RZLT Stock Plummets 79% Month to Date: Here's What You Need to Know

Shares of Rezolute RZLT have plummeted 79.2% so far in December. The massive stock price crash was observed after RZLT reported disappointing top-line data from a late-stage study of its only pipeline candidate, ersodetug, for patients with congenital hyperinsulinism (HI) last week.

Rezolute’s phase III sunRIZE (RZ358-301) study is evaluating ersodetug in HI patients aged 3 months to 45 years who continue to experience hypoglycemia despite standard of care. The study enrolled 63 patients and is testing two dose levels (5 and 10 mg/kg) compared to placebo as add-on therapy, with initial dosing every other week and then every four weeks over a six-month pivotal period.

RZLT’s Phase III Hyperinsulinism Study Data in Detail

Per the data readout, Rezolute’s phase III sunRIZE study did not achieve its primary endpoint, which evaluated the change in average weekly hypoglycemia events measured by self-monitored blood glucose. While the highest ersodetug dose showed an approximate 45% reduction in hypoglycemia events, this effect was not statistically significant compared to placebo, which demonstrated a roughly 40% improvement.

The study also missed its key secondary endpoint assessing the change in average daily time spent in hypoglycemia by continuous glucose monitoring. The 10 mg/kg dose of RZLT’s ersodetug showed an approximate 25% reduction compared with a roughly 5% increase in the placebo group, a difference that was not statistically significant.

In the past six months, shares of Rezolute have plunged 50.4% against the industry’s 22.1% growth.

However, from a pharmacokinetic perspective, the dosing regimen of 5 and 10 mg/kg successfully achieved target drug concentrations across all age groups, supporting the adequacy of the candidate’s dosing strategy.

Safety findings were generally favorable and supportive of ersodetug use in both pediatric and adult patients. While two HI patients experienced serious hypersensitivity reactions that led to early discontinuation, the overall incidence of serious allergic events across the program remains low relative to other biologic or monoclonal antibody therapies.

RZLT’s Next Steps in the Ersodetug Development Program

Following the disappointing phase III HI study data for ersodetug, Rezolute is undertaking a comprehensive review to better understand the results and determine the most appropriate path forward for the program.

The company is also gearing up to meet with the FDA under the candidate’s Breakthrough Therapy status for this indication to discuss next steps for the program.

Beyond HI, Rezolute is advancing ersodetug as a potential treatment for tumor-induced HI, an area of high unmet medical need with limited therapeutic options.

In August 2025, Rezolute aligned with the FDA on a significantly streamlined clinical development path for its phase III registrational program of ersodetug to treat tumor HI. Following the agreement, RZLT initiated the upLIFT study, enrolling up to 16 hospitalized patients, which the FDA considers sufficient to support registration, eliminating the requirement for a randomized placebo-controlled study. Enrollment is currently underway, with top-line data anticipated in the second half of 2026.

Rezolute, Inc. Price and Consensus

Rezolute, Inc. price-consensus-chart | Rezolute, Inc. Quote

RZLT’s Zacks Rank & Other Stocks to Consider

Rezolute currently carries a Zacks Rank #2 (Buy).

Some other top-ranked stocks in the biotech sector are ANI Pharmaceuticals ANIP, CorMedix CRMD and Castle Biosciences CSTL, each sporting a Zacks Rank #1 (Strong Buy) at present. You can see the complete list of today’s Zacks #1 Rank stocks here.

Over the past 60 days, estimates for ANI Pharmaceuticals’ 2025 earnings per share (EPS) have increased from $7.29 to $7.56. Over the same period, EPS estimates for 2026 have surged from $7.81 to $8.08. Shares of ANIP have surged 25.4% in the past six months.

ANI Pharmaceuticals’ earnings beat estimates in each of the trailing four quarters, delivering an average surprise of 21.24%.

Over the past 60 days, estimates for CorMedix’s 2025 EPS have increased from $1.85 to $2.87, while 2026 EPS estimates have risen from $2.49 to $2.88 over the same period. Shares of CRMD have lost 15.8% in the past six months.

CorMedix’s earnings beat estimates in each of the trailing four quarters, with the average surprise being 27.04%.

Over the past 60 days, the loss estimate for Castle Biosciences has narrowed from 65 cents to 34 cents in 2025. Over the same period, loss estimates for 2026 have improved from $2.10 to $1.06. CSTL stock has rallied 106.5% in the past six months.

Castle Biosciences’ earnings beat estimates in three of the trailing four quarters and missed in the remaining quarter, with the average surprise being 66.11%.

Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report

This article originally published on Zacks Investment Research (zacks.com).

Zacks Investment Research