Diagnostic techniques and therapeutic challenges in patients with TP53 dysfunctional chronic lymphocytic leukemia

Trisomy 12 assessment by conventional fluorescence in-situ hybridization (FISH), FISH in suspension (FISH-IS) and laser scanning cytometry (LSC) in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) has an extremely heterogeneous clinical course, and prognostication is based on common genetic abnormalities which are detected by standard cytogenetic methods. However, current methods are restricted by the low number of cells able to be analyzed, resulting in the potential to miss clinically relevant sub-clonal populations of cells. A novel high throughput methodology called fluorescence in situ hybridization in suspension (FISH-IS) incorporates a flow cytometry-based imaging approach with automated analysis of thousands of cells. Here we have demonstrated that the FISH-IS technique is applicable to aneuploidy detection in CLL samples for a range of chromosomes using appropriate centromere probes. This method is able to accurately differentiate between monosomy, disomy and trisomy with a sensitivity of 1% in CLL. An analysis comparing conventional FISH, FISH-IS and laser scanning cytometry (LSC) is presented.

IL-17 induces radiation resistance of B lymphoma cells by suppressing p53 expression and thereby inhibiting irradiation-triggered apoptosis

p53 is a well-known tumor suppressor. However, the regulatory mechanism(s) for p53 expression in B lymphoma cells, and the possible role of p53 in the development of the radioresistance in tumor cells are largely unknown. A human B lymphoma cell line, Karpas1106 (k1106), was used as a model of radioresistance. Apoptosis of k1106 cells was determined using flow cytometry. Expression of p53 was assessed using real time RT-PCR and western blotting. The results showed that irradiation at 8 Gy induced apoptosis in up to 40% of k1106 cells. At the same time, the irradiation markedly increased IL-6 production of the k1106 cells. When k1106 cells were cocultured with regulatory T cells (Tregs) and irradiated, the rate of apoptotic k1106 cells was significantly reduced, indicating an acquired resistance to irradiation. IL-6 derived from the irradiation-treated k1106 cells induced IL-17 expression in Tregs. The IL-17(+)Foxp3(+) T cells suppressed p53 expression in k1106 cells. Collectively, irradiated k1106 cells induce the expression of IL-17 in Tregs, which interferes with the expression of p53 protein in k1106 cells and thereby represses irradiation-triggered apoptosis in k1106 cells.

Long-term results of first salvage treatment in CLL patients treated initially with FCR (fludarabine, cyclophosphamide, rituximab)

Although fludarabine, cyclophosphamide, and rituximab (FCR) together are established as a standard first-line treatment of younger patients with chronic lymphocytic leukemia (CLL), there is little information to guide the management of patients with CLL refractory to, or who have relapsed after, receiving frontline FCR treatment. To define optimal salvage strategy and identify patients unsuitable for retreatment with FCR, we examined the survival and treatment outcome of 300 patients enrolled in a phase 2 study of FCR. After a median 142 months of follow-up, 156 patients developed progressive CLL, with a median survival of 51 months after disease progression. The duration of first remission (REM1) was a key determinant of survival after disease progression and first salvage. Patients with a short REM1 (<3 years) had a short survival period, irrespective of salvage therapy received; these patients have high unmet medical needs and are good candidates for investigation of novel therapies. In patients with a long REM1 (≥3 years), salvage treatment with either repeat FCR or lenalidomide-based therapy results in subsequent median survival exceeding 5 years; for these patients, FCR rechallenge represents a reasonable standard of care.