Fennec Pharmaceuticals Reports Second Quarter 2025 Financial Results And Provides Business Update

~ Achieved Second Quarter 2025 Total Net Revenues of $9.7 Million ~

~ Double Digit New Accounts in the Second Quarter of 2025, Including Notable Quarter-Over-Quarter Growth in Both Large Community Practices and Academic Centers, Supported by Targeted Sales Strategy and Enhanced Patient Support Services forPEDMARK®~

~ Successful Initial Uptake of PEDMARQSI®in the United Kingdom and Germany with Additional EU Launches Planned ~

~ Japan Clinical Trial (STS-J01) Results Expected in the Second Half of 2025 with Evaluation of Both Registration and Partnering or Licensing Expected Thereafter ~

~ Management to Host Conference Call Today at 8:30 a.m. ET ~

RESEARCH TRIANGLE PARK, N.C., Aug. 14, 2025 (GLOBE NEWSWIRE) -- Fennec Pharmaceuticals Inc. (NASDAQ:FENC; TSX: FRX), a specialty pharmaceutical company, today reported its financial results for the second quarter ended June 30, 2025 and provided a business update.

“We are pleased to have delivered three consecutive quarters of strong performance, with second quarter revenue up 33% over the same quarter in 2024. This acceleration reflects significant progress in both large community practices and academic centers – driven by a completely overhauled go-to-market approach, increased awareness of the importance of preventing cisplatin-induced ototoxicity (CIO) and expanded patient support program offerings,” said Jeff Hackman, chief executive officer of Fennec Pharmaceuticals. “The results demonstrate the scalability of our model and the strong demand for PEDMARK®across key segments of the market. With the U.S. momentum for PEDMARK building, coupled with Norgine’s ex-U.S. PEDMARQSI®launches and results from the investigator-initiated clinical trial STS-J01 in Japan expected in the coming months, we believe the global opportunity for both patients and Fennec shareholders is significant.”

Second Quarter 2025 Conference Call InformationDate:Thursday, August 14, 2025Time:8:30 a.m. ETWebcast Link:https://edge.media-server.com/mmc/p/de4jxxzjParticipant Link:https://register-conf.media-server.com/register/BI3e750b95d06c439ea560b46f60abda54

To access the live webcast link, visitwww.fennecpharma.comand proceed to the News & Events/Event Calendar page under the Investors & Media section. Please connect to the company’s website at least 15 minutes prior to the conference call to ensure adequate time for any software download that may be required to listen to the webcast. A replay of the webcast will also be archived onwww.fennecpharma.comfor thirty days.

The selected financial data presented below is derived from our unaudited condensed consolidated financial statements, which were prepared in accordance with U.S. generally accepted accounting principles. The complete unaudited condensed consolidated financial statements for the period ended June 30, 2025, and management's discussion and analysis of financial condition and results of operations will be available via www.sec.gov and www.sedar.com. All values are presented in thousands unless otherwise noted.

Cisplatin and other platinum-based chemotherapies are widely used to treat solid tumors and have been vital in improving survival rates. Unfortunately, these life-saving treatments often result in permanent, irreversible hearing loss, also known as ototoxicity.i

Hearing loss from cisplatin treatment is not rare. Studies show that between 60-90% of patients treated with cisplatin may develop hearing loss, depending upon the dose and duration of chemotherapyii. Many of those treated with cisplatin will require lifelong hearing aids or cochlear implants, which can be helpful for some, but do not reverse the hearing loss and can be costly over time.iiiTreatment-induced hearing loss can reduce quality of survivorship as it impacts many aspects of life, such as speech and language skills, academic performance, social-emotional development, career potential and the ability to live independently.iv,vWhile audiologic monitoring is recommended to help manage ototoxicity, it is currently underutilized in certain cancer patient populations.

PEDMARK®(sodium thiosulfate injection)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. It is a unique formulation of sodium thiosulfate in single-dose, ready-to-use vials for intravenous use in pediatric patients. PEDMARK is also the first and only therapeutic agent with proven efficacy and safety data with an established dosing regimen, across two open-label, randomized Phase 3 clinical studies, the Children’s Oncology Group (COG) Protocol ACCL0431 and SIOPEL 6.

