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RAPA-501

Bottom line

Small open-label studies suggest it is safe. A survival signal in advanced ALS rests on a comparison with computer-predicted patients, not a placebo group, so whether it helps is unknown.

RAPA-501 is a cell therapy made from a person's own T cells, which are reprogrammed in the lab into calming "regulatory" immune cells and given back by IV drip. It is in an open-label Phase 2/3 study at Massachusetts General Hospital, and an expanded access programme for people with advanced ALS has finished enrolling. No study has had a placebo group. Survival in the access programme was compared with computer-modelled patients, which is a weak comparison, and the results have not been published in a peer-reviewed journal.

Information checked 5 Nov 2026

Evidence: Early signal only

Studies: 2 mixed · 1 running

Only small, open-label or historical-comparison studies so far. Promising at best; not proof.

Unproven; survival vs computer-predicted patients only

26 of 34 (76.5%) alive at a median 8.9 months of follow-up, with no placebo group

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

At a glance

CompanyRapa TherapeuticsExplanation and sources

Rapa Therapeutics is a small private biotech in Rockville, Maryland that develops reprogrammed T-cell therapies. Its ALS work is run with the Healey & AMG Center for ALS at Massachusetts General Hospital, which also leads the NIH-funded expanded access programme. Rapa itself publishes very little news, so most updates come from MGH.

Sources

  1. First participant enrolled in RAPA-501 expanded access programMassachusetts General Hospital · 2 May 2024 · News
  2. Community Q&A webinar: RAPA-501 expanded access update (slides)Massachusetts General Hospital · 12 Feb 2026 · Conference presentation
How it worksYour own T cells reprogrammed to calm brain inflammationHybrid regulatory T cells (Treg/Th2)Explanation and sources

Inflammation in the brain and spinal cord is thought to speed up ALS. RAPA-501 is made by collecting a person's T cells and treating them in the lab so they become regulatory cells that dampen inflammation. They are then infused back into the same person.

Sources

  1. First participant enrolled in RAPA-501 expanded access programMassachusetts General Hospital · 2 May 2024 · News
  2. NEALS 2025 annual meeting abstracts (RAPA-501 expanded access)Muscle & Nerve · Conference presentation
StagePhase 2/3Open-label Phase 2/3 cohort recruiting at MGHExplanation and sources

The registry lists the trial as Phase 2/3, but the current part is a single-group study in which everyone gets RAPA-501 and the main goals are safety and whether treatment is feasible. It started in January 2025 and expects its main results around July 2027. It is not a large placebo-controlled trial.

Sources

  1. RAPA-501 therapy for ALS (NCT04220190)ClinicalTrials.gov · Trial registry
Best reported effectUnproven; survival vs computer-predicted patients only26 of 34 (76.5%) alive at a median 8.9 months of follow-up, with no placebo groupExplanation and sources

In the expanded access programme for advanced ALS, 26 of 34 treated people (76.5%) were alive at a median follow-up of 8.9 months. MGH reported this was better than expected from computer-modelled "virtual" control patients (p=0.01). Such predictions cannot account for every way the treated people differed from typical patients, and there was no placebo group. The earlier Phase 1 study in 9 people was about safety. None of this is published in a peer-reviewed paper yet.

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

Sources

  1. Community Q&A webinar: RAPA-501 expanded access update (slides)Massachusetts General Hospital · 12 Feb 2026 · Conference presentation
  2. NEALS 2025 annual meeting abstracts (RAPA-501 expanded access)Muscle & Nerve · Conference presentation
  3. RAPA-501MND Association · 21 Aug 2024 · Patient organisation
Who it's forTrial for earlier-stage ALS; access programme was for advanced ALSAll ALS · IV infusion of own reprogrammed T cellsExplanation and sources

The trial is for "standard-risk" ALS: symptoms for 24 months or less, breathing (slow vital capacity) at least 70% and ALSFRS-R between 34 and 45. The expanded access programme was for people with advanced ALS whose breathing was below 50%, who could not join trials.

Sources

  1. RAPA-501 therapy for ALS (NCT04220190)ClinicalTrials.gov · Trial registry
  2. Expanded access to RAPA-501 for advanced ALS (NCT06169176)ClinicalTrials.gov · Trial registry
What's nextPhase 2/3 trial main results (registry estimate)Expected July 2027Explanation and sources

ClinicalTrials.gov lists July 2027 as the estimated primary completion date; the company has not publicly promised a date. MGH also said it plans to analyse the access programme data and seek funding for a second access programme.

