Two-Year Prognostic Utility of Plasma p217+tau across the Alzheimer's Continuum

BACKGROUND

Plasma p217+tau has shown high concordance with cerebrospinal fluid (CSF) and positron emission tomography (PET) measures of amyloid-β (Aβ) and tau in Alzheimer's Disease (AD). However, its association with longitudinal cognition and comparative performance to PET Aβ and tau in predicting cognitive decline are unknown.

OBJECTIVES

To evaluate whether p217+tau can predict the rate of cognitive decline observed over two-year average follow-up and compare this to prediction based on Aβ (18F-NAV4694) and tau (18F-MK6240) PET. We also explored the sample size required to detect a 30% slowing in cognitive decline in a 2-year trial and selection test cost using p217+tau (pT+) as compared to PET Aβ (A+) and tau (T+) with and without p217+tau pre-screening.

DESIGN

A prospective observational cohort study.

SETTING

Participants of the Australian Imaging, Biomarker and Lifestyle Flagship Study of Ageing (AIBL) and Australian Dementia Network (ADNeT).

PARTICIPANTS

153 cognitively unimpaired (CU) and 50 cognitively impaired (CI) individuals.

MEASUREMENTS

Baseline p217+tau Simoa® assay, 18F-MK6240 tau-PET and 18F-NAV4694 Aβ-PET with neuropsychological follow-up (MMSE, CDR-SB, AIBL-PACC) over 2.4 ± 0.8 years.

RESULTS

In CI, p217+tau was a significant predictor of change in MMSE (β = -0.55, p < 0.001) and CDR-SB (β =0.61, p < 0.001) with an effect size similar to Aβ Centiloid (MMSE β = -0.48, p = 0.002; CDR-SB β = 0.43, p = 0.004) and meta-temporal (MetaT) tau SUVR (MMSE: β = -0.62, p < 0.001; CDR-SB: β = 0.65, p < 0.001). In CU, only MetaT tau SUVR was significantly associated with change in AIBL-PACC (β = -0.22, p = 0.008). Screening pT+ CI participants into a trial could lead to 24% reduction in sample size compared to screening with PET for A+ and 6-13% compared to screening with PET for T+ (different regions). This would translate to an 81-83% biomarker test cost-saving assuming the p217+tau test cost one-fifth of a PET scan. In a trial requiring PET A+ or T+, p217+tau pre-screening followed by PET in those who were pT+ would cost more in the CI group, compared to 26-38% biomarker test cost-saving in the CU.

CONCLUSIONS

Substantial cost reduction can be achieved using p217+tau alone to select participants with MCI or mild dementia for a clinical trial designed to slow cognitive decline over two years, compared to participant selection by PET. In pre-clinical AD trials, p217+tau provides significant cost-saving if used as a pre-screening measure for PET A+ or T+ but in MCI/mild dementia trials this may add to cost both in testing and in the increased number of participants needed for testing.

A Conformational Variant of p53 (U-p53AZ) as Blood-Based Biomarker for the Prediction of the Onset of Symptomatic Alzheimer's Disease

BACKGROUND

Ongoing research seeks to identify blood-based biomarkers able to predict onset and progression of Alzheimer's disease (AD).

OBJECTIVE

The unfolded conformational variant of p53 (U-p53AZ), previously observed in AD individuals, was evaluated in plasma samples from individuals participating in the Australian Imaging, Biomarkers and Lifestyle (AIBL) cohort for diagnostic and prognostic assessment, validated on a neuropsychological-based diagnosis, over the course of six years.

DESIGN

Retrospective Longitudinal Prognostic biomarker study.

SETTING

Single-center study based on the AIBL cohort.

PARTICIPANTS

482 participants of the AIBL cohort, aged 60-85 years, without uncontrolled diabetes, vascular disease, severe depression or psychiatric illnesses.

MEASUREMENTS

The AlzoSure® Predict test, consisting of immunoprecipitation (IP) followed by liquid chromatography (LC) tandem mass spectrometry (MS/MS), was performed to quantify the AZ 284® peptide as readout of U-p53AZ and compared with an independent neuropsychological diagnosis. The amyloid load via amyloid β-positron emission tomography (Aβ-PET) and supporting clinical information were included where possible.

