Rabbit Anti-thymocyte Globulin in the Treatment of Patients With Low to Intermediate-1 Risk Myelodysplastic Syndrome

Inclusion Criteria: * Patient provided signed written informed consent. * Patient had pathologically confirmed low or intermediate-1 risk MDS at the time of MDS diagnosis and at the time of screening. * Patient had received no more than 1 prior treatment for MDS. * Patient exhibited at least 1 hematologic cytopenia (anemia, neutropenia, or thrombocytopenia) over a period of ≥1 week. * Patient had documentation of any prior transfusion requirements. * Patient had an Eastern Cooperative Oncology Group (ECOG) performance score of 0, 1, or 2. * Patient was ≥18 and ≤70 years of age at time of signing the informed consent document (ICD). * Patient was able to adhere to study visit schedule and all other protocol requirements. * Patient was 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) (fertile male and female patients). Exclusion Criteria: * Patient was pregnant or lactating. * Patient has had prior treatment with any ATG. * Patient has received any immunomodulatory or immunosuppressing agents (excluding steroids) \<12 weeks prior to the first infusion of rATG. * Patient has had a prior hematopoietic stem cell transplantation and/or other organ transplant. * Patient has had a prior allergic reaction to rabbit proteins or excipients. * Patient had 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 other MDS/myeloproliferative diseases (MPD). * Patient had MDS associated with a 5q chromosomal deletion unless the patient received prior lenalidomide treatment \<4 weeks prior to the first infusion of rATG. * Patient had MDS presumed secondary to exposure to chemicals or treatment with radiotherapy or chemotherapy. * Patient received any investigational agents within 4 weeks prior to the first infusion of rATG. * Patient has any of the following abnormalities: serum creatinine \>1.5 x upper limit of normal (ULN); aspartate transaminase (AST) and alanine transaminase (ALT) \>2.5 x ULN; or serum total bilirubin \>1.5 x ULN, except for unconjugated hyperbilirubinemia related to the patient's MDS. * Patient received any treatment with non-steroidal anti-inflammatory drugs (NSAIDs) within 14 days prior to the start of treatment. * Patient was known to be human immunodeficiency virus (HIV) positive. * Patient had any prior diagnosis of malignancy other than MDS, unless the patient had been disease-free for at least 5 years following the completion of curative intent therapy. * Patient had any serious medical condition (other than MDS) that would limit survival to \<2 years. * Patient had active acute or chronic infection, including cytomegaloviremia (CMV) infection or deep tissue infection. * Patient had 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 would prevent the patient from signing the informed consent document (ICD), or would place the patient at unacceptable risk if he/she participated in the study, or that would limit compliance with study requirements.