Background
* Loss of activity of the Krebs cycle components succinate dehydrogenase (SDH) complex or fumarate hydratase (FH), has been identified as a mechanism of tumorigenesis in subsets of gastrointestinal stromal tumor (GIST), pheochromocytoma and paraganglioma (PHEO/PGL), and renal cell carcinoma.
* Deoxyribonucleic acid (DNA) hypermethylation has been demonstrated in these cancers. Loss of activity of SDH or FH leads to accumulation of the metabolites succinate and fumarate, respectively. Succinate and fumarate act as inhibitors of a broad array of alpha-ketoglutarate dependent dioxygenases. The Ten-eleven Translocation (TET) family of alphaKG-dependent dioxygenase enzymes convert 5-methylcytosine to 5-hydroxymethylcytosine leading to DNA demethylation. Inhibition of these enzymes due to SDH and FH deficiency causes DNA hypermethylation and has been verified in preclinical models.
* Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor of the gastrointestinal tract, resistant to cytotoxic chemotherapy and radiation therapy. KIT and Platelet Derived Growth Factor Receptor Alpha (PDGFRA) mutations have been identified as tumor initiating events in 85% of adult patients with GIST and these tumors are responsive to the tyrosine kinase inhibitor, Imatinib. In pediatric patients, however, 85% of GISTs lack KIT and PDGFRA mutations (wild-type) and imatinib is not effective.
* Recent work in the Pediatric and Wild-Type (wt) GIST Clinic at the National Cancer Institute (NCI) led to the identification of succinate dehydrogenase (SDH) deficiency in approximately 90% of wildtype GIST.
* In addition to wild-type GIST, SDH deficiency is also present in 30% of pheochromocytoma and paraganglioma (PHEO/PGL) and a subset of renal carcinoma. Loss of succinate dehydrogenase complex iron sulfur subunit B (SDHB) protein expression is seen in PHEO/PGL and wtGIST either due to mutation in SDH subunit genes or hypermethylation of the SDHC promoter region.
* Mutations leading to loss of function of FH have been identified in PHEO/PGL as well as type II papillary renal cell carcinoma in patients with hereditary leiomyomatosis and renal cell cancer (HLRCC). An FH-deficient paraganglioma had DNA hypermethylation as demonstrated by array and immunohistochemistry showed increased 5hmC levels in paragangliomas and pheochromocytomas.
* SGI-110 is a small molecule derivative of decitabine that acts as a DNA methyltransferase (DNMT) inhibitor and is resistant to inactivation by cytidine deaminase, hence may thus have a more favorable pharmacokinetic profile compared to decitabine. Subcutaneously administered SGI-110 is gradually converted to decitabine resulting in prolonged exposure with a several fold increase in apparent T1/2 compared to intravenous decitabine. SGI-110 has been demonstrated in preclinical models to induce a dose-dependent decrease in global DNA methylation and up-regulate expression of specific genes including Melanoma-associated antigen 1 (MAGE-A1) and New York esophageal squamous cell carcinoma 1 (NY-ESO-1) through decreased methylation.
* We are proposing a phase II trial with SGI-110 in these SDH-deficient and fumarate hydratase (FH)-deficient tumors.
Objectives:
-To assess the clinical activity of SGI-110 in patients with wt-GIST, SDH-deficient PHEO/PGL, and HLRCC-associated renal cell carcinoma (RCC) using Response Evaluation Criteria in Solid Tumors (RECIST).
Eligibility:
* Adults and children (greater than or equal to 12 years of age) with wt-type GIST, SDH deficient PHEO/PGL, or HLRCC-associated RCC and measurable disease will be eligible.
* Newly diagnosed patients with PHEO/PGL or HLRCC-associated RCC with localized, resectable disease will not be eligible. Patients with PHEO/PGL or HLRCC-associated RCC with unresectable localized disease and/or metastatic disease will be eligible.
* Newly diagnosed patients with wt-GIST with completely resectable disease will not be eligible. Patients with wt-GIST with metastatic disease and/or residual or recurrent tumor following surgical debulking will be eligible
* Patients with wt-GIST or HLRCC-associated RCC who have not previously received systemic therapy are eligible as there are no standard chemotherapy regimens known to be effective for these cancers.
* Must have adequate performance status, may not be pregnant or breastfeeding, and must have adequate major organ function.
* No history of severe or uncontrolled inter-current illness including, but not limited to, ongoing or active infection, symptomatic cardiovascular or pulmonary disease will be excluded.
Design:
* This is a single site, open label, phase II study using a small optimal two-stage design to evaluate the clinical response in three groups of patients:
1. wild-type GIST (GIST without KIT or PDGFRA mutation)
2. PHEO/PGL in patients with germline SDH subunit mutation, or
3. RCC associated with HLRCC
* SGI-110 will be administered subcutaneously at 45mg/m\^2/day x 5 days on a 28-day cycle to the three groups of patients.
* SGI-110 activity will be assessed by imaging response of measurable disease using Response Evaluation Criteria in Solid Tumors (RECIST)v1.1, using computed tomography (CT), magnetic resonance imaging (MRI) and/or positron emission tomography (PET).
* Patients will be closely monitored for development of toxicity with regular physical examinations and laboratory evaluations. Toxicity will be graded using version 4.0 of the National Cancer Institute (NCI) Common Toxicity Criteria.
* SGI-110 related toxicities greater than or equal to grade 3 will be considered treatment limiting toxicities, unless they are reversible within 72 hours with supportive care. Following recovery from toxicity up to 2 dose reductions will be allowed.
* Initially 7 evaluable patients in each group (strata) will be enrolled and if 0 of the 7 have a response, then no further patients will be accrued in that strata. If 1 or more the first 7 (14.3% or more) have a response, then accrual would continue until a total of 21 patients have enrolled in that strata. If at least 3 responses (at least 14.3%) are observed among the 21 evaluable patients, the agent should be considered worthy of further testing in this disease.
* Enrolling 2 patients/month, it is estimated to require 3 years to complete accrual to a maximum of 70 patients, a maximum of 63 evaluable patients allowing for a small number (7) of inevaluable patients.
