Leprosy Mailing List – November 21, 2020
Ref.: (LML) Replacing opinions about leprosy treatment with research
From: David Scollard, Baton Rouge, Louisiana
Dear Pieter,
The thoughtful comments of Diana Lockwood and Steve Walker (LML Nov 8, 2020) and Gerson Penna (LML Nov 13 2020) regarding clinical evaluation of potential new leprosy treatment regimens are appreciated. However, they raise more questions.
1. What clinical criteria do the authors have in mind, other than relapse?
Relapse is one useful clinical measure but, as I detailed in the Viewpoint (Leprosy treatment: Can we replace opinions with research? PLoS Negl Trop Dis 14(10):e0008636. https://doi.org/10.1371/journal.pntd.0008636), it is a poor measure of the success of new leprosy treatment regimens for two main reasons. First, it is difficult to define; this currently depends on the slit skin smear, which has a host of its own technical problems. Second, relapse in leprosy occurs after many years. In addition to being a very slow means to validate a regimen, follow up for extended periods is expensive and labor intensive.
The slit skin smear and a requirement for a decade or more of follow up are not good foundations for 21st century medical research or practice. Where relapse can be assessed well it should be part of a robust trial, but depending solely on relapse to assess new regimens is not a wise path forward. Additional clinical criteria are needed if there is to be more emphasis on clinical evaluation in MDT trials.
2. What additional alternative regimens would the authors recommend? And importantly, how would they select the regimen?
Selection by an 'expert committee' has been the standard approach, but this continues the undesirable dependence on expert opinion. Selection based on empirical evidence of efficacy is much preferred. Methods that generate this evidence should be used, e.g., assessing several different regimens in small trials using the molecular viability assay to determine which regimen appears most efficacious in killing M. leprae in the human host.
3. Non-viability of the pathogen in a clinical specimen (i.e., failure to grow in culture) is an accepted measure of successful treatment in other bacterial infections. Why not for leprosy? The molecular viability assay now gives us a tool to measure the non-viability of M. leprae in MDT trials. We should use it.
Sincerely,
David Scollard
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
Contact: Dr Pieter Schreuder << editorlml@gmail.com
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