Ristocetin-induced platelet aggregation for monitoring of bleeding tendency in CLL treated with ibrutinib

Bleeding because of impaired platelet function is a major side effect of the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib. We quantitatively assessed ristocetin-induced platelet aggregation (RIPA) in 64 patients with chronic lymphocytic leukemia (CLL) under ibrutinib at 287 time points. Eighty-seven bleeding episodes in 39 patients were registered (85 Common Toxicity Criteria (CTC) grade 1 or 2, 2 CTC grade 3) during a median observation period of 10.9 months. At times of bleeding, RIPA values were significantly lower (14 vs 28 U; P<0.0001). RIPA was impaired in patients receiving concomitant antiplatelet therapy or anticoagulation (14 vs 25 U, P=0.005). A gradual decline of median RIPA values was observed with increasing bleeding severity. Importantly, no CTC grade 2 or 3 bleeding were observed with RIPA values of >36 U. Sequential monitoring indicated a decrease of RIPA values from a median of 17 to 9 U within 2 weeks after initiation of treatment as well as an increase above the critical threshold of 36 U within 7 days when ibrutinib was paused. Low RIPA values were similar during treatment with another BTK inhibitor, CC292. Quantitative assessment of platelet function is a practical tool to monitor bleeding tendency under BTK-inhibitor therapy.

Gene expression signature of chronic lymphocytic leukaemia with Trisomy 12

BACKGROUND

The prognosis of chronic lymphocytic leukaemia (CLL) patients is largely determined by the karyotype of the malignant clone. We have investigated the gene expression profile associated with trisomy 12 (+12).

DESIGN

Initially, unselected peripheral blood mononuclear cells of four patients with +12 were compared with 16 CLL controls using microarray analysis.

RESULTS

were validated by quantitative real-time PCR with RNA from 61 patients (29 with +12, 32 CLL controls). Results Seven genes showing the strongest correlation with +12 in microarray analysis were selected for real-time PCR: HIP1R, MYF6, SLC2A6, CD9 (overexpressed); CD200, P2RY14, RASGRP3 (underexpressed). Four genes were significantly associated with +12: HIP1R (P<0.0001), MYF6 (P=0.007), P2RY14 (P=0.014), CD200 (P=0.028). Receiver Operating Characteristic curve analysis revealed that HIP1R expression was a highly sensitive and specific marker for +12 in CLL patients. MYF6 was exclusively expressed in normal or malignant B cells in peripheral blood but was poorly predictive for +12. As expected, a number of overexpressed genes are located on chromosome 12 (HIP1R, MYF6). Interestingly, both significantly underexpressed genes (P2RY14, CD200) reside on the long arm of chromosome 3 pointing to trans-repression in this region.

CONCLUSIONS

Analysis of the molecular signature of trisomy 12 in CLL resulted in: (i) identification of a surrogate marker for PCR (HIP1R); (ii) observation of a gene dosage effect; and (iii) detection of specific underexpression of genes located on chromosome 3. These results should help to improve diagnosis and treatment decisions for patients with CLL and trisomy 12.

Deregulated expression of fat and muscle genes in B-cell chronic lymphocytic leukemia with high lipoprotein lipase expression

Lipoprotein lipase (LPL) is a prognostic marker in B-cell chronic lymphocytic leukemia (B-CLL) related to immunoglobulin V(H) gene (IgV(H))mutational status. We determined gene expression profiles using Affymetrix U133A GeneChips in two groups of B-CLLs selected for either high ('LPL+', n=10) or low ('LPL-', n=10) LPL mRNA expression. Selected genes were verified by real-time PCR in an extended patient cohort (n=42). A total of 111 genes discriminated LPL+ from LPL- B-CLLs. Of these, the top three genes associated with time to first treatment were Septin10, DMD and Gravin (P</=0.01). The relationship of LPL+ and LPL- B-CLL gene expression signatures to 52 tissues was statistically analyzed. The LPL+ B-CLL expression signature, represented by 64 genes was significantly related to fat, muscle and PB dendritic cells (P<0.001). Exploration of microarray data to define functional alterations related to the biology of LPL+ CLL identified two functional modules, fatty acid degradation and MTA3 signaling, as being altered with higher statistical significance. Our data show that LPL+ B-CLL cells have not only acquired gene expression changes in fat and muscle-associated genes but also in functional pathways related to fatty acid degradation and signaling which may ultimately influence CLL biology and clinical outcome.