Somatostatin analogues in the management of thymic epithelial tumors: A retrospective, single-center study.

e20141 Background: Thymic epithelial tumors (TETs) are rare and heterogeneous entities, frequently coexisting with immune system dysregulation. Therapeutic decisions after disease progression on standard first-line platinum-based chemotherapy (CTx) can be challenging. Somatostatin analogues (SA) represent a treatment option, although their efficacy has not been exhaustively elucidated. Methods: We retrospectively collected data on the efficacy of SA administered with prednisone (SA-P) to consecutive patients with TET, referred to the Regional Coordination Center for Rare Tumors of Campania Region (CRCTR, Naples) between January 2004 and November 2023. Treatment eligibility was assessed using 68 Gallium PET-scan or OctreoScan, as per clinical practice. Progression-free survival (PFS) and overall survival (OS) were calculated from the start of SA-P treatment and estimated using the Kaplan-Meier method. Log-rank test was used to compare survival among patient groups according to platinum resistance (defined as disease progression occurring during or within 6 months from the end of platinum-based CTx), presence of autoimmune disorders (AD) or Good’s syndrome (GS) and histological subtype (thymoma vs. thymic carcinoma). Results: Overall, 32 patients were included in the analysis: 22 (68.75%) had thymoma,10 (31.25%) had thymic carcinoma. Thirteen patients (40.62%) had concomitant AD; 17 (53.12%) had GS. Eighteen patients (56.25%) were treated with SA-P immediately after progressing on platinum-based CTx; 6 (18.75%) received SA-P as a third or subsequent line of treatment, and 8 patients (25%) were treated with SA-P without previous platinum-based CTx, because of either ineligibility or patient and/or physician choice. Median PFS and OS were 22.5 and 49.5 months, respectively. Platinum sensitivity was associated with significantly longer PFS (57 vs. 17 months in patients with sensitivity vs. resistance to platinum, respectively; HR 0.26; p = 0.0021) and OS (median non-reached vs. 57 months in patients with sensitivity vs. resistance to platinum, respectively; HR 0.21; p = 0.0402). PFS was significantly longer in patients with AD than in those without AD (57 vs. 24 months; HR 0.36; p = 0.0085) and only numerically longer in patients with GS than in those without GS (54 vs. 33 months; HR 0.61; p = 0.3435). No significant difference in OS was observed according to the presence of AD or GS. No significant differences in PFS and OS were detected according to histological subtype. Conclusions: To our knowledge, this is one of the largest cohorts of patients with TET treated with SA-P. Our data suggest that platinum-sensitive disease and the presence of AD may potentially identify patients with higher chances to achieve sustained disease control with SA-P. Larger prospective studies are needed to confirm our data and to explore the molecular mechanisms of sensitivity/resistance to SA-P in TETs.