Shorter Time To First Treatment Research Articles

MicroRNA Profiling as a Predictive Indicator for Time to First Treatment in Chronic Lymphocytic Leukemia: Insights from the O-CLL1 Prospective Study

A “watch and wait” strategy, delaying treatment until active disease manifests, is adopted for most CLL cases; however, prognostic models incorporating biomarkers have shown to be useful to predict treatment requirement. In our prospective O-CLL1 study including 224 patients, we investigated the predictive role of 513 microRNAs (miRNAs) on time to first treatment (TTFT). In the context of this study, six well-established variables (i.e., Rai stage, beta-2-microglobulin levels, IGVH mutational status, del11q, del17p, and NOTCH1 mutations) maintained significant associations with TTFT in a basic multivariable model, collectively yielding a Harrell’s C-index of 75% and explaining 45.4% of the variance in the prediction of TTFT. Concerning miRNAs, 73 out of 513 were significantly associated with TTFT in a univariable model; of these, 16 retained an independent relationship with the outcome in a multivariable analysis. For 8 of these (i.e., miR-582-3p, miR-33a-3p, miR-516a-5p, miR-99a-5p, and miR-296-3p, miR-502-5p, miR-625-5p, and miR-29c-3p), a lower expression correlated with a shorter TTFT, whereas in the remaining eight (i.e., miR-150-5p, miR-148a-3p, miR-28-5p, miR-144-5p, miR-671-5p, miR-1-3p, miR-193a-3p, and miR-124-3p), the higher expression was associated with shorter TTFT. Integrating these miRNAs into the basic model significantly enhanced predictive accuracy, raising the Harrell’s C-index to 81.1% and the explained variation in TTFT to 63.3%. Moreover, the inclusion of the miRNA scores enhanced the integrated discrimination improvement (IDI) and the net reclassification index (NRI), underscoring the potential of miRNAs to refine CLL prognostic models and providing insights for clinical decision-making. In silico analyses on the differently expressed miRNAs revealed their potential regulatory functions of several pathways, including those involved in the therapeutic responses. To add a biological context to the clinical evidence, an miRNA–mRNA correlation analysis revealed at least one significant negative correlation between 15 of the identified miRNAs and a set of 50 artificial intelligence (AI)-selected genes, previously identified by us as relevant for TTFT prediction in the same cohort of CLL patients. In conclusion, the identification of specific miRNAs as predictors of TTFT holds promise for enhancing risk stratification in CLL to predict therapeutic needs. However, further validation studies and in-depth functional analyses are required to confirm the robustness of these observations and to facilitate their translation into meaningful clinical utility.

Abstract LB345: Correlating the blood immune repertoire and clinical features of del17p CLL patients

Abstract Introduction: Deletion in the short arm of chromosome 17 (del17p) is a strong, negative prognostic biomarker found in about eight percent of patients with untreated chronic lymphocytic leukemia (CLL). CLL patients with del17p exhibit resistance to therapy, accelerated disease progression, and global immunodeficiency. It is unclear the extent to which global immunodeficiency impacts disease course and therapy outcomes. The goal of this study was to document the blood immune repertoire of patients with untreated CLL who have del17p and associate with clinical features, time to first treatment (TFT), and overall survival (OS). Methods: Biobanked blood samples from treatment-naïve del17p CLL patients (n = 58) and age-matched controls (n = 5) were obtained. B cells and T cells were analyzed with comprehensive, cell type-specific flow cytometry panels and visualized with unbiased dimensionality reduction. Lab values were log-transformed and compared using t-tests and one-way ANOVAs. TFT was calculated from date of sample collection to date of first CLL-directed therapy or last known untreated date; OS was calculated from date of sample collection to death or last known alive status. Cox proportional hazards regression analyses (results reported as hazard ratio [HR] and 95% confidence interval [CI]) were employed to identify associations of lab values with OS and TFT. Results: Patients with del17p CLL had increased proportions of T regulatory cells (Tregs) among total CD4+ T cells compared to controls (CLL 11.1%, control 5.7%, p = 0.05). A higher proportion of CD8+ T cells was associated with longer TFT (HR 0.57, 95%CI 0.36-0.89); in contrast, higher proportions of TIGIT+ (HR 1.83, 95%CI 1.03-3.28) and TIM3+ conventional (non-Treg) CD4+ T cells were associated with shorter TFT (HR 1.70, 95%CI 1.02-2.84). A higher proportion of PD1+ CD8+ T cells was associated with shorter OS (HR 1.79, 95%CI 1.05-3.06), in addition to PD1+ conventional CD4+ T cell proportion (HR 2.21, 95%CI 1.06-4.60). CLL B cells expressed PD-1 and inducible T cell costimulator (ICOS) at significantly lower median fluorescence intensities (MFIs) than control B cells (p < 0.0001 for both). The CXCR5+ MFI (HR 1.0002, 95%CI 1.0001-1.003) and CD23+ MFI (HR 1.88, 95%CI 1.01-3.50) of CLL B cells were associated with shorter TFT. Discussion: In this cohort of treatment-naïve del17p CLL patients, we determined that patients with higher proportions of exhausted CD4+ and CD8+ T cell phenotypes had significantly shorter OS. Cytotoxic T cell proportion positively associated with TFT, whereas proportions of CD4+ T cell exhaustion phenotypes negatively associated with TFT. Higher CXCR5+ and CD23+ MFIs of CLL B cells also associated with shorter TFT. The preliminary findings from our study suggest that the blood immune repertoire has strong associations with clinically relevant outcomes such as time to first treatment and overall survival in patients with untreated del17p CLL. Citation Format: Ethan J. Katcher, Kim A. Gwin, Sameer A. Parikh, Kari G. Rabe, Petra K. Lothert, Preeti Trisal, Esteban Braggio, Susan L. Slager, Nicholas Strong, Daniel L. Van Dyke, Zhiquan Wang, C. Chris Huang, Anita K. Gandhi, Kay L. Medina, Neil E. Kay. Correlating the blood immune repertoire and clinical features of del17p CLL patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB345.

Chronic Lymphocytic Leukemia (CLL) with Borderline Immunoglobulin Heavy Chain Mutational Status, a Rare Subgroup of CLL with Variable Disease Course.

