Phase I-II study of clofarabine-melphalan-alemtuzumab conditioning for allogeneic hematopoietic cell transplantation

Results from a multidisciplinary clinic guided by geriatric assessment before stem cell transplantation in older adults

Limitations found on geriatric assessment (GA) track with worse outcomes after hematopoietic cell transplantation (HCT). We report on a multidisciplinary team clinic (MDC), consisting of a cancer-specific GA and a multidisciplinary team of providers, to assess candidacy and create an individualized optimization plan for allogeneic HCT candidates aged ≥60 years and autologous HCT and adoptive T-cell therapy candidates aged ≥70 years. Among the 247 patients evaluated in the MDC, allogeneic HCT candidates comprised the majority (60%), followed by autologous HCT (37%) with occasional older cellular therapy candidates (3%). Almost all patients meeting program-required minimum ages for MDC optimization at our institution were assessed (98%). Relative to historical control subjects undergoing GA alone, allogeneic HCT patients aged ≥60 years who underwent MDC appraisal had similar frequencies of high-risk disease, reduced intensity regimens, and high comorbidity but fewer GA-graded functional impairments. The MDC cohort experienced fewer inpatient deaths, shorter length of stay, and fewer discharges to nursing facilities compared with control subjects. Improvements in early mortality were observed over time; 1-year overall survival improved from 43% in the pre-MDC era to 70% in the recent MDC era, and 1-year nonrelapse mortality decreased from 43% to 18%. The 31 autologous HCT recipients aged ≥70 years optimized by the MDC achieved 0% nonrelapse mortality and 97% overall survival at 1 year. A GA-guided MDC for older HCT candidates is feasible and seems to reduce transplant-associated morbidity and mortality. An MDC should encourage broader and safer utilization of transplantation in older patients.

Nephrotoxicity in cancer treatment: An overview

Anticancer drug nephrotoxicity is an important and increasing adverse drug event that limits the efficacy of cancer treatment. The kidney is an important elimination pathway for many antineoplastic drugs and their metabolites, which occurs by glomerular filtration and tubular secretion. Chemotherapeutic agents, both conventional cytotoxic agents and molecularly targeted agents, can affect any segment of the nephron including its microvasculature, leading to many clinical manifestations such as proteinuria, hypertension, electrolyte disturbances, glomerulopathy, acute and chronic interstitial nephritis, acute kidney injury and at times chronic kidney disease. The clinician should be alert to recognize several factors that may maximize renal dysfunction and contribute to the increased incidence of nephrotoxicity associated with these drugs, such as intravascular volume depletion, the associated use of nonchemotherapeutic nephrotoxic drugs (analgesics, antibiotics, proton pump inhibitors, and bone-targeted therapies), radiographic ionic contrast media or radiation therapy, urinary tract obstruction, and intrinsic renal disease. Identification of patients at higher risk for nephrotoxicity may allow the prevention or at least reduction in the development and severity of this adverse effect. Therefore, the aim of this brief review is to provide currently available evidences on oncologic drug-related nephrotoxicity.

Phase I/II multisite trial of optimally dosed clofarabine and low-dose TBI for hematopoietic cell transplantation in acute myeloid leukemia

