Muscle biopsy technical safety and quality using a self-contained, vacuum-assisted biopsy technique

Draft Guidance for Industry Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Related Dystrophinopathies - Developing Potential Treatments for the Entire Spectrum of Disease

Background

Duchenne muscular dystrophy (DMD) and related dystrophinopathies are neuromuscular conditions with great unmet medical needs that require the development of effective medical treatments.

Objective

To aid sponsors in clinical development of drugs and therapeutic biological products for treating DMD across the disease spectrum by integrating advancements, patient registries, natural history studies, and more into a comprehensive guidance.

Methods

This guidance emerged from collaboration between the FDA, the Duchenne community, and industry stakeholders. It entailed a structured approach, involving multiple committees and boards. From its inception in 2014, the guidance underwent revisions incorporating insights from gene therapy studies, cardiac function research, and innovative clinical trial designs.

Results

The guidance provides a deeper understanding of DMD and its variants, focusing on patient engagement, diagnostic criteria, natural history, biomarkers, and clinical trials. It underscores patient-focused drug development, the significance of dystrophin as a biomarker, and the pivotal role of magnetic resonance imaging in assessing disease progression. Additionally, the guidance addresses cardiomyopathy's prominence in DMD and the burgeoning field of gene therapy.

Conclusions

The updated guidance offers a comprehensive understanding of DMD, emphasizing patient-centric approaches, innovative trial designs, and the importance of biomarkers. The focus on cardiomyopathy and gene therapy signifies the evolving realm of DMD research. It acts as a crucial roadmap for sponsors, potentially leading to improved treatments for DMD.

Retrospective comparison of ultrasound guided percutaneous and open skeletal muscle biopsies

BACKGROUND

Open skeletal muscle biopsy has been the mainstay of sample retrieval in patients with suspected muscle diseases. However, this technique is limited by surgeon and theatre availability, potentially resulting in delayed diagnosis and increasing hospital stay.

AIMS

To compare the effectiveness and timeliness of ultrasound guided 14-gauge needle percutaneous muscle biopsy in comparison with open biopsy.

METHODS

We performed a retrospective chart review on 19 inpatients who underwent ultrasound-guided percutaneous muscle biopsy using a 14-gauge needle and 19 consecutive inpatients who underwent open surgical muscle biopsy between January 2017 and June 2019. Patient demographics, length of stay, biopsy sample size and the correlation between histological and clinical diagnosis were compared between groups.

RESULTS

The median age of both groups was 64 years. Seventy-nine percent of surgical patients were female compared with 58% who had percutaneous biopsy. Surgical biopsies yielded larger samples (median 864 mm3 vs 17 mm3 , P = 0.03). While there was no difference in the length of inpatient stay (median 8 days), patients who had percutaneous biopsy had a shorter referral to procedure time (median 3 days vs 5 days, P = 0.012). Eighty-four percent of patients underwent MRI prior to percutaneous muscle biopsy, whereas only 16% had imaging before surgical biopsy (P ≤ 0.001). Most surgical biopsies were performed on the quadriceps whereas a wide range of muscles were sampled using the percutaneous technique. Overall, the percutaneous muscle sample was non-diagnostic in five cases (26%) despite a clinical diagnosis of myopathy. By comparison, two surgically obtained samples (11%) were non-diagnostic.

CONCLUSION

Ultrasound guided percutaneous muscle biopsies were performed faster and a wider range of muscles were targeted. However, this technique yielded smaller samples, which were non-diagnostic in 26% of cases. Increasing the needle gauge or number of passes may improve the diagnostic yield of this technique.

Muscle biopsy practices in the evaluation of neuromuscular disease: A systematic literature review

AIMS

Muscle biopsy techniques range from needle muscle biopsy (NMB) and conchotome biopsy to open surgical biopsy. It is unknown whether specific biopsy techniques offer superior diagnostic yield or differ in procedural complication rates. Therefore, we aimed to compare the diagnostic utility of NMB, conchotome and open muscle biopsies in the assessment of neuromuscular disorders.

METHODS

A systematic literature review of the EMBASE and Medline (Ovid) databases was performed to identify original, full-length research articles that described the muscle biopsy technique used to diagnose neuromuscular disease in both adult and paediatric patient populations. Studies of any design, excluding case reports, were eligible for inclusion. Data pertaining to biopsy technique, biopsy yield and procedural complications were extracted.

