Trial Outcomes & Findings for A Study of the Safety and Efficacy of SP-624 in the Treatment of Adults With Major Depressive Disorder (NCT NCT04479852)

Last Updated: 2025-06-12

Results Overview

The Montgomery Asberg Depression rating scale is a 10-item scale used to assess the severity of depression. Individual items are scored on a 7-point scale (0 to 6). The total score is the sum of individual items, ranging from 0 to 60; where a higher score indicates more depression.

Recruitment status

COMPLETED

Study phase

PHASE2

Target enrollment

319 participants

Primary outcome timeframe

Baseline to Week 4

Results posted on

2025-06-12

Participant Flow

Participant milestones

Participant milestones
Measure	SP-624 Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo Daily oral capsule Placebo: Oral capsule
Overall Study STARTED	163	156
Overall Study Safety Population	161	156
Overall Study COMPLETED	133	130
Overall Study NOT COMPLETED	30	26

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

A Study of the Safety and Efficacy of SP-624 in the Treatment of Adults With Major Depressive Disorder

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	SP-624 n=161 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=156 Participants Daily oral capsule Placebo: Oral capsule	Total n=317 Participants Total of all reporting groups
Age, Categorical <=18 years	2 Participants n=5 Participants	1 Participants n=7 Participants	3 Participants n=5 Participants
Age, Categorical Between 18 and 65 years	156 Participants n=5 Participants	154 Participants n=7 Participants	310 Participants n=5 Participants
Age, Categorical >=65 years	3 Participants n=5 Participants	1 Participants n=7 Participants	4 Participants n=5 Participants
Sex: Female, Male Female	101 Participants n=5 Participants	110 Participants n=7 Participants	211 Participants n=5 Participants
Sex: Female, Male Male	60 Participants n=5 Participants	46 Participants n=7 Participants	106 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	16 Participants n=5 Participants	21 Participants n=7 Participants	37 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	142 Participants n=5 Participants	135 Participants n=7 Participants	277 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	3 Participants n=5 Participants	0 Participants n=7 Participants	3 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	2 Participants n=5 Participants	1 Participants n=7 Participants	3 Participants n=5 Participants
Race (NIH/OMB) Asian	6 Participants n=5 Participants	10 Participants n=7 Participants	16 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	1 Participants n=5 Participants	1 Participants n=7 Participants	2 Participants n=5 Participants
Race (NIH/OMB) Black or African American	39 Participants n=5 Participants	32 Participants n=7 Participants	71 Participants n=5 Participants
Race (NIH/OMB) White	108 Participants n=5 Participants	107 Participants n=7 Participants	215 Participants n=5 Participants
Race (NIH/OMB) More than one race	5 Participants n=5 Participants	5 Participants n=7 Participants	10 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Region of Enrollment United States	161 Participants n=5 Participants	156 Participants n=7 Participants	317 Participants n=5 Participants

PRIMARY outcome

Timeframe: Baseline to Week 4

Population: Modified Intent To Treat population - all subjects who are randomized to receive treatment, receive at least one dose of study drug, and have a Baseline and at least one post-dose efficacy assessment.

Outcome measures

Outcome measures
Measure	SP-624 n=132 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=125 Participants Daily oral capsule Placebo: Oral capsule
Change From Baseline to Week 4 in Montgomery Asberg Depression Rating Scale (MADRS) Total Score	-12.6 Score on a scale Standard Error 0.83	-10.8 Score on a scale Standard Error 0.84

SECONDARY outcome

Timeframe: Baseline to Week 4

The CGI-S is a 7-point scale to rate the severity of the participant's illness at the time of assessment, relative to the clinician's past experience with participants who have the same diagnosis. A score of 1 represents "normal" and 7 represents "most extremely ill".

Outcome measures

Outcome measures
Measure	SP-624 n=132 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=125 Participants Daily oral capsule Placebo: Oral capsule
Change From Baseline to Week 4 in Clinical Global Impression - Severity (CGI-S) Total Score	-1.2 Score on a scale Standard Error 0.10	-0.9 Score on a scale Standard Error 0.10

SECONDARY outcome

Timeframe: Baseline to Week 4

The 17-item Hamilton Depression rating scale is used to assess the severity of depression. Individual items are scored on either a 3-point (0 to 2) or a 5-point scale (0 to 4), with 0=No difficulty/absent and 4=most severe. The total score is the sum of individual items, ranging from 0 to 52; where a higher score indicates more depression.

Outcome measures

Outcome measures
Measure	SP-624 n=132 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=125 Participants Daily oral capsule Placebo: Oral capsule
Change From Baseline to Week 4 in the 17-item Hamilton Depression Rating Scale (HAM D-17) Total Score	-8.3 Score on a scale Standard Error 0.56	-7.1 Score on a scale Standard Error 0.57

SECONDARY outcome

Timeframe: Baseline to Week 4

The Sheehan Disability Scale is a 3-part scale that measures the degree of disruption on work, social, and family life using an 11-point scale where 0 represents "no disruption" and 10 represents "extreme disruption". Each item (work, social, and family life) can have a score of 0-10. A total global functioning impairment score can be utilized by summing the scores from work, social, and family life scales for a value range from 0 to 30, where a higher score represents a worse outcome, i.e., more disruption on work, social, and family life. In addition to the 11-point scale, participants are asked to indicate the number of days in the past week that were "lost" and numbers of days that were "unproductive". The results of these questions have a range from 0 to 7 and are not included in the overall scale total.