Clofarabine is an immunosuppressive purine nucleoside analog that may have better anti-leukemic activity than fludarabine. We performed a prospective phase I/II multisite trial of clofarabine with 2 Gy total body irradiation as non-myeloablative conditioning for allogeneic hematopoietic cell transplantation in adults with acute myeloid leukemia who were unfit for more intense regimens. Our main objective was to improve the 6-month relapse rate following non-myeloablative conditioning, while maintaining historic rates of non-relapse mortality (NRM) and engraftment. Forty-four patients, 53 to 74 (median: 69) years, were treated with clofarabine at 150 to 250 mg/m² , of whom 36 were treated at the maximum protocol-specified dose. One patient developed multifactorial acute kidney injury and another developed multiorgan failure, but no other grade 3 to 5 non-hematologic toxicities were observed. All patients fully engrafted. The 6-month relapse rate was 16% (95% CI, 5%-27%) among all patients and 14% (95% CI, 3%-26%) among high-risk patients treated at the maximum dose, meeting the pre-specified primary efficacy endpoint. Overall survival was 55% (95% CI, 40%-70%) and leukemia-free survival was 52% (95% CI, 37%-67%) at 2 years. Compared to a historical high-risk cohort treated with the combination of fludarabine at 90 mg/m² and 2 Gy TBI, protocol patients treated with the clofarabine-TBI regimen had lower rates of overall mortality (HR of 0.50, 95% CI, 0.28-0.91), disease progression or death (HR 0.48, 95% CI, 0.27-0.85), and morphologic relapse (HR 0.30, 95% CI, 0.13-0.69), and comparable NRM (HR 0.85, 95% CI 0.36-2.00). The combination of clofarabine with TBI warrants further investigation in patients with high-risk AML.

Clofarabine and Treosulfan as Conditioning for Matched Related and Unrelated Hematopoietic Stem Cell Transplantation: Results from the Clo3o Phase II Trial

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) can be curative for patients with hematologic malignancies. The ideal conditioning regimen before allo-HSCT has not been established. We conducted a Phase II study to evaluate the tolerability and efficacy of clofarabine and treosulfan as conditioning regimen before allo-HSCT. The primary objective was to evaluate the cumulative incidence of nonrelapse mortality (NRM) on day +100. Forty-four patients (36 with acute myelogenous leukemia, 5 with acute lymphoblastic leukemia, 3 with myelodysplastic syndromes) were enrolled. The median patient age was 47 years, and the median duration of follow-up was 27 months. The conditioning regimen was based on clofarabine 40 mg/m² (days -6 to -2) and treosulfan 14 g/m² (days -6 to -4). Allogeneic hematopoietic stem cells were derived from a sibling (n = 22) or a well-matched unrelated donor (n = 22). Graft-versus-host disease (GVHD) prophylaxis consisted of antithymocyte globulin, rituximab, cyclosporine, and a short-course of methotrexate. The regimen allowed for rapid engraftment and a 100-day NRM of 18%, due mainly to bacterial infections. The incidences of grade II-IV acute GVHD and chronic GVHD were 16% and 19%, respectively. The rates of overall survival (OS), progression-free survival, and relapse at 2 years were 51%, 31%, and 50%, respectively. Significantly different outcomes were observed between patients with low-intermediate and patients with high-very high Disease Risk Index (DRI) scores (1-year OS, 78% and 24%, respectively). Our findings show that the use of treosulfan and clofarabine as a conditioning regimen for allo-HSCT is feasible, with a 78% 1-year OS in patients with a low-intermediate DRI score. However, 1-year NRM was 18%, and despite the intensified conditioning regimen, relapse incidence remains a major issue in patients with poor prognostic risk factors.

Haploidentical Donor Transplantation Using a Novel Clofarabine-containing Conditioning Regimen for Very High-risk Hematologic Malignant Neoplasms

Recurrent/refractory hematologic malignancies have a poor prognosis, and there is a need for novel treatment regimens that can be tolerated by this heavily pretreated patient group. Clofarabine has antileukemic activity with an acceptable toxicity profile. In a phase I clinical trial (NCT00824135), we substituted clofarabine for fludarabine in a well-established reduced-intensity conditioning regimen for a T cell-depleted, mismatched-related (haploidentical) donor transplant backbone and explored the maximum tolerated dose of clofarabine in this combination in 15 patients undergoing hematopoietic cell transplantation for recurrent/refractory or secondary leukemia. Clofarabine was well tolerated at a dose of 50 mg/m/d for 5 days in this regimen, with minimal treatment-related mortality in a heavily pretreated group of high-risk patients. All patients exhibited quick hematopoietic recovery, with median times to neutrophil and platelet engraftment being 11 and 16 days, respectively. Transient elevation of transaminases was the most common toxicity-observed in 13 patients (86.7%), with 6 (40%) grade III or above. Three patients (20%) developed hepatic veno-occlusive disease. Eleven patients (73.3%) died, with the most common cause of death being disease relapse (in 9 patients [60%]), followed by treatment-related mortality (in 2 patients [13.3%]). Four (26.6%) of the patients are long-term survivors.

