Guy S. Lucas

A Gain-of-Function Mutation in the HIF2A Gene in Familial Erythrocytosis

Hypoxia-inducible factor (HIF) alpha, which has three isoforms, is central to the continuous balancing of the supply and demand of oxygen throughout the body. HIF-alpha is a transcription factor that modulates a wide range of processes, including erythropoiesis, angiogenesis, and cellular metabolism. We describe a family with erythrocytosis and a mutation in the HIF2A gene, which encodes the HIF-2alpha protein. Our functional studies indicate that this mutation leads to stabilization of the HIF-2alpha protein and suggest that wild-type HIF-2alpha regulates erythropoietin production in adults.

The rho-kinase inhibitors Y-27632 and fasudil act synergistically with imatinib to inhibit the expansion of ex vivo CD34(+) CML progenitor cells.

Evidence from cell line-based studies indicates that ρ-kinase may play a role in the leukaemic transformation of human cells mediated by the BCR/ABL tyrosine kinase, manifest clinically as chronic myeloid leukaemia (CML). We therefore employed two separate inhibitors, Y-27632 and fasudil, to inhibit the activity of ρ-kinase against ex vivo CD34+ cells collected from patients with CML. We compared the effects of ρ-kinase inhibition in those cells with the effects of direct inhibition of BCR/ABL using the specific inhibitor imatinib. We found that inhibition of ρ-kinase inhibited the effective proliferation, and reduced survival of CML progenitor cells. When combined with imatinib, ρ-kinase inhibition added to the anti-proliferative and pro-apoptotic effects of the BCR/ABL inhibitor. Our studies may indicate therapeutic benefit in some cases for the combination of ρ-kinase inhibitors with imatinib.

Therapy-related acute promyelocytic leukaemia.

We report three patients with acute promyelocytic leukaemia (APL) occurring after treatment for other malignant disorders. One patient had had razoxane (a drug affecting DNA topoisomerase II) for cancer of the colon, and the other two had had treatment for cancer of the breast. Two out of the three patients went into complete remission. We review the published literature on therapy‐related acute promyelocytic leukaemia (t‐APL) and suggest that it is a genuine clinical entity which may be caused by drugs affecting DNA topoisomerase II, and has a prognosis similar to de novo APL.

The effect of Bcr-Abl protein tyrosine kinase on maturation and proliferation of primitive haematopoietic cells.

BackgroundChronic Myeloid Leukaemia (CML) is characterised by the chromosomal translocation resulting in expression of the Bcr-Abl protein tyrosine kinase (PTK) in early stem cells and their progeny. However the precise nature of Bcr-Abl effects in primitive CML stem cells remains a matter of active debate.Materials and MethodsExtremely primitive Bcr-Abl fusion positive cells were purified from patients with CML using multiparameter flow cytometric analysis of CD34, Thy, and lineage marker (Lin) expression, plus rhodamine-123 (Rh-123) brightness. Progenitor cells of increasing maturity were examined for cycling status by flow cytometry and their proliferative status directly correlated with cell phenotype. The activation status of a key transcription factor, signal transducers and activators of transcription (STAT-5), was also analyzed by immunocytochemistry.ResultsThe most primitive stem cells currently defined (CD34+Lin-Thy+ Rh-123lo) were present as a lower proportion of the stem cell compartment (CD34+Lin-) of CML patients at presentation than of normal individuals (2.3% ± 0.4 compared with 5.1% ± 0.6 respectively). Conversely there was a significantly higher proportion of the more mature cells (CD34+Lin-Thy-Rh-123 hi) in CML patients than in normal individuals (79.3 ± 1.8 compared with 70.9 ± 3.3). No primitive subpopulation of CML CD34+Lin-cells was cycling to a significantly greater degree than cells from normal donors, in fact, late progenitor cells (CD34+ Lin+) were cycling significantly less in CML samples than normal samples. STAT5, however, was observed to be activated in CML cells.ConclusionsWe conclude that no subpopulation of CML stem cells displays significantly increased cell cycling. Thus, increased cycling cannot be a direct consequence of Bcr-Abl PTK acquisition in highly enriched stem cells from patients with CML. In vivo CML need not be considered a disease of unbridled stem cell proliferation, but a subtle defect in the balance between self renewal and maturation.

Ribosome-associated nucleophosmin 1: increased expression and shuttling activity distinguishes prognostic subtypes in chronic lymphocytic leukaemia.

Two distinct groups of chronic lymphocytic leukaemia (CLL) are distinguished by the presence or absence of somatic hypermutation of the immunoglobulin heavy‐chain gene. CLL without somatic hypermuataion has an adverse outcome, but the precise biological differences that underlie this more aggressive clinical‐course are unclear. Using a proteomic approach, we found that the two prognostic forms of CLL were consistently distinguished according to their protein expression pattern. The most important difference observed related to the different expression of nucleophosmin 1 between the two forms of CLL. This different expression was not related to apoptosis, proliferation or gene mutation. However, co‐immunoprecipitation experiments identified an association between nucleophosmin 1 and ribosomal proteins. Using immunocytofluorescence, nucleophosmin 1 expression was identified in the nucleoli and nucleoplasm of all cells, but in a proportion of cells, nucleophosmin had been transferred from the nucleoplasm to the cytoplasm. Both the fluorescent intensity, and the frequency of cytoplasmic nucleophosmin 1 expression, was higher in CLL without somatic hypermutation. We propose therefore, that nucleophosmin 1, in association with ribosomal proteins, undergoes nucleo‐cytoplasmic shuttling in CLL. This process is most prominent in un‐mutated CLL and may signify altered protein biosynthesis.

