Ascletis says oral IL-17A pill rivals injectable biologics in psoriasis trial

Overview

Updated 1 hour ago

Psoriasis patients with moderate-to-severe disease have long relied on injected antibody drugs. Ascletis, a Hong Kong-listed biotech, says its experimental pill hits the same target without a needle. In a 28-day Phase I study of mild-to-moderate plaque psoriasis, once-daily 200 mg of ASC50 cut psoriasis area and severity index (PASI) scores by 48.9% over placebo.

ASC50 blocks IL-17A, the same protein targeted by injectable blockbusters like Novartis' secukinumab. The drug's 6.5-day half-life supports once-weekly dosing, and patients' PASI scores improved further for two weeks after the last dose. Larger trials will test whether that efficacy holds in a broader population.

Why it matters

If larger trials hold, psoriasis patients could swap regular antibody injections for a weekly pill, pressuring billions in IL-17 biologic sales.

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Key Indicators

48.9%

Placebo-adjusted PASI reduction at 28 days

Once-daily 200 mg ASC50 in mild-to-moderate plaque psoriasis.

65.9%

PASI reduction 15 days after final dose

Efficacy kept rising after dosing stopped, supporting once-weekly administration.

6.5 days

Steady-state elimination half-life

Long half-life underpins the potential for once-weekly oral dosing.

200 mg QD

Phase I once-daily dose

Dose tested across the 28-day proof-of-concept cohort.

Voices

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People Involved

Jinzi Jason Wu, Ph.D.

Founder, Chairman and CEO of Ascletis Pharma

Leading ASC50 development and pipeline strategy

Organizations Involved

Ascletis Pharma Inc.

Biotechnology company (HKEX: 1672)

Developer of ASC50 and other oral small-molecule drugs

Hong Kong-listed Chinese biotech developing oral small-molecule and peptide drugs for metabolic and inflammatory diseases.

Timeline

June 2025 September 2026

3 events Latest: Today

September 2026
Positive 28-day proof-of-concept results announced
Today Clinical results

Ascletis reports a 48.9% placebo-adjusted PASI reduction with once-daily 200 mg ASC50, a 6.5-day half-life, and no hepatic safety signal.
Today
June 2026
Phase I primary completion

The 94-participant study is recorded as complete as of June 2026 on ClinicalTrials.gov.
June 1st, 2026
June 2025
Phase I trial of ASC50 opens
Clinical trial

Ascletis launches a randomized, double-blind, placebo-controlled study enrolling healthy adults and mild-to-moderate plaque psoriasis patients (NCT07024602).
June 1st, 2025

Scenarios

ASC50 advances into Phase II trials

Likely Resolves by End of 2027

Discussed by: Ascletis management, citing the efficacy and safety profile as rationale to move the program forward

The 28-day results give a clear case for advancement: efficacy the company says is comparable to an approved biologic, a long half-life enabling weekly dosing, and no liver signal. If management prioritizes ASC50 over its metabolic pipeline, a larger trial could start within 12-24 months. The main variable is internal competition for resources with programs like ASC30.

Efficacy fades in a larger, broader trial

Possible Resolves by Q2 2028

Discussed by: Dermatology researchers watching oral-versus-biologic precedents such as apremilast, which underperformed biologics in head-to-head psoriasis trials

Phase I enrolled only mild-to-moderate patients for four weeks. A longer Phase II in more diverse, moderate-to-severe patients could erode the 48.9% placebo-adjusted reduction, and the mild adverse-event profile in a small cohort may not hold. A weaker readout would keep physicians prescribing biologic antibodies, which dominate moderate-to-severe disease.

Oral IL-17A inhibitors reach the market as a class

Uncertain Resolves by End of 2031

Discussed by: Industry observers tracking the broader conversion of injectable biologic franchises into oral drugs, from GLP-1 to JAK inhibitors

ASC50 or a competing oral small-molecule IL-17A inhibitor wins approval, opening a needle-free option for psoriasis and future autoimmune indications. This mirrors how oral JAK inhibitors carved out space beside TNF biologics. Multiple programs would need to sustain efficacy through Phase III, historically the stage where early oral drugs fail.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

November 2012

Tofacitinib (Xeljanz) approval (2012)

The FDA approved tofacitinib, the first oral JAK inhibitor, for rheumatoid arthritis. It gave patients a twice-daily pill instead of injected TNF blockers, though with a boxed warning for serious infections.

Then

Launched successfully and became a multibillion-dollar drug while competing head-to-head with biologics.

Now

Validated the model of oral small molecules rivaling biologic antibodies in autoimmune disease, even as later data added cardiovascular and malignancy warnings.

Why this matters now

ASC50 follows the same playbook: a pill aiming to displace an injected biologic franchise. Xeljanz proved the model works at market scale, and also showed safety scrutiny can catch up.

March 2014

Apremilast (Otezla) approval (2014)

The FDA approved apremilast, an oral PDE4 inhibitor for psoriasis and psoriatic arthritis. It offered a needle-free option with a clean safety profile, but only roughly a third of patients reached a 75% reduction in PASI score in pivotal trials, well below biologic response rates.

Then

Adopted as a safer, milder option, mostly for patients who don't want or need biologics.

Now

Established a key lesson for oral psoriasis drugs: efficacy, not convenience, determines whether a pill can displace an injectable.

Why this matters now

ASC50's 48.9% placebo-adjusted PASI reduction must be judged against biologic expectations, not just apremilast's bar. If a larger trial shows it slipping, the oral-psoriasis precedent suggests it will stay second-line.

January 2015

Secukinumab (Cosentyx) launch (2015)

The FDA approved secukinumab, the first IL-17A antibody, for moderate-to-severe plaque psoriasis. It quickly became a standard of care and one of the world's best-selling drugs, validating IL-17A as a commercial target.

Then

Rapid adoption drove blockbuster sales and spawned follow-on antibodies like ixekizumab and brodalumab.

Now

IL-17A blockade is now a cornerstone of psoriasis care and is expanding into ankylosing spondylitis and other inflammatory conditions.

Why this matters now

Secukinumab is the comparator Ascletis cites, and its sales are the prize an oral competitor would chase. The launch is proof that IL-17A is worth targeting.