Inclusion Criteria:

• Confirmed low to intermediate-1 risk MDS.
• No more than 1 prior treatment for MDS.
• Exhibit at least one hematological cytopenias (anemia, neutropenia, or thrombocytopenia).
• Documentation of prior transfusion requirements.
• Have an Eastern Cooperative Oncology Group (ECOG) performance score of 0, 1, or 2.
• Be ≥18 and ≤70 years of age at time of signing the informed consent document (ICD).
• Is able to adhere to study visit schedule and all other protocol requirements.
• Is willing to practice a medically approved method of birth control during participation in the study (at least 12 months after the last infusion of rATG) (male and female patients).

Exclusion Criteria:

• Is pregnant or lactating.
• Has had prior treatment with any ATG.
• Has received any immunomodulatory or immunosuppressing agents (excluding steroids) <12 weeks prior to the first infusion of rATG.
• Has had a prior stem cell and/or other organ transplant.
• Has had a prior allergic reaction to rabbit proteins or excipients.
• Has any of the following subtypes of MDS: refractory anemia with ringed sideroblasts (RARS), chronic myelomonocytic leukemia (CMML) if white blood counts > 13x10^9/L or MDS/myeloproliferative diseases (MPD).
• Has MDS associated with a 5q chromosomal deletion unless patient received prior lenalidomide treatment.
• Has MDS presumed secondary to exposure to chemicals or treatment with radiotherapy or chemotherapy.
• Received any treatment with investigational agents, within 4 weeks prior to the first infusion of rATG.
• Has any of the following abnormalities:a.Serum Creatinine > 1.5 x upper limit of normal (ULN).b.Aspartate transaminase (AST) and alanine transaminase (ALT) > 2.5 x ULN.c. Serum total bilirubin > 1.5 x ULN except for unconjugated hyperbilirubinemia related to the patients's MDS
• Received any treatment with non-steroidal anti-inflammatory drugs (NSAID)within 14 days prior to the start of treatment.
• Is known to be human immunodeficiency virus (HIV) positive.
• Has any prior diagnosis of malignancy other than MDS, unless the patient has been disease-free for at least 5 years following the completion of curative intent therapy.
• Any serious medical condition (other than MDS) that would limit survival to < 2 years.
• Active acute or chronic infection, including cytomegaloviremia (CMV), or deep tissue infection.
• Any other serious medical condition, uncontrolled illness (including, but not limited to, symptomatic congestive heart failure, unstable angina pectoris, or cardiac arrhythmia), social condition, or psychiatric illness that will prevent the patient from signing the informed consent document (ICD), or will place the patient at unacceptable risk if he/she participates in the study, or that would limit compliance with study requirements.