Additionally, PEDMARK is recommended for the adolescent and young adult (AYA) population by the National Comprehensive Cancer Network, or NCCN, with a 2A endorsement.

Approximately 500,000 patients in the U.S. are diagnosed annually with cancers that could be treated with a platinum-based chemotherapy. The incidence of ototoxicity depends upon the dose and duration of chemotherapy, and many of those treated will require lifelong hearing aids. Until the FDA approval of PEDMARK, there were no preventative agents for this hearing loss. Patients with hearing loss resulting from cancer treatment have a statistically significant worse quality of life compared with peers who have no hearing loss.vivii

PEDMARK has been studied by co-operative groups in two Phase 3 clinical studies of survival and reduction of ototoxicity, COG ACCL0431 and SIOPEL 6. Both studies have been completed. The COG ACCL0431 protocol enrolled childhood cancers typically treated with intensive cisplatin therapy for localized and disseminated disease, including newly diagnosed hepatoblastoma, germ cell tumor, osteosarcoma, neuroblastoma, medulloblastoma, and other solid tumors. SIOPEL 6 enrolled only hepatoblastoma patients with localized tumors.

Indications and UsagePEDMARK®(sodium thiosulfate injection) is indicated to reduce the risk of ototoxicity associated with cisplatin in pediatric patients 1 month of age and older with localized, non-metastatic solid tumors.

Limitations of UseThe safety and efficacy of PEDMARK have not been established when administered following cisplatin infusions longer than 6 hours. PEDMARK may not reduce the risk of ototoxicity when administered following longer cisplatin infusions, because irreversible ototoxicity may have already occurred.

Important Safety InformationPEDMARK is contraindicated in patients with history of a severe hypersensitivity to sodium thiosulfate or any of its components.

Hypersensitivity reactions occurred in 8% to 13% of patients in clinical trials. Monitor patients for hypersensitivity reactions. Immediately discontinue PEDMARK and institute appropriate care if a hypersensitivity reaction occurs. Administer antihistamines or glucocorticoids (if appropriate) before each subsequent administration of PEDMARK. PEDMARK may contain sodium sulfite; patients with sulfite sensitivity may have hypersensitivity reactions, including anaphylactic symptoms and life-threatening or severe asthma episodes. Sulfite sensitivity is seen more frequently in people with asthma.

PEDMARK is not indicated for use in pediatric patients less than 1 month of age due to the increased risk of hypernatremia or in pediatric patients with metastatic cancers.

Hypernatremia occurred in 12% to 26% of patients in clinical trials, including a single Grade 3 case. Hypokalemia occurred in 15% to 27% of patients in clinical trials, with Grade 3 or 4 occurring in 9% to 27% of patients. Monitor serum sodium and potassium levels at baseline and as clinically indicated. Withhold PEDMARK in patients with baseline serum sodium greater than 145 mmol/L.

Monitor for signs and symptoms of hypernatremia and hypokalemia more closely if the glomerular filtration rate (GFR) falls below 60 mL/min/1.73m2.

Administer antiemetics prior to each PEDMARK administration. Provide additional antiemetics and supportive care as appropriate.

The most common adverse reactions (≥25% with difference between arms of >5% compared to cisplatin alone) in SIOPEL 6 were vomiting, nausea, decreased hemoglobin, and hypernatremia. The most common adverse reaction (≥25% with difference between arms of >5% compared to cisplatin alone) in COG ACCL0431 was hypokalemia.

Please see full Prescribing Information for PEDMARK®at:www.PEDMARK.com.

About Fennec PharmaceuticalsFennec Pharmaceuticals Inc. is a specialty pharmaceutical company committed to sparing cancer patients further hardship by protecting their ears against the profound threat of cisplatin-induced hearing loss, or ototoxicity. Fennec is focused on the commercialization of PEDMARK®to reduce the risk of platinum-induced ototoxicity in cancer patients. PEDMARK received FDA approval in September 2022 and European Commission approval in June 2023 and United Kingdom (U.K.) approval in October 2023 under the brand name PEDMARQSI®.

In March 2024, Fennec entered into an exclusive licensing agreement under which Norgine Pharmaceuticals Ltd., a leading European specialist pharmaceutical company, will commercialize PEDMARQSI®in Europe, U.K., Australia and New Zealand. PEDMARQSI is now commercially available in the U.K. and Germany.

