1. Cyclophosphamide 50mg/kg/day IV on Days -5,-4
2. Total Body Irradiation (TBI) 200cGy twice a day on Days -3, -2, -1
3. Infusion of non-T-cell depleted bone marrow on Day 0

Although a schedule is proposed above, the regimen can be given according to institutional standards as long as the prescribed doses are the same as in the recommended regimen above.

• Cy 14.5 mg/kg/day is administered as a 1-2 hour IV infusion on Days -6 and -5 after hydration.
• Use of Mesna and dosing will be done according to institutional standards. A recommended approach is as follows: Mesna IV dose of ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy.
• Hydration prior to Cy may be given according to institutional guideline.
• Cy and mesna are dosed according to adjusted IBW (Appendix K), unless the subject weighs less than IBW, in which case these drugs will be dosed according to actual weight.

• 200 cGy TBI is administered in a single fraction on Day -1.
• Radiation sources, dose rates, and shielding follow institutional practice.

• On Day 0, the harvested bone marrow is infused.
• Donor bone marrow will be harvested with a target yield of 4 x 108 nucleated cells/kg recipient weight.
• The lowest acceptable nucleated cells yield is 1.5 x 108 cells/kg recipient weight.

• Busulfan ≥ 9mg/kg total dose (IV or PO) on Days -6, -5, -4, -3 (PK monitoring required to achieve a daily area under the curve (AUC) target of 4800-5300 μM*min (Perkins et al., 2012))
• Busulfan dosing is based on adjusted IBW (Appendix K)

• Cy 50mg/kg/day is administered as a 1-2 hour IV infusion on Days -2 and -1 after hydration.
• Use of Mesna and dosing will be done according to institutional standards. A recommended approach is as follows: Mesna IV dose of ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy.
• Hydration prior to Cy may be given according to institutional guideline.
• Cy and mesna are dosed according to adjusted IBW (Appendix K), unless the subject weighs less than IBW, in which case these drugs will be dosed according to actual weight.

• Cy 50mg/kg/day is administered as a 1-2 hour IV infusion on Days -5 and -4 after hydration.
• Use of Mesna and dosing will be done according to institutional standards. A recommended approach is as follows: Mesna IV dose of ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy.
• Hydration prior to Cy may be given according to institutional guideline.
• Cy and mesna are dosed according to adjusted IBW (Appendix K), unless the subject weighs less than IBW, in which case these drugs will be dosed according to actual weight.

• 200cGy TBI is administered in twice daily on Days -3, -2, and -1.
• Radiation sources, dose rates, and shielding follow institutional practice.

• Cy 50mg/kg IV, over 1-2 hours (depending on volume), is given on Day+3 (ideally between 60 and 72 hours after bone marrow infusion) and on Day+4 (approximately 24 hours after Day+3 Cy).
• Hydration with Cy, management of volume status, and monitoring for hemorrhagic cystitis will follow institutional standards.
• Mesna is required. Mesna IV dose must be ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy.
• Cy is dosed according to IBW, unless the subject weighs less than IBW, in which case these drugs will be dosed according to actual body weight.

• Sirolimus dosing is based on adjusted IBW (Appendix K).
• Sirolimus prophylaxis is discontinued after the last dose on Day+180, or may be continued if there is GVHD.

For subjects ≥ 18 years old:

• A one-time sirolimus loading dose, 6 mg PO, is given on Day+5, at least 24 hours after Cy completion.
• Sirolimus is then continued at a maintenance dose (starting dose 2 mg PO QD), with dose adjustments to maintain a trough of 5 - 15 ng/mL as measured by high performance liquid chromatography (HPLC) or immunoassay.

For subjects < 18 years old:

• A one-time sirolimus loading dose, 3 mg/m2 PO with the dose not to exceed 6 mg, is given on Day+5, at least 24 hours after Cy completion.
• Sirolimus is then continued at a maintenance dose (starting dose 1 mg/m2 PO QD, maximum 2 mg PO QD), with dose adjustments to maintain a trough of 5 - 15 ng/mL as measured by HPLC or immunoassay.

