The role of autologous transplantation for acute myeloid leukemia in first and second remission

Conditioning regimens in acute myeloid leukemia

Current intensive consolidation chemotherapy for patients with acute myeloid leukemia (AML) produces median remission duration of 12-18 months, with less than 30% of patients surviving 5 years free of disease. Post-remission therapy is necessary to prevent relapse in most patients with AML; therefore, the aim of post-remission treatment is to eradicate the minimal residual disease. Nevertheless, the optimal form of treatment is still under debate. The choice among the possible approaches (intensive chemotherapy, autologous or allogeneic hematopoietic stem cell transplantation) relies on two main factors: the expected risk of relapse, as determined by biological features, and expected morbidity and mortality associated with a specific option. In this review, we focus on the different preparative regimens before autologous and allogeneic hematopoietic stem cell transplantation in patients with AML, stressing the importance of an adequate conditioning regimen as a mandatory element of a successful AML therapy, in both the allogeneic and the autologous transplant setting.

In the absence of clinically significant graft vs. host disease, myeloablative conditioning may allow an effective graft vs. leukaemia effect

In AML, prevention of GvHD leads to better tolerance of myeloablative therapy. 66 individuals with AML in CR underwent myeloablative conditioning and transplantation with allogeneic PBPC grafts. Median presentation age was 44.5 years. Karyotyping was intermediate in 48% and of unfavourable risk in 36%. For GvHD prophylaxis, PBPC harvests were incubated ex vivo with anti CD52 antibodies. TRM at day 100 and 1 year was 9% and 17%. At a median of 1018 days 65% are alive. Grade >1 GvHD was seen in 11%. GvHD and adverse karyotype were associated with treatment failure. In younger patients preservation of the dose intensity may improve cure rates.

Higher incidence of relapse in patients with acute myelocytic leukemia infused with higher doses of CD34+ cells from leukapheresis products autografted during the first remission

The stem cell source for autologous transplantation has shifted from bone marrow to peripheral blood (PB). We previously showed that relapse incidence in patients with acute myelocytic leukemia autografted in first remission (CR1) was greater with PB than bone marrow, and a poorer outcome was associated with a shorter CR1 to PB transplantation interval (≤ 80 days). Leukemic and normal progenitors are CD34(+) and can be concomitantly mobilized; we assessed whether an association exists between the infused CD34(+) cell dose and outcome. The infused CD34(+) cell doses were available for 772 patients autografted more than 80 days after CR1 and were categorized by percentiles. We selected the highest quintile (> 7.16 × 10(6)/kg) as the cutoff point. By multivariate analysis, relapse was more probable in patients who received the highest dose (hazard ratio = 1.48; 95% confidence interval, 1.12-1.95; P = .005), and leukemia-free survival was worse (hazard ratio = 0.72; 95% confidence interval, 0.55-0.93; P = .01). In conclusion, in patients autografted in first remission, relapse was higher and leukemia-free survival lower for those who received the highest CD34(+) PB doses.

Is there a role for autologous stem cell transplantation for patients with acute myelogenous leukemia? A retrospective analysis

For patients with acute myelogenous leukemia (AML) who are unable to secure an acceptable HLA donor, the role of autologous stem cell transplantation (auto-SCT) has remained controversial. Its effectiveness remains unclear as, when analyzed on intention-to-treat strategies, a significant number do not undergo the procedure, whereas others seem to fail therapy from pretransplant recurrences. To improve our counseling to our patients on these 2 therapeutic options, we compared the outcome of patients in first remission of AML who actually underwent autologous or allogeneic transplantation. The choice for the type of graft was based on availability of HLA identical siblings. Patients received myeloablative conditioning followed by allogeneic or autologous cytokine mobilized peripheral blood stem cell transplantation. For prophylaxis of graft-versus-host disease (GVHD), grafts were incubated ex vivo with anti-CD52 antibodies and patients were prescribed cyclosporin until day 90. Patients were stratified by clinical and laboratory factors as well as cytogenetic risk. The endpoints were treatment-related mortality (TRM), disease-free survival (DFS), and overall survival (OS). The median presentation age for both transplant groups was 35 (14-60) years. Of the 112 consecutive patients achieving remission, autologous or allogeneic grafts were transplanted to 43 and 32 patients, respectively. There was no significant difference in the presentation clinical features, laboratory parameters, marrow morphology, or proportion of low and intermediate cytogenetic risk for both transplant options. Treatment mortality as well as relapse rate was similar (14% and 15%; 39% and 27%, respectively). At a median of 1609 and 1819 posttransplant days, 56% and 63% in each group survived. In univariate analysis performance status, cytogenetic risk, morphologic features of dysplasia, blast count, and lactate dehydrogenase (LDH) were significant factors for survival. Although for the entire group there was no difference in survival between both modalities, all patients with unfavorable cytogenetics receiving an autologous graft died of disease recurrence (3-year survival 35% versus 0%; P = .05). We conclude that patients with AML who have low or intermediate cytogenetic risk undergoing myeloablative conditioning followed by autologous or allogeneic T cell-depleted stem cell transplantation appeared to have similar outcome. However, those with unfavorable karyotype are unlikely to be cured with autologous grafts and are candidates for experimental modalities.

