Additional chromosome abnormalities, BCR-ABL tyrosine kinase domain mutations and clinical outcome in Hungarian tyrosine kinase inhibitor-resistant chronic myelogenous leukemia patients

BACKGROUND

Additional chromosome abnormalities (ACAs), mutations of the BCR-ABL tyrosine kinase domain (TKD) and BCR-ABL splice variants may cause resistance to first- and second-generation tyrosine kinase inhibitors (TKIs) in chronic myelogenous leukemia (CML) and Philadelphia-positive (Ph+) acute lymphoid leukemia (ALL).

METHODS

Karyotyping and BCR-ABL TKD mutation screening were performed in 71 imatinib-resistant CML patients and 6 Ph+ ALL patients. A total of 56 out of these 77 patients received second-generation TKI.

RESULTS

ACAs were present in 30 of 65 imatinib-resistant patients (46%). In 27 of 74 imatinib-resistant patients (36%), 15 different BCR-ABL TKD mutations were detected. Mutations were found in 25% of chronic-phase patients (12/47), 33% of accelerated-phase patients (5/15), 71% of blast crisis CML patients (5/7) and 100% of ALL patients. In nilotinib-resistant patients, Y253H, T315I and F359I/V mutations were detected; in dasatinib-resistant patients, L248M, E279K and T315I mutations were detected. T315I was found more frequently in patients on dasatinib than on imatinib therapy. The presence of ACAs predicted shorter survival during first- and second-generation TKI therapy, while TKD mutations only influenced survival during second-generation TKI therapy.

CONCLUSION

For patients with TKI resistance, mutation and ACA screening may play a role in identifying patients with poorer prognosis.

Invasive fungal disease in allogeneic hematopoietic stem cell transplant recipients: an autopsy-driven survey

Invasive mycoses are pre-eminent causes of morbidity and mortality in the allogeneic stem cell transplant setting. In spite of novel diagnostic modalities, the timely and specific identification of invasive mycoses still remains challenging. We analyzed the case history of 97 consecutive patients receiving 103 allogeneic stem cell transplants between January 2003 and October 2006 performed by a single team at 2 transplant centers in Budapest, Hungary. All patients with febrile neutropenia not responding to broad-spectrum antibacterial therapy received amphotericin B deoxycholate empirically. In cases of proven or probable invasive aspergillosis, intravenous voriconazole was instituted. Patients who failed to improve on initial therapy were treated with an antifungal combination, while responders were switched to oral voriconazole. A total of 38 patients died following allografting. Both centers had an autopsy rate of 100% due to central health care regulations. An infectious cause of death could be identified in 15 cases, invasive fungal disease being the most prevalent and accounting for 10 fatalities. Six patients died of invasive aspergillosis, while invasive candidiasis and mucormycosis led to a fatal outcome in 2 cases each. Despite the regular use of galactomannan antigen detections and imaging, an ante mortem diagnosis of proven/probable invasive fungal disease could only be established in 4 of 10 autopsy-verified cases (aspergillosis: 3, candidiasis: 1, mucormycosis: 0). In the remaining 6 patients, deep mycoses were missed clinically and were revealed only by postmortem histology. Present diagnostic and therapeutic strategies still seem to be suboptimal for the management of invasive fungal diseases in the high-risk allogeneic stem cell transplant population.

Successful combined antifungal salvage therapy with liposomal amphothericin B and caspofungin for invasive Aspergillus flavus infection in a child following allogeneic bone marrow transplantation

The emergence of new antifungal compounds with alternative mechanisms of action and improved tolerability has opened up new therapeutic possibilities for the use of combined antifungal treatment in life-threatening systemic fungal infections. A case report of an 8-year-old allogeneic stem cell transplant recipient who developed a central venous catheter tunnel infection caused by Aspergillus flavus is presented here. In spite of conventional and subsequent liposomal amphotericin B therapy the infection progressed rapidly and the necrosis extended further to the thoracic wall, pleura and the right lung. Combined treatment consisting of liposomal amphotericin B and caspofungin was instituted. After 30 days of dual therapy the deep fungal infection resolved and the extensive soft tissue defect showed scarring. One year post-transplant, the patient is well, with normal bone marrow function and full donor chimerism. Although there is limited clinical data on the effectiveness of echinocandins in pediatric patients with documented invasive fungal infections, this case report shows that combining liposomal amphotericin B with caspofungin could be advantageous.

