What this trial measures

• Determine if glucosylceramide (GC) and lactosylceramide (LC) species levels correlate with tumor burden in patients with NF11 year

  The investigator and team will collect blood samples from individuals with NF1 stratified plexiform tumor (PNF) burden (none, small, intermediate, and large) versus age and sex matched healthy control.

• Test if tumor burden correlates with GC and LC signature in individuals with NF1 who are undergoing clinical treatment with MEK inhibitors1 year

  The investigator and team will enroll 20 individuals with NF1 and inoperable PNFs in treatment with MEK inhibitors to correlate biomarker with tumor burden changes with therapy.

• Assemble a longitudinal cohort of individuals with NF1 with plexiform neurofibromas (n=100) for deep phenotyping and tumor burden response to MEK inhibitors1 year

  Whole-body MRI at baseline and at time of annual visit (9-to-18-month intervals) will be used to deeply phenotype individuals based on tumor burden and tumor volume. Individuals will undergo plasma collection and clinical history assessment (medications, diet log, supplements, and anthropometric measurements) at each visit. For patients undergoing treatment with MEK inhibitors, a sample prior to treatment will be collected during this study.

• Determine if glucosylceramide (GC) and lactosylceramide (LC) signature correlates with plexiform neurofibroma burden change in longitudinal cohort of 100 individuals with PNFs1 year

  The investigator and team will test GC/LC levels using validated mass spectrometry target method for quantification of these biomarkers.

• Tumor volumetric analysis will be performed to correlate with GC/LC monitoring biomarker signature1 year

  GC/LC biomarker thresholds (cut-off) will be refined to evaluate predictive ability to identify individuals with large tumor burden. Tumor burden will be measured from whole-body MRI analysis with post-imaging processing software.