Slager, Susan L.

Abstract Background and Significance : Chronic lymphocytic leukemia (CLL) is the most heritable hematologic malignancy; however, no common CLL predisposition genes are known. Monoclonal B lymphocytosis (MBL) is a hematologic syndrome characterized by small accumulations of B lymphocytes in the peripheral blood. MBL has a CLL-like immunophenotype, may progress to overt CLL, and is over represented in CLL families. Therefore, MBL observed in the context of familial CLL may be a marker of inherited risk for development of CLL. Detailed characterization of family-associated MBL may also provide mechanistic insights into the pathogenesis of familial CLL. Our strategy was to detail the biologic characteristics of CLL in family-associated MBL. Methods : Persons with MBL were identified by flow cytometric screening of peripheral blood from unaffected members of CLL kindreds ascertained by Genetic Epidemiology of CLL Consortium (GEC) sites. Flow cytometry was used to determine the surface immunophenotype including CD38 and intracellular ZAP-70. We defined MBL as populations of CD19+, CD5+, CD20lo, CD23+ B cells that comprised at least 2% of the CD19+ peripheral B cell compartment and did not exceed 5.0 × 109 MBL cells/L. RNA and genomic DNA from single MBL cells isolated by flow cytometric sorting were analyzed using PCR to determine immunoglobulin heavy and light chain sequences. MBL cells were sorted in bulk for FISH for loci associated with clinical CLL. Results : Twenty-two out of 190 (12%) unaffected family members were found to have MBL. We observed significant variability in the size of the MBL clone as a percentage of the CD19+ B cell compartment (mean 32%; range 2%–97%). Nonetheless, the absolute size of the MBL clone was small, 15 of 17 individuals had < 200 × 106 MBL cells/L. CD38 expression (defined as CD38 surface expression in ≥30% of MBL cells) was observed in 8 of 18 subjects tested. ZAP-70 (defined as intracellular expression in ≥ 20% of MBL cells) was expressed in 4 of 12 participants. Among 12 subjects tested, 5 MBL expressed both surface IgD and IgM, 3 expressed IgD only, 2 expressed IgM only, and 2 did not express IgD or IgM. Analysis of immunoglobulin heavy and light chains has been completed in 8 individuals. Both immunoglobulin heavy chain variable (IgVH) region mutated (n = 12) and unmutated (n = 4) sequences were observed. Four of 8 individuals had 2 or more unrelated MBL clones (range 2–5), including one individual with both unmutated and mutated clones. Among the 16 MBL clones identified in these 8 subjects, VH3 or VH4 rearrangements were observed in all MBL clones. The most commonly rearranged IgVH genes were 3–07 (3 MBL clones), 3–15 (3), and 4–34 (3). No VH1 family gene rearrangements were observed. In one individual, a VH3–07 MBL clone showed intraclonal diversification suggestive of antigen driven immunoglobulin sequence changes. Twenty productive light chain rearrangements were identified among the 16 MBL clones, with 11 Vλ and 9 Vκ genes used. We observed 6 productive rearrangements of Vλ1–51. MBL cells were bulk sorted for FISH from 9 subjects. Mono or biallelic deletion of 13q14.3 was observed in 5 subjects, the other 4 were normal. Conclusions : Our findings confirm that MBL is commonly observed among the unaffected family members from CLL kindreds. We found that some MBL clones express ZAP-70, CD38 or have unmutated IgVH genes and thus are similar to clinical CLL. The clinical outcome of these MBL clones in relation to our baseline prognostic characterization will be of interest. Small MBL clones are commonly oligoclonal. Importantly, although the immunoglobulin heavy and light chain genes rearranged in these MBL clones are all commonly used in CLL, the absence of VH1 and abundance of Vλ1–51 rearrangements do suggests differences in BCR usage between CLL and MBL. Further investigation of family associated MBL may clarify the genetics and immunobiology of familial CLL.