MMF begins on Day+5, at least 24 hours after completion of PTCy. MMF dose is 15 mg/kg PO TID (adjusted IBW (Appendix K)) with total daily dose not to exceed 3 grams (i.e. maximum 1 g PO TID).

An equivalent IV dose (1:1 conversion) may instead be given. MMF prophylaxis is discontinued after the last dose on Day+35, or may be continued if there is GVHD.

Granulocyte-colony stimulating factor (G-CSF): filgrastim or a biosimilar begins on Day+5 at a dose of 5 mcg/kg/day (actual body weight) IV or subcutaneously (SC) (rounding to the nearest vial dose is allowed), until the absolute neutrophil count (ANC) is ≥ 1,000/mm3 over the course of 3 consecutive days.

Additional G-CSF may be administered as warranted.

Use of Mesna and dosing will be done according to institutional standards. A recommended approach is as follows: Mesna IV dose of ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy.

Mesna is dosed according to adjusted IBW (Appendix K), unless the subject weighs less than IBW, in which case Mesna will be dosed according to actual weight.

Use of Mesna and dosing will be done according to institutional standards. A recommended approach is as follows: Mesna IV dose of ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy.

Mesna is dosed according to adjusted IBW (Appendix K), unless the subject weighs less than IBW, in which case Mesna will be dosed according to actual weight.

Use of Mesna and dosing will be done according to institutional standards. A recommended approach is as follows: Mesna IV dose of ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy.

Mesna is dosed according to adjusted IBW (Appendix K), unless the subject weighs less than IBW, in which case Mesna will be dosed according to actual weight.

Mesna is required. Mesna IV dose must be ≥ 80% of the total daily dose of Cy and given in divided doses 30 minutes before and at 3, 6, and 8-9 hours after completion of Cy on Day+3 and Day+4.

Mesna is dosed according to IBW, unless the subject weighs less than IBW, in which case Mesna will be dosed according to actual body weight.

Achieving a donor derived ANC ≥ 500/mm3 for 3 consecutive laboratory values on different days. A cumulative incidence will be computed along with a 90% CI.

Achieving a platelet count ≥ 20,000/μL for 3 consecutive laboratory values on different days (with no platelet transfusions in the preceding seven days). A cumulative incidence will be computed along with a 90% CI.

Any skin, gastrointestinal or liver abnormalities fulfilling the BMT CTN Manual of Operations (2013) criteria of grades II-IV acute GVHD. A cumulative incidence will be computed along with a 90% CI.

Any skin, gastrointestinal or liver abnormalities fulfilling the BMT CTN Manual of Operations (2013) criteria of grades III-IV acute GVHD. A cumulative incidence will be computed along with a 90% CI.

Any skin, gastrointestinal or liver abnormalities fulfilling the BMT CTN Manual of Operations (2013) criteria of grades II-IV acute GVHD. A cumulative incidence will be computed along with a 90% CI.

Any skin, gastrointestinal or liver abnormalities fulfilling the BMT CTN Manual of Operations (2013) criteria of grades III-IV acute GVHD. A cumulative incidence will be computed along with a 90% CI.

Per National Institutes of Health (NIH) Consensus Criteria and includes organ involvement and severity, and overall global composite score (mild/moderate/severe). A cumulative incidence will be computed along with a 90% CI. Death from any cause. The time to this event is the time from HCT to death, loss to follow-up, or end of study (whichever comes first).

The overall survival probability and 90% CI will be calculated by the Kaplan Meier product limit estimator.

Grade 2: Clinically active CMV infection (e.g. symptoms, cytopenias) or CMV Viremia not decreasing by at least 2/3 of the baseline value after 2 weeks of therapy; Grade 3: CMV end-organ involvement (pneumonitis, enteritis, retinitis). A cumulative incidence will be computed along with a 90% CI. Death from any cause. The time to this event is the time from HCT to death, loss to follow-up, or end of study (whichever comes first).

