Cyclophosphamide followed by intravenous targeted busulfan for allogeneic hematopoietic cell transplantation: pharmacokinetics and clinical outcomes.

Targeted busulfan ((T)BU) and cyclophosphamide (CY) for allogeneic hematopoietic cell transplantation carries a high risk of sinusoidal obstruction syndrome (SOS) in patients undergoing transplantation for myelofibrosis. We tested the hypothesis that reversing the sequence of administration (from (T)BU/CY to CY/(T)BU) would reduce SOS and day +100 nonrelapse mortality. We enrolled 51 patients with myelofibrosis (n = 20), acute myelogenous leukemia (n = 20), or myelodysplastic syndrome (n = 11) in a prospective trial of CY/(T)BU conditioning for allogeneic hematopoietic cell transplantation. CY 60 mg/kg/day i.v. for 2 days was followed by daily i.v. BU for 4 days, targeted to a concentration at steady state (Css) of 800-900 ng/mL. Compared with (T)BU/CY-conditioned patients, CY/(T)BU-conditioned patients had greater exposure to CY (P < .0001) and less exposure to 4-hydroxycyclophosphamide (P < .0001). Clinical outcomes were compared between cases and controls (n = 271) conditioned with (T)BU/CY for the same indications. In patients with myelofibrosis, CY/(T)BU conditioning was associated with a significantly reduced incidence of SOS (0% versus 30% after (T)BU/CY; P = .006), whereas the incidence of SOS was low in both cohorts with acute myelogenous leukemia/myelodysplastic syndrome. Day +100 mortality was significantly lower in the CY/(T)BU cohort (2% versus 13%; P = .01). CY/(T)BU conditioning had a marked affect on the pharmacokinetics of CY and was associated with significantly lower incidence of SOS and day +100 mortality, suggesting that CY/(T)BU is superior to (T)BU/CY as conditioning for patients with myelofibrosis.

Hypoxia selects for a quiescent, CML stem/leukemia initiating-like population dependent on CBP/catenin transcription.

Hypoxia has been reported to regulate both stem cell maintenance and differentiation. Wnt signaling is also a key regulator in stem cells. The recent discovery of functional cross-regulation between the Wnt pathway and HIF-1α/HIF-2α signaling further highlights the complexity of the role of hypoxia in the regulation of stem cells. In this report we reveal that human CML cell lines treated under hypoxic conditions increase the percentage of leukemia stem/initiating-like cells, as judged by surface marker expression, colony forming ability and quiescence. We demonstrate that differential usage of the Kat3 coactivators, CREBBP/Creb Binding Protein (CBP) and EP300 (p300) by catenin, with increased CBP/catenin signaling at the expense of p300/catenin signaling, is mechanistically correlated with the increase in the leukemia stem/initiating-like population. A specific small molecule inhibitor of CBP/catenin dependent transcription, ICG-001, can reverse these effects further demonstrating the critical involvement of CBP/catenin signaling in enhancing and maintaining the leukemia stem/initiating-like cell population under hypoxic conditions.

Gastrointestinal, hepatobiliary, pancreatic, and iron-related diseases in long-term survivors of allogeneic hematopoietic cell transplantation.

Gastrointestinal and hepatobiliary problems in the second year after allogeneic hematopoietic cell transplant (HCT) are usually a continuation of symptoms of protracted acute graft-versus-host disease (GVHD), chronic GVHD, medication side effects, and infection related to immune suppression. As time passes, as tolerance develops, and as immunity improves, the frequency and severity of these problems wane, but new problems involving the gut and liver may arise, sometimes insidiously and sometimes decades after the transplant. Examples are esophageal strictures related to chronic GVHD, gallstones, cirrhosis caused by chronic hepatitis C, secondary malignancy, and rare cases of pancreatic atrophy. One very common complication of transplantation, iron overload, is often associated with substantial iron accumulation in the liver; however, the most troublesome complications are not hepatic but cardiac and endocrine-related.

