Abeykoon, Jithma P.

SummaryPatients with asymptomatic/smouldering Waldenström macroglobulinaemia (SWM) have a variable risk of progression to active WM. Our study evaluated 143 patients with SWM consecutively seen between January 1996 and December 2013. With a median [95% confidence interval (CI)] follow‐up of 9·5 [8·1–11·5] years, the cumulative rate of progression was 11% at 1 year, 38% at 3 years and 55% at 5 years. On multivariate analysis, haemoglobin (Hb) ≤123 g/l [risk ratio (RR) 2·08; P = 0·009] and β2‐microglobulin (β2M) ≥2·7 µg/ml (RR 2·0; P = 0·01) were independent predictors of a shorter time‐to‐progression (TTP) to active WM. Patients with myeloid differentiation factor 88 wild type (MYD88WT) genotype (n = 11) demonstrated a trend toward shorter TTP [median (95% CI) 1·7 (0·7–8·7) vs. 4·7 (2·4–7·7) years for the MYD88L265P cohort, n = 42; P = 0·11]. The presence of C‐X‐C chemokine receptor type 4 (CXCR4) mutation (n = 29) did not impact the TTP (median: 3 years for CXCR4WT vs. 5·6 years for CXCR4MUT, P = 0·34). The overall survival (OS) for patients with SWM (median: 18·1 years) was comparable to an age‐, sex‐ and calendar year‐matched USA population (median: 20·3 years, P = 0·502). In conclusion, Hb and β2M at diagnosis represent independent predictors of progression to active WM. Comparable survival of SWM and a matched USA population argues against pre‐emptive intervention in this patient population.

AbstractBackgroundDespite the unprecedented success of ibrutinib in lymphoma therapy, the development of ibrutinib resistance due to acquired BTK or PLCγ2 mutations has become a new clinical problem. However, not all resistance is mediated by these mutations and these mechanisms are poorly understood due to a lack of study tools that truly recapitulate this clinical scenario.MethodsWe established a novel patient‐derived ibrutinib‐resistant mantle cell lymphoma (MCL) line named MCIR1. Using immunological, molecular, and cytogenetic approaches, we comprehensively characterized MCIR1 and further demonstrated its utility in the study of resistance mechanisms and treatments to overcome this resistance.ResultsWe show that MCIR1 is a bona fide ibrutinib‐resistant MCL cell line with normal BTK‐/PLCγ2 but ibrutinib‐resistant ERK1/2 and AKT1 signaling. RNA‐Seq analysis revealed a robust non‐canonical NF‐kB signaling that drives the ibrutinib resistance. We also demonstrate the potential utility of a MCIR1‐based cell and mouse model for the discovery of new treatments to overcome BTK inhibitor resistance.ConclusionsWe have established the first patient‐derived ibrutinib‐resistant MCL cell line MCIR1 that lacks BTK or PLCγ2 mutations but exhibits a hyperactive non‐canonical NF‐kB pathway. We further demonstrate its utility in the discovery and validation of new drugs to overcome this resistance.

PURPOSE: The benefit of routine pre-emptive screening for severe acute respiratory syndrome coronavirus 2 infections in patients with cancer before cancer-directed therapies is unclear. Herein, we characterize the outcomes of a cohort of patients with cancer who were diagnosed with COVID-19 by routine screening (RS) in comparison with those diagnosed on the basis of clinical suspicion or exposure history (nonroutine screening [NRS]). METHODS: A multisite prospective observational study was conducted at three major and five satellite campuses of the Mayo Clinic Cancer Center between March 18 and July 31, 2020. The primary outcome was COVID-19–related hospital admission. Secondary outcomes included intensive care unit admissions and all-cause mortality. RESULTS: Five thousand four hundred fifty-two patients underwent RS in the outpatient setting only, and 44 (0.81%) were diagnosed with COVID-19. RS detected 19 additional patients from the scheduled inpatient admissions for surgical or interventional procedures or inpatient chemotherapy. One hundred sixty-one patients were diagnosed with COVID-19 on the basis of NRS. COVID-19–related hospitalization rate (17.5% v 26.7%; P = .14), intensive care unit admission (1.6% v 5.6%; P = .19), and mortality (4.8% v 3.7%; P = .72) were not significantly different between the RS and NRS groups. In the multivariable analysis, age ≥ 60 years (odds ratio, 4.4; P = .023) and an absolute lymphocyte count ≤ 1.4 × 109/L (odds ratio, 9.2; P = .002) were independent predictors of COVID-19–related hospital admission. CONCLUSION: The COVID-19 positivity rate was low on the basis of RS. Comparing the hospital admission and mortality outcomes with the NRS cohort, there were no significant differences. The value of routine pre-emptive screening of asymptomatic patients with cancer for COVID-19 remains low.

