Final Report of the First Refractory Germ Cell Tumor Treated with Sunitinib Malate

Testicular choriocarcinoma: a rare variant that requires a unique treatment approach

Testicular germ cell tumors represent the most common malignancy among young men. While 5-year overall survival and cure for this population is greater than 95%, choriocarcinoma is an aggressive subtype of this disease with far worse prognosis--5-year survival for choriocarcinoma is less than 80%. In order to be able to treat these patients appropriately, a provider must recognize characteristic features of choriocarcinoma including elevated human chorionic gonadotropin in a young man with testicular mass; the astute clinician should also know the signs and symptoms of choriocarcinoma syndrome, characterized by bleeding from metastatic sites, which represents a medical emergency and is associated with high morbidity and mortality. Treatment should be directed towards a goal of tumor marker normalization, and patients with refractory disease should be considered for advanced therapies and clinical trials. Choriocarcinoma is a unique and aggressive germ cell malignancy, and these patients require early aggressive treatment to improve their chance of survival.

Next generation sequencing analysis of platinum refractory advanced germ cell tumor sensitive to Sunitinib (Sutent®) a VEGFR2/PDGFRβ/c-kit/ FLT3/RET/CSF1R inhibitor in a phase II trial

Background

Germ cell tumors (GCT) are the most common solid tumors in adolescent and young adult males (age 15 and 35 years) and remain one of the most curable of all solid malignancies. However a subset of patients will have tumors that are refractory to standard chemotherapy agents. The management of this refractory population remains challenging and approximately 400 patients continue to die every year of this refractory disease in the United States.

Methods

Given the preclinical evidence implicating vascular endothelial growth factor (VEGF) signaling in the biology of germ cell tumors, we hypothesized that the vascular endothelial growth factor receptor (VEGFR) inhibitor sunitinib (Sutent) may possess important clinical activity in the treatment of this refractory disease. We proposed a Phase II efficacy study of sunitinib in seminomatous and non-seminomatous metastatic GCT’s refractory to first line chemotherapy treatment (ClinicalTrials.gov Identifier: NCT00912912). Next generation targeted exome sequencing using HiSeq 2000 (Illumina Inc., San Diego, CA, USA) was performed on the tumor sample of the unusual responder.

Results

Five patients are enrolled into this Phase II study. Among them we report here the clinical course of a patient (Patient # 5) who had an exceptional response to sunitinib. Next generation sequencing to understand this patient’s response to sunitinib revealed RET amplification, EGFR and KRAS amplification as relevant aberrations. Oncoscan MIP array were employed to validate the copy number analysis that confirmed RET gene amplification.

Conclusion

Sunitinib conferred clinical benefit to this heavily pre-treated patient. Next generation sequencing of this ‘exceptional responder’ identified the first reported case of a RET amplification as a potential basis of sensitivity to sunitinib (VEGFR2/PDGFRβ/c-kit/ FLT3/RET/CSF1R inhibitor) in a patient with refractory germ cell tumor. Further characterization of GCT patients using biomarkers for clinical response and patient selection is warranted.

Trial registration

ClinicalTrials.gov Identifier: NCT00912912