CD33 is variably expressed on leukemia blasts in almost all patients with acute myeloid leukemia (AML) and possibly leukemia stem cells in some. Efforts to target CD33 therapeutically have focused on ...gemtuzumab ozogamicin (GO; Mylotarg), an antibody-drug conjugate delivering a DNA-damaging calicheamicin derivative. GO is most effective in acute promyelocytic leukemia but induces remissions in other AML types and received accelerated approval in the US in 2000. However, because a large follow-up study showed no survival improvement and increased early deaths the drug manufacturer voluntarily withdrew the US New Drug Application in 2010. More recently, a meta-analysis of data from several trials reported better survival in adults with favorable- and intermediate-risk cytogenetics but not adverse-risk AML randomized to receive GO along with intensive induction chemotherapy. As a result, GO is being re-evaluated by regulatory agencies. Responses to GO are diverse and predictive biological response markers are needed. Besides cytogenetic risk, ATP-binding cassette transporter activity and possibly CD33 display on AML blasts may predict response, but established clinical assays and prospective validation are lacking. Single-nucleotide polymorphisms in CD33 may also be predictive, most notably rs12459419 where the minor T-allele leads to decreased display of full-length CD33 and preferential translation of a splice variant not recognized by GO. Data from retrospective analyses suggest only patients with the rs12459419 CC genotype may benefit from GO therapy but confirmation is needed. Most important may be markers for AML cell sensitivity to calicheamicin, which varies over 100 000-fold, but useful assays are unavailable. Novel CD33-targeted drugs may overcome some of GO's limitations but it is currently unknown whether such drugs will be more effective in patients benefitting from GO and/or improve outcomes in patients not benefitting from GO, and what the supportive care requirements will be to enable their safe use.
Although reduced-intensity conditioning (RIC) and non-myeloablative (NMA)-conditioning regimens have been used for over a decade, their relative efficacy vs myeloablative (MA) approaches to ...allogeneic hematopoietic cell transplantation in patients with AML and myelodysplasia (MDS) is unknown. We compared disease status, donor, graft and recipient characteristics with outcomes of 3731 MA with 1448 RIC/NMA procedures performed at 217 centers between 1997 and 2004. The 5-year univariate probabilities and multivariate relative risk outcomes of relapse, TRM, disease-free survival (DFS) and OS are reported. Adjusted OS at 5 years was 34, 33 and 26% for MA, RIC and NMA transplants, respectively. NMA conditioning resulted in inferior DFS and OS, but there was no difference in DFS and OS between RIC and MA regimens. Late TRM negates early decreases in toxicity with RIC and NMA regimens. Our data suggest that higher regimen intensity may contribute to optimal survival in patients with AML/MDS, suggesting roles for both regimen intensity and graft vs leukemia in these diseases. Prospective studies comparing regimens are needed to confirm this finding and determine the optimal approach to patients who are eligible for either MA or RIC/NMA conditioning.
There is considerable interest in developing techniques to detect and/or quantify remaining leukaemia cells termed measurable or, less precisely, minimal residual disease (MRD) in persons with acute ...myeloid leukaemia (AML) in complete remission defined by cytomorphological criteria. An important reason for AML MRD-testing is the possibility of estimating the likelihood (and timing) of leukaemia relapse. A perfect MRD-test would precisely quantify leukaemia cells biologically able and likely to cause leukaemia relapse within a defined interval. AML is genetically diverse and there is currently no uniform approach to detecting such cells. Several technologies focused on immune phenotype or cytogenetic and/or molecular abnormalities have been developed, each with advantages and disadvantages. Many studies report a positive MRD-test at diverse time points during AML therapy identifies persons with a higher risk of leukaemia relapse compared with those with a negative MRD-test even after adjusting for other prognostic and predictive variables. No MRD-test in AML has perfect sensitivity and specificity for relapse prediction at the cohort- or subject levels and there are substantial rates of false-positive and -negative tests. Despite these limitations, correlations between MRD-test results and relapse risk have generated interest in MRD-test result-directed therapy interventions. However, convincing proof that a specific intervention will reduce relapse risk in persons with a positive MRD-test is lacking and needs testing in randomized trials. Routine clinical use of MRD-testing requires further refinements and standardization/harmonization of assay platforms and results reporting. Such data are needed to determine whether results of MRD-testing can be used as a surrogate end point in AML therapy trials. This could make drug-testing more efficient and accelerate regulatory approvals. Although MRD-testing in AML has advanced substantially, much remains to be done.
