Phase II study of everolimus and temozolomide as first-line treatment in metastatic high-grade gastroenteropancreatic neuroendocrine neoplasms.

BACKGROUND The optimal treatment for metastatic high-grade gastroenteropancreatic (GEP) neuroendocrine neoplasms when Ki-67 ≤55% is unknown. A prospective multi-centre phase 2 study was performed to evaluate the efficacy and safety of everolimus and temozolomide as first-line treatment for these patients. METHODS Patients received everolimus 10 mg daily continuously and temozolomide 150 mg/m2 for 7 days every 2 weeks. Endpoints included response, survival, safety and quality of life (QoL). Histopathological re-evaluation according to the 2019 WHO classification was performed. RESULTS For 37 eligible patients, the primary endpoint with 65% disease control rate (DCR) at 6 months (m) was reached. The response rate was 30%, the median progression-free survival (PFS) 10.2 months and the median overall survival (OS) 26.4 months. Considering 26 NET G3 patients, 6 months DCR was 77% vs. 22% among nine NEC patients (p = 0.006). PFS was superior for NET G3 vs. NEC (12.6 months vs. 3.4 months, Log-rank-test: p = 0.133, Breslow-test: p < 0.001). OS was significantly better for NET G3 (31.4 months vs. 7.8 months, p = 0.003). Grade 3 and 4 toxicities were reported in 43% and 38%. QoL remained stable during treatment. CONCLUSION Everolimus and temozolomide may be a treatment option for selected GEP-NET G3 patients including careful monitoring. Toxicity did not compromise QoL. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov (NTC02248012)

Germline pathogenic variants in patients with high-grade gastroenteropancreatic neuroendocrine neoplasms.

High-grade gastroenteropancreatic (HG-GEP) NEN are highly aggressive cancers. The molecular etiology of these tumors remains unclear and the prevalence of pathogenic germline variants in patients with HG-GEP-NEN is unknown. We assessed sequencing data of 360 cancer genes in normal tissue, from 240 patients with HG GEP-NEN; 198 patients with NEC and 42 with NET G3. Applying strict criteria, we identified pathogenic germline variants and compared the frequency with previously reported data from 33 different cancer types. We found a recurrent MYOC variant in 3 patients and a recurrent MUTYH variant in 2 patients, indicating that these genes may be important underlying risk factors for HG-GEP-NEN, when mutated. Further, germline variants were found in canonical tumor suppressor genes, such as TP53, RB1, BRIP1 and BAP1. Overall, we found that 4.5% of patients with NEC and 9.5% of patients with NET G3 carry germline pathogenic or highly likely pathogenic variants. Applying identical criteria for variant classification in-silico to mined data from 33 other cancer types, the median percentage of patients carrying pathogenic or highly likely pathogenic variants was 3.4% (range: 0-17%). The patients with NEC and pathogenic germline variants had a median overall survival of 9 months, similar to what is generally expected for metastatic GEP-NEC. A patient with NET G3 and pathogenic MUTYH variant had much shorter overall survival than expected. The fraction of HG GEP-NEN with germline pathogenic variants is relatively high, but still <10%, meaning that that germline mutations cannot be the major underlying cause of HG GEP-NEN