National Cancer Institute-National Heart, Lung and Blood Institute/pediatric Blood and Marrow Transplant Consortium First International Consensus Conference on late effects after pediatric hematopoietic cell transplantation: long-term organ damage and dysfunction.

Long-term complications after hematopoietic cell transplantation (HCT) have been studied in detail. Although virtually every organ system can be adversely affected after HCT, the underlying pathophysiology of these late effects remain incompletely understood. This article describes our current understanding of the pathophysiology of late effects involving the gastrointestinal, renal, cardiac, and pulmonary systems, and discusses post-HCT metabolic syndrome studies. Underlying diseases, pretransplantation exposures, transplantation conditioning regimens, graft-versus-host disease, and other treatments contribute to these problems. Because organ systems are interdependent, long-term complications with similar pathophysiologic mechanisms often involve multiple organ systems. Current data suggest that post-HCT organ complications result from cellular damage that leads to a cascade of complex events. The interplay between inflammatory processes and dysregulated cellular repair likely contributes to end-organ fibrosis and dysfunction. Although many long-term problems cannot be prevented, appropriate monitoring can enable detection and organ-preserving medical management at earlier stages. Current management strategies are aimed at minimizing symptoms and optimizing function. There remain significant gaps in our knowledge of the pathophysiology of therapy-related organ toxicities disease after HCT. These gaps can be addressed by closely examining disease biology and identifying those patients at greatest risk for adverse outcomes. In addition, strategies are needed for targeted disease prevention and health promotion efforts for individuals deemed at high risk because of their genetic makeup or specific exposure profile.

A case report of thrombotic thrombocytopenic purpura and severe acute renal failure post non-myeloablative allogeneic peripheral blood stem cell transplantation treated with plasma exchange and hemodialysis.

A 59-year-old-woman received related non-myeloablative allogeneic peripheral blood stem cell transplantation (PBSCT) subsequent to autologous PBSCT in our hospital five years after she was diagnosed as oligo-secretory myeloma. She was admitted to our hospital because of vomiting and grayish diarrhea 4 months after non-myeloablative allogeneic PBSCT (mini-alloPBSCT). Although her initial symptoms improved after admission, she gradually showed thrombocytopenia, anemia, and oliguria during the 2 weeks after admission. Our diagnosis was thrombotic thrombocytopenic purpura (TTP) and acute renal failure (ARF) secondary to mini-alloPBSCT. After cessation of cyclosporine administration, we began to treat her with plasma exchange (PE) and hemodialysis. During the three and a half months after we started PE, the TTP gradually improved. Although PE had been reported to be ineffective for TTP post bone marrow transplantation, we could finally discontinue PE. In contrast, since her anuria continued, she was managed with hemodialysis. One month after PE was started, her activity of von Willebrand factor-cleaving protease was 41% (normal range, >50%) and the ultrasonographic investigation of both kidneys was normal. She could be discharged after four and a half months hospitalization and lived well as an outpatient for a further two months. She died shortly after readmission from multiple organ failure without the relapse of TTP. The patient's clinical course would suggest that TTP post mini-alloPBSCT could be treated with PE in some cases, despite the development of dialysis-requiring severe ARF being a poor prognostic factor.

Human herpesvirus 6 meningoencephalitis in allogeneic hematopoietic stem cell transplant recipients.

We retrospectively investigated the clinical characteristics of human herpesvirus 6 (HHV-6) meningoencephalitis within 100 days after allogeneic hematopoietic stem cell transplantation (HSCT). Of 1148 patients who received transplants between January 1999 and December 2003, 11 patients (0.96%) with HHV-6 meningoencephalitis were identified. Ten of 11 recipients received hematopoietic stem cells from donors other than HLA-identical siblings. Confusion was the most frequent central nervous system (CNS) symptom, and a skin rash with high-grade fever preceded the CNS symptoms in 9 patients. Magnetic resonance imaging of the brain showed an abnormal increased T2 signal in the hypothalamus of 5 patients. Eight patients were treated with ganciclovir, and an improvement of CNS symptoms was obtained in 3 patients; 3 patients treated with acyclovir showed no improvement. Improvement in the meningoencephalitis seemed less frequent in patients with abnormal findings in the hypothalamus than in those without such findings. Because the symptoms of HHV-6 meningoencephalitis mimicked those of cyclosporine- or tacrolimus-induced encephalopathy, the drugs were withdrawn at the onset of CNS symptoms in 10 patients, resulting in the development of grade IV graft-versus-host disease (GVHD) in 5 patients. Three patients died of HHV-6 meningoencephalitis, and 6 died of other causes, including GVHD. In conclusion, HHV-6 meningoencephalitis is a rare but potentially life-threatening complication in patients who undergo allogeneic HSCT. Careful assessment of the clinical findings and the brain may allow early and precise diagnosis of HHV-6 meningoencephalitis and contribute to improving its prognosis.