Chronic lymphocytic leukemia (CLL) exhibits substantial variability in disease course. The mutational status of the B-cell receptor immunoglobulin heavy variable (IGHV) chain is a critical prognostic factor, categorizing patients into mutated (M-IGHV) and unmutated (U-IGHV) groups. Recently, a third subgroup with borderline mutational status (BL-IGHV) has been identified, comprising approximately 5% of CLL cases. This study retrospectively analyzes the outcomes of 30 BL-IGHV mutated patients among a cohort of 653 CLL patients, focusing on time to first treatment (TTFT) and overall survival (OS). BL-IGHV patients had a short TTFT similar to U-IGHV patients (median 30.2 vs. 34 months; p = 0.9). Conversely, the OS of BL-IGHV patients resembled M-IGHV patients (median NR vs. 258 months; p = 1). Despite a similar incidence in unfavorable prognostic factors, the TTFT was shorter compared to other published cohorts. However, striking similarities with other experiences suggest that BL-IGHV mutated patients share common biological characteristics, biased IGHV gene usage and BCR subset frequency. These findings also underscore the need for multicentric efforts aggregating data on BL-IGHV CLL in order to elucidate its disease course and optimize therapeutic approaches for this rare subgroup. Until then, predicting outcomes and optimal management of BL-IGHV CLL will remain challenging.

CXC chemokine ligand 13 and galectin-9 plasma levels collaboratively provide prediction of disease activity and progression-free survival in chronic lymphocytic leukemia

The clinical outcome of lymphocytic leukemia (CLL) is quite heterogeneous. The purpose of this observational study was to investigate the clinical merit of measuring plasma galectin-9 and CXCL-13 concentrations as predictors of CLL activity, prognosis, and early indicators of therapeutic response. These biomarkers were compared with other prognostic indicators, progression-free survival (PFS), time to first treatment (TTT), and overall survival (OS) over a follow-up period (4 years). First, plasma galectin-9 and CXCL-13 concentrations were analyzed in CLL patients at the time of diagnosis as well as healthy controls. Compared to controls, CLL patients had significantly higher serum levels of CXCL-13 and galectin-9. Second, we observed that CLL patients with high soluble CXCL-13 and galectin-9 levels had advanced clinical stages, poor prognosis, 17p del, short PFS, short TTT, and therapy resistance. The levels of CXCL-13, β2-microglobulin, LDH, CD38%, and high grade of Rai-stage were all strongly correlated with the galectin-9 levels. Soluble CXCL-13 and galectin-9 had very good specificity and sensitivity in detecting CLL disease progression and high-risk patients with the superiority of galectin-9 over CXCL-13. Although the two biomarkers were equal in prediction of TTT and treatment response, the soluble CXCL13 was superior in prediction of OS. High CXCL-13 and galectin-9 plasma levels upon CLL diagnosis are associated with disease activity, progression, advanced clinical stages, short periods of PFS, short TTT, and unfavorable treatment response.

Chronic Lymphoproliferative Disorder of Natural Killer Cells: Patient Characteristics, Laboratory Features, and Clinical Outcomes

Introduction: Chronic lymphoproliferative disorder of natural killer cells (CLPD-NK) is a rare form of large granular lymphocytic leukemia. The clinical characteristics and outcomes of patients (pts) with CLPD-NK in the literature are limited. We aim to describe the patient characteristics, laboratory features, and clinical outcomes of CLPD-NK by reporting on, to our knowledge, the largest single-center cohort of CLPD-NK in the United States. Methods: We retrospectively identified Mayo Clinic pts with CLPD-NK, defined per the WHO 5 th edition and 2022 International Consensus Classification. We conducted chart review to collect clinical and laboratory data. Overall survival (OS) was plotted using Kaplan-Meier. Time to first treatment (TTFT) was displayed using cumulative incidence methodology accounting for competing risk of death. Univariable Cox regression models investigated associations between patient characteristics and outcomes (OS and TTFT). Results: We identified 45 pts who were diagnosed with CLPD-NK between 1997 and 2022. The median age at diagnosis was 69 years (range: 25-90) and 32 pts (71%) were male. At the time of diagnosis, 10 pts (22%) had a concomitant autoimmune disorder and 9 (20%) had laboratory evidence of a serologic abnormality (monoclonal gammopathy, rheumatoid factor, etc.). In addition, 10 pts (22%) had a prior diagnosis of a hematologic malignancy and 12 (27%) had a prior diagnosis of a solid tumor. Clinically, 4 pts (9%) had B symptoms, 15 (33%) had splenomegaly, and 13 (29%) were transfusion dependent. At diagnosis, median hemoglobin (hgb) was 10.2 g/dL, with 25 pts (56%) showing a hgb <11g/dL and 8 (18%) demonstrating a hgb <8 g/dL. The median platelet count was 202x10^9/L, with 12 pts (27%) demonstrating a platelet count <150x10^9/L. The median white blood cell count was 5.8x10^9/L. The median absolute neutrophil count (ANC) was 1.2x10^9/L, with 29 pts (64%) demonstrating an ANC <1.5x10^9/L. The median absolute lymphocyte count (ALC) was 3.8x10^9/L, with 20 pts (44%) demonstrating an ALC >4x10^9/L. The median absolute abnormal NK cell count per flow cytometry was 2.2x10^9/L. Flow cytometry revealed killer cell immunoglobulin-like receptor (KIR) restriction in all pts, with 27 (61%) lacking KIR expression and 17 (39%) demonstrating KIR restriction in CD158a, CD158b, and/or CD158e. CD7 expression was present in 42 pts (93%; 31% dim/partial), CD8 expression was present in 22 (49%; 42% d/p), CD56 expression was present in 17 (39%; 23% d/p), CD57 expression was present in 26 (59%; 46% d/p), CD94 expression was present in 33 (77%; 7% d/p), and NKG2A expression was present in 21 (50%; 5% d/p). Bone marrow examination (n=30) revealed that the median number of NK infiltrate was 11% (range: 5-40%) of cellularity, with 20 demonstrating an intrasinusoidal infiltrative pattern. The median follow-up was 41 months (mo), and 23 pts required at least one line of treatment. Treatment indications included anemia (39%), neutropenia (4%), bi/pancytopenia (39%), lymphocytosis (4%), or other (13%). The median TTFT was 32 mo (95% CI 2-93 mo). Hgb <11g/dL was associated with a shorter TTFT (9.7 vs 187 mo); however, neutropenia and thrombocytopenia were not associated with TTFT. For first-line treatment, in addition to frequent steroid use, 16 pts (70%) received a methotrexate-based regimen, 6 (26%) received a cyclophosphamide-based regimen, and 1 (4%) received a cyclosporine-based regimen. The median TTFT was not reached. Of those who required systemic treatment, 9 pts required a second-line therapy. The median OS from diagnosis was 162 mo (95% CI: 84-not estimable, NE), with 33 pts alive at last follow-up (Figure 1a). Increasing age (HR 1.2, 95% CI 1.1-1.3, p=0.002) and lack of CD94 expression (HR 5.6, 95% 1.3-25.0, p=0.02) were associated with worse OS. In the 23 pts who required treatment, the median OS from treatment initiation was 84 mo (95% CI: 52-NE) (Figure 1b). Conclusions: In this large cohort of 45 pts, the majority had neutropenia and anemia, and approximately half required systemic treatment. Estimated median OS from diagnosis exceeded a decade for the entire cohort and was seven years after treatment initiation. Anemia was associated with a shorter TTFT, while increasing age and lack of CD94 expression were associated with worse OS. This rare disease warrants additional investigations to understand optimal management and improve outcomes, especially for those requiring treatment.

