Genomic prediction of relapse in recipients of allogeneic haematopoietic stem cell transplantation.

Allogeneic haematopoietic stem cell transplantation currently represents the primary potentially curative treatment for cancers of the blood and bone marrow. While relapse occurs in approximately 30% of patients, few risk-modifying genetic variants have been identified. The present study evaluates the predictive potential of patient genetics on relapse risk in a genome-wide manner. We studied 151 graft recipients with HLA-matched sibling donors by sequencing the whole-exome, active immunoregulatory regions, and the full MHC region. To assess the predictive capability and contributions of SNPs and INDELs, we employed machine learning and a feature selection approach in a cross-validation framework to discover the most informative variants while controlling against overfitting. Our results show that germline genetic polymorphisms in patients entail a significant contribution to relapse risk, as judged by the predictive performance of the model (AUC = 0.72 [95% CI: 0.63-0.81]). Furthermore, the top contributing variants were predictive in two independent replication cohorts (n = 258 and n = 125) from the same population. The results can help elucidate relapse mechanisms and suggest novel therapeutic targets. A computational genomic model could provide a step toward individualized prognostic risk assessment, particularly when accompanied by other data modalities.

Low incidence of invasive aspergillosis in allogeneic stem cell transplant recipients receiving amphotericin B inhalation prophylaxis.

In this retrospective study we evaluated the impact of amphotericin B (AmB) deoxycholate inhalation prophylaxis on invasive aspergillosis (IA) in 611 allogeneic stem cell transplant (alloSCT) recipients and their tolerance of the inhalations. The inhalations were not used in 1996-2000 (Period I). In 2001-2005 (Period II) all patients with acute graft-versus-host disease treated with high-dose methylprednisolone used the inhalation prophylaxis with a dose of 25 mg daily. No systemic antifungal prophylaxis was routinely used during the study period. IA was detected in 17 (13 proven, 4 probable) out of 257 (6.6%) patients transplanted in Period I and in 9 (6 proven, 3 probable) out of 354 (2.5%) patients transplanted in Period II (P=0.007). The median time to the diagnosis of IA was 95 days and 155 days post transplant in the 2 periods (P=0.225). The mortality of the patients with IA was 94.1% and 66.6% in Period I and Period II. The median duration of AmB inhalation prophylaxis was 84 days. Breakthrough IA was detected in 1 of the 111 (1%) patients during the prophylaxis. No discontinuation of prophylaxis due to side effects was recorded. Overall, with a median follow-up of 3.5 and 4.6 years, 42.4% and 59% of the patients were alive in Period I and Period II, respectively (P=0.001). In conclusion, the incidence of IA fell during the AmB inhalation prophylaxis, and the inhalations were well tolerated. Mortality of patients with IA was high. The overall survival of patients was significantly higher in Period II, indicating the advances made in SCT therapy over the 10-year period.

Factors influencing the performance level of Candida mannan antigen testing in allogeneic stem cell transplant recipients not receiving fluconazole prophylaxis.

In this study, we evaluated the value of the Platelia(®) Candida mannan antigen (Ag) sandwich enzyme-linked immunosorbent assay test in the diagnosis of invasive candidiasis (IC) and the degree of oral colonization by Candida species in 102 allogeneic stem cell transplantation recipients who were not receiving fluconazole prophylaxis. Of the 2071 serum samples, 98 (4.7%) yielded positive and 78 (3.8%) borderline results with a cut-off value of 0.5 ng/mL. One patient had IC. In this patient, 6 out of 9 serum samples were positive, the first one 49 days before Candida albicans candidemia. False-positive results occurred in 92 (4.4%) samples and in 54 (52.9%) patients. Use of valacyclovir and acyclovir was associated with false-positive or borderline results. The median Ag concentration of the true-positive results was significantly higher than the concentration of the false-positive results (1.60 versus 0.62 ng/mL, P<0.001). With higher cut-off values of 0.75 and 1.0 ng/mL, false-positive Ag test results were seen in 17 and 7 patients, respectively. Of the 657 oral samples, a total of 92 (14%) samples in 39 (38.2%) patients turned out to be positive. C. albicans grew in 82 samples (89.1%), other Candida species in 9 (9.8%), and Aspergillus fumigatus in 1 sample (1.1%). In conclusion, despite the lack of fluconazole prophylaxis, the incidence of IC was low (1%). False-positive Ag test results were common with a test cut-off value of 0.5 ng/mL, and a single positive result does not seem to predict IC. Multiple positive results might predict IC, as 6 out of 9 samples were positive in the only patient with IC, the first one 7 weeks before positive blood cultures.

Invasive Aspergillus infections in allo-SCT recipients: environmental sampling, nasal and oral colonization and galactomannan testing.

A study was performed to investigate the air quality of a haematopoietic SCT ward, colonization of the upper airways with Aspergillus spp. and the role of galactomannan (GM) ELISA testing in serum in the diagnosis of invasive aspergillosis (IA). In 102 allo-SCT recipients, two cases of IA (one proven and one probable) were seen. Of 2071 serum samples, 12 were positive, two in a patient with proven IA and 10 in patients without IA. Of the 2059 negative samples, 22 were taken from the patient with probable IA. Of the 245 environmental samples, 20 (8.2%) were positive for filamentous fungi. Aspergillus fumigatus was seen in 14 samples. A total of 657 oral and nasal swabs were taken. Seven nasal samples and one oral sample were positive for Aspergillus species (A. fumigatus 4, A. niger 4) in four patients, one of whom had probable IA. In summary, most environmental samples were negative, colonization of the oral and nasal cavities was rare and IA was diagnosed in only 2% of patients. The GM ELISA test remained negative in one of two patients with IA and does not seem useful in a population of patients with a low incidence of IA.

