TuHURA and Kintara Report Positive Phase 1b Results for IFx-2.0 in Resistant Advanced MCC and cSCC

TuHURA Biosciences, Inc. and Kintara Therapeutics, Inc. have announced promising results from a Phase 1b clinical trial assessing TuHURA’s lead candidate, IFx-2.0, for patients with advanced or metastatic Merkel Cell Carcinoma (MCC) and Cutaneous Squamous Cell Carcinoma (cSCC). Presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting, the data showed that IFx-2.0 was safe and well-tolerated with weekly dosing over three weeks.

The study specifically focused on patients with primary resistance to immune checkpoint inhibitors (ICIs). Eighty percent (80%) of ICI-naïve patients with advanced MCC, who had previously not responded to pembrolizumab or avelumab, achieved durable Complete Response (CR), pathologic CR, or Partial Response (PR) following IFx-2.0 therapy and subsequent rechallenge with an anti-PD(L)-1 checkpoint inhibitor.

Dr. James Bianco, CEO of TuHURA, highlighted that IFx-2.0 demonstrated the ability to overcome ICI resistance in 63% of advanced MCC patients. This includes those who had progressed after anti-PD1 therapy and combination anti-PD1/CTLA-4 therapy, and in some cases, chemotherapy and other investigational treatments. Particularly notable were seven patients with no prior systemic or investigational therapies. Five of these patients progressed within 3.8 months on single-agent anti-PD(L)-1 therapy, after which IFx-2.0 was administered. Following IFx-2.0 therapy and rechallenge with an anti-PD(L)-1 agent, four of these five patients achieved a durable objective response, with responses lasting on average 25 months, and two ongoing at 19 and 23 months.

In two other patients who had progressed on both anti-PD-1 therapy and combination anti-PD1/CTLA4 therapy, one achieved a partial response lasting six months after IFx-2.0 treatment and subsequent rechallenge with anti-PD-1 therapy. These outcomes have laid the groundwork for TuHURA’s upcoming Phase 3 trial, which will evaluate IFx-2.0 in combination with Keytruda® (pembrolizumab) as a first-line treatment for advanced or metastatic MCC. The Phase 3 trial is scheduled to begin enrollment in the second half of 2024 under the FDA's Accelerated Approval Pathway.

TuHURA's IFx-2.0 is a personalized cancer vaccine that uses a patient's own tumor to prime the immune system. The vaccine involves injecting a small amount of plasmid DNA (pDNA) into the tumor, encoding an immunogenic bacterial protein, making the tumor appear like a bacterium. This approach is designed to trigger the patient's innate immune response against the tumor, regardless of its previous ability to escape immune detection.

The Phase 1b study’s primary goal was to establish the safety and feasibility of repeated IFx-2.0 administrations. The study met its primary safety objective, with over 80% of participants completing the planned therapy. An exploratory analysis showed that 63% of MCC patients treated with standard ICI agents immediately after IFx-2.0 therapy experienced durable disease control, indicating an immune priming effect.

Following the trial, a merger agreement between TuHURA and Kintara has been announced, aiming to combine resources to advance a diversified late-stage oncology pipeline. The merger is expected to conclude in the third quarter of 2024, subject to customary closing conditions, including stockholder approvals. The combined company will focus on advancing TuHURA’s personalized cancer vaccines and first-in-class bi-functional Antibody Drug Conjugates (ADCs), designed to enhance the effectiveness of current immunotherapies.

TuHURA Biosciences, Inc. specializes in developing novel immuno-oncology technologies to overcome resistance to cancer immunotherapy, particularly through their lead candidate, IFx-2.0. Kintara, based in San Diego, focuses on developing novel cancer therapies with a lead program, REM-001 Therapy, for cutaneous metastatic breast cancer.