Pulmonary hypertension complicating bone marrow transplantation for idiopathic myelofibrosis

Long-Term Health Effects of Curative Therapies on Heart, Lungs, and Kidneys for Individuals with Sickle Cell Disease Compared to Those with Hematologic Malignancies

The goal of curing children and adults with sickle cell disease (SCD) is to maximize benefits and minimize intermediate and long-term adverse outcomes so that individuals can live an average life span with a high quality of life. While greater than 2000 individuals with SCD have been treated with curative therapy, systematic studies have not been performed to evaluate the long-term health effects of hematopoietic stem cell transplant (HSCT) in this population. Individuals with SCD suffer progressive heart, lung, and kidney disease prior to curative therapy. In adults, these sequalae are associated with earlier death. In comparison, individuals who undergo HSCT for cancer are heavily pretreated with chemotherapy, resulting in potential acute and chronic heart, lung, and kidney disease. The long-term health effects on the heart, lung, and kidney for children and adults undergoing HSCT for cancer have been extensively investigated. These studies provide the best available data to extrapolate the possible late health effects after curative therapy for SCD. Future research is needed to evaluate whether HSCT abates, stabilizes, or exacerbates heart, lung, kidney, and other diseases in children and adults with SCD receiving myeloablative and non-myeloablative conditioning regimens for curative therapy.

Infantile Myelofibrosis and Myeloproliferation with CDC42 Dysfunction

Studies of genetic blood disorders have advanced our understanding of the intrinsic regulation of hematopoiesis. However, such genetic studies have only yielded limited insights into how interactions between hematopoietic cells and their microenvironment are regulated. Here, we describe two affected siblings with infantile myelofibrosis and myeloproliferation that share a common de novo mutation in the Rho GTPase CDC42 (Chr1:22417990:C>T, p.R186C) due to paternal germline mosaicism. Functional studies using human cells and flies demonstrate that this CDC42 mutant has altered activity and thereby disrupts interactions between hematopoietic progenitors and key tissue microenvironmental factors. These findings suggest that further investigation of this and other related disorders may provide insights into how hematopoietic cell-microenvironment interactions play a role in human health and can be disrupted in disease. In addition, we suggest that deregulation of CDC42 may underlie more common blood disorders, such as primary myelofibrosis.

Myeloproliferative Neoplasms in Children

Myeloproliferative neoplasms (MPN) are a group of clonal hematopoietic stem cell disorders characterized by aberrant proliferation of one or more myeloid lineages often with increased immature cells in the peripheral blood. The three classical BCR-ABL-negative MPNs are: 1) polycythemia vera (PV), 2) essential thrombocythemia (ET), and 3) primary myelofibrosis (PMF), which are typically disorders of older adults and are exceedingly rare in children. The diagnostic criteria for MPNs remain largely defined by clinical, laboratory and histopathology assessments in adults, but they have been applied to the pediatric population. The discovery of the JAK2 V617F mutation, and more recently, MPL and CALR mutations, are major landmarks in the understanding of MPNs. Nevertheless, they rarely occur in children, posing a significant diagnostic challenge given the lack of an objective, clonal marker. Therefore, in pediatric patients, the diagnosis must rely heavily on clinical and laboratory factors, and exclusion of secondary disorders to make an accurate diagnosis of MPN. This review focuses on the clinical presentation, diagnostic work up, differential diagnosis, treatment and prognosis of the classical BCR-ABL-negative MPNs (PV, ET and PMF) in children and highlights key differences to the adult diseases. Particular attention will be given to pediatric PMF, as it is the only disorder of this group that is observed in infants and young children, and in many ways appears to be a unique entity compared to adult PMF.

