Rezolute's second Phase III trial of ersodetug, this time in tumour hyperinsulinism (HI), is yielding more promising data, prompting the company's stock to rise by more than 10%.

Eight of the 16 planned patients with tumour HI have been treated with ersodetug, a fully human monoclonal antibody (mAb), in the study (NCT06881992).

Of those, six have already met the responder criteria for the study's primary endpoint, defined as the number of patients achieving at least a 50% reduction from baseline in intravenous glucose requirements (glucose infusion rate; GIR) within eight weeks. All these patients also achieved a complete discontinuation of intravenous glucose requirements with the administration of ersodetug.

One of the eight enrolled participants withdrew study consent and discontinued ersodetug and all other non-palliative therapies prior to completion of the pivotal treatment phase. This patient had Stage 4 metastatic colon cancer and a poor Eastern Cooperative Oncology Group performance status (ECOG 4). The participant elected to be discharged from the hospital to receive hospice care at home, where they died one week later due to cancer progression.

The final patient was recently enrolled and is still dosing in the pivotal phase of the study.

All six who completed the pivotal treatment period have elected to continue into the open-label extension, with a cumulative treatment duration of up to six months.

Ersodetug has been well-tolerated in the pivotal and extension phases of the study, with no drug-related adverse events or other safety findings reported to date.

Rezolute's stock, listed on the Nasdaq exchange, was up 10.8% on 2 June, from a 1 June close of $3.61 to a 2 June close of $4.00 following the announcement. The pre-market is also estimating a further 9.25% rise (correct as at 5.43am ET).

Dr Brian Roberts, CMO of Rezolute, said: "These results reveal the clinically impactful hypoglycaemia-correcting activity of ersodetug in an unbiased GIR assessment in patients with HI caused by varying tumour types. This further highlights the aberrant outcome from the recently completed randomised, placebo-controlled, Phase III sunRIZE study in paediatric congenital HI, where we believe that self-monitored glycaemic measures were confounded by divergent caretaker behaviours stemming from functional unblinding to treatment status by real-time glucose monitoring."

Rezolute announced that the sunRIZE trial (NCT06208215) failed to meet its primary or key secondary endpoints in December 2025. At the time, the company's stock crashed by 88.75% from a 10 December close of $10.94 to an 11 December opening of $1.23. There was a very slight increase during the day, with the company's stock eventually closing at $1.40.