A phase II trial of the DNA methyl transferase inhibitor, SGI-110 (Guadecitabine), in children and adults with SDH-deficient GIST, pheochromocytoma, and paraganglioma, and HLRCC-associated kidney cancer.

Abstract

11540 Background: Loss of activity of the Krebs cycle component succinate dehydrogenase (SDH) complex is a mechanism of tumorigenesis in SDH-deficient cancers. Accumulation of the metabolite succinate inhibits α-ketoglutarate-dependent dioxygenases leading to DNA hypermethylation. Guadecitabine is a small molecule DNA methyltransferase inhibitor. We conducted a Phase II study to test the hypothesis that guadecitabine will impact tumor growth by reversing DNA hypermethylation in tumors with Krebs cycle abnormalities (NCT03165721). Study Objectives: Our primary objective was to assess the clinical activity of guadecitabine in patients with SDH-deficient GIST, PHEO/PGL, and HLRCC-associated renal cell carcinoma. Secondarily, we desired to evaluate the toxicities of patients on treatment with guadecitabine. Methods: We conducted a single site, open label, phase II study using a small optimal two-stage design to evaluate response in SDH-deficient GIST, PHEO/PGL, and HLRCC-associated renal cell carcinoma. Patients >12 years of age received guadecitabine subcutaneously at 45mg/m2/day for 5 consecutive days on a 28-day cycle. Activity via imaging response was assessed utilizing RECISTv1.1. Toxicities were graded using version 4.0 of the NCI Common Toxicity Criteria. All patients were included in analysis. Results: We enrolled nine patients (6F:3M) with an age range of 18-57 years. Seven patients had SDH-deficient GIST (78%), one patient with paraganglioma (11%), and one with HLRCC-associated renal cell carcinoma (11%). No patients had a complete or partial response. Five patients came off study due to progression (56%) with one death due to disease progression in the patient with HLRCC-associated renal cell carcinoma (11%). Three patients (33%) withdrew due to lack of response with stable disease. One patient was withdrawn due to investigator’s discretion (11%). Toxicities possibly, probably, or definitely related to drug included grade 3 leukopenia (11%) febrile neutropenia (11%), grade 3-4 neutropenia (22%) requiring dose reductions, grade 3 hypertension (11%), grade 2 lung infection requiring hospitalization (11%). Conclusions: In this single site, open label, phase II study in patients with SDH-deficient GIST, PHEO/PGL, and HLRCC-associated renal cell cancer guadecitabine was tolerated by the majority of patients. No complete or partial responses were observed. Clinical trial information: NCT03165721 .