Higher incidence of relapse with peripheral blood rather than marrow as a source of stem cells in adults with acute myelocytic leukemia autografted during the first remission

PURPOSE

The cell source for autologous stem cell transplantation has shifted from bone marrow (BM) to peripheral blood (PB). In acute myelocytic leukemia (AML), for patients who receive transplants during first complete remission (CR1), no prospective randomized study has compared relapse incidence (RI) to cell source.

PATIENTS AND METHODS

We analyzed 2,165 patients who received autografts (1,607 PB and 558 BM) from 1994 to 2006 and were reported to the European Cooperative Group for Blood and Marrow Transplantation with complete research data. Relative to the time of CR1, PB transplants were performed earlier than BM transplants. Because a poorer outcome was associated with a shorter interval from CR1 to transplantation, patients were divided into three groups: BM, early PB (< or = 80 days after CR1), and late PB (> 80 days after CR1) transplantation.

RESULTS

In a multivariate analysis adjusted for differences between groups and center, RI was higher with both early PB (56% +/- 3%; hazard ratio [HR], 1.45; 95% CI, 1.11 to 1.9; P = .006) and late PB transplantation (46% +/- 2%; HR, 1.3; 95% CI, 1.06 to 1.59; P = .01) as compared with BM transplantation (39% +/- 2%). This translated into a significantly worse leukemia-free survival (LFS) for early PB transplantation (36% +/- 3%; HR, 0.75; 95% CI, 0.58 to 0.96; P = .02) and a trend for a poorer LFS for late PB (46% +/- 2%; HR, 0.84; 95% CI, 0.7 to 1.01; P = .06) as compared with BM (52% +/- 2%).

CONCLUSION

For patients with AML in CR1, risk of relapse is greater with PB transplantation rather than BM, independent of the interval from CR1 to transplantation.

Autologous stem cell transplantation for elderly patients with acute myeloid leukaemia conditioned with continuous infusion idarubicin and busulphan

Different studies have suggested the potential utility of autologous stem cell transplantation (ASCT) in acute myeloid leukaemia (AML) of the elderly with encouraging results in selected patients. However, while the introduction of peripheral blood stem cells (PBSC) has consistently reduced morbidity and mortality of the procedure, relapse still represents the major cause of ASCT failure. One possibility to ameliorate therapeutic results could rely on the adoption of conditioning regimens specifically designed for AML. We report therapeutic results from a series of 40 AML patients older than 60 years (median age 67 years) autografted in first complete remission (CR), after conditioning with continuous infusion (c.i.) high dose idarubicin and busulphan. Fourty patients (median age: 67 years) received 2 days c.i. idarubicin at 20 mg/m(2)/day, followed by 3 days oral or intravenous busulphan (4 mg/kg/day) as conditioning. No case of transplant-related mortality occurred. Cardiac toxicity was absent, while 31 patients (77%) had grade 3-4 mucositis. After a median follow-up of 25 months, median disease free and overall survival (OS) for the whole patient population were 13 and 22 months, respectively. Three patients died while in CR from causes unrelated to AML. Better results were achieved in patients with intermediate karyotype as opposed to those with adverse cytogenetics. Our data confirm the feasibility of a conditioning regimen based on high-dose idarubicin plus busulphan in older selected AML patients and suggest clinical improvement in patients with normal cytogenetics.