8049 Background: The treatment paradigm of Waldenström macroglobulinemia (WM) continues to evolve as new therapies expand our options for this indolent and incurable disease. While more profound responses are generally associated with longer treatment-free intervals, the impact of depth of response from fixed duration therapy in WM patients' survival needs further evaluation. In this international, multicenter cohort study, we report the prognostic impact of depth of response in WM. Methods: 319 WM patients treated with frontline fixed duration therapy [Dexamethasone/Rituximab/Cyclophosphamide (DRC), Bendamustine/Rituximab (BR), or Bortezomib/Dexamethasone/Rituximab (BDR)] were included. Response at the completion of therapy (6 months) was used in a landmark analysis for progression-free survival (PFS), time to next treatment (TTNT), and overall survival (OS) (defined as time from 6 months post treatment response to event or censor). Response was defined by modified IWWM-6 criteria. Associations between clinical variables and outcomes were evaluated using Cox proportional-hazard models. Results: The median age at the time of treatment initiation was 64 years (range: 29-94), 59% were men, and risk category by International Prognostic Scoring System (IPSS)-WM was low (n=67, 23%), intermediate (n=83, 29%), and high-risk (n=141, 48%). Evaluable responses at 6 months from frontline therapy [DRC (n=105; 41%), BR (n=83; 32%), BDR (n=68; 27%)] were available in 256 patients and included in the landmark analysis. Median follow-up was 63 months (95% CI: 59-70). The rate of major response (PR or better) at 6 months was 74% for the entire cohort. Five-year PFS rates from completion of therapy for patients who attained major response vs. those who did not were 71% and 43%, respectively (p<0.001). Five-year TTNT rates for patients who attained major response vs. not were 84% and 54%, respectively (p<0.001). Five-year OS rates for patients who attained major response vs. not were 92% and 77%, respectively (p<0.001). In multivariable analyses including other WM prognostic factors evaluated at initiation of frontline therapy, attaining a major response at 6 months was associated with superior PFS (HR 0.33, p<0.001), TTNT (HR 0.23, p<0.001), and OS (HR 0.31, p=0.001–Table). Conclusions: Achieving a major response at 6 months after frontline chemoimmunotherapy emerges as a significant prognostic factor for PFS, TTNT and OS in patients with WM.[Table: see text]

7050 Background: Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm manifesting as unifocal, multifocal, multisystem (MS) or pulmonary LCH (smoking-related). In pediatric LCH, somatic BRAFV600E prevalence is reported at 55-70%, and associated with increased risk of multisystem disease and early treatment failure. Our aim was to describe the prevalence of BRAFV600E mutation and evaluate its association with clinical manifestations and outcomes in adults with LCH. Methods: A retrospective review of adult patients diagnosed with LCH consecutively seen at Mayo Clinic from 2011 to 2020 was performed.Evaluation of association of BRAFV600E mutational status and clinical factors was conducted by the Chi-square test for independence. Progression-free survival (PFS) and overall survival (OS) were analyzed via the Kaplan Meier method and compared with the log-rank test to assess the effect of BRAFV600E. Results: Of the total LCH cohort ( n= 128), 88 patients with available BRAFV600E results were included in the study. Median age at diagnosis was 41y (range 19 - 88); 52.3% were male. 40 (45.5%) patients had a BRAFV600E mutation. Increasing age was associated with BRAFV600E (10-year increase OR 1.42, 95%CI 1.07-1.89; p= 0.017). No correlation was observed between BRAFV600E status and site of disease, risk organ (RO: liver, spleen, marrow) involvement, or MS disease. Patients with BRAFV600E were 4 times more likely to receive targeted therapy ( BRAF inhibitor) than non- BRAFV600E patients ( p= 0.018). After a median follow up of 46 mo (95% CI 30.8-61.2), PFS was similar between BRAFV600E and non- BRAFV600E patients ( p= 0.167). However, patients with BRAFV600E had a worse 3-year OS compared with non- BRAFV600E patients (84% vs. 97.1%, p= 0.027). Patients who died had a significantly higher age at LCH diagnosis (median 62 vs. 38 years; p= 0.0002). Conclusions: In our cohort of adults with LCH, BRAFV600E was less frequent than reported in pediatric literature and was associated with worse OS. The frequency of BRAFV600E was positively correlated with increasing age. Contrary to reports in pediatric LCH, there were no significant associations between BRAFV600E and high-risk or multisystem disease.[Table: see text]

