Addressing a Critical Unmet Need: Cisplatin-Induced Ototoxicity
Cisplatin, a cornerstone platinum-based chemotherapy agent, is undeniably effective in treating a wide spectrum of solid tumors across all age groups. Its powerful cytotoxic mechanism, involving the formation of DNA adducts that interfere with replication and transcription, makes it indispensable in oncology. However, its therapeutic benefits often come at a significant cost: ototoxicity, a severe and often permanent side effect that manifests as hearing loss. Published studies paint a stark picture, estimating that between 60% and 90% of patients receiving cisplatin may develop some degree of hearing loss. This wide range is influenced by various factors including the cumulative dose of cisplatin, the duration of treatment, concurrent radiation therapy, individual genetic predispositions, and age.
For young cancer patients, the implications of cisplatin-induced hearing loss extend far beyond the immediate physiological impact. In children and adolescents, whose auditory systems are still developing and who are in critical stages of language acquisition and cognitive development, such hearing impairment can have profound and lasting consequences. These include significant delays in speech and language development, leading to communication difficulties and potential social isolation. Furthermore, hearing loss can adversely affect academic performance, hindering learning and concentration in educational settings. Social-emotional development can also be impacted, as children may struggle with peer interactions and self-esteem issues due to their inability to fully participate in auditory environments. In severe cases, the resulting hearing loss may necessitate lifelong reliance on hearing aids or even cochlear implants, adding a substantial burden to their quality of life post-treatment. This underscores the urgent medical need for effective otoprotective strategies that do not compromise the antitumor efficacy of cisplatin.
Detailed Findings from the STS-J01 Study
The STS-J01 study enrolled a total of 33 patients across 11 leading institutions throughout Japan. This cohort was divided into a primary efficacy group of 27 patients and an exploratory group of six patients. Among the 25 patients ultimately included in the primary efficacy population for assessment, a remarkable 24% (6 out of 25 patients) developed hearing loss, as meticulously defined by the stringent American Speech-Language-Hearing Association (ASHA) criteria. This figure stands in stark and statistically significant contrast (P=0.001) to a prespecified historical benchmark, which indicated a much higher rate of 56.4% hearing loss in similar patient populations receiving cisplatin without otoprotection.
Delving deeper into the auditory outcomes, the study revealed that an impressive 19 of the 25 patients, accounting for 76%, remained entirely free of ASHA-defined hearing loss. Furthermore, when assessed using the widely recognized Brock grading criteria, an even more encouraging 84% of patients exhibited Grade 0 hearing loss, signifying no audiometric changes. Crucially, researchers observed no instances of severe Grade 3 or Grade 4 hearing loss, which represent the most debilitating levels of auditory impairment, within the study population.
It is important to note the design of STS-J01: it was an open-label, single-arm trial. This means that the hearing outcomes observed in the PEDMARK-treated group were rigorously compared against a robust, prespecified historical benchmark derived from similar patient cohorts, rather than against a concurrently randomized control group. While randomized controlled trials are generally considered the gold standard, ethical considerations often preclude withholding a potentially life-saving or quality-of-life-improving intervention from a control group, particularly in vulnerable pediatric oncology populations. Patients participating in the study received PEDMARK intravenously, administered consistently six hours following each cisplatin infusion, with dosing meticulously adjusted according to individual patient body weight to ensure optimal therapeutic levels.
The Crucial Role of Administration Timing: Six-Hour Interval Confirmed
A pivotal aspect of the STS-J01 findings lies in the robust support it provides for the optimal timing of PEDMARK administration. The study’s prospective pharmacokinetic analyses offered invaluable additional mechanistic evidence that strongly endorses the critical six-hour interval between the completion of cisplatin infusion and the subsequent administration of PEDMARK. This specific timing has been a central tenet of the treatment approach for PEDMARK and is now further validated.