Abstract Background: Recent literature suggests that statins may have anticancer potential. This effect is thought to be mediated through 2 primary mechanisms - impairment of protein prenylation and interference with the formation of cholesterol-rich lipid microdomains, or “lipid rafts” within the cell membrane. Both of these processes are critical for signaling activity of numerous proteins important for lymphomagenesis and tumor survival. Recent data, however, suggest that statin use may directly inhibit rituximab binding to CD20 and therefore rituximab efficacy. These findings raised significant concerns about statin use during rituximab treatment. Here we report on statin use and clinical outcome in a cohort of FL and DLBCL treated patients, most of whom were treated with rituximab containing regimens. Methods: 293 newly diagnosed FL patients and 228 newly diagnosed DLBCL patients were prospectively enrolled in our Lymphoma SPORE registry from 9/2002 through 6/2007. Pathology was centrally reviewed. All patients were followed for retreatment, progression-free and overall survival. Statin use at the time of diagnosis and time of initial treatment was abstracted from the medical record. An event was defined by disease progression, retreatment, or death due to any cause. Results: 19% of FL patients and 22% of DLBCL patients were on statins at diagnosis; 16% and 19% were on statins during treatment, respectively. Initial therapy for the FL patients was observation (40%), R-CHOP (19%), R-CVP (12%), rituximab alone (8%), CVP (7%), RT (6%), and other (8%). All DLBCL patients received rituximab with CHOP or a CHOP-like regimen. At a median follow-up of 36 months (range 3–73), 109 (37%) and 65 (29%) of FL and DLBCL patients had an event; 19 (6%) and 46 (20%) of FL and DLBCL patients died, respectively. After adjusting for FLIPI, grade, and initial therapy type, statin use at diagnosis was associated with better event-free survival (HR = 0.57, 95% CI: 0.34–0.95, p=0.03) in FL patients. Statin use during treatment in FL patients was also associated with better event-free survival, though not statistically significant (HR = 0.67, 95% CI: 0.39–1.16, p=0.15). The improvement in EFS for FL patients was consistent across initial therapies, including observation. Statin use was not associated with IPI-adjusted overall survival or event-free survival in DLBCL (all p > 0.50). Conclusions: Statin therapy does not appear to be associated with inferior clinical outcome in DLBCL treated with rituximab and CHOP or CHOP-like therapy. Therefore direct inhibition of rituximab binding to CD20 may have limited clinical significance or/and may be overcome by inhibitory impact of statins on cell signaling. The latter possibility is supported by our observation that statin use is associated with improved event-free survival in follicular lymphoma. Figure Figure Figure Figure

Abstract Background: Inhibitors of HMG-CoA reductase (“statins”) are effective in reducing the risk of cardiovascular disease. Preclinical data from rodents suggested that they may increase the incidence of some cancers, including lymphoma. However, monitoring of randomized trials in humans have generally found decreased cancer risks, and these findings have been supported by a growing number of observational studies, including three recent reports of a protective association in NHL. The suggested anti-carcinogenic mechanisms for statins include their impact on inflammatory (including a shift from a Th1 to Th2 profile) and angiogenesis pathways, as well as the induction of apoptosis by modulation of signaling pathways, all of which are of biologic relevance in NHL. Methods: We evaluated the history of statin use and risk of NHL in a clinic-based study of 243 newly diagnosed NHL cases and 499 frequency matched controls enrolled at the Mayo Clinic from 2002-2005. Risk factor data were collected using self-administered questionnaires, and included history of use of cholesterol lowering drugs two or more years before diagnosis (for cases) or enrollment (for controls); specific drug names were not available. Unconditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (CI), adjusting for age, gender, and residence. NHL subtypes were centrally reviewed, and subtype-specific risks were estimated using polychotomous logistic regression. Results. The mean age at diagnosis was 59.5 years for cases and 55% were men; among controls, the mean age at enrollment was 61.8 years and 54% were men. Twenty-one percent of the cases reported ever using statins compared to 30% of the controls, supporting a lower risk of NHL for ever users (OR=0.69; 95% CI 0.47–1.00). The lowest risk was seen for the longest users; i.e., compared to never users, person who had 10 or more years of use had the greatest reduction in risk (OR=0.52; 95% CI 0.24–1.10). A history of high cholesterol was also inversely associated with risk of NHL (OR=0.72; 95% CI 0.55–0.93). However, the association for the type of treatment for cholesterol lowering varied. Those who were medically treated had inverse association with risk of NHL (OR=0.63; 95% CI 0.46–0.86), while the no treatment and dietary change only groups were found to have no association with risk. The reduction in NHL risk with medical treatment was specific to statin use, as the use of other cholesterol lowering drugs was not associated with risk (OR=1.13; 95% CI 0.50–2.57). These results were not confounded by education, family history of NHL, body mass index, cigarette smoking or alcohol use. In subtype analysis, the inverse association was seen for diffuse large B-cell lymphoma (OR=0.27; 95% CI 0.08–0.90), but not for CLL/SLL or follicular NHL. Conclusions. Statin use was associated with a lower risk of developing NHL, particular diffuse large B-Cell lymphoma.