Impact of pharmacokinetics on the toxicity and efficacy of clofarabine in patients with relapsed or refractory acute myeloid leukemia

Common side effects of clofarabine (CFB) are liver toxicity, particularly a transient elevation of transaminases and skin toxicity. We studied the correlation of pharmacokinetic (PK) parameters with these toxicities and the efficacy of CFB in patients with relapsed or refractory acute myeloid leukemia. Clofarabine PK parameters showed large inter-individual variability. A higher CFB area under the curve was significantly associated with higher transaminase levels (p = .011 for aspartate aminotransferase (AST), adjusted for age, sex, cumulated CFB dosage, baseline AST, and glomerular filtration rate (GFR)). No significant association could be found between maximum concentration and the liver toxicity parameters. The occurrence of skin toxicity and the response to re-induction chemotherapy evaluated at day 15 were also not associated with PK. In conclusion, a higher individual CFB exposure is associated with increased liver toxicity reflected by elevated liver enzymes, without having an impact on anti-leukemic efficacy.

Treating adults with acute lymphocytic leukemia: new pharmacotherapy options

INTRODUCTION

Advances in acute lymphocytic leukemia (ALL) therapy has led to long-term survival rates in children. However, only 30%-40% of adults achieve long-term disease-free survival. After relapse, the outcome of salvage chemotherapy is very disappointing with less than 10% of long survival. Novel agents are therefore desperately required to improve response rates and survival, but also the quality of life of patients. Areas covered: The following review is a comprehensive summary of various novel options reported over the past few years in the therapeutic area of adult ALL. Expert opinion: Identifying key components involved in disease pathogenesis may lead to new approaches. In a near future, the incorporation of monoclonal antibodies and T-cell directed approaches including blinatumomab and chimeric antigen receptor T cells may increase the cure rates and may reduce the need for intensive therapy.

Haploidentical Bone Marrow Transplantation With Clofarabine and Busulfan Conditioning for a Child With Multiple Recurrent Acute Lymphoblastic Leukemia

Outcome of children with acute lymphoblastic leukemia (ALL) has improved over the years, but not for those with multiple recurrences because of high therapy resistance and heavily pretreated history that potentially cause physical damages. We describe the case of an 11-year-old boy with a third relapse of ALL and a history of 2 allogeneic bone marrow transplantations. He was successfully treated with clofarabine combination chemotherapy and achieved a fourth remission at 16 months following haploidentical bone marrow transplantation with conditioning regimen of clofarabine and busulfan. Clofarabine/busulfan conditioning might be a preferable option for children with multiple recurrent ALL, and warrants further investigation.

[Control study of melphalan instead of cyclophosphamide as a myeloablative conditioning regimen for allogeneic hematopoietic stem cell transplantation for treatment of myeloid malignancies]

目的

评价以马法兰(Mel)替代改良白消安(Bu)＋环磷酰胺(Cy)(Bu/Cy)方案中Cy的预处理方案在异基因造血干细胞移植(allo-HSCT)治疗恶性髓系血液病中的有效性及安全性。

方法

分析94例进行allo-HSCT的恶性髓系血液病患者临床资料，其中48例采用Bu+Cy＋氟达拉滨(Flu)＋阿糖胞苷(Ara-C)(BCFA)方案预处理，46例采用Bu+Mel+Flu+ Ara-C (BMFA)方案预处理。移植后观察比较两组预处理方案相关不良反应、植入率、移植物抗宿主病(GVHD)、感染发生、非复发死亡(NRM)率以及总生存(OS)率。