XPO1 mutations identify early-stage CLL characterized by shorter time to first treatment and enhanced BCR signalling.

Here we evaluated the epigenomic and transcriptomic profile of XPO1 mutant chronic lymphocytic leukaemia (CLL) and their clinical phenotype. By ATAC-seq, chromatin regions that were more accessible in XPO1 mutated CLL were enriched of binding sites for transcription factors regulated by pathways emanating from the B-cell receptor (BCR), including NF-κB signalling, p38-JNK and RAS-RAF-MEK-ERK. XPO1 mutant CLL, consistent with the chromatin accessibility changes, were enriched with transcriptomic features associated with BCR and cytokine signalling. By combining epigenomic and transcriptomic data, MIR155HG, the host gene of miR-155, and MYB, the transcription factor that positively regulates MIR155HG, were upregulated by RNA-seq and their promoters were more accessible by ATAC-seq. To evaluate the clinical impact of XPO1 mutations, we investigated a total of 957 early-stage CLL subdivided into 3 independent cohorts (N = 276, N = 286 and N = 395). Next-generation sequencing analysis identified XPO1 mutations as a novel predictor of shorter time to first treatment (TTFT) in all cohorts. Notably, XPO1 mutations maintained their prognostic value independent of the immunoglobulin heavy chain variable status and early-stage prognostic models. These data suggest that XPO1 mutations, conceivably through increased miR-155 levels, may enhance BCR signalling leading to higher proliferation and shorter TTFT in early-stage CLL.

A comprehensive assessment of lymphocyte subsets, their prognostic significance, and changes after first-line therapy administration in patients with chronic lymphocytic leukemia.

In chronic lymphocytic leukemia (CLL), changes in the peripheral blood lymphocyte subsets play an important role in disease progression and infectious complications. The impact of chemoimmunotherapy (CIT) on these changes has not been extensively studied METHODS: We used multi-color flow cytometry, to prospectively measure absolute and relative numbers of CD4+ and CD8+ T-cells and their subsets in 45 patients with indolent untreated CLL, 86 patients indicated for first-line treatment, and 34 healthy controls. In 55 patients, we analyzed the impact of CIT RESULTS: CLL patients had a significant increase in most cell populations in comparison to controls. Progression of CLL was characterized by significantly elevated counts with the exception of a lower percentage of naïve T-cells. After treatment, the percentage of naïve T-cells further decreased at the expense of effector memory T-cells (TEM). In patients with indolent CLL, higher percentages of naïve CD4+ (p= 0.0026) and naïve CD8+ (p= 0.023) T-cells were associated with a longer time to first treatment (TTFT). The elevation of CD4+ central memory T-cells (TCM) (p= 0.27) and TEM (p= 0.003) counts and a higher percentage of CD4+ TEM (p= 0.0047), were linked with shorter TTFT. In treated patients, increased regulatory T-cells count was associated with shorter time to next treatment (TTNT) (p= 0.042), while higher CD4+ TCM count with shorter TTNT (p= 0.035) and shorter overall survival (p= 0.041). Our results indicate that naïve cell depletion and CD4+ TCM and TEM increases are detrimental to CLL patients' prognosis.

Development of a Novel Chromatin Activation Score As a Powerful Independent Prognostic Factor in Chronic Lymphocytic Leukemia

Background & Aim: In a previous study, we identified a signature of 498 regulatory regions with de novo increased H3K27ac levels (a mark of chromatin activation) in patients with chronic lymphocytic leukemia (CLL), which seemed to be present in all cases studied (Beekman et al., Nat Med 2018). In this abstract, we show that such de novo chromatin activation is not stable among CLL patients but heterogeneous, and therefore, we aim at exploring whether such heterogeneity has a biological and clinical impact. Results: The signature of 498 de novo active regulatory regions was related to 434 specific H3K27ac peaks based on chromatin immunoprecipitation sequencing (ChIPseq) data from 104 CLLs. Analyzing the signal variability among patients, we observed a high degree of heterogeneity. An unsupervised clustering revealed two different sets of regions whose mean H3K27ac signal was associated with time to first treatment (TTFT) using a univariate Cox model. In detail, a higher mean H3K27ac intensity was associated with a shorter TTFT in one of the sets (P=0.001 and hazard ratio (HR)=3.5) while, intriguingly, showed a trend towards longer TTFT (P=0.09 HR=0.6) in the other set. These findings suggest that not only disease progression but also disease stability seem to be active processes in CLL involving de novo chromatin changes. Then, we argued that the clinical behavior of CLL patients could be better captured by the balance between the activation levels of these two sets of regions. Indeed, the ratio of both means was statistically more significant (P=1.4x10-9 HR=15.4). Next, we further refined these groups by selecting individual regions associated with shorter (HR>1, 77 peaks) or longer (HR<1, 144 peaks) TTFT (FDR 0.2). We subsequently defined the score SPP as the mean signal in the pro-progressive (PP) group (HR>1), the score SPS as the mean signal in the pro-stable (PS) disease group (HR<1), and SB as their ratio. Ultimately, this led to an improvement of the statistical significance of the SB with TTFT (P=1.4x10-14 HR=8.6). From a biological perspective, we explored the validity of the SB performing ChIPseq for H3K27ac in 10 primary CLLs before and after a co-culture system inducing strong proliferation (Mangolini et al., Nat Comms in press). In these experiments, we observed an increased SB (P<10-3) that was mostly associated with a decreased SPS while maintaining the SPP levels. To further validate the biological implications of our findings, we mined RNAseq data in 64 cases with concurrent ChIPseq experimentation. We identified target genes whose expression levels correlated with H3K27ac levels (43 genes associated with the PP regions and 62 target genes associated with the PS regions). Both lists included genes previously described in CLL (e.g. CTLA4, FMOD or KSR2). Analogously to H3K27ac, we defined three new scores based on expression levels: SPP-exp, SPS-exp and SB-exp. These scores highly correlated with the H3K27ac-based scores (Pearson r between 0.82 to 0.88). Interestingly, cases with higher SB-exp were enriched in TNF-α and NF-κB pathways and in RELB, FOS, JUN, JUNB and EGR1 transcription factors regulons. We also identified 21 genetic driver alterations related to a higher SB-exp including trisomy 12, 11q loss and mutations in IGLV3-21R110, ATM, SF3B1, NOTCH1 and U1. Finally, we evaluated the potential of SB and SB-exp as independent prognostic factors in multivariate models. In the ChIPseq series (n=104), SB was significant independently of the IGHV mutational status, Binet stage and number of genetic driver alterations. Similarly, using three independent CLL series of gene expression data (n=110, 174 and 140), we observed that the SB-exp was a highly significant prognostic factor independent from IGHV status, Binet stage and number of drivers. To favour potential clinical translation, we generated a reduced SB-exp with only 12 genes which maintained the clinical impact. Conclusions: This study revealed an unexpected heterogeneity within de novo active chromatin regions in CLL, and that such heterogeneity has a dual clinical impact on CLL. A balance score between regions related to the two tendencies (i.e. more progressive vs more stable disease) identified groups of patients with different biological features. Finally, using both chromatin and gene expression data as a surrogate, the balance score was a highly significant independent prognostic factor in independent CLL series.

