Conditions: Papillary Thyroid Carcinoma
Keywords: thyroid cancer Tall cell PTC Poorly differentiated thyroid carcinoma metastatic
Allocation: NA | Intervention model: SINGLE_GROUP
Enrollment: 10
Healthy volunteers: no

Brief summary:
Radioactive iodine therapy is often part of the standard treatment for Papillary Thyroid Carcinoma (PTC) patients. However, in many patients, tumors develop a resistance or no longer respond to radioactive iodine therapy (iodine-refractory). Several lines of evidence suggest that blocking the BRAF gene may help to re-sensitize the tumors to radioactive iodine. BRAF is a protein that plays a central role in the growth and survival of cancer cells in some types of PTC. The investigational drug GSK2118436 may work by blocking the BRAF protein in cancer cells lines and tumors that have a mutated BRAF gene.

In this research study, the investigators are looking to see if GSK2118436 can re-sensitize iodine-refractory PTC to radioactive iodine therapy. The investigators are also looking at the safety of adding GSK2118436 to radioactive iodine therapy.

Detailed description:
You will take GSK2118436 capsules by mouth for 28 straight days. If your Day 28 whole body radioactive iodine scan demonstrates significant uptake of iodine, you will take GSK2118436 for an additional 14 days (Days 29-42). You will be given a drug diary to record when you take GSK2118436. This diary will also contain instructions on how to take GSK2118436.

Prior to Day 1

* Optional fine needle aspirate (pre-treatment) Day 1
* Vital signs
* Routine blood tests (2 tablespoons)
* Research blood sample for Circulating Tumor Cells (CTCs). (4 teaspoons of blood)
* Optional research blood sample for CTCs 4-6 hours after the first dose of GSK2118436

Day 2:

* Optional research blood sample for CTCs 4-6 hours after the first dose of GSK2118436 Day 3-5: Research blood sample for CTCs Days 8 and 15
* Vital signs
* Routine blood tests (2 tablespoons)
* Research blood sample for CTCs. (4 teaspoons of blood)
* Optional fine needle aspirate (Day 15 only) Low Iodine Diet: You will begin a low iodine diet on Day 15, in preparation for Day 23 when you will receive radioactive iodine (131I). The study team will provide you with instructions on this diet. The low iodine diet will be continued until the whole body scan is complete. For those participants who will receive a therapeutic dose of radioactive iodine on Day 37, the low iodine diet will be continued until the Day 42 whole body scan is complete.

Days 21 and 22: The drug thyrogen will be administered as in injection into your buttocks on Days 21 and 22 in preparation for your whole body radioactive iodine scan on Day 28. Thyrogen is used as a diagnostic tool to help determine the status of your cancer and is approved for use in thyroid cancer patients.

Day 23: To prepare for the whole body radioactive iodine scan, you will be asked to swallow a capsule of radioactive iodine which will be absorbed by any remaining thyroid cells in your body. Radioactive iodine is approved for use in thyroid cancer patients. You will then be asked to return for the scan on Day 28.You will be asked to sign a separate consent for the radioactive iodine.

Days 1-28:

* Optional repeat fine needle aspirate Day 28
* Whole body radioactive iodine scan to assess your thyroid cancer

If your Day 28 whole body radioactive iodine scan demonstrates significant uptake of iodine, you will have the following tests done within 24 hours:

* Vital signs
* Routine blood tests (2 tablespoons)
* Research blood sample for CTCs. (4 teaspoons of blood)
* An injection of a therapeutic dose of radioactive iodine will be administered. If your Day 28 whole body radioactive iodine scan does not demonstrate significant uptake of iodine, you will be removed from the research study. You will have a 3 month follow up appointment as outlined below.

If your Day 28 whole body radioactive iodine scan demonstrates significant uptake of iodine, you will continue treatment with GSK2118436 and have the following study visits:

Days 35 and 36: The drug thyrogen will be administered as in injection into your buttocks on Days 35 and 36 in preparation for your whole body radioactive iodine scan on Day 42.

Day 37: You will be given a therapeutic dose of radioactive iodine. You will be given a separate consent form to sign for your radioactive iodine treatment. You will then be asked to return for the whole body radioactive iodine scan on Day 42.

Day 39:

* Vital signs
* Routine blood tests (1 tablespoon)

Day 42:

* Whole body radioactive iodine scan
* Research blood sample for CTCs. (4 teaspoons of blood)

After the final dose of the study drug: All participants will have a follow up visit 3 months after you stop the study drug. You will have the following tests at this visit:

* Routine blood tests (2 tablespoons)
* Research blood sample for CTCs. (4 teaspoons of blood)
* An assessment of your tumor by CT scan or PET/CT scan of your neck, chest, abdomen and pelvis.
* Those participants who had a therapeutic dose of radioactive iodine on Day 37 will have a whole body radioactive iodine scan.
* Optional fine needle aspirate

Arms:
arm 1: Intervention: GSK2118436 (dabrafenib) 150mg by mouth twice per day for 28 days, continued to day 42 if the Day 25 Iodine-131 scan shows new uptake. Patients with new Iodine-131 uptake on Day 25 who continue dabrafenib to day 42 receive a treatment dose (150 mCi) of Iodine-131 on Day 37.

Interventions: intervention 1: GSK2118436
Intervention descriptions: intervention 1: 150mg twice per day orally for 28 days (42 days if Iodine-131 scan on Day 25 shows new uptake)

Protocol document: