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Two oral agents with novel mechanisms of action in schizophrenia generated considerable audience interest after acing large phase 2 clinical trials presented at the virtual congress of the European College of Neuropsychopharmacology.
The two successful drugs moving on to definitive phase 3 studies after their performance at ECNP 2020 are KarXT, a proprietary combination of xanomeline and trospium chloride, and an inhibitor of glycine transporter 1 (Gly-T1) known for now as BI 425809.
Pimavanserin, an oral selective serotonin inverse agonist with a high affinity for 5-HT2A receptors and low affinity for 5-HT2C receptors, has taken a more convoluted path through the developmental pipeline for schizophrenia. It recently failed to outperform placebo as adjunctive treatment for schizophrenia on the primary endpoint of improvement in Positive And Negative Syndrome Scale (PANSS) total score in the 6-week, phase 3 ENHANCE (Efficacy and Safety of Adjunctive Pimavanserin for the Treatment of Schizophrenia) study. The drug did, however, show significant benefit on secondary endpoints involving negative symptoms.
And in the 400-patient, 26-week, placebo-controlled, phase 2 ADVANCE trial, adjunctive pimavanserin was positive for the primary endpoint of improvement in the Negative Symptom Assessment-16 (NSA-16) score. A phase 3 program evaluating the drug specifically for negative symptoms is underway.
Another novel therapy, an investigational selective estrogen receptor beta agonist, proved reassuringly safe but completely ineffective in men with schizophrenia in a study presented at ECNP 2020.
“The results, unfortunately, were disappointing. We saw no signal on cognition, no change on brain imaging with fMRI, and no improvement in negative symptoms or PANSS total score,” reported Alan Breier, MD, professor and vice chair of the department of psychiatry at Indiana University in Indianapolis.
Broad agreement exists that current antipsychotics targeting D2 dopamine and serotonin receptors in schizophrenia leave much to be desired. They’re ineffective for two of the three major symptom categories that define schizophrenia: cognitive impairment and negative symptoms, such as apathy and social withdrawal. And even for the current antipsychotics’ forte – treatment of positive symptoms, including hallucinations and delusions – effectiveness is often only modest to moderate and accompanied by limiting side effects.
KarXT
KarXT combines xanomeline, a selective M1/M4 muscarinic receptor agonist exclusively licensed from Lilly to Karuna Therapeutics, with trospium chloride, a muscarinic antagonist approved for more than a decade in the United States and Europe for treatment of overactive bladder. Xanomeline was synthesized in the 1990s. It showed promising evidence of antipsychotic efficacy in schizophrenia and Alzheimer’s disease in yearlong clinical trials totaling more than 800 patients, but interest in further developing the drug cooled because of limiting GI and other cholinergic adverse events. KarXT, Karuna’s lead product candidate, is designed to maintain the efficacy of xanomeline while trospium, which doesn’t cross the blood-brain barrier, cancels out its side effects, explained Stephen Brannan, MD, a psychiatrist and chief medical officer at the company.
He presented the results of the phase 2 study, a multicenter, randomized, double-blind, placebo-controlled, 5-week trial conducted with 182 schizophrenia inpatients experiencing an acute psychotic exacerbation. All other antipsychotics were washed out before randomization to KarXT at 50 mg xanomeline/20 mg trospium twice daily, titrated to 100/20 twice daily on days 3-7 and 100/20 b.i.d. thereafter, with an optional increase to 125/30 twice daily.
The primary study endpoint was change from baseline to week 5 in PANSS total score. The results were positive at the P < .0001 level, with a mean 17.4-point reduction in the KarXT group, compared with a 5.9-point improvement in placebo-treated controls. The between-group difference was significant by the first assessment at week 2.
Four of five prespecified secondary endpoints were also positive in rapid and sustained fashion: improvement in the PANSS positive subscore, PANSS negative subscore, Marder PANSS negative subscore, and Clinical Global Impressions-Severity. The fifth secondary endpoint – the proportion of patients with a Clinical Global Impressions rating of 1 or 2, meaning normal or only mildly mentally ill – wasn’t significantly different with KarXT, compared with placebo, but Dr. Brannan shrugged that off.
“In hindsight, it was probably a little overly optimistic to think that after 5 weeks [patients with schizophrenia] would be either well or almost well,” he quipped.