P624: CHROMOTHRIPSIS IN PATIENTS WITH CLL AND COMPLEX KARYOTYPE: PATTERNS OF ABERRATIONS AND PROGNOSTIC VALUE

Background: Chromothripsis is a unique catastrophic event found in 1-5% of chronic lymphocytic leukemia (CLL) patients, associated with poor prognostic factors and short survival (Edelmann et al, 2012; Puente et al, 2015; Leeksma et al, 2021). It is characterized by the presence of multiple genomic rearrangements in one chromosome, resulting in oscillating switches between 2-3 copy number states by chromosomal microarrays (CMA) or next-generation sequencing (Stephens et al, 2011). Optical genome mapping (OGM) is a new method based on the imaging of long DNA molecules (>250kb) labelled at specific motifs, generating a unique pattern. This allows mapping of the genomic location of each molecule and detection of structural and numerical chromosomal abnormalities with high resolution and sensitivity. Aims: 1. To analyze the genome complexity associated with chromothripsis and the patterns of rearrangements detected by OGM; 2. To determine the prognostic impact of chromothripsis in a cohort of CLL patients enriched in complex karyotypes (CK). Methods: A total of 33 patients with chromothripsis detected by CMA were included: 11 with chromothripsis-like patterns (≥7 switches), 22 with classical chromothripsis (≥10 switches). Nine of the cases were studied with OGM (Bionano Genomics). Clinico-biological features and time to first treatment (TTFT) were analyzed. Results were compared with a cohort of 129 patients showing CK without chromothripsis (control group) (Ramos-Campoy et al, 2021). Results: All patients with chromothripsis showed a high genomic complexity (30/33 with CK by chromosome banding analysis and 3/33 classified as complex by CMA [range: 10-24 CNV, being at least three of them >5Mb (range: 3-6)]. Forty-six chromothriptic events were identified. These affected 1-4 chr/patient, but a single chromosome was involved in 25/33 patients (76%). Chromothripsis was distributed throughout all chromosomes, most frequently affecting 3 (n=5), 6 (n=5) and 13 (n=5). The events were mainly multiple losses (25/46) or alternated gains and losses (19/46). Size and coordinates of CNVs detected by OGM and CMA were highly concordant. OGM detected multiple rearrangements cryptic by CMA (median: 9/chromothriptic event). Two patterns of chromothripsis-related rearrangements were identified: one clustered in the chromothriptic region (3/9) and the other involving both chromothriptic and non-chromothriptic chromosomes (range: 1-6 chr) (6/9). One patient showed 36 rearrangements throughout the genome, suggesting the coexistence of chromothripsis and chromoplexy, characterized by the presence of multiple chained translocations (Figure). Patients with chromothripsis showed a higher frequency of TP53del/mut (70% vs 39%; p=0.001) and a shorter TTFT (15m vs 2m; p=0.013) than the control group. No differences were observed for IGHV and del(11q) status. When stratifying patients based on TP53 status, the presence of chromothripsis was not associated with shorter TTFT. In the multivariate analysis including TP53, genomic complexity by CMA and chromothripsis, only TP53 was statistically significant (HR=1.6; p=0.029). Image:Summary/Conclusion: 1. Chromothriptic events involve multiple loci in CLL patients; 2. OGM allows not only the detection of CNV but also the identification of two rearrangement patterns associated with chromothripsis (clustered or involving non-chromothriptic chromosomes) whose clinical impact should be further explored. 3. In CLL patients with CK, the adverse prognosis of chromothripsis is associated with a higher frequency of TP53del/mut.

Lymphocyte Doubling Time As A Key Prognostic Factor To Predict Time To First Treatment In Early-Stage Chronic Lymphocytic Leukemia.

The prognostic role of lymphocyte doubling time (LDT) in chronic lymphocytic leukemia (CLL) was recognized more than three decades ago when the neoplastic clone’s biology was almost unknown. LDT was defined as the time needed for the peripheral blood lymphocyte count to double the of the initial observed value. Herein, the LDT prognostic value for time to first treatment (TTFT) was explored in our prospective O-CLL cohort and validated in in two additional CLL cohorts. Specifically, newly diagnosed Binet stage A CLL patients from 40 Italian Institutions, representative of the whole country, were prospectively enrolled into the O-CLL1-GISL protocol (clinicaltrial.gov identifier: NCT00917540). Two independent cohorts of newly diagnosed CLL patients recruited respectively at the Division of Hematology in Novara, Italy, and at the Hospital Clinic in Barcelona, Spain, were utilized as validation cohorts. In the training cohort, TTFT of patients with LDT >12 months was significantly longer related to those with a shorter LDT. At Cox multivariate regression model, LDT ≤ 12 months maintained a significant independent relationship with shorter TTFT along with IGHV unmutated (IGHVunmut) status, 11q and 17p deletions, elevated β2M, Rai stage I-II, and NOTCH1 mutations. Based on these statistics, two regression models were constructed including the same prognostic factors with or without the LDT. The model with the LTD provided a significantly better data fitting (χ2 = 8.25, P=0.0041). The risk prediction developed including LDT had better prognostic accuracy than those without LDT. Moreover, the Harrell’C index for the scores including LDT were higher than those without LDT, although the accepted 0.70 threshold exceeded in both cases. These findings were also confirmed when the same analysis was carried out according to TTFT’s explained variation. When data were further analyzed based on the combination between LDT and IGHV mutational status in the training and validation cohorts, IGHVunmut and LDT>12months group showed a predominant prognostic role over IGHVmut LTD ≤ 12 months (P=0.006) in the O-CLL validation cohort. However, this predominance was of borden-line significance (P=0.06) in the Barcelona group, while the significant prognostic impact was definitely lost in the Novara group. Overall, in this study, we demonstrated that LDT could be re-utilized together with the more sophisticated prognostic factors to manage the follow-up plans for Binet stage A CLL patients.

