Treatment Of CLL Research Articles

Current Approaches and Novel Agents in the Treatment of Chronic Lymphocytic Leukemia.

The treatment of CLL has evolved from traditional chemoimmunotherapy (CIT) to an increasing number of targeted and biologic approaches. Randomized trials have demonstrated superiority of covalent bruton tyrosine kinase inhibitors (cBTKis) over CIT, and second-generation compounds such as acalabrutinib and zanubrutinib appear to have a more favorable efficacy/safety profile than ibrutinib. The noncovalent BTKi, pirtobrutinib, has shown impressive activity after failure of the cBTKis and is quite tolerable. The Bcl-2 inhibitor venetoclax plus a CD20, generally obinutuzumab, provides a high level of efficacy as initial treatment or after failure on a cBTKi, with many patients achieving a state of undetectable minimal residual disease. Promising novel approaches include BTK degraders, bispecific antibodies, and chimeric antigen receptor T-cell (CAR-T)-cell therapy. What is clear is that CIT is archaic, and current and future targeted approaches will continue to improve the outcome for patients with chronic lymphocytic leukemia.

Leukemic B cells expression of CD200 and Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1, CD305) in Chronic Lymphocytic Leukemia patients in relation to Treg frequency

BackgroundChronic lymphocytic leukemia (CLL) is characterized by a wide range of tumor-induced immune alterations. Regulatory T cells (Treg) play a central role in these immune responses. CD200 and Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1, CD305) are inhibitory markers said to be involved in Treg immune response. We aimed to analyze the expression of CD200 and LAIR-1 on leukemic cells and assess their interactions with the Treg frequency to elucidate their role in the CLL course. Subjects and methodsThis study was conducted on 70 participants: 50 newly diagnosed CLL cases classified according to Rai staging system into group 1 (n = 25) patients with stages 0, I, and II, and group 2 (n = 25) of advanced patients with stages III and IV. In addition to control group (n = 20) of healthy adults. Flow cytometry was used to investigate Treg frequency in bone marrow (BM) proportional to CD4+ T cell and to assess leukemic cell expression of CD200 and LAIR-1. Also, in-silico database analysis was performed to identify study markers interactions for future personalized target therapy. ResultsComparison between CLL groups 1 and 2 revealed increased leukemic cell percentage expressing LAIR-1 (p = 0.021) in group 1. Group 2 showed significant increase in frequency of Treg in BM and leukemic cells expressing CD200. There was a strong positive correlation between frequency of Treg and leukemic cells expressing CD200 (r = 0.669, p = 0.000). On the other hand, there was a negative correlation between frequency of Treg and leukemic cell expressing LAIR-1 (r = −0.342, p = 0.015). ROC curve analysis revealed that increased frequency of leukemic cells expressing CD200 yielded sensitivity (SN) and specificity (SP) of 96 % and 84 %, respectively in detecting CLL progression, with an AUC of 0.965. Leukemic cell percentages expressing LAIR-1 yielded a lower SN (75 %), SP (72 %), with an AUC of 0.688. ConclusionTreg frequency in BM was significantly increased in CLL advanced stages according to Rai classification. Leukemic cells CD200 and LAIR-1 expression were differently associated with Treg frequency. Increased CD200 expressions on leukemic cells can be considered a sensitive and specific biomarker in detecting CLL progression. As demonstrated by the in-silico research, CD200 blockade targeting may offer therapeutic benefits for CLL treatment through Treg suppression.

Myeloid clonal hematopoiesis of indeterminate potential in patients with chronic lymphocytic leukemia

AbstractClonal hematopoiesis of indeterminate potential (CHIP) in patients with chronic lymphocytic leukemia (CLL) has not been extensively characterized. The objective of this study was to describe the prevalence of myeloid CHIP (M-CHIP) in patients with CLL, and to determine its association with time to first treatment (TTFT) and overall survival (OS). We retrospectively analyzed data from patients participating in a prospective CLL database at the Dana-Farber Cancer Institute who had standard-of-care targeted 95-gene next-generation sequencing (NGS) performed. A schema was devised to classify mutations as M-CHIP related. M-CHIP was analyzed as a binary (present/absent) and categorical (≥2 vs 1 vs 0 mutations) predictor. We included 966 patients (median age at time of NGS, 65 years; 38% female). Overall, 747 (77%) patients had NGS performed before CLL treatment, whereas 219 (23%) had it performed after receiving treatment. Median follow-up time from NGS was 1.9 years. The prevalence of M-CHIP in untreated (12%) and treated (24%) patients with CLL was similar to that described in previous literature. M-CHIP prevalence appeared to increase with age in untreated patients, but appeared consistent across age in treated patients, suggesting that treatment (85% had prior chemotherapy) may have an impact on M-CHIP emergence even in younger patients. The presence of ≥2 M-CHIP mutations was associated with OS, even accounting for prior treatment and age, but was driven by a small subset of patients (n = 28). M-CHIP was not associated with TTFT. These findings support continued work into characterizing the effects of M-CHIP in patients with CLL.