结果

两组患者均获得中性粒细胞成功植入。BMFA组Ⅲ~Ⅳ度口腔溃疡以及腹泻发生率均高于BCFA组(P<0.05)，BMFA组急性GVHD(aGVHD)发生率较高，但差异无统计学意义(36.5％对56.5%，P=0.100)。中位随访42个月，BCFA组和BMFA组NRM率分别为12.5％和19.6% (P=0.400)。BMFA组复发率显著低于BCFA组，分别为4.3％和25.0%(P=0.009)。两组OS率分别为(71.8±6.7)％和(76.1±6.3)%(P=0.852)，无病生存(DFS)率分别为(67.8±8.9)％和(76.1±6.3)%(P=0.567)，BCFA组均略低于BMFA组，但差异均无统计学意义。

结论

应用Mel替代Cy的预处理方案治疗恶性髓系血液病复发率较低，并获得较满意的DFS率，但应注意预处理相关毒性的预防及aGVHD的治疗和干预。

Clofarabine salvage therapy before allogeneic hematopoietic stem cell transplantation in patients with relapsed or refractory AML: results of the BRIDGE trial

In patients with relapsed or refractory (r/r) acute myeloid leukemia (AML), long-term disease control can only be achieved by allogeneic hematopoietic stem cell transplantation (HSCT). We studied the safety and efficacy of clofarabine-based salvage therapy. The study was designed as phase II, multicenter, intent-to-transplant (ITT) study. A total of 84 patients with r/r AML were enrolled. All patients received at least one cycle of CLARA (clofarabine 30 mg/m(2) and cytarabine 1 g/m(2), days 1-5). Chemo-responsive patients with a donor received HSCT in aplasia after first CLARA. Generally, HSCT was performed as soon as possible. The conditioning regimen consisted of clofarabine (4 × 30 mg/m(2)) and melphalan (140 mg/m(2)). The median patient age was 61 years (range 40-75). On day 15 after start of CLARA, 26% of patients were in a morphologically leukemia-free state and 79% exposed a reduction in bone marrow blasts. Overall, 67% of the patients received HSCT within the trial. The primary end point, defined as complete remission after HSCT, was achieved by 60% of the patients. According to the ITT, overall survival at 2 years was 43% (95% confidence interval (CI), 32-54%). The 2-year disease-free survival for transplanted patients was 52% (95% CI, 40-69%). Clofarabine-based salvage therapy combined with allogeneic HSCT in aplasia shows promising results in patients with r/r AML.

Phase II Trial of Reduced-Intensity Busulfan/Clofarabine Conditioning with Allogeneic Hematopoietic Stem Cell Transplantation for Patients with Acute Myeloid Leukemia, Myelodysplastic Syndromes, and Acute Lymphoid Leukemia

Clofarabine has potent antileukemia activity and its inclusion in reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (HSCT) for acute leukemia could potentially improve outcomes. We conducted a phase II study of busulfan (.8 mg/kg i.v. twice daily on days -5, -4, -3, and -2) with clofarabine (40 mg/m(2) i.v. daily on days -5, -4, -3, and -2) conditioning before allogeneic 8/8 HLA-matched related or unrelated HSCT. The primary endpoint was donor neutrophil engraftment by day +40. Secondary endpoints included nonrelapse mortality (NRM), acute and chronic graft-versus-host disease (GVHD), progression-free survival (PFS), and overall survival (OS). Thirty-four patients (acute myeloid leukemia [AML], n = 25; myelodysplastic syndromes, n = 5; and acute lymphoid leukemia, n = 4) were enrolled. Day 40+ engraftment with donor chimerism was achieved in 33 of 34 patients with 1 patient dying before count recovery. Day 100 and 1-year NRM were 5.9% (95% confidence interval [CI], 1.0 to 17.4) and 24% (95% CI, 11 to 39), respectively. The 2-year relapse rate was 26% (95% CI, 13 to 42). Cumulative incidences of acute and chronic GVHD were 21% and 44%, respectively. The 2-year PFS was 50% (95% CI, 32 to 65) and OS was 56% (95% CI, 38 to 71). For patients with AML in first complete remission, 2-year PFS and OS were both 82% (95% CI, 55 to 94). RIC with busulfan and clofarabine leads to successful engraftment with acceptable rates of NRM and GVHD.

