[Current developments in the treatment of neuroendocrine tumors]. / Aktuelle Entwicklungen in der Behandlung neuroendokriner Tumoren.

BACKGROUND: Well-differentiated neuroendocrine tumors (NET) are rare malignancies that are clinically very heterogeneous. Accordingly, their treatment is also complex and dependent on various factors. With currently available systemic therapies, the prognosis is often favorable. OBJECTIVES: This article aims to provide an overview of current treatment strategies for NET, addressing the most important NET locations. METHODS: The current European guidelines and further relevant literature on the treatment of NET were reviewed for this purpose. RESULTS: The therapeutic spectrum for NET is extremely broad: For NET of the stomach/duodenum, appendix, and rectum, endoscopic or surgical resection is often sufficient, and metastatic tumors are rare. NET of the pancreas, small intestine and lung should also undergo potentially curative resection in the early stages. In the metastatic stage, locoregional treatments such as surgery and liver tumor embolization play a role. Major advances have been made in drug therapy, with somatostatin analogs (octreotide and lanreotide), an mTOR inhibitor (everolimus), and a tyrosine kinase inhibitor (sunitinib) being widely used. Peptide receptor radionuclide therapy (PRRT) is also an invaluable option. In some cases, classic chemotherapy is indicated. CONCLUSIONS: Many effective therapies are now available for NET. It is important to select the right therapy at the right time for each patient through interdisciplinary management.

From biology to clinical practice: antiproliferative effects of somatostatin analogs in neuroendocrine neoplasms.

Somatostatin analogs (SSA), specifically octreotide and lanreotide, have demonstrated antiproliferative effects in patients with neuroendocrine tumors (NET), a group of rare malignancies of diverse origin and presentation. A prominent feature of NET cells is the expression of G protein-coupled receptors called somatostatin receptors (SSTR). Although these SSTR are not uniformly present in NET, they can be instrumental in the diagnosis and treatment of NET. Apart from their application in nuclear imaging and radionuclide therapy, SSA have proven invaluable in the treatment of hormonal syndromes associated with certain NET (antisecretory effects of SSA), but it took more than two decades to convincingly demonstrate the antiproliferative effects of SSA in metastatic NET with the two pivotal studies PROMID and CLARINET. The current review summarizes three decades of SSA treatment and provides an overview of the clinical trial landscape for SSA monotherapy and combination therapy, including clinical implications and quality of life aspects, as well as ongoing fields of research.

Alternative schedule of temozolomide/capecitabine in neuroendocrine neoplasms.

The chemotherapy regimen capecitabine/temozolomide (CAPTEM) is routinely used in neuroendocrine tumors (NET), with antitumor activity particularly demonstrated in pancreatic or high-grade neuroendocrine neoplasms (NEN). However, different dosing regimens are used, and the optimal schedule remains to be defined. This single-center retrospective analysis assessed the efficacy and safety of CAPTEM in patients with NEN using a schedule starting both compounds simultaneously (temozolomide on days 1-5 and capecitabine on days 1-14 of a 28-day cycle) rather than sequentially. The primary parameters of interest were response rates, progression-free survival (PFS), and toxicities following this treatment regimen, hereinafter referred to as TEMCAP. The study population comprised 40 patients, half of whom (n = 20) had pancreatic NEN, and 9 patients (22.5%) had pulmonary or thymic NETs. The most common histology was NET G3 (n = 15, 37.5%), and 8 patients (20.0%) had a neuroendocrine carcinoma (NEC). Most patients (77.5%) had at least one prior systemic therapy, and 16 patients (40.0%) prior chemotherapy. The median number of TEMCAP cycles was 6 (range 1-16). Median PFS for the highly heterogeneous population was 13.3 months, while the median overall survival was 31.9 months. In total, 14/36 patients (38.9%) exhibited a partial response, and the disease control rate was 75.0%. The safety profile of TEMCAP (at a below-target mean temozolomide dose of 118.85 mg/m2) in our cohort was remarkably good with no toxicities of grade 3 or 4. Taken together, the results of this analysis further support the use of temozolomide/capecitabine in NEN and prompt further assessment of our modified TEMCAP schedule.

