A Multi-center Randomized Phase II Study of the Impact of CD34+ Cell Dose on Absolute Lymphocyte Count Following High-Dose Therapy and Autologous Stem Cell Transplantation for Relapsed and Refractory Diffuse Large B-cell Lymphoma (DLBCL)

• Age ≥ 18 years old

• Diagnosed with relapsed or refractory de novo DLBCL or follicular lymphoma transformed to DLBCL to one previous line of anthracycline-containing chemotherapy

• KPS ≥ 70

• Complete or partial response by IWG Working Group or ICML Criteria to maximum of one salvage line of chemotherapy without pre-HDT/ASCT salvage radiotherapy.

• Eligible for high-dose therapy and autologous stem-cell rescue

‣ Serum creatinine ≤ 1.5 mg/dL, or if creatinine \>1.5 mg/dL, calculated creatinine clearance of ≥50 mL/min by 24 hour creatinine clearance or CKD-EPI.

⁃ Last cycle of most recent salvage therapy within 8 weeks of enrollment

• Total bilirubin \< 2.0 mg/dL

• o If Gilberts disease is suspected and total bilirubin \> 2.0 mg/dL, direct bilirubin must be \< 2.0 mg/dL

• Females of childbearing potential and males must agree to use an acceptable form of contraception per institutional practices.