Following an initial report of three cases in 2022, a Canadian team has published the results of a retrospective study of 21 patients with severe and refractory Myasthenia Gravis with anti-MusK or anti-RACh, treated by autologous haematopoietic stem cell transplantation 1.9 to 21.8 years after diagnosis.
Out of 18 evaluable patients :
- 16 achieved and maintained the primary efficacy endpoint defined as clinically stable remission (no symptoms) or minimal manifestations status (MM-0) in the absence of treatment, which could be stopped within 0 to 5.6 years after transplantation,
- two improved, reaching MM-1 or MM-3 status under immunosuppressive and/or anticholinesterase treatment, but with fewer drugs than before the transplant.
The other three patients could not be assessed:
- one had cortisone myopathy,
- two died early due to transplant toxicity, giving a 100-day mortality rate of 9.5%.
However, the authors point out that the current mortality rate for all forms of myasthenia gravis is between 2.1% and 9%. For refractory forms of the disease, this rate could be little different from that observed in the Canadian study, due to the particular fragility of patients eligible for transplantation and the fact that it is carried out late, after many lines of treatment have failed.