Fludarabine-Melphalan Conditioning for AML and MDS: Alemtuzumab Reduces Acute and Chronic GVHD without Affecting Long-Term Outcomes Academic research paper on "Clinical medicine"

ASBMI

American Society for Blood and Marrow Transplantation

Fludarabine-Melphalan Conditioning for AML and MDS: Alemtuzumab Reduces Acute and Chronic GVHD without Affecting Long-Term Outcomes

1 2 3 3

Koen Van Besien, Rangesh Kunavakkam, Gaby Rondon, Marcos De Lima, Andrew Artz,1 Betul Oran,3 Sergio Giralt3

The purpose of this study was to determine the effect of alemtuzumab on treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DSF) in patients with acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS) undergoing reduced intensity conditioning (RIC). We compared the outcome of 95 patients treated at the University of Chicago with fludarabine melphalan (Flu 1 Mel) 1 alemtuzumab conditioning and 59 patients treated at the M.D. Anderson Cancer Center with Flu 1 Mel conditioning. Both groups had similar patient and donor characteristics. There were no significant differences in TRM, relapse, survival, and DFS between the 2 groups. The incidence of acute graft-versus-host disease (aGVHD) grade II-IV (relative risk [RR] 5.5, P < .01) and chronic GVHD (cGVHD) (RR 6.6, P <.01) were significantly lower in patients receiving alemtuzumab. The addition of alemtuzumab to an RIC regimen dramatically reduces the incidence of aGVHD and cGVHD in patients with AML and MDS undergoing allogeneic transplantation. TRM, relapse risk, OS and DFS are not affected. Biol Blood Marrow Transplant 15: 610-617 (2009) © 2009 American Society for Blood and Marrow Transplantation

KEY WORDS: Allogeneic transplant, AML, MDS, T cell depletion, Alemtuzumab

INTRODUCTION

Allogeneic hematopoietic stem cell transplantation (HSCT) offers the potential for prolonged disease-free survival (DFS) for patients with advanced myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML) [1-3]. However, such patients are often older, have chemotherapy-resistant disease, have decreased performance status, suffer from comorbidities, and lack related donors. With conventional total body irradiation (TBI) or busulfan (Bu)-based conditioning regimens followed by infusion of unmodified allografts, long-term survival rates range between 20% and 50%. Modification of conditioning regimens and graft-versus-host disease (GVHD) prophylaxis have

From the 'Section of Hematology/Oncology; 2The Department of Health Studies, University of Chicago, Chicago, Illinois; and Department of Blood and Marrow Transplantation, M.D. Anderson Cancer Center, Houston, Texas. Financial disclosure: See Acknowledgments on page 616. Correspondence and reprint requests to: Koen Van Besien, MD, Section of Hematology/Oncology, University of Chicago, 5841 South Maryland Avenue, Room 1 209, Chicago, IL 60637 (email: Kvbesien@uchicago.edu). Received October 19, 2008; accepted January 27, 2009 © 2009 American Society for Blood and Marrow Transplantation 1083-8791/09/155-0001$36.00/0 doi:10.1016/j.bbmt.2009.01.021

been investigated to improve outcomes in these high-risk populations.

The M.D. Anderson group pioneered the use of fludarabine melphalan (Flu + Mel) conditioning, which has since gained wide usage [4-7]. The use of high-dose Mel for conditioning in allogeneic transplantation is based on its convenience, its broad antitumor activity in hematologic malignancies, and its immuno-suppressive effects, initially described in animal models, but subsequently confirmed by empirical clinical observations [8,9]. Flu was added to this conditioning regimen because of its potent immunosuppressive effects and its potential synergism with alkylators [10].

The Flu + Mel conditioning regimen results in long-term survival of patients with advanced hemato-logic malignancies that is similar to that after TBI-based conditioning [4-7]. It is more efficacious than regimens that are further reduced in intensity (RIC) [4], and less toxic than combinations of Mel with 2CDA [11]. The most limiting side effect of this conditioning regimen is the high incidence of acute GVHD (aGVHD) and particularly chronic GVHD (cGVHD). In a recent M.D. Anderson series, the cumulative incidence of cGVHD was 49%, and cGVHD was the primary cause of death in 25% of patients [12]. Infections, often related to GVHD or its treatment, accounted for another 10 deaths. Fatal regimen-related complications also occur in 10% to 15% of patients receiving this conditioning

regimen. In vivo T cell depletion with alemtuzumab has been utilized in combination with Flu and Mel to reduce the incidence of severe aGVHD and cGVHD [13-17]. Posttransplant methotrexate (MTX), a cause of mucositis and liver toxicity is usually omitted in those regimens. Although the reduction in GVHD with alemtuzumab-containing conditioning regimens is well documented, there are concerns over increases in rates of disease recurrence and over increased risks of opportunistic infections, particularly cytomegalovirus (CMV), because of excessive immunocompromise [18,19]. To evaluate the impact of alemtuzumab on complications and outcome of allogeneic transplantation for AML and MDS, we compared the outcomes of 59 patients prospectively treated at the M.D. Anderson Cancer Center (MDACC) with that of 95 patients treated on a prospective study at the University of Chicago (UC).