Abstract 884: Tumor mutational load derived from recurrently mutated genes in chronic lymphocytic leukemia (CLL) predicts time-to-first treatment in high-count monoclonal B-cell lymphocytosis (HC MBL)

Abstract Clinical practice guidelines recommend that individuals with HC MBL are evaluated annually for evidence of progression as it has been shown that they progress to develop CLL requiring therapy at a rate of 1-5%/year. Next-generation sequencing identified 59 genes recurrently mutated in CLL, and we previously showed that the tumor mutational load (TML), i.e., the total number of these genes mutated, is associated with a shorter time to first treatment (TTT) among 112 HC MBLs independent of the CLL international prognostic index (CLL-IPI), an established prognostic score. Herein, we continue to support our finding in additional HC MBLs and report the pooled results across the two cohorts. From the Mayo Clinic CLL Resource, we sequenced a total 167 HC MBL (112 from the initial round and 55 from additional sequencing). We extracted DNA from CD5+/CD19+ B-cells and sequenced the coding regions of 59 driver genes. Somatic mutations were called using MuTect2 in tumor-only mode. Germline variants were eliminated based on minor allele frequencies &amp;gt;0.01% and by those identified in public databases, unless present in known CLL mutation hotspots. After filtering, we computed the TML based on the number of genes with high impact (nonsense, frameshift and splicing) and hotspot mutations. Cox regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI), adjusted for sex and CLL-IPI. Stratified analyses were conducted by low/intermediate risk and high/very high CLL-IPI. Of the 167 HC MBL, low risk CLL-IPI comprised 60%, intermediate risk 28%, high risk 12%; and none were very-high risk. The most commonly mutated genes were SF3B1 (11%), NOTCH1 (9%), TP53 (7%), BIRC3 (7%), and MYD88 (6%); and 52 (31%) individuals had mutations in at least one gene. The median follow-up was 4.4 years, and 26 of the 167 individuals progressed to CLL requiring therapy. HC MBL with ≥2 mutated genes had a 28% 5-year risk of needing therapy compared to 6% among those with no mutated genes. Similar to our initial finding (HR=1.53, CI:1.12-2.07; P=0.007), we found a shorter TTT in the additional HC MBLs (HR=4.63, CI:1.57-13.7, P=0.006), and in the pooled cohort (HR=1.72; CI:1.29-2.28, P=0.0002). When we stratified by CLL-IPI risk, TML remained associated with TTT among individuals with low/intermediate CLL-IPI risk in the additional HC MBLs (HR=3.52, CI:1.11-11.2, P=0.03) and in the pooled cohort (HR=2.25, CI:1.34-3.77, P=0.002). A non-significant 2.8 fold association was observed with high risk CLL-IPI in the pooled cohort. In conclusion, the TML along with the CLL-IPI provide clinicians with a more accurate prognostic information regarding disease progression requiring therapy, especially for those MBLs with low to intermediate risk based on CLL-IPI. If validated, these findings may modify current practice guidelines for individuals with HC MBL. Citation Format: Geffen Kleinstern, Cecilia Bonolo de Campos, Nicholas J. Boddicker, Daniel R. O'Brien, Shulan Tian, Chantel Barney, Kari G. Rabe, Cristine Allmer, Laura Bruins, Aaron D. Norman, Timothy G. Call, Sameer A. Parikh, Jose F. Leis, Wei Ding, Huihuang Yan, James R. Cerhan, Neil E. Kay, Celine Vachon, Esteban Braggio, Susan L. Slager. Tumor mutational load derived from recurrently mutated genes in chronic lymphocytic leukemia (CLL) predicts time-to-first treatment in high-count monoclonal B-cell lymphocytosis (HC MBL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 884.

Hypogammaglobulinemia in Chronic Lymphocytic Leukemia: A Predictor of Outcome?

BACKGROUNDHypogammaglobulinemia (HYPO) is a typical feature of chronic lymphocytic leukemia (CLL), with an incidence of 20-60% at diagnosis and a relationship with infections occurrence. Predictive and prognostic factors are well known (IGHV, del11q, del17p, TP53); CLL-IPI score including age, clinical stage, beta2microglobulin, IGHV and deletion 17p and/or TP53 mutation has been recently validated. It identifies 4 risk groups with significantly different time to first treatment (TTFT) and overall survival (OS). Prognostic significance of HYPO at diagnosis has not been extensively evaluated in terms of OS and TTFT. Only IgG serum levels have been reported to be associated with TTFT but no data are available on other immunoglobulin classes (Ig).AIM To evaluate the impact of HYPO and single Ig classes on TTFT in a retrospective cohort of CLL patients and to assess the relationship between HYPO and CLL-IPI.METHODSWe retrospectively evaluated 698 consecutive CLL patients diagnosed at our Institution from 1983 till 2016. Data from laboratory, biological analysis and clinical stage were collected. We also evaluated immunoglobulin (Ig) status (i.e. IgG, IgM and IgA) at diagnosis and calculated CLL-IPI. HYPO was defined basing on our laboratory cut-offs (IgA 70 mg/dl, IgG 700 mg/dl, IgM 40 mg/dl). However, as no recognized prognostic/predictive Ig cut off has been reported to date, we aimed to identify a prognostic threshold for each Ig class.RESULTSFrom 698 patients assessed, 410 cases were evaluable for Ig values at diagnosis. IgA levels were lower than 70 mg/dl in 17,4%, IgG lower than 700 mg/dl in 22,2%, and IgM lower 40 mg/dl in 33.7%. Forty-six percent of patients presented deficit of at least one Ig class, while 7.8% of patients had all Ig low. Each Ig deficit was related with a shorter TTFT with the following hazard ratios (HRs): 2.09 (1.45-3.03) for IgA (P<0.0001), 1.58 (1.10-2.27) for IgG (P=0.008) and 1.52 (1.09-2.13) for IgM (P=0.01) (Figure 1, A-B-C). However, only IgA deficit maintains statistical significance in multivariate analysis [HR 1.59 (1.08-2.35)].A prognostic threshold for each Ig class was identified maximizing the differences in TTFT and the following values were obtained: 80 mg/dl for IgA, 410 mg/dl for IgG and 18 mg/dl for IgM (Figure 1, D-E-F).Considering CLL-IPI, 186 patients presented IPI 0-1, 99 had IPI 2-3, 32 patients IPI 4-6, and 12 patients had IPI 7-10. Even in our series, CLL-IPI separated four risk groups with different TTFT and OS, suggesting that our cohort may be suitable to evaluate new prognostic factors. As regards the relationship between HYPO and CLL-IPI, we observed a correlation with IgA levels, using our laboratory cut-off. Moreover, we found a relationship among CLL-IPI and both IgA and IgM values, when using the newly validated Ig cut-off. Finally, CLL-IPI was a stronger prognostic factor for TTFT than HYPO in our analysis. However, the addition of IgA deficit to CLL-IPI appears to further improve CLL prognostication.CONCLUSIONOur analysis supports the impact of HYPO on CLL prognosis. Although CLL-IPI has a stronger prognostic value for TTFT compared to HYPO, the inclusion of IgA deficit appears to further improve accuracy on CLL prognostication. [Display omitted] DisclosuresBarcellini:Alexion: Honoraria; Agios: Honoraria, Research Funding; Novartis: Honoraria.