The overall survival probability and 90% CI will be calculated by the Kaplan Meier product limit estimator.

CMV end-organ involvement (pneumonitis, enteritis, retinitis) ). A cumulative incidence will be computed along with a 90% CI. Death from any cause. The time to this event is the time from HCT to death, loss to follow-up, or end of study (whichever comes first). The overall survival probability and 90% CI will be calculated by the Kaplan Meier product limit estimator.

Grade 2: EBV reactivation requiring institution of therapy with rituximab; Grade 3: EBV post-transplant lymphoproliferative disorder). A cumulative incidence will be computed along with a 90% CI. Death from any cause. The time to this event is the time from HCT to death, loss to follow-up, or end of study (whichever comes first). The overall survival probability and 90% CI will be calculated by the Kaplan Meier product limit estimator.

BK viremia or viruria with clinical consequence requiring prolonged therapy and/or surgical intervention). A cumulative incidence will be computed along with a 90% CI.

Grade 2: Adenoviral URI, viremia, or symptomatic viruria requiring treatment; Grade 3: ADV with end-organ involvement (except conjunctivitis and upper respiratory tract) ). A cumulative incidence will be computed along with a 90% CI. Death from any cause. The time to this event is the time from HCT to death, loss to follow-up, or end of study (whichever comes first). The overall survival probability and 90% CI will be calculated by the Kaplan Meier product limit estimator.

Clinically active HHV-6 infection (e.g. symptoms, cytopenias) or HHV-6 viremia without viral load decline 0.5 log after 2 weeks of therapy). A cumulative incidence will be computed along with a 90% CI.

Defined by either morphological, cytogenetic/molecular or radiological evidence of disease consistent with pre-HCT features. A cumulative incidence will be computed along with a 90% CI. Death from any cause. The time to this event is the time from HCT to death, loss to follow-up, or end of study (whichever comes first). The overall survival probability and 90% CI will be calculated by the Kaplan Meier product limit estimator.

TMA is defined as (Ho et al., 2005):

1. RBC fragmentation and >2 schistocytes per high-power field on peripheral smear
2. Concurrent increased serum LDH above institutional baseline
3. Concurrent renal and/or neurologic dysfunction without other explanation
4. Negative direct and indirect Coombs test results A cumulative incidence will be computed along with a 90% CI.

VOD/SOS is defined as: In the first 20 days after HCT, the presence of ≥2 of the following: 1. Bilirubin >2 mg/Dl, 2. Hepatomegaly or pain in right upper quadrant, 3. Weight gain (>2% basal weight).

A cumulative incidence will be computed along with a 90% CI.

Lack of donor-derived neutrophil engraftment. The frequency of subjects experiencing primary graft failure by 56 days will be described.

Peripheral blood chimerism (% of donor chimerism) in whole blood (unsorted). The degree of donor chimerism will be summarized using descriptive statistics.

The frequency of subjects with Peripheral blood (unsorted) chimerism>95% at 56 days will be described.

The proportion of subjects proceeding to HCT after informed consent.

Time from search to donor identification Time from preliminary search to formal donor activation.

Number of matched donor and recipient HLA allele pairs. A matched donor would have 8/8 HLA allele pairs matching; mismatched donors listed below have one to four mismatched HLA allele pairs at HLA-A, -B, -C, or -DRB1.

Donor age

Donor age, categorical

Donor weight

Donor sex

Donor-recipient sex match

Donor-recipient Cytomegalovirus (CMV) serostatus match

Donor-recipient ABO group match

The proportion of subjects developing donor clonal hematopoiesis

If CCR5delta32 homozygous donors are successfully found and used for one or more HIV-positive subjects, a descriptive analysis of baseline characteristics and outcomes for those HIV-positive subjects will be conducted, including the viral load detected over time obtained from collected samples.