PATIENTS AND METHODS

All patients were treated on institutional protocols approved by the local institutional review board. All patients and donors provided written informed consent. Patients at the UC were treated on a prospective institutional protocol for patients with hematologic malignancies. All patients with AML and MDS accrued to this protocol between February 2002 and October 2007 are included in this analysis. Fifty-seven of these patients have been reported previously [20].

Patients from MDACC were those with AML or high-risk MDS treated with the combination of Flu + Mel and allogeneic HSCT using bone marrow (BM) or peripheral blood progenitor cells (PBPCs). These patients have been reported previously [12]. One transplant occurred in 1997 and 1 in 1998. The remainder occurred between February 1999 and December 2003.

For categorization of patients, the American Society for Blood and Marrow Transplantation (ASBMT)/ Center for International Blood and Marrow Transplant Research (CIBMTR) criteria of high-, intermediate-, and low-risk disease were used. Low-risk AML patients are those in first complete remission (CR1). Intermediate risk are those in second or third remission, and high risk are those with active disease at the time of conditioning. For MDS patients, refractory anemia (RA) and refractory anemia with ring sidero-blasts (RARS) are considered low risk. All others are considered high-risk disease.

Donor Typing and Stem Cell Source

At the UC, acceptable donors were related or unrelated donors with no more than a 1-antigen mismatch after considering HLA-A, -B, -C, and -DR. Patients and donors for unrelated donor transplantation were typed for the HLA -A, -B, -C, and -DR loci by mo-

lecular sequencing techniques. At MDACC, acceptable donors were related or unrelated, serologically matched for HLA-A and -B, and matched for HLA-DRB1 by high-resolution molecular methods. At the UC, gran-ulocyte-colony stimulating factor (G-CSF) mobilized peripheral blood stem cell (PBSC) collections were preferred for both related and unrelated donors. At MDACC, PBSC collections were preferred for related, and BM harvest for unrelated donors.

Preparative Regimen and GVHD Prophylaxis

Patients at the UC received Flu 30 mg/m2/day intravenously (i.v.), alemtuzumab 20 mg/day i.v. for 5 consecutive days (days -7, -6, -5, -4, and -3), and Mel 140 mg/m2/day on day -2 . Acetaminophen, di-phenhydramine, and methylprednisolone or hydrocortisone were given to prevent alemtuzumab toxicity. GVHD prophylaxis consisted of tacrolimus adjusted to maintain blood levels of 5 to 15 ng/dL during the first 100 days and then tapered as indicated depending on donor type, and presence or absence of GVHD.

At MDACC the conditioning regimen consisted of Flu 25 to 30 mg/m2 for 4 to 5 days (transplant days —6 or —5 to —2) with Mel 100 mg/m2 for patients transplanted in CR1 (n = 13; 22%) or Mel 140 mg/m2 for those with more advanced disease (n = 46; 78%). Fifty-three additional patients from MDACC who received Mel 180 mg/m2 were not included because the higher doses of Mel were associated with increased treatment-related mortality (TRM). Mel was given on day — 2. Gemtuzumab ozogamicin 2 or 4 mg/m2 was added in 15 cases (day -12) [21]. Antithymocyte globulin (ATG) was given to 20 patients receiving an unrelated donor. GVHD prophylaxis consisted of tacrolimus and MTX 5 mg/m2 i.v. on days 1, 3, 6, and 11 after transplantation in all but 1 patient who received cyclosporine (CsA). Tacrolimus doses were adjusted to maintain blood levels of 5 to 15 ng/dL during the first 100 days and then tapered as indicated depending on donor type, presence, or absence of GVHD.

Infection Prophylaxis and Supportive Care

At the UC, patients who were CMV-positive or had a CMV-seropositive donor were given ganciclovir 5 mg/kg from day -8 until day -3. They then were given acyclovir 10 mg/kg every 8 hours i.v. until discharge. On discharge the vast majority were given valacyclovir 2000 mg four times a day until day 210 [22]. CMV-negative donor/recipient pairs received routine acyclovir prophylaxis. All patients were screened weekly for CMV viremia until day 120 and treated with ganciclovir or valganciclovir on detection of CMV viremia.

At MDACC, lower doses of acyclovir or valacyclo-vir were administered. Patients were screened biweekly

for CMV antigenemia with preemptive use of ganciclovir in the event of a positive assay.

Other aspects of supportive care were very similar between the 2 institutions and have been previously reported.

