Citius gains FDA approval for T-cell lymphoma drug on second attempt

The FDA has approved Citius Pharmaceuticals' new immunotherapy, Lymphir (denileukin diftitox-cxdl), for the treatment of relapsed or refractory cutaneous T-cell lymphoma (r/r CTCL) in patients who have undergone at least one prior systemic therapy. This approval follows a year after an initial application resulted in a complete response letter (CRL) that requested additional product testing and manufacturing controls. The initial CRL, issued in July 2023, did not raise any concerns about the safety or efficacy of Lymphir. Citius worked closely with the FDA to address these requests and resubmitted their application earlier this year.

Lymphir is poised to make a significant impact on the CTCL treatment landscape. According to CEO Leonard Mazur, the drug has the potential to rapidly reduce skin disease and control itching without cumulative toxicity. This could expand the CTCL treatment market, which is currently valued at approximately $300 million to $400 million.

The FDA's approval is based on data from Study 302, a pivotal late-stage trial. Results from this study showed that Lymphir achieved an overall response rate (ORR) of 36.2% in patients with relapsed or refractory Stage I-III CTCL who had received at least one prior systemic therapy. Among the responders, 8.7% achieved a complete response. The median time to response was a swift 1.4 months, with nearly 70% of responders seeing results after just one or two treatment cycles. Additionally, 84.4% of skin-evaluable patients experienced a reduction in skin tumor burden, and 12.5% saw complete clearing of their skin disease. According to an exploratory analysis, almost one-third of patients experienced a significant reduction in pruritus.

However, the drug does come with some risks. The Lymphir labeling includes a boxed warning about capillary leak syndrome, which can cause life-threatening or fatal reactions. The most common adverse reactions reported during the trial included increased transaminases, nausea, edema, lower hemoglobin levels, fatigue, and musculoskeletal pain.

Myron Czuczman, Chief Medical Officer at Citius, highlighted Lymphir's unique mechanism as a crucial factor in its effectiveness. The treatment targets IL-2 receptors to kill tumor cells directly and deplete host regulatory T-cells, thereby enhancing the body's immune response. Czuczman emphasized that this dual-action approach offers clinically meaningful benefits to a significant proportion of patients with relapsed or refractory CTCL.

Citius is gearing up to launch Lymphir within the next five months and is committed to working with healthcare providers to ensure timely access to the drug. The company has stressed its dedication to making the therapy available to those in need as quickly as possible.

Lymphir had previously received regulatory approval in Japan in 2021 for the treatment of CTCL and peripheral T-cell lymphoma. Citius acquired an exclusive license to develop and commercialize the drug, also known as E7777, in all markets except for Japan and certain regions in Asia.

The introduction of Lymphir represents a significant advancement in the treatment of CTCL, offering new hope to patients with limited options. With its ability to provide rapid symptom relief and control disease progression, Lymphir is expected to be a valuable addition to the current therapeutic arsenal. As Citius prepares for the drug's launch, the company remains committed to ensuring that healthcare providers and patients have access to this new treatment option.