We describe outcomes after allogeneic hematopoietic cell transplantation (HCT) for mycosis fungoides and Sezary syndrome (MF/SS). Outcomes of 129 subjects with MF/SS reported to the Center for the ...International Blood and Marrow Transplant from 2000-2009. Median time from diagnosis to transplant was 30 (4-206) months and most subjects were with multiply relapsed/ refractory disease. The majority (64%) received non-myeloablative conditioning (NST) or reduced intensity conditioning (RIC). NST/RIC recipients were older in age compared with myeloablative recipients (median age 51 vs 44 years, P=0.005) and transplanted in recent years. Non-relapse mortality (NRM) at 1 and 5 years was 19% (95% confidence interval (CI) 12-27%) and 22% (95% CI 15-31%), respectively. Risk of disease progression was 50% (95% CI 41-60%) at 1 year and 61% (95% CI 50-71%) at 5 years. PFS at 1 and 5 years was 31% (95% CI 22-40%) and 17% (95% CI 9-26%), respectively. OS at 1 and 5 years was 54% (95% CI 45-63%) and 32% (95% CI 22-44%), respectively. Allogeneic HCT in MF/SS results in 5-year survival in approximately one-third of patients and of those, half remain disease-free.
There are limited data on hematopoietic cell transplantation (HCT) in primary plasma cell leukemia (pPCL), an aggressive plasma cell disorder. We report outcomes of 147 patients with pPCL receiving ...autologous (n=97) or allogeneic (n=50) HCT within 18 months after diagnosis between 1995 and 2006. Median age was 56 years and 48 years for autologous HCT and allogeneic HCT, respectively. Progression-free survival (PFS) at 3 years was 34% (95% confidence interval (CI), 23-46%) in the autologous group and 20% (95% CI, 10-34%) in the allogeneic group. Cumulative incidence of relapse at 3 years was 61% (95% CI, 48-72%) in the autologous group and 38% (95% CI, 25-53%) in the allogeneic group. Overall survival (OS) at 3 years was 64% (95% CI, 52-75%) in the autologous group and 39% (95% CI, 26-54%) in the allogeneic group. Non-relapse mortality (NRM) at 3 years was 5% (95% CI, 1-11%) in the autologous group and 41% (95% CI, 28-56%) in the allogeneic group. The encouraging OS after autologous HCT, establishes the safety and feasibility of this consolidative treatment option after initial induction therapy for pPCL. Allogeneic HCT, although associated with a significantly lower relapse rate, carries a much higher risk of NRM and no OS benefit.
Allogeneic hematopoietic SCT is an effective treatment in accelerated (AP) or blast phase (BP) CML. Imatinib (IM) has transient but significant activity in advanced phases of CML, which may permit ...early allografting for responding patients. To identify prognostic factors in allograft recipients previously treated with IM, we analyzed 449 allogeneic hematopoietic SCTs performed from 1999 to 2004 in advanced-phase CML, using the data reported to the Center for International Blood and Marrow Transplant Research. CML patients in second chronic phase (CP2, n=184), AP (n=185) and BP (n=80) received HLA-identical sibling (27%), related (3%), or matched or mismatched unrelated donor (70%), peripheral blood (47%) or BM (53%) hematopoietic SCT after myeloablative (78%) or non-myeloablative (22%) conditioning. In all, 52% in CP2, 49% in AP and 46% in BP received IM before hematopoietic SCT. Disease-free survival was 35-40% for CP2, 26-27% for AP and 8-11% for BP. Cumulative incidence of acute and chronic GVHD and TRM were not affected by the stages of CML or pre-hematopoietic SCT IM exposure. Multivariate analyses showed that conventional prognostic indicators remain the strongest determinants of transplant outcomes. In conclusion, there are no new prognostic indicators of the outcomes of allogeneic hematopoietic SCT for advanced-phase CML in the IM era.
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