Efficacy and Safety of Lanreotide Autogel and Temozolomide Combination Therapy in Progressive Thoracic Neuroendocrine Tumors (Carcinoid): Results from the Phase 2 ATLANT Study.

INTRODUCTION: Lanreotide autogel (LAN) and temozolomide (TMZ) are guidelines-recommended monotherapies for thoracic neuroendocrine tumors (carcinoids; T-NETs), but prospective data for both combined and monotherapies are lacking. ATLANT (NCT02698410) evaluated efficacy and safety of LAN/TMZ in progressive T-NETs. METHODS: ATLANT was a 12-month, Italian, phase 2, single-arm, open-label, multicenter pilot study. Eligible patients had unresectable, locally advanced/metastatic, well-/moderately differentiated T-NETs with radiological progression. Patients received subcutaneous LAN 120 mg every 28 days and oral TMZ 250 mg/day for 5 consecutive days every 28-day cycle. Main endpoints are disease control rate (DCR) at 9 months (primary; investigator-assessed), median progression-free survival (PFS), biomarkers, and safety. RESULTS: The number of patients was 40; 60% were male. Primary tumor site was lung (90%) and thymus (10%). Carcinoid type was typical (20.0%) and atypical (52.5%). DCR at 9 months was 35.0% (95% confidence interval (CI) 20.63-51.68; nonacceptability threshold ≤10%, p < 0.0001; not significantly above clinically relevant threshold ≥30%, p = 0.2968). DCR between 7.5 and 10.5 months (sensitivity analysis) was 45.0% (95% CI: 29.26-61.51) and clinically relevant (p = 0.0320 at ≥30% threshold). Median PFS was 37.1 (95% CI: 24.1-52.9) weeks. No association was observed between biomarker variations (chromogranin A, neuron-specific enolase, somatostatin receptor type-2, Ki-67, 6-O-methylguanine-DNA-methyl-transferase) and DCR or PFS. Most patients (97.5%) had treatment-emergent adverse events (TEAEs); 72.5% had treatment-related TEAEs. TEAEs were mainly grade 1/2. No unanticipated TEAEs were reported. CONCLUSIONS: This study showed that the LAN/TMZ combination has promising efficacy in progressive T-NETs, and was well tolerated. Larger studies are warranted to support the clinical benefits of LAN/TMZ in patients with T-NETs.

Differential interaction of Enigma protein with the two RET isoforms.

The receptor tyrosine kinase RET, with a known role in embryonic development and in human pathologies, is alternatively spliced to yield at least two functional isoforms, which differ only in their carboxyl terminal. Enigma protein is a member of the PDZ-LIM family and is known to interact with the short isoform of RET/PTC2, a chimeric oncoprotein isolated from papillary thyroid carcinoma. Here, we show that Enigma also interacts in intact cells with the short isoform of RET-wt and of its pathologic mutants associated to MEN2 syndromes, RET-C634R and RET-M918T. In contrast, Enigma binds all the corresponding RET long isoforms very poorly and colocalizes with short but not long RET/PTC2 isoforms. The RET docking tyrosine for Enigma is the last but one before the divergence between the two isoforms and we demonstrated that short-isoform-specific amino acid residues +2 to +4 to this tyrosine are required for the interaction of RET/PTC2 with Enigma.