With one in 10 Americans over 65 currently living with symptomatic Alzheimers disease, you probably know someone affected by this disease. Worldwide, 50 million people live with symptomatic Alzheimers, making it the most common form of dementia. It commonly affects people over 65, but less than 4 percent of the estimated 5.7 million Americans affected have early-onset Alzheimers with symptoms beginning before age 65.
By 2050, nearly 14 million Americans are projected to suffer from this disease. Alzheimers is 6th leading cause of death in the US, making Alzheimers disease a top health concern. Unfortunately, there is no cure, but current medications and management strategies may improve symptoms, prolonging patient independence. In honor of November being Alzheimers Awareness month, we evaluated the current therapies, drugs in the pipeline and disease outlook.
Overview
Alzheimers disease is a degenerative brain disease that typically begins in late middle age or old age. Degeneration of brain cells, called neurons, cause the symptoms of progressive memory loss, impaired thinking, disorientation and mood and personality changes.
Risk factors: The greatest risk factors are old age, having a family history of Alzheimers and carrying a mutation in a certain gene called apolipoprotein E 4 (APOE4). Environmental and lifestyle factors, such as diet and exercise, also contribute to disease development.
The risk of Alzheimers doubles every five years after the age of 65, with nearly 1 in 3 people age 85 or older developing the disease. People with the APOE4 gene variant are thought to have an increased risk for developing late-onset Alzheimers, but thats not a steadfast rule: inheriting the gene variant does not mean the person will definitely get Alzheimers and some Alzheimers patients do not have the APOE4 gene variant.
Causes: Alzheimers develops as a result of a complex interaction between many risk factors, all resulting in neuron damage and death. The buildup of misfolded proteins, such as the tau protein and -amyloid, create the hallmark protein clumps called tangles and plaques seen in Alzheimers brains. While these protein clumps are thought to cause neuron death by blocking nerve cell communication and function, the exact relationship between the protein clump formation and neuron death is still unclear.
The four stages of Alzheimers: Based on the severity of dementia symptoms, Alzheimers can be characterized into four stages: preclinical, mild (early-stage), moderate (middle-stage) and severe (late-stage). The preclinical stage encompasses all the unseen changes in the brain, such as plaque accumulations, happening years before symptoms arise. Mild Alzheimers patients can still function independently, although they begin forgetting familiar words or locations of objects. As the dementia progresses to become moderate, the patient becomes more forgetful, has greater difficulty doing daily tasks and experiences personality and behavioral changes. At this stage, they may still remember significant life events. The moderate disease stage is the longest, often lasting for many years. Finally, severe Alzheimers patients can no longer respond to their environment, carry a conversation and control their movement or bowels. As the disease progresses, patients require an increasing level of care for daily activities.
Life expectancy: The earlier the diagnosis, the longer the life expectancy is: people diagnosed in their 60s to early 70s can live as long as 7 to 10 years, whereas those diagnosed in their 90s only average a 3-year life expectancy. Alzheimers patients live an average of four to eight years after their diagnosis, but can live as long as 20 years post-diagnosis. However, its difficult to link one disease to life expectancy, especially as you age, due to the many variables that influence life expectancy.
Cost: The cost burden of Alzheimers is as high as its prevalence: Alzheimers medications can range from $177 to $400 monthly, adding up to an annual prescription drugs estimated cost of $3,000. It will cost Americans an estimated $277 billion, including $186 billion in Medicare and Medicaid payments, to care for Alzheimers patients by the end of 2018. By 2050, this cost is projected to be more than $1.1 trillion, accounting for over four-fold increases in government spending through Medicare and Medicaid, as well as out-of-pocket expenses. Up to $7.9 trillion in medical and care costs could be saved by diagnosing earlier and more accurately.
Diagnosis Strategies
Although there is no specific test for Alzheimers disease, doctors use a variety of exams, imaging and lab testing to diagnose the disease.
Physical and neurological exams can test reflexes, coordination and memory. Brain imaging is used to rule out other physical abnormalities, such as tumors, stroke or other traumas, that can cause Alzheimers-like symptoms. Imaging can now be used to detect the specific changes that occur in the brains of living Alzheimers patients, not just in post-mortem analysis. Structural imaging techniques, such as magnetic resonance imaging (MRI) and computed tomography (CT), are used to rule out other physical injuries as well as assess Alzheimers-related brain shrinkage. Functional imaging, such as functional MRI (fMRI) and positron emission tomography (PET), can measure brain cell function by tracking the cells sugar and oxygen use.