6539 Background: The impact of insurance status on survival in diffuse large B‐cell lymphoma (DLBCL), the most common aggressive lymphoma, has not been evaluated after the implementation of the Affordable Care Act (ACA). The aim of this study is to compare overall survival (OS) in patients across insurance status groups and in the periods before and after the ACA. Methods: Adult patients with newly diagnosed DLBCL were identified from the National Cancer Database. The analysis was restricted to patients 64 years of age or younger as most patients 65 years or older are eligible for Medicare under the ACA. The 2004-2017 period was chosen to represent the immunochemotherapy era preceding and following the ACA. Logistic regression was used to explore associations between abstracted variables and insurance status groups. The Kaplan-Meier method and Cox proportional hazards model were used for survival analysis. Results: 93,692 adults (age < 64 years) with newly diagnosed DLBCL and known insurance status were identified (41.3% female, median age 54 years [range: 18 – 64], 81.8% White and 12.1% Black). 7,211 (7.7%) patients were uninsured, 64,744 (69.1%) had private insurance, 11,936 (12.7%) had Medicaid, and 9,801 (10.5%) had Medicare. When compared to insured patients (private insurance, Medicaid or Medicare), uninsured patients were more likely to have a median household outcome of < $38,000 [OR 1.93 (95% CI 1.79-2.07)], less likely to receive chemotherapy [OR 0.69 (0.64-0.77)], more likely to be male [OR 1.14 (1.07-1.21)], more likely to be non-White [OR 1.30 (1.20-1.40], and more likely to present with stage III or IV disease [OR 1.24 (1.16-1.32)]. Uninsured patients had an inferior OS [HR 1.21 (95% CI 1.15-1.27)] when compared to insured patients after adjustment for baseline comorbidity (Charlson-Deyo score ≥2), advanced stage, treatment with chemotherapy, and sociodemographic factors including sex, age, race, household income, facility type (academic/community), and location (urban/rural). With a median follow-up time of 14.8 years (95% CI 14.6-not reached), median OS was lower in uninsured patients [13.4 years (12.3-not reached) vs 14.8 years (14.7-not reached); p < 0.0001]. Despite the lack of major changes in DLBCL therapies, a diagnosis after the implementation of the ACA (in 2010 or later) was associated with a superior OS when compared with the outcomes of patients diagnosed in 2010 or earlier [HR 0.93 (95% CI 0.90-0.95)]. Similarly, five-year OS was superior in the insured group [HR 0.93 (95% CI 0.89-0.96)]. Conclusions: Uninsured patients with DLBCL and < 64 years old had inferior OS when compared with insured patients, and uninsured status emerged as an independent risk factor for inferior OS. Our data highlight the independent effect of insurance disparities - a potential indicator of variations in access to health care - on survival in DLBCL.

7049 Background: Langerhans cell histiocytosis (LCH) can manifest as single system (SS) disease, multisystem (MS) disease, or pulmonary LCH (smoking-related). There is a paucity of data on prognostic factors including risk organ (RO) involvement (liver, spleen, and bone marrow) in adult LCH, which we sought to address in this study. Methods: Single-center retrospective study of patients ≥18y diagnosed with LCH from 1998 to 2020. Univariate and multivariate analyses for progression free survival (PFS) and overall survival (OS) were conducted using age, sex, organ involvement, LCH subtype, year of diagnosis, BRAF V600E status, and treatments. Results: We included 219 patients with LCH; median age 43y (range 19-88), females 51%, SS unifocal (23%), SS multifocal (6%), pulmonary (31%) and MS (40%). Commonly involved organs included lung (53%), bone (42%), skin (24%), pituitary (16%), and CNS (12%). BRAF V600E was positive in 40/88 (46%). Median follow-up duration was 6.1y (95% CI, 5.1- 7.1). On univariate analysis, factors associated with worse PFS were bone LCH, RO involvement, multifocal/MS LCH, and radiation therapy alone; those with worse OS included RO involvement, MS disease, BRAF V600E+, and age ≥45y at diagnosis. In multivariate analysis, BRAF V600E and age ≥45y at diagnosis were associated with worse mortality (Table). Median PFS was not reached (NR-NR) for SS unifocal LCH, 5mo (0-12.7) for SS multifocal LCH, 110mo (84.7-135.3) for pulmonary LCH, and 27mo (17.2-36.8) for MS LCH. 5-year OS was 97.4% for SS unifocal LCH, 100% for SS multifocal LCH, 96.1% for pulmonary LCH, and 79.9% for MS LCH. 41 (18.7%) developed a second primary malignancy (SPM), of which 11 were hematologic neoplasms. There was a trend towards a higher prevalence of SPMs in patients with BRAF V600E (28% vs. 17%; p = 0.22). Conclusions: In our large single-center study, PFS for multifocal and MS LCH was worse than SS unifocal or pulmonary LCH. RO involvement was not associated with outcomes in multivariate analysis. Overall prognosis was excellent for all subtypes except MS LCH. BRAF V600E and older age were associated with worse OS. The prevalence of SPMs was very high and needs to be explored further.[Table: see text]