Abstract BACKGROUND: The diagnosis of monoclonal B-cell lymphocytosis (MBL) is used to characterize patients who have a circulating population of clonal B-cells, a total B-cell count of <5 x 109/L, and no other features of another B-cell lymphoproliferative disorder. In most patients the immunophenotype is similar to that of chronic lymphocytic leukemia with co-expression of CD19 and CD5. The natural history of CLL-phenotype MBL is unclear. We used the Mayo Clinic hematopathology database to identify patients with CLL-phenotype MBL and abstracted clinical information on natural history and prognostic parameters from clinical and research records. METHODS: Using hematopathology records, we identified a cohort of 1820 patients seen at Mayo Clinic between August 1998 and May 2006 who underwent investigation using peripheral blood flow cytometry and who were found to have a clonal B-cell population of CLL phenotype. After elimination of patients with advanced stage (Rai I-IV), previously treated CLL, and individuals with an established diagnosis of CLL/MBL >1 year prior to flow, 636 unique patients with isolated lymphocytosis were identified. Based on our prior analysis (Leukemia Research 32:1458) demonstrating that nearly all patients with an ALC >10x109/L have a B-cell count >5x109/L, we focused the remaining analysis on the 405/636 patients who had an ALC <10x109/L and the necessary raw data from flow cytometry analysis to determine the B-cell count. RESULTS: Among the 405 individuals with an ALC <10x109/L, 306 (76%) had a B-cell count <5x109/L at the time of flow and met the current criteria for the diagnosis of MBL (BJH 130:325). Median age at the time of MBL diagnosis was 70 years (range 34 – 93). A slight male preponderance was observed (59% male). B-cell counts ranged from 0.02 to 4.99x109/L and ALC ranged from 0.3–9.6 x109/L. CD38 status was available for 268 (88%) MBL patients of whom 20% were CD38 positive using the 30% threshold. Cytogenetic analysis by fluorescent in situ hybridization (FISH) was available in 130 (42%) MBL patients. Using the hierarchical classification system of Dohner and colleagues, 57 (44%) were 13q-, 23 (18%) were trisomy 12, 5 (4%) were 11q-, 4 (3%) were 17p-, and 39 (30%) had no defect detected. ZAP-70 status was available for 77 (25%) patients of whom 13% were ZAP-70+ positive. Patients underwent sequential monitoring with a median follow-up of 1.7 yrs (range 0–8.1 yrs). Time from diagnosis to treatment for patients meeting criteria for MBL (n=306) as compared to Rai stage 0 CLL patients with B-cell counts between 5.0 and 10.0 x109/L (n=99) was not significantly different and is shown in Figure 1 (p=0.87). For individuals with MBL, survival free of treatment was 98% (95%CI: 96–100%) at 1 year, 93% (95%CI: 89–98%) at 2 years, and 77% (95%CI: 67–89%) at 5 years. While gender (p=0.10), and B-cell count as a continuous variable (p=0.15) were not found to be associated with time to treatment (TTT) among MBL patients, age (p=0.02, HR=0.94, 95% CI: 0.89–0.99) and CD38 status (p<0.02, HR: 3.3, 95% CI: 1.2–9.2) did show a relationship with TTT. CONCLUSIONS: Although we observed a low rate of progression among individuals meeting criteria for MBL, TFS was similar to individuals meeting current criteria for Rai stage 0 CLL who had B-cell counts between 5.0 – 10.0 x109/L . Among individuals meeting criteria for MBL, younger patients and those who were CD38 positive had a shorter time to treatment. Additional studies are needed to determine what B-cell count or other characteristics should be used to distinguish between MBL and Rai stage 0 CLL. FIGURE: FIGURE:.