Specific radioactive molecules, called radiotracers, can be used to detect -amyloid plaques via PET imaging. Three radiotracers have been approved by the U.S. Food and Drug Administration (FDA) since 2012: Amyvid (18F-florbetapir), Vizamyl (18F-flutametamol) and Neuraceq (18F-florbetaben).
Genetic testing can reveal if someone has a mutation, such as the APOE4 gene variant, that may increase their risk for developing Alzheimers. However, it is generally not recommended for Alzheimers diagnosis due to the lower accuracy, as many factors contribute to disease development. The exception is early-onset Alzheimers: Anyone with a family history of early Alzheimers can be screened for certain gene mutations, such as amyloid precursor protein (APP), presenilin-1 (PS-1) and presenilin-2 (PS-2).
Developing better diagnostic testing could facilitate earlier diagnoses, possibly leading to better outcomes. Future testing includes more sensitive mental ability exams and measuring key disease-associated proteins, called biomarkers, in the blood or spinal fluid.
Current Therapies
While there is no cure for Alzheimers disease, a handful of drugs have been approved by the FDA and shown to somewhat slow symptom progression. They can be broken down into two categories: cholinesterase inhibitors, which increase the amount of the neurotransmitter acetylcholine in the brain, resulting in more cell-to-cell communication; and NMDA receptor antagonists, which also alter how brain cells communicate.
Cholinesterase inhibitors include Eisais Aricept (donepezil) and Novartis Exelon (rivastigmine), both approved for all stages of Alzheimers, as well as Janssen Pharmaceuticals Razdyne (galantamine), which is approved for mild to moderate Alzheimers. Allerganhas two NMDA receptor antagonist-based drugs, Namenda (memantine) and the combination drug Namzaric (donepezil and memantine), which are both approved for moderate to severe Alzheimers. Antidepressants and anti-anxiety medications are sometimes prescribed as well to help control behavioral symptoms.
Unfortunately, these drugs can cause potentially severe side effects and arent overwhelmingly effective compared to placebo, although they have helped stave off mental decline for a while in some patients. However, the need for more effective drugs is clear.
Drug Pipeline
A variety of targeted therapies are currently being explored through clinical trials, including drugs against the tau protein, which forms distinctive tangles in Alzheimers brains; the -amyloid protein, which forms plaques in the Alzheimers brain; -secretase (BACE), an enzyme that cuts amyloid precursor protein (APP) into -amyloid; and the 5-HT2A serotonin receptor, which is involved in cognition and memory by mediating neurotransmitters, such as acetylcholine and glutamate.
The Alzheimers drug development market includes many large players, including Eli Lillywith six drugs (two in Phase 1, two in Phase 2 and two in Phase 3);Biogen with five drugs (two in Phase 1, one in Phase 2 and two in Phase 3); Roche, in collaboration with Genentech, AC Immune, and MorphoSys, with three drugs (two in Phase 2 and one in Phase 3); Eisai, in collaboration with Biogen, with one drug in Phase 3; and Eisai alone with one drug in Phase 2 (as of September 13, 2019).
As of September 13, 2019, there are over 670 active/recruiting/not yet recruiting clinical trials for Alzheimers listed on clinicaltrials.gov. According to a paper published in July 2019, there were 132 drugs in development for Alzheimers: 28 drugs in 42 Phase 3 trials, 74 drugs in 83 Phase 2 trials, and 30 drugs in 31 Phase 1 trials. The figure and legend below, taken from the July 2019 paper, shows all the drugs in clinical trials for Alzheimers as of February 2019.
UsAgainstAlzheimers released their 2019 Alzheimers Drug Pipeline report also in July 2019, where they focused on 98 late-stage Alzheimers drugs in development that could potentially reach the market in the next 5-10 years: 26 drugs in Phase 3 trials, and 72 drugs in Phase 2 trials. Their report shows that, despite some large Phase 3 failures this year, the Alzheimers pipeline is still robust.