PEDMARK has received Orphan Drug Exclusivity in the U.S. and PEDMARQSI has received Pediatric Use Marketing Authorization in Europe which includes eight years plus two years of data and market protection. Further, Fennec has patents providing protection for PEDMARK until 2039 in both the U.S. and internationally.

For more information, please visitwww.fennecpharma.comand follow onLinkedIn.

Forward Looking StatementsExcept for historical information described in this press release, all other statements are forward-looking. Words such as “believe,” “anticipate,” “plan,” “expect,” “estimate,” “intend,” “may,” “will,” or the negative of those terms, and similar expressions, are intended to identify forward-looking statements. These forward-looking statements include statements about our business strategy, timeline and other goals, plans and prospects, including our commercialization plans respecting PEDMARK®/PEDMARQSI®, the market opportunity for and market impact of PEDMARK®/PEDMARQSI®,its potential impact on patients and anticipated benefits associated with its use, futurecommercial and regulatory milestonemilestones, Norgine’s PEDMARQSI®launches and the investigator-initiatedclinicaltrial in Japan.Forward-looking statements are subject to certain risks and uncertainties inherent in the Company’s business that could cause actual results to vary, including the risks and uncertainties that regulatory and guideline developments may change, scientific data and/or manufacturing capabilities may not be sufficient to meet regulatory standards or receipt of required regulatory clearances or approvals, clinical results may not be replicated in actual patient settings, unforeseen global instability, including political instability, or instability from an outbreak of pandemic or contagious disease, such as the novel coronavirus (COVID-19), or surrounding the duration and severity of an outbreak, protection offered by the Company’s patents and patent applications may be challenged, invalidated or circumvented by its competitors, the available market for the Company’s products will not be as large as expected, the Company’s products will not be able to penetrate one or more targeted markets, revenues will not be sufficient to fund further development and clinical studies, our ability to obtain necessary capital when needed on acceptable terms or at all, the Company may not meet its future capital requirements in different countries and municipalities, and other risks detailed from time to time in the Company’s filings with the Securities and Exchange Commission including its Annual Report on Form 10-K for the year ended December 31, 2024. Fennec disclaims any obligation to update these forward-looking statements except as required by law.

For a more detailed discussion of related risk factors, please refer to our public filings available atwww.sec.govandwww.sedar.com.

PEDMARK®PEDMARQSI®and Fennec®are registered trademarks of Fennec Pharmaceuticals Inc.

©2025 Fennec Pharmaceuticals Inc. All rights reserved. FEN-1604-v1

iRybak L. Mechanisms of Cisplatin Ototoxicity and Progress in Otoprotection. Current Opinion in Otolaryngology & Head and Neck Surgery. 2007, Vol. 15: 364-369.iiLanger T, am Zehnhoff-Dinnesen A, Radtke S, Meitert J, Zolk O. Trends Pharmacol Sci. 2013;34(8):458-469iiiLandier W. Ototoxicity and Cancer Therapy.Cancer. June 2016 Vol. 122, No.11: 1647-1658.ivClemens E, van den Heuvel-Eibrink MM, Mulder RL, et al. Recommendations for ototoxicity surveillance for childhood, adolescent, and young adult cancer survivors: a report from the International Late Effects of Childhood Cancer Guideline Harmonization Group in collaboration with the PanCare Consortium.Lancet Oncol. 2019;20(1):e29-e41v.Bass JK, Knight KR, Yock TI, Chang KW, Cipkala D, Grewal SS. Evaluation and management of hearing loss in survivors of childhood and adolescent cancers: a report from the children’s oncology group.Pediatr Blood Cancer. 2016;63(7):1152-1162.viRajput K, Edwards L, Brock P, Abiodun A, Simpkin P, Al-Malky G. Ototoxicity-induced hearing loss and quality of life in survivors of paediatric cancer. Int J Pediatr Otorhinolaryngol. 2020;138:110401. doi:10.1016/j.ijporl.2020.110401viiBass JK, Knight KR, Yock TI, Chang KW, Cipkala D, Grewal SS. Evaluation and management of hearing loss in survivors of childhood and adolescent cancers: a report from the children’s oncology group. Pediatr Blood Cancer. 2016;63(7):1152-1162.