Endocrine Abstracts

Introduction: Treatment of differentiated thyroid carcinoma (DTC) remains a challenge in the setting of locally advanced or metastatic disease refractory to radiodine (RAI) therapy. SELECT trial demonstrated that Lenvatinib improved progression free survival (PFS) comparing to placebo.

Objective: Our aim is to report the efficacy and safety of lenvatinib in our population with aggressive DTC.

Methods: We retrospectively reviewed the clinical records of 25 patients with advanced well-DTC who started treatment with lenvatinib in our center between january 2016 and january 2022. Patients with poorly differentiated or anaplastic thyroid carcinomas were excluded. Response evaluation was made according to the RECIST version 1.1 criteria. PFS and median overall survival (OS), best overall response (BOR), disease-control rate (DCR), response rate (RR) and clinical benefit rate (CBR) were also evaluated as efficacy measures. Additionally, the change of the sum of target lesion’s greatest diameters from baseline to nadir and tumor volume doubling times (TVDT) before and after therapy were also calculated.

Results: A total of 25 patients with well-DTC treated with lenvatinib were analyzed. Mean age at the initiation of treatment was 67.6±1.8 and 64% of patients were female. Twenty-four (96%) had metastasis (M1): 91.7% in the lung; 62.5% in bone and 62.5% of patients had M1 in ≥ 2 locations. Median duration of treatment with lenvatinib was 9.1 months and mean daily dose was 16.7 mg. The BOR was complete response in 1 patient (4%), partial response in 10 (40%), stable disease in 9 (36%) and progressive disease in 2 patients (12%). Response was not evaluable in 3 patients. RR was 44%; DCR 80% and CBR 68%. Median PFS was 25.6 (95% confidence interval (CI): 5.5-60.4) and OS was 29.6 (95% CI 25-34.1). The mean change of the sum of target lesion’s greatest diameters from baseline to nadir was -32.7% (±6.9). Median TVDT pre-lenvatinib was 10 months and median TVDT post-levantinib was -3.5 months. Our data showed that lenvatinib results in prolongation of TVDT in 86.7% of patients. AE were reported in 96% of patients, resulting in interruption and dose reduction in 68% and 52% respectively. The most frequent AE was hypertension in 85%. One patient had a grade 5 AE (rectum-vaginal fistulae with sepsis) and she had history of previous pelvic irradiation.

Discussion: Our results are in line with other real-life data and show that the clinical benefit can be obtained with lower doses. In addition, in our series lenvatinib showed an increased benefit in rapidly progressive disease. AE were frequent and serious AE related with wound healing may be potentiated by previous radiotherapy.