52-Week Topline Results from 16-Week Blinded Treatment Extension of REZOLVE-AA Demonstrate Deepening of Responses in Severe-to-Very-Severe Alopecia Areata with Rezpegaldesleukin

Rhea-AI Summary

Nektar Therapeutics (Nasdaq: NKTR) reported 52-week topline results from a 16-week blinded extension of the Phase 2b REZOLVE-AA study of rezpegaldesleukin in severe-to-very-severe alopecia areata. Continued twice-monthly dosing increased responder rates (SALT≤20, SALT30, SALT50) with a favorable safety profile and 94% completion.

Low-dose and high-dose arms reached 25.8% and 27.6% SALT≤20 at week 52 versus 6.7% placebo (p=0.049); safety remained mostly mild-to-moderate TEAEs.

Positive

• SALT≤20 increased to 25.8% (18 µg/kg)
• SALT≤20 increased to 27.6% (24 µg/kg)
• SALT50 of 37.7% and 38.8% in treatment arms
• 94% of extension patients completed 52 weeks
• Favorable safety profile; mostly mild-to-moderate TEAEs

Negative

• Extension cohort was small: 31 patients total
• Placebo continuation arm was very small: 4 patients
• Primary comparison p-value: 0.049 (marginal significance)

News Market Reaction – NKTR

+18.25% 4.0x vol

24 alerts

+18.25% Session close to close

+22.7% Peak in 7 hr 48 min

$3.13B Market Cap

4.0x Rel. Volume

In the Apr 20 session, NKTR gained 18.25%, reflecting a significant positive market reaction. Argus tracked a peak move of +22.7% during that session. Our momentum scanner triggered 24 alerts that day, indicating elevated trading interest and price volatility. Trading volume was very high at 4.0x the daily average, suggesting strong buying interest.

Data tracked by StockTitan Argus on the day of publication.

Market Context

The stock surged +18.3% in the session following this news. A strong positive reaction aligns with p...

Analysis

The stock surged +18.3% in the session following this news. A strong positive reaction aligns with prior episodes where clinical data on rezpegaldesleukin drove substantial moves, including an average historical swing of 57.94% on similar trial headlines. However, reactions to past updates have been inconsistent, with several negative responses despite seemingly favorable news. Investors would have needed to weigh dilution from past financings, insider selling patterns, and the typical volatility around biotech trial milestones when assessing sustainability.

Key Figures

New SALT≤20 responders: 29% (18 µg/kg), 31% (24 µg/kg) SALT≤20 at Week 52: 25.8% low dose, 27.6% high dose, 6.7% placebo SALT≤30 at Week 52: 30.2% low dose, 35.0% high dose, 8.4% placebo +5 more

8 metrics

New SALT≤20 responders 29% (18 µg/kg), 31% (24 µg/kg) Week 36–52 extension, active arms vs 0% placebo

SALT≤20 at Week 52 25.8% low dose, 27.6% high dose, 6.7% placebo Overall REZOLVE-AA population at 52 weeks, p=0.049

SALT≤30 at Week 52 30.2% low dose, 35.0% high dose, 8.4% placebo Overall REZOLVE-AA population at 52 weeks, p=0.023

SALT50 at Week 52 37.7% low dose, 38.8% high dose, 13.6% placebo ≥50% improvement in SALT from baseline

SALT30 at Week 52 45.6% low dose, 47.6% high dose, 24.2% placebo ≥30% improvement in SALT from baseline

Extension population 31 total (27 active, 4 placebo) Blinded 16-week treatment extension cohort

Baseline SALT scores 78.5 treatment, 76.6 placebo Mean Severity of Alopecia Tool at study entry

Completion rate 94% completed 52 weeks Patients in blinded 16-week extension period

Previous Clinical trial Reports

5 past events · Latest: Jul 29 (Positive)

Same Type Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Jul 29	Fast Track designation	Positive	-3.1%	FDA Fast Track status for rezpegaldesleukin in severe alopecia areata.
Jun 24	Positive Phase 2b data	Positive	+156.3%	REZOLVE-AD Phase 2b met primary and key secondary endpoints with strong efficacy.
Jun 23	Data call scheduled	Neutral	+156.3%	Announcement of investor call to present REZOLVE-AD top-line induction data.
Feb 26	Enrollment completion	Neutral	-10.4%	Completion of target enrollment in REZOLVE-AA Phase 2b alopecia areata trial.
Feb 24	New T1D trial pact	Positive	-9.3%	Collaboration to study rezpegaldesleukin in new onset type 1 diabetes.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

Clinical trial news for rezpegaldesleukin has produced large but inconsistent moves, including one very large upside reaction and several negative or muted responses, highlighting event-driven volatility.

