Rezolute Ersodetug Hits Phase 3 Endpoint in Tumor HI

Rezolute, Inc. (Nasdaq: RZLT) said on 13 November 2026 that its Phase 3 upLIFT study of ersodetug in tumor hyperinsulinism achieved its primary efficacy endpoint, with 13 of 16 enrolled participants meeting the responder criterion and 12 of those also discontinuing intravenous glucose entirely. The primary endpoint requires the lower bound of the 95% confidence interval to exceed 30%, equivalent to at least 9 responders, or 56% of the 16-participant cohort. Full topline results, including the statistical analysis, are expected by mid-December 2026.

Context — why this matters now

The upLIFT readout arrives as a preliminary signal rather than a final one. Rezolute based the announcement on a 5 November 2026 data evaluation, and the company said the completed study's topline results and formal statistical analysis of the primary endpoint will follow by mid-December 2026. Until that analysis lands, the responder count stands as a raw tally rather than a confirmed significance test.

The company framed the result against its own expanded access program, which it said has produced outcomes over the last few years that these trial results substantially mirror. That comparison matters because expanded access data is not controlled and cannot support approval on its own; the registrational study is what the FDA weighs.

Three participants remain in the pivotal period, two of whom have not yet met the responder criterion. One participant left the study early for home hospice care and died a week later from cancer progression; the company classified that participant as a non-responder for the primary endpoint. That classification is the conservative treatment and it lowers the responder percentage relative to the enrolled base.

Rezolute also disclosed that the FDA recommended filing a Biologics License Application for congenital HI after a pre-BLA meeting. The company said it believes it is positioned to advance both congenital HI and tumor HI into the approval process next year, with FDA discussions planned for the first quarter of 2027.

Data — what the numbers show

The endpoint math is straightforward. A 56% responder rate among 16 participants equals 9 responders, and that is the minimum needed for the lower bound of the 95% confidence interval to clear 30%. Rezolute reported 13 responders, which is 81% of the enrolled cohort, and 12 patients who stopped IV glucose completely.

Measure	Reported	Threshold
Responders	13 of 16 (81%)	At least 9 (56%)
Complete IV glucose discontinuation	12 patients	Not specified
Still in pivotal period	3 patients	—
Classified non-responder	1 patient	—

The enrolled population splits into four participants with non-islet cell tumors and 12 with insulin-secreting malignant islet cell tumors, or insulinomas. Ersodetug was described as well-tolerated across the pivotal and extension phases, with no drug-related safety findings attributed to the therapy. The dosing regimen is 9 mg/kg per week for 8 weeks as an add-on to standard of care, after which participants may continue at a reduced frequency in long-term extension.

The report gives no market capitalization, share price, cash position, or peer comparison, so no valuation or sector-relative figure can be attached to this readout.

Analysis — what it means for markets / sectors / tickers

The exposure here is narrow and concentrated. Rezolute is the sole named issuer tied to ersodetug, so the equity reaction belongs to RZLT alone rather than to a broad metabolic or rare-disease basket. Companies developing therapies for refractory hypoglycemia sit in a small competitive field, and a positive registrational readout in tumor HI narrows the set of credible late-stage entrants.

The second-order effect runs through the approval timeline rather than the revenue line. Rezolute said it expects to discuss both congenital HI and tumor HI with the FDA in the first quarter of 2027 and to potentially submit one or two BLAs in 2027. A dual-track filing would put two distinct patient populations in front of the agency on the same antibody, which raises the value of a clean safety record across the program.

The main limitation is statistical, not clinical. Thirteen responders against a nine-responder bar looks comfortable, but the confidence interval depends on the final denominator and on how the remaining three participants resolve. If the two unresolved participants convert to non-responders, the tally changes; the company has not disclosed the timing of those outcomes. The hospice participant already counts against the total.

Positioning follows the same logic. Holders of RZLT are effectively long a binary regulatory path with a near-term statistical checkpoint in mid-December, while the congenital HI program carries its own separate FDA risk that the company itself flagged in its forward-looking statements.

Outlook — what to watch next

Two dated catalysts sit ahead. The first is the completed upLIFT topline release, including the statistical analysis of the primary endpoint, which the company expects by mid-December 2026. The second is the FDA meeting set for the first quarter of 2027, covering both tumor HI and congenital HI.

On the congenital HI side, the company noted that the FDA recommended a BLA filing after a pre-BLA meeting, but it also cautioned that there is no assurance the agency will agree the sunRIZE program evidence demonstrates a clinically meaningful benefit or supports approval. That caveat applies to the congenital program specifically, not to the tumor HI endpoint just reported.

The report names no price levels, moving averages, or index thresholds, so none are carried here. The operative variable is the responder count once the pivotal period closes.

Frequently Asked Questions

What is tumor hyperinsulinism and why is it hard to treat?

Tumor hyperinsulinism is a rare condition caused by two tumor types: islet cell tumors such as insulinomas, which overproduce insulin, and non-islet cell tumors including hepatocellular carcinoma and soft tissue malignancies, which secrete insulin-like substances such as IGF-2 variants that activate the insulin receptor. Both routes drive hypoglycemia. The company describes high morbidity and mortality in this population and a significant unmet need for therapies directed at the hypoglycemia itself rather than the underlying cancer.

How does ersodetug work differently from treating the tumor?

Ersodetug is a fully human monoclonal antibody that binds allosterically to the insulin receptor, reducing receptor over-activation by insulin and related substances such as IGF-2. Because it acts downstream of pancreatic insulin secretion, paraneoplastic IGF-2 secretion, and entero-incretin pathways, the company said it has the potential to treat refractory hypoglycemia regardless of which form of hyperinsulinism is driving it. It is investigational, and no health authority has approved its safety or efficacy claims.

What does the mid-December 2026 readout actually add?

The November announcement rests on a preliminary data evaluation dated 5 November 2026, which produced a raw responder count. The mid-December release is expected to add the completed study's topline results and the formal statistical analysis of the primary endpoint, including the confidence interval that determines whether the threshold is met. Until that analysis is published, the significance test remains unconfirmed by the company.

Bottom Line

Rezolute cleared its Phase 3 responder bar on preliminary data, but the statistical confirmation and two unresolved patients land by mid-December.

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