Maraviroc on HIV-1 Infected Subjects Who Require Allogeneic Hematopoietic Cell Transplant

Inclusion Criteria (Step 1) * HIV-1 infection, documented by any licensed rapid HIV test or HIV enzyme or chemiluminescence immunoassay (E/CIA) test kit at any time prior to study entry and confirmed by a licensed Western blot or a second antibody test by a method other than the initial rapid HIV and/or E/CIA, or by HIV-1 antigen, plasma HIV-1 RNA VL. * Receipt of allo-HCT for any indication at least 100 days prior to study entry. * Receipt of maraviroc for at least 30 days starting at date of transplant. Longer receipt of maraviroc is acceptable. Documentation of HIV-1 tropism for CCR5 should be obtained if available, but it is not necessary that the participant have prior CCR5-tropic. * At least 18 years of age. * HIV-1 RNA that is \<50 copies/mL using a FDA-approved assay performed by any laboratory that has a CLIA certification or its equivalent within 45 days prior to study entry. * For females of reproductive potential (i.e., women who have not been post-menopausal for at least 24 consecutive months, who have had menses within the preceding 24 months, or women who have not undergone surgical sterilization, specifically hysterectomy and/or bilateral oophorectomy or bilateral salpingectomy), negative urine pregnancy test (with a sensitivity of 15-25 mIU/mL) within 48 hours prior to screening and entry. * Negative HBsAg result obtained within 6 months prior to study entry, or documentation of HBV immunity by positive HBV sAb at any time * The following laboratory values obtained within 45 days prior to enrollment: * CD4+ T cell count \>250 cells/ mm\^3 * Absolute neutrophil count (ANC) ≥1000 cells/mm\^3 * Hemoglobin ≥10.0 g/dL for men and ≥9.0 g/dL for women * Platelet count ≥ 50,000/mm3 * Ability and willingness of participant or legal representative to provide informed consent. Additional Inclusion Criteria for Step 2 of Study: * HIV-1 latent reservoir undetectable by co-culture and DNA * No confirmed detectable HIV-1 RNA \> 1000 cells/mm3 since discontinuation of maraviroc * Prior HIV-1 genotype results that confirm that there are active agents available in at least three classes of ART drugs (NRTI, NNRTI, PI or integrase). * Willing to stop ART * Willing to undergo high volume blood draw (125 cc) at Week 16 * Willing to restart ART if HIV-1 viremia returns * Provide informed consent for Step 2 Exclusion Criteria: * Ongoing AIDS-related opportunistic infection (including oral thrush). * Pregnant and/or breastfeeding.