MS 07.03 Novel Systemic Therapy for Carcinoid of the Lung

Abstract

Carcinoid tumors of the lung belong to a broad group of neoplasms called neuroendocrine tumors (NETs). These tumors are highly heterogeneous and represent a broad spectrum of phenotypes and clinical behavior. Often, the clinical behavior of these tumors corresponds with their underlying pathologic features. For example, in those tumors deemed as “typical carcinoid/NETs”, clinical behavior is often very indolent. At the other end of the spectrum, NETs can present as small cell lung cancer (SCLC) which is characterized by virulent and highly metastatic behavior. Those tumors deemed as “atypical carcinoid/NETs” usually have an intermediate clinical phenotype. Lung NETs are rare: the annual incidence rate is estimated to be approximately 1 in 100,000. In those patients whose lung NETs are no longer surgically resectable and/or have metastasized distantly, the treatment goals are principally disease control and symptom palliation. Because of their rarity, there are very limited prospective Level 1 data to guide optimal management of lung NETs. Treatment recommendations are often based on extrapolation from clinical experience in gastrointestinal NETs (especially pancreatic NET), subset analyses from other NET trials, anecdotal reports (case series), and expert opinion (e.g., consensus panels). Thus, the optimal management strategy for Lung NETs is not yet fully defined. Systemic therapy options range from somatostatin analog therapy, mTOR inhibitor therapy, and cytotoxic chemotherapy. Somatostatin analog therapy is offered in selected patient subsets that have slowly progressing disease and whose tumors express somatostatin receptors as detected by nuclear medicine scanning (Octreoscan). Somatostatin analog therapy is only modestly efficacious, with disease stabilization as the expected clinical benefit. Inhibition of the mTOR with everolimus has demonstrated efficacy in randomized trials. In the RADIANT-2 trial of everolimus+octreotide vs. placebo+octreotide in NETs, a small subset of patients with lung NETs (n=44) was analyzed. This showed an improvement in progression free survival with everolimus+octreotide vs. the control arm (median PFS8.8 months vs 2.8; Hazard Ratio (HR) = 0.62; p=0.1). Subsequently, the phase III RADIANT-4 trial of everolimus vs placebo in non-functional lung and GI NETs was conducted. In this trial, approximately 30% of the 302 randomized patients had lung NETs. RADIANT-4 showed a PFS and overall survival (OS) benefit in favor of everolimus (PFS HR=0.39, p<0.0001; OS HR=0.64, p=0.037). More recently, a randomized phase II trial (LUNA) of pasitreotide alone, everolimus alone, or the combination showed a trend for improved PFS for the combination arm (PFS at 9 months was 39.0% for pasitreotide alone, 33.3% for everolimus alone, and 58.5% for the combination). In patients who are not candidates for somatostatin analog therapy or everolimus, or have failed these therapies, cytotoxic chemotherapy is often considered. The most commonly used regimens include platinum-etoposide (similar to that employed for SCLC) and temozolomide. Response rates to chemotherapy are reportedly much lower in lung NETs (vs SCLC) in retrospective studies; for example, platinum-etoposide is reported to yield response rates of 20-30% in lung NETs compared to rates greater than 50% in SCLC. It is thought that tumor responses are possibly influenced by the degree of tumor de-differentiation. Other agents with anecdotal activity include 5FU, capecitabine, oxaliplatin, and anthracyclines. Prospective trials of systemic therapy in lung NETs are essential to define the optimal standards of care. 1. Hendifar, AE et al. J Thor Oncol 2016; 12(3):425-436 2. Yao, J. et al. Lancet 2016; 387: 968-77 3. Fazio N, et al. Chest 2013; 143(4):955-962. carcinoid, neuroendocrine tumors, NETs