Abstract
NM-HCT from related donors who share at least one HLA haplotype with the recipient is a treatment option for patients with hematologic malignancies who do not have suitable HLA-matched related or unrelated donors. We have shown that addition of cyclophosphamide pre-transplant (29 mg/kg) and post-transplant (50 mg/kg on day+3 or days+3 and +4) to a standard nonmyeloablative conditioning regimen of fludarabine and TBI combined with tacrolimus and MMF prophylaxis of GvHD is an effective means of achieving complete engraftment of donor T-cells and granulocytes with low non-relapse mortality and an incidence and severity of acute and chronic GvHD which does not differ from studies of NM-HCT using HLA-matched donors. In a study of 89 patients (FHCRC,N=30; JH,N=59) with advanced myeloid and lymphoid malignancies, patients with relapsed HL had significantly better survival than patients with other diagnoses. Fifteen patients with HL were studied (median follow-up of 17 mo). Patients were heavily pre-treated with a median number of prior cytotoxic therapy regimens of 5 (range: 3–10); 14 patients had failed prior autologous HCT with a median time of 18 mo from auto-HCT to NM-HCT. Donors for 9 patients were HLA-mismatched at ≥4/10 loci. All evaluable patients were complete donor CD3 and CD33 chimeras by day +28 (one patient died on day +28 and was not evaluable). Clinically significant acute GvHD occurred in 9/14 (64%) patients and Grades III/IV GvHD in 3/14 (21%) patients. Extensive chronic GvHD occurred in 5/14 (36%) patients. Two patients (13%) died of non-relapse causes at days +236 and +633 secondary to chronic GvHD. Median failure-free survival (FFS) was 21 mo compared to 6 mo for patients with other lymphoid malignancies (N=23) or myeloid malignancies [(N=51), see Figure]. The hazard of mortality was less among patients with HL compared to those with other lymphoid malignancies [hazard ratio (HR)=0.36 (p=0.05)] yet patients with myeloid malignancies had a similar hazard of mortality compared to those with lymphoid malignancies other than HL [HR=0.88 (p=0.66)]. Difference in FFS between HL and other lymphoid malignancies was not statistically significant [HR=0.54 (p=0.16)], nor was the difference between myeloid and other lymphoid malignancies [HR=1.26 (p=0.44)]. More patients will need to be studied to better demonstrate a graft-versus-lymphoma effect of haploidentical transplantation in relapsed HL. NM-HCT from haploidentical donors may be a good option for such patients who have a limited window of opportunity to proceed to transplant if responsive to salvage chemotherapy.
Disclosures: Tacrolimus is approved for use in allogeneic liver and kidney transplantation and rheumatoid arthritis. Use of tacrolimus as prophylaxis of GvHD in hematopoietic cell transplantation is an off-label use.
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