18F-MFBG PET imaging in patients with neuroblastoma: Lesion targeting and comparison with MIBG.

Abstract

10046 Background: 123I-MIBG gamma camera imaging (MIBG) is routinely used for the imaging of neuroblastoma. Limitations include need for two-day imaging schedule and lack of quantitative uptake measurements. Phase I study showed that 18 F-MFBG (MFBG), a positron-emitting analog of MIBG, is safe and feasible (PMID:28705916). In the follow-up phase II trial (NCT02348749) we evaluated MFBG PET imaging, comparing neuroblastoma lesion between the two modalities. Methods: Patients with known neuroblastoma underwent whole- body PET CT or PET-MR imaging one hour post-injection with 8mCi/1.7m2 of MFBG. All patients had concurrent MIBG scan with planar and SPECT-CT imaging without intervening therapy. MFBG and MIBG images were independently analyzed for lesion targeting; lesion number, site and uptake was noted for each patient and compared. Discordant lesions were further investigated with correlative imaging and/or clinical follow up. MFBG score was generated, similar to the modified Curie score for MIBG, for each patient. Results: 25 patients (median age 8 y) underwent MFBG scans at a median of 2 (range 0-24) days after MIBG scans; in one patient MFBG scan was performed 1 day before MIBG scan. No MFBG-related adverse events were noted. 24 patients had both MIBG and MFBG positive scans while 1 patient had both MIBG and MFBG negative scans. A total of 367 lesions were visualized on MFBG as against 217 on MIBG. There were no MIBG-positive that were negative on MFBG. A median number of 11 (range 0-57) lesions per patient were detected on MFBG scan. Uptake was noted in osteomedullary only, (n=13), soft tissue only (n=1) and both soft tissue and osseous lesions (n=10). MFBG detected a median of 6 (range 1-24) additional lesions in 19 patients. In 16/19 patients where follow up was available, the discordance was related to true positive disease, including at least 116 sites. Respective median curie scores were 3 (range:0-22) and 9 (range:0-24) with MIBG and MFBG respectively. Conclusions: MFBG scan detected disease in all patients with MIBG positive disease. MFBG detected similar or more lesions compared to MIBG in patients with neuroblastoma, with overall increased scores. Further analysis to evaluate impact on patient management is underway. Clinical trial information: NCT02348749 .