Clinical and molecular characteristics and treatment patterns of adolescent and young adult patients with chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) rarely presents in adolescent and young adult (AYA) patients (patients aged 15-39years). Disease characteristics and outcomes of AYA patients with CLL are not well understood, particularly in the era of novel oral targeted therapies. We analysed outcomes of 227 AYA patients with CLL diagnosed in the last two decades and evaluated at our institution. Median time to first treatment (TTFT) was 2·2years, and five- and 10-year overall survival (OS) were 90% and 78%, respectively. Pre-treatment elevated beta 2-microglobulin, advanced Rai stage, del(11q) or del(17p) by FISH, unmutated IGHV and CD38 positivity were associated with both shorter TTFT and OS. Within the subgroup of patients who received oral targeted therapy at any time, del(11q) or del(17p) and complex karyotype were associated with shorter OS. First-line treatment choice was significantly associated with time to second treatment (P<0·001). Patients harbouring del(11q) or del(17p) experienced shorter time to Richter transformation and were more likely to undergo an allogeneic stem cell transplant. There was a significant association between age and both OS and time to Richter transformation. Our study is the first analysis of AYA patients with CLL with a large number of patients treated with oral targeted therapies.

Mutations of the Exportin 1 (XPO1) Gene Predict Shorter Time to First Treatment in 1092 Early Stage Chronic Lymphocytic Leukemia Patients. Α Training/Validation Study

Mutations of the Exportin 1 (XPO1) Gene Predict Shorter Time to First Treatment in 1092 Early Stage Chronic Lymphocytic Leukemia Patients. Α Training/Validation Study

The IGLV3-21R110 Defines a Subset of Chronic Lymphocytic Leukemia with Intermediate Epigenetic Subtype and Poor Outcome

Introduction: B-cell receptor (BCR) signaling is crucial for chronic lymphocytic leukemia (CLL) biology. IGLV3-21-expressing B-cells may acquire a single point mutation (R110) that triggers autonomous BCR signaling conferring aggressive behavior. Epigenetic studies have defined three CLL subtypes based on methylation signatures reminiscent of pre- and post-germinal center B-cells named naïve-like (n-CLL), intermediate (i-CLL) and memory-like CLL (m-CLL) with different biological features. i-CLL carry a borderline IGHV mutational load and a significant higher usage of IGHV3-21/IGLV3-21. The integration of these factors might translate into novel insights in CLL pathogenesis with implications on the proposed stratification of the patients. Aim: To determine the clinical and biological features of the IGLV3-21R110 in CLL in the light of the epigenetic subtypes and immunogenetic, genomic and transcriptomic landscapes of the tumors. Methods: We characterized the immunoglobulin (IG) gene of 584 CLL cases from whole-genome/exome and RNA sequencing using our recently developed algorithm IgCaller (Nadeu et al., Nat. Commun. 2020) and MiXCR, respectively. The genomic makeup of the tumors was obtained from whole-genome/exome sequencing while RNA sequencing data for 369 cases was used for gene expression analyses. Expression levels of WNT5A and WNT5B were verified by quantitative PCR with reverse transcriptase. Primary end points were time to first treatment (TTFT) and overall survival (OS) calculated from the date of diagnosis. All patients gave written informed consent. The study was approved by the Ethics Committee of the Hospital Clínic of Barcelona. Results: The IGLV3-21R110 was detected in 6.5% of cases being similarly distributed between mutated (6.5%) and unmutated (6.6%) IGHV cases (P=0.56). In contrast, the IGLV3-21R110 was found in 30/79 (38%) i-CLL compared to only 5/291 (1.7%) m-CLL and 1/189 (0.5%) n-CLL (P&amp;lt;0.001). All stereotyped subset #2 cases carried IGLV3-21R110 while 62% of IGLV3-21R110 i-CLL had non-stereotyped IG genes. IGLV3-21R110 i-CLL had a borderline IGHV mutational status (median 97.7%) that was higher than i-CLL lacking the IGLV3-21R110 (median 96.2%, P=0.005). IGLV3-21R110 i-CLL had significantly higher number of SF3B1 and ATM mutations, and total number of driver alterations. Nonetheless, the R110 mutation was the sole alteration in one i-CLL case and accompanied only by del(13q) in three. Although composite regarding IGHV mutational status, IGLV3-21R110 i-CLL transcriptomically resembled naïve-like/unmutated IGHV CLL and had a specific expression signature of 64 genes with overexpression of WNT5A and WNT5B as hallmarks. No differences were observed in the expression profile of subset #2 and non-subset #2 IGLV3-21R110 i-CLL tumors. On the other hand, i-CLL lacking the IGLV3-21R110 phenotypically mirrored memory-like/mutated IGHV cases. In relation to prognosis, IGLV3-21R110 i-CLL had a short TTFT and OS similar to n-CLL/unmutated IGHV cases whereas non-IGLV3-21R110 i-CLL had a good prognosis similar to memory-like/mutated IGHV. Therefore, i-CLL cases, which have been associated with an intermediate prognosis between m-CLL and n-CLL in previous studies, can be divided in two subgroups of cases with opposed clinical evolutions based on the IGLV3-21R110. Indeed, the IGLV3-21R110 and n-CLL subtype retained independent prognostic value in multivariate analyses while the i-CLL lost its prognostic prediction both for TTFT and OS. The prognostic value of the IGLV3-21R110 was also independent of the IGHV mutational status. In terms of applicability in the clinics, all n-CLL cases were classified as unmutated IGHV and 98% of m-CLL were mutated IGHV. Thus, either a complete IG characterization (IGHV mutational status and IGLV3-21R110) or the integration of the n-CLL subtype and IGLV3-21R110 identified virtually the same subset of patients with aggressive disease. Conclusions: The IGLV3-21R110 defines a CLL subset with borderline IGHV mutations, specific driver alterations, a gene expression signature including WNT5A/B overexpression, and an unfavorable prognosis independent of the IGHV mutational status and epigenetic subtypes. Our findings support the identification of IGLV3-21R110 CLL as a particular subgroup of the disease with relevance in the risk stratification of the patients. Disclosures Nadeu: Janssen: Honoraria. Campo:NIH: Consultancy, Other: Co-inventor on a patent related to the MCL35 assay filed at the National Institutes of Health, United States of America..

