A Phase II Study of the mTOR Inhibitor Sirolimus in Neurofibromatosis Type 1 Related Plexiform Neurofibromas

Brief Summary

Detailed Description

ABSTRACT/SCHEMA Sirolimus will be provided as oral solution 1 mg/ml to allow for precise dose adjustments. The tablet and oral solution forms are clinically equivalent (2003). Sirolimus will be administered orally twice daily (approximately every 12 hours) for a 28 day course with no rest period between courses. Sirolimus should be taken by the patient consistently either with or without food. Sirolimus should NOT be taken with grapefruit juice or with other effectors of CYP3A4 (see section 4.1.7). Dietary habits around the time of sirolimus intake should be as consistent as possible throughout the study, and in particular, during those periods when samples are being taken for pharmacokinetic analyses (if applicable). Limited exposure to sunlight and wearing sunscreen is recommended while taking this drug. If you miss a dose, treatment should continue without making up the missed dose. The starting dose will be 0.8 mg/m2 BSA per dose. Each patient's dose will be rounded to the nearest 0.1 mg (adult average 1.6 mg per dose). The BSA should be calculated based on an accurate height and weight measurement performed according to institutional guidelines, or using the following formula: Square root of: (Height\[cm\] X Weight\[kg\]/3,600) Dosing will be pharmacokinetically adjusted to maintain trough sirolimus levels within the target range of 10-15 ng/ml. (Appendix IV-A). The first sirolimus level will not be measured until week 2 to allow for loading to occur and to approach steady state concentrations. If patients are unable to achieve target trough sirolimus levels within 4 weeks, patients may be asked to have mini-pharmacokinetics of 3 blood draws, in addition to a trough level, in order to better estimate patient's dose. The extra trough sirolimus levels will be at: 1 hour, 3 hours, and 4-6 hours after a sirolimus dose. Sirolimus doses will be adjusted pharmacokinetically and will account for changes in body surface area. Dose modifications for patients who experience toxicities are outlined in Section 8.0. Sirolimus should be re-taken if vomiting occurs within 15 minutes of taking the dose, but not if vomiting occurs more than 15 minutes after taking sirolimus. Patients or their parents/guardians will keep a diary to document the intake of each dose of sirolimus and potential side effects. The patient diary should be reviewed with the patient's family at each required clinical study evaluation. In addition, leftover study medication should be collected at each on study evaluation, and drug should be accounted for at this time (Appendix V). A treatment course will consist of 4 weeks of therapy. For stratum 1 treatment may continue until disease progression or unacceptable toxicity occurs. Patients entered on stratum 2 may receive up to a maximum of 6 courses (i.e. 24 weeks) of therapy unless there is evidence of objective radiographic response, as defined in Section 13.0 (\> to 20% decrease in PN volume), tumor progression, or unacceptable toxicity. Patients who experience unacceptable toxicity or disease progression will be removed from treatment with sirolimus. Patients with documented radiographic response may continue treatment with sirolimus for up to 6 treatment courses after the maximum response. Background * Patients with Neurofibromatosis 1 (NF1) have an increased risk of developing tumors of the central and peripheral nervous system, including plexiform neurofibromas (PN), which are benign nerve sheath tumors that are among the most debilitating complications of NF1. Plexiform neurofibromas appear to have the fastest growth rate in young children. There are no standard treatment options for PN other than surgery, which is often difficult due to the extensive growth and invasion of surrounding tissues. * Mammalian Target of rapamycin (mTOR), a serine/threonine kinase regulated by the phosphoinositol 3 kinase (PI3K), acts as a master switch of cellular catabolism and anabolism and controls protein translation, angiogenesis, cell motility, and proliferation. * The NF1 tumor suppressor, neurofibromin, regulates the mTOR pathway activity, with increased mTOR activation observed in NF1-deficient cells and tumors from NF1 patients. * Sirolimus is a macrolide antibiotic that inhibits mTOR activity, preventing phosphorylation (and activation) of p70S6K, 4E-BP1, and other proteins involved in cell motility, angiogenesis, and cell growth control. Primary Objectives • To determine whether the mTOR inhibitor sirolimus, administered using pharmacokinetically-guided dosing: Increases time to disease progression based on volumetric MRI measurements in children and adults with neurofibromatosis type 1 (NF1) and progressive plexiform neurofibromas (PN). Results in objective radiographic responses based on volumetric MRI measurements in children and adults with NF1 and inoperable PN in the absence of documented radiographic progression at trial entry. * To evaluate the feasibility and toxicity of chronic sirolimus administration in this patient population. * To characterize the pharmacokinetic profile (profile includes pharmacodynamics and pharmacogenetics) of sirolimus when administered to this patient population. Eligibility * Patients ≥ 3 years old with NF1 AND * Inoperable, measurable, radiographically PROGRESSIVE PN that have the potential to cause significant morbidity. OR • Inoperable, measurable PN WITHOUT documented progression that have the potential to cause significant morbidity. Design * Sirolimus oral solution will be administered orally BID on a continuous dosing schedule (28 days = 1 treatment course) with pharmacokinetically-guided dosing. * Disease status will be evaluated using volumetric MRI analysis at regular intervals. * The plasma pharmacokinetics and pharmacodynamics of sirolimus will be evaluated, as will pharmacogenetic polymorphisms and their influence on the metabolism of sirolimus in this patient population. * Pain reduction and quality of life outcomes will also be assessed. * Toxicity of chronic sirolimus administered will be evaluated using physical and laboratory evaluations. EXPERIMENTAL DESIGN SCHEMA GOALS AND OBJECTIVES (SCIENTIFIC AIMS) Primary Aims To determine whether the mTOR inhibitor sirolimus, administered orally twice daily on a continuous dosing schedule (1 course = 28 days) using pharmacokinetically-guided dosing: Increases time to disease progression based on volumetric MRI measurements in children and young adults with neurofibromatosis type 1 (NF1) and inoperable progressive plexiform neurofibromas (PN), To evaluate the feasibility and toxicity of chronic sirolimus administration in this patient population. To characterize the pharmacokinetic profile of sirolimus when administered to this patient population. Secondary Aims To evaluate quality of life during treatment with sirolimus and to assess preliminary correlations of response with quality-of-life outcomes. To evaluate the effect of sirolimus on clinical response by reduction in pain, or improvement in function or performance scale.

