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Sirolimus use in inborn errors of immunity (IEIs)

There is currently no national consensus on the prescribing, monitoring or therapeutic drug monitoring (TDM) of sirolimus for patients with inborn errors of immunity (IEIs). Practice varies widely between centres, with different dosing strategies, monitoring frequencies, target trough levels and supporting evidence bases. Because IEI is a rare and heterogeneous group of conditions, individual clinicians and centres often rely on local practice, extrapolated evidence, or experience‑based decision‑making.


This survey aims to understand the current landscape of clinical practice across the UK and will help identify:
- Areas of variation in dosing and monitoring
- Common clinical indications
- Current target trough levels
- Existing local, national or international guidance/practices being used for all indications (for references)
- Gaps, challenges and unmet needs
- Additional therapies where clinicians feel national guidance is required
This information will ensure that the forthcoming guideline is grounded in real‑world practice, reflects the needs of the clinical community, and addresses areas of inconsistency or uncertainty.


The data collected will be analysed to:

- Map current national practice across immunology centres
- Identify areas of agreement that may inform suggested standards of care
- Highlight significant variation where evidence review and consensus‑building are needed
- Inform the structure, scope and recommendations of the national sirolimus guideline

Individual Trust‑level responses will not be identifiable in any published outputs. Findings will be summarised to support the guideline recommendations and inform the guideline indirectly.
1.Which Trust are you based at?
2.Is there an immunology service at your centre?
3.Are you currently managing patients with inborn errors of immunity (IEI) who are prescribed sirolimus?
4.If yes, approximately how many?
5.What are the clinical indications for sirolimus use in your patients and what target trough levels do you aim for?
6.What sirolimus dose do you use for each indication? Include dose (mg/kg or mg/m2) and frequency (e.g. once a day)
7.What target levels do you aim for each indication?
8.How frequently do you check sirolimus levels during...
9.What additional monitoring do you perform in patients on sirolimus? (tick all that apply)
10.What guidance do you follow for prescribing and monitoring sirolimus?
11.Are there other immunomodulatory or targeted therapies for IEI where national guidance would be helpful?
12.Would you be interested in being involved in developing national guidance or future collaborative work in this area?
Thank you for your participation. Participants can follow the results and guideline progress via the BSI-CIPN website and newsletter. For more information visit www.immunology.org/clinical/bsi-cipn or contact us at cipn@immunology.org.