B-Cell Recovery and IVIG Independence in Pediatric Allogeneic BMT Recipients at the Medical University of South Carolina

Background: Pediatric Hematopoietic Stem Cell Transplant (HSCT) Programs vary in their use of IVIG. Programs may infuse IVIG for IgG levels below a certain threshold, or not at all. There are published data that both support and recommend against this practice. We reviewed our programs data on B-Cell Recovery and time to IVIG independence. Methods: A retrospective chart review was conducted for pediatric allogeneic HSCT recipients at MUSC from 9/2010 through 9/2016. Patients were excluded from analysis if they did not survive > 100 days post HSCT. We reviewed the diagnosis, conditioning regimen, GVHD prophylaxis, donor source, survival, and date of last IVIG infusion, and time to absolute CD 19 count recovery. For patients who did not receive IVIG, we verified their IgG levels did not drop below 400 mg/dl. We defined B-Cell recovery as the time to normal absolute CD19 count and reviewed data for the first year post HSCT. Results: Sixty-six patients received allogeneic HSCT at MUSC between 9/2010, through 9/2016. For these recipients 44/66 required IVIG at least once for an IgG level below 400 mg/dl. The median day to IVIG independence was 95 days (Range: 0 to 1929 days) post HSCT. Two patients (1 received rituximab, and one is receiving treatment for chronic GVHD) required IVIG for >1000 days. For the 22 patients that did not require IVIG we reviewed their BMT characteristics. The source of donor cells was: matched sibling donor marrow (N = 8), umbilical cord blood (N = 7), Peripheral blood stem cells (N = 1) and matched unrelated donor marrow (N = 6). Eight had a non-malignant and 14 had a malignant diagnosis. Eighteen received myeloablative conditioning. B-Cell recovery was evaluated in 51 recipients. Forty of the 51 patients had a CD19 count in the normal range (>100/CUMM) at a median of 179 days (Range: 30-365days) post HSCT. Fifteen patients did not have B-cell recovery data. This is due to prolonged BMT stays, or death after day 100, but before day 180. Eleven patients had delayed CD19 recovery, and 7 patients continued to have an abnormally low absolute CD 19 count at the subsequent time point. For patients with delayed CD19 recovery and a non-malignant diagnosis (N = 4) are alive and well. Patients with malignant diagnosis and delayed CD19 recovery (N = 7) had 5 deaths due to relapse, and 2 patients who required GvHD treatment. Conclusions: The median time to IVIG independence was approximately 3 months post HSCT with an extremely large range- suggesting that BMT course may have a greater affect on the need for IVIG than conditioning regimen, diagnosis, or donor source. One third of the patients did not receive any IVIG, and the at group was heterogeneous for conditioning regimen, diagnosis, and donor source. Most allogeneic recipients had a normal B-Cell count at the first time point tested suggesting that our standard time points may not capture data on early B-Cell recovery.