Tuning the B-CLL microenvironment: evidence for BAG3 protein- mediated regulation of stromal fibroblasts activity

The Bcl2-associated athanogene-3 (BAG3) protein, a critical regulator of cellular survival, has been identified as a potential therapeutic target in various malignancies. This study investigates the role of BAG3 within stromal fibroblasts and its interaction with B-cell chronic lymphocytic leukemia (B-CLL) cells. Previous research demonstrated that BAG3 maintains the active state of pancreatic stellate cells (PSCs) and aids pancreatic ductal adenocarcinoma (PDAC) spread via cytokine release. To explore BAG3’s role in bone marrow-derived stromal fibroblasts, BAG3 was silenced in HS-5 cells using siRNA. In co-culture experiments with PBMCs from B-CLL patients, BAG3 silencing in HS-5 cells increased apoptosis and decreased phosphorylation of BTK, AKT, and ERK in B-CLL cells, thus disrupting their pro-survival key signaling pathways. The observation of fibroblast-activated protein (FAP) positive cells in infiltrated bone marrow specimens co-expressing BAG3 further support the involvement of the protein in fibroblast-mediated tumor survival. Additionally, BAG3 appears to support B-CLL survival by modulating cytokine networks, including IL-10 and CXCL12, which are essential for leukemic cell survival and proliferation. A robust correlation between BAG3 expression and the levels of CXCL12 and IL-10 was observed in both co-cultures and patient specimens. These findings point out the need for a more in-depth comprehension of the intricate network of interactions within the tumor microenvironment and provide valuable insights for the selection of new potential therapeutic targets in the medical treatment of CLL.

Mutation in Bruton Tyrosine Kinase (BTK) A428D confers resistance To BTK-degrader therapy in chronic lymphocytic leukemia

Targeting BTK has profoundly changed the face of CLL treatment over the past decade. Iterative advances in the cat and mouse game of resistance and redesign have moved BTK inhibitors from covalent to non-covalent and now targeted protein degraders. However, contrary to the presumption that protein degraders may be impervious to mutations in BTK, we now present clinical evidence that a mutation in the kinase domain of BTK, namely A428D, can confer disease resistance to a BTK degrader currently in clinical trials, that is BGB-16673. Modeling of a BTK A428D mutation places a negatively charged aspartic acid in place of the hydrophobic side chain of alanine within the binding pocket of another BTK-degrader in clinical development, namely NX-2127, suggesting that CLL cells with BTK A428D also may be resistant to NX-2127, as they already are known to be with either non-covalent or covalent inhibitors of BTK. Consequently, the two BTK degraders furthest advanced in clinical trials potentially may select for CLL cells with BTK A428D that are resistant to all approved BTKi’s.

Financial toxicity (FT), quality of life (QoL), and medication adherence patient-reported outcomes (PROs) in CLL on first-line (1L) oral oncolytics.

e23157 Background: While oral oncolytics have transformed CLL treatment, high costs may cause significant FT adversely impacting patients beyond direct out-of-pocket (OOP) costs. The association of FT with QoL and medication adherence has not been characterized with oral oncolytics in CLL. Methods: Electronic PRO surveys were longitudinally administered to patients initiating any 1L oral oncolytic therapy for CLL within the last 6 months at two academic centers. PROs included FACIT-COST (significant FT: score < 26), FACT-LEU QoL, MARS-5 (suboptimal adherence: score < 25) and PROMIS PMAS to assess medication adherence. PROs were administered at baseline, 3 months, and 6 months after enrollment. Pearson’s correlation ( r) was calculated between PRO domains. Semi-structured, qualitative interviews were conducted after 3-month timepoints and analyzed. Results: 34 patients were enrolled: median age 65 yrs (range 33-80), 59% male, 6% Black, 9% Hispanic. Majority received BTK inhibitors (56%, acalabrutinib/zanubrutinib) followed by venetoclax (44%); 50% received concurrent obinutuzumab. Most had private insurance (50%) followed by Medicare (44%). Median time from 1L initiation to study enrollment: 1.5 months. PRO completion rates: 100% (baseline), 85% (3 mo) and 74% (6 mo). Summarized PRO and interview outcomes are displayed below. Conclusions: Patients with CLL on 1L oral oncolytics experienced worsening FT associated with poor medication adherence and worse QoL over time. PROs were discordant with qualitative interviews and suggested that FT may be driven by factors other than OOP costs. Although funding and patient assistance programs were beneficial, uncertainty over losing funding may be a long-term driver of FT and merits further study. [Table: see text]

Reassessing the chronic lymphocytic leukemia International Prognostic Index in the era of targeted therapies

AbstractWe evaluated the chronic lymphocytic leukemia International Prognostic Index (CLL-IPI) in patients with CLL treated first line with targeted drugs (n = 991) or chemoimmunotherapy (n = 1256). With a median observation time of 40.5 months, the 3-year progression-free survival (PFS) rates for targeted drug–treated patients varied by CLL-IPI risk group: 96.5% (low), 87.6% (intermediate), 82.4% (high), and 78.7% (very high). Differences between consecutive CLL-IPI risk groups were observed for intermediate vs low and high vs intermediate, but not very high vs high. CLL-IPI factors β2-microglobulin, immunoglobulin heavy variable (IGHV) status, and TP53 status each retained prognostic value for PFS. The 3-year overall survival (OS) rates by CLL-IPI risk groups were 100%, 96%, 93.9%, and 89.4%, respectively, with no differences between consecutive risk groups. Age, Binet stage, β2-microglobulin, and TP53 status each retained prognostic value for OS. In chemoimmunotherapy patients (median observation time, 66.9 months), 3-year PFS rates for CLL-IPI risk groups were 78.1%, 51.4%, 40.1%, and 16.5%, respectively; corresponding 3-year OS rates were 97.4%, 93.1%, 81.8%, and 57.3%. In a matched-pair analysis, PFS differences in targeted therapies (n = 812) vs chemoimmunotherapy (n = 812) across all risk groups and OS differences in all but patients at low risk were demonstrated. The CLL-IPI maintains its prognostic value in predicting PFS outcomes with targeted drugs, but its impact in predicting survival appears diminished. Targeted therapies showed enhanced outcomes over chemoimmunotherapy, highlighting their effectiveness across various risk groups. Our findings support ongoing assessment of prognostic tools in CLL treatment evolution. These trials were registered at www.ClinicalTrials.gov as #NCT02345863, #NCT02401503, #NCT02689141, #NCT02445131, #NCT02758665, #NCT02950051, #NCT02242942, #NCT00262782, #NCT00281918, and #NCT01010061.

