Eton Pharmaceuticals Expands Rare Disease Portfolio Through Agreement for U.S. Commercialization Rights to IMPAVIDO® (miltefosine)

Eton Pharmaceuticals Secures U.S. Commercialization Rights for IMPAVIDO®

Eton Pharmaceuticals has entered into a supply and distribution agreement with an affiliate of Knight Therapeutics, Inc. to acquire exclusive U.S. commercialization rights for IMPAVIDO® (miltefosine). IMPAVIDO® is the first and only FDA-approved oral orphan drug for treating visceral, cutaneous, and mucosal leishmaniasis caused by specific Leishmania species in adults and adolescents over 12 years and weighing more than 30 kg. This strategic move, effective September 26, 2026, expands Eton's rare disease portfolio and reinforces its focus on specialized patient populations.

• IMPAVIDO® (miltefosine) is highlighted as the first and only FDA-approved oral therapy for visceral, cutaneous, and mucosal leishmaniasis caused by specific Leishmania species. It is indicated for adults and pediatric patients aged 12 years and older, weighing at least 30 kg, addressing a critical need for this rare, potentially life-threatening parasitic disease.
• The agreement grants Eton Pharmaceuticals exclusive U.S. commercialization rights to IMPAVIDO® from an affiliate of Knight Therapeutics, Inc. This supply and distribution agreement is set to take effect on September 26, 2026, marking another product launch for Eton in the upcoming year.
• This acquisition significantly expands Eton's growing portfolio of orphan therapies, aligning with the company's core strategy of developing and commercializing treatments for rare diseases. It strengthens Eton's commercial model and patient support capabilities for highly specialized patient populations across multiple therapeutic areas.

The Critical Need for Effective Leishmaniasis Treatments

Current leishmaniasis treatments face significant challenges across all disease forms, with traditional therapies hampered by high toxicity, substantial costs, and emerging drug resistance. The lack of well-tolerated, effective, and affordable treatment options particularly affects the world's poorest populations, who bear a disproportionate economic burden from this neglected tropical disease.

• Drug resistance and treatment failures are increasing to alarming levels globally, with high rates of treatment failure observed during recent outbreaks, while current diagnostic tools cannot differentiate between resistant and sensitive parasite phenotypes

• Economic barriers create catastrophic expenditure (>10% of monthly income) for 42.6% of affected families, with direct treatment costs averaging USD 117.36 and indirect costs from lost workdays reaching USD 9,936.58 per treatment cycle

• Toxicity and safety concerns limit the use of traditional drugs, with photosensitizing compounds for photodynamic therapy exhibiting cytotoxicity and allergic reactions, while conventional amphotericin B formulations cause significant nephrotoxicity

• Treatment complexity and variability complicate management decisions, as visceral leishmaniasis in East Africa requires higher liposomal amphotericin doses compared to India, and cutaneous leishmaniasis guidelines vary significantly between regions

• Drug availability and quality issues persist globally, with interrupted supply chains, poor-quality medications, and lack of standardized treatment protocols particularly affecting endemic regions

• Limited therapeutic options exist for immunocompromised patients, including organ transplant recipients and HIV co-infected individuals, where duration of therapy, curative criteria, and need for secondary prophylaxis remain unclear

• Species-specific treatment challenges arise from the diversity of Leishmania strains involved in infections, requiring tailored approaches based on parasite species, disease extent, patient profile, and previous treatment history

Eton's Strategic Expansion into Rare Leishmaniasis Populations

Recent research has identified several critical unmet medical needs and vulnerable populations requiring targeted interventions for leishmaniasis management. The growing geographical overlap of HIV-1 and Leishmania infections represents an emerging global challenge, while outdated treatment regimens and diagnostic gaps continue to hinder optimal patient care.

Key Populations Being Targeted:

• People living with HIV (PWH) - identified as a critical population due to high co-infection rates and increased morbidity and mortality, with prevalence of L. infantum seropositivity reaching 16.27% in Bahia, Brazil cohorts and visceral leishmaniasis serving as an opportunistic infection in HIV-1 infected individuals

• Immunocompromised patients - representing 30% of cases in UK studies, with patients having mucosal or visceral leishmaniasis more frequently immunosuppressed than those with cutaneous forms, leading to atypical clinical manifestations and delayed diagnosis

• Pediatric populations - particularly vulnerable with children under 14 years accounting for 53% of cutaneous leishmaniasis cases in Palestine studies, and children under 10 years representing the largest proportion (34.9%) of confirmed cases in Iran

• Military personnel - exposed to endemic regions and new biospheres during deployment, facing threats from Leishmania pathogens with poor recognition upon return to non-endemic countries leading to treatment delays

• Rural and marginalized communities - with 61% of cutaneous leishmaniasis cases in Palestine residing in villages compared to urban areas, often associated with malnutrition, poor health services, and limited access to prophylactic control measures

Critical Unmet Medical Needs:

• Treatment limitations - current drug regimens are outdated with significant cytotoxicity and resistance issues, requiring urgent development of novel, efficacious and less toxic therapeutic alternatives with improved accessibility

