TuHURA Biosciences (HURA) Study update summary

Trial rationale and design

• Phase 1b/2a, multicenter, open-label study evaluates IFx-2.0 in first-line metastatic MCC with deep-seated or bulky tumors that are difficult to inject with standard-size needles.

• IFx-2.0 0.1 mg is injected into one tumor weekly for 3 weeks; Keytruda begins within 48 hours of the first injection and continues every 3 weeks until progression, toxicity or 2 years.

• Primary endpoint is safety and feasibility 28 days after the final IFx-2.0 dose; secondary RECIST v1.1 efficacy assessments are at 3 and 6 months.

• Ongoing Phase 3 compares IFx-2.0 plus Keytruda with Keytruda plus placebo in first-line advanced or metastatic MCC; Phase 1b/2a findings may inform, but do not replace, that trial.

Preliminary clinical findings

• All 3 initial patients achieved confirmed partial responses by RECIST v1.1, ongoing at the 6-month assessment; responses were confirmed at weeks 12 and 24.

• CT- or ultrasound-guided IFx-2.0 administration was feasible for large, bulky or deep-seated tumors.

• A 78-year-old man had a reported 60% tumor reduction after CT-guided injection; a 79-year-old woman's neck mass regressed and swallowing was near normal by week 24.

• Four of four treated patients had a favorable safety profile, with no serious adverse events reported.

Safety and development outlook

• Initial enrollment target is 9 patients; additional data are expected in the coming months, with a scientific-conference presentation planned next year.

• If responses remain high, investigators plan to explore expanding enrollment and discuss with the FDA whether the study could supplement Phase 3 if it meets its primary endpoint.

• FDA discussions were anticipated after 24-week follow-up to consider evidence needs for a potential accelerated-approval path or inclusion of deep-seated disease in the label.

• Phase 3 enrollment was guided to finish in the second half of the following year, likely late Q3 or early Q4; 22 of the initial 25 sites were active, with 21 additional sites being brought online.

• Including deep-seated patients could expand the estimated U.S. addressable population from ~2,000 to ~3,140 annually.