Armed with Robust Data, Citius Will Seek Approval in T-cell lymphoma

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Citius Pharmaceuticals shared positive topline data Wednesday from its Phase III clinical trial of cancer immunotherapy I/Ontak (denileukin diftitox). The company plans to file a biologics license application (BLA) with the U.S. Food and Drug Administration in the second half of 2022 based on these results.

The Phase III study that evaluated the efficacy and safety of I/Ontak was completed in December 2021. The trial enrolled patients with persistent or recurrent cutaneous T-cell lymphoma (CTCL), a rare type of blood cancer that begins in T-cells, which develop abnormalities that result in T-cells attacking the skin. The trial was conducted in two parts, with part one evaluating the optimal dose of the therapeutic while part two enrolled 91 patients to further evaluate efficacy.

A total of 71 subjects from both parts of the study with persistent or recurrent CTCL were assessed for efficacy, with 69 subjects included in the Primary Efficacy Analysis Set. The primary outcome measured was Objective Response Rate (ORR), which assesses the proportion of patients with a significant reduction in tumor size that can be classified as having a partial or complete response to the therapeutic. Results from the trial showed that patients taking the therapeutic achieved an ORR of 42.3%, meaning almost half of the participants achieved a partial or complete response to the therapeutic.

"If approved, we believe this biologic with its observed efficacy and safety data, and which is already approved for CTCL and peripheral T-cell lymphoma (PTCL) patients in Japan, would arm oncologists in the U.S. with an important additional treatment option for this devastating orphan disease," said Dr. Myron Czuczman, chief medical officer of Citius.

I/Ontak is an engineered interleukin-2 (IL-2) diphtheria toxin fusion protein. The drug specifically binds to IL-2 receptors on the surface of cells, which are receptors that play a central role in the induction of immune responses. Once bound to the receptor, diphtheria toxin fragments enter the cell, inhibiting protein synthesis. Inhibiting protein synthesis allows the drug to eliminate immunosuppressive regulatory T-cells and malignant T-cells, which can activate the patient’s immune response against their tumors.

In 2008, the U.S. FDA approved Ontak for the treatment of CTCL. I/Ontak is a purified and more bioactive formulation of Ontak. Results from clinical trials have supported that the new formulation of the immunotherapy is consistent with the prior formula, with no new safety concerns being found by Citius and overall rates of adverse events being comparable.

In addition to submitting a BLA to the FDA, Citius is anticipated to share full detailed results at an upcoming scientific conference and publish its findings.

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