Sources

  1. RAPA-501 therapy for ALS (NCT04220190)ClinicalTrials.gov · Trial registry
  2. Community Q&A webinar: RAPA-501 expanded access update (slides)Massachusetts General Hospital · 12 Feb 2026 · Conference presentation
Can I join?Recruiting at MGH in Boston; access programme closed to new patientsRecruiting nowExplanation and sources

The Phase 2/3 trial is enrolling at one site, Massachusetts General Hospital. The expanded access programme for advanced ALS has finished enrolling and is listed as temporarily not available. Ask your clinic or the MGH Healey Center about eligibility.

Sources

  1. RAPA-501 therapy for ALS (NCT04220190)ClinicalTrials.gov · Trial registry
  2. Expanded access to RAPA-501 for advanced ALS (NCT06169176)ClinicalTrials.gov · Trial registry
  3. Expanded access programs at the Healey & AMG CenterMass General Brigham · Company website
  4. Actively recruiting ALS clinical trialsALS Therapy Development Institute · 30 Oct 2026 · Patient organisation

Signal: Silent

Signal measures how often, and how reliably, Rapa Therapeutics tells the public about this drug. It says nothing about whether the drug works. A quiet company isn't necessarily a bad sign, but regular, on-time updates help patients plan.

Last company updateNone found0 / 40
Company updates in the last 12 months00 / 35
Promises keptNot enough history yet (neutral score)12.5 / 25
Signal score13 / 100 · Silent

70 or more is Active, 45 or more is Steady, 20 or more is Quiet, below 20 is Silent. Full method.

Timeline

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

2026

  1. NewsALS Therapy Development Institute

    Trial still listed as recruiting

    ALS TDI's list of recruiting ALS trials, updated 30 October 2026, includes the RAPA-501 study at MGH.

  2. ConferenceNEALS

    Survival analysis presented at NEALS 2026

    An MGH investigator presented a propensity-matched analysis suggesting RAPA-501 may benefit people with advanced ALS. These are non-randomised comparisons.

  3. Trial registryClinicalTrials.gov

    Trial record updated; main results now expected July 2027

    The Phase 2/3 registry record was updated and lists an estimated primary completion date of July 2027, with the study still recruiting.

  4. ConferenceMassachusetts General Hospital

    MGH and Rapa share access programme results

    At a community webinar with Rapa's leaders, MGH reported that enrolment was complete and 26 of 34 treated people were alive at a median 8.9 months, which it said compared well with computer-modelled controls.

  5. Trial registryClinicalTrials.gov

    Access programme listed as temporarily not available

    The expanded access registry record was updated to show it is no longer taking new people.

2025

  1. Trial registryClinicalTrials.gov

    Phase 2/3 standard-risk cohort begins

    The registry lists January 2025 as the start of the open-label Phase 2/3 part of the study for people with earlier-stage ALS at MGH.

2024

  1. NewsMassachusetts General Hospital

    First person treated in the advanced-ALS access programme

    MGH and Rapa Therapeutics announced the first participant enrolled in the NIH-funded expanded access programme for people with advanced ALS.

All sources for this page

  1. RAPA-501 therapy for ALS (NCT04220190)ClinicalTrials.gov · Trial registry
  2. Expanded access to RAPA-501 for advanced ALS (NCT06169176)ClinicalTrials.gov · Trial registry
  3. First participant enrolled in RAPA-501 expanded access programMassachusetts General Hospital · 2 May 2024 · News
  4. Healey & AMG Center awarded NINDS grant for RAPA-501 expanded access programMassachusetts General Hospital · News
  5. Community Q&A webinar: RAPA-501 expanded access update (slides)Massachusetts General Hospital · 12 Feb 2026 · Conference presentation
  6. NEALS 2025 annual meeting abstracts (RAPA-501 expanded access)Muscle & Nerve · Conference presentation
  7. NEALS 2026 Annual Meeting agendaNEALS · Conference presentation
  8. Expanded access programs at the Healey & AMG CenterMass General Brigham · Company website
  9. RAPA-501MND Association · 21 Aug 2024 · Patient organisation
  10. Actively recruiting ALS clinical trialsALS Therapy Development Institute · 30 Oct 2026 · Patient organisation