Citius Pharmaceuticals, Inc. (“Citius” or the “Company”) (Nasdaq: CTXR), a late-stage biopharmaceutical company dedicated to the development and commercialization of first-in-class critical care products with a focus on oncology, anti-infective products in adjunct cancer care, unique prescription products, and stem cell therapies, today announced that it has completed patient enrollment in its Pivotal Phase 3 trial of I/ONTAK, an engineered IL-2-diphtheria toxin fusion protein, for the treatment of patients with persistent or recurrent cutaneous T-cell lymphoma (CTCL). The treatment phase for the study has been completed with topline results expected in the first half of 2022 and a biologics license application (BLA) expected to be filed with the U.S. Food and Drug Administration (FDA) in the second half of 2022.
“Completing enrollment in the Pivotal Phase 3 study of I/ONTAK moves us another step closer to expanding treatment options for patients suffering from advanced CTCL. We expect I/ONTAK’s unique mechanism-of-action to offer oncologists an important therapeutic alternative to current targeted therapies which have limited duration of response and are often discontinued due to toxicity. We look forward to reviewing the complete safety and efficacy data and anticipate providing topline results in the first half of next year, followed by a BLA submission in the second half of 2022,” stated Myron Holubiak, Chief Executive Officer of Citius.
A total of 70 patients were enrolled in the main part of the I/ONTAK Phase 3 study, a multicenter, open-label, single-arm Pivotal study of I/ONTAK in participants with recurrent or persistent CTCL (NCT01871727). Positive efficacy data from an initial 21-subject lead-in study supported proceeding with the main study with an optimal dose level of 9 micrograms per kilogram (mcg/kg) of I/ONTAK. Subjects were administered I/ONTAK by intravenous infusion over 60 minutes (+/-10 minutes) on 5 consecutive days per cycle every 21 days.
The primary outcome measure for the main study is the Objective Response Rate (ORR). The ORR is defined as the proportion of subjects with a significant reduction in tumor size that can be classified as achieving either a partial response (PR) or a complete response (CR). The primary endpoint and quality of life analyses of the study will be performed on the combined data set from subjects in the main study plus subjects in the lead-in part of the study who received 9 micrograms per kilogram through the data cutoff date. Multiple secondary endpoints including duration of response, time to response, and safety will be evaluated.
I/ONTAK is a recombinant fusion protein that combines the interleukin-2 (IL-2) receptor binding domain with diphtheria toxin fragments. The agent specifically binds to IL-2 receptors on the cell surface, causing diphtheria toxin fragments that have entered cells to inhibit protein synthesis. I/ONTAK, a purified version of denileukin diftitox, is a reformulation of previously FDA-approved oncology treatment ONTAK®. ONTAK® was marketed in the U.S. from 2008 to 2014, when it was voluntarily withdrawn from the market to enable manufacturing improvements. These improvements resulted in a new formulation, which maintains the same amino acid sequence but features improved purity and bioactivity. The new formulation received regulatory approval in Japan for the treatment of CTCL and PTCL. In 2011 and 2013, the FDA granted orphan drug designation (ODD) to I/ONTAK for the treatment of PTCL and CTCL, respectively, making it eligible for seven years of market exclusivity post-approval.
About Cutaneous T-cell Lymphoma
Cutaneous T-cell lymphoma is a type of cutaneous non-Hodgkin lymphoma (NHL) that comes in a variety of forms and is the most common type of cutaneous lymphoma. In CTCL, T-cells, a type of lymphocyte that plays a role in the immune system, become cancerous and develop into skin lesions, leading to a decrease in the quality of life of patients with this disease due to severe pain and pruritus. Mycosis Fungoides (MF) and Sezary Syndrome (SS) comprise the majority of CTCL cases. Depending on the type of CTCL, the disease may progress slowly and can take anywhere from several years to upwards of ten to reach tumor stage. However, once the disease reaches this stage, the cancer is highly malignant and has usually spread to the lymph nodes and internal organs, resulting in a poor prognosis. Given the duration of the disease, patients typically cycle through multiple systemic agents to control disease progression. CTCL affects men twice as often as women and is typically first diagnosed in patients between the ages of 50 and 60 years of age. Other than allogeneic stem cell transplantation, for which only a small fraction of patients qualify, there is currently no cure for advanced CTCL. Approximately 3,000 new cases are reported in the United States every year, with an estimated 30,000 – 40,000 individuals living with the disease.