Effect of time to treatment and comprehensive care at commission on cancer-accredited practices on survival in rural patients with colorectal cancer.

109 Background: Rural cancer care in the United States has unique challenges from variable access to care. This study examined differences in time to first treatment (TTT), a surrogate for access, and predictors of overall survival (OS) between rural and non-rural colorectal cancer (CRC) patients. Methods: Patients with stage I-III CRC from 2004-2012 in the National Cancer Database of Commission on Cancer (CoC)-accredited facilities were included and categorized into rural and non-rural groups. Differences in demographic, disease characteristics, socioeconomic (SE) factors and TTT (&lt; 4 weeks, 4-8 weeks and &gt; 8 weeks) between rural and non-rural patients were assessed by Chi-square test. The effect of demographics, SE factors, and TTT on OS were assessed using Cox models. Results: The study population comprised 605,913, 11,649 (2%) of whom were rural. Compared to non-rural patients, rural patients were more likely to be age &gt; 65, male, Caucasian, receive care at non-academic centers, have government insurance, have lower income and less education (p&lt;0.0001 for all). Significant demographic and SE differences are shown in Table. Rural patients had similar mean TTT compared to non-rural patients (2.76 vs. 2.84 weeks, p = 0.35). Slightly more rural patients had TTT &lt; 4 weeks (77% vs. 75%, p &lt;0.0001). Shorter TTT (both &lt;4 weeks vs. 8 weeks and 4-8 weeks vs. &gt; 8 weeks) was associated with improved OS (HR: 0.87, 95% CI: 0.85-0.89, p&lt;0.0001 and HR: 0.74, 95% CI: 0.73-0.76, p&lt;0.0001, respectively). After adjusting for demographic, disease and SE factors, rural status was associated with modestly better OS compared to non-rural status (HR: 0.96, 95% CI: 0.92-0.99, p=0.006). Conclusions: Despite several adverse demographic and socioeconomic factors, rural CRC patients had modestly better OS compared to non-rural patients. Rural and non-rural CRC patients had similar TTT in this cohort. These data suggest the comprehensive cancer care delivered by CoC-accredited practices is associated with rapid TTT and improved OS in rural CRC patients. It is unclear whether our data apply to non-CoC-accredited facilities in rural United States. [Table: see text]

Effect of shorter time to treatment on survival in rural patients with breast cancer.

7027 Background: Rural cancer care in the United States has unique challenges from variable access to care. This study examined differences in time to first treatment (TTT), a potential surrogate for access, and predictors of overall survival (OS) between rural and non-rural patients with breast cancer. Methods: Women with stage I-III breast cancer from 2004-2012 in the National Cancer Database of Commission on Cancer (CoC)-accredited facilities were included and categorized as rural and non-rural. Differences in demographic, disease and treatment characteristics, socioeconomic factors and TTT (&lt; 4 weeks, 4-8 weeks and &gt; 8 weeks) between rural and non-rural patients were assessed by Chi-square test. The effect of age, insurance status, cancer center type, community median income, community % no high school, and TTT on OS were assessed using univariate and multivariate Cox models. Results: The study included 1,205,031 patients, 18,417 (2%) of whom were rural. Compared to non-rural patients, rural patients were more likely to be age &gt; 65, Caucasian, receive care at non-academic centers, have government insurance, have lower income and less education (p &lt; 0.0001 for all). Significant demographic and socioeconomic differences are shown in Table. Rural patients had shorter mean TTT (3.72 vs. 4.35 weeks, p &lt; 0.0001). More rural patients had TTT &lt; 4 weeks (67% vs. 57%) and &lt; 8 weeks (94% vs. 90%), p &lt; 0.0001 for both. Shorter TTT (both &lt; 4 weeks vs. 8 weeks and 4-8 weeks vs. &gt; 8 weeks) was associated with improved OS (HR: 0.84, 95% CI: 0.82-0.86, p &lt; 0.0001 and HR: 0.82, 95% CI: 0.81-0.83, p &lt; 0.0001, respectively). After adjusting for demographic, socioeconomic, disease stage and treatment factors, rural status was associated with significantly better OS compared to non-rural status (HR: 0.92, 95% CI: 0.89-0.96, p &lt; 0.0001). Conclusions: Despite several adverse socioeconomic factors, rural patients with breast cancer with access to CoC-accredited facilities had significantly shorter TTT and better OS compared to non-rural patients. These data suggest improving TTT can mitigate disparities in rural cancer care. It is unclear whether our data apply to non-CoC-accredited facilities in rural United States. [Table: see text]

Tumor mutational load predicts time to first treatment in chronic lymphocytic leukemia (CLL) and monoclonal B-cell lymphocytosis beyond the CLL international prognostic index.

Next-generation sequencing identified about 60 genes recurrently mutated in chronic lymphocytic leukemia (CLL). We examined the additive prognostic value of the total number of recurrently mutated CLL genes (i.e., tumor mutational load [TML]) or the individually mutated genes beyond the CLL international prognostic index (CLL-IPI) in newly diagnosed CLL and high-count monoclonal B-cell lymphocytosis (HC MBL). We sequenced 59 genes among 557 individuals (112 HC MBL/445 CLL) in a multi-stage design, to estimate hazard ratios (HR) and 95% confidence intervals (CI) for time-to-first treatment (TTT), adjusted for CLL-IPI and sex. TML was associated with shorter TTT in the discovery and validation cohorts, with a combined estimate of continuous HR = 1.27 (CI:1.17-1.39, P = 2.6 × 10-8 ; c-statistic = 0.76). When stratified by CLL-IPI, the association of TML with TTT was stronger and validated within low/intermediate risk (combined HR = 1.54, CI:1.37-1.72, P = 7.0 × 10-14 ). Overall, 80% of low/intermediate CLL-IPI cases with two or more mutated genes progressed to require therapy within 5 years, compared to 24% among those without mutations. TML was also associated with shorter TTT in the HC MBL cohort (HR = 1.53, CI:1.12-2.07, P = .007; c-statistic = 0.71). TML is a strong prognostic factor for TTT independent of CLL-IPI, especially among low/intermediate CLL-IPI risk, and a better predictor than any single gene. Mutational screening at early stages may improve risk stratification and better predict TTT.