The following analysis of some Alzheimers drugs in the pipeline will briefly discuss how each drug works and where it is in clinical trials. This information was up to date as of September 13, 2019. Any text in italics represents failed or terminated trials.
Phase 1
Biogen is exploring multiple antibody drugs against the -amyloid and tau proteins, including a Phase 1 trial studying the anti-tau antibody BIIB076 in 48 healthy and Alzheimers patients; a Phase 2 trial (TANGO) examining the anti-tau antibody BIIB092 (gosuranemab) in 528 early-stage Alzheimers patients; a Phase 2 trial in collaboration with Eisai studying the anti--amyloid antibody BAN2401 in 800 early-stage Alzheimers patients; and a Phase 3 trial (Clarity AD) studying BAN2401 in 1566 early Alzheimers patients.
Unfortunately, in March 2019, Biogen and its partner Eisai decided to end all studies involving another one of its anti--amyloid antibodies called aducanumab (previously called BIIB037), including their two Phase 3 trials (ENGAGE and EMERGE) each studying 1605 early-stage Alzheimers patients, a Phase 2 trial (EVOLVE) in 500 Alzheimers patients with mild cognitive impairment (MCI) or mild dementia due to Alzheimers, and a Phase 1 trial (PRIME) in 197 very mild (prodromal) or mild Alzheimers patients. The studies were stopped because they did not meet their clinical endpoints of slowing cognitive and functional impairment, not due to any safety concerns of the drug.
Eli Lilly is pursuing two chemical entities, a Tau Morphomer and an O-GlcNAcase Inhibitor, in Phase 1 clinical trials for Alzheimers.
Proclara Biosciencescombined a part of the human immunoglobulin protein with their unique protein technology, called General Amyloid Interaction Motif (GAIM), to create their fusion protein drug NPT088, which targets both -amyloid and tau proteins. Their Phase 1a safety trial showed that intravenous NPT088 is safe and well-tolerated in 40 healthy patients. Data from their Phase 1b dosing trial in Alzheimers patients is expected in 2019.
Cognition Therapeutics drug candidate CT1812 is a small molecule pill that disrupts -amyloid binding to a receptor called sigma-2 on brain cells, which is thought to prevent the proteins toxicity. CT1812 has been or is being studied in six clinical trials, including one recruiting Phase 1 trial with 18 mild to moderate Alzheimers patients, one recruiting Phase 1/2 trial with 21 mild to moderate Alzheimers patients, and one recruiting Phase 2 trial with 120 mild to moderate Alzheimers patients. CT1812 was well-tolerated and penetrated the brain very well in 80 healthy patients and 19 mild to moderate Alzheimers patients with mild to moderate side effects. Although the treated Alzheimers patients had lower levels of Alzheimers-related proteins (such as neurogranin and synaptotagmin-1, markers of synaptic damage) in their cerebrospinal fluid, they didnt show significantly different cognitive functioning compared with the placebo group after 28 days of treatment.
Samus Therapeuticsis developing a positron-emitting molecule, called 124I-PU-AD, that inhibits a certain protein complex called epichaperone complex, which reduced tau proteins in the brain, restored long-term memory and increased survival in preclinical animal models. 124I-PU-AD is also being used as a PET imaging agent to study the epichaperone complex in the brains of Alzheimers patients. They have completed an early Phase 1 trial in 5 Alzheimers and certain cancer patients to evaluate the molecules metabolism. Another Phase 1 study is currently recruiting 24 healthy volunteers to evaluate the safety and tolerance of the drug.
Janssen Research & Development is examining the ability of a radioactive PET imaging agent, called [18F]MNI-1020, to bind to the tau protein in Alzheimers patients. An early Phase 1 trial studied the safety and brain uptake efficacy of a single injection of the imaging agent in 15 Alzheimers and healthy age-matched patients. That study also compared the location of tau (using [18F]MNI-1020) and -amyloid (using Amyvid (florbetapir)) in patients with suspected Alzheimers.
Longeveron collects stem cells from healthy adult donors to create their own Longeveron mesenchymal stem cells (LMSCs), which have been shown to reduce inflammation and promote cell regeneration. Their Phase 1 clinical trial is currently recruiting 30 Alzheimers patients to evaluate the safety and efficacy of LMSCs.
