Citations

Abstract Background. Trisomy 12 (tris12) is a recurrent cytogenetic abnormality in chronic lymphocytic leukemia (CLL), occurring in approximately 15-20% of cases, often as the unique cytogenetic alteration, that is usually considered a clonal driver lesion occurring early in CLL evolution. In the Dohner hierarchical categorization, tris12 CLL are identified as having an intermediate prognostic risk, although recent reports suggest a more complex and heterogeneous clinical behavior. Compared to CLL lacking this cytogenetic abnormality, tris12 CLL show more atypical morphology and immunophenotype, more frequent expression of the negative prognostic markers CD49d and CD38, and presence of NOTCH1 mutations and an unmutated (UM) IGHV gene status. The increased fraction of tris12 CLL carrying adverse prognostic features is in contrast to the intermediate clinical behavior associated with most tris12 CLL cases. Aim. To perform a comprehensive evaluation of the clinical impact of the major genetic, immunogenetic and immunophenotypic prognostic markers in tris12 CLL. Methods. The study was based on a multicenter series of tris12 CLL defined according to Dohner (n=283, including 73 cases also bearing del13q), and a comparison group (control) of 553 cases with either del13q (n=308) or without any cytogenetic abnormality (no del17p, del11q, tris12, del13q, n=245). Median follow-up of patients in the tris12 and control groups were 4 years (range 0-22) and 7 years (range 0-28), with 54% and 57% treated patients, and 18% and 15% deaths, respectively. Patient characterization included modified Rai stage, CD49d (CD49dhigh, ≥30% positive cells by flow cytometry), CD38 (CD38high, ≥30% positive cells by flow cytometry) and ZAP-70 (ZAP-70high, ≥20% positive cells by flow cytometry) expression, and IGHV mutational status (mutated, M, or UM according to the 2% cutoff). TP53, BIRC3, NOTCH1 andSF3B1 mutations were screened either at diagnosis or before therapy by NGS with at least 1000X coverage and 1% of sensitivity. Groups were compared by chi-square test; overall survival (OS) was computed from diagnosis to death or censored at last observation, and analyzed by Cox regression analysis. Results. Comparing the tris12 and the control groups, median age was 64 years (range 30-92) vs 66 years (range 33-92), male gender 55% vs 56% (p=0.86), the modified Rai stage was early in 52% vs 54%, intermediate in 41% vs 42% and advanced in 7% vs 4% (p=0.20). As previously reported, tris12 CLL were characterized by a higher prevalence of cases expressing CD49d (85% vs 31%) and CD38 (62% vs 17%; all p<0.0001), and of UM IGHV cases (55% vs 25%, p<0.0001). Analysis of recurrent mutations highlighted a higher prevalence of NOTCH1 mutations (26% vs 8%, p<0.0001) and of BIRC3 mutations (21% vs 1%, p<0.0001) in tris12 vs control group CLL. Conversely, no differences were found in the fraction of cases with TP53 mutations (3% vs 4%, p=0.38) or SF3B1 mutations (7% vs 7%, p=0.89), and in cases expressing ZAP-70 (62% vs 52%, p=0.09). The impact of these features on OS was tested by univariate analysis: in tris12 CLL, only the UM IGHV gene status predicted shorter OS (HR=2.37, p=0.0063), while none of the other characteristics reaching statistical significance as OS predictors (CD49d HR=1.36, p=0.36; CD38 HR=0.42, p=0.052; ZAP-70 HR=3.12, p=0.07; TP53 HR=2.33, p=0.25; NOTCH1 HR=1.40, p=0.22; SF3B1 HR=2.05, p=0.17; BIRC3 HR=1.22, p=0.61). On the other hand, in the control cohort, a significantly higher HR was found for CD49d (HR 3.11, p<0.0001) and CD38 (HR 3.45, p<0.0001) expression, TP53 (HR 2.88, p=0.0026), NOTCH1 (HR 3.57, p<0.0001), and SF3B1 (HR 2.57, p=0.0038) mutations, as well as for the UM IGHV gene status (HR=2.81, p<0.0001), but not for ZAP-70 expression and BIRC3 mutations (HR=1.74 and HR=1.91, p=0.15 and p=0.37, respectively). Conclusions. Mutational status of IGHV genes was the sole prognostic factor able to stratify OS in tris12 CLL. Despite the high frequency of NOTCH1 and BIRC3 mutations, as well as of CD49d and CD38 overexpression, these markers failed to convey a prognostic risk in tris12 CLL. The lack of a significant clinical impact for TP53 and SF3B1 mutations might be partly explained by the low number of mutated cases combined with a relative short follow up in our tris12 cohort. These findings are in keeping with the hypothesis of a different patho-biological mechanism occurring in tris12 CLL, which however remains to be fully elucidated. Disclosures D'Arena: Janssen-Cilag: Honoraria. Rossi:Gilead: Honoraria, Research Funding; Abbvie: Honoraria; Janseen: Honoraria. Gaidano:Janssen: Consultancy, Honoraria, Speakers Bureau; Gilead: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Speakers Bureau; Morphosys: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria. Shanafelt:Genentech: Research Funding; Janssen: Research Funding; Celgene: Research Funding; GlaxoSmithkKine: Research Funding; Pharmacyclics: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

