Fennec Pharmaceuticals Reports PEDMARK Data Showing Reduced Hearing Loss in Japanese Study

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1. Ownership and Share Structure Information

The information listed above was updated on the date this article was published and was compiled from information from the company and various other data providers.

Key Takeaways

• Fennec Pharmaceuticals reported positive hearing-loss results from the Phase 2 STS-J01 study of PEDMARK in Japan.
• ASHA-defined hearing loss occurred in 24% of patients, compared with a 56.4% historical benchmark.
• 76% of patients remained free of ASHA-defined hearing loss, and no Grade 3 or Grade 4 hearing loss was reported.
• Objective tumor responses were observed in 23 of 24 evaluable patients.
• Fennec is pursuing Japanese registration for PEDMARK and evaluating potential partnering or licensing opportunities.

Fennec Develops Treatments for Cancer-Related Hearing Loss

On September 17, 2026, Fennec Pharmaceuticals Inc. (FENC:NASDAQ; FRX:TSX) announced detailed results from the investigator-initiated Phase 2 STS-J01 clinical study of its PEDMARK (sodium thiosulfate injection) in Japan. The results, presented at the 58th Annual International Society of Pediatric Oncology (SIOP) Annual Meeting, evaluated PEDMARK for reducing cisplatin-induced hearing loss in pediatric and adolescent and young adult (AYA) patients with localized, non-metastatic solid tumors.

The study enrolled 33 patients across 11 institutions in Japan, including 27 patients in the primary cohort and six in exploratory cohorts. Among the 25 patients in the primary efficacy population, ASHA-defined hearing loss occurred in 24% of patients, compared with a prespecified historical benchmark of 56.4%. Additional hearing-related results included:

• 19 of 25 patients, or 76%, remained free of ASHA-defined hearing loss
• 84% of patients had Grade 0 hearing loss under Brock criteria
• No Grade 3 or Grade 4 hearing loss was observed
• Objective tumor responses were observed in 23 of 24, or 95.8%, of evaluable patients

Prospective pharmacokinetic analyses also examined the interaction between PEDMARK and cisplatin-derived platinum, providing additional data supporting the administration of PEDMARK six hours after cisplatin. According to the press release, Fennec believes that the findings add to evidence from the Phase 3 Children's Oncology Group ACCL0431 and SIOPEL 6 studies, with STS-J01 representing the third study to report that PEDMARK did not interfere with cisplatin's antitumor activity. The study's safety findings were consistent with the known tolerability profile of PEDMARK and the expected toxicities associated with cisplatin-containing chemotherapy, with no serious adverse event attributed to PEDMARK and no Grade 4 PEDMARK-related toxicity reported.

Fennec is pursuing registration of PEDMARK in Japan and is exploring partnering or licensing opportunities for the drug. PEDMARK has been approved by the U.S. Food and Drug Administration to reduce the risk of cisplatin-associated ototoxicity in pediatric patients one month of age and older with localized, non-metastatic solid tumors. The press release stated that the National Comprehensive Cancer Network also recommends PEDMARK for the adolescent and young adult population with a Category 2A endorsement.

Fennec is a specialty pharmaceutical development company that is specifically focused on treating ototoxicity in cancer patients who receive cisplatin-based chemotherapy. The company is based in North Carolina.

Pediatric Oncology Remains an Active Area of Drug Development

Pediatric oncology represents a relatively small portion of the broader cancer market, but it remains an active area of drug development. In the U.S., an estimated 9,550 children from birth through age 14 were diagnosed with cancer in 2025, with about 1,050 expected to die from the disease, according to the National Cancer Institute.

Childhood cancers include leukemia, brain and spinal cord tumors, neuroblastoma, kidney and liver cancers, bone cancers, and other solid tumors. Because many pediatric cancers are relatively rare, clinical development can involve small patient populations and specialized trial designs.

H.C. Wainwright's Raghuram Selvaraju, Ph.D., reiterated a "Buy" rating and 12-month price target of US$16 for Fennec on September 9, 2026.

The broader oncology market provides a significantly larger commercial backdrop. According to IQVIA's Global Oncology Trends 2025 report, global spending on cancer drugs reached US$252 billion in 2024 and is projected to reach US$441 billion by 2029.

Oncology also accounted for 41% of clinical trials started in 2024, with 2,162 oncology trials initiated during the year. IQVIA reported that 74% of oncology trial starts focused on rare cancers, reflecting continued development activity in patient populations with relatively limited treatment options.

Pediatric oncology is also seeing continued expansion in the number and types of available therapies. The U.S. Food and Drug Administration's pediatric oncology data show more than 60 drugs with more than 85 associated indications have been approved for pediatric cancers since the early 1950s. The agency's 2025 Oncology Center of Excellence annual report said 11 approvals covering 12 drugs and biologics resulted in 21 new indications for pediatric patients with cancer during the year. More than half of the novel oncology products approved by the FDA in 2025 were for orphan-designated indications, underscoring the role of rare cancers within oncology drug development.

Experts Eye Fennec's Growth and Corporate Development Plans

H.C. Wainwright's Raghuram Selvaraju, Ph.D., reiterated a "Buy" rating and 12-month price target of US$16 for Fennec on September 9, 2026. " We draw investors' attention to the fact that adoption continues to build across both new and existing accounts, with established prescribers demonstrating growing confidence in PEDMARK (sodium thiosulfate), contributing to deeper utilization and higher vials per account," he wrote.