Athira Pharmas small molecule drug NDX-1017 designed to restore lost or build new connections in the brain. Their Phase 1 trial is currently recruiting to evaluate the drugs safety in two parts, with Part A involving up to 56 healthy young and elderly participants and Part B involving 44 healthy, mild cognitive impairment or mild to moderate Alzheimers patients.
Cortexyme, Inc.is developing COR388, a first-in-class bacterial protease inhibitor that targets the bacteria Porphyromonas gingivalis, which is present in Alzheimers patients brains and cerebrospinal fluid and thought to contribute to the disease. Two completed Phase 1 trials have shown that COR388 is safe and well-tolerated in 58 healthy and nine Alzheimers patients. A Phase 2/3 trial is currently enrolling 573 mild to moderate Alzheimers patients to assess the drugs efficacy, safety, and tolerability.
Allergan was pursuing a small molecule drug called AGN-242071 that selectively targeted certain receptors in the brain, called muscarinic receptors, which may treat symptomatic cognitive deficits and behavioral symptoms in Alzheimers.
Unfortunately, Allergan decided to withdraw their Phase 1 trial evaluating the safety and tolerability of the drug prior to patient recruitment in November 2018.
Corium Internationalhas developed a novel delivery method for an approved drug, a once-weekly skin patch (the Corplex Donepezil Transdermal System) that delivers a sustained dose of donepezil. The patchs safety and drug profile were examined in multiple Phase 1 trials, which showed great skin tolerability and comparable dosages between the weekly patch and the currently prescribed daily donepezil pills. Corium is also developing a once-weekly skin patch to deliver memantine
Cognoptix has taken a different approach, developing an eye test called Sapphire II to catch and diagnose Alzheimers much earlier by detecting -amyloid deposits in their eyes. A fluorescent drug that binds to the -amyloid protein (Aftobetin-HCl) is administered to the eye as an ointment and binding is detected with the Sapphire II laser device. Their Phase 1 study determined the optimal dosing of the fluorescent drug in 15 participants and is currently recruiting 10 normal and 20 mild cognitive impairment (MCI) or mild Alzheimers patients for dose testing. If the dosing is optimal, then 30 more MCI and 30 more mild Alzheimers patients will be recruited, totaling 105 participants.
Phase 1/2
Ionis Pharmaceuticalsis collaborating with Biogen to study their antisense oligonucleotide drug IONIS-MAPTRx (also called BIIB080), which may reduce tau protein production and its accumulation in brain cells, in a Phase 1/2 trial in 44 mild Alzheimers patients.
QR Pharma, Inc.s small molecule drug Posiphen inhibits APP, tau and -synuclein (involved with Parkinsons disease) protein synthesis. They are currently recruiting 24 Alzheimers patients for their Phase 1/2 dosage study (DISCOVER).
Following their successful Phase 1 trial (SEAD) in 15 Alzheimers patients, Ausio Pharmaceuticalsbrought their estrogen receptor activating drug S-equol (also called AUS-131) to a Phase 1/2 trial (SEAD2), which is currently recruiting 40 Alzheimers patients to test the drugs tolerability and whether or not it affects cognitive abilities. Activating the estrogen receptors on mitochondria is thought to promote mitochondrial functioning, which could restore the reduced mitochondrial activity seen in Alzheimers patients. Less mitochondrial activity is thought to contribute to -amyloid protein build-up in the brain.
Nature Cell Co. is studying a fat cell-derived mesenchymal stem cell (MSC) therapy called AstroStem in an active Phase 1/2 study involving 21 mild to moderate Alzheimers patients.
Phase 2
Eli Lilly has two ongoing Phase 2 trials studying antibody drugs: one active trial (TRAILBLAZER-ALZ) evaluating the tolerability and efficacy of a humanized anti--amyloid antibody, called donanemab (LY3002813 or N3pG-A MAb), in 266 early symptomatic Alzheimers patients; and another currently recruiting trial evaluating the safety and efficacy of a humanized anti-tau antibody, called zagotenemab (LY3303560), in 285 early symptomatic Alzheimers patients.
