Journal of Clinical Oncology | 2021
Benefits of pembrolizumab in progressive radioactive iodine refractory thyroid cancer: Results of the AcSé Pembrolizumab Study from Unicancer.
Abstract
6082 Background: AcSé Pembrolizumab is a Phase II, non-randomized parallel arm, open-label, multicentric study from Unicancer investigating the efficacy and safety of pembrolizumab monotherapy in different cohorts of patients with rare cancers (NCT03012620). Here we report the first results of pembrolizumab in the radioactive iodine refractory thyroid cancer cohort. Methods: Main inclusion criteria were progressive radioactive iodine refractory (RAIR) thyroid cancer (TC) resistant to standard treatment, age > 18, ECOG PS≤1. Patients received pembrolizumab 200 mg IV as a 30-minute infusion on Day 1 of every 21-day cycle for a maximum of 2 years. The primary endpoint was the confirmed objective response (OR) rate according to RECIST v1.1 by investigator. Secondary endpoints included duration of response, progression-free survival (PFS), overall survival (OS), and safety. Results: 43 patients (21 female, mean age 64.8 years; range 40-86) with TC (27 patients with differentiated TC (DTC) [papillary: 7; follicular: 14: oncocytic: 5 poorly differentiated: 1] and 16 patients with anaplastic TC (ATC)) were included from September 2017 to December 2020. The median number of previous systemic treatment lines was 2 (range, 0-7) in DTC and 2.5 (range, 1-4) in ATC. The median number of pembrolizumab cycles was 4 (range, 1-35). The median follow-up was 5.9 months (range: 22 days-22.9 months) for DTC and 2.7 months (range: 3 days- 24.4 months) for anaplastic TC. For DTC the best tumor response was partial response (PR) in 3 (11.1%) patients and stable disease (SD) in 5 (18.5%). Median duration of response was 2.5 months (range: 5 days-7.2 months). The median PFS was 2.6 months, the 6-month PFS was 16.9 %. The median OS was 12.7 months with a 6-month OS of 73.3%. For ATC the best tumor response was PR in 3 cases (18.8 %) and SD in 1 case (6.2 %). Median duration of response was 1.6 months (range: 2 days-7.2 months). The median PFS was 2.3 months, the 6-month PFS was 33.8 %. The median OS was 3.6 months with a 6-month OS of 32.9%. Treatment emergent adverse event included 9 Grade 1-2, 20 Grade 3 (3 being considered as related and 17 as not related) and 1 Grade 4 (sepsis, unrelated). Overall, the toxicity profile was similar to that observed in other cancers. Conclusions: The response rates observed under pembrolizumab is low in DTC and not negligible in ATC, but with a short duration of response. Clinical trial information: NCT03012620.