Abstract 1960: CFON-026 is a potent non-covalent BTK inhibitor suitable for combination therapy with covalent BTK inhibitors for early eradication of resistance mutations

Abstract Bruton’s Tyrosine Kinase (BTK) inhibitor drugs are a mainstay in the treatment of CLL, WM and MCL. They are not curative because of the emergence of BTK inhibitor resistance mutations in as much as 67% of relapsed patients (in CLL) [1]. Frequently observed mutations include BTKC481S, which abrogates covalent binding of irreversible drugs such as acalabrutinib, ibrutinib and zanubrutinib, and BTKT474I and BTKV416L which both abrogate binding of the non-covalent inhibitor drug pirtobrutinib [1, 2]. To combat resistance, third generation BTK inhibitors are needed, which must 1. bind to unique regions in the tumor driving kinases that are not marred by resistance mutations, 2. have sufficient potency for sustained inhibition of BTK signaling, and 3. be sufficiently selective to afford efficacious doses and suitable for a combination regimen. We have developed a platform called Energetically Privileged Ligands (EPriLs), based on a macrocycle scaffold that binds non-covalently in the kinase ATP pocket. Their unique binding mode involves connecting the N-terminal and C-terminal lobes of the general kinase fold in a continuous β-sheet, in this way avoiding hotspots for kinase inhibitor resistance mutations. The potent binding of the macrocycle ensures a very long residence time. Using the EPriL platform, we have developed CFON-026, a next generation non-covalent BTK inhibitor with a covalent-like residence time as demonstrated by surface plasmon resonance (SPR) and cellular washout experiments. The biochemical binding KD to BTKWT, determined by SPR, is 0.14 nM. CFON-026 binds mutants with KDs of 0.4 nM (BTKC481S) and and 1.8 nM (BTKT474I). X-ray crystal structures of CFON-026 bound to BTKWT and BTKT474I confirm the unique binding mode and water network around the active site. CFON-026 inhibits the growth of the BTK dependent cell lines TMD8 and Rec-1 with IC50s of 0.45 nM and 1.7 nM, respectively. CFON-026 is very active on TMD8 variants containing endogenous BTK inhibitor resistance mutations (BTKC481S, BTKV416L, BTKT474I and BTKL528W, IC50 range 1-100 nM). CFON-026 has favorable metabolic stability, pharmacokinetic properties, and safety characteristics, and induces complete tumor regression in a TMD8 xenograft model. Since BTK resistance mutations can be detected diagnostically 12-18 months before clinical relapse, CFON-026 could be applied as combination partner to prolong progression free survival on first line BTK inhibitor therapy. Experiments with mixed populations of BTK mutant cell lines, to model a heterogenous tumor, show that CFON-026 can deepen the efficacy of ibrutinib, acalabrutinib and zanubrutinib. In conclusion, CFON-026 is a novel EPriL-based non-covalent BTK inhibitor that could enhance and prolong responses of existing covalent BTK inhibitor therapy. [1] Woyach et al., J Clin Oncol (2017). [2] Wang et al., N. Eng J Med (2022). Citation Format: Jos de Man, Michelle Muller, Joost C.M. Uitdehaag, Freek van Cauter, Sander van Gemert, Milan Hoffmann, Yvonne G.T.H. van Mil, Winfried R. Mulder, Martine B.W. Prinsen, Jan Gerard Sterrenburg, Diep Vu, Joeri de Wit, Erik Ensing, Rogier C. Buijsman. CFON-026 is a potent non-covalent BTK inhibitor suitable for combination therapy with covalent BTK inhibitors for early eradication of resistance mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1960.

Disparity in treatment patterns among Medicare beneficiaries diagnosed with chronic lymphocytic leukemia: an analysis of patient and contextual factors

This study characterizes the patterns and timing of CLL treatment and, to our knowledge, is the first to identify social vulnerability factors associated with CLL treatment receipt in the Medicare population. A total of 3508 Medicare beneficiaries diagnosed with CLL from 2017 to 2019 were identified. We reported the proportion of individuals who received CLL treatment and the time until the first CLL treatment receipt after the first observed claim with a CLL diagnosis. Logistic regression and time-to-event models provided adjusted odds ratios and hazard ratios associated with baseline individual-level and county-level factors. Sixteen percent of individuals received CLL treatment, and the median follow-up time was 540 d. The median time to receipt of CLL treatment was 61 d. Older age and residence in a county ranked high in social vulnerability (as defined by minority status and language) were negatively associated with treatment receipt and time to treatment receipt.