Reduced-intensity conditioned allogeneic SCT in adults with AML

AML is currently the most common indication for reduced-intensity conditioned (RIC) allo-SCT. Reduced-intensity regimens allow a potent GVL response to occur with minimized treatment-related toxicity in patients of older age or with comorbidities that preclude the use of myeloablative conditioning. Whether RIC SCT is appropriate for younger and more standard risk patients is not well defined and the field is changing rapidly; a prospective randomized trial of myeloablative vs RIC (BMT-CTN 0901) was recently closed when early results indicated better outcomes for myeloablative regimens. However, detailed results are not available, and all patients in that study were eligible for myeloablative conditioning. RIC transplants will likely remain the standard of care as many patients with AML are not eligible for myeloablative conditioning. Recent publication of mature results from retrospective and prospective cohorts provide contemporary efficacy and toxicity data for these attenuated regimens. In addition, recent studies explore the use of alternative donors, introduce regimens that attempt to reduce toxicity without reducing intensity, and identify predictive factors that pave the way to personalized approaches. These studies paint a picture of the future of RIC transplants. Here we review the current status of RIC allogeneic SCT in AML.

The role of Clofarabine in the treatment of adults with acute myeloid leukemia

The therapeutic scenario available for adult patients with acute myeloid leukemia (AML) has shown only partial progresses over the last few years. This is especially true for refractory and relapsed AML whose outcome is still extremely disappointing. In this context Clofarabine has offered new promising perspectives within first and second line protocols. This review will firstly describe the initial development in monotherapy, considering then the different potential combination strategies which include both polichemotherapeutic regimens and less conventional approaches with new generation drugs. The potential use of Clofarabine as induction treatment for patients candidate to stem cell transplantation and within conditioning regimens will be finally evaluated.

[Current indications of allogeneic stem cell transplant in adults with acute myeloid leukemia]

Allogeneic stem cell transplantation (SCT) is an increasingly important therapeutic option for the treatment of adult patients with acute myeloid leukemia. Here we review the current indications of SCT in this disease. While patients with favorable cytogenetics should receive consolidation chemotherapy, patients with unfavorable karyotype are prime candidates for SCT or new approaches to SCT (which should be done in first complete remission). Patients with intermediate prognoses should also receive SCT in first complete remission. In the absence of a suitable matched related donor, most patients will be able to find an alternative donor to proceed to a potentially curative allogeneic transplantation. The use of reduced-intensity conditioning regimens before SCT has allowed patients in the sixth or seventh decades of life to be routinely transplanted. Despite major differences among transplant centers in the intensity and composition of the conditioning regimen and immunosuppression, choice of graft source, postgraft immune-modulation, and supportive care, there has been a dramatic improvement in terms of tolerance. Although it is presumed to be a curative strategy, major complications of SCT remain graft-versus-host disease, delayed immune recovery, multiple comorbidities, and relapse after transplant.

Similar transplantation outcomes for acute myeloid leukemia and myelodysplastic syndrome patients with haploidentical versus 10/10 human leukocyte antigen-matched unrelated and related donors

Allogeneic stem cell transplantation for patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) has been performed primarily with an HLA-matched donor. Outcomes of haploidentical transplantation have recently improved, and a comparison between donor sources in a uniform cohort of patients has not been performed. We evaluated outcomes of 227 patients with AML/MDS treated with melphalan-based conditioning. Donors were matched related (MRD) (n = 87, 38%), matched unrelated (MUD) (n = 108, 48%), or haploidentical (n = 32, 14%). No significant differences were found between haploidentical and MUD transplantation outcomes; however, there was a trend for improved outcomes in the MRD group, with 3-year progression-free survival for patients in remission of 57%, 45%, and 41% for MRD, MUD, and haploidentical recipients, respectively (P = .417). Recovery of T cell subsets was similar for all groups. These results suggest that haploidentical donors can safely extend transplantation for AML/MDS patients without an HLA-matched donor. Prospective studies comparing haploidentical and MUD transplantation are warranted.

