CADTH Conducting Innovative Review of Treatment for Monkeypox

CADTH is undertaking an innovative review for an antiviral treatment to address the recent monkeypox outbreaks.

Monkeypox has become a serious public health issue around the globe. According to WHO, the most recent case fatality ratio from monkeypox infection is about 3% to 6%. The causes of death have been documented in high-risk groups such as infants, children less than 10 years old, those who are pregnant, patients with complications, and those who are immunocompromised.

In Canada, the Public Health Agency of Canada (PHAC) first announced 2 confirmed monkeypox cases in Quebec on May 19, 2022. As of June 22, 2022, there are 210 confirmed cases in Canada with 171 cases in Quebec, 33 cases in Ontario, 4 cases in Alberta, and 2 case in British Columbia. The number will likely continue to rise, and confirmed cases may be seen in other jurisdictions.

The PHAC National Emergency Strategic Stockpile (NESS) has a supply of vaccines and drugs in the event of a future smallpox emergency. The NESS stockpile includes the IMVAMUNE vaccine and TPOXX (tecovirimat) capsules, which would both be available to address the monkeypox outbreaks occurring in Canada. The National Advisory Committee on Immunization issued interim guidance on June 10, 2022, on the use of IMVAMUNE for postexposure prophylaxis in adults with high-risk exposure to a probable or confirmed case of monkeypox, or within a setting where transmission is happening.

In parallel, PHAC has requested that CADTH conduct a review to provide advice on the appropriate use of TPOXX (tecovirimat) for the treatment of monkeypox.

Throughout the COVID-19 pandemic, CADTH has conducted a number of abbreviated reviews. However, the review of TPOXX (tecovirimat) for monkeypox will be even more challenging given the lack of efficacy evidence within human clinical trials.

Much of the evidence to support the use of tecovirimat to treat monkey pox came from a development program based on animal studies under The Animal Rule, which states:

…the FDA may grant marketing approval based on adequate and well-controlled animal efficacy studies when the results of those studies establish that the drug is reasonably likely to produce clinical benefit in humans for drugs developed to ameliorate or prevent serious or life-threatening conditions caused by exposure to lethal or permanently disabling toxic substances, when human efficacy studies are not ethical and field trials are not feasible…

Our review of TPOXX (tecovirimat) for the treatment of monkeypox is a prime example of how CADTH is delivering on the Innovate pillar from our 2022-2025 Strategic Plan. We’re adopting a rigorous, transparent, and flexible approach to produce a fit-for-purpose report to meet our funders strict timelines and unique needs.

The review is anticipated to be completed in the summer of 2022 and will be published on CADTH.ca and in the Canadian Journal of Health Technologies.