Recent Company History

Over the past year, Nektar has steadily advanced rezpegaldesleukin across multiple immune-mediated indications. Key steps included completing REZOLVE-AA enrollment in Feb 2025, initiating a Type 1 diabetes collaboration, and securing FDA Fast Track for severe alopecia areata in Jul 2025. Positive Phase 2b atopic dermatitis data in Jun 2025 triggered a +156.29% move, contrasting with negative reactions to other clinical updates. Today’s 52-week REZOLVE-AA extension data fits into this broader efficacy and safety narrative for REZPEG.

Key Terms

alopecia areata, phase 2b, severity of alopecia tool (salt), placebo, +4 more

8 terms

alopecia areata medical

"in patients with severe-to-very-severe alopecia areata."

Alopecia areata is an autoimmune condition in which the body's immune system mistakenly attacks hair follicles, causing round patches of hair loss on the scalp or body; severity ranges from small spots to widespread baldness. Investors watch it because successful treatments, clinical trial results, regulatory approvals, or shifts in prevalence can create or shrink markets for drugs and therapies, affecting the value of companies developing remedies—think of it as demand risk and regulatory risk for hair-loss products.

phase 2b medical

"in its Phase 2b REZOLVE-AA study."

Phase 2b is a stage in the development of a new medicine or treatment where researchers test its effectiveness and safety in a larger group of people. This step helps determine whether the treatment works well enough to move forward and if it has manageable side effects, which is important for investors because successful results can lead to potential approval and market opportunity.

severity of alopecia tool (salt) medical

"Mean baseline Severity of Alopecia Tool (SALT) Scores for patients"

A standardized scoring system that quantifies how much scalp hair a person has lost by estimating the percentage of hair missing across different parts of the head. Investors care because SALT scores are used as a clear, objective measure of whether a hair-loss treatment is effective in clinical trials; consistent improvements on the SALT can drive regulatory approval, boost trial value, and influence a therapy’s commercial prospects, much like a consistent fuel-efficiency test validates a new car model.

placebo medical

"two rezpegaldesleukin doses or placebo, administered as twice-monthly"

A placebo is an inactive pill, injection or procedure that looks and feels like the real treatment but contains no therapeutic ingredient, often called a sugar pill. Investors care because comparing a drug to a placebo reveals whether observed benefits come from the medicine itself or from expectation; clear superiority over placebo reduces regulatory and commercial risk, much like a blind taste test proves a new recipe really tastes better.

subcutaneous medical

"administered as twice-monthly subcutaneous injections."

Subcutaneous means situated or applied just beneath the skin. In finance, the term can describe processes or investments that are hidden or not immediately visible, much like something placed under the skin that isn't easily seen from the outside. Recognizing subcutaneous activities helps investors understand underlying factors that may influence markets or asset values over time.

t regulatory cell (treg) medical

"a first-in-class IL-2 pathway agonist and regulatory T-cell (Treg) biologic"

T regulatory cells (Tregs) are a specialized type of immune cell that act like traffic controllers, calming or stopping other immune responses to prevent excessive inflammation or autoimmune damage. For investors, Tregs matter because therapies or diagnostics that boost or block their activity can change the course of autoimmune diseases, transplant rejection, or cancer treatments, affecting a drug’s potential market, regulatory risk, and clinical trial outcomes.

treatment-emergent adverse events (teaes) medical

"Nearly all treatment-emergent adverse events (TEAEs) were mild-to-moderate"

