TuHURA Reports Early Responses in Deep-Seated Merkel Cell Cancer Study

Key Points

• TuHURA reported confirmed partial responses in all three evaluable frontline patients with deep-seated metastatic Merkel cell carcinoma treated with IFx-2.0 plus a checkpoint inhibitor; responses persisted through 24 weeks, with no serious adverse events reported.
• The ongoing Phase 1b study is evaluating CT-, ultrasound- or palpation-guided injections into difficult-to-access tumors. TuHURA plans to enroll 10–12 patients, with an initial assessment potentially supporting regulatory discussions with the FDA later in the year.
• TuHURA’s randomized Phase III trial of IFx-2.0 plus pembrolizumab is expanding, with 22 of 25 initially targeted sites activated and additional sites coming online; enrollment completion is expected in the third or fourth quarter of next year.

TuHURA Biosciences NASDAQ: HURA presented preliminary results from its ongoing open-label Phase 1b study of IFx-2.0 in patients with metastatic Merkel cell carcinoma, or MCC, reporting confirmed partial responses in the first three evaluable patients treated in the frontline setting.

Speaking during a discussion hosted by Rodman & Renshaw, President and CEO Jim Bianco said the study is examining whether IFx-2.0 can be delivered safely into large, deep-seated tumors using CT- or ultrasound-guided injections. Patients receive IFx-2.0 weekly for three doses alongside a checkpoint inhibitor, including pembrolizumab, marketed as Keytruda, on its standard every-three-week schedule.

MCC is an aggressive skin cancer with approximately 3,800 new U.S. diagnoses annually, Bianco said. He described a subset of patients who initially present with Stage IV disease involving deeper lesions in organs, muscle or other tissues. These patients may not be eligible for TuHURA’s ongoing Phase III trial, which requires tumors accessible by a relatively small injection needle.

Early responses in deep-seated disease

Bianco described confirmed partial responses at both 12 and 24 weeks in three patients enrolled at different sites. According to the company, no serious adverse events were reported in those patients.

• A 78-year-old man with Stage IV MCC involving an intramuscular gluteal lesion, pelvic lymph nodes and lungs received CT-guided IFx-2.0 injections and pembrolizumab. Bianco said the patient achieved a confirmed partial response, with approximately a 60% reduction in tumor size at weeks 12 and 24.
• A 79-year-old woman with metastatic disease involving the liver and cervical lymph nodes received ultrasound-guided injections into cervical lymph nodes along with pembrolizumab. The company reported a confirmed partial response at 12 weeks that remained present at 24 weeks. Bianco said the patient experienced improvement in swallowing symptoms as a neck mass regressed.
• A 61-year-old woman with a soft-tissue lesion in her right lower extremity and paraspinal disease received palpation-guided IFx-2.0 and a combination of ipilimumab and nivolumab. The company reported a confirmed partial response at 12 weeks that was ongoing at 24 weeks, with no serious adverse events or treatment-emergent adverse events reported.

A fourth patient, an 88-year-old man with liver metastases, had received three CT-guided injections into liver lesions and was awaiting the protocol-specified 12-week response assessment. Bianco said no serious adverse events had been reported in that patient. He added that the company was encouraged by the patient’s progress but had not yet reported a RECIST-based response.

Study rationale and development plans

Bianco said the study was designed to assess the feasibility and safety of radiologically guided administration as well as objective tumor response and duration of response under RECIST criteria. He said the preliminary results may offer an indication of how IFx-2.0 could perform with a checkpoint inhibitor in a frontline setting, although he cautioned that additional patients will be needed.

The company previously studied IFx-2.0 in patients whose MCC had progressed after treatment with checkpoint inhibitors. In that earlier study, Bianco said five of eight patients achieved durable major anti-tumor responses after receiving IFx-2.0 followed by rechallenge with pembrolizumab or avelumab. Those responses lasted an average of 23 months, with some lasting as long as 33 months, according to Bianco.

TuHURA’s current randomized, placebo-controlled Phase III trial is comparing IFx-2.0 plus pembrolizumab with pembrolizumab plus placebo in frontline Stage III/IV MCC. Bianco said the program was designed following discussions with the U.S. Food and Drug Administration under the agency’s Project FrontRunner initiative, which encourages development of cancer treatments earlier in the treatment course.

The company expects to enroll 10 to 12 patients in the deep-seated-disease study for an initial assessment. Bianco said TuHURA expects to have at least eight patients enrolled by the first quarter and expects all 12 patients to have at least 12 weeks of follow-up by midyear. The company could discuss potential regulatory options with the FDA in the second half of the year if the data continue to show favorable safety, feasibility and response findings.

Phase III enrollment outlook

For the Phase III trial, Bianco said TuHURA has activated 22 of an initially targeted 25 sites and has another 21 sites in the process of coming online. The company has also added Australia to the program. TuHURA’s current guidance calls for completing enrollment in the third or fourth quarter of next year.

About TuHURA Biosciences (NASDAQ:HURA)

TuHURA Biosciences, Inc is a clinical-stage biotechnology company focused on developing immunotherapies for cancer. The company's research is directed toward treatments intended to address mechanisms that enable tumors to evade the immune system and resist existing cancer therapies.

TuHURA's lead product candidate, IFx-2, is an investigational cancer immunotherapy designed for intratumoral administration. The program is intended to stimulate a broader anti-tumor immune response and potentially improve the effectiveness of immune checkpoint inhibitors and other established treatments.

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