administration,” said Pierre S. Sayad, PhD, M.S., chief medical officer of Fennec Pharmaceuticals.