Recombinant Human TSH Superagonists for Imaging of Thyroid Cancer

DESCRIPTION (provided by applicant): Thyroid cancer is increasingly prevalent and the most common malignancy of endocrine tissues, and most patients require lifelong surveillance with diagnostic thyroid-stimulating hormone (TSH)-stimulated radioiodine uptake as well as thyroid remnant or tumor ablation with radioiodine therapy. Other imaging techniques including ultrasound and positron-emission tomography have also gained increasing importance as follow-up surveillance methods. However these other methods are not intrinsically specific for thyroid tissue and there remains a need for novel thyroid specific imaging methods, especially for tumors increasingly recognized by thyroglobulin production but with poor radioiodide uptake due to absent or decreased sodium-iodide symporter expression. The PI, who was both co-inventor and co-developer with Genzyme of wild type recombinant hTSH (Thyrogen), currently approved for diagnostic imaging of thyroid cancer, now proposes to develop novel radiolabeled high affinity hTSH analogs and/or analog-coated nanoparticles for imaging of thyroid cancer through targeting the highly specific TSH receptor. During our highly scored and successfully completed phase 1 SBIR study we have achieved all the aims including optimization of stable cell lines producing high levels of the final two candidate super active analogs; optimization of large scale bioreactor production methods; development of novel, high capacity purification methods suitable for commercial scale-up; and rigorous quantification and characterization of purified analogs by multiple physicochemical methods. We also used a selected radiolabeled TSH super agonist analog to develop a novel technology for enhanced imaging of thyroid cancer and provided preliminary data for even a newer technology of analog-coated nanoparticles containing imaging agents. In the current phase 2 proposal, we plan to produce and purify additional large amounts of the final two TSH analog candidates sufficient for all the phase 2 studies using the methods of production, purification and radio labeling optimized in the phase 1 study. We also plan to continue development and optimization of various xenograft, transgenic and orthotopic models of thyroid cancer to be used in the various imaging studies proposed with both directly labeled analogs as well as analog-coated liposome nanoparticles containing fluorescent and radiolabeled imaging agents. In addition, quantitative uptake studies of radiolabeled TSH analogs will include various thyroid tumor models and biodistribution to multiple organs. This novel labeled TSH analog or targeted nanoparticle imaging method may later be extended to improved therapeutic approaches for thyroid cancer including TSH receptor-mediated delivery of therapeutic agents such as radionuclides or toxins as well as radioguided surgery. PUBLIC HEALTH RELEVANCE: Thyroid cancer is the most common malignancy of endocrine tissues and most patients require lifelong surveillance with diagnostic thyroid-stimulating hormone (TSH)-stimulated radio-iodine imaging to detect recurrent tumor. The PI has developed a much improved form of TSH and proposes a completely new method of thyroid cancer imaging using novel recombinant TSH superagonist analogs that should greatly improve early detection and lead to improved cancer treatment and survival.