Posttransplantation Evaluation

Disease relapse was defined as disease progression from the best response. Death without disease progression was considered transplantation related. aGVHD and cGVHD were scored and treated according to standard criteria [23]. New definitions for aGVHD and cGVHD were not yet used in these studies [24]. At both institutions donor lymphocyte infusions (DLIs) were only used in case of overt disease persistence or relapse, and never for mixed or declinining chimerism. Patients requiring DLIs were considered treatment failures.

Statistical Methods

Progression-free survival (PFS) (time to relapse or death as a result of any cause), overall survival (OS), and cumulative probability of aGVHD and extensive cGVHD were calculated using the Kaplan-Meier product-limit estimate and expressed as probabilities with a 95% confidence interval (CI) [25,26]. For GVHD, patients who died without GVHD were censored at the time of death, and cumulative probability at time t was calculated as 1 - KM(t), where KM(t) is the KaplanMeier estimate of remaining event-free at time t. Cumulative incidence of disease progression with death before progression as the competing risk [27], and cumulative incidence of TRM with relapse of the original disease as the competing risk were also calculated. (See Chappell [28] or Klein et al [29] for a discussion of issues related to the use of 1 - KM vs cumulative incidence.)

Univariate comparisons and multivariate analyses used Cox proportional hazards regressions. Parameters calculated in the univariate and multivariate analyses included alemtuzumab use versus not (or its surrogate, the treating institution); administration of rabbit ATG versus not, disease status (low or intermediate risk versus high risk as defined by ASBMT/CIBMTR criteria), age, comorbidity scores (using the Seattle hema-topoietic cell transplantation-specific comorbidity [HCT-CI] index) [30], donor type (HLA-identical related donor versus antigen-mismatched related or unrelated donor), and dose of Mel (100 versus 140 mg/m2). For the multivariate Cox models, independent variables with P > 0.1 were excluded sequentially from the models. Alemtuzumab use versus not was retained in all steps of model-building because it was the main effect of interest. The relative risks and the associated P values of the remaining variables are reported. M.D. Anderson data were updated until November 2007; UC data until June 2008.

RESULTS

Patient and Treatment Characteristics

Patient, disease, and treatment characteristics are summarized in Table 1. The median age of patients transplanted at both institutions was identical, and there were no significant differences in disease type, CIBMTR risk score, cytogenetic risk group as defined in CALGB studies [31], proportion of patients with increased blasts at conditioning, or proportion of patients who had undergone a previous transplant. Those at MDACC had a somewhat higher average comorbidity score. Practically all patients at the UC received donor PBSC; half of those at MDACC received BM.

Univariate and Multivariate Analysis of Outcomes

The cumulative incidence of TRM, cumulative incidence of relapse, PFS, and OS are shown in Table 2. There are no significant differences in TRM, relapse rate, DFS, and OS between the 2 groups. With a median follow-up for survivors of 60 months atMDACC (range: 25-86 months) and of 37 months at the UC (range: 3-77 months), 2-year survival is 41% (95% CI, 31%-53%) for UC patients and 46% (95% CI, 35% to 53%) for the MDACC patients. The survival curves are nearly identical, and so are the PFS curves (Figures 1 and 2)

The cumulative incidence of grade III-IV aGVHD and of cGVHD are shown in Figures 3 and 4. Estimated rates are listed in Table 2. The cumulative risk of aGVHD and particularly of cGVHD was

Table 1. Patient Characteristics

University of MD Anderson

Chicago Cancer Center P-Value

N 95 59

Median age (range) 54 (11-77) 55 (22-74) .4

AML/MDS/t-AML 70/13/12 39/9/11 .5

ASBMT Low/intermediate/high 33/13/49 16/6/37 .3

Prior transplant auto/allo 13/2 8/0 .7

Cytogenetic risk group 5/57/31 j 2/35/22 .9

low/int/high

BM blast <5%/$ 5 48/47 34/25 .2

HCT-CI <3/>3 51/34 22/31* .05

Matched related/other 48/47 25/34 .3

BM/PB 3/92 26/33 <.01

Conditioning <.01

Alemtuzumab 95 0 <.01

Melphalan 100/140 0/95 13/46

ATG 0 20 <.01

GVHD Prophylaxis <.01

Tacrolimus 95 0

Tacrolimus/CsA + Methotrexate 0 59

AML indicates acute myelogenous leukemia; MDS, myelodysplastic syndromes; CsA, cyclosporine; GVHD, graft-versus-host disease; ATG, antithymocyte globulin; BM, bone marrow; PB, peripheral blood; ASBMT, American Society for Blood and Marrow Transplantation. *Data missing in 6 patients. jData missing in 2 patients.

