Inclusion Criteria:  Participant has signed an ICF prior to any study-specific procedures being performed. Participant has a diagnosis of Borderline Personality Disorder, per DSM-5 criteria, as confirmed on the MINI, and ≥ 16 AAPI-CR total score. Participant is in good physical health, and, in the opinion of the investigator, is a suitable candidate for treatment with monthly supportive psychotherapy. Participant is 18 to 65 years old. For participants already receiving psychotherapy, including Dialectical Behavioral Therapy (DBT), they must continue their regular course of treatment for the duration of the current study.  Exclusion Criteria:  Participant is pregnant, breast-feeding, or planning to become pregnant. A history or presence of a clinically significant hepatic, renal, gastrointestinal, cardiovascular, endocrine, respiratory, immunologic, hematologic, dermatologic, or neurologic abnormality, which in the opinion of the investigator may impact participant safety or study results. Participant has a history of any psychiatric condition other than BPD, which in the opinion of the investigator is primary, or any other psychiatric or neurologic disorder or symptom that could pose undue risk to the participant or compromise the study. Any participant who represents an acute suicidal risk in the opinion of the investigator, as defined by a "yes" response to suicidal ideation on questions 4 or 5, or answer "yes" to suicidal behavior questions on the CSSR-S within 90 days of screening. Any participant who represents an acute homicidal risk in the opinion of the investigator. Moderate or severe substance use disorder within 90 days prior to screen, according to DSM-5 criteria that in the opinion of the investigator could pose undue risk to the participant, or compromise the study. Any condition that, in the opinion of the investigator, makes the participant unsuitable for the study. Participants who require ongoing treatment with typical antipsychotics.