Primary Outcomes

Secondary Outcomes

• To Evaluate the Quality of Life During Treatment With Sirolimus by Assessing Preliminary Correlations of Response With Quality-of-life Outcomes(24 weeks Stratum 1 / 48 weeks Stratum 2)
• To Assess the Value of Three-dimensional MRI (3-D MRI) in the Evaluation of Plexiform Neurofibromas and Paraspinal Neurofibromas, and to Compare 3-D MRI to Conventional Two-dimensional MRI (2-D MRI) and One Dimensional MRI (1-D MRI) Data Analysis(24 weeks Stratum 1 / 48 weeks Stratum 2)
• To Asses Preliminary Correlations of Radiographic Response With Changes in Pharmacodynamics Parameters Including p70s6 Kinase Activity in Peripheral Blood Mononuclear Cells.(24 weeks Stratum 1 / 48 weeks Stratum 2)
• To Evaluate the Effect of Sirolimus on Clinical Response by Reduction in Pain, or Improvement in Function or Performance Scale.(24 weeks Stratum 1 / 48 weeks Stratum 2)
• To Evaluate Pharmacogenetic Polymorphisms of Cytochrome P450 3A4 & 3A5 Alleles and P-glycoprotein/MDR for Their Influence on the Metabolism of Sirolimus in This Patient Population.(24 weeks Stratum 1 Only)
• To Evaluate the Role of Apolipoprotein E Genotypes as Predictors for Development of Hyperlipidemia During Therapy With Sirolimus.(24 weeks Stratum 1 / 48 weeks Stratum 2)