VPS 45-associated primary infantile myelofibrosis--successful treatment with hematopoietic stem cell transplantation

PMF of infancy is a recently described autosomal recessive disorder presenting with severe bone marrow failure, accelerated neutrophil apoptosis, and significant platelet dysfunction, caused by a mutation in the VPS45 gene. In this study, we update our group of patients with PMF, highlighting different aspects of this disease, and evaluating the effectiveness of HSCT for the treatment of this disorder. Update of clinical data, hematological features, molecular studies, treatment and final outcome of four children diagnosed with VPS 45-associated PMF of infancy. The patients described had clinical and hematological findings consistent with MF. Molecular studies showed that all patients were homozygous for the Thr224Asn mutation in the VPS 45 gene. HSCT was carried out in three patients and was successful in two. VPS 45-associated MF is a novel primary immune deficiency that can be successfully corrected by HSCT if applied early in the course of disease using appropriate conditioning. The diagnosis of VPS 45-associated PMF should be considered in all children presenting with SCN with subsequent development of pancytopenia. Long-term follow-up of these patients is necessary to identify extra-hematological manifestations of VPS45 deficiency.

Allogeneic hematopoietic stem cell transplantation for infants with idiopathic myelofibrosis

IMF is a rare disease in children that can present during infancy and has a protracted course. The only known curative approach for this disease in adult patients is allogeneic HSCT. There are very few reports describing the long-term outcome of young children following stem cell transplantation for IMF. We report on eight patients less than two yr of age with IMF that did not resolve with supportive care measures. All patients underwent myeloablative conditioning regimen with busulfan and cyclophosphamide ± ATG followed by HSCT from matched related (n = 6) or unrelated donor (n = 2). All patients achieved neutrophil and platelet engraftment. Four patients had grade II-III acute GVHD, and chronic GVHD developed in five patients (three mild and two severe). At a median follow-up of eight and a half yr (0.7-9), all patients are alive with complete resolution of their hematologic manifestations. At the last follow-up, all patients had normal endocrine function except for one patient who developed hypothyroidism. To date, this is the largest cohort of young children with IMF treated successfully with HSCT, with the longest duration of follow-up. In conclusion, our study showed that HSCT is a curative option for infants with IMF.

Pulmonary hypertension after hematopoietic stem cell transplantation

Pulmonary hypertension (PH) is a potentially fatal complication of hematopoietic stem cell transplantation (HSCT). Given its nonspecific clinical presentation, it is likely that this clinical entity is underdiagnosed after HSCT. Data describing the incidence, risk factors, and etiology of PH in HSCT recipients are minimal. Physicians caring for HSCT recipients should be aware of this severe post-transplant complication because timely diagnosis and treatment may allow improved clinical outcomes. We summarize the pathophysiology, clinical presentation, diagnosis, and management of PH in HSCT recipients.

Stem cell transplantation in primary myelofibrosis of childhood

Fewer than 40 cases of primary myelofibrosis have been reported in children; hematopoietic stem cell transplantation is the only available curative therapy for this disease. Here, we describe the case of a female infant diagnosed with primary myelofibrosis at the age of 6 months; she underwent successful matched unrelated bone marrow transplantation with complete resolution of disease. We discuss some unique characteristics of primary myelofibrosis in children and review outcome data for children with this disease.

Increased tricuspid regurgitant jet velocity by Doppler echocardiography in adult survivors of childhood cancer: a report from the St Jude Lifetime Cohort Study

PURPOSE

To determine the prevalence of pulmonary hypertension, a late effect of cancer therapy not previously identified in aging survivors of childhood cancer, and associations with chest-directed radiation therapy (RT) and measures of current cardiac function, lung function, and exercise capacity.

PATIENTS AND METHODS

Cross-sectional evaluation of 498 survivors at a median age of 38.0 years (range, 20.0 to 59.0 years) and a median of 27.3 years (range, 12.2 to 46.0 years) from primary cancer diagnosis was performed. Abnormal tricuspid regurgitant jet velocity (TRV) was defined as more than 2.8 m/s by Doppler echocardiography.