Benefit with MRD-guided treatment in CLL.

Benefit with MRD-guided treatment in CLL.

Treatment of Chronic Lymphocytic Leukemia in the Personalized Medicine Era.

Chronic lymphocytic leukemia is a lymphoproliferative disorder marked by the expansion of monoclonal, mature CD5+CD23+ B cells in peripheral blood, secondary lymphoid tissues, and bone marrow. The disease exhibits significant heterogeneity, with numerous somatic genetic alterations identified in the neoplastic clone, notably mutated TP53 and immunoglobulin heavy chain mutational statuses. Recent studies emphasize the pivotal roles of genetics and patient fragility in treatment decisions. This complexity underscores the need for a personalized approach, tailoring interventions to individual genetic profiles for heightened efficacy. The era of personalized treatment in CLL signifies a transformative shift, holding the potential for improved outcomes in the conquest of this intricate hematologic disorder. This review plays a role in elucidating the evolving CLL treatment landscape, encompassing all reported genetic factors. Through a comprehensive historical analysis, it provides insights into the evolution of CLL management. Beyond its retrospective nature, this review could be a valuable resource for clinicians, researchers, and stakeholders, offering a window into the latest advancements. In essence, it serves as a dynamic exploration of our current position and the promising prospects on the horizon.

Health Care Resource Utilization (HCRU) and Cost of Management of Cytokine Release Syndrome (CRS) and Neurological Events (NEs) in Patients with R/R CLL/SLL Receiving Lisocabtagene Maraleucel (liso-cel) Treatment in the TRANSCEND CLL 004 Study

Background:Liso-cel is an autologous, CD19-directed, 4-1BB CAR T cell product administered at equal target doses of CD8 + and CD4 + CAR + T cells, which is currently being evaluated for treatment of patients with R/R CLL/SLL in the TRANSCEND CLL 004 study (NCT03331198). Initial study results suggested that a single infusion induced CRs or remission in patients with R/R CLL/SLL and had a manageable safety profile, with low to moderate incidence of severe CRS and NEs (Siddiqi T, et al. Lancet 2023). While the clinical consequences of CRS/NEs associated with CAR T cell therapies are well understood, limited data are available on the cost of management of these AEs. This analysis evaluated HCRU and estimated costs of managing CRS/NEs by grade in patients with R/R CLL/SLL who received liso-cel treatment in TRANSCEND CLL 004. Methods: Case report forms were analyzed from the trial database, capturing patient-level HCRU related to the management of CRS/NEs. Only patients that received liso-cel at a dose level of 100 × 10 6 CAR + T cells (dose level 2 [DL2]) and subsequently experienced treatment-emergent CRS and/or NEs were included in this study. Treatment-emergent AEs were defined as those initiated within a 90-day period of liso-cel administration. Costs for management of CRS/NEs were estimated using microcosting methodology. Relevant HCRU observed from the day of AE onset through resolution that was associated with the management of CRS/NEs per protocol management guidelines was identified; unit costs sourced from public databases were applied to each HCRU. Included HCRU categories were: facility (standard inpatient admission, ICU stay), diagnostics (laboratory, imaging), medications (tocilizumab, corticosteroids, vasopressors), and procedures (dialysis, intubation). Cost analyses were conducted from the United States (US) health care system perspective and adjusted to 2023 US dollars. Unit costs were obtained from the US Centers for Medicare & Medicaid Services Hospital Outpatient Prospective Payment System, laboratory and physician fee schedules, IBM ® Micromedex ® RED BOOK ®, and literature. Descriptive statistical analyses stratified by AE severity grade and type of AE experienced were performed. Results: Ninety-four of 108 (87%) patients who received liso-cel at DL2 experienced CRS and/or NEs; 68 (72%) were grade ≤ 2 and 26 (28%) were grade ≥ 3. Overall, 44 (47%) patients had CRS only, 1 (1%) had NEs only, and 49 (52%) experienced both CRS and NEs. The study sample had a mean (standard deviation) age of 64.5 y (7.9) and were predominantly male (69%), White (84%), and non-Hispanic or Latino (90%). HCRU and total length of stay (LOS; the sum of inpatient and ICU stay days) are shown in the Table. All patients had an inpatient stay. ICU admissions only occurred among patients who experienced both CRS and NEs (10/49 [20%]) and were more common among patients with grade ≥ 3 (29%) compared with grade ≤ 2 (12%) AEs. Among patients who had an ICU admission, the median duration of an ICU stay was 5 days. Median total LOS increased with increasing AE severity for patients who had CRS only (grade 1, 5 days; grade 2, 9 days; grade 3, 15 days) and for patients who experienced both CRS and NEs (grade ≤ 2, 12 days; grade ≥ 3, 15 days). Overall, 68% and 62% of patients received tocilizumab and corticosteroids, respectively. Patients with grade ≥ 3 CRS and/or NEs had higher rates of utilization of medications, diagnostics, and procedures than those with grade ≤ 2 (Table). Additionally, patients who experienced both CRS and NEs had higher rates of utilization across all HCRU categories compared with those who experienced CRS or NEs only (Table). Estimated median management costs for CRS or NEs ranged from $14,638 (CRS only grade 1) to $46,802 (experienced both CRS and NEs with CRS or NEs grade ≥ 3) (Figure). Facility-related costs were the largest contributor to median total costs. Conclusions: While most patients treated with liso-cel at DL2 in TRANSCEND CLL 004 experienced CRS and/or NEs, they were primarily of low severity. HCRU and associated costs for management of CRS and/or NEs after liso-cel infusion increased with AE severity.Although everyone in this study required hospitalization, ICU admissions were rare and only observed among patients who experienced both CRS and NEs. Overall, costs of managing CRS and/or NEs were modest.