BCR/ABL activates Rap1 and B-Raf to stimulate the MEK/Erk signaling pathway in hematopoietic cells.

The BCR/ABL fusion tyrosine kinase activates various intracellular signaling pathways, thus causing chronic myeloid leukemia (CML). Here we demonstrate that the inducible expression of BCR/ABL in a murine hematopoietic cell line, TonB210, leads to the activation of the Ras family small GTPase Rap1, which is inhibited by the ABL kinase inhibitor imatinib. The Rap1 activity in a CML cell line, K562, was also inhibited by imatinib. Inhibition of Rap1 activation by a dominant negative mutant of Rap1, Rap1-N17, or SPA-1 inhibited the BCR/ABL-induced activation of Elk-1. BCR/ABL also activated in a kinase activity-dependent manner the B-Raf kinase, which is an effector molecule of Rap1 and a potent activator of the MEK/Erk/Elk-1 signaling pathway. Together, these data suggest that, in addition to the well-established Ras/Raf-1 pathway, BCR/ABL activates the alternative signaling pathway involving Rap1 and B-Raf to activate Erk, which may play important roles in leukemogenesis.

Incapacitating lower limb pain syndrome in cord blood stem cell transplant recipients with calcineurin inhibitor.

Calcineurin-inhibitor induced pain syndrome (CIPS) is a newly described entity with a characteristic feature of sudden onset of severe lower limb pain, and high levels of cyclosporine or tacrolimus may be involved in the pathogenesis. This syndrome is rarely seen in recipients of hematopoietic stem cell transplantation (HSCT) compared with other organ transplant recipients, however, heightened awareness of this complication after HSCT may be needed for hematologists, as misdiagnosis can result in catastrophic consequences. We report herein two cases of lower limb pain syndrome, with some clinical features resembling CIPS, occurring during the early phase of cord blood stem cell transplantation for hematological malignancy.

Acquired gain of an X chromosome as the sole abnormality in the blast crisis of chronic neutrophilic leukemia.

Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative disorder characterized by sustained neutrophilic leukocytosis and absence of the Philadelphia chromosome. Most patients with CNL have normal karyotypes, and no specific cytogenetic abnormality has been identified. We report here a patient with CNL that evolved to myeloid blast crisis. A 73-year-old man was admitted to the hospital because of marked leukocytosis (leukocyte count 112.5 x 10(9)/L with 91% segmented neutrophils) and massive hepatosplenomegaly that was diagnosed as CNL with a normal karyotype. After treatment with hydroxyurea for 7 months, the disease progressed to a blast crisis. Bone marrow showed myeloid hyperplasia with 21% myeloblasts, 15% promyelocytes, and marked dysplastic changes of neutrophils. Blastic cells were positive for CD10, CD13, CD14, CD33, CD34, and HLA-DR. Chromosome analysis of the bone marrow cells showed 46,XY,+X in all 20 metaphase spreads. We reviewed 15 cases of CNL terminating in the blast crisis and confirmed that all cases transformed into myeloid crises and had poor prognoses. Furthermore, to our knowledge, this is the first case showing the acquired gain of an extra X chromosome as a sole abnormality in CNL. The gain of an extra X chromosome may play an important role in the progression from chronic phase to the blast crisis of CNL.