Cytogenetic follow-up after bone marrow transplantation for Philadelphia-positive chronic myeloid leukemia

Spurious case of XX maleness in a patient with a history of Wiskott-Aldrich syndrome

OBJECTIVE

To alert endocrinologists about the potential for karyotype confusion in patients who have undergone bone marrow transplantation.

METHODS

Clinical, laboratory, and imaging data are reported on a young adult male patient who initially presented because of concerns about short stature.

RESULTS

An 18-year-old fully virilized male patient with a history of Wiskott-Aldrich syndrome had undergone successful bone marrow transplantation in infancy. The donor was his older sister. Many years later, he underwent evaluation because of short stature and was found to have a 46, XX karyotype. This unexpected finding led to several costly laboratory and imaging studies, as well as a new diagnosis of a disorder of sex development. The patient was referred to our medical center for further evaluation of XX sex reversal. A skin biopsy was eventually performed, which revealed a 46, XY karyotype. This unusual case highlights the fact that a peripheral blood specimen from bone marrow transplant recipients reflects the genetic makeup of the bone marrow donor.

CONCLUSION

Although the cytogenetic changes that occur in recipients of bone marrow transplants are well known to hematologists and oncologists, they are not commonly recognized by other health care providers. Increased awareness of this potential situation in long-term survivors of bone marrow transplantation is needed.

Cytogenetic evolution patterns in CML post-SCT

The cytogenetic evolution patterns in chronic myeloid leukemia (CML) after allogeneic (allo) stem cell transplantation (SCT) are different from the ones observed in non-transplanted patients, a phenomenon suggested to be caused by the conditioning regime. We reviewed 131 CMLs displaying karyotypic evolution after SCT (122 allo, nine autologous (auto)), treated at Lund University Hospital or reported in the literature. Major route abnormalities (i.e., +8, +Ph, i(17q), +19, +21, +17 and -7) were seen in 14%, balanced aberrations in 61%, hyperdiploidy in 19%, pseudodiploidy in 79%, divergent clones in 14%, and Ph-negative clones in 21%. The breakpoints involved in secondary structural rearrangements clustered at 1q21, 1q32, 7q22, 9q34, 11q13, 11q23, 12q24, 13q14, 17q10 and 22q11. Cytogenetic abnormalities common in AML after genotoxic exposure, that is, der(1;7)(q10;p10), del(3p), -5, del(5q), -7, -17, der(17p), -18, and -21, were only rarely seen post-SCT. Comparing the cytogenetic features in relation to type of SCT revealed that balanced aberrations were significantly more common after allo than after auto SCT (64 and 22%, respectively, P=0.03). In addition, there was a trend as regards hyperdiploidy being more common after auto (P=0.07) and pseudodiploidy being more frequent after allo SCT (P=0.09). Possible reasons for these differences are discussed.

Allogeneic bone marrow transplantation (BMT) for adults with acute lymphoblastic leukemia (ALL): predictive role of minimal residual disease monitoring on relapse

We developed a PCR-based method to monitor clonogenic IgH VDJ rearrangement as a possible predictor of relapse in patients with acute B-ALL after allogeneic bone marrow transplantation (BMT). We studied 23 patients at diagnosis, before and after BMT. At the time of BMT, 13 patients were in first complete remission, eight in second complete remission and two in relapse. Four patients were PCR negative before BMT and remained PCR negative also after BMT (-/- pattern). They are still in remission after a median follow-up of 41 months. Nineteen patients were MRD-positive before BMT: three were PCR negative at first determination after BMT (+/- pattern) and maintain remission. Sixteen patients were PCR-positive at first determination after BMT (+/+ pattern): five became PCR negative (+/+/- pattern) (four with chronic graft-versus-host disease (GVHD) and two after donor lymphocyte infusions (DLI)). Nine patients remained PCR-positive (+/+/+ pattern) (four remain in remission, and six relapsed); two patients died before transplant. In conclusion, PCR negative patients before BMT remained negative post-BMT; many pre-BMT positive patients had initial MRD positivity after BMT: 37% of them achieved a molecular remission with cGVHD or DLI.