How Can You Use Newer Therapies to Improve Clinical Decision-Making and Long-Term Health Outcomes for Patients with Chronic Lymphocytic Leukemia Acute Myeloid Leukemia?

The Catalyst initiative, developed by Med Learning Group in 2019 with continued grant support year-on year, is a comprehensive continuing medical education platform that provides innovative methods to increase HCPs' competence surrounding essential aspects of CLL and AML management, with a specific focus on molecular testing, therapy selection, and the combination of established and emerging treatments. By equipping healthcare professionals with up-to-date knowledge and skills, the Catalyst initiative empowers them to make informed decisions that lead to improved patient outcomes. The Catalyst website (www.Catalyst-HM.com) includes HCP- and patient-facing and serves as a validated platform for the latest guidelines and research on CLL and AML. There have been over 16500 views of the website since its launch in 2019. Learners also have access to a variety of accredited educational programs and tools, such as downloadable animations illustrating the value of molecular testing and how to use results to guide treatment choice and a Personalized Poster Portal where learners can choose a variety of images for a poster that is sent to their practice setting. In 2021/2022, these live and online programs have educated over 10000 HCPs Learners have particularly appreciated the innovative nature of the CATALYST Initiative, with 98% indicating the VR animations included in a variety of programming improved their learning experience and knowledge retention (N=2997). At the last two ASH annual meetings, learners could participate in the CATALYST VR Room, a digital version of which can be viewed here: https://catalyst-hm.com/virtualbooth/. Please view footage and attitudinal feedback from learners here. The proposed poster would review the gains in knowledge and competence among CATALYST learners longitudinally from 2019 - 2022, demonstrating the value of this community in helping to advance the translation of the latest science to practice behavior. As demonstrated in the figure below (Please see figure 1), in 2022 hematologists / oncologists increased their ability to apply treatment best practices in newly diagnosed and R/R AML by 28%, and their ability to individualize selection of therapies for treatment-naïve and R/R CLL based on disease- and patient-specific factors 31% (N=2953). While these are significant gains, baseline pre/posttest scores in the sixtieth percentile among specialists suggest these are important areas for continued focus. The CATALYST program has also had a significant impact on learners' practice, based on 60- and 90-day follow-on assessments (n=113). 87% of respondents indicate they now actively use strategies and tools to address adverse events in the treatment of CLL or AML with all or most of their patients. Additionally, 79% indicated increased incorporation of patient and disease-specific factors when treating newly diagnosed or relapsed/refractory AML patients. Over the last four years, the Catalyst initiative has helped the oncology/hematology multidisciplinary team increase their ability to utilize molecular and genetic features as well as patient characteristics to design individualized management plans to enhance patient outcomes. The proposed poster will describe CATALYST offerings and demonstrate its impact on HCPs' ability to translate the latest data and guidelines to practice for their patients with AML and CLL.

The Total Lifetime Cost of Treating Patients (Pts) with CLL in the United States (US)

Background:CLL is the most common form of leukemia in pts aged ≥ 19 y and accounts for 38% of all new leukemia cases. The CLL treatment (tx) paradigm changed after the introduction of oral targeted therapies (Bruton tyrosine kinase inhibitors [BTKi] and B-cell lymphoma 2 inhibitors). However, relapses after tx are common, and these txs come with a high cost. Limited data exist evaluating the lifetime cost of treating pts with CLL with current therapies. The objective of this study was to estimate the total lifetime cost of treating pts with CLL in the US from the health system perspective. Methods: A semi-Markov model with a lifetime horizon was developed to estimate the per-pt cost of treating CLL. The model consisted of 6 distinct health states, including tx by line of therapy (LOT; first line [1L] through fifth line and later [5L+]) and death. Pts entered the model in the 1L. CLL txs selected for inclusion were those most commonly used according to market share data and recommended by National Comprehensive Cancer Network guidelines. Tx categories included ibrutinib ± anti-CD20 monoclonal antibody (mAb), acalabrutinib ± anti-CD20 mAb, venetoclax-based regimens, chemoimmunotherapy, and phosphatidylinositol 3-kinase inhibitor-based regimens. Transition probabilities and time spent on each LOT were calculated based on data abstracted from digitized time to next tx (TTNT) and OS Kaplan-Meier curves from real-world studies. Tx-specific data were applied for 1L and second-line (2L) txs, and data pooled across txs for each LOT were applied for third line (3L) through 5L+. TTNT and OS data from the literature were extracted for the duration of available follow-up. Best-fitting parametric survival models were used for reasonable extrapolation of TTNT data beyond the limited follow-up. OS beyond the available follow-up was estimated based on survival data from US life tables adjusted for each tx via a calculated tx-specific HR. Costs associated with drug acquisition and administration of CLL txs, inpatient stays, outpatient visits, emergency department (ED) visits, Richter's transformation (RT), end-of-life care, and other health care resource utilization (HCRU) were included in the model. AE management costs were assumed to be captured within inpatient costs and therefore not included separately in the model. Inputs were derived from published literature and publicly available sources. At the point of entry into the model, the study cohort was assumed to be 70 y old and included 64% males, based on median age and sex distribution reported in the literature (Mato et al. Clin Lymphoma Myeloma Leuk 2023). All costs were converted to a health system perspective, discounted 3% per year, and adjusted to 2023 US dollars (USD). Model outcomes included per-pt total expected lifetime cost and total expected lifespan. A scenario analysis was conducted to calculate per-pt-per-year (PPPY) cost of each LOT. A 1-way sensitivity analysis was conducted to identify key drivers of the total lifetime cost. Results: The total expected lifetime cost of treating a pt with CLL in the US was estimated to be $1,142,357. The estimated total time spent in the model was 8.03 y. Drug costs were the largest driver of the total lifetime cost (77%), followed by inpatient and ED costs (20%; Table). The majority of time was spent in 1L and 2L (6 and 1.68 y, respectively). The probability of receiving 2L, 3L, fourth-line (4L), and 5L+ therapy was estimated to be 44%, 16%, 6%, and 4%, respectively. In the scenario analysis, the annual cost in each LOT ranged from $140,867 to $234,807 PPPY, with costs increasing with each subsequent LOT (Figure). The 1-way sensitivity analysis showed that lifetime costs were mainly driven by drug acquisition costs, especially BTKi such as ibrutinib and acalabrutinib, as well as the cost of venetoclax. Other key drivers of the total expected lifetime cost included hospitalization costs and pt starting age. Conclusions:Study results showed that the expected lifetime cost of treating a pt with CLL in the US is high. Drugs (especially oral targeted txs) were the top drivers of lifetime total cost. As expected, scenario analysis showed that the economic burden increased with each LOT. Given the high lifetime economic burden of this disease, there is a need for potentially more effective 1-time-only tx options.

