On November 7, 2022, the UK’s Medicines and Healthcare Products Regulatory Agency (“MHRA”) updated its “Guidance on the licensing of biosimilar products” by expanding the criteria for achieving interchangeability between a biosimilar and reference medicinal product (“RP”). The UK’s Guidance now recognizes that “[o]nce authorised, a biosimilar product is considered to be interchangeable with their RP, which means a prescriber can choose the biosimilar medicine over the RP (or vice versa) and expect to achieve the same therapeutic effect. Likewise, a biosimilar product is considered to be interchangeable with another biosimilar to the same RP.” The Guidance further explains that “[a]s a result of interchangeability, switching patients from one product to another (RP or biosimilar) has become clinical practice.”