Replacement Dose for Overt Hypothyroidism Induced by Programmed Cell Death Protein 1 Antibodies May Be Higher than Recommended.

Abstract

The present recommendations, consensus, or guidelines for the replacement dosage for hypothyroidism induced by programmed cell death protein 1 (PD-1) therapy are not uniform, and there are very few special clinical trials that have examined the replacement dosage for it. This article illustrates the clinical characteristics of hypothyroidism induced by PD-1 antibodies (Abs) and reports the recommended replacement dosage for hypothyroidism. Eighteen patients with overt primary hypothyroidism induced by PD-1 Abs (group 1) were selected from 655 patients with different tumor types. Retrospective analysis was performed on patients in group 1 and 18 patients with natural courses of overt primary hypothyroidism who were age- and sex-matched with the patients in group 1 (group 2). The replacement dosages required for the patients in the two groups were compared. Thyroid dysfunction occurred in group 1 after approximately 3.0 ± 1.4 cycles of PD-1 therapy (1-6 stages), with a median time of 61.5 days. The median time of onset of hypothyroidism among all patients was 87.5 days (30-240 days). Most of the patients with hypothyroidism were asymptomatic, and the onset of hypothyroidism was independent of age, sex, TPOAb, TgAb and TSH in group 1 (P>0.05). The average replacement dosage for patients in group 1 was 1.8 ± 0.6 μg/kg/d (0.6-3.2 μg/kg/d). Multiple linear regression analysis showed that sex, age, TPOAb, TgAb and TSH were not correlated with drug dosage. It seemed that the average maintenance dosage of levothyroxine might need to be 1.8 μg/kg/day for patients with overt hypothyroidism induced by PD-1 Abs.