Table 2. Outcome Probabilities

U Chicago MDACC

Outcome Probability (95% CI) Probability (95% CI) P-Values

Treatment-related mortality* .25

Day 100 11.5% (6.1-18.9) 16.9 (8.6-27.6)

1 year 24.6% (16.3-33.7) 28.8(17.8-40.7)

Relapse* .24

1 year 23.7% (15.6-32.9) 20.3% (11.1-31.5)

Progression free survivalf .95

2 years 33% (23.5-42.7) 35.6% (23.7-47.7)

Overall survivalf .92

2 years 40.5% (30.2-50.6) 45.7% (32.8-57.8)

Acute GVHD grade II-IV f

2 years 23.3 % (15.7-33.8) 58.1 % (45.2-71.6) <.01

Acute GVHD grade III-IVf

2 years 8.6% (4.2-17.2) 16.5% (8.9-29.4) .08

Chronic GVHDf

2 years 16.0% (8.1-30.2) 78.4 % (62.6-90.7) <.01

*Cumulative incidence

fKaplan-Meier estimate

CI indicates confidence interval; GVHD, graft-versus-host disease. *To compare the cumulative incidence curves we used the Gray's test. fLog rank test was used to compare the Kaplan Meier curves.

much higher among patients receiving transplant at MDACC. More than half of the surviving patients at MDACC have cGVHD in contrast to only 2 of 37 patients at the UC.

Multivariate Analysis

The relative risks and P values of the remaining independent variables in the multivariate Cox regressions with stepwise model selection are listed in Table 3. TRM was lower in recipients of matched related donor transplants (P < .01). A reduction in TRM in recipients of an alemtuzumab-prepared transplant was not statistically significant (Figure 5). Disease progression was increased with lower doses of Mel, and increased in patients with high-risk disease. Receiving an alemtuzumab-prepared transplant was associated with a trend toward higher relapse risk, but this association was not statistically significant (Figure 6).

High-risk leukemia or MDS and receiving a mismatched or unrelated donor transplant were the only

Figure 1. Survival.

predictors for DFS and OS. Transplant conditioning or GVHD prophylaxis had no significant impact.

The risk for grade II-IV aGVHD was increased with unrelated donor transplant (P = .02) and was decreased with alemtuzumab prepared transplant (relative risk [RR] 5.45, P < .01). The risk for grade III-IV aGVHD was also reduced with the use of alemtuzu-mab, but this reduction was not statistically significant (RR 2.9, P = .08) The risk for cGVHD was reduced more than 6-fold with an alemtuzumab-prepared transplant (RR 6.6, P < .01)

DISCUSSION

Allogeneic transplantation is a curative treatment for patients with advanced leukemia or MDS. Complications of intensive myeloablative conditioning, relapse, and lack of donors have long limited its application to younger patients in excellent condition. Recent improvements, including better selection of unrelated donors [32], better management and prevention of infectious complications [33,34], the development of novel conditioning regimens [11,35,36], as well as newer methods of GVHD prophylaxis have generated considerable interest in extending the use of transplant to older and less fit patients [1-3].

The Flu + Mel regimen initially developed in the mid nineties cures a fraction of patients and has been widely adopted [4-7]. PBSC are commonly used with this regimen in an attempt to hasten immune reconstitution, but have been the cause of a high incidence of extensive cGVHD, which is associated with considerable chronic morbidity and mortality [37]. To reduce the incidence of cGVHD, several centers have used in vivo alemtuzumab with the Flu + Mel conditioning

Figure 2. Progression-Free Survival.

regimen instead of posttransplant MTX [17-20]. This regimen results in a very low incidence of aGVHD and cGVHD, probably because of alemtuzumab's differential effects on host- and donor-antigen presenting cells (APCs) [38,39], as well as on B and T cells, both of which play important effector roles in cGVHD [40]. But many are concerned that the use of alemtuzu-mab will lead to unacceptable rates of disease recurrence and to profound immunosuppression and fatal opportunistic infections. To evaluate the overall impact of alemtuzumab on outcome of transplantation in AML and MDS, we compared the outcome of patients treated on the UC protocol with alemtuzu-mab-based GVHD prophylaxis, with a cohort of patients treated and previously reported from MDACC who received almost identical doses of chemotherapy. All MDACC patients received MTX and tacrolimus, and none received alemtuzumab. Patient and disease characteristics were remarkably similar between the 2 institutions, with nearly half of the patients undergoing unrelated donor transplantation and many patients with advanced hematologic malignancies. The median age of 54 years at both institutions reflects current patterns of patient selected for allogeneic transplantation at U.S. hospitals [1].

The most striking difference between the 2 cohorts is the much reduced incidence of GVHD in patients

Figure 3. Acute GVHD.

Figure 4. Chronic GVHD.

receiving alemtuzumab-based conditioning. This is particularly true for cGVHD, which is nearly 6-fold reduced. This observation is consistent with prior studies of T cell-depleted transplantation using CAMPATH formulations, which indicate a very effective abrogation of cGVHD. The effective prevention of GVHD by in vivo T cell depletion did not lead to an increased incidence of opportunistic infections. Indeed, with aggressive CMV prophylaxis, the incidence of CMV disease was exceedingly low after alemtuzumab conditioning, and other opportunistic infections were rare and often manageable. These observations are also consistent with those from the UK consortium, who report a high incidence of CMV viremia, but few instances of CMV disease [19].