Dr. Pierre S. Sayad, PhD, M.S., Chief Medical Officer at Fennec Pharmaceuticals, elaborated on this critical insight. He explained that these pharmacokinetic analyses provide a deeper understanding of why the six-hour interval is so crucial. The underlying model suggests that PEDMARK acts by chelating and detoxifying residual circulating and exchangeable platinum that remains in the body after cisplatin has had sufficient time to distribute effectively throughout the patient’s system and initiate its vital antitumor activity within cancer cells. This delayed administration strategy is designed to maximize the otoprotective effect without interfering with cisplatin’s primary function of destroying cancer cells.
These new findings from Japan significantly augment the growing body of evidence that consistently supports PEDMARK as an effective agent for the prevention of cisplatin-related hearing loss. Data presented earlier in the year, derived from other studies, also meticulously examined the interplay between hearing protection and antitumor outcomes with sodium thiosulfate, with the precise six-hour interval between cisplatin and PEDMARK administration playing an indispensable role in ensuring both safety and efficacy.
Preserving Antitumor Activity While Enhancing Safety
A paramount concern in any supportive care intervention during cancer treatment is ensuring that the protective agent does not compromise the primary antitumor efficacy of the chemotherapy itself. The STS-J01 study delivered highly encouraging results on this front. Objective tumor responses were reported in an impressive 23 out of 24 evaluable patients, translating to a remarkable 95.8% objective response rate. This high response rate is a critical indicator that the delayed administration of PEDMARK did not, in any discernible way, diminish cisplatin’s ability to combat the solid tumors.
Furthermore, the safety profile observed in the STS-J01 study was entirely consistent with PEDMARK’s known tolerability profile, which has been established in previous extensive clinical trials. The reported adverse events were largely aligned with the expected toxicities commonly associated with cisplatin-containing chemotherapy regimens, which include myelosuppression, nausea, vomiting, and nephrotoxicity, among others. Crucially, investigators reported no serious adverse events that were directly attributed to PEDMARK. Additionally, there were no instances of Grade 4 PEDMARK-related toxicity, indicating a favorable safety margin for the otoprotective agent. This consistent safety and efficacy data reinforce the growing confidence in PEDMARK as a valuable addition to the pediatric oncology armamentarium.
Fennec Pharmaceuticals highlighted that the STS-J01 results contribute significantly to the cumulative findings from two other landmark studies: the Children’s Oncology Group Protocol ACCL0431 and the SIOPEL 6 trials. Together, these three studies provide robust, independent evidence that the strategy of delayed PEDMARK administration effectively mitigates ototoxicity without interfering with the crucial antitumor activity of cisplatin. This tripartite validation is a powerful testament to the drug’s potential. These results further add to previously reported research meticulously examining PEDMARK for the prevention of cisplatin-related hearing loss, including detailed findings on the optimal treatment timing and the critical balance of achieving hearing protection without compromising cisplatin’s potent antitumor capabilities.
Global Regulatory Landscape and Future Expansion
The journey of PEDMARK from clinical trials to patient access has been marked by significant regulatory milestones. In the United States, PEDMARK (sodium thiosulfate injection) received approval from the U.S. Food and Drug Administration (FDA) in September 2022. This approval specifically allows for its use to reduce the risk of ototoxicity associated with cisplatin treatment in pediatric patients aged one month and older who have localized, non-metastatic solid tumors. Beyond this age-specific approval, PEDMARK has also garnered recognition from the National Comprehensive Cancer Network (NCCN), receiving a Category 2A recommendation for its use in adolescent and young adult patients, further broadening its potential impact.
Fennec Pharmaceuticals’ commitment to global patient access is evident in its continued efforts to expand PEDMARK’s availability. Following its FDA approval, the European Commission granted approval for PEDMARK in June 2023, under the brand name PEDMARQSI®. This was swiftly followed by approval in the United Kingdom in October 2023, also under the PEDMARQSI® brand. To facilitate wider distribution and commercialization in key international markets, Fennec entered into an exclusive licensing agreement in March 2024 with Norgine Pharmaceuticals Ltd. Under this agreement, Norgine Pharmaceuticals Ltd. is responsible for commercializing PEDMARQSI® across Europe, the U.K., Australia, and New Zealand. As a result of these strategic partnerships, PEDMARQSI is now commercially available in multiple countries, offering a critical otoprotective option to a growing number of young cancer patients worldwide.