Does the dose matter? Antiproliferative efficacy and toxicity of everolimus in patients with neuroendocrine tumors - Experiences from a tertiary referral center.

The mTOR-inhibitor everolimus has been approved for the treatment of advanced neuroendocrine tumors (NETs) but is associated with relevant toxicities in clinical practice. Hence, optimal treatment sequencing and the impact of dose reductions have yet to be clarified. This retrospective analysis assessed patients with advanced, well-differentiated NET treated with everolimus at the Medical University of Vienna. The primary objective was to evaluate the efficacy of everolimus in a real-world cohort. A total of 52 patients treated with everolimus for advanced NET grade 1 (G1) or G2 (or typical or atypical carcinoid) 2010-2021 were included in this analysis. The most common sites of origin were pancreas (44%) and lung (29%). The initial dose was decided by the treating physician based on clinical assessment and 25 patients (48%) each were started at 10 mg/day and 5 mg/day. Median progression-free survival (PFS) following everolimus in the overall cohort was 9.8 months (95% CI: 4.3-15.3), with a statistically significant PFS difference (p = .03) between NET G1/typical carcinoids (42.9 months) and NET G2/atypical carcinoids (8.9 months). PFS was numerically but not significantly shorter in patients treated with a reduced dose (7.5 months vs. 12.4 months, p = .359). Even in this mixed full/half dose cohort, 93% developed treatment-related side effects (mostly grade I, no grade IV), 63% had dose reductions or interruptions, and five stopped due to toxicity. Median survival following treatment was 40.9 months (95% CI: 21.5-60.3) and no difference with regard to dosing was observed (p = .517). These data from an unselected patient cohort show long-term outcomes similar to those reported in the pivotal studies. Comparing everolimus starting dose, median PFS did not significantly differ for patients treated at a lower dose. While this finding is limited by the sample size and warrants prospective verification, initiating therapy at a reduced dose might be practicable and safe in a distinct subset of patients.

Treatment patterns and oncological outcome of patients with advanced small intestinal neuroendocrine tumors: real-world data from the Medical University of Vienna.

Background: Different oncological therapies have been approved for small intestinal neuroendocrine tumors (SI-NETs), but relatively little is known about efficacy and long-term outcome outside of phase III trials. Methods: This retrospective analysis assessed patients with well-differentiated, metastatic SI-NETs treated at the Medical University of Vienna, an approved European Neuroendocrine Tumor Society (ENETS) Center of Excellence for neuroendocrine tumors. The primary objective was to assess progression-free survival (PFS) following approved therapies, that is, octreotide, lanreotide, peptide receptor radionuclide therapy (PRRT), and everolimus, in a representative real-world collective. Results: A total of 77 patients receiving systemic treatment for advanced SI-NETs between 2010 and 2021 were included, with a median follow-up time of 82.3 months [95% confidence interval (CI), 57.8-106.8 months]. In the entire collective, the estimated median PFS following first-line therapy was 32.0 months (95% CI, 23.5-40.5 months). Peritoneal carcinomatosis was significantly associated with worse PFS (p = 0.016). Regarding therapeutic strategies and outcome, 59 patients received somatostatin analogs first line and no significant difference in PFS was observed between lanreotide and octreotide (29.3 versus 35.5 months, p = 0.768). Across all treatment lines, 42 patients underwent PRRT (estimated median PFS: 32.0 months; 95% CI, 25.6-38.3 months) and a small subgroup of 7 patients received everolimus (estimated median PFS: 9.2 months; 95% CI, 1.6-17.0 months). For the total cohort, the estimated median OS following first-line therapy was 100.6 months (95% CI, 82.3-118.8 months), but the high proportion of deaths attributed to NET (77.8%) underlines the lethal nature of the disease. No unexpected toxicities were observed. Conclusions: While peritoneal carcinomatosis emerged as an adverse prognostic factor for PFS in this collective, the long-term outcome of patients treated at a specialized NET center using approved therapies appeared comparable to pivotal studies in SI-NET.