Although aGVHD and cGVHD have been typically associated with decreased recurrence rates, we showed a nonsignificant increase in recurrence rates with alemtuzumab. It remains debatable how important graft-versus-leukemia (GVL) effects are for overall outcome in acute leukemia and MDS [41-46]. The fact that 50% to 60% of patients with early-stage AML survive free of disease after alemtuzumab-based conditioning or after in vitro T cell depletion, with a very low incidence of cGVHD suggests that overt GVHD is not a necessary or desirable component of allogeneic transplantation for AML or MDS [17,20,42-47]. Of interest, lower doses of Mel used in 13 of the MDACC patients was associated with increased risk of disease recurrence in multivariate analysis. This observation lends further credence to the importance ofdose intensity in allogeneic transplant for AML and MDS. The MDACC group previously compared the outcome of Flu-cytarabine-idarubicin (nonablative) with that after Flu + Mel (RIC) and found better disease control with the more dose-intense regimen [4]. In a previous study of a small cohort of older unrelated donor recipients they found a 54% survival after Flu + Mel-180 conditioning compared to 14% with Flu 1 Mel-140 [3]. It is noteworthy that, in contrast to many other studies, none of the patients in either cohort received

Table 3. Multivariate Analysis of Treatment-Related Mortality, Relapse, Progression-Free Survival, and Overall Survival

Variables Relative Risk (95% CI) P-Value

Treatment related mortality

Main effect:

U Chicago 1.00/Referent .3

MDACC 1.44 (0.7-2.9)

Other significant covariates:

Related and matched 0.37 (0.18-0.76) <.01

Relapse

Main effect:

U Chicago 1.00/Referent

MDACC 0.56 (0.3-1.05) .07

Other significant covariates:

Dose 0.2 (0.05-0.75) .01

Risk group 2.67(1.7-4.1) <.01

Progression-free survival

Main effect:

U Chicago 1.00/Referent

MDACC 0.8(0.5-1.3) .3

Other significant covariates:

Risk Group 2.06 (1.5-2.8) <.01

Related and matched 0.6 (0.4-0.9) .03

Overall survival

Main effect:

U Chicago 1.00/Referent

MDACC 0.9 (0.56-1.43) .6

Other significant covariates:

Risk group 2.00(1.45-2.75) <.01

Related and matched 0.6 (0.4-0.9) .02

Acute GVHD Grade II-IV

Main effect:

UC 1.00/Referent

MDACC 5.45 (2.8-10.3) <.01

Other significant covariates:

Related and matched 0.5 (0.28-0.93) .02

Acute GVHD Grade III-IV

Main effect:

U Chicago 1.00/Referent

MDACC 2.9 (0.87-9.5) .08

No significant covariates

Chronic GVHD

Main effect:

UC 1.00/Referent

MDACC 6.6 (2.8-15.4) <.01

No significant covariates

MDACC indicates M.D. Anderson Cancer Center; GVHD, graft-versus-host disease.

Figure 5. Cumulative Probability of Treatment-Related Mortality.

less likely GVHD. It is also possible that there are imbalances in other latent variables that remain unrecognized.

With these caveats in mind, our overall results illustrate the persisting problems of allogeneic transplantation in AML and MDS, but also provide some clues for future research. Approximately one-third of patients obtain durable remissions, but patients with advanced disease are particularly prone to relapse. The use of alemtuzumab has, in our opinion, advantages over MTX-based GVHD prophylaxis, particularly in patients with less advanced AML and MDS, because a higher percentage of patients survive without cGVHD, and rates of disease recurrence are minimally, if at all, affected. This is not the case in all diseases. Similar results have been reported in patients with lymphoma [48], but the UK group in particular has pointed out an increased risk for TRM and opportunistic infections in chronic lymphocytic leukemia (CLL) patients who are prepared for transplant with an alemtuzumab-based regimen, probably because of excessive preexisting

prophylactic DLI for mixed or declining chimerism, thus avoiding any potential effect of adoptive cellular therapies on rates of disease recurrence.

OS and PFS are nearly identical between the alem-tuzumab- and nonalemtuzumab-prepared patients. As in other studies, disease-related factors (summarized here as the risk group) are the most important determinants of OS and PFS. Our data have several limitations related to the retrospective study design. The patients at MDACC were transplanted several years earlier, and high-resolution HLA-typing for class I loci was not yet utilized. This might have had an impact on the incidence of GVHD and of TRM in unrelated donor recipients. Similarly, supportive care particularly relating to antifungal prophylaxis has evolved considerably, and this may have affected TRM, but

Days After Transplantation Figure 6. Cumulative probability of Disease Recurrence.

immunosuppression [49]. Others have found that CML patients and myeloma patients also have a very high risk for disease recurrence [50,51]. Similarly, not all methods of T cell depletion have equal effects on cGVHD. Thymoglobulin-based T cell depletion reduces cGVHD in a fashion similar to alemtuzumab [52], but T cell depletion with the monoclonal 10B9 or with counterflow elutriation does not [53].