Abstract BACKGROUND: The diagnosis of CLL among asymptomatic patients without lymphadenopathy or cytopenias has historically been based on documenting a characteristic lymphocyte clone and the presence of lymphocytosis. Currently, there are no data regarding what lymphocyte type (absolute lymphocyte count [ALC] or B-cell count) or threshold should be used for this diagnosis. We analyzed the relationship of these lymphocyte counts to clinical outcome in a cohort of 459 patients to determine whether the CLL diagnosis: should be based on ALC or B-cell count what lymphocyte threshold should be used for diagnosis whether any lymphocyte counts has independent prognostic value after accounting for molecular prognostic markers. METHODS: We used the Mayo Clinic CLL database to identify all Rai stage 0 patients diagnosed with CLL between 1/1/00 and 12/31/07 who were evaluated and had flow cytometry at Mayo within 12 months of diagnosis. All patients had lymphocytosis (ALC ≥5 x 109/L) and fulfilled the 1996 criteria for CLL. Raw data from the peripheral blood flow analysis was used in conjunction with blood counts to determine ALC and absolute B-cell count at diagnosis. Estimates of survival were calculated using the Kaplan-Meier method. RESULTS: To assess whether B-cell count or ALC more strongly related to clinical outcome, we evaluated the relationship of these variables with treatment free survival (TFS) and overall survival (OS; n=459). When treated as continuous variables (i.e. measuring risk of each 1.0 x 109/L increase in cell count), both ALC and B-cell count were related to TFS (hazard ratio [HR] ALC=1.02; p<0.0001; HR B-cell count=1.02; p<0.0001) and OS (HR ALC=1.02; p=0.04; HR B-cell count=1.02; p=0.02). Because B-cell count and ALC related to TFS and OS as a continuous variables, we next evaluated what threshold (nearest 1.0 x109/L) at diagnosis best related to an individual’s risk of requiring chemotherapeutic treatment and/or dying of CLL using the HR (log rank statistic) and c-statistic [c=1 indicates perfect discrimination between poor survivors and good survivors; c=0.5 equivalent to chance]. The B-cell threshold that best predicted OS was 11 x 109/L (HR=2.36, p=0.01; c=0.60). This threshold also predicted TFS (HR=3.02; p<0.0001; c=0.64). With respect to ALC, a threshold of 12 x 109/L was able to predict TFS (HR=2.28, p=0.003; c=0.62) but not OS (HR=1.62, p=0.12; c=0.56). The B-cell threshold used in the current diagnostic criteria (5 x 109/L) was able to predict TFS (HR=3.24, p<0.0001; c=0.63), but not OS (HR=1.64, p=0.13; c=0.55) Finally, we evaluated the ability of B-cell count to predict TFS independent of IGHV mutation status, ZAP-70 status, CD38 status, and FISH. Since not all patients had all prognostic tests performed, the predictive value of B-cell count (< or ≥11 x 109) independent of the other prognostic variable was assessed for each variable independently. B-cell count retained prognostic value independent of IGHV mutation status, ZAP-70 status, CD38 status, and FISH (all p≤0.001) [Table]. CONCLUSIONS: Although B-cell count and ALC have similar ability to predict TFS and OS as continuous variables, B-cell count may be a better predictor of TFS and OS when a defined lymphocyte threshold is used. These findings provide evidence to justify the recent proposal by Hallek et al (Blood 111:5446) to base the diagnosis of CLL on B-cell count rather than ALC. The results also provide justification for retaining the size of the B-cell count as part of the diagnostic criteria even in the era of molecular/biologic prognostic markers, but imply a threshold of 11 x 109 is the B-cell count that best predicts patient’s TFS and risk of death. Differentiating between CLL and MBL based on a patient’s likelihood of developing clinical symptoms and dying of disease could minimize unnecessary psychologic distress caused by labeling asymptomatic individuals at low risk for adverse clinical consequences as having leukemia. TABLE: TREATMENT FREE SURVIVAL HR p-value CD38 + 3.20 0.0002 B-cell ≥11 3.10 0.0001 ZAP + 8.33 < 0.0001 B-cell ≥11 6.86 < 0.0001 Unmutated 5.26 < 0.0001 B-cell ≥11 3.06 0.001 FISH (17p- or 11q-) 3.97 0.01 B-cell ≥11 3.67 < 0.0001