• Diagnostic challenges - poor recognition in non-endemic settings, reduced sensitivity of rapid diagnostic tests in children under 3 years and HIV co-infected individuals, and chronic underdiagnosis in endemic regions

• Vaccine development - prophylactic vaccine remains an unfulfilled goal despite natural infection eliciting robust immunity, with multiple candidates showing promising animal data but requiring translation into affordable and accessible control tools

• Co-infection management - HIV-Leishmania co-infection increases mortality risk (adjusted odds ratio 10) with significant reduction in CD4 counts and intensified immune activation requiring specialized management protocols

• Pathogenesis understanding - leishmanial pathogenesis remains poorly established, limiting development of targeted therapeutic interventions and contributing to diagnostic delays and treatment failures

IMPAVIDO®'s Place in Leishmaniasis Treatment Guidelines

Current treatment guidelines for leishmaniasis vary significantly by geographic region, disease form, and causative species. The therapeutic landscape has evolved from traditional pentavalent antimonials to include newer agents and combination regimens, though challenges remain with drug resistance, toxicity, and limited treatment options.

Visceral Leishmaniasis Treatment Guidelines:

• Indian Subcontinent: Single-dose liposomal amphotericin B (5 mg/kg) followed by 7-14 days of miltefosine is the recommended treatment of choice, showing 98% cure rates and replacing pentavalent antimonials due to widespread resistance in Bihar, India

• East Africa: 17-day combination therapy of pentavalent antimonials with paromomycin remains the standard treatment, as African Leishmania donovani strains show less susceptibility to liposomal amphotericin B compared to Indian strains

• Mediterranean and South America: Liposomal amphotericin B at total doses of 18-21 mg/kg is the recommended regimen for these regions

• HIV coinfection: Liposomal amphotericin B is the treatment of choice for HIV-VL coinfection, with secondary prophylaxis recommended for immunosuppressed patients

Cutaneous Leishmaniasis Treatment Guidelines:

• Localized disease: Topical therapies including cryotherapy, thermotherapy, and intralesional antimonial injections are preferred for cosmetically insignificant lesions that are often self-limited

• Systemic treatment: Pentavalent antimonials remain first-line therapy for severe forms, larger lesions, or cosmetically significant disease, though problems exist with toxicity, compliance, and availability

• Species-directed therapy: European guidelines favor species-specific treatment approaches, with paromomycin ointments effective for L. major, L. tropica, L. mexicana, and L. panamensis, while intramuscular pentamidine is required for L. guyanensis

• Oral alternatives: Miltefosine is available as the only oral option but faces limitations including resistance, high cost, and restricted availability in endemic countries

Mucosal Leishmaniasis Treatment Guidelines:

• First-line therapy: Pentavalent antimonial derivatives remain strongly recommended despite treatment recommendations being based on low or very low-quality evidence

• Alternative agents: Miltefosine shows cure rates similar to antimony in direct meta-analysis, while other options include pentamidine, amphotericin B formulations (liposomal, lipid complex, colloidal dispersion), and combination regimens with pentoxifylline

• Combination approaches: Antimony combined with pentoxifylline may provide enhanced efficacy compared to antimony monotherapy for this challenging form of leishmaniasis

Eton's Strategic Bet: Oral Leishmaniasis Therapy in the U.S.

Eton Pharmaceuticals' recent agreement to acquire U.S. commercialization rights for IMPAVIDO (miltefosine) represents a calculated and impactful move within the specialized pharmaceutical sector. This strategic expansion reinforces Eton's commitment to rare disease and orphan drug markets, particularly for conditions with significant unmet needs. Leishmaniasis, a group of neglected tropical diseases, continues to pose a substantial global health burden, characterized by challenging treatment paradigms.

Historically, therapies for leishmaniasis have been limited by their parenteral administration, high cost, and considerable toxicity, with widespread drug resistance to mainstay antimonials further complicating management. Miltefosine, as the first and only FDA-approved oral therapy for specific forms of leishmaniasis, offers a compelling alternative. Its oral route significantly enhances patient convenience and can improve treatment adherence, especially beneficial for pediatric patients and those in remote areas. Moreover, its demonstrated efficacy against antimonial-resistant strains addresses a critical clinical challenge.

However, the commercialization of miltefosine in the U.S. is not without its considerations. The drug is known for its adverse event profile, with common gastrointestinal side effects that can impact tolerability and lead to treatment modifications or discontinuation. More severe, though less frequent, adverse events such as acute renal failure and male genitourinary issues have also been reported, underscoring the need for close clinical and laboratory monitoring. Furthermore, miltefosine carries teratogenic potential, which necessitates strict precautions and limits its use in certain patient populations, particularly women of childbearing age. There are also ongoing concerns about the potential for drug resistance to emerge with prolonged or inappropriate use, and some studies have noted a decline in efficacy for longer treatment durations.

For Eton, navigating these complexities will be key. While miltefosine offers a vital oral option, strategic efforts will be required to manage patient expectations regarding side effects, implement robust risk mitigation programs, and potentially explore future combination therapy strategies to preserve efficacy and combat resistance. This acquisition positions Eton to make a meaningful impact on a neglected disease, but success will hinge on comprehensive patient support and vigilant pharmacovigilance.