The limitations of current conditioning regimens may be addressed in a variety of ways. Selection of patients with less advanced disease, that is, earlier in the course of the disease, represents an attractive option. There are, however, major logistical obstacles to early transplantation, and it is likely that many patients with refractory disease will continue to be referred. Immune manipulations as well as modifications of chemotherapeutic regimens may both be studied to render allogeneic transplantation more effective, and may represent complementary approaches. The development of intensified or more effective drug regimens using optimized dosing schedules and novel drugs such as i.v. Bu, treosulfan, or more recently clofarabine, therefore remain an area of major interest. Decreasing GVHD prophylaxis or its duration is a widely used tool for inducing GVL effects, but can result in unacceptable rates of GVHD. Abrogation of GVHD by in vivo or in vitro T cell depletion may be further fine tuned, for example, by changing the intensity of T cell depletion. Infusions of small doses of donor lymphocytes, or of lymphocyte subsets (regulatory T cell [Treg] depleted, CD8 depleted, natural killer [NK] cells) may be studied in high-risk patients after transplantation. Other approaches, such as immunostimulation with interferon, interleukin 2 (IL2), or other immunomodulators may also be of interest.

ACKNOWLEDGMENTS

Financial disclosure: This work was supported in part by an unrestricted grant from Berlex pharmaceuticals and by NCI Grant 1-R21 CA101337-01. Dr. van Besien is partially supported by grant K24 CA116471.

REFERENCES

1. van Besien K, Artz A, Stock W. Unrelated donor transplantation over the age of 55. Are we merely getting (b)older? Leukemia. 2005;19:31-33.

2. Shimoni A, Kroger N, Zabelina T, et al. Hematopoietic stem-cell transplantation from unrelated donors in elderly patients (age >55 years) with hematologic malignancies: older age is no longer a contraindication when using reduced intensity conditioning. Leukemia. 2005;19:7-12.

3. Wong R, Giralt SA, Martin T, et al. Reduced-intensity conditioning for unrelated donor hematopoietic stem cell transplantation as treatment for myeloid malignancies in patients older than 55 years. Blood. 2003;102:3052-3059.

4. de Lima M, Anagnostopoulos A, Munsell M, et al. Non-ablative versus reduced intensity conditioning regimens in the treatment

of acute myeloid leukemia and high-risk myelodysplastic syndrome. Dose is relevant for long-term disease control after allo-geneic hematopoietic stem cell transplantation. Blood. 2004;104: 865-872.

5. Giralt S, Cohen R, Mehra R, et al. Preliminary results of fludar-abine/melphalan or 2CDA/melphalan as preparative regimens for allogeneic progenitor cell transplantation in poor candidates for myeloablative conditioning [abstract]. Blood. 1997;90(Suppl 1):1853.

6. van Besien K, Devine S, Wickrema A, et al. Fludarabine melphalan is a suitable alternative to fludarabine-TBI based conditioning for allogeneic transplantation in patients with advanced hematologic malignancies [abstract]. HematolJ. 2002;3(Suppl 1):580.

7. van Besien K, Devine S, Wickrema A, et al. Regimen-related toxicity after fludarabine-melphalan conditioning: a prospective study of 31 patients with hematologic malignancies. Bone Marrow Transplant. 2003;32:471-476.

8. Van Besien KW, Demuynck H, LeMaistre CF, Bogaerts MA, Champlin RE. High dose melphalan allows durable engraftment of allogeneic bone marrow. Bone Marrow Transplant. 1995;15: 321-323.

9. Singhal S, Powles R, Treleaven J, et al. Melphalan alone prior to allogeneic bone marrow transplantation from HLA-identical sibling donors for hematologic malignancies: alloengraftment with potential preservation of fertility in women. Bone Marrow Transplant. 1996;18:1049-1055.

10. Gandhi V, Plunkett W. Cellular and clinical pharmacology of fludarabine. Clin Pharmacokinet. 2002;41:93-103.

11. Giralt S, Thall PF, Khouri I, et al. Melphalan and purine analog-containing preparative regimens: reduced-intensity conditioning for patients with hematologic malignancies undergoing allogeneic progenitor cell transplantation. Blood. 2001;97:631-637.

12. Oran B, Giralt S, Saliba R, et al. Allogeneic hematopoietic stem cell transplantation for the treatment of high-risk acute myelogenous leukemia and myelodysplastic syndrome using reduced-intensity conditioning with fludarabine and melphalan. Biol BloodMarrow Transplant. 2007;13:454-462.

