First clinical evidence for myocyte stem (satellite) cell targeting in DMD: Results from Part A of a Phase 1b/2 study of WVE-N531
Kuldeep Singh, BVSc, MS, PhD, Diplomate ACVP
Head of Pathology, Wave Life Science, Lexington, MA-02421, USA
May 19, 2024
Presented at MENA 2024
Disclosures
Kuldeep Singh, Laurent Servais, Craig Campbell, Michael Tillinger, Xiao Shelley Hu, Andrew Hart, Joseph A. Haegele, Jeanette Rheinhardt, Anamitra Ghosh, Fangjun Liu, Chandra Vargeese, Anne-MarieLi-Kwai-Cheung, Padma Narayanan
- Kuldeep Singh is a full-time employee of Wave Life Sciences
- Laurent Servais has provided consultancy and lectures, and attended advisory boards for Sarepta, Dyne, Pfizer, Santhera, RegenxBio, Affinia, and Fibrogen
- Craig Campbell has served as site investigator for Acceleron, AMO, Biogen, Dyne, Fibrogen, Pfizer, Roche, PTC, Sarepta, Cytokinetics, Ultragenix, and Wave and has acted as a Data Safety Monitoring Board member for Catabasis, Edgewise, and Solid. Additionally, he has received investigator-initiated grants from Genzyme, PTC Therapeutics, and Biogen
- All other authors are employees of Wave Life Sciences
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Overview
Phase 1b/2 Part A study design and results
WVE-N531 uptake in myogenic stem (satellite) cells
- Relevance of myogenic stem cell physiology and pathology in DMD
- Selection and protocol optimization of stem cell marker Paired Box Protein 7 (PAX-7) IHC and ISH
- Results and comments
Conclusions and next steps
Acknowledgements
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WVE-N531: An investigational phosphoryl guanidine (PN)-containing ASO being developed for patients with DMD amenable to exon 53 skipping
Phase 1b/2 (Part A): First-in-human study results
- High exon skipping and muscle concentrations after three doses administered at 10 mg/kg every other week
- Similar exon skipping regardless of mutation
- PK analysis indicated 25- day half-life in plasma
- WVE-N531appeared safe and well-tolerated
Patient | Tissue | Tissue | % Exon | Dystrophin |
concentration | skipping | by western blot | ||
Source | ||||
(ng/g) | by RT-PCR | (% of normal) | ||
1 | Deltoid | 85,500 | 61.5 | 0.24 |
2 | Deltoid | 33,500 | 49.8 | 0.23 |
3 | Bicep | 8,280 | 47.9 | 0.34 |
Mean muscle | Mean exon | Mean |
dystrophin: | ||
concentration: | skipping: | |
0.27% of | ||
42,400 ng/g | 53% | |
normal (BLQ) | ||
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Biopsies collected ~2 weeks post-last dose (3 biweekly doses of 10 mg/kg) | 42,400 ng/g = 6,120 nM | BLQ: Below level of quantification (1%) |
Data cut-off: December 6, 2022 |
Why assess stem cell uptake?
- Stem cells play a major role in muscle regeneration
- Lack of dystrophin in stem cells results in stem cell dysfunction and impaired regeneration
Normal Muscle | Dystrophic Muscle |
- Stem cells use dystrophin, Mark2, and Pard3 to maintain polarity that is needed to undergo asymmetric cells division as it results in maintenance of stem cell pool while giving rise to myogenic progenitors.
- In DMD, loss of dystrophin in stem cells result in impaired cell polarity, reduced asymmetric cells divisions, and thus reduced regeneration.
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Adapted from Keefe and Kardon, 2015
Experimental design: Myocyte stem cell uptake of WVE-N531
- The objective was to assess WVE-N531 uptake by skeletal muscle stem cells using biopsies from the 3 patients enrolled in Part A of the Phase 1b/2 study
- Rationale: Skeletal muscles of DMD patients show impaired differentiation and regeneration by stem cells due to lack of dystrophin.
- Hypothesis: WVE-N531 uptake by stem cells would restore stem cell differentiation and hence regeneration. For this part of analysis, the goal is to show WVE-N531 uptake in these cells
- Stem cell marker: Paired Box Protein 7 (PAX7)
- Assay: Dual PAX7 IHC and WVE-N531 RNAScope
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Kotters and Kischner 2010 and Ribeiro et al., 2019
Protocol optimization for PAX7 IHC: muscle from mdx mouse and healthy
human
Anti PAX7 Antibody - NBP232894
Sections stained with PAX7 antibody Sections stained with IgG antibody (control)
WVE-N531
Treated Mouse
Healthy human
(WVE-N531
untreated)
WVE-N531
Treated Mouse
Healthy human
(WVE-N531
untreated)
Note multiple PAX7 positive stem cells confirming specificity. Yellow arrows point to some of the positive nuclei.
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Background cytoplasmic signal in connective tissue and blood vessels.
Results: Observation of stem cells in patient samples
Patient No. 1 Deltoid Muscle | Location of Stem Cells in Myofibers | |||||
PAX7 Positive Stem Cells (Arrows)
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Background cytoplasmic signal in endothelial and smooth muscle cells.
Results: Observation of stem cells in patient samples
Patient 1
*
Patient 3
* *
Note degenerating myofibers (asterisks) and PAX7 positive nuclei (arrowheads) surrounding these myofibers
PAX7 and RNAScope dualplex without probe
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Controls: IgG for Pax7 - Negative, RNAScope Ubiquitin - Positive, & RNAScope DapB - Negative
Original mag: 20x and 40x
WVE-N531 demonstrated clear uptake in myogenic stem cells
Patient 1 | Patient 2 | Patient 3 |
Red signal: WVE-N531
Brown signal: PAX7
Positive stem cells
PAX7 and RNAScope dualplex
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Controls: IgG for Pax7 - Negative, RNAScope Ubiquitin - Positive, & RNAScope DapB - Negative; Serial sections are not available; Original mag: 20x and 40x
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Wave Life Sciences Ltd. published this content on 24 May 2024 and is solely responsible for the information contained therein. Distributed by Public, unedited and unaltered, on 24 May 2024 21:48:04 UTC.