IgA myeloma of donor origin arising 7 years after allogeneic renal transplant

We report the case of a 38‐year‐old man who developed IgA myeloma of donor origin 7 years after allogeneic renal transplant. The diagnosis of multiple myeloma was unequivocal and based on positive results from serum electrophoresis, skeletal survey and bone marrow investigations. The donor origin of the myeloma cells was confirmed by DNA fingerprinting. We believe this is the first reported case of disseminated multiple myeloma of donor origin developing after allogeneic renal transplant and, as such, gives some insight into the natural history and biology of the disease.

Outcomes following 50 mg versus 100 mg alemtuzumab in reduced-intensity conditioning stem cell transplants for acute myeloid leukaemia and poor risk myelodysplasia

Long-term disease-free survival can be achieved in patients with acute myeloid leukaemia (AML) and poor risk myelodysplasia (MDS) using conventional allogeneic stem cell transplantation (SCT). However, the toxicities of myeloablative conditioning regimens limit this procedure to younger patients who are medically fit. Reduced intensity conditioning (RIC) regimens have a lower toxicity and can be used in older patients with or without co-morbidities. Designed to exploit an immunologically mediated graft-versus-leukaemia (GvL) effect as their dominant anti-tumour mechanism, they demonstrate rapid donor engraftment. Graft-versus-host disease (GVHD)-related morbidity and mortality, however, remain problematic in this increasing elderly population (Slavin et al, 1998; Giralt et al, 2001). Within the UK, commonly used RIC regimens combine fludarabine with an alkylating agent, melphalan, or busulphan and include alemtuzumab, a monoclonal antibody with potent anti-T-cell activity. These lead to reliable engraftment with acceptably low GVHD and treatment-related mortality (TRM) (Kottaridis et al, 2000; Chakraverty et al, 2002; Tauro et al, 2005). Relapse, however, remains a major cause of treatment failure. The use of alemtuzumab may compromise the desired GvL effect and thereby contribute to relapse (Tauro et al, 2005). To date, there are no published prospective or retrospective studies evaluating the optimal dose of alemtuzumab. This analysis retrospectively compared outcomes following 50 mg versus 100 mg alemtuzumab in RIC SCT for patients with AML and poor risk MDS and evaluate TRM, over-all survival (OS), event-free survival (EFS), time to relapse and incidence of GVHD. Between 1999 and 2005, 98 patients underwent such a procedure at the following UK centres: Manchester Royal Infirmary, Christie Hospital, Nottingham City Hospital and University Hospital Birmingham. Median age was 55 years (22–71 years). Patient and transplant demographics are summarised in Table I. For comparison, patients were divided into two subgroups according to the dose of alemtuzumab given; 40 patients were given 100 mg alemtuzumab (A100) whilst 58 received 50 mg (A50). Timing of alemtuzumab infusions varied between centres (D-5 to D-1; D-8 to D-4; D-10 to D-6). There were significant differences between the two patient subgroups with respect to median age, conditioning regimens and GVHD prophylaxis. All conditioning regimens were generally well tolerated. High engraftment rates were observed; only one patient in each group failed to engraft. In both cases, this was associated with infusion of a suboptimal stem cell dose (£2 · 10 CD34 per kg; £2 · 10 nucleated cells per kg). Non-relapse TRM was 12Æ5% at 100 days and 17Æ5% at 1 year in patients receiving 100 mg alemtuzumab and 3% and 14% respectively, in those receiving 50 mg (P = 0Æ38). TRM was primarily due to infective causes and higher in those receiving 100 mg alemtuzumab. Over-all survival and EFS of all patients were 71% and 61% at 1 year and appeared to plateau from 3 years at 44%. Survival at 3 years was lower for unrelated when compared

Stage IV adult sporadic Burkitt lymphoma/leukemia with complex bone marrow cytogenetics is associated with a very poor outcome

To the editor: Adult Burkitt lymphoma/leukemia (BLL) is a rare, aggressive B-cell neoplasm with typical morphologic appearances. It is characterized by rapid proliferation of mature B cells (Ki67/MIB-1 staining ≥ 99%) and overexpression of c -Myc, which most commonly results from the

Leukaemia diagnosed as a consequence of haematuria assessment: a case report

IntroductionT-cell prolymphocytic leukaemia is a rare condition that constitutes around 2% of cases of small lymphocytic leukaemia in adults. It follows an aggressive clinical course with a poor prognosis.Case presentationWe report a 55-year-old male who was diagnosed with T-cell prolymphocytic leukaemia following investigations for microscopic haematuria. Splenomegaly was identified on a plain abdominal radiograph and intravenous urography, thus triggering further investigations and diagnosis.ConclusionOur case-report serves to remind us of the need to bear in mind other possible pathologies outwith our own area of expertise when interpreting results of any kind. This is perhaps increasingly important in the current era of increasing sub-specialisation throughout medicine.