RESULTS

Increased TRV was identified in 25.2% of survivors who received chest-directed RT and 30.8% of those who received more than 30 Gy. In multivariable models, increased TRV was associated with increasing dose of RT (1 to 19.9 Gy: odds ratio [OR], 2.09; 95% CI, 0.63 to 6.96; 20 to 29.9 Gy: OR, 3.46; 95% CI, 1.59 to 7.54; ≥ 30 Gy: OR, 4.54; 95% CI, 1.77 to 11.64 compared with no RT; P for trend < .001), body mass index more than 40 kg/m(2) (OR, 3.89; 95% CI, 1.46 to 10.39), and aortic valve regurgitation (OR, 5.85; 95% CI, 2.05 to 16.74). Survivors with a TRV more than 2.8 m/s had increased odds (OR, 5.20; 95% CI, 2.5 to 11.0) of severe functional limitation on a 6-minute walk compared with survivors with a TRV ≤ 2.8 m/s.

CONCLUSION

A substantial number of adult survivors of childhood cancer who received chest-directed RT have an increased TRV and may have pulmonary hypertension as a result of both direct lung injury and cardiac dysfunction. Longitudinal follow-up and confirmation by cardiac catheterization are warranted.

Pulmonary arterial hypertension in pediatric patients with hematopoietic stem cell transplant-associated thrombotic microangiopathy

Pulmonary arterial hypertension (PAH) is rarely included in the differential diagnosis of cardiorespiratory failure after pediatric hematopoietic stem cell transplant (HSCT) as the clinical presentation is nonspecific and may mimic other etiologies. The pathogenesis of PAH in HSCT is poorly understood and the diagnosis requires a high degree of suspicion. We describe 5 children diagnosed with PAH after allogeneic HSCT. All 5 patients had prolonged clinical signs of transplantation-associated thrombotic microangiopathy (TA-TMA) when they presented with hypoxemic respiratory failure and evidence of PAH. Four of the 5 patients had echocardiographic evidence of PAH, and 1 patient was diagnosed with PAH only on autopsy. PAH was diagnosed a median of 76 days (range, 56-101 days) after a diagnosis of TA-TMA. Despite aggressive medical management, including inhaled nitric oxide, 4 of the 5 patients died. One patient recovered from PAH after 11 months of sildenafil therapy. Three of the 4 deceased patients had an autopsy performed, demonstrating severe pulmonary vascular disease consistent with TA-TMA and severe PAH. We conclude that TA-TMA can be associated with significant pulmonary vascular injury presenting as hypoxemic respiratory failure with PAH after HSCT. Pediatric patients with unexplained hypoxemia after HSCT should be evaluated for both transplantation complications, TA-TMA and PAH, accordingly.

Allogeneic cord hematopoietic stem cell transplantation in an infant with primary myelofibrosis

Primary myelofibrosis (PMF) is rare in children. An allogeneic hematopoietic stem cell transplantation (HSCT) is the only known curative therapy for severe cases. Here, we report the case of a female infant with PMF treated with allogeneic HSCT using an unrelated cord blood unit. She had successful reversal of her disease, but experienced complications related to transplant. This is the seventh reported case of HSCT for PMF in children, and the second using umbilical cord blood. We conclude that cord HSCT is a useful curative treatment option in children with PMF, but that efforts must be taken to reduce complications.

An official American Thoracic Society research statement: noninfectious lung injury after hematopoietic stem cell transplantation: idiopathic pneumonia syndrome

RATIONALE

Acute lung dysfunction of noninfectious etiology, known as idiopathic pneumonia syndrome (IPS), is a severe complication following hematopoietic stem cell transplantation (HSCT). Several mouse models have been recently developed to determine the underlying causes of IPS. A cohesive interpretation of experimental data and their relationship to the findings of clinical research studies in humans is needed to better understand the basis for current and future clinical trials for the prevention/treatment of IPS.