Adverse events that first appear or worsen after a patient starts a medical treatment; they are the new or intensified negative effects linked in time to taking the drug or therapy. Investors care because the number and severity of these events shape regulators’ decisions, drug labeling, patient uptake and potential legal or cost risks—think of them like customer complaints that can slow sales, trigger recalls, or change a product’s value.

injection site reactions (isr) medical

"The most common TEAEs were injection site reactions (ISR) with the majority"

A localized physical reaction—such as redness, swelling, pain, itching or bruising—where a drug or vaccine is injected into the body. Investors care because frequent or severe injection site reactions can affect a treatment’s safety profile, regulatory review, patient acceptance and labeling, which in turn can influence sales, market uptake and potential liability; think of it like a recurring irritation at the spot where a patch or plaster is repeatedly applied.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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29% and 31% of patients in the 18 µg/kg and 24 µg/kg extension arms, respectively, achieved new SALT Score ≤20 from week 36 to week 52 with continued twice-monthly treatment

Increasing proportions of patients achieved clinically meaningful hair growth thresholds across numerous SALT measurements with 94% of patients completing treatment extension

Favorable safety profile with twice-monthly dosing maintained throughout 52 weeks, consistent with previously reported results

Results support advancement of rezpegaldesleukin into late-stage development in alopecia areata

SAN FRANCISCO, April 20, 2026 /PRNewswire/ -- Nektar Therapeutics (Nasdaq: NKTR), a clinical-stage biotechnology company focused on development of novel immunology therapies, today announced new results from a blinded 16-week treatment extension period in its Phase 2b REZOLVE-AA study. The study is evaluating investigational rezpegaldesleukin, a first-in-class IL-2 pathway agonist and regulatory T-cell (Treg) biologic, in patients with severe-to-very-severe alopecia areata.

REZOLVE-AA is a global study being conducted in 92 patients with severe-to-very-severe alopecia areata. During the initial 36-week induction phase, patients were randomized (3:3:2) to receive one of two rezpegaldesleukin doses or placebo, administered as twice-monthly subcutaneous injections. Mean baseline Severity of Alopecia Tool (SALT) Scores for patients enrolled in the study were 78.5 in the rezpegaldesleukin treatment arms as compared to 76.6 in placebo. Median time from onset of disease was 6.9 years in the treatment arms and 6.1 years in placebo. Following completion of the induction phase, patients with a SALT Score greater than 20 at week 36 who also demonstrated hair growth were eligible to continue on rezpegaldesleukin at their induction dose level in a blinded 16-week exploratory treatment extension through week 52.

Extended Twice-Monthly Treatment with Rezpegaldesleukin Improved SALT Scores at 52 Weeks

A total of 31 patients continued into the blinded 16-week treatment extension period with 27 patients in the twice-monthly rezpegaldesleukin dose arms (low dose of 18 µg/kg, n=14) and (high dose of 24 µg/kg, n=13) and 4 patients continuing in the placebo arm.

From week 36 to week 52, 29% of patients at low dose and 31% of patients at high dose achieved new SALT Score ≤20 responses as compared to none in the placebo arm. A SALT Score ≤20 is achieved when a patient has 80% or more of their scalp covered by hair.

At week 52 for overall study population¹, patients who achieved SALT Score ≤20 were 25.8% in low dose rezpegaldesleukin arm (versus 14.8% at week 36²) and 27.6% in high dose rezpegaldesleukin arm (versus 15.6% at week 36²) as compared to 6.7% with placebo (versus 6.7% at week 36²) with a p-value of 0.049.³

"The new SALT≤20 responders in this set of patients treated out to 52 weeks reflect how the T regulatory cell mechanism of REZPEG can have more clinical benefit over time, a phenomenon the investigators observed in the Phase 2 study in atopic dermatitis as well," said Jonathan Silverberg, MD, PhD, MPH, Professor of Dermatology at The George Washington University School of Medicine and Health Sciences. "Given the prescribing and safety limitations of JAK inhibitors, these new data point to the potential for rezpegaldesleukin to be the first safe and effective biologic in alopecia areata, which may completely transform the management of the disease."

