Donor lymphocyte infusions can result in sustained remissions in patients with residual or relapsed lymphoid malignancy following allogeneic haemopoietic stem cell transplantation.

We treated 17 patients with refractory (n = 7) or relapsed lymphoid malignancy (n = 10) following allogeneic HSCT with donor lymphocyte infusions (DLI). Patients with low-grade disease received DLI alone (n = 7) or following radiotherapy (n = 1). Patients with aggressive disease (n = 9) received prior chemotherapy. Nine out of 15 patients receiving DLI from sibling donors responded after one (n = 6), two (n = 2) and three (n = 1) infusions. Both MUD recipients achieved CR after two and three DLI. In all, 10/17 patients achieved CR including 3/4 patients with chronic lymphatic leukaemia (CLL), 4/4 with mantle cell lymphoma (MCL), 3/4 with follicular NHL but 0/5 with aggressive NHL/Richters. The median CD3 cell dose to achieve CR for siblings was 2 x 10(7)/kg. One patient with CLL had a second transplant following DLI-induced aplasia and is in CR at 14 months giving a final CR rate of 64%. Grade II-IV acute GVHD developed in 45% and chronic GVHD in 8/9 evaluable patients. Of the 11 patients finally achieving CR, one patient with MCL relapsed at 18 months post-DLI but all others remain in remission with a median follow-up of 40 months (range 12-64 months). Low-grade NHL and MCL have a high response rate and sustained remissions following DLI. Aggressive disease responds poorly however, despite pre-DLI chemotherapy.

Methylation of the hMLH1 promoter and its association with microsatellite instability in acute myeloid leukemia.

The hMLH1 and hMSH2 genes are involved in the DNA mismatch repair (MMR) pathway. Defects in either of these genes have been associated with genetic instability in a wide variety of malignancies. A molecular mechanism involved in aberrant MMR gene expression is the epigenetic silencing of transcription by promoter methylation. The importance of MMR promoter methylation in leukemia is presently unclear and we have therefore undertaken a detailed analysis of the promoter regions of hMLH1 and hMSH2 using the technique of bisulfite genomic sequencing. DNA from 55 patients with acute myeloid leukemia (AML) including 23 patients with therapy-related AML (t-AML) have been analyzed. Two patients with de novo AML demonstrated extensive methylation throughout the whole hMLH1 region sequenced, one of whom had previously shown widespread genetic instability, measured as microsatellite instability (MSI). However methylation of hMLH1 was not found in t-AML which has previously been associated with MSI. In addition, methylation was seen at a restricted region of the hMLH1 promoter in both AML patients and healthy controls. The significance of this methylated region of the hMLH1 promoter is uncertain, however, our results confirm that in some patients with AML extensive methylation of hMLH1, but not of hMSH2 may occur, and as is the case in solid tumors this can be associated with the presence of a defective DNA mismatch repair pathway resulting in MSI.

High-dose melphalan followed by radical radiotherapy for the treatment of massive plasmacytoma of the chest wall.

We report three cases of massive chest wall plasmacytoma, each greater than 10 cm in diameter, without evidence of overt myeloma, whom we treated with a combination of VAD chemotherapy consolidated by high-dose melphalan and autologous peripheral blood stem cell transplantation and radical radiotherapy. All three patients completed all components of their therapy without experiencing any major side effects and one patient has had a durable remission. The other two patients have had disease progression but at sites other than the original tumour.

Low dose erythropoietin is effective in reducing transfusion requirements following allogeneic HSCT.

Blood transfusions are frequently required for several weeks after allogeneic transplantation due to inadequate erythropoiesis and defective erythropoietin production. Because red cell transfusion is not without complications in this setting, we sought to avoid them using recombinant human erythropoietin (rhEpo) therapy. We treated 53 patients following allogeneic transplantation for haematological malignancy, using rhEpo at a dose of 10 000 units subcutaneously twice weekly. The median time of commencement of rhEpo was 61 days post-transplant (range 19-465 days), and the median haemoglobin (Hb) concentration was 9.4 g dL(-1) (range 7.0-10.7 g dL(-1)). Thirty patients responded to rhEpo and required no further transfusion with a median rise in Hb after 2 weeks of therapy of 1.5 g (0.7-4.1 g dL(-1)). Erythropoietin (Epo) was discontinued at a median of 5 weeks (range 2-36), when the median Hb concentration was 12.3 g dL(-1) (range 10.0-14.3 g dL(-1)). Those patients who failed to respond to rhEpo frequently had additional reasons for anaemia including cytomegalovirus (CMV) reactivation and treatment, major ABO incompatibility, disease relapse, graft rejection or other transplant-related complications. We conclude that a short course of rhEpo is an effective treatment for anaemia arising following allogeneic hematopoietic cell transplantation, and can avoid the need for transfusion in this setting.

