Abstract TP368: Relevance of Lesion Volume as an Outcome in Cerebral Cavernous Malformation Drug Trial

Background: It is not clear if changes in lesion volume might represent a clinically relevant and statistically advantageous outcome parameter in early phase trials of novel drugs aimed at preventing bleeding in cerebral cavernous malformations (CCM). Methods: We analyzed the modified intention to treat cohort (33 patients receiving atorvastatin and 31 placebo) who contributed at least one paired imaging biomarker in the recently completed double-blinded randomized controlled AT CASH EPOC trial (clinicaltrials.gov NCT02603328). We examined prospective changes in CCM lesion volume and correlated these with symptomatic hemorrhage (SH) events. We contemporaneously assessed changes in lesional iron content by quantitative susceptibility mapping (QSM) on MRI, and objective (mRS) and subjective (EQ-VAS) functional status. We also simulated sample sizes needed to detect potential effects of a drug on lesion volume. Results: There was excellent correlation between independently assessed maximum lesion diameter and CCM lesion volume (R 2 = 0.68, P<0.0001). The mean (SD) percentage change in lesion volume per year was +6 (65) and +18 (94) in atorvastatin and placebo patients, respectively (P= 0.43). All cases with SH had increases in lesion volume as well as increases in mean lesional iron content by QSM, and most had declines in functional status on mRS and EQ-VAS. But there were many cases with increases in lesion volume with improved functional status or decreased mean lesional QSM, and other cases with worsening in function or increased lesional QSM and decreased lesion volume. There were no significant correlations of changes in lesion volume with concomitant changes in mean lesional QSM, mRS or EQ-VAS (all R/R 2 <0.5 and Bonferroni corrected P>0.05), including in brainstem lesions analyzed separately. Sample size simulations indicate larger numbers of cases needed to demonstrate a drug effect on changes in lesion volume than those needed to detect an effect on QSM change with a=0.05 and b=0.8, and even larger samples to detect effects on the proportion of cases with increased or decreased lesion volume. Conclusion: Changes in lesion volume occur frequently in CCM lesions after recent SH, but do not correlate with measures of bleeding in the lesions, nor appear to reflect functional changes. And they are not statistically advantageous in comparison to QSM measures for detecting potential drug effects.