Cytogenetic and molecular genetic evolution of chronic myeloid leukemia

Chronic myeloid leukemia (CML) is genetically characterized by the presence of the reciprocal translocation t(9;22)(q34;q11), resulting in a BCR/ABL gene fusion on the derivative chromosome 22 called the Philadelphia (Ph) chromosome. In 2-10% of the cases, this chimeric gene is generated by variant rearrangements, involving 9q34, 22q11, and one or several other genomic regions. All chromosomes have been described as participating in these variants, but there is a marked breakpoint clustering to chromosome bands 1p36, 3p21, 5q13, 6p21, 9q22, 11q13, 12p13, 17p13, 17q21, 17q25, 19q13, 21q22, 22q12, and 22q13. Despite their genetically complex nature, available data indicate that variant rearrangements do not confer any specific phenotypic or prognostic impact as compared to CML with a standard Ph chromosome. In most instances, the t(9;22), or a variant thereof, is the sole chromosomal anomaly during the chronic phase (CP) of the disease, whereas additional genetic changes are demonstrable in 60-80% of cases in blast crisis (BC). The secondary chromosomal aberrations are clearly nonrandom, with the most common chromosomal abnormalities being +8 (34% of cases with additional changes), +Ph (30%), i(17q) (20%), +19 (13%), -Y (8% of males), +21 (7%), +17 (5%), and monosomy 7 (5%). We suggest that all these aberrations, occurring in >5% of CML with secondary changes, should be denoted major route abnormalities. Chromosome segments often involved in structural rearrangements include 1q, 3q21, 3q26, 7p, 9p, 11q23, 12p13, 13q11-14, 17p11, 17q10, 21q22, and 22q10. No clear-cut differences as regards type and prevalence of additional aberrations seem to exist between CML with standard t(9;22) and CML with variants, except for slightly lower frequencies of the most common changes in the latter group. The temporal order of the secondary changes varies, but the preferred pathway appears to start with i(17q), followed by +8 and +Ph, and then +19. Molecular genetic abnormalities preceding, or occurring during, BC include overexpression of the BCR/ABL transcript, upregulation of the EVI1 gene, increased telomerase activity, and mutations of the tumor suppressor genes RB1, TP53, and CDKN2A. The cytogenetic evolution patterns vary significantly in relation to treatment given during CP. For example, +8 is more common after busulfan than hydroxyurea therapy, and the secondary changes seen after interferon-alpha treatment or bone marrow transplantation are often unusual, seemingly random, and occasionally transient. Apart from the strong phenotypic impact of addition of acute myeloid leukemia/myelodysplasia-associated translocations and inversions, such as inv(3)(q21q26), t(3;21)(q26;q22), and t(15;17)(q22;q12-21), in CML BC, only a few significant differences between myeloid and lymphoid BC are discerned, with i(17q) and TP53 mutations being more common in myeloid BC and monosomy 7, hypodiploidy, and CDKN2A deletions being more frequent in lymphoid BC. The prognostic significance of the secondary genetic changes is not uniform, although abnormalities involving chromosome 17, e.g., i(17q), have repeatedly been shown to be ominous. However, the clinical impact of additional cytogenetic and molecular genetic aberrations is most likely modified by the treatment modalities used.

Primary vs. secondary neoplasia-associated chromosomal abnormalities--balanced rearrangements vs. genomic imbalances?

Two quite distinct neoplasia-associated karyotypic patterns are emerging. One is characterized by simple and disease-specific abnormalities, and the other is characterized by multiple and nonspecific aberrations. The former pattern is typical of most leukemias and lymphomas and of some mesenchymal tumors, but it is rare in epithelial neoplasms. The latter pattern is found in most epithelial tumor types, in several mesenchymal neoplasms, but in only a few hematologic malignancies. Primary chromosome aberrations, which are believed to be essential in establishing the neoplasm, and secondary changes, which are considered to be important in tumor progression, may be distinguished in the tumors characterized by simple and disease-specific abnormalities. Here, we propose that these aberrations are genetically and hence, most likely, functionally distinct. Primary abnormalities lead to specific gene rearrangements, whereas secondary chromosomal changes result in large-scale genomic imbalances. According to this hypothesis, there are no unbalanced primary aberrations, only secondary imbalances masquerading as primary. This proposition has a number of conceptual ramifications. First, the genetic mechanisms underlying tumor initiation and progression would seem to be totally different. Second, the elucidation of the molecular consequences of the secondary aberrations will be an arduous task, even if one were to adhere to the view that cytogenetically identified genomic imbalances may be reduced to simple gains or losses of single oncogenes or tumor suppressor genes. Third, the cytogenetic diagnosis of neoplasms will have to take into account that an unbalanced "primary" abnormality is secondary to a submicroscopic, truly primary change of major diagnostic and prognostic importance.