Abstract Comparative data guiding initial therapy for Waldenström macroglobulinemia (WM), an infrequently encountered non‐Hodgkin lymphoma, are sparse. We evaluated three commonly used rituximab‐based frontline regimens: rituximab‐bendamustine (R‐Benda); dexamethasone, rituximab, cyclophosphamide (DRC); and bortezomib, dexamethasone, rituximab (BDR) in 220 treatment‐naïve patients with WM, seen at Mayo Clinic between November 1, 2000 and October 31, 2019. The median follow‐up was 4.5 (95%CI: 4–5) years. The R‐Benda cohort (n = 83) demonstrated superior overall response rate (ORR: 98%), in comparison to DRC (n = 92, ORR: 78%) or BDR (n = 45, ORR: 84%) cohorts, p = 0.003. Similarly, longer progression‐free survival (PFS) was evident with R‐Benda use [median 5.2 vs. 4.3 (DRC) and 1.8 years (BDR), p < 0.001]. The time‐to‐next therapy (TTNT) favored R‐Benda [median, not‐reached, 4.4 (DRC) and 2.6 years (BDR), p < 0.001). These endpoints were comparable between the DRC and BDR cohorts. Overall survival (OS) was similar across the three cohorts, p = 0.77. In a subset analysis of 142 patients genotyped for MYD88 L265P mutation, the ORR, PFS and TTNT were unaffected by the patients' MYD88 signature within each cohort. In conclusion, ORR, PFS and TTNT with R‐Benda are superior compared to DRC or BDR in treatment‐naïve patients with active WM. The patient outcomes with any one of these three regimens are unaffected by the MYD88 L265P mutation status.

Abstract Abstract Importance: The benefit of routine screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in patients with cancer before cancer-directed therapies is unclear. Herein, we characterize the outcomes of a cohort of cancer patients diagnosed with Coronavirus Disease 2019 (COVID-19) by routine screening in comparison with those diagnosed based on clinical suspicion or exposure history (non-routine screening). Objective: To describe and compare the outcomes of cancer patients diagnosed with COVID-19 on routine screening vs. non-routine screening at a multi-site tertiary cancer center. To identify risk factors for COVID-19-related hospital admission. Design: A multi-site prospective observational study was conducted between March 18 and July 31, 2020. Setting: Three major and 5 satellite campuses of the Mayo Clinic Cancer Center. Participants: Adult patients diagnosed with active cancer within the past five years and confirmed SARS-CoV-2 infection were included. Primary Outcomes and Measures: Clinical and laboratory data were assessed as independent variables. The primary outcome was COVID-19-related hospital admission. Secondary outcomes included intensive care unit (ICU) admissions and all-cause mortality. Results: Between March 18 and July 31, 2020, 5452 patients underwent routine screening in the outpatient setting, 44 (0.81%) were diagnosed with COVID-19. Routine screening detected additional 19 patients from inpatient and pre-procedural settings; 161 patients were diagnosed with COVID-19 based on non-routine screening. The median age of the entire cohort at diagnosis was 54 years, and 95 patients (42.2%) were female. COVID-19 related-hospitalization rate (17.5% vs. 26.7%, p=0.14), ICU admission (1.6% vs. 5.6%, p=0.19), and mortality (4.8% vs. 3.7%, p=0.72) were not significantly different between routine screening and non-routine screening groups. In the multivariable analysis, age ≥ 60 years (odds ratio: 4.4, p=0.023) and an absolute lymphocyte count ≤1.4 × 109/L (odds ratio: 9.2, p=0.002) were independent predictors of COVID-19-related hospital admission. Conclusions and Relevance: The COVID-19 positivity rate was low based on routine screening. Comparing the outcome with the non-routine screening cohort, there was no significant difference. These results led to an important practice change at our cancer center. We currently follow a testing strategy based on symptoms, exposure, risk factors, and clinical judgment. Citation Format: Zhuoer Xie, Antoine N. Saliba, Jithma Abeykoon, Umair Majeed, Daniel Almquist, Julia Wiedmeier-Nutor, Evandro Bezerra, Xavier Andrade-Gonzalez, Ashley Hickman, Karl Sorenson, Sagar Rakshit, Christopher Wee, Sri Tella, Anuhya Kommalapati, Nadine Abdallah, Joshua Pritchett, Mariza De Andrade, Dipesh Uprety, Andrew Badley, Joleen Hubbard, Naseema Gangat, Carrie A. Thompson, Thomas Witzig, Robert R. McWilliams, Konstantinos Leventakos, Thorvardur R. Halfdanarson. Outcomes of COVID-19 in patients with cancer: Results of a prospective observational comparison of routine screening strategy versus testing based on clinical suspicion [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr S06-03.