An exploratory analysis of participants’ before-and-after scores on a battery of six cognitive tests showed an encouraging trend: Patients on KarXT performed numerically better than did controls on five of the six tests, albeit not significantly so. Moreover, in a further analysis stratified by baseline impairment, patients in the most impaired tertile showed a larger, statistically significant benefit in response to KarXT.
“We’re interested enough that we plan to continue to look at this in our upcoming larger and longer-term trials,” Dr. Brannan said.
As for safety and tolerability, he continued: “We were pleasantly surprised. We certainly see more side effects with KarXT than with placebo, but not by that much, and they’re much, much better than with xanomeline alone.”
The side effects, mostly cholinergic and anticholinergic, occurred 2-4 times more frequently than in controls. Notably, the rates of nausea, vomiting, and dry mouth – three of the five most common treatment-related adverse events in patients on KarXT – decreased over time to levels similar to placebo by week 5. In contrast, rates of constipation and dyspepsia remained stable over time. All side effects were mild to moderate, and none led to study discontinuation.
A key point was that the KarXT-related side effects were not the same ones that are commonly problematic and limiting with current antipsychotics. There was no weight gain or other metabolic changes, sleepiness or sedation, or extrapyramidal symptoms.
“These results show KarXT has the potential to offer patients a novel mechanism-of-action antipsychotic with a different efficacy and/or tolerability profile than current antipsychotic medications,” Dr. Brannan said.
BI 425809
BI 425809 is a once-daily oral inhibitor of glycine transporter 1 (Gly-T1) specifically designed to alleviate cognitive impairment in people with schizophrenia. Underactivity by the NMDA (N-methyl-D-aspartic acid) receptor has been implicated in this cognitive dysfunction. Glycine is an NMDA cotransmitter. By blocking glutamatergic presynaptic and astrocyte reuptake of glycine, BI 425809 results in increased glycine levels in the synaptic cleft, facilitating neurotransmission, explained W. Wolfgang Fleischhacker, MD, president of the Medical University of Innsbruck (Austria), where he is also professor of psychiatry.
He presented the results of a phase 2, randomized, double-blind, 11-country study in which 509 adults with stable schizophrenia on no more than two antipsychotics were placed on add-on BI 425809 at 2, 5, 10, or 25 mg once daily or placebo for 12 weeks.
The primary endpoint was change from baseline to 12 weeks in the MATRICS (Measurement and Treatment Research to Improve Cognition in Schizophrenia) Consensus Cognitive Battery (MCCB) score. The results were strongly positive, with patients on the two top doses of BI 425809 – 10 and 25 mg/day – showing roughly a 2-point greater improvement in MCCB overall composite T-score compared with controls. Dr. Fleischhacker drew attention to the high study completion rates in the various study arms, ranging from a low of 91% to 97.6% in the 25 mg/day group.
“That’s a very nice but also an unusual finding for a trial of this length,” he observed.
The high study completion rate was a reflection of the drug’s high-level tolerability. Indeed, the rate of adverse events leading to treatment discontinuation was 0% with BI 425809 at 10 mg/day, 2.4% at 25 mg/day, and identical at 2.4% with placebo. No increase was found in psychiatric adverse events such as suicidal ideation or behavior.
“This is a first very promising result,” Dr. Fleischhacker concluded. “Basically, this is the first study that has really shown in a convincing fashion an effect of any novel compound on cognitive impairment in people suffering from schizophrenia.”
A separate ongoing phase 2 study is evaluating BI 425809 in combination with adjunctive computerized cognitive training in an effort to increase cognitive stimulation. The company is awaiting those study results before designing its phase 3 program.
Pimavanserin
It has been a busy year for pimavanserin, with both successes and disappointments in clinical trials addressing a range of psychotic disorders, according to Dragana Bugarski-Kirola, MD, MBA, MSc, vice president for clinical development at Acadia Pharmaceuticals in San Diego.
At present, pimavanserin is Food and Drug Administration–approved as Nuplazid only for treatment of hallucinations and delusions associated with Parkinson’s disease psychosis. But in July 2020, on the strength of the positive results of the pivotal phase 3 HARMONY trial, Acadia filed an application with the FDA for marketing approval of the drug for treatment of dementia-related psychosis. In HARMONY, patients on placebo proved to be 2.8-fold more likely to experience a relapse of delusions or hallucinations than with pimavanserin.
