By Cameron Johnston
TORONTO -- August 11, 2009 -- Patients with thyroid cancers who are refractory to radioactive iodine therapy, and/or have progressed following surgical resection of the thyroid seem to show favourable responses when treated with sunitinib, according to a study presented here at the World Congress on Thyroid Cancer (WCTC).
Ezra Cohen, MD, University of Chicago, Chicago, Illinois, presented the preliminary results of a phase 2 study at an oral presentation on August 8.
The study results included only patients with differentiated cancers; the results from a second cohort of patients with medullary carcinomas were not presented.
Patients in the study had either papillary (n = 18), follicular (n = 8), Hurthle cell (n = 10), or insular (n = 2) thyroid cancer.
Of the 38 who were enrolled, 37 had been treated with radioactive iodine, 35 had had prior surgery, 15 had had external beam radiation therapy (EBRT), and 6 had had systemic chemotherapy. Many had a combination of therapies.
All patients had shown signs of progressive disease within the previous 6 months before being enrolled in the study. Thirty-one patients had distant metastases at the time of enrolment.
Patients were treated with sunitinib 50 mg/day on a 4-week-on/2-week-off cycle.
Overall, 26 patients (68%) had stable disease and 7 (18%) had a partial response. Progression-free survival was 57% and 34% at 1 and 2 years respectively. Overall survival was 76% and 70% at 1 and 2 years respectively.
Treatment response was determined according to modified Response Evaluation Criteria in Solid Tumors (RECIST) criteria as well as by the patient's decrease in thyroglobulin levels.
Adverse events were very common in this study group, although according to Dr. Cohen, they were not unexpected and were comparable to what had been seen in other studies when sunitinib was used to treat renal cell carcinoma.
A total of 5 patients discontinued the study due to adverse events, which included fatigue (79%), diarrhoea (56%), and hand-foot syndrome (53%). There were also 3 toxic deaths, which were felt to be related to the sunitinib (1 case of sepsis, 1 of liver failure, and 1 of left ventricular failure).
Half of the patients (19/38) had to undergo dose reductions as a result of the aggressive toxicity profile.
Nonetheless, Dr. Cohen said sunitinib is an active agent, showing an 87% response rate among patients whose thyroid carcinomas were refractory to virtually all other available treatments.
[Presentation title: Sunitinib in Patients With Radioactive Iodine Refractory and Progressive Differentiated Thyroid Cancer: A Phase 2 Study. Abstract O51]
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