Safety Profile in Patients with Chronic Lymphocytic Leukemia Undergoing Treatment with 1st and 2nd Generation Bruton Tyrosine Kinase Inhibitors: Multicentric Real-World Experience

INTRODUCTION Chronic lymphocytic leukemia (CLL) is the most frequent leukemia, being more frequent in older adults. Bruton's tyrosinkinase inhibitors (BTKi) have revolutionized the treatment, displacing immunochemotherapy treatment in all patient profiles. The selectivity profile in the action of these drugs means that the toxicity of first and second generation BTKi is different, resulting in higher rates of atrial fibrillation and arterial hypertension, mainly in patients treated in the second line or later, while maintaining their efficacy. Real-life studies are needed to be able to demonstrate the effects in first-line treatment in a more heterogeneous patient profile, without the strict exclusion and inclusion criteria used in clinical trials. METHODS An observational, retrospective, multicenter, retrospective study was performed. Patients with in treatment with Ibrutinib or Acalabrutinib in first line or later were included. Demographic data, comorbidity, cytogenetic and mutational disease data, adverse effect profile, comprehensive geriatric assessment (if applicable) and treatment response evaluation data are collected. RESULTS A total of 91 patients were included with a median age of 73.22 years SD 11.06. Fifty-three (58.2%) were male. Fifty-three (58.2%) were treated in frontline, 31.9% (29) in second line and 9.9% (9) in subsequent lines. Acalabrutinib was used in 25 (27.5%) patients and Ibrutinib in 66 (72.5%). Patient characteristics are shown in Table 1. Differences were revealed between these two BTKis in terms of line of treatment, with the majority being treated first (P=0.006) and Rai stage, with Rai II predominating (P=0.014). No differences were found between the two BTKis according to the rest of the characteristics. In terms of toxicity, 14 (15.4%) of patients treated with Ibrutinib developed arterial hypertension, compared to no patients in the Acalabrutinib arm (p=0.009). With respect to the development of cardiac toxicity, 19 (20.9%) patients suffered some cardiotoxic event, 3 (3.3%) in patients on acalabrutinb and 16 (17.6%) on ibrutinib, with no significant differences found between the two drugs (p=0.2). No significant differences were found with respect to other toxicities (hematologic, digestive, bleeding and infections). Table 2 No differences were found in terms of progression-free survival or overall survival. CONCLUSIONS The iBTKs have changed the treatment of CLL, although the second-generation iBTKs have a safer cardiovascular profile and are just as effective in our cohort, even in the frontline.

Single-Cell Long-Read Sequencing Enables the Dissection of BTK Subclonal Dynamics in CLL Treatment

