Summary
Background
About half of patients with papillary thyroid cancer have tumours with activating BRAFV600E mutations. Vemurafenib, an oncogenic BRAF kinase inhibitor approved for BRAF-positive melanoma, showed clinical benefit in three patients with BRAFV600E-positive papillary thyroid cancer in a phase 1 trial. We aimed to establish the activity of vemurafenib in patients with BRAFV600E-positive papillary thyroid cancer.
Methods
We did an open-label, non-randomised, phase 2 trial at ten academic centres and hospitals worldwide in patients aged 18 years or older with histologically confirmed recurrent or metastatic papillary thyroid cancer refractory to radioactive iodine and positive for the BRAFV600E mutation. Participants either had never received a multikinase inhibitor targeting VEGFR (cohort 1) or had been treated previously with a VEGFR multikinase inhibitor (cohort 2). Patients received vemurafenib 960 mg orally twice daily. The primary endpoint was investigator-assessed best overall response in cohort 1 (confirmed on two assessments 4 weeks or longer apart). Analyses were planned to have a minimum median follow-up of 15 months (data cutoff April 18, 2014) and were done in safety, intention-to-treat, and per-protocol populations. This trial is closed and is registered at ClinicalTrials.gov, number NCT01286753.
Findings
Between June 23, 2011, and Jan 15, 2013, 51 patients were enrolled to the study, 26 in cohort 1 and 25 in cohort 2. Median duration of follow-up was 18·8 months (IQR 14·2–26·0) in cohort 1 and 12·0 months (6·7–20·3) in cohort 2. Partial responses were recorded in ten of 26 patients in cohort 1 (best overall response 38·5%, 95% CI 20·2–59·4). Grade 3 or 4 adverse events were recorded in 17 (65%) of 26 patients in cohort 1 and 17 (68%) of 25 patients in cohort 2; the most common grade 3 and 4 adverse events were squamous cell carcinoma of the skin (seven [27% ] in cohort 1, five [20% ] in cohort 2), lymphopenia (two [8% ] in each cohort), and increased γ-glutamyltransferase (one [4% ] in cohort 1, three [12% ] in cohort 2). Two individuals in cohort 2 died due to adverse events, one from dyspnoea and one from multiorgan failure, but neither was treatment related. Serious adverse events were reported for 16 (62%) of 26 patients in cohort 1 and 17 (68%) of 25 patients in cohort 2.
Interpretation
Vemurafenib showed antitumour activity in patients with progressive, BRAFV600E-positive papillary thyroid cancer refractory to radioactive iodine who had never been treated with a multikinase inhibitor. As such, this agent represents a potential new treatment option for these patients.
The cDNA microarray is one technological approach that has the potential to accurately measure changes in global mRNA expression levels. We report an assessment of an optimized cDNA microarray platform to generate accurate, precise and reliable data consistent with the objective of using microarrays as an acquisition platform to populate gene expression databases. The study design consisted of two independent evaluations with 70 arrays from two different manufactured lots and used three human tissue sources as samples: placenta, brain and heart. Overall signal response was linear over three orders of magnitude and the sensitivity for any element was estimated to be 2 pg mRNA. The calculated coefficient of variation for differential expression for all non-differentiated elements was 12-14% across the entire signal range and did not vary with array batch or tissue source. The minimum detectable fold change for differential expression was 1.4. Accuracy, in terms of bias (observed minus expected differential expression ratio), was less than 1 part in 10 000 for all non-differentiated elements. The results presented in this report demonstrate the reproducible performance of the cDNA microarray technology platform and the methods provide a useful framework for evaluating other technologies that monitor changes in global mRNA expression.
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