Microsatellite instability and p53 mutations are associated with abnormal expression of the MSH2 gene in adult acute leukemia.

Microsatellite instability (MSI) and p53 mutations have been reported to occur in a significant proportion of patients with therapy-related acute myeloid leukemia (AML). MSH2 is one of the genes involved in DNA mismatch repair to maintain fidelity of genomic replication, and defects of MSH2 are directly involved in MSI in hereditary nonpolyposis colorectal tumors and other human tumors. We have examined the expression of MSH2 protein by Western blotting in 43 adult leukemia samples, including 42 AML and 1 acute lymphoblastic leukemia (ALL) using the antibody MSH2 (Ab-1) (Calbiochem, La Jolla, CA). Abnormal expression of MSH2 protein was found in 14 of 43 (32.6%) cases; a control antibody to actin was always positive. Of the 14 patients that had abnormal expression of MSH2, 2 had therapy-related acute leukemia and 9 were elderly patients (>60 years of age). Expression of MSH2 mRNA was further examined by reverse transcriptase-polymerase chain reaction (RT-PCR). Deletion of MSH2 mRNA was found in 1 of 14 cases with deficient MSH2 protein expression. This group of patients was also screened for loss of heterozygosity (LOH) at the MSH2 locus using a panel 4 microsatellite markers (D2S367, D2S288, D2S391, and D2S2294). LOH was found in 5 of 11 cases examined. There was no evidence of LOH in 14 patients with normal MSH2 expression who were examined using the same markers. Functional evidence for defective DNA mismatch repair in leukemic cells lacking MSH2 as manifest by MSI was found in 7 of 11 cases studied. Mutations of the p53 gene in these 43 samples were also investigated by direct sequencing of full-length p53 cDNA. Mutations of p53 were found in 6 of 43 cases, including 5 of the 14 (35.7%) cases that did not express MSH2 protein. In contrast, mutation of p53 was only found in 1 of 29 (3.4%) cases with normal MSH2 protein expression (chi2 = 5.720, P <.02). These results suggest that abnormalities of DNA mismatch repair due to defective MSH2 expression could play a key role in leukemogenesis, in particular in AML arising in elderly patients or secondary to previous chemotherapy.

DNA repair mechanisms and acute myeloblastic leukemia.

DNA repair mechanisms play a vital role in maintaining genomic integrity. With the wealth of knowledge gained recently on these processes it is becoming clear that defects in repair proteins and proteins associated with the regulation of repair are connected to many different human diseases including cancer. This paper has aimed to review the four major DNA repair processes and in particular concentrate on their association with acute myeloblastic leukemia (AML).

Microsatellite instability occurs in defined subsets of patients with acute myeloblastic leukaemia.

Using a sensitive fluorescent-polymerase chain reaction technique we looked for microsatellite instability (MSI) as functional evidence of mismatch repair defects in 71 cases of acute myeloblastic leukaemia (AML). MSI was assessed at 11 loci in matched leukaemic and constitutional DNA. Nine out of 71 patients (13%) were found to have MSI. Four of these patients had therapy-related leukaemia and the remaining five were all over the age of 60 years. There was a high incidence of adverse-risk cytogenetics in the patients with MSI, including abnormalities of chromosomes 5 and/or 7. Of the nine cases of t-AML included in this study, four (44%) had MSI. MSI was also seen in five of 51 cases (10%) over the age of 60 years but not in any cases under the age of 60 years with de novo AML. Using a sensitive assay, our results suggest that MSI occurs in two subgroups of patients with AML: those with t-AML and the elderly (> 60 years), but is rare in younger patients.

New histological observations in spontaneously developing osteoarthritis in the STR/ORT mouse questioning its acceptability as a model of human osteoarthritis.

Naturally developing spontaneous osteoarthritis (OA) is seen in a number of small animals one of which is the STR/ORT mouse, an accepted model of human OA. A histological evaluation of the patello-femoral joints of 37 male STR/ORT mice has shown features that are inconsistent with the disease in human joints. These include the presence of a prominent acute and chronic synovial inflammatory infiltrate. Such findings call into question the proposed aetiology of the arthropathy in this strain of mouse and its acceptability as a model of human primary OA.