The Number of Signaling Pathways Altered by Driver Mutations in Chronic Lymphocytic Leukemia Impacts Disease Outcome.

Investigation of signaling pathways altered by recurrent gene mutations and their clinical impact in a consecutive cohort of patients with newly diagnosed chronic lymphocytic leukemia (CLL). The heterogeneous clinical course and genetic complexity of CLL warrant improved molecular prognostication. However, the prognostic value of recurrent mutations at the time of diagnosis remains unclear. We sequenced samples from 314 consecutive, newly diagnosed patients with CLL to investigate the clinical impact of 56 recurrently mutated genes assessed by next-generation sequencing. Mutations were identified in 70% of patients with enrichment among IGHV unmutated cases. With 6.5 years of follow-up, 15 mutated genes investigated at the time of diagnosis demonstrated significant impact on time to first treatment (TTFT). Carrying driver mutations was associated with shorter TTFT and poor overall survival. For outcome from CLL diagnosis, the number of signaling pathways altered by driver mutations stratified patients better than the number of driver mutations. Moreover, we demonstrated gradual impact on TTFT with increasing number of altered pathways independent of CLL-IPI risk. Thus, a 25-gene, pathway-based biomarker assessing recurrent mutations refines prognostication in CLL, in particular for CLL-IPI low- and intermediate-risk patients. External validation emphasized that a broad gene panel including low burden mutations was key for the biomarker based on altered pathways. We propose to include the number of pathways altered by driver mutations as a biomarker together with CLL-IPI in prospective studies of CLL from time of diagnosis for incorporation into clinical care and personalized follow-up and treatment.

XPO1 Mutations May Identify Binet Α Chronic Lymphocytic Leukemia Patients with Shorter Time to First Treatment

Background. Chronic lymphocytic leukemia (CLL) is the most common leukemia of adults in western countries. CLL is a highly heterogeneous disease; some patients may never require treatment, whereas other relapse early after frontline therapy. In approximately 70% of newly diagnosed cases, CLL presents at an early clinical stage and is managed with a watch &amp; wait strategy. Until now, few clinical and molecular predictors inform on the risk of treatment requirement and the impact of CLL gene mutations is not completely understood. Purpose. We aimed at identifying new molecular markers that may predict early treatment requirement and may help clinicians to better plan the watch &amp; wait strategy in asymptomatic early stage CLL patients. Methods. This study includes 295 Binet A CLL patients referring at our institution who did not require treatment for at least 3 months after diagnosis. Tumor genomic DNA (gDNA) was isolated from peripheral blood mononuclear cells at the time of diagnosis. gDNA was analyzed in the coding exons plus splice sites of the most frequently mutated genes in CLL with a next-generation-sequencing (NGS) approach. NGS analysis was performed on the Illumina MiSeq instrument (coverage &gt;2000x in &gt;80% of the target region). The somatic function of VarScan2 was used for variant calling and a stringent bioinformatic pipeline was developed to protect against the false call of polymorphisms and sequencing errors. A threshold of 5% of variant allele frequency was set for variant calling. The primary endpoint was time to first treatment (TTFT) defined as the timeinterval between the date of CLL diagnosis and the date of first CLL treatment. Statistical analysis was performed using SPSS version 24.0. Results. The median age of the study cohort was 70.8 years old, 136 (46.1%) patients were female, 71 (24.1%) harbored unmutated IGHV genes, 44 (14.9%) had trisomy 12, 12 (4.1%) had 17p deletion, 15 (5.1%) had 11q deletion and 150 (50.8%) had 13q deletion. NGS mutational analysis showed that NOTCH1 was the most frequently mutated gene occurring in 25 (8.5%) patients, followed by ATM in 18 (6.1%), TP53 in 17 (5.8%), MYD88 in 12 (4.1%), SF3B1 in 10 (3.4%), XPO1 in 7 (2.4%), EGR2 in 6 (2.0%), NFKBIE in 4 (1.4%), POT1 in 2 (0.7%), and BIRC3 in 1 (0.3%) patients. After a median follow-up of 9.5 years, 80 (27.1%) patients required treatment. In univariate analysis, molecular characteristics associated with a shorter TTFT were trisomy 12 (HR: 2.42; 95% CI 1.43-4.15; p=0.001), unmutated IGHV genes (HR: 4.51; 95% CI 2.83-7.05; p&lt;0.0001) and mutations of XPO1 (HR: 8.88; 95% CI 3.77-20.95; p&lt;0.0001), NOTCH1 (HR: 3.02; 95% CI 1.66-5.51; p&lt;0.001) and SF3B1 (HR: 2.65; 95% CI 1.15-6.10; p=0.022). Interestingly, neither 17p deletion nor TP53 mutations associated with a shorter TTFT, in line with the notion that TP53 disruption interacts with treatment but not with a watch &amp; wait strategy. By multivariate analysis, XPO1 mutations (HR: 4.24; 95% CI 1.72-10.44; p=0.002) maintained an independent association with a shorter TTFT (Table 1). At 10 years, XPO1 mutated patients had a probability of remaining free from treatment of 0% compared to 69.3% for wild type cases (p&lt;0.0001) (Figure 1). Conclusions. Mutations of the XPO1 gene, encoding for exportin 1 which mediates the nuclear export of proteins and RNA, are an independent predictor of shorter TTFT and, if validated, might help clinicians in a better management of the watch &amp; wait strategy for Binet A CLL patients. Moreover, since most of mutations, approximately 90%, affect the glutamic acid in position 571, polymerase chain reaction based methods may be used to identify XPO1 mutations in a simple and time effective manner. Disclosures Rossi: Abbvie: Honoraria, Other: Scientific advisory board; Janseen: Honoraria, Other: Scientific advisory board; Roche: Honoraria, Other: Scientific advisory board; Astra Zeneca: Honoraria, Other: Scientific advisory board; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Gaidano:AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra-Zeneca: Consultancy, Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sunesys: Consultancy, Honoraria.