Abstract Abstract 3871 Background. A number of investigators have provided data supporting the value of CD49d expression on B leukemic cells in chronic lymphocytic leukemia (CLL) as independent prognostic variable. These studies used a variety of clinical end points including overall survival (OS), time to treatment (TTT) or treatment free survival (TFS). The factors included in multivariate analyses of these studies also differed. Unresolved issues regarding the prognostic value of CD49d assessment in CLL included the choice of the optimal cut-off to define positivity and CD49d prognostic value in patients subsets defined by other standard prognostic factors. Aim. To perform meta-analysis using individual patient level data from studies of CD49d expression to evaluate its ability to predict OS (primary end-point) and TTT/TFS (secondary end-point). Methods. Studies published by 30 April 2011, reporting an association of high CD49d expression on B CLL cells, measured by flow cytometry, and end-points were identified by Medline search. Additionally, we performed a manual review of abstracts presented at the congress of the American Society of Hematology from 2006 to 2010. CD49d was used as a categorical variable, as coded in original studies. Results. We identified 6 published studies and one abstract for inclusion. All authors agreed to provide individual data on the patients in these publications as well as unpublished data on additional patients to be used for replication analysis. Four authors also submitted updated follow-up data. We collected the following variables: date of diagnosis, OS, TTT/TFS, CD49d, CD38, ZAP-70, immunoglobulin mutational (IGHV) status, del17p and del11q chromosomal aberrations, age, stage, ALC, and β2 microglobulin concentration. Data from 3146 individual patients was available with 261 subsequently excluded due to missing end point and/or CD49d data. Of 2771 patients with valid data, 1405 (51%) were included in the previous publications and 1366 (49%) were unpublished. Before starting analyses a decision was made to perform meta-analysis on published data and use data from previously unpublished data as a validation cohort. Pooled CD49d hazard ratio for OS was 2.62 (1.88–3.64). In bivariate analysis, the prognostic value of CD49d was confirmed and of comparable value in patients subsets defined by CD38 and ZAP-70 expression, IGHV status, unfavorable chromosomal aberrations. Finally, we performed a multivariate analysis including CD49d, CD38, ZAP-70, IGHV status, del17p and del11q. CD49d was significantly associated with shorter overall survival in this adjusted model, with a hazard ratio of 2.47(1.17–5.21). Inspection of Martingale residuals plots of CD49d in each study failed to show a recognizable cut-point. CD49d cut-points previously adopted in published studies (30% and 45%) were subjected to validation in the cohort of 1366 unpublished patients. The Cox model with 45% cut-off had a slight greater hazard ratio (2.73 vs 2.65, log-rank p<0.0001). Only 4% of patients changed prognostic category after swapping the cut-off from 45% to 30%. Conclusions. Preliminary results of a meta-analysis using individual patient data from >1400 patients confirm the association of high CD49d expression with short OS independent of other prognostic parameters. While the 45% cut-off has a marginal better prognostic power, the 30% cut-off has the advantage of being already in use for CD38 and generally adopted for other surface antigens in chronic leukemia immunophenotyping. These findings may have implication for patient's stratification in future prospective studies and potential therapeutic efforts to target CD49d or CD49d signaling. Disclosures: Shanafelt: Genentech: Research Funding; Glaxo-Smith-Kline: Research Funding; Cephalon: Research Funding; Hospira: Research Funding; Celgene: Research Funding; Polyphenon E International: Research Funding. Burger:Pharmacyclics: Consultancy, Research Funding.

Abstract Purpose: We sought to investigate whether B cell receptor immunoglobulin (BcR IG) stereotypy is associated with particular clinicobiological features among chronic lymphocytic leukemia (CLL) patients expressing mutated BcR IG (M-CLL) encoded by the IGHV4-34 gene, and also ascertain whether these associations could refine prognostication. Experimental Design: In a series of 19,907 CLL cases with available immunogenetic information, we identified 339 IGHV4-34–expressing cases assigned to one of the four largest stereotyped M-CLL subsets, namely subsets #4, #16, #29 and #201, and investigated in detail their clinicobiological characteristics and disease outcomes. Results: We identified shared and subset-specific patterns of somatic hypermutation (SHM) among patients assigned to these subsets. The greatest similarity was observed between subsets #4 and #16, both including IgG-switched cases (IgG-CLL). In contrast, the least similarity was detected between subsets #16 and #201, the latter concerning IgM/D-expressing CLL. Significant differences between subsets also involved disease stage at diagnosis and the presence of specific genomic aberrations. IgG subsets #4 and #16 emerged as particularly indolent with a significantly (P &lt; 0.05) longer time-to-first-treatment (TTFT; median TTFT: not yet reached) compared with the IgM/D subsets #29 and #201 (median TTFT: 11 and 12 years, respectively). Conclusions: Our findings support the notion that BcR IG stereotypy further refines prognostication in CLL, superseding the immunogenetic distinction based solely on SHM load. In addition, the observed distinct genetic aberration landscapes and clinical heterogeneity suggest that not all M-CLL cases are equal, prompting further research into the underlying biological background with the ultimate aim of tailored patient management. Clin Cancer Res; 23(17); 5292–301. ©2017 AACR.