Outcome measures

Outcome measures
Measure	SP-624 n=131 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=124 Participants Daily oral capsule Placebo: Oral capsule
Change From Baseline to Week 4 in the Sheehan Disability Scale (SDS)	-5.6 Score on a scale Standard Error 0.52	-4.6 Score on a scale Standard Error 0.54

SECONDARY outcome

Timeframe: Baseline to Week 4

The Quick Inventory of Depressive Symptomology - Self Report (QIDS-SR), is a 16 item self-reported scale where each item has a 4-point scale where 0 represents least impact scores while 3 represents greatest impact scores. Some questions are linked such that the highest score in a group of questions is entered once. For example, there are 4 questions related to sleep and the highest score on any of the 4 sleep items is entered once. The total score ranges from 0 to 27 where a higher score indicates more depression.

Outcome measures

Outcome measures
Measure	SP-624 n=131 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=124 Participants Daily oral capsule Placebo: Oral capsule
Change From Baseline to Week 4 in the Quick Inventory of Depressive Symptomology - Self Report (QIDS-SR)	-5.0 Score on a scale Standard Error 0.39	-4.1 Score on a scale Standard Error 0.40

SECONDARY outcome

Timeframe: Baseline to Week 4

The Quality of Life Enjoyment and Satisfaction Questionnaire - Short Form (Q-LES-Q-SF) is a 16 item satisfaction scale where each item has a 5-point scale. A score of 1 represents "very poor satisfaction", while a score of 5 represents "very good satisfaction". Only the first 14 items are summed for a total score that ranges from 14 to 70, where a lower score represents a worse outcome.

Outcome measures

Outcome measures
Measure	SP-624 n=131 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=124 Participants Daily oral capsule Placebo: Oral capsule
Change From Baseline to Week 4 in the Quality of Life Enjoyment and Satisfaction Questionnaire - Short Form (Q-LES-Q-SF)	9.5 Score on a scale Standard Error 1.03	7.8 Score on a scale Standard Error 1.06

POST_HOC outcome

Timeframe: Baseline to Week 4

Outcome measures

Outcome measures
Measure	SP-624 n=84 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=86 Participants Daily oral capsule Placebo: Oral capsule
Female Subjects Change From Baseline Montgomery Asberg Depression Rating Scale Score at Week 4	-13.4 Score on a scale Standard Error 1.05	-9.4 Score on a scale Standard Error 1.02

POST_HOC outcome

Timeframe: Baseline to Week 4

Outcome measures

Outcome measures
Measure	SP-624 n=84 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=86 Participants Daily oral capsule Placebo: Oral capsule
Female Change From Baseline to Week 4 in Clinical Global Impression - Severity (CGI-S) Total Score	-1.2 Score on a scale Standard Error 0.12	-0.8 Score on a scale Standard Error 0.11

POST_HOC outcome

Timeframe: Baseline to Week 4

Outcome measures

Outcome measures
Measure	SP-624 n=48 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=39 Participants Daily oral capsule Placebo: Oral capsule
Male Subjects Change From Baseline Montgomery Asberg Depression Rating Scale Score at Week 4	-11.3 Score on a scale Standard Error 1.21	-14.0 Score on a scale Standard Error 1.35

POST_HOC outcome

Timeframe: Baseline to Week 4

Outcome measures

Outcome measures
Measure	SP-624 n=48 Participants Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=39 Participants Daily oral capsule Placebo: Oral capsule
Male Change From Baseline to Week 4 in Clinical Global Impression - Severity (CGI-S) Total Score	-1.0 Score on a scale Standard Error 0.15	-1.2 Score on a scale Standard Error 0.16

Adverse Events

SP-624

Serious events: 0 serious events

Other events: 35 other events

Deaths: 0 deaths

Placebo

Serious events: 2 serious events

Other events: 36 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	SP-624 n=161 participants at risk Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=156 participants at risk Daily oral capsule Placebo: Oral capsule
Injury, poisoning and procedural complications Accidental Overdose	0.00% 0/161 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	0.64% 1/156 • Number of events 1 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.
Gastrointestinal disorders Gastrointestinal hemorrhage	0.00% 0/161 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	0.64% 1/156 • Number of events 1 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.

Other adverse events

Other adverse events
Measure	SP-624 n=161 participants at risk Daily oral capsule, 20 mg/day SP-624: Oral capsule	Placebo n=156 participants at risk Daily oral capsule Placebo: Oral capsule
Nervous system disorders Headache	8.1% 13/161 • Number of events 14 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	11.5% 18/156 • Number of events 21 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.
Gastrointestinal disorders Nausea	5.6% 9/161 • Number of events 9 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	8.3% 13/156 • Number of events 14 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.
Gastrointestinal disorders Diarrhea	5.6% 9/161 • Number of events 9 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	4.5% 7/156 • Number of events 8 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.
Psychiatric disorders Anxiety	2.5% 4/161 • Number of events 4 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	0.64% 1/156 • Number of events 2 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.
Nervous system disorders Dizziness	2.5% 4/161 • Number of events 4 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	5.8% 9/156 • Number of events 9 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.
Nervous system disorders Somnolence	2.5% 4/161 • Number of events 4 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.	1.3% 2/156 • Number of events 2 • Consent through 2 week follow up, up to 10 weeks (up to 28 day screening period, 4 week treatment period, and 2 week follow up period) Adverse events spontaneously reported by the subject and/or in response to an open question from the study personnel (i.e., how are you feeling?) or revealed by observation were recorded during the study at the investigational site.

Additional Information

Greg Rigdon, PhD

Sirtsei Pharmaceuticals

Phone: +1 919-949-6862

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place

Restriction type: OTHER