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Important information about your medicine – denosumab (120mg) biosimilar switch

This webpage is for patients who are currently prescribed or have been prescribed a medicine called denosumab in the past year, under the care of the oncology department.

It is about an upcoming change to denosumab subcutaneous injections (injection under the skin) at King’s College Hospital NHS Foundation Trust.

From January 2026, we will be changing the brand of this medicine from Xgeva to Yaxwer (vials) or Bomyntra (prefilled syringes), which is known as a biosimilar medicine. This page provides more information about this change and what this means for you, if you are due to receive denosumab injections with King’s College Hospital Foundation Trust.

What is a biosimilar medicine?

A biosimilar is a highly similar version of an existing biological medicine (called an originator medicine or reference product). It is approved by the Medicines and Healthcare products Regulatory Agency (MHRA). Biosimilars match the originator medicine in terms of safety, quality, and effectiveness and have been widely used in the NHS for many years.

Why is this change happening?

This change is part of national and Trust-wide efforts to optimise the use of best value medicines. All medicines made by pharmaceutical companies have a patent that lasts many years. The patent means that only the company who developed the medicine is allowed to sell it. When patents expire, more pharmaceutical companies can manufacture and licence the medicine so there is more competition and a lower medication cost.

Cost savings can be substantial, and by switching to the biosimilar we are able to provide you with the same level of care whilst saving money that can be redirected to patient care within the NHS. This means that your biosimilar brand may be switched again in the future. We will tell you if your medicine is changing, either by an electronic letter on your MyChart app, a text message, an email, or a physical letter in the post. We have a lot of experience with switches at King’s College Hospital across multiple specialties.

Am I likely to experience side effects after switching?

As you have been on Xgeva previously, you are unlikely to experience any new or different side effects after switching to the biosimilar medicine. As always, your treatment will continue to be carefully monitored, if you do experience any side effects or have concerns, please contact your doctor or specialist nurse.

Do I need any additional tests before switching?

No additional tests are required specifically for the switch. You should continue with your routine monitoring, such as clinical examinations and scans, as advised by your clinical team.

What does this mean for you?

  • You may notice a different brand name or delivery device (for example, a pre-filled pen or syringe), but this does not affect how the medicine works.
  • You will continue to receive the same level of care and clinical monitoring.
  • The way the medicine works in your body will remain the same.

Further information and support

If you have questions or concerns regarding the switch, please contact us by phone or email using the details below and a member of the pharmacy team will phone you back at a suitable time:

Please provide the following details in your email or message:

  • full name
  • date of birth
  • NHS or hospital number
  • contact number
  • availability for a call back between 10am and 4pm, Monday to Friday

Please note this is a dedicated phone number and email address for biosimilar switches which will be open for a limited time between 16 February 2026 and 08 March 2026. Outside of this time please contact your prescribing team via your clinic.

We encourage all patients to sign up for the MyChart app to receive reminders for appointments and monitoring.

For further information, go to:

The Patients Association website – information on switching to biosimilar medicines

The oncology department are here to support you throughout this transition. Thank you for your continued cooperation.