RESULTS

U-p53AZ diagnostic and prognostic performance was assessed in both time-independent and time-dependent (36, 72 and 90 months following initial sampling) analyses. Prognostic performance of Aβ-PET and survival analyses with different risk factors (gender, Aβ-PET and APOE ε4 allele status) were also performed. U-p53AZ differentiated neuropsychologically graded AD from non-AD samples, and its detection at intermediate/high levels precisely identified present and future symptomatic AD. In both time-independent and time-dependent prognostic analyses U-p53AZ achieved area under the curve (AUC) >98%, significantly higher than Aβ-PET AUCs (between 84% and 93%, P respectively <0.0001 and <0.001). As single factor, U-p53AZ could clearly determine the risk of AD neuropsychological diagnosis over time (low versus intermediate/high U-p53AZ hazard ratio=2.99). Proportional hazards regression analysis identified U-p53AZ levels as a major independent predictor of AD onset.

CONCLUSIONS

These findings support use of U-p53AZ as blood-based biomarker predicting whether individuals would reach neuropsychologically-defined AD within six years prior to AD diagnosis. Integration of U-p53AZ in screening processes could support refined participant stratification for interventional studies.

Low dose thioguanine guided by therapeutic drug monitoring is a safe and effective alternative in inflammatory bowel disease patients intolerant to conventional thiopurines

BACKGROUND AND AIMS

Thioguanine is an alternative thiopurine for IBD patients. We evaluated the short-term efficacy and safety of low dose therapeutic drug monitored (TDM) thioguanine.

METHODS

A retrospective evaluation of IBD patients intolerant to conventional thiopurines started on thioguanine from 2017-2019 with dosing guided by TDM was conducted. Clinical response was defined for Ulcerative colitis (UC) as a reduction of partial MAYO score ≥ 3 with reduction in rectal bleeding score of at least 1 and a final rectal bleeding sub score of 0-1 at week 12 of therapy. Crohn's disease (CD) response was defined as a reduction of Harvey-Bradshaw index ≥ 3 (HBI) at week 12 of therapy. Remission was defined in UC as partial MAYO score of < 2 and in CD as HBI score of < 5.

RESULTS

46 patients were included in the study. The median thioguanine dose was 20 mg/day (SD 7.3, range: 10-40 mg/day) with a median 6-TGN level of 564 pmol/8×108 (IQR 517) for CD and 672 pmol/8×108 (IQR 349) for UC. The overall clinical response rate was 62% (13/21), intention to treat (ITT). Maintenance of remission was 76% (19/25, ITT). 37% (17/46) of patients experienced an adverse effect. No early cases of NRH were seen.

CONCLUSION

Thioguanine was tolerated well in 63% of patients. Clinical response was seen in 62 % of and maintenance of remission was high at 76 %. No cases of early NRH were seen. Longer-term follow-up is required to ensure safety and to assess durability of response. This article is protected by copyright. All rights reserved.

Infliximab vs. adalimumab in Crohn's disease: results from 327 patients in an Australian and New Zealand observational cohort study

BACKGROUND

Maintenance anti-tumour necrosis factor-α (anti-TNFα) treatment for Crohn's disease is the standard of care for patients with an inadequate response to corticosteroids and immunomodulators.

AIM

To compare the efficacy and safety of infliximab and adalimumab in clinical practice and assess the value of concomitant immunomodulator therapy.

METHODS

We performed an observational cohort study in consecutive patients with Crohn's disease qualifying for anti-TNFα treatment in Australia and New Zealand between 2007 and 2011. Demographic and clinical data were prospectively recorded to identify independent factors associated with induction and maintenance of response to infliximab or adalimumab, or to either anti-TNFα therapy.

