Citius Pharmaceuticals’ Lymphir is a reformulated version of denileukin diftitox—an FDA-approved cancer therapy—and the only treatment for cutaneous T cell lymphoma that targets the IL-2 receptor located on malignant T cells and Tregs.
The FDA on Thursday signed off on Citius Pharmaceuticals’ Lymphir (denileukin diftitox-cxdl) for the treatment of patients with relapsed or refractory cutaneous T cell lymphoma, who have undergone at least one prior line of systemic therapy.
Lymphir is Citius’ first FDA-approved product and currently the only treatment for cutaneous T cell lymphoma (CTCL) that targets the IL-2 receptor located on malignant T cells and Tregs. The New Jersey-based company expects to launch Lymphir “within the next five months,” CEO Leonard Mazur said in a statement.
“Lymphir offers new hope for patients suffering from cutaneous T cell lymphoma, a rare and chronic cancer characterized by debilitating skin lesions and severe itching,” Mazur said, calling the approval of Lymphir a “significant milestone” for patients suffering from CTCL. The drug will not only give patients and their doctors a new effective treatment option but will also expand the current CTCL market, which is currently around $300 million to $400 million in value, according to Mazur.
Lymphir is a reformulation of the FDA-approved cancer treatment denileukin diftitox, which combines the IL-2 cytokine and the diphtheria toxin. The drug works by binding to IL-2 receptors on malignant T cells and immunosuppressive regulatory T cells and releasing its toxin payload, triggering the death of its target cells.
Citius’ reformulation of denileukin diftitox retains its original amino acid sequence but has an improved purity and bioactivity, according to the biotech’s website.
The company previously tried to secure approval for Lymphir but was rejected in July 2023. In its Complete Response Letter, the FDA outlined the need for “enhanced product resting requirements,” according to Citius’ third-quarter business report that year. In September 2023, Citius received regulatory guidance from the FDA, which ultimately resulted in its BLA resubmission in February 2024.
According to Citius, its resubmitted data package included findings from the Phase III Study 302 trial which enrolled patients who had undergone a median of four prior anticancer therapies. Objective response rate, the study’s primary endpoint, was 36.2% following treatment with Lymphir, with 8.7% reaching complete response.
Lymphir’s onset of response was rapid, with effects arising after a median of 1.41 months, with most responders experiencing results after one or two cycles of Lymphir treatment. More than half of patients had median duration of response of at least six months.
Lymphir carries a boxed warning for capillary leak syndrome (CLS), some cases of which can be life-threatening or fatal. In the drug’s clinical trials, CLS manifested as hypotension, edema and serum albumin levels lower than 3 g/dL.