RESULTS

Sixty-four studies reporting the yield of a specific muscle biopsy technique and, or procedural complications were identified. Open surgical biopsies provided a larger tissue sample than any type of percutaneous muscle biopsy. Where anaesthetic details were reported, general anaesthesia was required in 60% of studies that reported open surgical biopsies. Percutaneous biopsies were most commonly performed under local anaesthesia and despite the smaller tissue yield, moderate- to large-gauge needle and conchotome muscle biopsies had an equivalent diagnostic utility to that of open surgical muscle biopsy. All types of muscle biopsy procedures were well tolerated with few adverse events and no scarring complications were reported with percutaneous sampling.

CONCLUSIONS

When a histological diagnosis of myopathy is required, moderate- to large-gauge NMB and the conchotome technique appear to have an equivalent diagnostic yield to that of an open surgical biopsy.

Histological Assessment of Gene Therapy in the Canine DMD Model

Assessing histological changes is essential for characterizing muscle disease progression and for studying the response to therapies in Duchenne muscular dystrophy (DMD), an X-linked progressive muscle-wasting disease caused by the loss of the dystrophin protein. Canine models are by far the best-characterized large animal models for DMD. In this chapter, we describe methods for muscle tissue collection and storage, hematoxylin and eosin staining for studying general muscle morphology, and special staining protocols for evaluating fibrosis, calcification, and neuronal nitric oxide synthase (nNOS) activity. We also provide immunofluorescence staining protocols that are often used to characterize the expression and localization of dystrophin and components of the dystrophin-associated glycoprotein complex. Lastly, we presented immunohistochemical staining protocols that we use to assess muscle inflammation and immune responses.

The Skeletal Muscle Microbiopsy Method in Exercise and Sports Science Research: A Narrative and Methodological Review

BACKGROUND

The skeletal muscle microbiopsy protocol was introduced to the Exercise and Sports Science (ESS) research field in 1999 and has been used as a protocol to directly examine muscular structural and biochemical changes. There is much variation in the reporting of the microbiopsy protocol and its related pre-and post-procedure for participant care and sample collection. The purpose of this narrative and methodological review is to compare the microbiopsy to the traditional Bergström protocol used in the ESS field, identify and summarize all related microbiopsy protocols used in previous ESS studies and determine the most frequently used microbiopsy protocols aspects and associated pre- and post-biopsy procedures; METHODS: A review of literature up to January, 2022 was used following the PRISMA and Cochrane Methodological Review Guide to determine frequently used methods that may facilitate optimal and potential recommendations for muscle microbiopsy needle gauge (G), concentration or dose (% or mL) and administration of local anesthetic, co-axial/cannula introducer gauge (G), muscle depth (cm), muscle sample size collected (mg), passes to collect samples, time points of muscle sampling, and promotion of participant compliance and minimization of adverse events; RESULTS: 85 articles were selected based on the inclusionary requirements related to the ESS field or methodological considerations. The most frequently reported aspects in previous research to suggest the location of the vastus lateralis is the midpoint between the patella and the greater trochanter of the femur or 1/3 or 2/3 the distance from the patella to anterior superior iliac spine, 14 G biopsy needle, subcutaneous injected lidocaine administration (2 mL; 1%), 13 G co-axial/cannula, 1-2 cm muscle depth, 10-20 mg of muscle sample, ~3-time points, 2-3 passes; DISCUSSION: There is much variation in the reporting of the microbiopsy protocol and its related pre-and post-biopsy procedures. Standardization in reporting may promote recommendations to optimize data integrity, participant safety, participant adherence to the study design, and increase reproducibility. Recommendations are made for the microbiopsy procedure based on frequently reported characteristics.

Recognition and Management of Neuromuscular Emergencies

Acute neuromuscular disorders represent an important subset of neurologic consultation requests in the inpatient setting. Although most neuromuscular disorders are subacute to chronic, hospital-based neurologists encounter neuromuscular disorders presenting with rapidly progressive or severe weakness affecting limb movement, respiratory, and bulbar function. Recalling fundamentals of neurologic localization assists in prompt recognition and diagnosis. Despite the differing localizations and the causal diagnoses, the initial management principles of acute myopathies, neuropathies, and neuromuscular junction disorders are similar.