A big recent disappointment was that pimavanserin failed to meet its primary endpoint in the phase 3 CLARITY I and CLARITY II trials as adjunctive therapy for major depressive disorder inadequately responsive to a selective serotonin reuptake inhibitor or serotonin norepinephrine reuptake inhibitor. The change in Hamilton Depression Rating Scale–17 scores in patients on the atypical antipsychotic wasn’t significantly better than with placebo. However, pimavanserin did outperform placebo on the secondary endpoint of Clinical Global Impression–Severity. Additional clinical trials of the drug for treatment of major depression are planned, Dr. Bugarski-Kirola said.
LY500307
Although schizophrenia is equally common in men and women, the disease has a later onset and more benign course in women. This suggests a possible protective effect of estrogen, and indeed, extensive literature supports the use of exogenous estrogen in schizophrenia, where it reduces relapses and improves cognitive impairment and negative symptoms.
“We have no other agents that do that,” noted Dr. Breier, also chief of the psychotic disorders program and director of the Prevention and Recovery Center at Indiana University.
What he considers the best-executed clinical trial of estradiol in schizophrenia, an 8-week, double-blind, randomized study of a 200-mcg estradiol patch or placebo in 200 women aged 19-46 on antipsychotics, was published last year (JAMA Psychiatry. 2019 Jul 31;76[10]:1-9).
The results were impressive. However, estrogen may not be a viable treatment for men and premenopausal women because of its side effects, including feminization, and increased thrombotic and malignancy risks.
This was the impetus for the placebo-controlled randomized trial of LY500307, a highly selective estrogen receptor beta agonist originally developed by Eli Lilly as a potential treatment for benign prostatic hypertrophy, for which it proved ineffective. In animal models, estrogen receptor beta is responsible for a range of effects, including enhanced cognition, social behavior, and an anxiolytic action, whereas the alpha receptor affects the sex organs, skeletal and metabolic homeostasis, and is responsible for estrogen’s problematic side effects.
All three doses studied in the phase 2 randomized trial, which included 94 men with schizophrenia, proved safe, well-tolerated – and ineffective.
“I think one potential conclusion one could consider from these data is that estrogen receptor alpha engagement may be necessary for the estrogenic therapeutics in schizophrenia,” Dr. Breier said.
He reported having no financial conflicts regarding the trial, funded by Indiana University. Outside the scope of the study, he serves as a consultant to Karuna Therapeutics, BioXcel, and Perception Neuroscience.
Dr. Fleischhacker serves as a consultant to Boehringer Ingelheim, which sponsored the phase 2 study of BI 425809, as well as to Angelini, Richter, and Recordati.
SOURCE: ECNP 2020, Session S.12.
Two oral agents with novel mechanisms of action in schizophrenia generated considerable audience interest after acing large phase 2 clinical trials presented at the virtual congress of the European College of Neuropsychopharmacology.
The two successful drugs moving on to definitive phase 3 studies after their performance at ECNP 2020 are KarXT, a proprietary combination of xanomeline and trospium chloride, and an inhibitor of glycine transporter 1 (Gly-T1) known for now as BI 425809.
Pimavanserin, an oral selective serotonin inverse agonist with a high affinity for 5-HT2A receptors and low affinity for 5-HT2C receptors, has taken a more convoluted path through the developmental pipeline for schizophrenia. It recently failed to outperform placebo as adjunctive treatment for schizophrenia on the primary endpoint of improvement in Positive And Negative Syndrome Scale (PANSS) total score in the 6-week, phase 3 ENHANCE (Efficacy and Safety of Adjunctive Pimavanserin for the Treatment of Schizophrenia) study. The drug did, however, show significant benefit on secondary endpoints involving negative symptoms.
And in the 400-patient, 26-week, placebo-controlled, phase 2 ADVANCE trial, adjunctive pimavanserin was positive for the primary endpoint of improvement in the Negative Symptom Assessment-16 (NSA-16) score. A phase 3 program evaluating the drug specifically for negative symptoms is underway.
Another novel therapy, an investigational selective estrogen receptor beta agonist, proved reassuringly safe but completely ineffective in men with schizophrenia in a study presented at ECNP 2020.