Looking ahead, Fennec Pharmaceuticals is actively pursuing regulatory registration for PEDMARK in Japan. The promising results from the STS-J01 study are expected to play a crucial role in this process, providing strong clinical evidence tailored to the Japanese patient population. Concurrently, the company is exploring potential partnering or licensing opportunities within Japan, aiming to establish a robust framework for bringing PEDMARK to patients in the country. The Japanese study thus adds another valuable dataset to the ever-expanding body of research dedicated to the prevention of cisplatin-induced hearing loss, addressing what is undeniably an important long-term consideration for children and young adults undergoing life-saving cancer treatment.
Broader Impact and Implications for Young Cancer Survivors
The implications of these findings are profound, extending beyond the immediate clinical outcomes to touch upon the long-term well-being and quality of life for survivors of childhood and adolescent cancers. Historically, while medical advancements have dramatically improved survival rates for pediatric cancers, the survivors often face a myriad of late effects from their intensive treatments. Among these, hearing loss is particularly insidious, as it can be invisible yet profoundly impactful.
The consistent demonstration that PEDMARK can significantly reduce cisplatin-induced ototoxicity without compromising antitumor efficacy represents a paradigm shift in supportive care. It means that oncologists can now treat young patients with effective, life-saving cisplatin chemotherapy with greater confidence, knowing that a proven method exists to protect their hearing. This is not merely about preventing a medical side effect; it is about safeguarding a child’s ability to communicate, learn, and engage with the world around them, thereby enhancing their overall developmental trajectory and future independence.
For families, the prospect of their child enduring cancer treatment without the added burden of severe, permanent hearing loss offers immense relief. It allows them to focus more on recovery and reintegration into normal life, rather than grappling with the complex challenges of managing hearing impairment. Furthermore, the robust evidence base, now bolstered by the STS-J01 study, is likely to encourage broader adoption of PEDMARK in clinical guidelines and practice globally, further solidifying its role as a standard of care for cisplatin-treated pediatric and AYA patients. This collective effort in research and development, spearheaded by companies like Fennec Pharmaceuticals, underscores a deep commitment to not only curing cancer but also ensuring the best possible quality of life for those who overcome it.
About PEDMARK®
PEDMARK® (sodium thiosulfate injection) is FDA approved to reduce the risk of ototoxicity associated with cisplatin treatment in pediatric patients one month of age and older with localized, non-metastatic solid tumors. PEDMARK has been studied in two randomized Phase 3 clinical trials, Children’s Oncology Group Protocol ACCL0431 and SIOPEL 6, both of which demonstrated its efficacy in reducing hearing loss without compromising cancer treatment outcomes. PEDMARK is also recommended for the adolescent and young adult population by the National Comprehensive Cancer Network with a Category 2A endorsement, highlighting its recognized clinical value across a broader age range.
About Fennec Pharmaceuticals
Fennec Pharmaceuticals Inc. is a specialty pharmaceutical company steadfastly committed to addressing the critical issue of ototoxicity in cancer patients who receive cisplatin-based chemotherapy. The company’s primary focus is on the commercialization of PEDMARK® to effectively reduce the risk of platinum-induced ototoxicity in vulnerable cancer patients. PEDMARK received its foundational FDA approval in September 2022, a landmark achievement that paved the way for subsequent international recognition, including European Commission approval in June 2023 and United Kingdom approval in October 2023, under the distinct brand name PEDMARQSI®. In a strategic move to broaden global access, Fennec entered into an exclusive licensing agreement in March 2024 with Norgine Pharmaceuticals Ltd., empowering Norgine to commercialize PEDMARQSI® across key territories including Europe, the U.K., Australia, and New Zealand. As a direct result of these efforts, PEDMARQSI is now commercially available in numerous countries, extending its crucial benefits to a wider population of young cancer survivors.