Introduction: BTK inhibition is an effective frontline therapy for patients with CLL. However, patients who develop BTK C481S mutations relapse quickly. We recently published a longitudinal study investigating subclonal evolution in 38 patients receiving BTKi treatment for CLL. Of the 38 patients, 6 developed a subclone containing a BTK C481S mutation identified in the whole-exome sequencing (WES) data at the time of relapse. To understand whether a BTK C481S mutation alone can drive relapse or if an additional CLL-relevant mutation is required, we investigate these subclones on a single-cell level using PacBio Multiplexed Arrays Sequencing (MAS-seq). MAS-seq generates single-cell, long-read RNA sequencing data, which is highly accurate and provides coverage across the entire mRNA transcript. Methods: For each patient, B cells were isolated from a pre-BTKi treatment sample and a sample taken at the time of relapse. Single-cell cDNA library preps were generated using the 10X Genomics Chromium platform. The cDNA was then sequenced using MAS-Seq. After processing the MAS-seq data using PacBio's Isoseq pipeline, Seurat was used to perform a single-cell analysis for each sample. We used scBayes, a Bayesian-statistical approach developed in our lab (Qiao et al., Genome Research, in review), to assign subclone identity to individual cells based on the expression of previously identified somatic mutations. The transcript-wide coverage of MAS-seq increases the likelihood of coverage at the somatic mutation sites compared to traditional single-cell RNA sequencing methods. Results: We have sequenced and analyzed samples from 4 patients in this study (pt 1-4). In the pretreatment sample of pt 1, two subclones containing different TP53 mutations were present. At the time of relapse, a BTK C481S subclone evolved from one of these TP53 subclones, becoming the dominant clonal population. No other CLL-relevant mutations were detected in this patient. Pts 2-4 had an additional CLL-relevant mutation evolve with the BTK C481S mutation in the dominant subclone at the time of relapse. In pt 2, a subclone with an NFKBIE and the BTK mutation evolved from a cell population where BRAF, BCOR, and EGFR2 mutations were present. The BTK C481S subclone in Pt 3 also had new KMT2D and CREBBP mutations. This subclone evolved from a cell population with an ASXL1 and SF3B1 mutation. In pts 1-3, the BTK subclone was only seen at the time of relapse. Pt 4 did not have any CLL-relevant mutations identified before treatment. In a sample taken 6 months before relapse, a BTK C481S subclone is visible at a low frequency with no other CLL-relevant mutations. At the time of relapse, a DICER1 variant, a gene recently implicated in CLL (Knisbacher et al., Nature Genetics, 2022), evolved from the BTK subclone and is seen at the time of relapse as the dominant subclone. Furthermore, the full-transcript sequencing at the single-cell level enabled us to identify a second BTK C481S subclone present at the time of relapse and determine that it was independent of the subclone containing both the BTK C481S and DICER1 mutations. This second BTK subclone had no other CLL-relevant mutations and remained at a very low frequency. Conclusion: Single-cell long-read RNA sequencing via MAS-seq provides transcript-wide coverage, which enables genotyping at somatic mutation sites. Using this method, we found that the dominant relapse clones all contained a BTK C481S mutation, which either co-evolved with additional CLL-relevant mutations (3/4 patients) or occurred on the background of existing TP53 mutations (1/4 patients).

First Report of Phase 1 Studies of DZD8586, a BBB Penetrant LYN/BTK Dual Inhibitor, in Patients with B-Cell Non-Hodgkin Lymphoma (B-NHL)

Introduction Resistance to covalent (ibrutinib, acalabrutinib and zanubrutinib) and non-covalent BTK inhibitors (pirtobrutinib) is an emerging clinical challenge. DZD8586 was designed as a full blood-brain barrier (BBB) penetrable LYN/BTK dual inhibitor. Preclinical study suggested DZD8586 has a good selectivity against other TEC family kinases (TEC, ITK, TXK, BMX). DZD8586 inhibits BTK-dependent and BTK-independent BCR signaling pathways by targeting LYN and BTK, which could potentially overcome resistance to both covalent and non-covalent BTK inhibitors for the treatment of CLL and MCL, as well as DLBCL. Two phase 1 clinical studies are ongoing in patients with relapsed or refractory (r/r) B-NHL to assess safety, pharmacokinetics (PK), pharmacodynamics (PD) and anti-tumor efficacy of DZD8586. Methods TAI-SHAN1 (NCT05844956; CTR20220558) and TAI-SHAN5 (NCT05824585) are phase 1 dose escalation and expansion studies in patients with r/r B-NHL. Both studies have similar dose escalation strategies. Patients who progressed following or intolerant of prior systemic therapy were enrolled. Pooled safety and efficacy analysis was performed. In addition, modulation of PD biomarkers was also evaluated. Tumor responses were investigator assessed according to Lugano 2014, IPCG 2005, or iwCLL 2018, as appropriate. Results As of June 15, 2023, 17 patients with r/r B-NHL have been enrolled and received DZD8586 at doses ranging from 10 to 100 mg once daily (QD) (10 mg， n=1；25 mg， n=4；50 mg， n=7；100 mg， n=5). The median age was 61 years, 71% were male, and 53% had an ECOG PS of 1. Histological subtypes included CLL, SCNSL, DLBCL, MCL, FL and MZL. The median number of prior therapies was 3 (range 2 - 8). All patients received prior chemotherapy and anti-CD20 therapy. Six patients, including 1 CLL, 2 MCL, 1 MZL, 1 SCNSL and 1 DLBCL had received prior treatment with covalent BTK inhibitors. DZD8586 was well tolerated across the doses investigated. Drug-related treatment emergent adverse events (TEAEs) reported in > 2 patients included thrombocytopenia (10/17), neutropenia (5/17), and upper respiratory tract infection (3/17). The most common ≥ grade 3 TEAE was thrombocytopenia (3/17, all at 100 mg). Other ≥ grade 3 TEAEs, including neutropenia, drug eruption and upper respiratory tract infection, were each reported by one patient. Bleeding, atrial fibrillation, and arthralgia were not reported. Grade 1 diarrhoea was reported in one patient. The maximum tolerated dose was defined as 100 mg QD. All these TEAEs were reversible after dose interruption and/or with supportive care. The longest duration on treatment was 10+ months. Among 13 patients treated at doses ≥ 25 mg QD with at least one tumor assessment, the objective response rate (ORR) was 9/13 (69.2%). Responses were observed across different histological subtypes (1/2 in SCNSL; 4/5 in DLBCL; 1/2 in FL; 1/1 in MCL, 1/2 in MZL and 1/1 CLL carrying C481S mutation). Among the 5 evaluable BTKi treated patients, tumor responses were observed in 3 patients. The longest duration of response (DoR) was 6.4+ months, and the patient was still ongoing with DZD8586 treatment and responding. PK was generally dose-proportional across the dose ranges of 10 to 100 mg. DZD8586 was absorbed with median t max 1.5 hours, and eliminated with mean terminal half-life of ~18 hours. Accumulation of about two folds in AUC was noted at steady state following once daily dosing. Dose dependent pBTK modulation in whole blood cells was detected, and at the doses ≥ 25 mg, sustained pBTK inhibition was observed. The unbound CSF-to-plasma concentration ratio (K puu,CSF) was 1.2 from one CNSL patient with available CSF samples, suggesting excellent CNS penetration of DZD8586 in humans. Conclusion In the preliminary pooled analysis of two ongoing phase 1 trials, DZD8586 has encouraging anti-tumor activity and safety in heavily pre-treated B-NHL patients. The combination of BBB penetration, dual inhibition of LYN/BTK and potential to overcome C481S mutant CLL and other covalent BTKi resistant lymphomas suggest this may be a useful agent. Updated data will be presented at the meeting.

