Drug Whisperer (Jan-Feb-March 2024)

  1. Viagra As An Alzheimer Prevention Agent? 
  2. Could Semiglutide Also Help With Obesity In Type 1 Diabetic Patients?
  3. Could BCG Vaccine Have A Role In Alzheimer’s Disease Prevention?

1. Viagra As An Alzheimer Prevention Agent? 

BACKGROUND: Alzheimer’s disease (AD) is a chronic neurodegenerative disease needing effective therapeutics urgently. Sildenafil, one of the approved phosphodiesterase-5 inhibitors, has been implicated as having potential effect in AD.

OBJECTIVE: To investigate the potential therapeutic benefit of sildenafil on AD.

METHODS: We performed real-world patient data analysis using the MarketScan® Medicare Supplemental and the Clinformatics® databases. We conducted propensity score-stratified analyses after adjusting confounding factors (i.e., sex, age, race, and comorbidities). We used both familial and sporadic AD patient induced pluripotent stem cells (iPSC) derived neurons to evaluate the sildenafil’s mechanism-of-action.

RESULTS: We showed that sildenafil usage is associated with reduced likelihood of AD across four new drug compactor cohorts, including bumetanide, furosemide, spironolactone, and nifedipine. For instance, sildenafil usage is associated with a 54% reduced incidence of AD in MarketScan® (hazard ratio [HR] = 0.46, 95% CI 0.32- 0.66) and a 30% reduced prevalence of AD in Clinformatics® (HR = 0.70, 95% CI 0.49- 1.00) compared to spironolactone. We found that sildenafil treatment reduced tau hyperphosphorylation (pTau181 and pTau205) in a dose-dependent manner in both familial and sporadic AD patient iPSC-derived neurons. RNA-sequencing data analysis of sildenafil-treated AD patient iPSC-derived neurons reveals that sildenafil specifically target AD related genes and pathobiological pathways, mechanistically supporting the beneficial effect of sildenafil in AD.

CONCLUSIONS: These real-world patient data validation and mechanistic observations from patient iPSC-derived neurons further suggested that sildenafil is a potential repurposable drug for AD. Yet, randomized clinical trials are warranted to validate the causal treatment effects of sildenafil in AD.

Gohel D, et al. Sildenafil as a Candidate Drug for Alzheimer’s Disease: Real-World Patient Data Observation and Mechanistic Observations from Patient-Induced Pluripotent Stem Cell-Derived Neurons. J Alzheimers Dis. 2024 Mar 1. doi: 10.3233/JAD-231391. Online ahead of print.

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2. Could Semiglutide Also Help With Obesity In Type 1 Diabetic Patients?

INTRODUCTION: More than two-thirds of patients with type 1 diabetes (T1D) are overweight (OW) and/or obese (OB) in the USA and Western Europe, resulting in insulin resistance as in type 2 diabetes. None of the currently available glucagon like polypeptide 1 (GLP-1) analogs are approved for patients with T1D. A higher dose of semaglutide has been approved by the Food and Drug Administration (FDA) for subjects with body mass index (BMI) >27 kg/m2. We evaluated the real-world use of semaglutide in patients with T1D. 

METHODS: This was a retrospective chart review study of 50 OW or OB patients with T1D who were initiated on semaglutide and followed for 1 year. The control group comprised of 50 computer-matched patients (for sex, race, weight, BMI, and diabetes duration) during a similar time period and were not on any weight loss medications. 

RESULTS: Most patients (92%) were non-Hispanic white in both arms. Mean ± standard deviation (SD) age and duration of diabetes were 42 ± 11 and 27 ± 12 years, respectively. The continuous glucose monitors (CGM), insulin pump use, baseline BMI and body weight were also similar in the two groups. Baseline glycosylated hemoglobin (HbA1c) was insignificantly lower in the semaglutide group (7.6% vs. 8.2%, respectively; P = non-significant [NS]).

Total daily insulin dose (TDD) and insulin dose per kg body weight were higher in the semaglutide group at baseline with no difference in basal or prandial insulin dose. There were significantly greater declines in mean (±SD), BMI (7.9% ± 2.6%), body weight (15.9 lbs ± 5.4 lbs), HbA1c, CGM glucose SD and coefficient of variation (CV), and increase in CGM time in range (TIR) in the semaglutide group compared to the control group with no difference in insulin dose changes, time above range (TAR), or time below range (TBR). 

CONCLUSIONS: We conclude that use of semaglutide in patients who are OW and/or OB with T1D was effective in lowering body weight and BMI, and improving glycemic metrics in this pilot real-world study. We strongly recommend performing prospective, large-randomized clinical trials with newer GLP-1 analogs like semaglutide and tirzepatide (twin-cretin) for subjects with T1D associated with OW and/or OB.

Garg SK, et al. Efficacy of Semaglutide in Overweight and Obese Patients with Type 1 Diabetes.  Diabetes Technol Ther 2024 Mar;26(3):184-189. doi: 10.1089/dia.2023.0490.

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3. Could BCG Vaccine Have A Role In Alzheimer’s Disease Prevention?

ABSTRACT: BCG vaccine has been used for 100 years to prevent tuberculosis. Not all countries, including the United States, adopted the initial World Health Organization recommendation to use BCG. Moreover, many Western countries that had routinely used BCG have discontinued its use. Recent population studies demonstrate lower prevalence of Alzheimer’s disease (AD) in countries with high BCG coverage. Intravesicular instillation of BCG is also used to treat bladder cancer that has not invaded the bladder muscle wall and has been shown to reduce recurrence. Several retrospective studies of bladder cancer patients demonstrated that BCG treatment was associated with a significantly reduced risk of developing AD. Plasma amyloid β assessment has become a fertile area of study for an AD biomarker that is predictive of a positive amyloid PET scan.

Mass spectrometry-based plasma amyloid 42/40 ratio has proven to be accurate and robust, and when combined with age and ApoE, is shown to accurately predict current and future brain amyloid status. These parameters, amyloid 42/40 ratio, age and ApoE genotype are incorporated into an Amyloid Probability Score (APS)-a score that identifies low, intermediate or high risk of having a PET scan positive for cerebral amyloid.

Community recruitment was used for this open-label pilot study. Forty-nine BCG-naïve, immunocompetent individuals completed our study: prior to BCG prime and boost, as determined by the APS, 34 had low risk (APS 0-35), 5 had intermediate risk (APS 36-57) and 10 had high risk (APS 58-100). The APS range for the participant group was 0 to 94. Follow-up plasma amyloid testing 9 months after vaccination revealed a reduction in the APS in all the risk groups: low risk group (p = 0. 37), intermediate risk group (p = 0.13) and the high-risk group (statistically significant, p = 0.016). Greater benefit was seen in younger participants and those with the highest risk.

The small number of participants and the nascent status of plasma amyloid testing will rightfully temper embracement of these results. However, both the favorable direction of change after BCG as well as the utility of the APS-a valuable surrogate AD biomarker-may prompt a definitive large-scale multicenter investigation of BCG and AD risk as determined by plasma amyloid peptide ratios and APS.

Dow CT, et al. Evaluation of BCG Vaccination and Plasma Amyloid: A Prospective, Pilot Study with Implications for Alzheimer’s Disease.  Microorganisms. 2022 Feb 12;10(2):424. doi:10.3390/microorganisms10020424.

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