Results from a clofarabine-busulfan-containing, reduced-toxicity conditioning regimen prior to allogeneic stem cell transplantation: the phase 2 prospective CLORIC trial

We prospectively evaluated the safety and efficacy of a clofarabine, intravenous busulfan and antithymocyte globulin-based reduced-toxicity conditioning (CloB2A2) regimen before allogeneic stem cell transplantation. Thirty high-risk patients (median age: 59 years; acute myeloid leukemia n=11, acute lymphoblastic leukemia n=13; myelodysplastic syndrome n=5, bi-phenotypic leukemia n=1) were included in this phase 2 study. At time of their transplant, 20 and seven patients were in first and second complete remission, respectively, while three patients with myelodysplastic syndrome were responding to chemotherapy or who had not been previously treated. The CloB2A2 regimen consisted of clofarabine 30 mg/m(2)/day for 4 days, busulfan 3.2 mg/kg/day for 2 days and antithymocyte globulin 2.5 mg/kg/day for 2 days. The median follow-up was 23 months. Engraftment occurred in all patients. The 1-year overall survival, leukemia-free survival, relapse incidence and non-relapse mortality rates were 63±9%, 57±9%, 40±9%, and 3.3±3%, respectively. Comparing patients with acute myeloid leukemia/myelodysplastic syndrome versus those with acute lymphoblastic leukemia/bi-phenotypic leukemia, the 1-year overall and leukemia-free survival rates were 75±10% versus 50±13%, respectively (P=0.07) and 69±12% versus 43±13%, respectively (P=0.08), while the 1-year relapse incidence was 25±11% versus 57±14%, respectively (P=0.05). The CloB2A2 regimen prior to allogeneic stem cell transplantation is feasible, allowing for full engraftment and low toxicity. Disease control appears to be satisfactory, especially in patients with acute myeloid leukemia/myelodysplastic syndrome. The trial was registered at www.clinicaltrials.gov no. NCT00863148.

Conditioning regimens for hematopoietic cell transplantation: one size does not fit all

An essential component of allogeneic and autologous hematopoietic cell transplantation (HCT) is the conditioning regimen administered before the hematopoietic cell infusion. Early regimens relied on dose intensity, assuming that high-dose chemoradiotherapy would eliminate malignant disease and reinfusion of the graft would then restore hematopoiesis. However, as the contribution of graft-versus-tumor effects to the success of allogeneic HCT was recognized over time, in an effort to exploit these, many investigators lowered the dose of radiation and chemotherapeutic agents in the preparative regimen. This resulted in a major paradigm shift, and consequently, the pool of eligible patients underwent a remarkable expansion. In this article, we provide a review of the definition of high-dose, reduced-intensity, and nonmyeloablative conditioning regimens, the most commonly used agents and combinations, and the evolution of some early regimens. We also provide a brief review of the toxicities associated with these regimens.

Clofarabine-associated acute kidney injury in patients undergoing hematopoietic stem cell transplant

Abstract We examined clofarabine pharmacokinetics and association with renal toxicity in 62 patients participating in a phase I-II study of clofarabine-melphalan-alemtuzumab conditioning for hematopoietic stem cell transplant (HSCT). Pharmacokinetic parameters, including clofarabine area under the concentration-time curve (AUC), maximum concentration and clearance, were measured, and patients were monitored for renal injury. All patients had normal pretreatment creatinine values, but over half (55%) experienced acute kidney injury (AKI) after clofarabine administration. Age was the strongest predictor of AKI, with older patients at greater risk (p = 0.002). Clofarabine AUC was higher in patients who developed AKI, and patients with the highest dose-normalized AUCs experienced the most severe grades of AKI (p = 0.01). Lower baseline renal function, even when normal, was associated with lower clofarabine clearance (p = 0.008). These data suggest that renal-adjustment of clofarabine dosing should be considered for older and at-risk patients even when renal function is ostensibly normal.

