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Fosigotifator

Also known as ABBV-CLS-7262

Bottom line

In one large placebo-controlled trial it did not slow ALS. A higher dose hinted at slower loss of muscle strength, but that was an exploratory finding, and no ALS study is now running or planned.

Fosigotifator is a daily pill meant to switch off the cell's "stress response," which is stuck on in ALS and may stop motor neurons making the proteins they need. In the HEALEY ALS Platform Trial it did not slow ALS compared with placebo. Its ALS studies have ended, and its developer Calico is now pursuing it only for a rare childhood brain disease.

Information checked 5 Nov 2026

Evidence: Hints only

Studies: 1 mixed

Controlled trials missed their main goal. Some measures or subgroups looked better, which needs confirming.

How we decide the overall verdict: How to read this site.

At a glance

CompanyCalico Life SciencesExplanation and sources

Calico is a research company funded by Alphabet (Google's parent). It developed fosigotifator together with AbbVie, but AbbVie ended its partnership with Calico in November 2025. Calico continues to develop the drug for vanishing white matter disease, not ALS.

Sources

  1. AbbVie cuts ties with Calico, 100 scientists after 11-year partnershipFierce Biotech · 13 Nov 2025 · News
  2. Calico announces fosigotifator granted Breakthrough Therapy Designation for vanishing white matter diseaseCalico Life Sciences · 23 Jun 2026 · Company press release
How it worksPill that calms the cell stress response (eIF2B activator)eIF2B (integrated stress response)Explanation and sources

When cells are under stress they press a "brake" on making new proteins, called the integrated stress response. In ALS this brake may stay on too long and harm motor neurons. Fosigotifator activates a protein called eIF2B to release that brake.

Sources

  1. Calico statement on fosigotifator in HEALEY ALS Platform TrialCalico Life Sciences · 6 Jan 2025 · Company press release
  2. Fosigotifator fails to meet end points in HEALEY ALS Platform TrialNeurologyLive · News
StageDiscontinuedFailed HEALEY trial; no ALS studies ongoingExplanation and sources

Fosigotifator was tested as Regimen F of the HEALEY ALS Platform Trial (Phase 2/3), which missed its main goal in January 2025. A separate Phase 1 ALS study was ended early by the company in July 2025, and AbbVie left the Calico partnership that November. Calico has not announced any further ALS plans, so we list it as discontinued for ALS.

Sources

  1. Calico statement on fosigotifator in HEALEY ALS Platform TrialCalico Life Sciences · 6 Jan 2025 · Company press release
  2. Study of ABBV-CLS-7262 in participants with ALS (NCT04948645)ClinicalTrials.gov · Trial registry
  3. AbbVie cuts ties with Calico, 100 scientists after 11-year partnershipFierce Biotech · 13 Nov 2025 · News
  4. Fosigotifator (therapeutics database)Alzforum · News
What happenedMissed main goal in the HEALEY ALS trial; ALS studies ended and no ALS plans announced6 Jan 2025Explanation and sources

Calico announced the HEALEY results on 6 January 2025. Since then the remaining ALS study was terminated and the drug is being developed only for vanishing white matter disease, where the FDA gave it Breakthrough Therapy designation (June 2026) and Europe's EMA gave it PRIME support (October 2026).

Sources

  1. Calico statement on fosigotifator in HEALEY ALS Platform TrialCalico Life Sciences · 6 Jan 2025 · Company press release
  2. Study of ABBV-CLS-7262 in participants with ALS (NCT04948645)ClinicalTrials.gov · Trial registry
  3. Calico announces fosigotifator granted Breakthrough Therapy Designation for vanishing white matter diseaseCalico Life Sciences · 23 Jun 2026 · Company press release
  4. Calico announces EMA grants PRIME designation to fosigotifator for vanishing white matterCalico Life Sciences · 22 Oct 2026 · Company press release
Best reported effectNo benefit on main goal at 24 weeksALSFRS-R function score and survival, 24 weeksExplanation and sources

Among 310 participants, neither the main dose nor a higher exploratory dose slowed decline on the combined function-and-survival measure compared with placebo, and key secondary measures were also not different. In exploratory analyses at the higher dose, muscle strength declined more slowly (32% in the arms, 62% in the legs), but those numbers were not adjusted for multiple testing and could be chance. The drug was generally safe.