“The results, unfortunately, were disappointing. We saw no signal on cognition, no change on brain imaging with fMRI, and no improvement in negative symptoms or PANSS total score,” reported Alan Breier, MD, professor and vice chair of the department of psychiatry at Indiana University in Indianapolis.
Broad agreement exists that current antipsychotics targeting D2 dopamine and serotonin receptors in schizophrenia leave much to be desired. They’re ineffective for two of the three major symptom categories that define schizophrenia: cognitive impairment and negative symptoms, such as apathy and social withdrawal. And even for the current antipsychotics’ forte – treatment of positive symptoms, including hallucinations and delusions – effectiveness is often only modest to moderate and accompanied by limiting side effects.
KarXT
KarXT combines xanomeline, a selective M1/M4 muscarinic receptor agonist exclusively licensed from Lilly to Karuna Therapeutics, with trospium chloride, a muscarinic antagonist approved for more than a decade in the United States and Europe for treatment of overactive bladder. Xanomeline was synthesized in the 1990s. It showed promising evidence of antipsychotic efficacy in schizophrenia and Alzheimer’s disease in yearlong clinical trials totaling more than 800 patients, but interest in further developing the drug cooled because of limiting GI and other cholinergic adverse events. KarXT, Karuna’s lead product candidate, is designed to maintain the efficacy of xanomeline while trospium, which doesn’t cross the blood-brain barrier, cancels out its side effects, explained Stephen Brannan, MD, a psychiatrist and chief medical officer at the company.
He presented the results of the phase 2 study, a multicenter, randomized, double-blind, placebo-controlled, 5-week trial conducted with 182 schizophrenia inpatients experiencing an acute psychotic exacerbation. All other antipsychotics were washed out before randomization to KarXT at 50 mg xanomeline/20 mg trospium twice daily, titrated to 100/20 twice daily on days 3-7 and 100/20 b.i.d. thereafter, with an optional increase to 125/30 twice daily.
The primary study endpoint was change from baseline to week 5 in PANSS total score. The results were positive at the P < .0001 level, with a mean 17.4-point reduction in the KarXT group, compared with a 5.9-point improvement in placebo-treated controls. The between-group difference was significant by the first assessment at week 2.
Four of five prespecified secondary endpoints were also positive in rapid and sustained fashion: improvement in the PANSS positive subscore, PANSS negative subscore, Marder PANSS negative subscore, and Clinical Global Impressions-Severity. The fifth secondary endpoint – the proportion of patients with a Clinical Global Impressions rating of 1 or 2, meaning normal or only mildly mentally ill – wasn’t significantly different with KarXT, compared with placebo, but Dr. Brannan shrugged that off.
“In hindsight, it was probably a little overly optimistic to think that after 5 weeks [patients with schizophrenia] would be either well or almost well,” he quipped.
An exploratory analysis of participants’ before-and-after scores on a battery of six cognitive tests showed an encouraging trend: Patients on KarXT performed numerically better than did controls on five of the six tests, albeit not significantly so. Moreover, in a further analysis stratified by baseline impairment, patients in the most impaired tertile showed a larger, statistically significant benefit in response to KarXT.
“We’re interested enough that we plan to continue to look at this in our upcoming larger and longer-term trials,” Dr. Brannan said.
As for safety and tolerability, he continued: “We were pleasantly surprised. We certainly see more side effects with KarXT than with placebo, but not by that much, and they’re much, much better than with xanomeline alone.”
The side effects, mostly cholinergic and anticholinergic, occurred 2-4 times more frequently than in controls. Notably, the rates of nausea, vomiting, and dry mouth – three of the five most common treatment-related adverse events in patients on KarXT – decreased over time to levels similar to placebo by week 5. In contrast, rates of constipation and dyspepsia remained stable over time. All side effects were mild to moderate, and none led to study discontinuation.
A key point was that the KarXT-related side effects were not the same ones that are commonly problematic and limiting with current antipsychotics. There was no weight gain or other metabolic changes, sleepiness or sedation, or extrapyramidal symptoms.
“These results show KarXT has the potential to offer patients a novel mechanism-of-action antipsychotic with a different efficacy and/or tolerability profile than current antipsychotic medications,” Dr. Brannan said.