Conditioning chemotherapy dose adjustment in obese patients: a review and position statement by the American Society for Blood and Marrow Transplantation practice guideline committee

Hematopoietic stem cell transplantation (HCT) is a potentially life-saving therapy for patients with malignant and nonmalignant disease states. This article reviews the current published literature on the dosing of pharmacologic agents used for HCT preparative regimens with specific focus on the obese patient population. The review found that dose adjustments for obesity have, to date, been based empirically or extrapolated from published data in the nontransplantation patient population. As a result, the Committee determined that clear standards or dosing guidelines are unable to be made for the obese population because Level I and II evidence are unavailable at this time. Instead, the Committee provides a current published literature review to serve as a platform for conditioning agent dose selection in the setting of obesity. A necessary goal should be to encourage future prospective trials in this patient population because further information is needed to enhance our knowledge of the pharmacokinetics and pharmacodynamics of conditioning agents in the setting of obesity.

Preparative regimen dosing for hematopoietic stem cell transplantation in patients with chronic kidney disease: analysis of the literature and recommendations

Hematopoietic stem cell transplantation (HSCT) is a potentially life-saving therapy that has traditionally been associated with high treatment-related mortality due to direct regimen toxicity and a high incidence of graft-versus-host disease. Historically, pre-existing renal insufficiency has been considered an exclusion criterion for transplantation. The advent of nonmyeloablative conditioning regimens as a less toxic modality for treatment has made HSCT more accessible to elderly patients and patients with comorbidities, such as renal impairment. However, there is no clear standard for how to dose preparative regimens for patients with chronic renal impairment who undergo HSCT. This article serves as a review of the current literature to provide dosing recommendations for commonly used preparative agents in the setting of chronic kidney disease, with the aim of providing optimal dosing for this patient population.

A novel clofarabine bridge strategy facilitates allogeneic transplantation in patients with relapsed/refractory leukemia and high-risk myelodysplastic syndromes

Patients with relapsed/refractory leukemias or advanced myelodysplastic syndrome (MDS) fare poorly following allogeneic hematopoietic cell transplant (HCT). We report prospective phase II study results of 29 patients given clofarabine 30 mg/m(2)/day i.v. × 5 days followed immediately by HCT conditioning while at the cytopenic nadir. A total of 15/29 patients (52%) were cytoreduced according to pre-defined criteria (cellularity <20% and blasts <10%). Marrow cellularity (P<0.0001) and blast% (P=0.03) were reduced. Toxicities were acceptable, with transient hyperbilirubinemia (48%) and gr3-4 infections (10%). In all, 28/29 proceeded to transplant; 27 received ATG or alemtuzumab. Post HCT, 180 day non-relapse mortality (NRM) was 7% (95% confidence interval (CI): 1-21), relapse was 29% (95% CI: 13-46) and OS was 71% (95% CI: 51-85), comparing favorably to published data for high-risk patients. Two-year graft vs host disease incidence was 40% (95% CI: 21-58) and 2 year OS was 31% (95% CI: 14-48). Disease at the nadir correlated with inferior OS after HCT (HR=1.22 for each 10% marrow blasts, 95% CI: 1.02-1.46). For AML/MDS patients, there was a suggestion that successful cytoreduction increased PFS (330 vs 171 days, P=0.3) and OS (375 vs 195 days, P=0.31). Clofarabine used as a bridge to HCT reduces disease burden, is well tolerated, and permits high-risk patients to undergo HCT with acceptable NRM. Late relapses are common; thus, additional strategies should be pursued. NCT-00724009.