Roche, in partnership with AC Immune, is studying crenezumab (RG7412), an anti--amyloid antibody drug that binds to -amyloid similar to Eli Lillys solanezumab. Crenezumab is being investigated in an active Phase 2 trial involving 252 non-symptomatic adults with a family history of Alzheimers who have a particular genetic mutation (autosomal-dominant PSEN1 E280A). Baseline data for 242 of the enrolled patients were presented at the Alzheimers Association International Conference in August 2019. Another not yet recruiting Phase 2 trial is in the works to study the effect of crenezumab on the longitudinal tau burden via PET imaging of 150 patients enrolled in the active Phase 2 trial (NCT01998841).
Crenezumab was being investigated in three Phase 3 trials: CREAD 1 evaluating the drugs safety and efficacy in 813 mild Alzheimers patients; CREAD 2 studying the drugs safety and efficacy in 750 mild Alzheimers patients; and an open-label extension trial (CREAD OLE) examining long-term drug treatment in 149 Alzheimers patients. Unfortunately, in January 2019, Roche discontinued all CREAD trials due to the interim analysis showing crenezumab was unlikely to meet the primary endpoint of improving cognition.
Genentech (a subsidiary of Roche) is partnering with AC Immune to develop the anti-tau antibody drug RO7105705 (also called RG6100 and MTAU9937A), which recognizes tau tangles and is meant to block their spread between cells. An active Phase 2 trial involving 457 prodromal to mild Alzheimers patients is studying the drugs safety and effect on cognitive function.
AbbVies humanized antibody drug ABBV-8E12, which targets the tau protein, is being evaluated for its safety and efficacy in an active Phase 2 trial involving 400 early-stage Alzheimers patients. An extension study to study the drugs long-term safety and tolerability is currently enrolling patients from the Phase 2 study (NCT02880956) by invitation.
Avid Radiopharmaceuticals, a wholly-owned subsidiary of Eli Lilly, is developing the PET imaging agent 18F-AV-1451 (also called Flortaucipir F 18 or F 18 T807), a molecule that binds to the tau protein, allowing researchers to study tau in living patients. There are multiple Phase 2 or Phase 2/3 trials studying the imaging agents safety and efficacy, with five Phase 2 trials currently recruiting or not yet recruiting: one to evaluate the agents safety and tau binding via PET imaging in 250 healthy, Alzheimers, traumatic brain injury and depression patients; one (ADRC proj 1) to compare tau tangles in the brain with cerebrospinal fluid CSF biomarkers and cognitive status in 80 Alzheimers patients; one (DIAN Project, AV ADAD) to study the presence of tau tangles in the brain and cognitive status in 130 adults; one to study the uptake and binding in 80 older HIV-positive adults with and without HIV-associated neurocognitive disorders and HIV-negative age-matched controls; and one (Protocol Z) to study tau and amyloid lesions in the brains of 80 APOE4+ adults with normal cognition or early-stage symptomatic Alzheimers.
Neurotrope Bioscience is developing bryostatin-1, a small molecule that activates protein kinase C (PKC), a protein that is important for learning and memory. This drug stimulates synapse repair and growth, activates -amyloid degrading enzymes and prevents tau tangle formation and neuron death. A Phase 2 trial evaluating the safety and efficacy of bryostatin-1 in 147 moderate to severe Alzheimers patients showed positive results: the lower (20 g) dose improved cognition and the ability to care for oneself. This prompted a second Phase 2 trial to study the drugs safety and efficacy at the lower dose in 108 moderately severe to severe Alzheimers patients.
Unfortunately, Neurotrope announced that the second Phase 2 trial did not show statistically significant improvement in memory, indicating it did not meet its primary endpoint of a change in the Severe Impairment Battery (SIB) test total score from baseline to week 13.
EIP Pharma is pursuing a small molecule called neflamapimod (VX-745) that inhibits an enzyme, called p38 MAPK, found in the neurons that is involved in inflammation and possibly -amyloid toxicity. Neflamapimod previously showed clinical activity in rheumatoid arthritis patients before being licensed to EIP Pharma. They are currently conducting a Phase 2b efficacy study (REVERSE-SD) in 161 participants with mild Alzheimers. A Phase 3 study is scheduled to start in the third quarter of 2020. Another Phase 2 trial is recruiting 40 Alzheimers patients to study neflamapimod on brain inflammation.
