New Pathways to Medicare Coverage for Innovative PET Radiopharmaceuticals: Report of a Medical Imaging & Technology Alliance (MITA) Workshop

Quantifying murine bone marrow and blood radiation dose response following (18)F-FDG PET with DNA damage biomarkers

The purpose of this study was to quantify the poorly understood radiation doses to murine bone marrow and blood from whole-body fluorine 18 ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET), by using specific biomarkers and comparing with whole body external low dose exposures. Groups of 3-5 mice were randomly assigned to 10 groups, each receiving either a different activity of (18)F-FDG: 0-37MBq or whole body irradiated with corresponding doses of 0-300mGy X-rays. Blood samples were collected at 24h and at 43h for reticulocyte micronucleus assays and QPCR analysis of gene expression in peripheral blood leukocytes. Blood and bone marrow dose estimates were calculated from injected activities of (18)F-FDG and were based on a recommended ICRP model. Doses to the bone marrow corresponding to 33.43mGy and above for internal (18)F-FDG exposure and to 25mGy and above for external X-ray exposure, showed significant increases in radiation-induced MN-RET formation relative to controls (P<0.05). Regression analysis showed that both types of exposure produced a linear response with linear regression analysis giving R(2) of 0.992 and 0.999 for respectively internal and external exposure. No significant difference between the two data sets was found with a P-value of 0.493. In vivo gene expression dose-responses at 24h for Bbc3 and Cdkn1 were similar for (18)F-FDG and X-ray exposures, with significant modifications occurring for doses over 300mGy for Bbc3 and at the lower dose of 150mGy for Cdkn1a. Both leucocyte gene expression and quantification of MN-RET are highly sensitive biomarkers for reliable estimation of the low doses delivered in vivo to, respectively, blood and bone marrow, following (18)F-FDG PET.

The Medical Imaging & Technology Alliance conference on research endpoints appropriate for Medicare coverage of new PET radiopharmaceuticals

The outcomes of a 2011 Medical Imaging & Technology Alliance (MITA) conference helped shape considerations about what might be the most appropriate pathways for the regulatory and payment considerations of new PET radiopharmaceuticals. As follow-up to that conference, MITA convened a second conference of stakeholders to advise payers on what might be acceptable endpoints for clinical trials to support the coverage of novel PET agents. The conference involved experts on imaging and clinical research, providers of PET services, as well as representatives of interested medical societies, the PET industry, and the regulatory and payer communities. The principal outcome of their deliberations was that it was unrealistic to expect trials of new PET radiopharmaceuticals to directly demonstrate a health benefit. Rather, intermediate outcomes, such as a positive change in patient management, would be more efficient and appropriate.