Boxer, Adam L.

Abstract Background TMEM106B encodes a lysosomal protein and is a genetic susceptibility factor for frontotemporal lobar degeneration (FTLD). Aptamer‐based proteomics quantifies TMEM106B protein levels in CSF. The associations of CSF TMEM106B with measures of disease severity have not been previously evaluated, and the value of CSF TMEM106B as a clinical biomarker is unknown. Method CSF TMEM106B and NfL protein levels were quantified with aptamer‐based proteomics in participants from two independent cohorts: sporadic FTLD with neuropathology‐confirmed FTLD‐tau and FTLD‐TDP, clinically diagnosed PSP‐Richardson Syndrome, and controls (UCSF MAC, n = 95; mean age = 69 ± 6 yrs; 48% female) and familial FTLD comprised of presymptomatic and symptomatic FTLD mutation carriers with family non‐carrier controls (ALLFTD, n = 179; mean age = 49 ± 13 yrs; 53% female). The association between biomarkers and diverse measures of disease severity, including the CDR®+NACC‐FTLD and CDR®+NACC‐FTLD sum of boxes, were determined with linear regressions or mixed linear models. Associations with brain volumes were determined within the framework of voxel‐based morphometry. Result In both cohorts, at baseline, CSF TMEM106B did not differ by sex, age, FTLD phenotype, or CSF NfL. CSF TMEM106B was lower in cases with worse disease severity (Figure 1) and in participants with the protective TMEM106B rs1990622 G/G genotype, regardless of pathological diagnosis or FTLD‐causing mutation. Low CSF TMEM106B was associated with more severe longitudinal worsening in FTLD disease severity (Figure 2), basic and instrumental function, global cognition, executive function, and depression scores. These associations were weaker than those of NfL. Low CSF TMEM106B was associated with low brain volumes in frontal, parietal, and temporal regions (FWE‐corrected p < 0.05) (Figure 3A). CSF NfL negatively correlated (FWE‐corrected p < 0.05) with brain volumes in frontotemporal regions (Figure 3B). Conclusion CSF TMEM106B concentrations are influenced by the TMEM106B rs1990622 genotype, and correlate with disease severity and brain volume in both genetic and sporadic FTLD. Lower levels of CSF TMEM106B correlate with more severe disease and brain atrophy. Disease severity is more strongly associated with CSF NfL, while brain volumes are more strongly associated with CSF TMEM106B. CSF TMEM106B may have value as a biomarker of neurodegeneration in FTLD.

Abstract Background Corticobasal syndrome (CBS) is a neurodegenerative disease usually associated with accumulation of tau in the cortex and basal ganglia, leading to cognitive, movement, and behavioral symptoms that progressively impair function. Few clinical trials have ever been conducted in CBS, and perceptions and preferences about clinical trials in this population are largely unknown. Method An online survey was conducted (February 2015 ‐ November 2020) among research participants recruited through a multisite observational study (ARTFL). Responses from patients with CBS were tabulated and reported below. Result N=66 respondents had CBS as a primary or secondary phenotype (determined by study clinician), with 62% of surveys patient‐reported, and 38% completed by a caregiver/family member. Within CBS, 91% requested to be contacted about clinical trials. 2/6 decliners commented that disease severity precluded participation. 97% were willing to come in annually, 88% quarterly (3 months), 66% monthly, 43% weekly, and 17% would come in more than weekly; two patients could not travel due to disease severity. Comments included “we would live here for trials” and “whatever is needed.” Full day evaluations were acceptable to 91%, whereas 9% preferred a half‐day or less, although 65% would complete multi‐day evaluations spread over a week. Numerous remote and in person modes of assessment (e.g., surveys, examinations, cognitive testing, blood/saliva sampling, MRI, PET), were broadly acceptable by respondents (80‐93%), whereas remote activity monitoring (70%), lumbar puncture (68%), and remote video conferencing memory testing (67%) were less preferred, though still broadly acceptable. For distance willing to travel, 95% would travel 30 minutes, 91% one hour, 65% three hours, 54% five hours, and 37% would travel more than five hours or take a flight if needed. Travel reimbursement was very/extremely important for 40%, and unimportant for 26% (34% neutral). Feedback about clinical progression (81%), study results (74%), and an open‐label extension (68%) were factors identified as the highest importance to patients. Conclusion Patients with CBS are eager to participate in clinical trials, even trials that are complex, far away, and have visits over multiple days. Travel reimbursement, providing feedback to patients, and access to experimental treatments were key considerations.