Intra-arterial autologous myogenic stem cell therapy for m.3243A>G mutation carriers

Mitochondrial disorders are progressive, often fatal multisystem disorders, in
a part caused by mutations in the mitochondrial DNA (mtDNA). Epidemiological
studies have shown that mtDNA disorders affect about 1 in 10,000 of the general
population, inducing high health and societal costs and loss of quality of
life. Clinical manifestations most strongly affect organs with a high energy
demand, like muscle and brain. At this moment, there is no effective treatment
known to influence the disease process. Myogenic stem cell-based therapies
complementing defective muscle cells and fibres, are highly promising to combat
the myopathy and exercise intolerance which affect >50% of heteroplasmic mtDNA
mutation carriers. Myogenic stem cells called mesoangioblasts (MABs), are
currently the only myogenic precursors that fulfill all criteria to be used as
advanced therapy medicinal product for systemic treatment, namely good ex vivo
proliferation capacity, high myogenic capacity and a capability to cross blood
vessels, allowing intra-arterially (systemic) delivery towards affected muscle.
The only experience today is using allogeneic MABs transplantation in animal
models and patients with Duchene muscular dystrophy. Treatment with ex-vivo
expanded MABs resulted in significant regeneration of DMD positive muscle
fibers in the mice and dog models. Intra-arterial delivery of allogeneic MABs
in DMD boys (phase I/II clinical study) demonstrated that the treatment was
relatively safe and that dystrophin was being produced by the new muscle fibers
but insufficiently for clinical improvement. Our approach is superior as we use
autologous MABs, which do not required an immunosuppressive regime, and we need
only partial correction. We have demonstrated that MABs of most m.3243A>G
carriers contain no or only a low amount (<10%) of the mtDNA mutation, allowing
ex vivo expansion of patient-derived healthy MABs. The aim of this project is
to induce muscle regeneration using these autologous, healthy MABs, as an
autologous somatic cell therapy medicinal product (asCTMP).

In this phase I/II clinical study will assess the safety, effectiveness and
homing of asCTMP, namely autologous mesoangioblasts, that will be injected 3x
intra-arterially in right lower leg via catheter in 5 indivuals that carry the
m.3243A>G mutation.

Mono-center prospective open label intra-subject controlled phase I/II clinical
study.

A vastus lateralis muscle biopsy will be collected for isolation and ex vivo
expansion of mesoangioblasts. Intra-arterial administration of autologous
mesoangioblasts in right lower leg. Total dosis is 6*10E7/kg, which will be
administrated in 3 escalating dosis (1*10E7/kg, 2*10E7/kg and 3*10E7/kg) with
one month interval. Four weeks after last administration, skeletal muscle
biopsies in the tibialis anterior muscle of both legs will be collected.

All participants will visit the Erasmus MC five times.
- At the first visit, a routine clinical examination and eccentric exercise
training of the lower legs will be performed, a skeletal muscle sample (~200mg)
and blood sample (10 ml) will be collected.
- At the second visit, after a short eccentric exercise training of the lower
legs, 1*10E7/kg autologous mesoangioblasts will be intra-arterially injected in
right lower leg via catheter, followed by observation for 24 hours and 6 blood
samples (10ml) will be collected.
- At the third visit, 4 weeks after second visit, after a short eccentric
exercise training of the lower legs, 2*10E7/kg autologous mesoangioblasts will
be intra-arterially injected in right lower leg via catheter, followed by
observation for 24 hours and 6 blood samples (10ml) will be collected.
- At the fourth visit, 4 weeks after third visit, after a short eccentric
exercise training of the lower legs, 2*10E7/kg autologous mesoangioblasts will
be intra-arterially injected in right lower leg via catheter, followed by
observation for 24 hours and 6 blood samples (10ml) will be collected.
- At the fifth visit, after a short eccentric exercise training of the lower
legs and venous blood sampling, 3 muscle biopsies (30mg) of the tibialis
anterior in both legs will be collected

The burden and risk associated with participation will consist of the
collection of in total 7 skeletal muscle samples (1x 200 mg en 6x 30mg) and
injection of the asCTMP and buffer (procedure control). Muscle biopsies can be
painful in some cases. Infections and bleeding afterwards are possible, but
rare. To minimize patient burden, the six small (~30mg) muscle biopsies
collected at visit 5 will be collected using the Mag I automatic biopsy
instrument, which is a fast and routinely used procedure at the Erasmus MC to
harvest a small muscle fragment with patient burden being limited to the time
of the procedure (anecdotic information of multiple patients). No risks are
known to be associated with intra-arterial injection of autologous
mesoangioblasts. Autologous cells are not expected to trigger an immune
response. However, in the unexpected case that an immune response would occur,
this would result in inflammation that can be treated. Intra-arterial delivery
of allogeneic MABs was shown to be safe in children with DMD. Bleeding and/or
bruising at place of entry may occur.