Nektar's Rezpeg Faces a Durability Test as Off-Treatment Data Loom in Q1 2027
The Week 16 win already reported is now old news: REZOLVE-AD's next readout must show whether rezpegaldesleukin's effect holds 52 weeks after dosing stops, the question Phase 3 planning cannot answer alone.
Executive Summary
- Nektar Therapeutics will report topline data from the 52-week off-treatment period of the REZOLVE-AD Phase 2b trial in Q1 2027, testing whether rezpegaldesleukin's effect on atopic dermatitis persists after dosing stops Press ReleasePress ReleaseMar 12, 2026.
- The company already reported a Week 16 topline result in early 2026 describing reduced EASI scores versus placebo, but the underlying structured data mark that result as immature and the trial verdict as ambiguous, with no disclosed effect size or p-value Press ReleasePress ReleaseMar 12, 2026.
- Nektar has already committed to starting a Phase 3 program in atopic dermatitis before this durability data exist, which limits how much this specific readout can redirect the program Press ReleasePress ReleaseMar 12, 2026.
- The AppliedXL model assigns a 75.0% endpoint-met probability carried mainly by trial size, country count, and regulatory designation features rather than durability-specific evidence, with LOW confidence on that read.
- The trial's primary completion date has been revised twice and its protocol stability is labeled 'Unstable,' adding timing uncertainty around the stated Q1 2027 window.
The catalyst
Nektar Therapeutics is set to report topline data from the 52-week off-treatment period of its REZOLVE-AD Phase 2b trial (NCT06136741) in atopic dermatitis, with a stated window of January 1 to March 31, 2027 Press ReleasePress ReleaseMar 12, 2026. The trial enrolled 396 adults with moderate-to-severe disease, defined by an EASI score of 16 or higher, an IGA of 3 or 4, and body surface area involvement of 10% or more. Unlike a first efficacy test, this readout follows a Week 16 primary-endpoint disclosure already reported in early 2026, making the coming data a durability check rather than a first read on whether the drug works Press ReleasePress ReleaseMar 12, 2026.
Probability of SuccessBased on the AppliedXL Probability of Success model. For more information about the methodology, read the research here.
What the sponsor has said
Howard W. Robin, President and CEO of Nektar, called 2025 "a pivotal year for Nektar as we saw successful and transformative Phase 2 data readouts for rezpegaldesleukin," adding that the 52-week treatment data "provide hope that complete clearance of disease could be possible for patients with monthly and quarterly maintenance dosing" Press ReleasePress ReleaseMar 12, 2026. That framing is qualitative. The underlying structured result data available in the dossier list the primary endpoint result as "not_reported" as of the March 2026 event snapshot, flag the disclosure with a data-maturity tag of "immature_data," and characterize the overall trial verdict as "ambiguous". No EASI percent-change figure, p-value, or confidence interval for the Week 16 primary result appears in the dossier, and ClinicalTrials.gov has no posted results for this trial.
Already committed to Phase 3
Nektar says it plans to start its Phase 3 program in atopic dermatitis in the second quarter of 2026, months before the 52-week off-treatment data from this Phase 2b trial are due Press ReleasePress ReleaseMar 12, 2026. That timing means the sponsor has already made its go-forward decision based on the Week 16 data and whatever internal read it has of durability, not on the Q1 2027 readout itself. The upcoming disclosure will still matter for how the market and prescribers interpret the drug's dosing story, since the CEO has tied the durability question directly to maintenance-dosing frequency Press ReleasePress ReleaseMar 12, 2026.
Timing and protocol risk
The trial's primary completion date moved twice, from May 30, 2025 to June 1, 2025, then to May 6, 2025, and its protocol stability carries an 'Unstable' label based on registry change-event proxies, with 4.9 changes per year. Those are proxy signals, not confirmed protocol amendments, but they add uncertainty to whether the Q1 2027 window holds without further slippage.
Model basis and competitive frame
The AppliedXL model puts the probability of the endpoint being met at 75.0%, but confidence on that read is LOW, and the drivers behind it are dominated by structural features: enrollment per arm, number of countries, and FDA Fast Track designation, rather than any durability-specific clinical signal. No direct same-drug or same-target comparator exists in atopic dermatitis; the nearest IL-2 Receptor-targeted programs run in oncology settings such as melanoma and multiple myeloma, which are not comparable indications. Within atopic dermatitis itself, competing mechanisms include dupilumab, JAK1 inhibitors like upadacitinib and abrocitinib, and OX40L-targeted amlitelimab, none of which shares rezpegaldesleukin's regulatory T-cell expansion approach, so this readout offers limited direct competitive read-through beyond the sponsor's own pipeline.
This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.