13. van Besien KW, Artz A, Smith S, et al. Fludarabine melphalan and alemtuzumab (Campath) conditioning for pts with high risk myeloid malignancies. High cure rate for pts with low leukemia burden. Blood. 2004;104:2321.

14. Morris E, Thomson K, Craddock C, et al. Outcome following alemtuzumab (CAMPATH-1H)-containing reduced intensity allogeneic transplant regimen for relapsed and refractory non-Hodgkin's lymphoma (NHL). Blood. 2004; 104:3865-3871.

15. Chakraverty R, Peggs K, Chopra R, et al. Limiting transplantation-related mortality following unrelated donor stem cell transplantation by using a nonmyeloablative conditioning regimen. Blood. 2002;99:1071-1078.

16. Kottaridis PD, Milligan DW, Chopra R, et al. In vivo CAMPATH-1H prevents graft-versus-host disease following nonmyeloablative stem cell transplantation. Blood. 2000;96: 2419-2425.

17. Tauro S, Craddock C, Peggs K, et al. Allogeneic stem-cell transplantation using a reduced-intensity conditioning regimen has the capacity to produce durable remissions and long-term disease-free survival in patients with high-risk acute myeloid leukemia and myelodysplasia. J Clin Oncol. 2005;23:9387-9393.

18. Avivi I, Chakrabarti S, Milligan DW, et al. Incidence and outcome of adenovirus disease in transplant recipients after reduced-intensity conditioning with alemtuzumab. Biol Blood Marrow Transplant. 2004;10:186-194.

19. Chakrabarti S, Mackinnon S, Chopra R, et al. High incidence of cytomegalovirus infection after nonmyeloablative stem cell transplantation: potential role of Campath-1H in delaying immune reconstitution. Blood. 2002;99:4357-4363.

20. van Besien K, Artz A, Smith S, et al. Fludarabine, melphalan, and alemtuzumab conditioning in adults with standard-risk advanced acute myeloid leukemia and myelodysplastic syndrome. J Clin Oncol. 2005;23:5728-5738.

21. de Lima M, Champlin RE, Thall PF, et al. Phase I/II study of gemtuzumab ozogamicin added to fludarabine, melphalan and allogeneic hematopoietic stem cell transplantation for high-risk CD33 positive myeloid leukemias and myelodysplastic syndrome. Leukemia. 2008;22:258-264.

22. Kline J, Pollyea DA, Stock W, et al. Pre-transplant ganciclovir and post transplant high-dose valacyclovir reduce CMVinfections after alemtuzumab-based conditioning. Bone Marrow Transplant. 2006;37:307-310.

23. Przepiorka D, Weisdorf D, Martin P, et al. Consensus conference on GVHD grading. Bone Marrow Transplant. 1995;15: 825-828.

24. van Besien K. Standardizing chronic graft-versus-host disease. Future Oncol. 2006;2:459-462.

25. Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc. 1958;53:457-481.

26. Bartholomew A, Sher D, Sosler S, et al. Stem cell transplantation eliminates alloantibody in a highly sensitized patient. Transplant. 2001;72:1653-1655.

27. Gooley TA, Leisenring W, Crowley J, Storer BE. Estimation of failure probabilities in the presence of competing risks: new representations of old estimators. Stat Med. 1999;18:695-706.

28. Chappell R. Letter to the editor. Int J Radiat Oncol Biol Phys. 1996;36:988-989.

29. Klein JP, Rizzo JD, Zhang MJ, Keiding N. Statistical methods for the analysis and presentation of the results of bone marrow transplants. Part I: unadjusted analysis. Bone Marrow Transplant. 2001;28:909-915.

30. Sorror ML, Giralt S, Sandmaier BM, et al. Hematopoietic cell transplantation specific comorbidity index as an outcome predictor for patients with acute myeloid leukemia in first remission: combined FHCRC andMDACC experiences. Blood. 2007; 110:4606-4613.

31. Bloomfield CD, Lawrence D, Byrd JC, et al. Frequency of prolonged remission duration after high-dose cytarabine intensification in acute myeloid leukemia varies by cytogenetic subtype. CancerRes. 1998;58:4173-4179.

32. Flomenberg N, Baxter-Lowe LA, Confer D, et al. Impact of HLA class I and class II high resolution matching on outcomes of unrelated donor bone marrow transplantation: HLA-C mismatching is associated with a strong adverse effect on transplant outcome. Blood. 2004;104:1923-1930.

33. Wingard JR, Leather H. A new era of antifungal therapy. Biol Blood Marrow Transplant. 2004;10:73-90.

34. BoeckhM, Nichols WG, Papanicolaou G, et al. Cytomegalovi-rus in hematopoietic stem cell transplant recipients: current status, known challenges, and future strategies. Biol Blood Marrow Transplant. 2003;9:543-558.

