Citius earns first FDA approval with Lymphir for cutaneous T-cell lymphoma

A year after facing a rejection, Citius Pharmaceuticals has secured approval from the FDA for its immunotherapy, Lymphir (denileukin diftitox-cxdl), designed to treat relapsed or refractory cutaneous T-cell lymphoma (CTCL) in patients who have previously undergone at least one systemic therapy. This milestone marks Lymphir as the first treatment explicitly targeting the interleukin-2 (IL-2) receptor on malignant T-cells and regulatory T-cells (Tregs) within this indication. Furthermore, it is the inaugural FDA-approved product for the 17-year-old New Jersey-based company, which plans to launch Lymphir within the next five months.

Lymphir is essentially a refined version of Eisai’s earlier CTCL medication, Ontak, which was available from 1999 until 2014. Eisai had to withdraw Ontak due to manufacturing challenges related to its bacterial expression system. After these issues were addressed through a more purified formulation, Eisai transferred its rights outside Asia to Dr. Reddy’s Laboratories. In 2021, Dr. Reddy’s sold Lymphir to Citius for $40 million upfront, with an additional $40 million contingent upon FDA approval.

Last summer, Citius seemed poised for FDA approval when the agency issued a complete response letter (CRL), asking the company to enhance product testing and implement “additional controls” that had previously been requested during the review process. The CRL did not identify any efficacy or safety issues.

According to Leonard Mazur, CEO of Citius, the introduction of Lymphir is expected to significantly impact the CTCL treatment landscape. Lymphir has the potential to rapidly reduce skin disease and control symptomatic itching without cumulative toxicity, which could expand the CTCL market currently estimated to be between $300 and $400 million.

Citius has not disclosed the price of Lymphir but indicated it would be in line with other systemic therapies for CTCL. CTCL, a type of non-Hodgkin lymphoma primarily affecting the skin, is the more common of the two forms of cutaneous lymphoma, developing in T-cells as opposed to B-lymphocytes. The condition often manifests as red, scaly, itchy patches on the skin and is frequently misdiagnosed as eczema. CTCL affects twice as many men as women, with most cases diagnosed after age 50. There is no curative therapy available except for allogenic stem cell transplantation, which is suitable for only a few patients.

While a minority of CTCL patients develop advanced disease characterized by tumor formation, ulceration, and involvement of lymph nodes, blood, and internal organs, most have a slow-progressing form that is treatable and generally not life-threatening. Approximately 3,000 new cases are diagnosed annually in the US, with a total of 30,000 to 40,000 people living with the disease.

Myron Czuczman, Chief Medical Officer of Citius, highlighted that Lymphir’s unique IL-2 receptor-targeted treatment stands out due to its dual action of killing tumor cells directly and depleting host Tregs to enhance the body’s immune response. This brings significant clinical benefits to a considerable percentage of relapsed and refractory CTCL patients.

The FDA approval of Lymphir is supported by a phase 3 trial demonstrating that the treatment achieved a complete or partial response in 36% of patients, with 84% experiencing a reduction in skin disease issues. The median response time was 1.4 months, with 70% of responders seeing results after one or two treatment cycles.

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