Actinogen Medicalis studying a drug called xanamem, which inhibits a cortisol-producing enzyme in the brain, ultimately blocking local production of cortisol, known as the stress hormone. While blood cortisol levels tend to rise with age, its particularly raised in patient with certain diseases, such as Alzheimers. Long-term high cortisol levels can be toxic to brain neurons, so preventing cortisol production in the brain may help slow cognitive decline and -amyloid plaque formation. After assessing xanamems safety and dosing in two Phase 1 trials, a Phase 2 trial (XanADu) assessed the drugs safety and efficacy in 186 early-stage Alzheimers patients.
Boehringer Ingelheims drug BI 425809 is a glycine transport inhibitor designed to regulate signaling in the brain that contributes to cognitive impairment. An active Phase 2 trial is studying the safety and effect on cognition of multiple dosages of the drug in 611 Alzheimers patients.
Neurocentriais developing a dietary supplement called MMFS, which contains a molecule called L-threonic acid magnesium salt (L-TAMS) that increases synapse density in portions of the brain needed for memory and executive functioning, such as the prefrontal cortex and hippocampus. Two previous studies showed improved cognition in mild to moderate Alzheimers patients, prompting the active Phase 2 trial that is recruiting 12 mild Alzheimers patients to examine the drugs safety and effect on cognition.
Alkahestis studying intravenously administered plasma-derived product called GRF6019, which is isolated from human plasma (a component of the blood) that has been shown to enhance neurogenesis and improve learning and memory in animals. Matching donor and patients blood types is not needed because the donor-specific antibodies (called immunoglobulins) are removed. A Phase 2 trial in 40 mild to moderate Alzheimers patients studied the safety and feasibility of GRF6019. Another Phase 2 trial is currently recruiting 20 severe Alzheimers patients to study the safety, tolerability, and cognitive benefits of the drug.
Suven Life Sciences drug SUVN-502 specifically inhibits a certain serotonin receptor (called 5-HT6), which is thought to improve cognition and memory. SUVN-502 in combination with donepezil and memantine was shown to increase the concentration of neurotransmitters, like acetylcholine. An active Phase 2 trial is testing the effect of this triple combination therapy on cognition in 563 moderate Alzheimers patients. An expanded access program is also available for eligible patients to receive the drug without being evaluated for safety and efficacy.
Neurim Pharmaceuticalsis taking a different approach by developing a drug, called piromelatine, that binds to and activates melatonin and serotonin receptors in the brain, promoting sleep and therefore neuroprotective effects. This drug was safe and promoted deeper and more REM sleep in a Phase 2 clinical trial in adults with insomnia. Given the link between sleep and Alzheimers, Neurim decided to study piromelatines effects on cognition in 500 mild Alzheimers patients in an active dose-ranging Phase 2 trial.
Eisai, in collaboration withPurdue Pharma, is studying their orexin receptor antagonist drug lemborexant in a Phase 2 trial involving 62 mild to moderate Alzheimers patients. The orexin receptor is involved in the regulation of sleep. Lemborexant binds to the orexin receptor, preventing orexin from binding, which should decrease wakefulness and promote falling and staying asleep naturally. Sleep, especially at appropriate hours, is troublesome for Alzheimers patients whose circadian rhythms tend to be dysregulated.
Phase 2/3
Novartis has partnered with Amgen and the Banner Alzheimer's Instituteto pursue Novartis drug umibacestat (CNP520), which inhibits BACE1, an enzyme involved in -amyloid production. After a successful Phase 2 trial safety study in 124 healthy elderly patients, there were two Phase 2/3 trials: one (Generation S1) to test the efficacy of CNP520 against an investigational immunotherapy drug (CAD106, a vaccine against a fragment of the -amyloid protein) in 481 non-symptomatic older patients with two copies of the APOE4 gene; and one (Generation S2) to test the drugs effect on cognition and underlying Alzheimers pathology in 1145 non-symptomatic older patients with at least one APOE4 allele and elevated brain -amyloid levels.
Unfortunately, both Phase 2/3 trials were discontinued in July 2019 due to worsening cognitive function seen during interim data analysis. As umibacestat was meant to delay the onset of symptoms, participants in the study will discontinue the investigational treatment and discuss further treatment options with their doctors.