Clinical characteristics, outcome and the role of viral load in nontransplant patients with Epstein-Barr viraemia.

Epstein-Barr virus (EBV) is important in the development of post-transplant lymphoproliferative disease in allogeneic stem cell and solid organ transplant recipients. We have studied the clinical significance of EBV DNAaemia among nontransplant patients in a tertiary referral hospital. We retrospectively reviewed the medical records for main diagnosis, outcome, immunosuppressive/cytotoxic chemotherapy and other opportunistic infections of the patients who were found positive in quantitative real-time PCR assay for EBV (EBV-qPCR) between the years 2000 and 2007. Allogeneic stem cell and solid organ transplant recipients were excluded, and all patients in nonsurgical adult wards were included. Altogether, 62 patients had at least one plasma sample positive with an EBV-qPCR. Fifteen were immunocompetent, most had primary EBV infection, and the outcome was good. On the other hand, 36 had malignant disease, seven had HIV infection and seven had immunosuppressive conditions of an other aetiology. All but one of the malignancies were of lymphoid origin, and most of these patients had a history of multiple cytotoxic treatments. Immunosuppressed patients had higher viral loads. EBV viraemia is associated with severe immunosuppression and lymphoid malignancies.

Changing landscape of invasive aspergillosis in allogeneic stem cell transplant recipients.

Invasive aspergillosis (IA) is an important infectious complication in allogeneic stem cell transplant (SCT) recipients. Diagnosis of IA has been difficult and often delayed and treatment outcome has been poor, with mortality rates up to 80%. This review summarizes recent developments in this field. There are indications that the incidence of IA may be decreasing due to multiple factors including better understanding of pathogenesis of IA, earlier diagnosis, and various prophylactic and preventive strategies. Recently posaconazole has shown to be effective in reducing the risk of IA in patients treated for graft-versus-host disease (GVHD). Early use of high-resolution thoracic computed tomography assisted with complimentary methods including bronchoalveolar lavage and serum galactomannan determinations are useful in early diagnosis. Our treatment armamentarium against IA has broadened significantly during the last years and there are some indications of improved outcome more recently. On the other hand, increasing use of blood progenitor grafts instead of marrow with higher risk of chronic GVHD, increasing age of SCT recipients, and wide use of donor lymphocyte infusions for treatment of minimal residual disease or relapse may affect to the opposite direction. Despite some promises and improvements, IA will continue to remain a challenge in the upcoming years.

The utility of intensified environmental surveillance for pathogenic moulds in a stem cell transplantation ward during construction work to monitor the efficacy of HEPA filtration.

A 12-week environmental study was performed to ensure that the patient rooms of an SCT ward with high-efficiency particulate air (HEPA) filtration remained uncontaminated by moulds during close-by construction work. The sampling included measuring the ventilation channel pressure, particle count measurements, air sampling, settled dust analysis and fungal cultures from the oral and nasal cavities of the patients. No changes in the air pressure occurred. Median particle counts in patient rooms were 63-420 particles/l. The mean particle count of the outside air was 173,659 particles/l. Patient room air samples were negative for aspergilli in 32 of 33 cases. All samples of the outside air were positive for moulds. Aspergillus fumigatus was isolated at the beginning of excavation works at the construction area and in two of 33 dust samples from patient rooms. All 70 nasal samples were negative. Of 35 mouth samples, one sample was positive for A. niger in a patient with a previously diagnosed aspergillus infection. During a median follow-up of 214 days, no invasive aspergillus infections were diagnosed in the 55 patients treated during the construction period. In conclusion, the HEPA filters seemed to have performed well in preventing an aspergillosis outbreak.

Candidaemia in allogeneic stem cell transplant recipients: low risk without fluconazole prophylaxis.

Invasive fungal infections (IFI) are common in allogeneic SCT recipients. We have reviewed our experience of IFI with special reference to candidaemia in 685 adult patients transplanted in 1983-2002. The donor was a matched sibling in 505 patients and an unrelated donor in 180 patients. A BM graft was used in 561 patients and a PB graft in 124 patients. Fluconazole prophylaxis was not used during the study period. Definite or probable IFI was observed in 60 patients (8.7%) with a dominance of Aspergillus infections (46 patients, incidence 6.7%). Candidaemia was found only in nine patients (1.3%). The causative agents were Candida albicans (n=8), C. krusei (n=2), and C. glabrata (n=1); in two patients, two causative agents were found. The median time to the diagnosis of candidaemia was 53 days (range 6-249 days) post transplant. Seven patients were neutropaenic at diagnosis, and four patients had experienced acute GVHD. All patients received antifungal therapy, but only one patient was cured. According to this study, candidaemia was a rare event in allogeneic SCT recipients. Thus, systematic prophylaxis against Candida infections might not be indicated. The prognosis of established infections is still poor due to comorbid conditions, notably GVHD.