BI 425809
BI 425809 is a once-daily oral inhibitor of glycine transporter 1 (Gly-T1) specifically designed to alleviate cognitive impairment in people with schizophrenia. Underactivity by the NMDA (N-methyl-D-aspartic acid) receptor has been implicated in this cognitive dysfunction. Glycine is an NMDA cotransmitter. By blocking glutamatergic presynaptic and astrocyte reuptake of glycine, BI 425809 results in increased glycine levels in the synaptic cleft, facilitating neurotransmission, explained W. Wolfgang Fleischhacker, MD, president of the Medical University of Innsbruck (Austria), where he is also professor of psychiatry.
He presented the results of a phase 2, randomized, double-blind, 11-country study in which 509 adults with stable schizophrenia on no more than two antipsychotics were placed on add-on BI 425809 at 2, 5, 10, or 25 mg once daily or placebo for 12 weeks.
The primary endpoint was change from baseline to 12 weeks in the MATRICS (Measurement and Treatment Research to Improve Cognition in Schizophrenia) Consensus Cognitive Battery (MCCB) score. The results were strongly positive, with patients on the two top doses of BI 425809 – 10 and 25 mg/day – showing roughly a 2-point greater improvement in MCCB overall composite T-score compared with controls. Dr. Fleischhacker drew attention to the high study completion rates in the various study arms, ranging from a low of 91% to 97.6% in the 25 mg/day group.
“That’s a very nice but also an unusual finding for a trial of this length,” he observed.
The high study completion rate was a reflection of the drug’s high-level tolerability. Indeed, the rate of adverse events leading to treatment discontinuation was 0% with BI 425809 at 10 mg/day, 2.4% at 25 mg/day, and identical at 2.4% with placebo. No increase was found in psychiatric adverse events such as suicidal ideation or behavior.
“This is a first very promising result,” Dr. Fleischhacker concluded. “Basically, this is the first study that has really shown in a convincing fashion an effect of any novel compound on cognitive impairment in people suffering from schizophrenia.”
A separate ongoing phase 2 study is evaluating BI 425809 in combination with adjunctive computerized cognitive training in an effort to increase cognitive stimulation. The company is awaiting those study results before designing its phase 3 program.
Pimavanserin
It has been a busy year for pimavanserin, with both successes and disappointments in clinical trials addressing a range of psychotic disorders, according to Dragana Bugarski-Kirola, MD, MBA, MSc, vice president for clinical development at Acadia Pharmaceuticals in San Diego.
At present, pimavanserin is Food and Drug Administration–approved as Nuplazid only for treatment of hallucinations and delusions associated with Parkinson’s disease psychosis. But in July 2020, on the strength of the positive results of the pivotal phase 3 HARMONY trial, Acadia filed an application with the FDA for marketing approval of the drug for treatment of dementia-related psychosis. In HARMONY, patients on placebo proved to be 2.8-fold more likely to experience a relapse of delusions or hallucinations than with pimavanserin.
A big recent disappointment was that pimavanserin failed to meet its primary endpoint in the phase 3 CLARITY I and CLARITY II trials as adjunctive therapy for major depressive disorder inadequately responsive to a selective serotonin reuptake inhibitor or serotonin norepinephrine reuptake inhibitor. The change in Hamilton Depression Rating Scale–17 scores in patients on the atypical antipsychotic wasn’t significantly better than with placebo. However, pimavanserin did outperform placebo on the secondary endpoint of Clinical Global Impression–Severity. Additional clinical trials of the drug for treatment of major depression are planned, Dr. Bugarski-Kirola said.
LY500307
Although schizophrenia is equally common in men and women, the disease has a later onset and more benign course in women. This suggests a possible protective effect of estrogen, and indeed, extensive literature supports the use of exogenous estrogen in schizophrenia, where it reduces relapses and improves cognitive impairment and negative symptoms.
“We have no other agents that do that,” noted Dr. Breier, also chief of the psychotic disorders program and director of the Prevention and Recovery Center at Indiana University.
What he considers the best-executed clinical trial of estradiol in schizophrenia, an 8-week, double-blind, randomized study of a 200-mcg estradiol patch or placebo in 200 women aged 19-46 on antipsychotics, was published last year (JAMA Psychiatry. 2019 Jul 31;76[10]:1-9).
