Question to the Department of Health and Social Care:

To ask the Secretary of State for Health and Social Care, what information his Department holds on the potential thyroid cancer risk from Mounjaro; when his Department received this information; whether he has made an assessment of the potential impact of the provision of Mounjaro through the NHS on the risk of thyroid cancer; whether the Medicines and Healthcare products Regulatory Agency has requested information from the US Food and Drug Administration on its interim report on this matter of March 2024; and for what reason the risk-labelling for Mounjaro is different in the UK to that used in the US.

The Medicines and Healthcare products Regulatory Agency’s (MHRA) role is to continually monitor the safety of medicines during their use. We have robust, safety monitoring and surveillance systems in place for all healthcare products. New medicines such as Mounjaro, which contains tirzepatide, are more intensively monitored to ensure that any new safety issues are identified promptly.

Thyroid cancer has not been causally linked with Mounjaro or any other medicines that belong to the same therapeutic class as tirzepatide, specifically glucagon-like peptide-1 receptor agonists (GLP-1RAs), and it is currently not listed as a side-effect associated with GLP-1RA medicines in the approved United Kingdom prescribing information, also known as the Summary of Product Characteristics (SmPC).

A recent European Union review conducted by the European Medicines Agency (EMA) included a comprehensive class review of the available evidence related to all types of thyroid cancer, taking into consideration various types of evidence, including large observational studies, literature, clinical trial cases, and post-marketing cases. The EMA reached the decision that the overall evidence was insufficient to establish an association between GLP-1RAs and thyroid cancer. Furthermore, the addition of a precautionary warning to the SmPCs was not agreed upon given the limitations of the currently available evidence, unlike the Food and Drug Administration’s (FDA) approved product information. It is not uncommon for regulators to come to different decisions based on different assessments of risk. This can be due to factors such as differences in patient demographics, usage of a particular medicine in different countries, or differences in inclusion criteria for the product information for medicinal products. The difference in the United States’ labelling, in part, relates to the FDA’s interpretation of the data from animal studies, an area of research that is required for all new medicines prior to approval, and information related to thyroid cancer was added as a precautionary warning. However, the human relevance of the animal data is not known, and this is specified in the UK prescribing information.

A signal of thyroid cancer was not observed in the clinical trials for these medicines at the time of licensing, however it was acknowledged that clinical trials are not usually large or long-enough to observe cancer outcomes. Therefore, based on the need for further exploration of the risk about the human relevance, the pharmaceutical companies for all GLP-1RAs have been requested to assess the risk within a collaborative, long-term post-authorisation safety study evaluating medullary thyroid cancer events using United States cancer registries. The results from this study are not expected for a few years and will hopefully provide further information on this risk. Furthermore, the pharmaceutical companies are also monitoring all thyroid cancer types as part of their ongoing routine pharmacovigilance obligations.

Based on the current evidence, the benefits of GLP-1 RAs outweigh the potential risks when used for the licensed indications. The risk of thyroid cancer with this class of medicines remains under review by the MHRA and all pharmaceutical companies which hold a licence for a GLP-1RA. As part of our continuous monitoring procedures, we work with our international counterparts, such as the FDA, to gather information on the safety of medicines in other countries. When a safety issue is confirmed, we always act promptly to inform patients and healthcare professionals, and take appropriate steps to mitigate any identified risk.