RESULTS

Three hundred and twenty-seven patients (183 infliximab, 144 adalimumab) successfully applied for treatment. Eighty-nine percent responded in all groups and median maintenance of response was similar for the two agents. Concomitant immunomodulator with infliximab, but not adalimumab, demonstrated a significantly longer response overall (P = 0.002), and significantly fewer disease and treatment-related complications (P = 0.017). Corticosteroids at baseline, and/or in the preceding 12 months, were associated with a 9-13 times greater risk of disease flare during maintenance treatment as compared to no corticosteroids (P < 0.0001). Maintenance of response was similar in the anti-TNF naïve and anti-TNF experienced subgroups.

CONCLUSIONS

In this large, real-life study, we demonstrate infliximab and adalimumab to have similar response characteristics. However, infliximab requires concomitant immunomodulator to achieve optimal maintenance of response comparable to adalimumab monotherapy. The results of this study will assist clinicians in further optimising patient care in their day-to-day clinical practice.

Reduced alpha-defensin expression is associated with inflammation and not NOD2 mutation status in ileal Crohn's disease

BACKGROUND AND AIMS

Reduced ileal Paneth cell alpha-defensin expression has been reported to be associated with Crohn's disease, especially in patients carrying NOD2 mutations. The aim of this study was to independently assess whether NOD2, alpha-defensins and Crohn's disease are linked.

METHODS

Using quantitative real-time polymerase chain reaction (RT-PCR), we measured the mRNA expression levels of key Paneth cell antimicrobial peptides (DEFA5, DEFA6, LYZ, PLA2G2A), inflammatory cytokines [interkelukin 6 (IL6) and IL8], and a marker of epithelial cell content, villin (VIL1) in 106 samples from both affected ileum (inflamed Crohn's disease cases, n = 44) and unaffected ileum (non-inflamed; Crohn's disease cases, n = 51 and controls, n = 11). Anti-human defensin 5 (HD-5) and haematoxylin/eosin immunohistochemical staining was performed on parallel sections from NOD2 wild-type and NOD2 mutant ileal Crohn's disease tissue.

RESULTS

In Crohn's disease patients, DEFA5 and DEFA6 mRNA expression levels were 1.9- and 2.2-fold lower, respectively, in histologically confirmed inflamed ileal mucosa after adjustment for confounders (DEFA5, p<0.001; DEFA6, p = 0.001). In contrast to previous studies, we found no significant association between alpha-defensin expression and NOD2 genotype. HD-5 protein data supports these RNA findings. The reduction in HD-5 protein expression appears due to surface epithelial cell loss and reduced Paneth cell numbers as a consequence of tissue damage.

CONCLUSIONS

Reduction in alpha-defensin expression is independent of NOD2 status and is due to loss of surface epithelium as a consequence of inflammatory changes rather than being the inciting event prior to inflammation in ileal Crohn's disease.

Seasonal bone mass of college and senior female field hockey players

AIM

The purpose of the study was to observe the relationship of field hockey playing with bone, muscle and fat in young and older adult women.

METHODS

We measured body composition by dual energy X-ray absorptiometry (DXA) in college players, senior players and controls after a 4-month playing-season and 8-month off-season. Whole body (WB), proximal femur (PF), lumbar spine (LS), right and left forearm (RF, LF) bone mineral density (BMD), percent fat and lean mass of college players (20.6+/-1.1 years; 7.7+/-1 playing years) were compared with those of non-playing controls (19.5+/-1.5 years). BMD of senior players (37.3+/-10.3 years; 19.7+/-9.3 playing years) was compared to normative values. The differences between right and left forearm BMDs during the on and off seasons were also compared.

RESULTS

College player BMD was higher than controls at the WB (p=0.02), PF (p=0.00004), RF (p=0.006) and LF (p=0.005), but not the LS. Senior player BMD was higher than age-matched norms at the WB (p=0.001) and PF (p=0.006), but not the LS, RF or LF. There were no differences between on and off-season BMDs for either group. There were no differences between college player RF and LF BMD in either season, nor in the senior players during the off-season, however, during the season, senior players developed greater RF than LF BMD (p=0.02). College players had greater lean mass (p=0.00008) and lower fat mass than controls (p=0.003). Neither changed significantly between seasons. Senior players lost fat (p=0.04) and gained lean mass (p=0.02) in season.

CONCLUSION

Adult female field hockey players have higher than average bone mass that does not change significantly according to seasonal involvement.