TauRx Therapeutics drug TRx0237 (also called LMTX) is their second-generation tau protein aggregation inhibitor, which aims to both dissolve existing tau tangles and prevent new tangles from forming. Two previous Phase 3 clinical trials studied the safety and efficacy of high doses (150-250 mg/day) and a low dose control (8 mg/day) of the drug in 800 mild and 891 mild to moderate Alzheimers patients. Surprisingly, they found that the low dose was as beneficial as the higher doses, prompting a current Phase 2/3 trial (LUCIDITY) recruiting 375 early Alzheimers patients studying TRx0237 at low doses (8 and 16 mg/day). An expanded access program is also available to provide the drug to patients who have previously participated in a TauRx clinical trial but do not qualify for an ongoing trial.
Axsome Therapeutics is pursuing a treatment for agitation associated with Alzheimers and have been granted fast track status for their drug AXS-05, which combines dextromethorphan and bupropion. Dextromethorphan (called DM and commonly known as an over-the-counter cough suppressant) inhibits serotonin and norepinephrine transporters and the NMDA receptor at high doses. Bupropion increases the bioavailability of dextromethorphan and inhibits norepinephrine and dopamine reuptake. A Phase 2/3 trial (ADVANCE) is currently recruiting 435 Alzheimers patients to study the safety of AXS-05 and its effect on agitation.
Phase 3
Eli Lilly has a Phase 3 anti--amyloid antibody drug called solanezumab (LY2062430), which binds to soluble -amyloid monomers. The primary endpoints of trials involving this drug is to slow memory and cognitive decline. The drug is associated with 11 listed trials, including an active Phase 3 trial (A4) involving 1150 not yet symptomatic adults with evidence of amyloid plaque build-up in their brains, and a currently recruiting Phase 2/3 large collaboration trial (DIAN-TU) comparing solanezumab and gantenerumab in 490 non-symptomatic adults known to have an Alzheimers disease-causing mutation. This collaboration includes Eli Lilly, Roche, Avid Radiopharmaceuticals, Janssen, Alzheimers Association, National Institute on Aging (NIA), Accelerating Medicines Partnership (AMP), and Washington University School of Medicine.
Two Phase 3 trials (EXPEDITION and EXPEDITION 2) were completed previously and involved 1040 Alzheimers patients each. Although there was no difference in cognition between the treated and placebo groups, patients with mild Alzheimers did show slower cognitive decline compared to placebo, prompting further studies.
Unfortunately, the next three Phase 3 trials (EXPEDITION 3, EXPEDITION EXT and EXPEDITION PRO) were terminated due to lack of meeting primary endpoints, including slowing cognitive decline, and insufficient evidence that solanezumab would likely demonstrate a meaningful benefit to patients with prodromal Alzheimers.
Roche is currently investigating gantenerumab, an anti--amyloid antibody drug that binds and neutralizes -amyloid plaques. Gantenerumab, brought back after failing in previous clinical trials, is involved in four Phase 3 trials: two active trials studying the drugs effect on cognitive function in 799 prodromal and 389 mild Alzheimers patients; and two currently recruiting trials studying the drugs effect on cognition in 760 early Alzheimers patients each.
Eisai, in collaboration with Biogen, is studying their small molecule BACE1 inhibitor elenbecestat (also called E2609) in two Phase 3 trials (MISSION AD1 and MISSION AD2) currently recruiting 950 early-stage Alzheimers patients each. Inhibiting BACE1 is thought to interfere with -amyloid production.
Unfortunately, the companies announced that they were discontinuing their MISSION AD1 and AD2 Phase 3 trials on September 13, 2019. The decision was made based on results from a safety review that showed an unfavorable risk-benefit ratio of elenbecestat.
Avid Radiopharmaceuticals and Eli Lilly reported positive results earlier this year from their Phase 3 trial on the tau-binding PET imaging agent flortaucipir F 18 (18F-AV-1451 or Tau imaging agent) in Alzheimers patients. The trial met its two primary endpoints, successfully predicting both the disease-related role of tau in the brain and an Alzheimers diagnosis. PET imaging was performed on 156 end-of-life patients with cognition ranging from normal to dementia, with 67 of these patients being evaluated post-mortem. Flortaucipir could significantly detect Alzheimers-related changes in the brain, including both tau and -amyloid plaque densities. Being able to accurately image and diagnose Alzheimers patients is a critical component in understanding the disease and being able to manage it. There are currently 33 studies listed on clinicaltrials.gov for flortaucipir and Alzheimers.
