Association between new-onset hypothyroidism and clinical response in patients treated with tyrosine kinase inhibitor therapy in phase I clinical trials.

Tyrosine kinase inhibitor (TKI)-induced thyroid dysfunction has been identified as an important but manageable adverse effect of targeted therapy. Several studies have suggested that patients who develop hypothyroidism respond better to TKIs, but this relationship is not well elucidated. We evaluated the relationship between new-onset hypothyroidism and clinical response in patients with advanced cancers treated with TKIs at our institution.

We retrospectively reviewed records for patients from four clinical trials that included at least one TKI therapy between January 2006 and December 2011. Patients with preexisting thyroid disease, including thyroid cancer, hypothyroidism, or hyperthyroidism, were excluded. Analysis of 197 patients was performed. Response was determined using RECIST 1.0. Clinical benefit was described as complete response, partial response, or stable disease greater than 4 months. Multivariable logistic regression analysis was performed to correlate patient characteristics with clinical response.

The median age for the 197 patients was 58 years (range, 13-85 years), and 56 % were female. Of the 197 patients, 52 (26 %) developed hypothyroidism after therapy. Clinical benefit rates were 50 % in patients with new-onset hypothyroidism versus 34 % in patients without hypothyroidism. In the univariate model, the odds ratio (OR) for new-onset hypothyroidism was 1.9 [95 % confidence interval (CI) (1.0, 3.6) and p = 0.05]. We grouped tumor types into six categories (breast, colorectal carcinoma, melanoma, non-small cell lung cancer, pancreas, and other). When adjusted for tumor type, age (>50 years) and sex, the OR was 2.9 [95 % CI (1.3, 6.5) and p = 0.012] for new-onset hypothyroidism.

New-onset hypothyroidism was associated with favorable clinical response in patients who received TKI treatment.