Nektar Therapeutics brought a year of data on its alopecia areata drug to the EADV Congress in Vienna on October 1, presenting in two oral sessions and pairing the results with an investor call the same morning. The findings that carried the presentation describe the months after the injections stopped. In the Phase 2b REZOLVE-AA study, patients who reached a SALT score of 20 or below after 52 weeks of treatment mostly held that response through six months off treatment, and the group's best responses kept improving. The share of extension patients at a SALT score of 10 or below, which means close to complete scalp coverage, rose from 7 percent at the end of treatment to 19 percent six months after the last dose. One patient reached full regrowth with no drug on board.
Alopecia areata is an immune attack on hair follicles that affects roughly 700,000 people in the United States at any given time, and the drugs approved for severe cases are daily oral JAK inhibitors whose benefit depends on staying on them. The FDA cleared Litfulo for patients 12 and older in 2023, a year after Olumiant was approved for adults, and the class carries boxed warnings. The withdrawal study inside the baricitinib program documented what happens after patients stop: most lose the regrowth, and retreatment restores it. Nektar's drug is designed to be a different kind of medicine, an injectable given every two weeks that expands regulatory T cells rather than suppressing the immune system broadly, and the durability numbers from Vienna are the first substantial test of whether that difference is real.
The market's first read went the other way. Nektar shares fell 22.4 percent to $46.99 on October 1 as safety questions and the size of the durability cohort dominated the reaction. Expectations had been high going in, and even after the drop the price-to-sales ratio sat near 19, close to double its own historical median, the signature of a stock priced for a pipeline rather than a product.
What the extension added to the 52-week results
The REZOLVE-AA trial randomized 92 adults with severe to very severe disease, defined as a SALT score of 50 or higher, who had not previously taken a JAK inhibitor or biologic. Patients received one of two dose levels of rezpegaldesleukin or placebo as an injection every two weeks, and the primary endpoint was the mean percentage reduction in SALT score at week 36. A SALT score of 20 or below corresponds to 80 percent or more scalp coverage; a score of 10 or below is near complete regrowth.
The protocol let patients who still had a SALT score above 20 at week 36, but who were growing hair, continue blinded treatment through week 52, keeping the placebo group in place so the blinding held. Thirty-one did, 27 of them on the drug. From week 36 to week 52, 29 percent of the low-dose group and 31 percent of the high-dose group newly reached the 20-or-below threshold, and none of the four placebo patients in the extension did. Episode length did not change the result: 29 percent of patients whose current episode had lasted under four years reached the threshold, and 30 percent of those at four years or longer. Everyone then entered a 24-week off-treatment follow-up, which is the window the congress data describe.
The responses that kept building off treatment
The off-treatment period is where these data separate from a routine update. Among patients at a SALT score of 20 or below after 52 weeks of treatment, 75 percent still held that threshold four months after the last injection and 63 percent held it at six months, measured by non-responder imputation.
The company's own presentation reports that the deepest responses kept deepening after dosing ended. Three patients who were at 20 or below at week 52 crossed to 10 or below during the six months off treatment, one of them reaching complete regrowth, and the share of the extension group at 10 or below rose from 7 percent to 19 percent. Among the 27 patients who entered the extension on the drug, 41 percent reached a deeper best response off treatment than on it, and another 22 percent held their week-52 result.
That pattern is what a regulatory T cell mechanism predicts if it works as designed. Rather than holding the immune attack down for as long as the drug is present, it aims to shift the immune system away from attacking hair follicles, and a response that continues to build after dosing ends is the visible signature of that idea. It is also why Nektar says the data support moving to monthly or quarterly maintenance dosing after a year of every-two-week induction.
Six of eight is a hypothesis, not an estimate
The durability percentages rest on eight patients, four in each dose arm. They are the subset that had reached 20 or below after 52 weeks of treatment and entered the off-treatment follow-up, and 75 and 63 percent are fractions of that one group, six of eight and five of eight. Nektar also ran an as-observed analysis of 21 patients who completed the extension and had data at the end of follow-up: 48 percent maintained or further increased their hair regrowth at six months.
The company's own numbers show how much the length of treatment matters. Patients who stopped at 36 weeks, without the extension, kept the 20-or-below threshold at four months in four of six patients with observed data, or 40 percent under the same non-responder accounting used for the headline figures. The longer course looks more durable, but every one of these comparisons comes from a cohort of a few dozen people at most. The extension itself carried 31 patients out of the 92 who started the trial, and the eight-patient group at the center of the durability claim is smaller than the margin of a single patient's regrowth. Alopecia areata can also improve on its own, which is why the trial screened out patients who had shown spontaneous improvement in the six months before enrolling. Eight people is a narrow stage for a disease that waxes and wanes.