35. Sorror ML, Maris MB, Storer B, et al. Comparing morbidity and mortality of HLA-matched unrelated donor hematopoietic cell transplantation after nonmyeloablative and myeloablative conditioning: influence of pretransplantation comorbidities. Blood. 2004;104:961-968.

36. Slavin S, Nagler A, Naparstek E, et al. Nonmyeloablative stem cell transplantation and cell therapy as an alternative to conventional bone marrow transplantation with lethal cytoreduction for the treatment of malignant and nonmalignant hematologic diseases. Blood. 1998;91:756-763.

37. Przepiorka D, Saliba R, Anderlini P, et al. Chronic graft vs host disease after allogeneic stem cell transplantation. Blood. 2001;98: 1695-1700.

38. Ratzinger G, Reagan JL, Heller G, Busam KJ, Young JW. Differential CD52 expression by distinct myeloid dendritic

cell subsets: implications for alemtuzumab activity at the level of antigen presentation in allogeneic graft-host interactions in transplantation. Blood. 2003;101:1422-1429.

39. Klangsinsirikul P, Carter GI, Byrne JL, Hale G, Russell NH. Campath-1 G causes rapid depletion of circulating host dendritic cells (DCs) before allogeneic transplantation but does not delay donor DC reconstitution. Blood. 2002;99:2586-2591.

40. Soiffer R. Immune modulation and chronic graft-versus-host disease. Bone Marrow Transplant. 2008;42(Suppl. 1):S66-S69.

41. Deeg HJ, Appelbaum FR, Storer B, et al. Reduced incidence of acute and chronic graft-versus-host disease (GvHD) without increased relapse in patients with high-risk myeloid disorders given thymoglobulin (THY) as part of the transplant conditioning regimen: a dose-finding study [abstract]. Blood. 2004;104:181.

42. Papadopoulos EB, Carabasi MH, Castro-Malaspina H, et al. T-cell-depleted allogeneic bone marrow transplantation as postremission therapy for acute myelogenous leukemia: freedom from relapse in the absence of graft-versus-host disease. Blood. 1998;91:1083-1090.

43. Soiffer RJ, Fairclough D, Robertson M, et al. CD6-depleted allogeneic bone marrow transplantation for acute leukemia in first complete remission. Blood. 1997;89:3039-3047.

44. Aversa F, Terenzi A, Carotti A, et al. Improved outcome with T-cell-depleted bone marrow transplantation for acute leukemia. J Clin Oncol. 1999;17:1545-1550.

45. Marks DI, Bird JM, Vettenranta K, et al. T cell-depleted unrelated donor bone marrow transplantation for acute myeloid leukemia. Biol Blood Marrow Transplant. 2000;6:646-653.

46. Chakrabarti S, Marks DI. Should we T cell deplete sibling grafts for acute myeloid leukaemia in first remission? Bone Marrow Transplant. 2003;32:1039-1050.

47. Deeg HJ, Storer BE, Boeckh M, et al. Reduced incidence of acute and chronic graft-versus-host disease with the addition of thymoglobulin to a targeted busulfan/cyclophosphamide regimen. Biol Blood Marrow Transplant. 2006;12:573-584.

48. Perez-SimonJA, Kottaridis PD, Martino R, et al. Nonmyeloabla-tive transplantation with or without alemtuzumab: comparison between 2 prospective studies in patients with lymphoprolifera-tive disorders. Blood. 2002;100:3121-3127.

49. Delgado J, Thomson K, Russell N, et al. Results of alemtuzu-mab-based reduced-intensity allogeneic transplantation for chronic lymphocytic leukemia: a British Society of Blood and Marrow Transplantation Study. Blood. 2006;107:1724-1730.

50. Crawley C, Szydlo R, Lalancette M, et al. Outcomes of reduced-intensity transplantation for chronic myeloid leukemia: an analysis of prognostic factors from the Chronic Leukemia Working Party of the EBMT. Blood. 2005;106:2969-2976.

51. Crawley C, Lalancette M, Szydlo R, et al. Outcomes for reduced-intensity allogeneic transplantation for multiple myeloma: an analysis of prognostic factors from the Chronic Leukaemia Working Party of the EBMT. Blood. 2005;105: 4532-4539.

52. Bacigalupo A, Lamparelli T, Barisione G, et al. Thymoglobulin prevents chronic graft-versus-host disease, chronic lung dysfunction, and late transplant-related mortality: long-term follow-up of a randomized trial in patients undergoing unrelated donor transplantation. Biol Blood Marrow Transplant. 2006;12: 560-565.

53. Wagner JE, Thompson JS, Carter SL, Kernan NA. Effect of graft-versus-host disease prophylaxis on 3-year disease-free survival in recipients of unrelated donor bone marrow (T-cell Depletion Trial): a multi-centre, randomised phase II-III trial. Lancet. 2005;366:733-741.