A randomized, double-blind, placebo- and active comparator-controlled, crossover trial to examine the effect of multiple doses of CVL-865 on panic symptoms induced by carbon dioxide inhalation in healthy subjects

CVL-865 (formerly known as PF-06372865) is a potent ligand of the allosteric
benzodiazepine (BZD) site of the *-aminobutyric acid type A (GABAA)
receptor, which is being developed for the treatment of neurological and
neuropsychiatric disorders. CVL-865 has the potential to retain highly
effective anxiolytic activity through *2 and *3 subunit-containing GABAA
receptors, which are thought to mediate the anxiolytic effects of BZDs without
the BZD-associated adverse effects that are mediated via the GABAA *1 subunits.
The aim of this trial is to evaluate the anxiolytic effects of multiple doses
of CVL-865 using an experimental medicine model of carbon dioxide (CO2)
inhalation that is associated with symptoms of anxiety/panic in healthy
subjects and is known to be sensitive to the effects of marketed anxiolytic
BZDs.

Primary:
To investigate if CVL-865 decreases subjective anxiety symptoms elicited by a
35% CO2 inhalation challenge.

Secondary:
To investigate if CVL-865 decreases subjective fear symptoms elicited by a 35%
CO2 inhalation challenge.
To investigate if CVL-865 modulates the physiological responses elicited by a
35% CO2 inhalation challenge.
To evaluate the safety and tolerability of CVL-865 following multiple oral
doses.
To evaluate the plasma exposure of CVL-865 (and alprazolam, if appropriate)
following multiple oral doses.
To evaluate the PD of CVL-865 following multiple oral doses in healthy subjects
using NeuroCart assessments.

This is a 3-cohort, randomized, double-blind, sponsor-open, placebo- and
active-controlled, crossover trial in which the pharmacodynamic (PD) effect of
multiple doses of CVL-865 and alprazolam will be examined in separate cohorts
of 18 subjects
each. The trial will be conducted as a 2-period, 2-sequence crossover design in
each cohort comparing high-dose CVL-865 (25 mg twice daily [BID]), low-dose
CVL-865 (7.5 mg BID), and alprazolam (1 mg BID) against placebo. Within each of
these cohorts, the subjects will be randomized equally to 1 of 2 treatment
sequences as shown in Table 2 of the protocol.

Test:
CVL-865 7.5 mg (BID)
CVL-865 25 mg (BID)
Alprazolam with extended release 1 mg (BID)

CVL-865
CVL-865 is not expected to provide any clinical benefit to healthy subjects.
The trial is designed primarily to generate preliminary efficacy, safety,
tolerability, and pharmacokinetic (PK) data which will inform further clinical
development for the treatment of anxiety disorders. There are no important
identified risks for CVL-865. Fetal toxicity, bone marrow suppression, and
decrease in peripheral hematologic parameters are important potential risks
identified nonclinically; however, these risks will be minimized during the
trial by monitoring of hematologic parameters and requiring the use of
appropriate contraception and regular pregnancy testing. More detailed
information about the known and expected benefits and risks and reasonably
expected AEs of CVL-865 are found in the Investigator*s Brochure.

Alprazolam
The BZD alprazolam is a non-selective GABAA PAM and is indicated for the
short-term treatment of moderate or severe anxiety states and anxiety
associated with depression. The most frequently reported side effects of
alprazolam include drowsiness, tiredness, sedation, dizziness, cognitive
dysfunction (including memory impairment), constipation, depression, difficulty
in urinating, speech disorder, headache, menstrual disease, nervousness, skin
rash, tremor, weight gain, weight loss, anxiety, blurred vision, diarrhea,
insomnia, decreased libido, increased appetite, irritability, and decreased
appetite. In addition, BZDs are associated with a risk of tolerance and
dependence following chronic
use. As the subjective anxiogenic effects elicited by the 35% CO2 double breath
inhalation challenge were previously shown to be decreased by alprazolam 1 mg
BID (Salvadore et al, 2019), it will be used as active comparator to facilitate
the interpretation of the PD effects of CVL-865. GABAA related PD effects, as
well as adverse effects will be monitored using NeuroCart, safety measures, and
AE reporting as indicated in the
schedule of assessments. Administration of alprazolam over a period of 8 days
is not expected to induce dependence in the selected trial population.