The results were impressive. However, estrogen may not be a viable treatment for men and premenopausal women because of its side effects, including feminization, and increased thrombotic and malignancy risks.
This was the impetus for the placebo-controlled randomized trial of LY500307, a highly selective estrogen receptor beta agonist originally developed by Eli Lilly as a potential treatment for benign prostatic hypertrophy, for which it proved ineffective. In animal models, estrogen receptor beta is responsible for a range of effects, including enhanced cognition, social behavior, and an anxiolytic action, whereas the alpha receptor affects the sex organs, skeletal and metabolic homeostasis, and is responsible for estrogen’s problematic side effects.
All three doses studied in the phase 2 randomized trial, which included 94 men with schizophrenia, proved safe, well-tolerated – and ineffective.
“I think one potential conclusion one could consider from these data is that estrogen receptor alpha engagement may be necessary for the estrogenic therapeutics in schizophrenia,” Dr. Breier said.
He reported having no financial conflicts regarding the trial, funded by Indiana University. Outside the scope of the study, he serves as a consultant to Karuna Therapeutics, BioXcel, and Perception Neuroscience.
Dr. Fleischhacker serves as a consultant to Boehringer Ingelheim, which sponsored the phase 2 study of BI 425809, as well as to Angelini, Richter, and Recordati.
SOURCE: ECNP 2020, Session S.12.
Two oral agents with novel mechanisms of action in schizophrenia generated considerable audience interest after acing large phase 2 clinical trials presented at the virtual congress of the European College of Neuropsychopharmacology.
The two successful drugs moving on to definitive phase 3 studies after their performance at ECNP 2020 are KarXT, a proprietary combination of xanomeline and trospium chloride, and an inhibitor of glycine transporter 1 (Gly-T1) known for now as BI 425809.
Pimavanserin, an oral selective serotonin inverse agonist with a high affinity for 5-HT2A receptors and low affinity for 5-HT2C receptors, has taken a more convoluted path through the developmental pipeline for schizophrenia. It recently failed to outperform placebo as adjunctive treatment for schizophrenia on the primary endpoint of improvement in Positive And Negative Syndrome Scale (PANSS) total score in the 6-week, phase 3 ENHANCE (Efficacy and Safety of Adjunctive Pimavanserin for the Treatment of Schizophrenia) study. The drug did, however, show significant benefit on secondary endpoints involving negative symptoms.
And in the 400-patient, 26-week, placebo-controlled, phase 2 ADVANCE trial, adjunctive pimavanserin was positive for the primary endpoint of improvement in the Negative Symptom Assessment-16 (NSA-16) score. A phase 3 program evaluating the drug specifically for negative symptoms is underway.
Another novel therapy, an investigational selective estrogen receptor beta agonist, proved reassuringly safe but completely ineffective in men with schizophrenia in a study presented at ECNP 2020.
“The results, unfortunately, were disappointing. We saw no signal on cognition, no change on brain imaging with fMRI, and no improvement in negative symptoms or PANSS total score,” reported Alan Breier, MD, professor and vice chair of the department of psychiatry at Indiana University in Indianapolis.
Broad agreement exists that current antipsychotics targeting D2 dopamine and serotonin receptors in schizophrenia leave much to be desired. They’re ineffective for two of the three major symptom categories that define schizophrenia: cognitive impairment and negative symptoms, such as apathy and social withdrawal. And even for the current antipsychotics’ forte – treatment of positive symptoms, including hallucinations and delusions – effectiveness is often only modest to moderate and accompanied by limiting side effects.
KarXT
KarXT combines xanomeline, a selective M1/M4 muscarinic receptor agonist exclusively licensed from Lilly to Karuna Therapeutics, with trospium chloride, a muscarinic antagonist approved for more than a decade in the United States and Europe for treatment of overactive bladder. Xanomeline was synthesized in the 1990s. It showed promising evidence of antipsychotic efficacy in schizophrenia and Alzheimer’s disease in yearlong clinical trials totaling more than 800 patients, but interest in further developing the drug cooled because of limiting GI and other cholinergic adverse events. KarXT, Karuna’s lead product candidate, is designed to maintain the efficacy of xanomeline while trospium, which doesn’t cross the blood-brain barrier, cancels out its side effects, explained Stephen Brannan, MD, a psychiatrist and chief medical officer at the company.