The comparison Nektar drew, and labeled as limited
Nektar placed its maintenance figures next to historical low-dose baricitinib data, which it said showed 30 percent of patients keeping the threshold at four months off treatment and 20 percent at six months, against 75 and 63 percent for its own drug. The slides label the comparison as cross-trial, drawn from different studies with different statistical handling: the baricitinib withdrawal analysis carried last observations forward, while the Nektar figures count missing data as failures, a stricter approach.
Some of that caution is the usual hedging around any comparison without a shared control arm. Some of it is load-bearing. A cross-trial comparison cannot show that one drug's durability beats another's; it can only make the case that the question deserves a head-to-head look. The relapse pattern in the JAK class is documented well enough that the baricitinib data make that case on their own.
The safety table behind the selloff
The durability discussion arrived alongside a safety critique. William Blair's Andy Hsieh noted that 92 percent of patients experienced injection-site reactions, against 30 percent on placebo, and flagged higher rates of upper respiratory infection, nasopharyngitis and joint pain, calling the injection-site burden an overhang on the drug's commercial profile. Nektar's 52-week safety summary describes nearly all adverse events as mild to moderate and self-resolving, including the injection-site reactions, with 94 percent of extension patients completing 52 weeks of treatment and no discontinuations during the extension because of an adverse event.
The divide is not about whether the events happened. It is about what a 92 percent rate of mostly transient skin reactions means for a drug meant to be given every two weeks for years, and for patients choosing between an injection they can give themselves at home and a daily pill with a boxed warning. The company makes the same comparison from the other direction, arguing that a biologic with infrequent dosing sidesteps the lab monitoring that dermatology clinics are not built to manage and the risk-based restrictions payers attach to the JAK class. If the durability data hold up, that difference is the commercial case for the drug as much as the clinical one. Analysts split on the answer. Jefferies kept a buy rating and a $150 price target, calling the selloff unwarranted and arguing the findings do not change the drug's long-term prospects.
What the Phase 3 will have to prove
ZENITH-AA, the pivotal trial, will randomize about 850 patients, including adolescents and patients who have already taken a JAK inhibitor, to the 24 microgram dose or placebo, with 52 weeks of treatment and the share of patients at a SALT score of 20 or below as the primary endpoint. Nektar has said the study begins in early 2027. The population is broader than the Phase 2b's, which excluded prior JAK and biologic users, and it includes the patients who most need a second option.
The company's release also carried atopic dermatitis results from the same congress. In the REZOLVE-AD study, among patients re-randomized into the maintenance period, the share achieving complete skin clearance rose from 4 percent to 22 percent with monthly dosing and from 9 percent to 18 percent with quarterly dosing, and Nektar has started a third Phase 3 study in patients with prior biologic or JAK inhibitor experience. Off-treatment data for that program are expected in the first quarter of 2027.
What Vienna cannot settle is whether the durability signal is a property of the drug or of eight patients who happened to do well. The deepening pattern is the strongest argument for the first explanation, and it is also the smallest sample in the presentation. The pivotal trial reads its primary endpoint at week 52, while patients are still being dosed, so the off-treatment claim that animated the room in Vienna will not be settled by the endpoint that decides approval. Nektar has built its pipeline on the idea that a Treg drug behaves differently from everything approved for this disease. Eight patients cannot carry that idea on their own, and 850 will have to.
Primary sources
- Nektar Therapeutics, press release furnished with the October 1, 2026 Form 8-K, for the REZOLVE-AA and REZOLVE-AD results, the durability figures, the trial designs and the Phase 3 plans.
- Nektar Therapeutics, EADV investor presentation, for the off-treatment analyses, the 36-week cohort comparison, and the baricitinib cross-trial comparison with its statistical footnotes.
- ClinicalTrials.gov, REZOLVE-AA record, for the Phase 2b design, eligibility and enrollment.
- ClinicalTrials.gov, REZOLVE-AD record, for the atopic dermatitis study design.
- King et al., Baricitinib Withdrawal and Retreatment in Patients With Severe Alopecia Areata, JAMA Dermatology, 2024, for the relapse pattern after JAK inhibitor discontinuation.
- Investor's Business Daily, Nektar data coverage, October 1, 2026, for the share decline, the analyst safety critique and the pre-data run in the stock.
- MarketBeat, REZPEG data coverage, October 1, 2026, for the as-observed maintenance analysis, the dose selection, the safety summary and the Phase 3 enrollment details.
- GuruFocus, Jefferies note coverage, October 1, 2026, for the analyst defense and the price target.
- U.S. Food and Drug Administration, Litfulo approval letter, June 2023, for the JAK inhibitor approval and labeling context.
- National Alopecia Areata Foundation, alopecia areata overview, for the disease background and patient numbers.