On September 18, 2026, Chen Lin of What is Chen Buying? What is Chen Selling? weighed in on the company, saying, "I had a good meeting with FENC management. They are almost apologetic about selling some of the stocks they own. They explained to me that they have been with the company for over 10 years and need to pay taxes on the expiring warrants. So, they have to sell some."

Chen continued, "Other than that, the company is doing extremely well. They are hoping for 'triple digits' growth heading into next year. They are hoping for adult indication results by ASCO next year. They were cash flow positive for the first time last quarter and have US$40+ million cash on the balance sheet. Share buyback is one of the options they are considering. They are also at the stage of being acquired or acquiring some new products. I see news about corporate development coming in the next year."

Fennec Advances PEDMARK Registration and International Commercialization

According to Fennec's August 2026 investor presentation, the company is pursuing regulatory registration for PEDMARK in Japan following the STS-J01 study, while also evaluating potential partnering or licensing opportunities in the market.

In Europe, the product is being commercialized as PEDMARQSI through Norgine, which launched the product in Germany and the U.K. in 2025, and has planned additional European launches.

The company has also pointed out continued international commercialization, regulatory activity, and potential milestone payments under its European licensing agreement as areas to watch.

Ownership & Share Information¹

Fennec Pharmaceuticals Inc. has a market cap of US$382.49 million, with 35.06 million shares outstanding. The company's 52-week range is US$5.65-US$13.25.

Institutions own 54.34% of shares, while Strategic Investors own 11.39%. Management & Insiders own 2.78% of shares, and the remaining 31.49% of shares are held by Retail.

Frequently Asked Questions

Q: What is PEDMARK?
A: PEDMARK is the brand name for sodium thiosulfate injection, a drug designed to reduce the risk of cisplatin-associated hearing loss in pediatric patients receiving treatment for localized, non-metastatic solid tumors.

Q: What is cisplatin?
A: Cisplatin is a chemotherapy drug used to treat a range of cancers. One of its known side effects is ototoxicity, which can damage the inner ear and cause hearing loss.

Q: What is ototoxicity?
A: Ototoxicity refers to damage to the structures of the inner ear caused by certain medications or other substances. In patients receiving cisplatin, it can result in permanent hearing loss.

Q: What was the STS-J01 study?
A: STS-J01 was an investigator-initiated Phase 2 study in Japan evaluating PEDMARK for reducing cisplatin-induced hearing loss in pediatric, adolescent, and young adult patients with localized, non-metastatic solid tumors.

Q: How many patients participated in STS-J01?
A: The study enrolled 33 patients across 11 institutions in Japan. The primary cohort included 27 patients, while six additional patients were enrolled in exploratory cohorts.

Q: What were the main hearing-loss results?
A: Among the 25 patients in the primary efficacy population, 24% experienced ASHA-defined hearing loss, compared with a prespecified historical benchmark of 56.4%. Nineteen of the 25 patients, or 76%, remained free of ASHA-defined hearing loss.

Q: What is ASHA-defined hearing loss?
A: ASHA refers to the American Speech-Language-Hearing Association. In the STS-J01 study, ASHA criteria were used to evaluate hearing loss and determine the study's primary efficacy outcome.

Q: What were the Brock hearing-loss results?
A: Under the Brock criteria, 84% of patients had Grade 0 hearing loss. No Grade 3 or Grade 4 hearing loss was observed.

Q: Did PEDMARK appear to interfere with cisplatin's cancer-fighting activity?
A: The study's pharmacokinetic analyses provided additional data supporting the administration of PEDMARK six hours after cisplatin. According to Fennec, the STS-J01 findings add to evidence from the Phase 3 ACCL0431 and SIOPEL 6 studies indicating that PEDMARK did not interfere with cisplatin's antitumor activity.

Q: What tumor responses were observed in STS-J01?
A: Objective tumor responses were observed in 23 of 24 evaluable patients, or 95.8%. These results were reported alongside the study's hearing-related findings.

Q: Was PEDMARK well-tolerated in the study?
A: Fennec reported that safety findings were consistent with the known tolerability profile of PEDMARK and the expected toxicities associated with cisplatin-containing chemotherapy. No serious adverse event was attributed to PEDMARK, and no Grade 4 PEDMARK-related toxicity was reported.

Q: Is PEDMARK approved in the U.S.?
A: Yes. The U.S. Food and Drug Administration has approved PEDMARK to reduce the risk of cisplatin-associated ototoxicity in pediatric patients one month of age and older with localized, non-metastatic solid tumors.

Q: What is Fennec pursuing in Japan?
A: Fennec is pursuing regulatory registration of PEDMARK in Japan following the STS-J01 study results. The company is also exploring potential partnering or licensing opportunities for the product in the Japanese market.

Q: What is PEDMARQSI?
A: PEDMARQSI is the European brand name for the product. It is being commercialized in Europe through Fennec's partnership with Norgine, which launched the product in Germany and the U.K. in 2025 and has planned additional European launches.

Q: How large is the broader oncology market?
A: According to IQVIA's Global Oncology Trends 2025 report, global spending on cancer medicines reached US$252 billion in 2024 and was projected to reach US$441 billion by 2029. Oncology accounted for 41% of clinical trials initiated in 2024.

Q: Why is hearing preservation important during pediatric cancer treatment?
A: Hearing loss can be a lasting consequence of cisplatin treatment, and preserving hearing can be particularly important for children and young people because hearing affects communication, education, and development. PEDMARK is intended to reduce this treatment-related risk while allowing patients to receive cisplatin-based chemotherapy.