He presented the results of the phase 2 study, a multicenter, randomized, double-blind, placebo-controlled, 5-week trial conducted with 182 schizophrenia inpatients experiencing an acute psychotic exacerbation. All other antipsychotics were washed out before randomization to KarXT at 50 mg xanomeline/20 mg trospium twice daily, titrated to 100/20 twice daily on days 3-7 and 100/20 b.i.d. thereafter, with an optional increase to 125/30 twice daily.
The primary study endpoint was change from baseline to week 5 in PANSS total score. The results were positive at the P < .0001 level, with a mean 17.4-point reduction in the KarXT group, compared with a 5.9-point improvement in placebo-treated controls. The between-group difference was significant by the first assessment at week 2.
Four of five prespecified secondary endpoints were also positive in rapid and sustained fashion: improvement in the PANSS positive subscore, PANSS negative subscore, Marder PANSS negative subscore, and Clinical Global Impressions-Severity. The fifth secondary endpoint – the proportion of patients with a Clinical Global Impressions rating of 1 or 2, meaning normal or only mildly mentally ill – wasn’t significantly different with KarXT, compared with placebo, but Dr. Brannan shrugged that off.
“In hindsight, it was probably a little overly optimistic to think that after 5 weeks [patients with schizophrenia] would be either well or almost well,” he quipped.
An exploratory analysis of participants’ before-and-after scores on a battery of six cognitive tests showed an encouraging trend: Patients on KarXT performed numerically better than did controls on five of the six tests, albeit not significantly so. Moreover, in a further analysis stratified by baseline impairment, patients in the most impaired tertile showed a larger, statistically significant benefit in response to KarXT.
“We’re interested enough that we plan to continue to look at this in our upcoming larger and longer-term trials,” Dr. Brannan said.
As for safety and tolerability, he continued: “We were pleasantly surprised. We certainly see more side effects with KarXT than with placebo, but not by that much, and they’re much, much better than with xanomeline alone.”
The side effects, mostly cholinergic and anticholinergic, occurred 2-4 times more frequently than in controls. Notably, the rates of nausea, vomiting, and dry mouth – three of the five most common treatment-related adverse events in patients on KarXT – decreased over time to levels similar to placebo by week 5. In contrast, rates of constipation and dyspepsia remained stable over time. All side effects were mild to moderate, and none led to study discontinuation.
A key point was that the KarXT-related side effects were not the same ones that are commonly problematic and limiting with current antipsychotics. There was no weight gain or other metabolic changes, sleepiness or sedation, or extrapyramidal symptoms.
“These results show KarXT has the potential to offer patients a novel mechanism-of-action antipsychotic with a different efficacy and/or tolerability profile than current antipsychotic medications,” Dr. Brannan said.
BI 425809
BI 425809 is a once-daily oral inhibitor of glycine transporter 1 (Gly-T1) specifically designed to alleviate cognitive impairment in people with schizophrenia. Underactivity by the NMDA (N-methyl-D-aspartic acid) receptor has been implicated in this cognitive dysfunction. Glycine is an NMDA cotransmitter. By blocking glutamatergic presynaptic and astrocyte reuptake of glycine, BI 425809 results in increased glycine levels in the synaptic cleft, facilitating neurotransmission, explained W. Wolfgang Fleischhacker, MD, president of the Medical University of Innsbruck (Austria), where he is also professor of psychiatry.
He presented the results of a phase 2, randomized, double-blind, 11-country study in which 509 adults with stable schizophrenia on no more than two antipsychotics were placed on add-on BI 425809 at 2, 5, 10, or 25 mg once daily or placebo for 12 weeks.
The primary endpoint was change from baseline to 12 weeks in the MATRICS (Measurement and Treatment Research to Improve Cognition in Schizophrenia) Consensus Cognitive Battery (MCCB) score. The results were strongly positive, with patients on the two top doses of BI 425809 – 10 and 25 mg/day – showing roughly a 2-point greater improvement in MCCB overall composite T-score compared with controls. Dr. Fleischhacker drew attention to the high study completion rates in the various study arms, ranging from a low of 91% to 97.6% in the 25 mg/day group.
