The study was terminated due to a lack of improvement in clinical efficacy outcomes.

A Phase 1 study in subjects with LR-MDS to assess the safety and tolerability of JSP191 as a second-line therapy.

An open-label, single-arm, dose-escalation study designed to determine the potential safety, efficacy, maximum tolerated dose (MTD) or optimal biologic dose (OBD), and recommended phase 2 dose (RP2D) of JSP191 (briquilimab) monotherapy for LR-MDS subjects with documented cytopenia (red blood cell-transfusion dependent, thrombocytopenia, and/or neutropenia).

Inclusion Criteria:

• Age ≥ 18 years
• MDS with IPSS-R very low, low, or intermediate risk features
• Symptomatic cytopenias
• Women of childbearing potential (WOCBP) must agree to use an oral or implanted contraceptive, a double-barrier method of birth control, or an intrauterine device upon enrollment and through 3 months after receiving the last dose of JSP191
• Women not of childbearing potential must be post-menopausal (no menstrual period for a minimum of 12 months) or surgically sterilized and have a negative serum pregnancy test upon study entry
• Male subjects must be surgically sterile or willing to use contraception upon enrollment and through 3 months after receiving the last dose of JSP191
• Must be willing and able to provide informed consent

Exclusion Criteria:

• Anemia secondary to iron deficiency, vitamin B12 deficiency, or folate deficiency
• Prior allogeneic or autologous stem cell transplant
• Known history of human immunodeficiency virus (HIV) (no laboratory testing is required), or active infection with hepatitis B or hepatitis C
• Pregnant women or women who are nursing and do not wish to discontinue breastfeeding
• Any other medical condition that, in the opinion of the Investigator, could pose a significant safety risk to the subject or jeopardize the integrity of the study
• Subjects who, in the opinion of the Investigator, may not be able to comply with the requirements of the study