Abstract Background: The biology, pathology and clinical course of CD5+ chronic B cell lymphoproliferative disorders (CD5+ B-CLPD) excluding chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) and mantle cell lymphoma (MCL) are poorly defined. These patients could either have a leukemic variant of a known B cell malignancy or a novel disease entity. Objective: To define the clinical features and pathology of CD5+ B-CLPD, compare these features to CLL, and test the hypothesis that at least some of these patients have a unique B cell malignancy. Methods: The study was conducted with Institutional Review Board permission. We studied 231 patients evaluated in the Division of Hematology at Mayo Clinic Rochester between 1996 and 2008 who had CD5+ monoclonal B cell population in the peripheral blood and/or bone marrow, and in whom CLL and MCL was not diagnosed after flow cytometry, histology and interphase fluorescence in situ hybridization (FISH) examinations. Data were abstracted from patient records and from the Mayo Clinic CLL database. Statistical analysis: To compare differences in characteristics between CD5+ and CLL patients, χ2 statistics were used for qualitative variables (gender, treatment, vital status) and t-tests were used for quantitative variables (age). We performed survival and time to treatment analyses with results displayed using Kaplan-Meier curves and p-values calculated using a log-rank test. Results: We analyzed data on 231 CD5+ B-CLPD patients diagnosed between 7/1/1976 and 5/2/2008 and 1572 CLL patients diagnosed in the same time period. Median follow-up from diagnosis was 2.5 years (range 0 to 25.1 years) for the CD5+ patients and 5.2 years (range 0 to 29.9 years) for CLL patients. CD5+ B-CLPD patients had a median age at diagnosis of 68 years (range 30–94 years) with male predominance (61.5%). One hundred and nine of 231 (52.4%) patients received treatment for their CD5+ B-CLPD and 162 (70.1%) patients were alive at the time of last follow-up. As a group, CD5+ B-CLPD patients had a similar male predominance to CLL but were older at diagnosis. CD5+ B-CLPD patients required their first treatment significantly sooner than CLL patients (median 2.0 years vs. 6.8 years, (p< 0.001) and a higher percentage of CD5+ B-CLPD patients required treatment (52.4% vs. 37.5%, p<0.0001). In addition, CD5+ B-CLPD patients had a shorter survival from diagnosis than CLL patients (median 8.4 years vs. 12.5 years, p<0.001). In 60 patients the CD5+ B-CLPD disease was the leukemic phase of a known lymphoma (lymphoplasmacytic lymphoma, n=34; nodal marginal zone lymphoma, n=6; splenic marginal zone lymphoma, n=16; MALT lymphoma, n=4), 46 patients had incomplete data, and 125 patients did not have pathological and flow cytometry features of a known lymphoid malignancy. Next we compared clinical outcome among the 125 patients with unclassifiable CD5+ B-CLPD to the CLL patients. The unclassifiable CD5+B-CLPD patients were older at diagnosis (median 69 vs. 65 years, p=0.0003) but there were no significant differences in time to treatment (median 9.0 years vs. 6.8 years, p=0.93) or the proportion of patients receiving treatment (30% vs. 37.5%, p=0.11). The survival from diagnosis was shorter for unclassifiable CD5+ B-CLPD patients (median 6.3 vs. 12.5 years, p<0.001). Conclusions: In this large series of CD5+ B-CLPD patients we found that a large subset did not meet diagnostic criteria for known B-cell malignancies and could have a novel disease. This will need to be investigated further. We reviewed the pathology of all available archived tissue and intend to examine additional clinical and prognostic information including molecular prognostic markers. Our data provide a clinical rationale for the careful differentiation between patients with CLL and CD5+ B-CLPD.

Abstract 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.

Abstract To study the impact of dose modification and temporary interruption of ibrutinib in routine clinical practice, we conducted a retrospective study of consecutive CLL patients treated with ibrutinib outside the context of a clinical trial at Mayo Clinic, (Rochester, MN) from 11/2013 to 12/2017. Of 209 patients, 131 (74%) had unmutated IGHV , 38 (20%) had TP53 disruption, and 47 (22%) were previously untreated. A total of 87/209 (42%) patients started reduced dose ibrutinib (<420 mg daily; n = 43, physician preference; n = 33, concomitant medications; and n = 11, other). During 281 person‐years of treatment, 91/209 patients had temporary dose interruption (54%, nonhematologic toxicity; 29%, surgical procedures; 10%, hematologic toxicity; and 7%, other). After a median follow‐up of 24 months, the estimated median event‐free survival (EFS) was 36 months, and median overall survival (OS) was not reached. On multivariable analyses, temporary ibrutinib interruption (hazard ratio [HR]: 2.37, P = .006) and TP53 disruption at ibrutinib initiation (HR: 1.81, P = .048) were associated with shorter EFS, whereas only TP53 disruption (HR: 2.38, P = .015) was associated with shorter OS. Initial ibrutinib dose and dose modification during therapy did not appear to impact EFS or OS. These findings illustrate the challenges associated with continuous oral therapy with ibrutinib in patients with CLL.