AZTherapies, Inc. is studying the combination drug ALZT-OP1, which consists of the inhaled drug cromolyn and oral drug ibuprofen, both of which are anti-inflammatory. Inflammation in the brain is thought to trigger neuronal death, which causes progressive brain damage. Cromolyn was also shown to prevent -amyloid aggregation in one study. A Phase 3 trial (COGNITE) is currently studying the effect of this combination drug on cognitive decline in 620 early-stage Alzheimers patients.
ACADIA Pharmaceuticals drug pimavanserin (previously called ACP 103) is a selective serotonin inverse agonist (SSIA), meaning it both binds to serotonin receptor subtype 5-HT2A and blocks serotonin signaling. Following a few Phase 2 trials specifically in Alzheimers patients, there are currently three recruiting Phase 3 trials for a broader range of dementia patients: an efficacy study examining pimavanserins ability to prevent relapse of dementia-related psychosis symptoms in 356 dementia patients, a safety study in 300 patients with neurodegenerative disease, and an open-label extension study examining the drugs long-term safety in 300 patients with neurodegenerative disease who previously participated in another pimavanserin clinical trial by ACADIA.
Intra-Cellular Therapiesis developing lumateperone (ITI-007), a molecule that simultaneously affects serotonin, dopamine and glutamate signaling, which play important roles in multiple mental illnesses. Following a Phase 1b/2 study, they recruited 177 dementia patients, including Alzheimers patients, for a Phase 3 trial studying the safety and efficacy of the drug for reducing agitation.
However, the Phase 3 trial was terminated early due to interim data analysis indicating lumateperones lack of efficacy.
AVANIR Pharmaceuticals drug AVP-786 combines two approved drugs: deuterated dextromethorphan (d6-DM), which has better bioavailability and less side effects than regular DM, and an ultra-low dose of quinidine, which slows the metabolism of d6-DM by inhibiting an enzyme (CYP 2D6) that breaks down d6-DM. AVP-786 is a second-generation version of Nuedexta (formerly AVP-923), which is currently approved to treat pseudobulbar affect (PBA). Currently, there are four recruiting or active Phase 3 trials studying the safety and efficacy of AVP-786 in treating agitation in Alzheimers patients: one recruiting 412 Alzheimers patients with moderate to severe agitation worldwide, one active study involving 522 Alzheimers patients in the US, one completed study involving 410 Alzheimers patients in the US and a long-term extension study recruiting 700 patients who have completed previous clinical trials of AVP-786 by Avanir.
Otsuka Pharmaceutical Co.and Lundbeck are collaborating to develop brexpiprazole (brand name Rexulti) for treating agitation and behavioral symptoms in Alzheimers patients. Rexulti, which binds to and activates a particular dopamine receptor (D2), is currently FDA approved to treat schizophrenia and as an add-on treatment for major depression disorder. Two Phase 3 trials examining brexpiprazole at either fixed or flexible doses in a total of 703 Alzheimers patients showed reduced agitation compared to the placebo. They are currently recruiting for three Phase 3 trials: one evaluating the safety, efficacy, and tolerability in 225 Alzheimers patients with dementia-associated agitation in the US; one studying long-term treatment in 157 Alzheimers patients with dementia-associated agitation in Japan; and a 12-week extension study for 250 Alzheimers patients with dementia-associated agitation who were previously enrolled in other Otsuka trials studying brexpiprazole. They are also recruiting for a Phase 2/3 study in 407 Alzheimers patients with dementia-associated agitation in Japan.
Merck Sharp & Dohme Corp., a subsidiary of Merck, is studying their FDA approved drug suvorexant (previously called MK-4305, brand name Belsomra) to treat insomnia in Alzheimers patients. Currently approved for insomnia patients, the small molecule drug works by inhibiting the orexin receptor in the signaling system involved in wakefulness. Their Phase 3 trial studying suvorexants safety and efficacy at improving sleep in 285 Alzheimers patients and patients with insomnia concluded in October 2018, but results have not been posted yet.
Preclinical Candidates
A few companies are investigating drugs in the preclinical laboratory setting, hoping to gather promising data to bring their drugs to clinical trials.
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Alzheimer's Disease Insight Report: Current Therapies, Drug Pipeline and Outlook - BioSpace