“That’s a very nice but also an unusual finding for a trial of this length,” he observed.
The high study completion rate was a reflection of the drug’s high-level tolerability. Indeed, the rate of adverse events leading to treatment discontinuation was 0% with BI 425809 at 10 mg/day, 2.4% at 25 mg/day, and identical at 2.4% with placebo. No increase was found in psychiatric adverse events such as suicidal ideation or behavior.
“This is a first very promising result,” Dr. Fleischhacker concluded. “Basically, this is the first study that has really shown in a convincing fashion an effect of any novel compound on cognitive impairment in people suffering from schizophrenia.”
A separate ongoing phase 2 study is evaluating BI 425809 in combination with adjunctive computerized cognitive training in an effort to increase cognitive stimulation. The company is awaiting those study results before designing its phase 3 program.
Pimavanserin
It has been a busy year for pimavanserin, with both successes and disappointments in clinical trials addressing a range of psychotic disorders, according to Dragana Bugarski-Kirola, MD, MBA, MSc, vice president for clinical development at Acadia Pharmaceuticals in San Diego.
At present, pimavanserin is Food and Drug Administration–approved as Nuplazid only for treatment of hallucinations and delusions associated with Parkinson’s disease psychosis. But in July 2020, on the strength of the positive results of the pivotal phase 3 HARMONY trial, Acadia filed an application with the FDA for marketing approval of the drug for treatment of dementia-related psychosis. In HARMONY, patients on placebo proved to be 2.8-fold more likely to experience a relapse of delusions or hallucinations than with pimavanserin.
A big recent disappointment was that pimavanserin failed to meet its primary endpoint in the phase 3 CLARITY I and CLARITY II trials as adjunctive therapy for major depressive disorder inadequately responsive to a selective serotonin reuptake inhibitor or serotonin norepinephrine reuptake inhibitor. The change in Hamilton Depression Rating Scale–17 scores in patients on the atypical antipsychotic wasn’t significantly better than with placebo. However, pimavanserin did outperform placebo on the secondary endpoint of Clinical Global Impression–Severity. Additional clinical trials of the drug for treatment of major depression are planned, Dr. Bugarski-Kirola said.
LY500307
Although schizophrenia is equally common in men and women, the disease has a later onset and more benign course in women. This suggests a possible protective effect of estrogen, and indeed, extensive literature supports the use of exogenous estrogen in schizophrenia, where it reduces relapses and improves cognitive impairment and negative symptoms.
“We have no other agents that do that,” noted Dr. Breier, also chief of the psychotic disorders program and director of the Prevention and Recovery Center at Indiana University.
What he considers the best-executed clinical trial of estradiol in schizophrenia, an 8-week, double-blind, randomized study of a 200-mcg estradiol patch or placebo in 200 women aged 19-46 on antipsychotics, was published last year (JAMA Psychiatry. 2019 Jul 31;76[10]:1-9).
The results were impressive. However, estrogen may not be a viable treatment for men and premenopausal women because of its side effects, including feminization, and increased thrombotic and malignancy risks.
This was the impetus for the placebo-controlled randomized trial of LY500307, a highly selective estrogen receptor beta agonist originally developed by Eli Lilly as a potential treatment for benign prostatic hypertrophy, for which it proved ineffective. In animal models, estrogen receptor beta is responsible for a range of effects, including enhanced cognition, social behavior, and an anxiolytic action, whereas the alpha receptor affects the sex organs, skeletal and metabolic homeostasis, and is responsible for estrogen’s problematic side effects.
All three doses studied in the phase 2 randomized trial, which included 94 men with schizophrenia, proved safe, well-tolerated – and ineffective.
“I think one potential conclusion one could consider from these data is that estrogen receptor alpha engagement may be necessary for the estrogenic therapeutics in schizophrenia,” Dr. Breier said.
He reported having no financial conflicts regarding the trial, funded by Indiana University. Outside the scope of the study, he serves as a consultant to Karuna Therapeutics, BioXcel, and Perception Neuroscience.
Dr. Fleischhacker serves as a consultant to Boehringer Ingelheim, which sponsored the phase 2 study of BI 425809, as well as to Angelini, Richter, and Recordati.
SOURCE: ECNP 2020, Session S.12.
FROM ECNP 2020