Biomarkers in Glycogen Storage Diseases: An Update

Glycogen storage diseases (GSDs) are a group of 19 hereditary diseases caused by a lack of one or more enzymes involved in the synthesis or degradation of glycogen and are characterized by deposits or abnormal types of glycogen in tissues. Their frequency is very low and they are considered rare diseases. Except for X-linked type IX, the different types are inherited in an autosomal recessive pattern. In this study we reviewed the literature from 1977 to 2020 concerning GSDs, biomarkers, and metabolic imbalances in the symptoms of some GSDs. Most of the reported studies were performed with very few patients. Classification of emerging biomarkers between different types of diseases (hepatics GSDs, McArdle and PDs and other possible biomarkers) was done for better understanding. Calprotectin for hepatics GSDs and urinary glucose tetrasaccharide for Pompe disease have been approved for clinical use, and most of the markers mentioned in this review only need clinical validation, as a final step for their routine use. Most of the possible biomarkers are implied in hepatocellular adenomas, cardiomyopathies, in malfunction of skeletal muscle, in growth retardation, neutropenia, osteopenia and bowel inflammation. However, a few markers have lost interest due to a great variability of results, which is the case of biotinidase, actin alpha 2, smooth muscle, aorta and fibroblast growth factor receptor 4. This is the first review published on emerging biomarkers with a potential application to GSDs.

A well-tolerated core needle muscle biopsy process suitable for children and adults

Serial muscle biopsies within clinical trials for Duchenne muscular dystrophy (DMD) are critical to document therapeutic responses. Less invasive means of sampling muscle are needed. We analyzed a retrospective consecutive case-series cohort of vacuum-assisted core needle muscle biopsy procedures performed on healthy and dystrophic individuals at a single institution assessing for safety and reliability of obtaining sufficient high-quality biopsy tissue for histologic assessment in adult and pediatric subjects. Of 471 muscle cores from 128 biopsy procedures, 377-550 mg of total muscle tissue was obtained per procedure with mean core weight of 129 mg (SD, 25.1 mg). All biopsies were adequate for histological assessment. There were no significant adverse events. This core needle biopsy approach, when combined with improved sample processing, provides a safe means to consistently obtain muscle samples for diagnostic and clinical trial applications.

Total-body PET Imaging: A New Frontier for the Assessment of Metabolic Disease and Obesity

Obesity and associated metabolic syndrome are a global public health issue. Understanding the pathophysiology of this systemic disease is of critical importance for the development of future therapeutic interventions to improve clinical outcomes. The multiorgan nature of the pathophysiology of obesity presents a unique challenge. Total-body PET imaging, either static or dynamic, provides a vital set of tools to study organ crosstalk. The visualization and quantification of tissue metabolic kinetics with total-body PET in health and disease provides essential information to better understand disease physiology and potentially develop diagnostic and therapeutic modalities.

Enhanced Methods for Needle Biopsy and Cryopreservation of Skeletal Muscle in Older Adults

Human muscle biopsies are increasingly important for diagnosis, research, and to monitor therapeutic trials. We examined the use of a self-contained, vacuum-assisted biopsy system and a novel muscle freezing technique to improve, simplify, and standardize human muscle biopsy collection and cryopreservation in older adults. The VACORA vacuum-assisted biopsy system was deployed in muscle biopsies of 12 individuals ranging in age from 57 to 80 years. This office-based approach was well tolerated as it is minimally invasive, uses only local anesthetic, and has a quick recovery. To maximize biopsy sample quality and reproducibility, we developed a novel muscle sample freezing protocol. Fresh muscle biopsy samples were placed into readily available tissue cassettes followed by direct freezing in liquid nitrogen. After this modified snap freezing protocol, frozen muscle samples were enrobed in embedding medium for cryosectioning. We examined the effect of this freezing approach in histological sections of rodent and human muscle samples. The VACORA Biopsy System provided as many as four skeletal muscle core samples from a single biopsy site. Biopsy samples from 12 older adults weighed an average of 147.5 ± 11 mg each and had a consistent size and shape. There were no complications, and the residual scar is less than 10 mm. The freezing method using standard tissue cassettes with direct freezing in liquid nitrogen yielded high quality cryopreserved muscle tissue suitable for histological analysis without the need for isopentane and with little to no freeze-thaw damage. These enhancements have streamlined and improved the consistency of our muscle biopsy protocol and provide sufficient high-quality sample for multi-dimensional downstream studies of human muscle in aging and disease.