Sequential cytogenetic study of patients after bone marrow transplantation

Thirty-one patients (19 males and 12 females; mean age 23.9 years, range 4-41 years) were treated with bone marrow transplantation (BMT) after intensive chemoradiotherapy. Their diagnoses were as follows: chronic myeloid leukemia (CML) in 13, acute myeloid leukemia (AML) in seven, acute lymphocytic leukemia (ALL) in six, myelodysplastic syndrome (MDS) in two, aplastic anemia (AA) in two, and Fanconi anemia (FA) in one. Allogeneic BMT was performed in 28 cases (17 donors were of like sex, 11 were of unlike sex), one patient received syngenic transplant, and one received transplant of cells obtained from an unrelated donor through a computerized international registry in London. Autologous BMT was performed in three patients. BM cells were analyzed cytogenetically at diagnosis, before and serially after BMT (three to nine times). Follow-up ranged from 2 to 55.5 months. Cytogenetic examination was a very useful method for monitoring posttransplantation course in patients with CML or in those who received BM cells of unlike sex. Results of concomitant cytogenetic examinations are reported in detail.

Karyotype evolution of Ph positive chronic myelogenous leukemia patients relapsed in advanced phases of the disease after allogeneic bone marrow transplantation

Sixty-eight patients affected by Philadelphia chromosome (Ph) positive chronic myelogenous leukemia (CML) underwent allogeneic bone marrow transplantation (BMT) and were successfully studied from a cytogenetic point of view, before and after the BMT. Nineteen had evidence of cytogenetic and clinical relapse. Cytogenetic analyses of 14 patients who, after the relapse, showed progression to the accelerated or blastic phase of the disease, are presented. Five of these cases had only the Ph chromosome without karyotype evolution; in one case Ph duplication without other anomalies was detected, while in the remaining eight cases cytogenetic analysis showed apparently random clonal structural abnormalities (translocations, inversions, deletions, and marker formations). Therefore, the classical "non-random" abnormalities (+8, i(17q), +Ph, +19, +21) were not as common as in conventionally treated Ph+ CML. From our data, karyotype evolution during advanced phases in Ph+ CML patients after BMT differs from the evolution seen in conventionally treated patients, by the presence of numerous structural unusual abnormalities, possibly related to radiochemotherapy conditioning to BMT. Therefore, BMT treatment is not always able to eradicate the Ph+ clone but can reduce the incidence of the formation and/or expansion of Ph+ clones with additional non-random abnormalities.

Cytogenetic events after bone marrow transplantation for Philadelphia chromosome positive chronic myeloid leukemia

Allogeneic bone marrow transplantation is the only way to cure patients with Ph1+ chronic myeloid leukemia. It is commonly assumed that, in order to obtain a cure for the patients, the leukemic clone must be completely destroyed by the conditioning treatment and the donor's bone marrow must repopulate the hemopoietic niches leading to a "complete chimera". However, cytogenetic analyses, supported by molecular ones, indicate that Ph1+ cells, far from being completely destroyed by chemo-radiotherapy may persist for a long time, probably in the majority of the patients. As demonstrated by the outcome of patients receiving T-cell depleted marrow, immune mechanisms must be involved in controlling and progressively reducing the size of the residual leukemic clone. Furthermore, immunodulating therapeutic strategies, represented by cyclosporin-A discontinuation or alpha interferon treatment, may successfully reduce the Ph1+ cell population even after a full relapse.

Cytogenetics in the investigation of haematological disorders

Chronic and acute, myeloid and lymphatic haematological neoplasms are characterized by acquired genetic rearrangements that, in the majority of cases, can be detected as clonal chromosomal abnormalities. The aberrations are either primary, meaning that they contribute to the establishment of the neoplasm, or secondary, in which case they are acquired during the clonal evolution and malignization of the neoplastic cells. The abnormalities are non-randomly distributed; the aberration pattern differs from disease to disease and sometimes is so characteristic that individual rearrangements may be virtually pathognomonic for particular neoplasms. The cytogenetic characterization of haematological malignancies is of two-fold importance. First, the recurrent aberrations provide us with an insight into the pathogenetic mechanisms that are operative. They pinpoint those areas of the human genome that carry genes or regulatory sequences whose function is disturbed in leukaemias and lymphomas. Using DNA recombinant techniques in addition to chromosome-level investigations of these cancer-associated rearrangements, the molecular pathology of leukaemias and lymphomas is now gradually being unravelled. Second, even before the long-term goal of a more fundamental understanding of the neoplastic process is reached, the cytogenetic aberrations have a direct clinical importance. The finding of an acquired, clonal chromosome abnormality in haematopoietic cells (-Y in old men is an exception) means that the patient has a neoplastic disease. Often, but by no means always, the type of aberration is also informative as to which type of neoplasm is present. During therapy, remission and relapse can be monitored by cytogenetic analyses. Finally, the karyotypic pattern influences prognosis and may thus be taken into account when the choice of therapy is made.