Methylprednisolone, Horse Anti-Thymocyte Globulin, Cyclosporine, Filgrastim, and/or Pegfilgrastim or Pegfilgrastim Biosimilar in Treating Patients With Aplastic Anemia or Low or Intermediate-Risk Myelodysplastic Syndrome

Inclusion Criteria:

1. Patients with the diagnosis of MDS (Low, Int-1 by IPSS, or hypocellular) who areeither previously treated or untreated are eligible for this trial.

2. Patients with the diagnosis of aplastic anemia who are either previously treated oruntreated are eligible if they are not currently candidates for an allogeneic stemcell transplant.

3. Patients ages 18 years and older are eligible

4. Patients must have been off of cytotoxic, immunosuppressive (except steroids), ortargeted therapy for at least 2 weeks prior to entering this study, and haverecovered from the toxic effects of that therapy to grade 1 or less.

5. Adequate organ function as defined below:

• liver function (bilirubin < 2mg/dL, AST <3 x ULN)

• kidney function (creatinine < 2.5 x ULN ).

6. ECOG performance status of ≤ 2.

7. Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry andfor the duration of study participation. Should a woman become pregnant or suspectshe is pregnant while participating in this study, she should inform her treatingphysician immediately.

8. A negative urine pregnancy test is required within 1 week for all women ofchildbearing potential prior to enrolling on this trial.

9. Patient must have the ability to understand the requirements of the study and signedinformed consent. A signed informed consent by the patient or his legally authorizedrepresentative is required prior to their enrollment on the protocol.

10. Patients should have an indication for therapy for their disease such as transfusiondependence or morbidity associated with their cytopenia(s) such as bleeding, severefatigue, or frequent/multiple infections (eg. neutropenia).

Exclusion Criteria:

1. Pregnant women are excluded from this study. Because there is an unknown butpotential risk for adverse events in nursing infants secondary to treatment of themother with the study agents, breastfeeding should be discontinued if the mother istreated on this study.

2. Known HIV infection.

3. Uncontrolled intercurrent illness including, but not limited to, ongoing or activeinfection, symptomatic congestive heart failure, unstable angina pectoris, cardiacarrhythmia, or psychiatric illness/social situations that would limit compliancewith study requirements.

4. Patient with documented hypersensitivity to any of the component medications.