Martin, Peter R.

e17580 Background: Cabozantinib is a small molecule multiple-receptor tyrosine kinase inhibitor that primarily targets MET and vascular endothelial growth factor receptor 2 (VEGFR2). We evaluated the effect of cabozantinib on BTM in RAIR DTC. We also assessed the response of BM to cabozantinib using 18F Sodium Fluoride (NaF) PET and radionuclide bone scans. Methods: This prospective analysis was performed as part of a multicenter International Thyroid Oncology Group phase II study of cabozantinibin patients with RAIR DTC who progressed on prior VEGFR-targeted therapy (NCT01811212). BTM [serum C-telopeptide (CTx), osteocalcin, N-telopeptide (NTx), procollagen type 1 (Pc1) and urinary NTx] and NaF PET or Tc-MDP scans were done at baseline and after 8 weeks of therapy. A paired t-test was used between baseline and week 8 BTM. Results: Primary study results were presented elsewhere (Shah, et al. 2015, International Thyroid Congress) showing a response rate of 36% with cabozantinib. Of 25 patients (pts) enrolled, 21 had BM, 10 of whom were on bone-modifying agents (BMA) prior to week 8. Only 2 pts had elevated BTM at baseline. In all pts who had paired BTM, there was a statistically significant decline in all BTM except NTx by week 8 (table). Pts not on BMA also had a significant decline in CTx (p 0.0003), urine NTx (p 0.0300), and Pc1 (p 0.0030) compared to baseline. 19 pts were evaluable for overall response and there was no correlation between BTM and response rate. 6/21 patients underwent paired NaF PET scans and 4/6 had minor reduction in lesion uptake at 8 weeks. Conclusions: Interestingly, most of our patients had normal baseline BTM despite BM. Cabozantinib was associated with a strikingly significant reduction in all BTM (even when BTM were within normal limits at baseline) except NTx by week 8. Minor decreases in bone lesion uptake was noted on NaF PET in 4/6 evaluable patients. Clinical trial information: NCT01811212. [Table: see text]

Background: Despite common pathology, Alzheimer’s disease (AD) can have multiple clinical presentations which pathological studies suggest result from differences in the regional distribution of tau pathology. Positron emission tomography (PET) ligands are now available that can detect tau proteins in vivo and hence can be used to investigate the biological mechanisms underlying atypical AD. Objective: To assess regional patterns of tau uptake on PET imaging in two atypical AD variants, posterior cortical atrophy (PCA) and logopenic progressive aphasia (lvPPA). Methods: Eighteen PCA and 19 lvPPA subjects that showed amyloid-β deposition on PET underwent tau-PET imaging with [ 18 F]AV-1451. Group comparisons of tau uptake in PCA and lvPPA were performed using voxel-level and regional-level analyses. We also assessed the degree of lobar tau asymmetry and correlated regional tau uptake to age and performance on clinical evaluations. Results: Both syndromes showed diffuse tau uptake throughout all cortical regions, although PCA showed greater uptake in occipital regions compared to lvPPA, and lvPPA showed greater uptake in left frontal and temporal regions compared to PCA. While lvPPA showed predominant left-asymmetric tau deposition, PCA was more bilateral. Younger subjects showed greater tau uptake bilaterally in frontal and parietal lobes than older subjects, and sentence repetition, Boston naming test, simultanagnosia, and visuoperceptual function showed specific regional tau correlates. Conclusion: Tau deposition is closely related to clinical presentation in atypical AD with age playing a role in determining the degree of cortical tau deposition.

ObjectivesTo assess [18F]AV‐1451 tau‐PET (positron emission tomography) uptake patterns across the primary progressive aphasia (PPA) variants (logopenic, semantic, and agrammatic), examine regional uptake patterns of [18F]AV‐1451 independent of clinical diagnosis, and compare the diagnostic utility of [18F]AV‐1451, [18F]‐fluorodeoxygluclose (FDG)‐PET and MRI (magnetic resonance imaging) to differentiate the PPA variants.MethodsWe performed statistical parametric mapping of [18F]AV‐1451 across 40 PPA patients (logopenic‐PPA = 14, semantic‐PPA = 13, and agrammatic‐PPA = 13) compared to 80 cognitively normal, Pittsburgh compound B–negative controls, age and gender matched 2:1. Principal component analysis of regional [18F]AV‐1451 tau‐PET standard uptake value ratio was performed to understand underlying patterns of [18F]AV‐1451 uptake independent of clinical diagnosis. Penalized multinomial regression analyses were utilized to assess diagnostic utility.ResultsLogopenic‐PPA showed striking uptake throughout neocortex, particularly temporoparietal, compared to controls, semantic‐PPA, and agrammatic‐PPA. Semantic‐PPA and agrammatic‐PPA showed milder patterns of focal [18F]AV‐1451 uptake. Semantic‐PPA showed elevated uptake (left>right) in anteromedial temporal lobes, compared to controls and agrammatic‐PPA. Agrammatic‐PPA showed elevated uptake (left>right) throughout prefrontal white matter and in subcortical gray matter structures, compared to controls and semantic‐PPA. The principal component analysis of regional [18F]AV‐1451 indicated two primary dimensions, a severity dimension that distinguished logopenic‐PPA from agrammatic‐PPA and semantic‐PPA, and a frontal versus temporal contrast that distinguishes agrammatic‐PPA and semantic‐PPA cases. Diagnostic utility of [18F]AV‐1451was superior to MRI and at least equal to FDG‐PET.Interpretation[18F]AV‐1451binding characteristics differ across the PPA variants and were excellent at distinguishing between the variants. [18F]AV‐1451binding characteristics were as good or better than other brain imaging modalities utilized in clinical practice, suggesting that [18F]AV‐1451 may have clinical diagnostic utility in PPA. Ann Neurol 2018 Ann Neurol 2018;83:599–611