Most patients with chronic lymphocytic leukemia (CLL) are diagnosed with early-stage disease and managed with active surveillance. The individual course of patients with early-stage CLL is heterogeneous, and their probability of needing treatment is hardly anticipated at diagnosis. We aimed at developing an international prognostic score to predict time to first treatment (TTFT) in patients with CLL with early, asymptomatic disease (International Prognostic Score for Early-stage CLL [IPS-E]). Individual patient data from 11 international cohorts of patients with early-stage CLL (n = 4933) were analyzed to build and validate the prognostic score. Three covariates were consistently and independently correlated with TTFT: unmutated immunoglobulin heavy variable gene (IGHV), absolute lymphocyte count higher than 15 × 109/L, and presence of palpable lymph nodes. The IPS-E was the sum of the covariates (1 point each), and separated low-risk (score 0), intermediate-risk (score 1), and high-risk (score 2-3) patients showing a distinct TTFT. The score accuracy was validated in 9 cohorts staged by the Binet system and 1 cohort staged by the Rai system. The C-index was 0.74 in the training series and 0.70 in the aggregate of validation series. By meta-analysis of the training and validation cohorts, the 5-year cumulative risk for treatment start was 8.4%, 28.4%, and 61.2% among low-risk, intermediate-risk, and high-risk patients, respectively. The IPS-E is a simple and robust prognostic model that predicts the likelihood of treatment requirement in patients with early-stage CLL. The IPS-E can be useful in clinical management and in the design of early intervention clinical trials.

I n recent years, the outcome of mantle cell lymphoma (MCL) has improved, especially in younger patients, receiving cytarabine-containing chemoimmunotherapy and autologous stem cell transplantation. Nevertheless, a proportion of MCL patients still experience early failure. To identify biomarkers anticipating failure of intensive chemotherapy in MCL, we performed target resequencing and DNA profiling of purified tumor samples collected from patients enrolled in the prospective FIL-MCL0208 phase 3 trial (high-dose chemoimmunotherapy followed by autologous transplantation and randomized lenalidomide maintenance). Mutations of KMT2D and disruption of TP53 by deletion or mutation associated with an increased risk of progression and death, both in univariate and multivariate analysis. By adding KMT2D mutations and TP53 disruption to the MIPI-c backbone, we derived a new prognostic index, the "MIPI-genetic" ("MIPI-

IRC3 is a recurrently mutated gene in chronic lymphocytic leukemia (CLL) but the functional implications of BIRC3 mutations are largely unexplored. Furthermore, little is known about the prognostic impact of BIRC3 mutations in CLL cohorts homogeneously treated with first-line fludarabine, cyclophosphamide, and rituximab (FCR). By immunoblotting analysis, we showed that the non-canonical nuclear factor-κB pathway is active in BIRC3-mutated cell lines and in primary CLL samples, as documented by the stabilization of MAP3K14 and by the nuclear localization of p52. In addition, BIRC3-mutated primary CLL cells are less sensitive to fludarabine. In order to confirm in patients that BIRC3 mutations confer resistance to fludarabine-based chemoimmunotherapy, a retrospective multicenter cohort of 287 untreated patients receiving first-line FCR was analyzed

Richter transformation (RT) is a paradigmatic evolution of chronic lymphocytic leukemia (CLL) into a very aggressive large B cell lymphoma conferring a dismal prognosis. The mechanisms driving RT remain largely unknown. We characterized the whole genome, epigenome and transcriptome, combined with single-cell DNA/RNA-sequencing analyses and functional experiments, of 19 cases of CLL developing RT. Studying 54 longitudinal samples covering up to 19 years of disease course, we uncovered minute subclones carrying genomic, immunogenetic and transcriptomic features of RT cells already at CLL diagnosis, which were dormant for up to 19 years before transformation. We also identified new driver alterations, discovered a new mutational signature (SBS-RT), recognized an oxidative phosphorylation (OXPHOS)high–B cell receptor (BCR)low-signaling transcriptional axis in RT and showed that OXPHOS inhibition reduces the proliferation of RT cells. These findings demonstrate the early seeding of subclones driving advanced stages of cancer evolution and uncover potential therapeutic targets for RT.

Richter's transformation (RT) is an aggressive lymphoma which occurs upon progression from chronic lymphocytic leukemia (CLL). Transformation has been associated with genetic aberrations in the CLL-phase involving TP53, CDKN2A, MYC, and NOTCH1, however a significant proportion of RT cases lack CLL-phase associated events. Here, we report that high levels of AKT phosphorylation occurs both in high-risk CLL patients harboring TP53 and NOTCH1 mutations as well as in RT patients. Genetic over-activation of Akt in the murine Eµ-TCL1 CLL mouse model resulted in CLL to RT with significantly reduced survival and an aggressive lymphoma phenotype. In the absence of recurrent mutations, we identified a profile of genomic aberrations intermediate between CLL and DLBCL. Multi-omics assessment by phosphoproteomic/proteomic and single-cell transcriptomic profiles of this Akt-induced murine RT revealed a S100-protein-defined subcluster of highly aggressive lymphoma cells, which developed from CLL cells, through activation of Notch via Notch ligand expressed by T cells. Constitutively active Notch1 similarly induced RT of murine CLL. We identify Akt activation as an initiator of CLL transformation towards aggressive lymphoma by inducing Notch signaling between RT cells and microenvironmental T cells.

