Integrative prognostic models predict long-term survival after immunochemotherapy in chronic lymphocytic leukemia patients.

Chemoimmunotherapy with fludarabine, cyclophosphamide and rituximab (FCR) can induce long-term remissions in patients with chronic lymphocytic leukemia. Treatment efficacy with Bruton's tyrosine kinase inhibitors was found similar to FCR in untreated chronic lymphocytic leukemia patients with a mutated immunoglobulin heavy chain variable (IGHV) gene. In order to identify patients who specifically benefit from FCR, we developed integrative models including established prognostic parameters and gene expression profiling (GEP). GEP was conducted on n=337 CLL8 trial samples, "core" probe sets were summarized on gene levels and RMA normalized. Prognostic models were built using penalized Cox proportional hazards models with the smoothly clipped absolute deviation penalty. We identified a prognostic signature of less than a dozen genes, which substituted for established prognostic factors, including TP53 and IGHV gene mutation status. Independent prognostic impact was confirmed for treatment, ß2-microglobulin and del(17p) regarding overall survival and for treatment, del(11q), del(17p) and SF3B1 mutation for progression-free survival. The combination of independent prognostic and GEP variables performed equal to models including only established non-GEP variables. GEP variables showed higher prognostic accuracy for patients with long progression-free survival compared to categorical variables like the IGHV gene mutation status and reliably predicted overall survival in CLL8 and an independent cohort. GEP-based prognostic models can help to identify patients who specifically benefit from FCR treatment. The CLL8 trial is registered under EUDRACT-2004- 004938-14 and clinicaltrials gov. Identifier: NCT00281918.

Targeting inhibitor of apoptosis proteins by Smac mimetic elicits cell death in poor prognostic subgroups of chronic lymphocytic leukemia.

Inhibitor of apoptosis (IAP) proteins are highly expressed in chronic lymphocytic leukemia (CLL) cells and contribute to evasion of cell death and poor therapeutic response. Here, we report that Smac mimetic BV6 dose-dependently induces cell death in 28 of 51 (54%) investigated CLL samples, while B-cells from healthy donors are largely unaffected. Importantly, BV6 is significantly more effective in prognostic unfavorable cases with, e.g., non-mutated VH status and TP53 mutation than samples with unknown or favorable prognosis. The majority of cases with 17p deletion (10/12) and Fludarabine refractory cases respond to BV6, indicating that BV6 acts independently of p53. BV6 also triggers cell death under survival conditions mimicking the microenvironment, e.g., by adding CD40 ligand or conditioned medium. Gene expression profiling identifies cell death, NF-κB and redox signaling among the top pathways regulated by BV6 not only in CLL but also in core-binding factor (CBF) acute myeloid leukemia (AML). Consistently, BV6 stimulates production of reactive oxygen species (ROS), which are contributing to BV6-induced cell death, since antioxidants reduce cell death. While BV6 causes degradation of cellular inhibitor of apoptosis (cIAP)1 and cIAP2 and nuclear factor-kappaB (NF-κB) pathway activation in primary CLL samples, BV6 induces cell death independently of caspase activity, receptor-interacting protein (RIP)1 activity or tumor necrosis factor (TNF)α, as zVAD.fmk, necrostatin-1 or TNFα-blocking antibody Enbrel fail to inhibit cell death. Together, these novel insights into BV6-regulated cell death in CLL have important implications for developing new therapeutic strategies to overcome cell death resistance especially in poor prognostic CLL subgroups.

High-resolution genomic profiling of chronic lymphocytic leukemia reveals new recurrent genomic alterations.

To identify genomic alterations in chronic lymphocytic leukemia (CLL), we performed single-nucleotide polymorphism-array analysis using Affymetrix Version 6.0 on 353 samples from untreated patients entered in the CLL8 treatment trial. Based on paired-sample analysis (n = 144), a mean of 1.8 copy number alterations per patient were identified; approximately 60% of patients carried no copy number alterations other than those detected by fluorescence in situ hybridization analysis. Copy-neutral loss-of-heterozygosity was detected in 6% of CLL patients and was found most frequently on 13q, 17p, and 11q. Minimally deleted regions were refined on 13q14 (deleted in 61% of patients) to the DLEU1 and DLEU2 genes, on 11q22.3 (27% of patients) to ATM, on 2p16.1-2p15 (gained in 7% of patients) to a 1.9-Mb fragment containing 9 genes, and on 8q24.21 (5% of patients) to a segment 486 kb proximal to the MYC locus. 13q deletions exhibited proximal and distal breakpoint cluster regions. Among the most common novel lesions were deletions at 15q15.1 (4% of patients), with the smallest deletion (70.48 kb) found in the MGA locus. Sequence analysis of MGA in 59 samples revealed a truncating mutation in one CLL patient lacking a 15q deletion. MNT at 17p13.3, which in addition to MGA and MYC encodes for the network of MAX-interacting proteins, was also deleted recurrently.

SIX2 gene haploinsufficiency leads to a recognizable phenotype with ptosis, frontonasal dysplasia, and conductive hearing loss.

Heterozygous microdeletions of chromosome 2p21 encompassing only the SIX2 gene have been described in two families to date. The clinical phenotype comprised autosomal-dominant inherited frontonasal dysplasia with ptosis in one family. In the second family, conductive hearing loss was the major clinical feature described; however, the affected persons also had ptosis. Here, we present a large family combining all three predescribed features of SIX2 gene deletion. The phenotype in four affected family members in three generations consisted of bilateral congenital ptosis, epicanthus inversus, frontonasal dysplasia with broad nasal bridge and hypertelorism, frontal bossing and large anterior fontanel in childhood, narrow ear canals, and mild conductive hearing loss with onset in childhood. Thus, the phenotypic spectrum of SIX2 haploinsufficiency is widened. Moreover, 2p21 microdeletions with SIX2 haploinsufficiency appear to lead to a recognizable phenotype with facial features resembling blepharophimosis-ptosis-epicanthus inversus syndrome.