Carbon Dioxide Inhalation Challenge Model
The acute inhalation of 35% CO2 has been developed and validated as a reliable
challenge model to induce an acute panic reaction that adequately resembles
panic attacks phenomenologically. Both CO2 and O2 are harmless physiological
substances that are
inhaled according to a standardized challenge protocol that has been developed
by Maastricht University. Numerous trials in several hundred healthy volunteers
and patients suffering from panic disorder, social anxiety disorder,
post-traumatic stress disorder, and major depressive disorder have been
conducted according to this protocol over the past 30 years. In the majority of
these trials, a mixture of 35% CO2/65% O2 had been administered as either
single or double vital capacity inhalation. To our knowledge in all performed
trials, neither acute nor chronic AEs have been reported and no SAEs have
occurred. Evidence from prospective trials point out that healthy volunteers
who underwent 35% CO2 inhalation were not at greater risk to develop panic
disorder in the years following the challenge. To ensure subject safety for the
current trial, absolute and relative contra-indications are harmonized with
previous protocols and are incorporated into the inclusion and exclusion
criteria of the protocol. Details about the 35% CO2 double-breath inhalation
procedure, continuous blood pressure, heart rate, and respiratory rate
measurement, will be provided in a separate manual attached to this protocol.

Upon arrival, all subjects are required to complete a questionnaire related to
the presence of COVID-19 symptoms and/or contact with individuals diagnosed
with COVID-19. In addition, a temperature check will be performed. Despite
these measures, it cannot be ruled out for certain that an asymptomatic
infected subject might undergo the CO2 challenge. Therefore, additional
measures regarding disinfection of the CO2 challenge set up will be taken and
will be added to the current SOP for performing the CO2 challenge. Staff
performing the CO2 challenge will be thoroughly trained on these updated
hygiene measures. First, all parts of the set-up that can be disinfected, such
as the flowmeter, will be disinfected and all parts that cannot will be
replaced after each use. This is described in the updated SOP. Second, subjects
should not exhale into the respiratory mask during the double-breath execution
as instructed before and during the challenge. However, if by a small chance,
this happens, the Microgard II filter inside the respiratory mask has a viral
filter efficacy of 99.995% tested on bacteriophages of approximately 30 nm. Per
current knowledge, the SARS-CoV-2 virus is approximately 80 to 160 nm in size,
thus, the filter will filter out the SARS-CoV-2 virus. This means that every
component distal to the filter can be regarded as sterile. Third, the demand
valve is 1-directional only, making it impossible to contaminate the gas
canister. Fourth, the CO2 sample line proximal to the filter that runs to the
capnograph is also 1-directional only, meaning the air is directed away from
the subject, which implies no virus loaded air can be inhaled by the subject.
Finally, to guarantee a well-ventilated environment, the room in which the CO2
challenge is being performed is equipped with mechanical ventilation, and doors
and windows will be kept open for a minimum of 30 minutes after performing each
challenge, to ventilate the room. Altogether, conducting the CO2 challenge is
considered safe under the condition that the extra safety measures related to
hygiene, as described in the updated SOP, are taken. The risk of transmission
of the SARS-CoV-2 virus by conducting the CO2 challenge during trial periods is
assessed as not being increased: all subjects staying in the clinic overnight
will be tested for SARS-CoV-2 infection and only subjects testing negative will
be included in the trial. Two different CO2 challenge set ups will be used; one
for the screening period and one for the trial periods. This ensures that the
set up for the trial periods will only be used by subjects who have tested
negative for infection with SARS-CoV2.