Nonmyeloablative Conditioning and Hematopoietic Cell Transplantation (HCT) from HLA-Matched Related or Unrelated Donors for Chemotherapy-Refractory Chronic Lymphocytic Leukemia (CLL).

Sixty-four patients (pts) with chemotherapy-refractory CLL who were ineligible for ablative allogeneic HCT due to age and/or comorbidities were given nonablative-HCT from related (n=44) or unrelated donors (n=20) between 1997-2003 (Table). Median pt age was 56 (range 44–69) years, interval from diagnosis to HCT was 4.4 (3–25) years, and number of prior regimens was 4 (range 1–12). Sixty-one pts were refractory to at least 1 regimen, 56 to fludarabine (FLU), 19 to alkylating agents, 14 to rituxumab and 4 to CAMPATH, and 2 had failed autologous HCT. Twenty-three pts (36%) had disease responsive to last chemotherapy [28% partial (PR) and 8% complete remission (CR)] while 34 were nonresponsive and 7 had untested relapse. Conditioning for HCT consisted of 2 Gy TBI alone (n=11) or combined with FLU (n=53), 90 mg/m². Postgrafting immunosuppression consisted of mycophenolate mofetil and cyclosporine. Pts received G-CSF mobilized peripheral blood mononuclear cells. After HCT, pts became neutropenic for a median of 11 days. Forty-four percent of pts had thrombocytopenia (<20,000 cells/ul). Three pts had graft rejection; 1 died with aplasia and 2 are alive with disease relapse. Incidences of grades II, III, and IV acute GVHD were 39%, 14%, and 2% respectively, and chronic GVHD was 50% at 2-years. With median follow up of 24 (range 2.8–62.8) months, the overall response rate was 67% (50% in CR). URD-pts had significantly higher CR rate than MRD-pts. All 11 responding patients tested had molecular eradication of their disease. Overall, 39 patients are alive; 25 in CR, 5 in PR, 2 with stable disease, and 7 with relapse/progression. Twenty-five pts died, 10 from progression, 10 from infections ± GVHD, 2 from cardiac causes, 1 from metastatic lung cancer, 1 from cerebral stroke and 1 from rejection and aplasia. Estimated 2-year rates of non-relapse mortality, disease free survival, and overall survival were 22%, 52%, and 60% respectively. In multivariate analysis, high pretransplant comorbidity scores predicted higher non-relapse mortality and worse survival while bulky lymphadenopathy predicted increased risk of progression. CLL appears susceptible to graft-versus-leukemia effects particularly after URD grafts and nonablative-HCT should be explored in phase II trials in pts with FLU-refractory CLL.

Table: Results