At week 52 for overall study population¹, patients who achieved SALT Score ≤30 were 30.2% in low dose rezpegaldesleukin arm (versus 21.9% at week 36²) and 35.0% in high dose rezpegaldesleukin arm (versus 29.0% at week 36²) as compared to 8.4% with placebo (versus 8.4% at week 36²), with a p-value of 0.023.³ A SALT Score ≤30 is achieved when a patient has 70% or more of their scalp covered by hair.

"These extension treatment data to 52 weeks demonstrate the potential of rezpegaldesleukin to deliver truly meaningful clinical outcomes for patients with severe-to-very-severe alopecia areata," said David Rosmarin, MD, Chair of the Department of Dermatology and Associate Professor of Dermatology at the Indiana University School of Medicine. "We are in need of a new mechanism for a first-line systemic treatment option as an alternative to the class of agents currently approved for patients. The safety profile combined with a significantly higher number of patients achieving SALT Score ≤20 with continued treatment reinforce that this first-in-class Treg mechanism could emerge as the treatment of choice for patients with alopecia areata, including also those with moderate disease."

At week 52 for overall study population¹, patients who achieved SALT₅₀ (showing at least a 50% improvement in SALT Score from baseline) were 37.7% in low dose rezpegaldesleukin arm and 38.8% in high dose rezpegaldesleukin arm as compared to 13.6% with placebo.¹

At week 52 for overall study population¹, patients who achieved SALT₃₀ (showing at least a 30% improvement in SALT Score from baseline) were 45.6% in low dose rezpegaldesleukin arm and 47.6% in high dose rezpegaldesleukin arm as compared to 24.2% with placebo.¹

"We are excited that rezpegaldesleukin has now demonstrated great promise in two large immune-mediated disease settings as we advance into registrational trials," said Howard W. Robin, President and CEO of Nektar Therapeutics. "As a completely novel mechanism of action in immunology which leverages T regulatory cell biology, we've shown that rezpegaldesleukin could offer compelling efficacy and safety advantages for patients battling various auto-immune conditions."

Nektar plans to submit the REZOLVE-AA results for presentation at a medical conference in 2026.

Rezpegaldesleukin Well Tolerated with Safety Profile Consistent with Previously Reported Results

Consistent with prior studies, a favorable safety and tolerability profile was observed with longer twice-monthly dosing for 52 weeks. Nearly all treatment-emergent adverse events (TEAEs) were mild-to-moderate in severity which resolved without intervention. 94% of patients in the blinded 16-week treatment extension completed 52 weeks of treatment and there were no patients who discontinued during the extension because of a TEAE. The most common TEAEs were injection site reactions (ISR) with the majority being mild to moderate in nature (erythema) which self-resolved within 5 days. There were no patients in the study who discontinued treatment due to an injection site reaction (ISR). 

About REZOLVE-AA

The REZOLVE-AA (NCT06340360) study enrolled patients with severe-to-very-severe alopecia areata who have not previously been treated with a JAK inhibitor or other biologic. Patients were randomized across two different dose regimens of rezpegaldesleukin or placebo. The trial completed enrollment in February 2025, with patients enrolled across approximately 30 sites globally, with 64% of patients in Poland; 23% in Canada; and 13% in the United States.

About Rezpegaldesleukin

Autoimmune and inflammatory diseases cause the immune system to mistakenly attack and damage healthy cells in a person's body. A failure of the body's self-tolerance mechanisms enables the formation of the pathogenic T lymphocytes that conduct this attack. Rezpegaldesleukin is a potential first-in-class resolution therapeutic that may address this underlying immune system imbalance in people with many autoimmune and inflammatory conditions. It targets the interleukin-2 receptor complex in the body to stimulate proliferation of powerful inhibitory immune cells known as regulatory T cells. By activating these cells, rezpegaldesleukin may act to bring the immune system back into balance.

In February 2025, the U.S. Food and Drug Administration (FDA) granted Fast Track designation for rezpegaldesleukin for the treatment of adult and pediatric patients 12 years of age and older with moderate-to-severe atopic dermatitis whose disease is not adequately controlled with topical prescription therapies or when those therapies are not advisable. In July 2025, the FDA granted Fast Track designation for rezpegaldesleukin for the treatment of severe alopecia areata (AA) in adults and pediatric patients 12 years of age and older who weigh at least 40 kg.