7525 Background: New prognostic markers in chronic lymphocytic leukemia (CLL) are in demand. Different groups have developed models which combine multiple prognostic markers into a single index to classify CLL patients (pts). The CLL-International Prognostic Index (CLL-IPI) combines five parameters: age, clinical stage, TP53 status, IGHV mutational status, and serum β2 microglobulin levels. B-cell maturation antigen (BCMA) is a cell membrane receptor expressed exclusively on late stage B-cells and plasma cells with elevated serum (s) levels found in B-cell malignancies, such as multiple myeloma (MM). In MM, sBCMA levels can be used to monitor disease status and predict overall survival (OS). To further evaluate this biomarker in other hematologic malignancies, we studied it in CLL. Methods: Untreated (UNTX) CLL pts seen and consented at Mayo Clinic were identified. sBCMA levels were measured on stored sera of 331 UNTX CLL pts using an ELISA-based assay with a polyclonal anti-BCMA antibody from R&D Systems (Minneapolis, MN). The Mann-Whitney analysis was used to assess differences between CLL pts and healthy controls. The relationships between sBCMA and both time to first treatment (TFT) and OS were also assessed using Cox Regression models with an optimal sBCMA cutoff of 40.9 ng/mL. Results: The median age of pts was 61 years, and 71% were male. The distribution of CLL-IPI risk groups was as follows: 135 (41%) Low; 114 (34%) Intermediate; 67 (20%) High; 15 (5%) Very High. The median level of sBCMA in CLL pts (48.6 ng/mL) was higher (P <0.0001) than those of healthy controls (n = 104; 36.03 ng/mL). In CLL pts, sBCMA is significant in univariable analyses of TFT (HR 2.9 (95%CI, 2.0-4.2); P < 0.0001) and OS (HR 2.5 (95%CI, 1.5-4.0); P < 0.0003), and remains significant when adjusting for sex and CLL-IPI factors (HR 2.3 (95%CI, 1.6-3.3), P < 0.0001; HR 1.9 (95%CI 1.1-3.1), P = 0.01, respectively). Conclusions: sBCMA is elevated in CLL pts compared to healthy controls. After adjusting for CLL-IPI and sex, sBCMA levels provided independent prognostic value in predicting TFT and OS in this cohort. Measuring sBCMA with a readily accessible ELISA-based test, provides incremental value over the current CLL-IPI model in predicting prognosis of CLL.

7522 Background: Ibrutinib therapy is associated with an increased risk (~15%) of AF. An accurate risk assessment model for the development of AF in pts starting ibrutinib is not established, and outcomes after AF are not well described. Methods: An IRB approved retrospective review of CLL pts treated with ibrutinib at Mayo Clinic between Oct 2012 and Nov 2018 was conducted. Results: 299 pts were identified with a total of 565 years of ibrutinib exposure (Table). After a median follow-up of 24 months (range 0–70 months), 51 pts developed treatment-emergent AF (13 [25%] CTCAE 3 or higher). Our study assessed 3 clinical prediction models, the Framingham (Schanbel:Lancet 2009), Italian (Visentin:Blood 2018;132:3118), and Shanafelt (Shanafelt:Leuk Lymp; 2017) risk scores. Based on a lower Akaike information criteria, the Italian score was best able to predict risk of treatment emergent AF (2-year risk of AF with score 0 6%; 1-2 8%; 3-4 26%; 5+ 47%). Thirty (61%) pts were treated with medical therapy for AF (27 rate control; 2 rhythm control; 1 both). 16 (31%) pts underwent interventional therapy (3 AV node ablation; 11 cardioversion; and 2 pacemaker). Twelve (23%) pts temporarily held ibrutinib and resumed their original dose, 22 (43%) pts continued reduced dose ibrutinib and 11 (22%) continued their initial ibrutinib dose. Six (12%) pts permanently discontinued ibrutinib. Of 51 pts with treatment-emergent AF, 41 (80%) had a CHA2DS2-VASc score of ≥2 (41% received anticoagulation alone; 12% received antiplatelet therapy alone; 10% received both). No pt developed a thrombotic stroke after treatment-emergent AF. Two major bleeds, (1 GI and 1 intracranial) occurred, one in a pt on concomitant antiplatelet and anticoagulation therapy, and one in a pt receiving neither. The development of AF was associated with shorter event-free survival (HR 2.5, 95%CI 1.5-4.2, p<.001) and shorter overall survival (HR 3.5, 95%CI 2.0-6.3, p<.001). Conclusions: The Italian score was the best predictor of AF development in this cohort of ibrutinib treated pts. Although the vast majority of pts who develop AF after ibrutinib are able to continue therapy, the occurrence of AF appears to be associated with shorter EFS and OS. [Table: see text]