CD49d is a remarkable prognostic biomarker of chronic lymphocytic leukemia (CLL). The cutoff value for the extensively validated 30% of positive CLL cells is able to separate CLL patients into 2 subgroups with different prognoses, but it does not consider the pattern of CD49d expression. In the present study, we analyzed a cohort of 1630 CLL samples and identified the presence of ∼20% of CLL cases (n = 313) characterized by a bimodal expression of CD49d, that is, concomitant presence of a CD49d+ subpopulation and a CD49d− subpopulation. At variance with the highly stable CD49d expression observed in CLL patients with a homogeneous pattern of CD49d expression, CD49d bimodal CLL showed a higher level of variability in sequential samples, and an increase in the CD49d+ subpopulation over time after therapy. The CD49d+ subpopulation from CD49d bimodal CLL displayed higher levels of proliferation compared with the CD49d− cells; and was more highly represented in the bone marrow compared with peripheral blood (PB), and in PB CLL subsets expressing the CXCR4dim/CD5bright phenotype, known to be enriched in proliferative cells. From a clinical standpoint, CLL patients with CD49d bimodal expression, regardless of whether the CD49d+ subpopulation exceeded the 30% cutoff or not, experienced clinical behavior similar to CD49d+ CLL, both in chemoimmunotherapy (n = 1522) and in ibrutinib (n = 158) settings. Altogether, these results suggest that CD49d can drive disease progression in CLL, and that the pattern of CD49d expression should also be considered to improve the prognostic impact of this biomarker in CLL.

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in western countries, with an incidence of approximately 5.1/100,000 new cases per year. Some patients may never require treatment, whereas others relapse early after front line therapeutic approaches. Recent whole genome and whole exome sequencing studies have allowed a better understanding of CLL pathogenesis and the identification of genetic lesions with potential clinical relevance. Consistently, precision medicine plays a pivotal role in the treatment algorithm of CLL, since the integration of molecular biomarkers with the clinical features of the disease may guide treatment choices. Most CLL patients present at the time of diagnosis with an early stage disease and are managed with a watch and wait strategy. For CLL patients requiring therapy, the CLL treatment armamentarium includes both chemoimmunotherapy strategies and biological drugs. The efficacy of these treatment strategies relies upon specific molecular features of the disease. TP53 disruption (including both TP53 mutation and 17p deletion) is the strongest predictor of chemo-refractoriness, and the assessment of TP53 status is the first and most important decisional node in the first line treatment algorithm. The presence of TP53 disruption mandates treatment with biological drugs that inhibit the B cell receptor or, alternatively, the B-cell lymphoma 2 (BCL2) pathway and can, at least in part, circumvent the chemorefractoriness of TP53-disrupted patients. Beside TP53 disruption, the mutational status of immunoglobulin heavy variable (IGHV) genes also helps clinicians to improve treatment tailoring. In fact, patients carrying mutated IGHV genes in the absence of TP53 disruption experience a long-lasting and durable response to chemoimmunotherapy after fludarabine, cyclophosphamide, and rituximab (FCR) treatment with a survival superimposable to that of a matched general population. In contrast, patients with unmutated IGHV genes respond poorly to chemoimmunotherapy and deserve treatment with B cell receptor inhibitors. Minimal residual disease is also emerging as a relevant biomarker with potential clinical implications. Overall, precision medicine is now a mainstay in the management and treatment stratification of CLL. The identification of novel predictive biomarkers will allow further improvements in the treatment tailoring of this leukemia.

Summary In chronic lymphocytic leukaemia (CLL), caution is warranted regarding the clinical implications of immunoglobulin variable heavy chain region (IGHV) rearrangements with a ‘borderline’ (BL) percentage of mutations (i.e. 97–97·9% IGHV identity). We analysed the IGHV mutational status in 759 untreated CLL patients (cohort 1). BL‐CLL (n = 36, 5%) showed a time to first treatment (TFT) similar to that of M‐CLL (n = 338) and significantly longer than that of UM‐CLL (n = 385), despite the enrichment in subset #2 cases. In fact, CLLs belonging to subset #2 (n = 15/759, 2%) were significantly more frequent among BL‐CLLs (n = 5/36, 14%), with a brief TFT. TFT of BL‐CLL remained comparable to that of M‐CLL also considering the 327 CLL patients evaluated at diagnosis. These findings were then validated in an independent cohort 2 of 759 newly diagnosed CLL patients (BL‐CLL: n = 11, 1·4%) and in all newly diagnosed patients from cohorts 1 and 2 (n = 1 086, 84% stage A; BL‐CLL: n = 47, 4·3%). BL‐CLL at diagnosis showed a biological profile comparable to that of M‐CLL with a low frequency of unfavourable prognostic markers, except for a significant enrichment in subset #2. Our data suggest that the prognosis of BL‐CLL is good and similar to that of M‐CLL, with the exception of subset #2 cases.