Rezpegaldesleukin is being developed as a self-administered injection for a number of autoimmune and inflammatory diseases, including atopic dermatitis, alopecia areata and Type 1 diabetes. It is wholly owned by Nektar Therapeutics.

About Alopecia Areata

Alopecia areata is a disease where a patient's own immune system attacks hair follicles resulting in hair loss.⁴ The lifetime incidence of alopecia areata is 2% in both men and women.⁴ Nearly 6.7 million people in the U.S. and 160 million worldwide develop alopecia areata in their lifetime. About 700,000 people in the U.S. currently have some form of alopecia areata.⁵ It is often associated with other auto-immune conditions as well as depression and anxiety.⁶ The disease has a tremendous impact on quality of life for patients.⁶ Available therapies for alopecia are not durable and have high relapse rates and there is an urgent unmet medical need for novel, more effective therapies for patients.

About Nektar Therapeutics

Nektar Therapeutics is a clinical-stage biotechnology company focused on developing treatments that address the underlying immunological dysfunction in autoimmune and chronic inflammatory diseases. Nektar's lead product candidate, rezpegaldesleukin (REZPEG, or NKTR-358), is a novel, first-in-class regulatory T cell stimulator being evaluated in one Phase 2b clinical trial in atopic dermatitis, one Phase 2b clinical trial in alopecia areata, and one Phase 2 clinical trial in Type 1 diabetes mellitus. Nektar's pipeline also includes a preclinical bivalent tumor necrosis factor receptor type II (TNFR2) antibody and bispecific programs, NKTR-0165 and NKTR-0166, and a modified hematopoietic colony stimulating factor (CSF) protein, NKTR-422.

Nektar is headquartered in San Francisco, California. For further information, visit www.nektar.com and follow us on LinkedIn.

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements which can be identified by words such as: "can," "develop," "potential," "expand," "address," "may," "plan" and similar references to future periods. Examples of forward-looking statements include, among others, statements regarding the safety and efficacy profile and therapeutic potential of, and future development plans for, rezpegaldesleukin, NKTR-0165, NKTR-0166, and NKTR-422, and potential patient preferences and market adoption related thereto, and plans and timing of future data releases. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based only on our current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies, anticipated events and trends, the economy and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict and many of which are outside of our control. Our actual results may differ materially from those indicated in the forward-looking statements. Therefore, you should not rely on any of these forward-looking statements. Important factors that could cause our actual results to differ materially from those indicated in the forward-looking statements include, among others: (i) our statements regarding the therapeutic potential of rezpegaldesleukin, NKTR-0165, NKTR-0166 and NKTR-422 are based on preclinical and clinical findings and observations and are subject to change as research and development continue; (ii) rezpegaldesleukin, NKTR-0165, NKTR-0166 and NKTR-422 are investigational agents and continued research and development for these drug candidates is subject to substantial risks, including negative safety and efficacy findings in future clinical studies (notwithstanding positive findings in earlier preclinical and clinical studies); (iii) rezpegaldesleukin, NKTR-0165, NKTR-0166 and NKTR-422 are in clinical development and the risk of failure is high and can unexpectedly occur at any stage prior to regulatory approval; (iv) data reported from ongoing clinical trials are necessarily interim data only and the final results will change based on continuing observations; (v) the timing of the commencement or end of clinical trials and the availability of clinical data may be delayed or unsuccessful due to regulatory delays, slower than anticipated patient enrollment, manufacturing challenges, changing standards of care, evolving regulatory requirements, clinical trial design, clinical outcomes, competitive factors, or delay or failure in ultimately obtaining regulatory approval in one or more important markets; (vi) a Fast Track designation does not increase the likelihood that rezpegaldesleukin will receive marketing approval in the United States; (vii) patents may not issue from our patent applications for our drug candidates, patents that have issued may not be enforceable, or additional intellectual property licenses from third parties may be required; and (viii) certain other important risks and uncertainties set forth in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 13, 2026. Any forward-looking statement made by us in this press release is based only on information currently available to us and speaks only as of the date on which it is made. We undertake no obligation to update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise.