Remarkably reduced transplant-related complications by dibromomannitol non-myeloablative conditioning before allogeneic bone marrow transplantation in chronic myeloid leukemia

A non-myeloablative conditioning protocol containing dibromomannitol (DBM/cytosine arabinoside/cyclophosphamide) has been applied to 36 chronic myeloid leukemia (CML) patients followed by bone marrow transplantation (BMT) from sibling donors. Risk factors include: accelerated phase (10 patients), older age (17 patients over >40 years) and long interval between diagnosis and BMT (27 months on average). Severe mucositis did not occur. Venoocclusive liver disease was absent. Infectious complications were rare. Although grade II-IV acute graft-versus-host disease (GVHD) was present in 9 (25%) cases, there were only 2 serious (III-IV) ones. Chronic GVHD occurred in 25 (69%) cases, preceded by acute GVHD in 9 of the 25 affected patients. Early hematological relapse, 7-29 weeks after BMT, developed in 6 patients (17.6%). No relapse was noted in the completely chimeric patients, however molecular genetic residual disease was observed in 6 patients, in most of them after transient short-term mixed chimeric state. Overall actual survival rate is 83.3% for the 36 cases, and leukemia-free survival is 72.2% for the 34 engrafted patients.

Immunological importance of chimerism in transplantation: new conditioning protocol in BMT and the development of chimeric state

Chimerism is an exceptional immunogenetic state, characterized by the survival and collaboration of cell populations originated from two different individuals. The prerequisits to induce chimerism are immuno-suppression, myeloablation, or severe immunodeficiency of the recipients on the one side and donor originated immuno-hematopoietic cells in the graft on the other. The pathologic or special immunogenetic conditions to establish chimerism are combined with bone marrow transplantation, transfusion, and various kinds of solid organ grafting. Different types of chimerism are known including complete, mixed and mosaic, or split chimerism. There are various methods used to detect the type of chimera state, depending on the immunogenetic differences between the donor and recipient. The induction of complete or mixed chimerism is first determinated by the effect of myeloablative therapy. The chimera state seems to be one of the leading factors to influence the course of the post-transplant period, the frequency and severity of GVHD, and the rate of relapse. However, the most important contribution of the chimeric state is in development of graft versus leukemia effect. A new conditioning protocol (DBM/Ara-C/Cy) for allogeneic BMT in CML patients and its consequence on chimera state and GVL effect is demonstrated.

Responses to single-dose thrombopoietin decrease with higher platelet counts in mice

Since the description of human thrombopoietin (TPO) we investigated the thrombocytosis-inducing capacity of human serum samples derived from individuals with altered thrombocytopoiesis. Several times the degree of thrombocytosis developing in recipient mice differed markedly even when applying the same human material. In the last 2 years, we applied single doses of recombinant human TPO (rHuTPO) to random-bred CFLP mice, and the same observation was made. Taken together with previous information (before 1970) it was possible to select cases in which the percent increases in circulating platelet counts inversely correlated with the starting levels. It appears, however, that apart from the known absorbing role of platelets and megakaryocytes, the response to single doses of exogenous rHuTPO in mice depends, at least partially, on an unknown endogenous homeostatic mechanism. Mixing thrombopoietically active human sera with platelet-free normal serum in a 1:1 ratio remarkably reduced the thrombocytosis-inducing capacity. Repeated pharmacological doses of TPO, applied in the majority of the reported trials, however, easily obscure the physiological control mechanism.

[Use of studies on genome polymorphism in follow up after allogenic bone marrow transplantation]

The study of structures polymorphic in size found in the human genom (the VNTR loci) enables us to differentiate two individuals or--after bone marrow transplantation--to detect the simultaneous presence of two genoms in patients' blood or marrow. The existence of mixed chimerism may influence the therapy. The authors have screened 54 patients, transplanted in their Institute, and their donors by determination of four polymorphic loci. Informative marker was found in 43 cases. The bone marrow transplantation immunotherapy of 29 patients could be followed over 2-36 months. To increase the sensitivity of the polymerase chain reaction method used, the authors introduced the blotting/hybridization steps using isotop labeled repetitive sequences. The results are presented in comparison with literature data.

