Detailed analysis of p53 pathway defects in fludarabine-refractory chronic lymphocytic leukemia (CLL): dissecting the contribution of 17p deletion, TP53 mutation, p53-p21 dysfunction, and miR34a in a prospective clinical trial.

The prognosis of fludarabine (F)-refractory chronic lymphocytic leukemia (CLL) is very poor, and underlying mechanisms are only partly understood. To assess the contribution of p53 abnormalities to F-refractory CLL, we studied TP53 mutations in the CLL2H trial (subcutaneous alemtuzumab; n = 99). We found TP53 mutations in 37% of patients. Twelve of 67 (18%) patients without the 17p deletion showed a TP53 mutation and 50% showed evidence of uniparental disomy. A total of 75% of cases with TP53 mutation (without 17p-) showed clonal evolution/expansion. TP53 mutations had no impact on overall survival (P = .48). CLL with the 17p deletion or TP53 mutation showed very low miR-34a expression. To investigate the mechanisms underlying refractory CLL beyond p53, we studied cases without 17p-/TP53 mutation in detail. In several paired samples before and after F-refractory disease, no change in p21/p53 induction was observed after DNA damage. Although TP53 mutations and 17p deletions are found in a high proportion of F-refractory CLL, more than half of the cases cannot be explained by p53 defects (deletion or mutation), and alternative mechanisms need to be investigated. Alemtuzumab is effective irrespective of genetic high-risk subgroups with TP53 mutations. These clinical trials are registered at www.clinicaltrials.gov as #NCT00274976.

Subcutaneous alemtuzumab in fludarabine-refractory chronic lymphocytic leukemia: clinical results and prognostic marker analyses from the CLL2H study of the German Chronic Lymphocytic Leukemia Study Group.

PURPOSE: The phase II CLL2H trial evaluated safety and efficacy of subcutaneous alemtuzumab in patients with fludarabine-refractory chronic lymphocytic leukemia (CLL). Clinical and biologic markers were evaluated for their impacts on outcome. PATIENTS AND METHODS: One hundred nine patients were enrolled, and 103 received at least one dose of alemtuzumab. After dose escalation, alemtuzumab was administered subcutaneously at 30 mg three times weekly for up to 12 weeks. Response was assessed every 4 weeks during treatment and quarterly thereafter. RESULTS: The overall response rate was 34% (complete response, 4%; partial response, 30%). The median progression-free survival was 7.7 months, and the median overall survival (OS) was 19.1 months. Grades 3 to 4 neutropenia, thrombocytopenia, and anemia occurred in 56%, 57%, and 49% of patients, respectively. Grades 3 to 4 noncytomegalovirus and cytomegalovirus infections occurred in 29% and 8% of patients, respectively. Injection-site skin reactions were generally mild. Efficacy did not vary significantly in subgroups defined by genetic parameters (in particular, in 17p deletion, 11q deletion, mutated TP53, and unmutated VH), but efficacy was inferior in patients with increased beta2-microglobulin (beta2-MG) and thymidine kinase (TK). In multivariate analysis of clinical and biologic variables, age, performance status, beta2-MG, and TK were independent prognostic factors for OS. CONCLUSION: Subcutaneous alemtuzumab appears as effective and safe as intravenous alemtuzumab in fludarabine-refractory CLL. Subcutaneous administration should be the preferred delivery route because of its efficacy, convenience, improved adverse effect profile, and cost savings. In contrast to chemotherapy-based therapy, alemtuzumab treatment overcomes the adverse prognostic impact of VH mutation status, TP53 mutation, and genomic aberrations.

Insertion of FLT3 internal tandem duplication in the tyrosine kinase domain-1 is associated with resistance to chemotherapy and inferior outcome.

To evaluate internal tandem duplication (ITD) insertion sites and length as well as their clinical impact in younger adult patients with FLT3-ITD-positive acute myeloid leukemia (AML), sequencing after DNA-based amplification was performed in diagnostic samples from 241 FLT3-ITD-mutated patients. All patients were treated on 3 German-Austrian AML Study Group protocols. Thirty-four of the 241 patients had more than 1 ITD, leading to a total of 282 ITDs; the median ITD length was 48 nucleotides (range, 15-180 nucleotides). ITD integration sites were categorized according to functional regions of the FLT3 receptor: juxtamembrane domain (JMD), n = 148; JMD hinge region, n = 48; beta1-sheet of the tyrosine kinase domain-1 (TKD1), n = 73; remaining TKD1 region, n = 13. ITD length was strongly correlated with functional regions (P < .001). In multivariable analyses, ITD integration site in the beta1-sheet was identified as an unfavorable prognostic factor for achievement of a complete remission (odds ratio, 0.22; P = .01), relapse-free survival (hazard ratio, 1.86; P < .001), and overall survival (hazard ratio, 1.59; P = .008). ITD insertion site in the beta1-sheet appears to be an important unfavorable prognostic factor in young adult patients with FLT3-ITD-positive AML. The clinical trials described herein have been registered as follows: AML HD93 (already published in 2003), AML HD98A (NCT00146120; http://www.ClinicalTrials.gov), and AMLSG 07-04 (NCT00151242; http://www.ClinicalTrials.gov).

Gene mutations and response to treatment with all-trans retinoic acid in elderly patients with acute myeloid leukemia. Results from the AMLSG Trial AML HD98B.

BACKGROUND: In a previous randomized trial, AML HD98B, we showed that administration of all-trans retinoic acid in addition to intensive chemotherapy improved the outcome of older patients with acute myeloid leukemia. The objectives of this study were to evaluate the prognostic impact of gene mutations and to identify predictive genetic factors for the all-trans retinoic acid treatment effect. DESIGN AND METHODS: Data from mutation analyses of the NPM1, CEBPA, FLT3, and MLL genes were correlated with outcome in patients 61 years and older treated within the AML HD98B trial. RESULTS: The frequencies of mutations were: NPM1, 23%; CEBPA, 8.5% (analysis restricted to patients with a normal karyotype); FLT3 internal tandem duplications (ITD), 17%; FLT3 tyrosine kinase domain mutations, 5%; and MLL partial tandem duplications, 4.5%. The genotype mutant NPM1 was positively and adverse cytogenetics as well as higher white blood cell count negatively correlated with achievement of complete remission. In Cox regression analysis, a significant interaction between the genotype mutant NPM1 without FLT3-ITD and treatment with all-trans retinoic acid was identified, in that the beneficial effect of all-trans retinoic acid on relapse-free and overall survival was restricted to this subgroup of patients. Other significant factors for survival were age, adverse cytogenetics, and logarithm of white cell count. CONCLUSIONS: In elderly patients with acute myeloid leukemia, NPM1 mutations are associated with achievement of complete remission, and the genotype 'mutant NPM1 without FLT3-ITD' appears to be a predictive marker for response to all-trans retinoic acid given as an adjunct to intensive chemotherapy (ClinicalTrials.gov Identifier: NCT00151242).