Genetic and epigenetic variants contributing to clofarabine cytotoxicity

2-chloro-2-fluoro-deoxy-9-D-arabinofuranosyladenine (Clofarabine), a purine nucleoside analog, is used in the treatment of hematologic malignancies and as induction therapy for stem cell transplantation. The discovery of pharmacogenomic markers associated with chemotherapeutic efficacy and toxicity would greatly benefit the utility of this drug. Our objective was to identify genetic and epigenetic variants associated with clofarabine toxicity using an unbiased, whole genome approach. To this end, we employed International HapMap lymphoblastoid cell lines (190 LCLs) of European (CEU) or African (YRI) ancestry with known genetic information to evaluate cellular sensitivity to clofarabine. We measured modified cytosine levels to ascertain the contribution of genetic and epigenetic factors influencing clofarabine-mediated cytotoxicity. Association studies revealed 182 single nucleotide polymorphisms (SNPs) and 143 modified cytosines associated with cytotoxicity in both populations at the threshold P ≤ 0.0001. Correlation between cytotoxicity and baseline gene expression revealed 234 genes at P ≤ 3.98 × 10(-6). Six genes were implicated as: (i) their expression was directly correlated to cytotoxicity, (ii) they had a targeting SNP associated with cytotoxicity, and (iii) they had local modified cytosines associated with gene expression and cytotoxicity. We identified a set of three SNPs and three CpG sites targeting these six genes explaining 43.1% of the observed variation in phenotype. siRNA knockdown of the top three genes (SETBP1, BAG3, KLHL6) in LCLs revealed altered susceptibility to clofarabine, confirming relevance. As clofarabine's toxicity profile includes acute kidney injury, we examined the effect of siRNA knockdown in HEK293 cells. siSETBP1 led to a significant change in HEK293 cell susceptibility to clofarabine.

Pharmacological methods to reduce disease recurrence

Allogeneic stem cell transplantation is an increasingly important treatment option in patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Although there has been substantial progress in reducing transplantation-related mortality (TRM), little progress has been made in reducing the risk of disease relapse, which continues to represent the major cause of treatment failure in patients allografted for AML and MDS. Experience with myeloablative conditioning regimens has demonstrated that, although intensification of the preparative regimen reduces relapse risk, any survival benefit is blunted by a concomitant increase in TRM. A similar inverse correlation between relapse risk and TRM is observed in patients allografted using a reduced-intensity conditioning regimen. However, the markedly lower toxicity of such regimens has permitted the design of novel conditioning strategies aimed at maximizing antitumor activity without excessive transplant toxicity. Coupled with recent advances in drug delivery and design, this has allowed the development of a spectrum of new conditioning regimens in patients with high-risk AML and MDS. At the same time, the optimization of a graft-versus-leukemia (GVL) effect by minimizing posttransplantation immunosuppression, with or without the infusion of donor lymphocytes, is essential if the risk of disease relapse is to be reduced. Recently, the delivery of adjunctive posttransplantation therapies has emerged as a promising method of augmenting antileukemic activity, either through a direct antitumor activity or consequent upon pharmacological manipulation of the alloreactive response. Taken together these advances present a realistic possibility of delivering improved outcome in patients allografted for high-risk AML or MDS.

Fifty years of melphalan use in hematopoietic stem cell transplantation

Melphalan remains the most widely used agent in preparative regimens for hematopoietic stem cell transplantation (SCT). From its initial discovery more than 50 years ago, it has been gradually incorporated in the conditioning regimens for both autologous and allogeneic transplantations because of its myeloablative properties and broad antitumor effects as a DNA alkylating agent. Melphalan remains the mainstay conditioning for multiple myeloma and lymphomas, and it has been used successfully in preparative regimens of a variety of other hematological and nonhematological malignancies. The addition of newer agents to conditioning, such as bortezomib or lenalidomide for myeloma or clofarabine for myeloid malignancies, may improve antitumor effects for transplantation, whereas melphalan in combination with alemtuzumab may represent a backbone for future cellular therapy because of reliable engraftment and low toxicity profile. This review summarizes the development and the current use of this remarkable drug in hematopoietic SCT.