[A new radiation-free conditioning in bone marrow transplantation and dibromo-mannitol therapy in chronic myeloid leukemia]

A new, radiation-free, conditioning protocol, containing the original Hungarian mitobronitol (DBM) (DBM/ cytosine arabinoside/cyclosphosphamide) has been applied to 36 chronic myeloid leukemia (CML) patients followed by bone marrow transplantation (BMT) from HLA identical sibling donors between 1990-1997. In spite of some prognostically disadvantageous factors (half of them were above 40 years, 10 out of 36 patients were in accelerated phase, the disease history was longer than 2 years in average) the overall survival (30/36) and the leukemia free survival rate (26/36) were in accordance with the best international results. Transplantation-related toxicity was remarkably reduced in comparison to bone marrow transplantation performed by total body irradiation/cyclophosphamide (TBI/Cy) or busulphan/cyclophosphamide (Bu/Cy) conditioning protocols. Acute graft versus host disease was present in lower percentage (9/36) and the number of serious cases was only 2/36. Chronic GVH disease, generally known to be associated with antileukemic effect (GVL), occurred in 25 of cases. Early haematological relapse among the 34 patients with functioning graft occurred in 6 patients which rate is slightly higher than reported after TBI/Cy or Bu/Cy conditioning treatment. There was no relapse among patients transplanted within one year post-diagnosis and patients having CML with accelerated phase. The leukemia free post-transplant period was in association with the chronic GVH disease and full chimeric state.

Immunophenotypic and functional characteristics of haemopoietic cells from human cord blood

Cord blood (CB) as a new source for bone marrow transplantation represents advantageous features concerning stem cell and leucocyte compartments and function. We attempted to get more information about the phenotypes and function of CB cells by investigating their cell surface markers and also the production of IL-2, IFN-gamma and IL-6 by mitogen and alloantigen stimulation. The CB cells were characterized by a low proportion of CD3+ T cells, CD4+ T subpopulation, activated T cells and CD3+CD16/CD56+ cytotoxic cells, suggesting reduced graft versus host potential. The significant increase of CD19/CD3 double positive cells and decrease of CD19/HLA-DR double positive mature B cells reflect that immature B cells exist in CB. In the functional studies, a 27- and 5-fold reduction was observed in the production of IFN-gamma by CB cells stimulated with PHA and allogeneic cells, respectively. The production of IL-2 in PHA-stimulated CB cells also showed a 50% determination. Decrease in the production of these cytokines by CB cells is supported by the decline of the proportion of CD3+ T cells. However, an increase was observed in the production of IL-6 by CB cells stimulated with allogeneic cells as compared with the controls. These results suggest a difference in the functional activity of the T helper cell subsets between the CB and peripheral blood and/or differences in the functional maturity of T helper cell subsets and B cells in these compartments.

Lymphocyte subset reconstitution after allogeneic bone marrow transplantation using radiation-free conditioning regimen for patients with chronic granulocytic leukemia

Conditioning regimens for BMT are important in determining transplant outcome. A radiation-free protocol containing Mitobronitol (DBM), Cytarabine (Ara-C) and Cyclophosphamide (Cy) was used for conditioning of patients with chronic granulocytic leukemia (CGL). Using this conditioning treatment, fewer transplant related complications, including acute GVHD, VOD and severe infections, were observed. Acute GVHD did not develop, but chronic GVHD, accompanied with graft-versus leukemia, was present in half of the cases. To determine the clinical effect of the DBM/Ara-C/Cy conditioning, the recovery of peripheral blood lymphocytes was examined after allogeneic BMT for patients with CGL in comparison with TBI/Cy conditioning. The lymphocyte subsets of 11 DBM patients were followed and analyzed periodically (30-90 days, 4-12 months and > 13 months) using ten monoclonal antibodies and flow cytometry. Decreased percentage of total T cells as well as CD4+ and CD8+ subpopulations, significantly decreased T cell activation and increased proportion of TCR gamma delta + cells were found to be characteristic in the early post-transplant period in the DBM group. Early recovery and consistently higher percentage of B cells were observed for the whole follow-up period of patients receiving DBM conditioning. A high proportion of NK cells was observed in all transplant recipients. These findings suggest that the characteristic pattern of recovering lymphocytes is associated with the lack of severe transplant-related clinical complications following DBM/Ara-C/Cy conditioning.