For Investors:

Vivian Wu
628-895-0661
VWu@nektar.com

Corey Davis, Ph.D.
LifeSci Advisors
212-915-2577
cdavis@lifesciadvisors.com 

For Media:

Susan Roberts
LifeSci Communications
202-779-0929
sroberts@lifescicomms.com

1. For 52-week analysis, data for week 0-36 in modified intent-to-treat (mITT) adapted population are imputed following primary estimand. The mITT adapted population excludes 4 patients with major study eligibility violations before week 36. These patients did not continue into the blinded 16-week treatment extension. Data for patients in non-treatment extension set in week 40, 44, 48 and 52 are carried forward from week 36 data. Missing data for patients in treatment extension set for week 40, 44, 48 and 52 are imputed using the multiple imputation method. Descriptive summary statistics (p-values) are exploratory analyses.
2. Rosmarin et al. (2026, March 27-31). Novel Regulatory T-cell enhancing Biologic Rezpegaldesleukin: Phase 2b Efficacy, Safety, and Baseline Severity-Dependent Treatment Response in Moderate-to-Severe Atopic Dermatitis. 2026 American Academy of Dermatology (AAD), Denver, Colorado
3. Primary estimand analysis was used at time of week 36 database lock in mITT adapted population. Patients who used prohibited medications for the treatment of AA or who discontinued treatment due to lack of efficacy were considered nonresponders (using baseline observation carry forward (BLOCF) for continuous endpoints, and nonresponder imputation for binary endpoints), regardless of observed clinical response. Data after patients who discontinued due to other reasons are set to missing and all missing data are imputed using the multiple imputation method.
4. Lintzeri, D.A., Constantinou, A., Hillmann, K., Ghoreschi, K., Vogt, A. and Blume- Peytavi, U. (2022), Alopecia areata – Current understanding and management. JDDG: Journal der Deutschen Dermatologischen Gesellschaft, 20: 59-90. https://doi.org/10.1111/ddg.14689
5. National Alopecia Areata Foundation
6. Alhanshali L, Buontempo MG, Lo Sicco KI, Shapiro J. Alopecia Areata: Burden of Disease, Approach to Treatment, and Current Unmet Needs. Clin Cosmet Investig Dermatol. 2023;16:803-820 https://doi.org/10.2147/CCID.S376096

 

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SOURCE Nektar Therapeutics

FAQ

What were the week‑52 SALT≤20 responder rates for NKTR rezpegaldesleukin in REZOLVE‑AA?

At week 52, 25.8% (18 µg/kg) and 27.6% (24 µg/kg) of patients achieved SALT≤20. According to Nektar, these compare with 6.7% for placebo and reflect additional responders during the 36–52 week blinded extension.

How did rezpegaldesleukin perform on SALT50 and SALT30 at 52 weeks in the NKTR study?

Rezpegaldesleukin showed 37.7%–38.8% SALT50 and 45.6%–47.6% SALT30 at week 52. According to Nektar, both dose arms outperformed placebo, indicating larger proportions reached 30% and 50% improvement from baseline.

What safety and tolerability did Nektar report for twice‑monthly rezpegaldesleukin through 52 weeks?

Safety remained favorable with mostly mild-to-moderate TEAEs; injection site reactions were common but self-resolved. According to Nektar, no patients discontinued during the extension because of a TEAE and tolerability matched prior studies.

How many patients continued into the blinded 16‑week extension of REZOLVE‑AA (NKTR)?

A total of 31 patients entered the blinded 16-week extension: 14 low dose, 13 high dose, and 4 placebo. According to Nektar, 94% of those patients completed 52 weeks of treatment.

Do the REZOLVE‑AA 52‑week results support further development of rezpegaldesleukin (NKTR)?

Nektar indicates the data support advancement into late‑stage development based on increased responder rates and consistent safety. According to Nektar, the results informed plans to submit findings for medical conference presentation and registrational planning.