This is the most favourable result reported. See all key studies for the full picture.

Sources

  1. Calico statement on fosigotifator in HEALEY ALS Platform TrialCalico Life Sciences · 6 Jan 2025 · Company press release
  2. Topline results of AbbVie/Calico eIF2B activator fosigotifator in HEALEY ALS Platform TrialEUpALS · 9 Jan 2025 · Patient organisation
  3. ALS investigational therapies DNL343, fosigotifator fail HEALEY trial goalsALS News Today · News
Who it's forTested in people with any form of ALSAll ALS · Pill taken by mouthExplanation and sources

The HEALEY trial was open to people with sporadic or familial ALS. No subgroup was identified that clearly benefited.

Sources

  1. HEALEY ALS Platform Trial - Regimen F ABBV-CLS-7262 (NCT05740813)ClinicalTrials.gov · Trial registry
  2. Calico statement on fosigotifator in HEALEY ALS Platform TrialCalico Life Sciences · 6 Jan 2025 · Company press release
Can I join?No ALS trials or access programmesExplanation and sources

Both ALS studies of fosigotifator are over; the Phase 1 study was stopped early by the company. There is no way to get the drug for ALS now.

Sources

  1. HEALEY ALS Platform Trial - Regimen F ABBV-CLS-7262 (NCT05740813)ClinicalTrials.gov · Trial registry
  2. Study of ABBV-CLS-7262 in participants with ALS (NCT04948645)ClinicalTrials.gov · Trial registry

Timeline

6 events, newest first. Company updates are marked; independent news and regulator decisions are shown too.

2025

  1. NewsFierce Biotech

    AbbVie ends its 11-year partnership with Calico

    AbbVie, which co-developed fosigotifator, ended its research collaboration with Calico.

  2. Trial registryClinicalTrials.gov

    Phase 1 ALS study ended early

    The separate Phase 1 study of ABBV-CLS-7262 in ALS was terminated by the company after enrolling 31 people.

  3. NewsEUpALS

    European patient group summarises the negative HEALEY result

    EUpALS shared the HEALEY investigators' topline statement, including the exploratory muscle strength results at the higher dose.

  4. Press releaseFrom the companyCalico Life Sciences

    Calico reports that fosigotifator missed its main goal

    Fosigotifator did not slow ALS on the combined function-and-survival measure at either dose. Calico pointed to exploratory signals in muscle strength and said it would study the data further.

2024

  1. Trial registryClinicalTrials.gov

    HEALEY Regimen F finishes

    The registry lists this as the completion date of Regimen F, which enrolled 310 people.

2023

  1. Trial registryClinicalTrials.gov

    Fosigotifator starts in the HEALEY ALS Platform Trial

    Regimen F of the HEALEY platform trial began testing fosigotifator against placebo in people with ALS.

All sources for this page

  1. Calico statement on fosigotifator in HEALEY ALS Platform TrialCalico Life Sciences · 6 Jan 2025 · Company press release
  2. Calico announces fosigotifator granted Breakthrough Therapy Designation for vanishing white matter diseaseCalico Life Sciences · 23 Jun 2026 · Company press release
  3. Calico announces EMA grants PRIME designation to fosigotifator for vanishing white matterCalico Life Sciences · 22 Oct 2026 · Company press release
  4. HEALEY ALS Platform Trial - Regimen F ABBV-CLS-7262 (NCT05740813)ClinicalTrials.gov · Trial registry
  5. Study of ABBV-CLS-7262 in participants with ALS (NCT04948645)ClinicalTrials.gov · Trial registry
  6. Topline results of AbbVie/Calico eIF2B activator fosigotifator in HEALEY ALS Platform TrialEUpALS · 9 Jan 2025 · Patient organisation
  7. Fosigotifator fails to meet end points in HEALEY ALS Platform TrialNeurologyLive · News
  8. ALS investigational therapies DNL343, fosigotifator fail HEALEY trial goalsALS News Today · News
  9. AbbVie cuts ties with Calico, 100 scientists after 11-year partnershipFierce Biotech · 13 Nov 2025 · News
  10. Fosigotifator (therapeutics database)Alzforum · News
  11. Research update, April 2025ALS Canada · Patient organisation