Personalising Aotearoa Lupus Medications: investigation of biomarkers for individualisation of therapy

SLE Patients Whole blood samples will be collected from SLE patients aged 18 years or older from the Auckland region who meet the inclusion and exclusion criteria and provide written informed consent. For any SLE patients receiving therapeutics (e.g., cyclophosphamide (CP), mycophenolate mofetil (MMF), azathioprine, prednisone, etc.) during the study period, these blood samples will be taken immediately prior to their next dose in order to maximise drug washout in the sample (CTROUGH). Blood samples will be collected at the University of Auckland Clinical Research Centre or appropriate Health New Zealand Te Whatu Ora facilities. Identifiable data will be stored separately to study data in a password-protected file on a secure University of Auckland study drive accessible only to the named study investigators. SLE patient demographics and medical history will be collected via a REDCap questionnaire prior to sample collection. For SLE patients, routine clinical data and treatment response and outcome data will be collected from patient records and entered into a secure REDCap database by the named study investigators. The follow-up period for collection of these data will be 6 months from the date of sample donation. An optional sub-study will also be available for SLE patients enrolled in the primary study who are receiving either CP or MMF (induction or maintenance) as part of their routine care. These patients will be asked to provide post-dose blood samples to assess the clinical sensitivity of the DNA damage (CP patients) and inosine-5'-monophosphate dehydrogenase (IMPDH) activity/polymerisation (MMF patients) assays. There will be no requirement for the sub-study samples to be collected on the same day as the primary sample collection. A limited sampling strategy (LSS) will be employed (1h, 2h, 4h), based on previous work in patients prescribed MMF to prevent acute graft-versus-host disease. The published LSS for CP is based on intravenous delivery, but as it includes two identical timepoints to the MMF LSS, we will utilise the same sampling timepoints for CP to reduce study complexity. For all primary study participants, up to 33 mL of blood (four tubes) will be collected, including at least one tube each of the PAXgene Blood DNA Tubes and the BD Vacutainer® CPT™ Mononuclear Cell Preparation Tubes (sodium citrate). An additional 24 mL of blood (three tubes) will be collected for SLE patients enrolled in the optional sub-study.