OBJECTIVES

Our goal was to perform a comprehensive review of the preclinical (i.e., murine models) and clinical research on IPS.

METHODS

An ATS committee performed PubMed and OVID searches for published, peer-reviewed articles using the keywords "idiopathic pneumonia syndrome" or "lung injury" or "pulmonary complications" AND "bone marrow transplant" or "hematopoietic stem cell transplant." No specific inclusion or exclusion criteria were determined a priori for this review.

MEASUREMENTS AND MAIN RESULTS

Experimental models that reproduce the various patterns of lung injury observed after HSCT have identified that both soluble and cellular inflammatory mediators contribute to the inflammation engendered during the development of IPS. To date, 10 preclinical murine models of the IPS spectrum have been established using various donor and host strain combinations used to study graft-versus-host disease (GVHD). This, as well as the demonstrated T cell dependency of IPS development in these models, supports the concept that the lung is a target of immune-mediated attack after HSCT. The most developed therapeutic strategy for IPS involves blocking TNF signaling with etanercept, which is currently being evaluated in clinical trials.

CONCLUSIONS

IPS remains a frequently fatal complication that limits the broader use of allogeneic HSCT as a successful treatment modality. Faced with the clinical syndrome of IPS, one can categorize the disease entity with the appropriate tools, although cases of unclassifiable IPS will remain. Significant research efforts have resulted in a paradigm shift away from identifying noninfectious lung injury after HSCT solely as an idiopathic clinical syndrome and toward understanding IPS as a process involving aspects of both the adaptive and the innate immune response. Importantly, new laboratory insights are currently being translated to the clinic and will likely prove important to the development of future strategies to prevent or treat this serious disorder.

Unrelated stem cell transplant for infantile idiopathic myelofibrosis

Idiopathic myelofibrosis (IMF) is a rare disease in children that can present during infancy and have a protracted course. The only known curative approach for this disease in adult patients is allogeneic stem cell transplant. We present two cases of IMF during infancy that did not resolve with supportive care measures. Both patients underwent unrelated stem cell transplant with complete resolution of their hematologic manifestations and resolution of the bone marrow fibrosis.

Pulmonary dysfunction in pediatric hematopoietic stem cell transplant patients: non-infectious and long-term complications

Pulmonary complications are among the most frequently encountered sequelae of pediatric hematopoietic stem cell transplantation (HSCT). Non-infectious complications are becoming increasingly more common in this unique population. This review addresses the diagnosis and management of non-infectious manifestations of lung disease in pediatric HSCT patients and briefly discusses the long-term pulmonary function of childhood HSCT survivors.

Pulmonary Arterial Hypertension after Childhood Cancer Therapy and Bone Marrow Transplantation

According to the Third World Symposium on Pulmonary Arterial Hypertension (PAH), chemotherapy is considered to be one of the possible risk factors for patients developing PAH. However, to date, no literature has sufficiently addressed the risk, natural history, and effective treatment of this condition. We report our experience on how early diagnosis, detailed monitoring of disease course, and appropriate treatment application have led to a successful outcome of PAH management in childhood after cancer therapy. Our report reaffirmed the fact that PAH is now a recognized complication of chemotherapy and bone marrow transplantation for leukemia. Combined pulmonary vasodilator treatment has a beneficial effect in improving the patient's condition and functional status as suggested by initial acute pulmonary vasodilator testing.

Chronic lung disease after hematopoietic stem cell transplantation

Tens of thousands of patients undergo hematopoietic stem cell transplantation (HSCT) each year, mainly for hematologic disorders. In addition to the underlying diseases, the chemotherapy and radiation therapy that HSCT recipients receive can result in damage to multiple organ systems. Pulmonary complications develop in 30% to 60% of HSCT recipients. With the widespread use of prophylaxis for certain infections, the spectrum of pulmonary complications after HSCT has shifted from more infectious to noninfectious complications. This article reviews some of the noninfectious, chronic pulmonary complications.