GYM329 / Emugrobart (ROCHE) MANATEE Trial Results and Updates
GYM329 / Emugrobart (ROCHE) MANATEE Trial Results and Updates
Page last updated: 19th March 2026
Roche ends MANATEE Trials of emugrobart
Emugrobart – also known as GYM329 – was an investigational anti-myostatin antibody targeting muscle growth, in combination with EVRYSDI® (risdiplam).
Today Roche wrote to the SMA Community to say that they had made the difficult decision not to advance the drug into a Phase III development for SMA.
Roche reports that emugrobart did not consistently deliver the improvements they hoped for in muscle growth and motor function compared to treatment with risdiplam alone. The decision was not the result of any safety findings.
Roche recognises this news will be disappointing to the SMA community. They remain committed to advancing quality care for people living with SMA. They plan to share the data from MANATEE Part 1 at an upcoming medical conference so that this research can also help to inform the development of future treatments.
Roche’s Letter to the SMA Community >
Previous Updates:
July 2023
Trial sites in the UK:
| Manatee Trial of RO7204239 funded by Roche | ||
|---|---|---|
| All applicants must be currently receiving risdiplam or:-patients on nusinersen could shift and receive non-commercial risdiplam through the study.
-patients who have received zolgensma at least 90 days prior to starting the trial and are off all steroids, could enrol and receive non-commercial risdiplam through the study. Part 1 (recruiting now) -ambulant group -non-ambulant group Participants must be able to: -sit without support from arms while maintaining contact between their two hands for 5 seconds. -while seated, leaning forward to touch a tennis ball and sitting back again, either with or without support from the arms. -raise a standardized plastic cup with a 200g weight in it to the mouth, using both hands if necessary. Part 2 (not yet recruiting) -ambulant patients only |
25th January:
Trial Centres start to open in the UK.
22nd October:
Roche announced its intention of opening the Manatee trial in early 2022. This is a new global Phase 2/3 clinical study to evaluate the safety and efficacy of GYM329 (RO7204239) in combination with risdiplam. Part one will look at ambulant (able to walk independently) children with SMA aged 2-10 years, recently added to the study are non ambulant children aged 5-10 years. People previously treated with either risdiplam (Evrysdi), nusinersen (Spinraza), or onasemnogene abeparvovec (Zolgensma) are eligible, as well as those who have not received treatment before. There are also other eligibility criteria.
The MANATEE study consists of two parts:
Part 1 is a small study, with approximately 36 participants enrolled globally to assess the safety of two doses of GYM329 in combination with risdiplam. The aim is to be able to select the optimal dose of GYM329 for Part 2 of the study.
At this early stage of treatment development, the numbers are kept small as evidence of benefit or signals of risk is best achieved with small numbers of participants within a limited age range.
Part 2, the main part of the study, will assess the efficacy and safety of the GYM329 dose selected in Part 1 when combined with risdiplam. As this part of the study builds on the safety findings of Part 1 it will be able enrol more participants over a wider age range. It is expected to enrol approximately 144 participants globally. Part 2 will commence once the dose selection in Part 1 is complete.
Participants will be randomly assigned to either a treatment group that receives risdiplam and GYM329, or a treatment group that receives risdiplam and a placebo. All participants in the study will receive a daily dose of risdiplam at the approved dose throughout the study, including those in the placebo group.
Approximately 15 sites have been selected to participate in Part 1 of the study in countries including Belgium, Germany, Italy, Poland, the Netherlands, the UK and the USA. Enrolment for Part 1 started in early 2022 and is ongoing, Part 2 should start enrolling at the end of 2023. People who have an interest in joining the study should discuss treatment decisions with their physician.
Roche plan to explore the combination in other patient populations in the future, including a part 2 study for non-ambulant patients and in a broader age range.