PBT2
   HOME

TheInfoList



OR:

PBT2 is a safe-for-human-use Zinc
ionophore In chemistry, an ionophore () is a chemical species that reversibly binds ions. Many ionophores are lipid-soluble entities that transport ions across the cell membrane. Ionophores catalyze ion transport across hydrophobic membranes, such as liq ...
and an experimental drug candidate. It is a second-generation 8-hydroxyquinoline
analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog ...
intended to be a successor to clioquinol and a potential treatment of
Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As ...
and
Huntington's disease Huntington's disease (HD), also known as Huntington's chorea, is a neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental abilities. A general lack of coordination and an uns ...
.


Clinical trials

PBT2 was the subject of three phase II clinical trials for Alzheimer's disease ('EURO'), 'IMAGINE' & 'IMAGINE EXTENSION') and one for
Huntington's disease Huntington's disease (HD), also known as Huntington's chorea, is a neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental abilities. A general lack of coordination and an uns ...
('REACH2HD') trial. The cognition efficacy results for Alzheimer's disease were mixed. The EURO trial showed some improvements in cognitive functions, in particular executive function domains, while the IMAGINE study did not."Prana Biotech Plunges 76%; Drug Fails in Alzheimer Study""PBT2 Takes a Dive in Phase 2 Alzheimer's Trial" Although there is no evidence that PBT2 is of any benefit in Alzheimer's dementia,''"There is no evidence that MPACs (PBT1 or PBT2) are of benefit in Alzheimer's dementia"'' the number of subjects treated with PBT2 for AD in Phase II placebo controlled trials (N~76) is limited and the trials were not powered to detect cognitive outcomes. In the Phase II PBT2 trial in Huntington disease, whilst the overall cognitive composite measured was not improved, an executive function domain within the composite was significantly improved.


Phase II studies in AD

PBT2-201 (EURO) was a 12-week randomized, double-blind, placebo-controlled, parallel three-group study (Phase II) to assess the safety, tolerability and efficacy of two dose levels of PBT2 to slow progression of disease in patients with early AD. Seventy-eight (78) patients were enrolled and all were evaluated for safety and efficacy. PBT2 treatment of 50 and 250 mg a day was well tolerated in patients with AD during 12 weeks of treatment, with some evidence that the PBT2 250 mg/day dose can modulate certain biomarkers associated with AD, notably a significant decrease in CSF Abeta levels, and improvement in aspects of cognitive function as measured by the Executive Function composite z score and the individual Trails Making Test (TMT) Part B and the Category Fluency tests. PBT2-204 (IMAGINE) was a 12-month brain amyloid imaging study in which patients with mild AD (n=42) were administered PBT2 250 mg or placebo. Forty-two (42) patients were enrolled and all were evaluated for safety and efficacy. PBT2 was shown to be safe and very well tolerated over the 52 weeks, with the adverse event profile equivalent between placebo and treated groups. There was no difference in brain amyloid levels between the PBT2- and placebo-treated groups as measured by PiB. PBT2-204-Ext (Extension) Thirty-three (n=33) patients continued on 250 mg PBT2 in an open-label extension study and were evaluated for safety and efficacy, with n=27 patients completing the study. The safety findings indicate that longer-term treatment (up to 104 weeks) with PBT2 250 mg was well tolerated in patients with prodromal or mild AD. The safety findings from this study are consistent with those that would be expected in a population of elderly adults with prodromal or mild AD.


Phase II study in HD

PBT2-203 (Reach2HD) was a 6-month safety, tolerability and efficacy study in HD. Patients with early to mid-stage HD (n=109) received PBT2 100 mg, PBT2 250 mg or placebo once daily. The primary objective of the study was to evaluate the safety and tolerability of two dose levels of PBT2 (100 mg and 250 mg, once daily) compared to Placebo after 26 weeks in participants with early to mid-stage HD. PBT2 was shown to be safe and well tolerated over the 26 weeks, with the adverse event profile equivalent between placebo and PBT2 groups. The secondary objectives of the study focused on the specific symptoms or manifestations of HD. The primary efficacy objective of the study was to determine the effect of PBT2 on cognition as measured by a cognitive test battery consisting of Category Fluency Test, TMT Parts A and B, Map Search, Symbol Digit Modalities Test, Stroop Word Reading Test, Speeded Tapping Task and MoCA. The results of these assessments were used to calculate three composite z-scores of cognition – the Main Composite z-score, Exploratory Composite z-score and Executive Function z-score. PBT2 showed signs of improving some aspects of cognitive function in the study. The 250 mg dose of PBT2, administered once daily, showed better and statistically significant efficacy over the 12-week treatment period compared to placebo for the Main Composite Cognition Score (p=0.020), Exploratory composite cognition z-score (p=0.016), Executive Function composite Z score (p=0.005) and TMT Part B (p<0.001), a cognitive assessment tool. At 26 weeks, TMT Part B was statistically significantly improved (p=0.042) and the Executive Function composite z score trending to improvement. In patients with early HD (Total Functional Capacity 11-13), the Executive Function composite z score was statistically significantly improved (p=0.038). Overall the results indicate that larger trials are needed to fully assess the safety and efficacy profile of PBT2 in AD and HD.


Other applications

PBT2 has been studied for its potential use in the treatment of infections with
multidrug-resistant bacteria Multidrug-resistant bacteria (MDR bacteria) are bacteria that are resistant to three or more classes of antimicrobial drugs. MDR bacteria have seen an increase in prevalence in recent years and pose serious risks to public health. MDR bacteria c ...
. In combination with zinc, PBT2 has been shown to reverse
antibiotic resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. ...
for a number of clinically significant bacterial pathogens, including ''Streptococcus pneumoniae,'' methicillin-resistant ''Staphylococcus aureus'' (MRSA), group A ''Streptococcus'' (GAS), and vancomycin-resistant ''Enterococcus'' (VRE) both ''
in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology a ...
'' and in a mouse infection model.


See also

*
Ionophore In chemistry, an ionophore () is a chemical species that reversibly binds ions. Many ionophores are lipid-soluble entities that transport ions across the cell membrane. Ionophores catalyze ion transport across hydrophobic membranes, such as liq ...


References

{{Reflist Quinolinols Chloroarenes