In a previous report we found point mutations in exons 5-8 of the P53 gene in five of 46 patients with acute myeloid leukaemia (AML), with a predominance of mutations in the 10 patients with 17p monosomy. In this report we extended our findings studying such mutations in 66 unselected additional cases of AML, using polymerase chain reaction single strand conformation polymorphism (SSCP) analysis and nucleotide sequencing. Three of the 66 new cases had a point mutation, leading to a change in one encoded amino acid. Thus, eight of the 112 AML studied had P53 mutations in exons 5-8, suggesting that the incidence of P53 mutation is relatively low in AML. A predominance of mutations in exon 8 (5/8) was found. Six of the eight patients with mutations were older than 60 years of age, and all eight cases had a short survival. All seven mutated cases karyotyped showed complex cytogenetic findings, especially monosomy 5 and/or 7, thus questioning the pathogenic importance of P53 mutations in a context of multiple genetic abnormalities. However, five of them also had 17p monosomy, and in the remaining two cases SSCP and sequence analysis also suggested loss of the normal P53 allele. This supported a role for the P53 gene mutations in leukaemogenesis in the relatively small number of AML patients in whom they were found, through loss of tumour suppressive activity of both normal P53 alleles, as reported in solid tumours.

We treated 53 adults (mean age 54 years, range 17-89; 37 females and 16 males) with chronic idiopathic thrombocytopenic purpura (ITP) by azathioprine. All patients had received at least one form of therapy (including splenectomy in 40 patients) and had less than 50 x 10(9)/1 platelets. The duration of ITP before azathioprine was started ranged from 6 to 350 months (median 19). All patients initially received 150 mg/d of azathioprine. This was associated with a short initial course of prednisone (0.3-0.5 mg/kg d) in 10 of them, who were refractory to prednisone alone. 34 (64%) patients responded, including 24 (45%) complete remissions (CR), three (6%) partial remissions (PR) and seven (13%) minor responses (MR). Median time to achieve response was 4 months. 17 of the CR persisted after 7-182 months, 10 of them after discontinuation of azathioprine. Seven patients relapsed after 4-26 months, five of them after azathioprine was stopped or its dose was reduced. PR were short and the median duration of MR was 8 months. Overall, 21 patients (40%) had responses lasting 1 year or more and 17 (32%) lasting 2 years or more. Median duration of treatment was 18 months (range 3-84). Five patients died of bleeding while on treatment. No prognostic factors for response to azathioprine were found. Mild leucopenia was seen in seven patients and a moderate (x3) increase in transaminases in two patients. No opportunistic infections were seen and no malignancy has occurred since the onset of azathioprine. We conclude that azathioprine gives a relatively high incidence of durable responses and very limited side effects in chronic ITP, when splenectomy has failed or is contraindicated. This efficacy, in our experience, is superior to that obtained with other therapeutic approaches. As responses may be delayed, a course of azathioprine of 4 months is required before one can infer a failure to respond. In responding patients, however, the optimum duration of treatment remains to be established.

We looked for mutations of exons 5 to 8 of the P53 gene in 10 patients with acute myeloid leukemia (AML) and 17p monosomy, and 36 patients with AML and no cytogenetic abnormalities of 17p. DNA was analyzed by polymerase chain reaction, single-strand conformation polymorphism analysis, and nucleotide sequencing. Four of the 10 patients with 17p monosomy showed point mutation, single-nucleotide deletion, or insertion in exons 7 or 8. By contrast, only 1 of the 36 patients with AML and no cytogenetic abnormalities of 17p showed a mutation of the P53 gene in exons 5 to 8 (P less than .01). These results suggest that alterations of the P53 gene may have a role in leukemogenesis in some cases of AML. The fact that P53 gene mutations occurred more often in patients with 17p monosomy seems to support the “recessive” model of tumor suppressive activity of the P53 gene rather than the “dominant” model, in which alteration of only one allele is sufficient for the development of malignancy.

We looked for mutations of exons 5 to 8 of the P53 gene in 10 patients with acute myeloid leukemia (AML) and 17p monosomy, and 36 patients with AML and no cytogenetic abnormalities of 17p. DNA was analyzed by polymerase chain reaction, single-strand conformation polymorphism analysis, and nucleotide sequencing. Four of the 10 patients with 17p monosomy showed point mutation, single-nucleotide deletion, or insertion in exons 7 or 8. By contrast, only 1 of the 36 patients with AML and no cytogenetic abnormalities of 17p showed a mutation of the P53 gene in exons 5 to 8 (P less than .01). These results suggest that alterations of the P53 gene may have a role in leukemogenesis in some cases of AML. The fact that P53 gene mutations occurred more often in patients with 17p monosomy seems to support the “recessive” model of tumor suppressive activity of the P53 gene rather than the “dominant” model, in which alteration of only one allele is sufficient for the development of malignancy.