Initial Results of a Phase 2 Study of Venetoclax Added to Ibrutinib to Eliminate Ibrutinib Resistance Mutations in CLL

CONCLUSION BTK inhibitors (BTKi) are an important treatment for CLL. As BTKi are given until intolerance or disease progression, resistance is a major challenge. Progressive disease (PD) during BTKi treatment is associated with mutations BTK itself, or the immediate downstream protein, PLCG2. These can be detected 9-12 months prior to PD allowing for intervention. Venetoclax (VEN) is effective after IBR treatment, decreases BTK C481S mutation VAF, and can be combined with IBR. Based on these data, this phase 2 study adding VEN to IBR in patients (pts) with resistance mutations (RMUT) was conducted to test the hypothesis that adding VEN could eliminate molecular resistance. CLL pts taking IBR and with a detectable RMUT with or without PD were eligible. Included RMUT were in BTK at C481 and T474 or in PLCG2 at L845, D334, D1140, R665, and S707. Eligible pts continued IBR and added VEN. VEN was given in cycles (C) of 28 days with standard 5-week dose ramp-up to 400mg daily. Response was assessed after C12 and C24 by iwCLL 2008 criteria. Pts achieving a complete remission (CR) or CR with incomplete marrow recovery (CRi) and undetectable minimal residual disease (uMRD) to a level of 10-4 in both blood and marrow discontinued treatment. Those without a uMRD CR/CRi continued through C24 then discontinued if in uMRD CR/CRi. If this response was still not achieved after C24, they stopped IBR and continued VEN alone. Sequencing for RMUT was performed using an assay with a sensitivity of ≥0.5% VAF on sorted CD19+ B-cells. The primary endpoint is the rate of undetectable RMUT after C12 of IBR and VEN. Secondary endpoints are rate of uMRD CR/CRi after C12, progression-free (PFS), and overall survival (OS). C12 assessments missed due to the COVID-19 pandemic were considered non-assessable (NA). A second analysis included delayed C12 assessments. Adverse events (AEs) were graded according to the CTCAE v5 except hematologic AEs which used iwCLL criteria. Kaplan Meier methods were used to assess PFS and OS. All statistical analyses were performed using SAS version 9.4 (SAS Institute, Inc., Cary, NC). Data cut was 7/13/2023. A total of 28 pts were enrolled between 3/2019 and 2/2022 with baseline characteristics in the Table. The median follow up was 31.7 months (range 2.8-47.0) and 8 (29%) pts remain on treatment, 9 (32%) in follow up off treatment, 10 (40%) off study, and 1 (4%) died. BTK C481S testing was available after baseline at time of analysis. After C12, 13/27 (48%) pts who had a BTK C481S mutation at baseline had undetectable BTK C481S (uBTK C481S). This increased to 16/27 (59%) with C12 delayed assessments. 19/27 (70%) pts had uBTK C481S at anytime on study with a median time to uBTK C481S of 6 months (range 2.0-19.8). Of these 6/19 (32%) regained detectable BTK C481S with a median duration of uBTK C481S of 13.8 months (range 5.3-28.8) and 3/6 had PD. After C12 the overall response rate (ORR) was 71% (4 CR, 4 CRi, 12 partial remissions [PR], 4 stable disease [SD], 1 PD, 3 NA). Including delayed assessments (at C16, C19, and C19), the ORR was 79% (NA->PR n=2, PR->CR n=1). uMRD CR/CRi was attained in 5/28 (18%) and 6/28 (21%) pts after C12 and including delayed assessments, respectively. 12/28 (43%) pts discontinued treatment due to response: 9/28 (32%) in uMRD CR/CRi (C12 n=4, C19 n=1, C25 n=4), 3/28 (11%) electively in CR with detectable MRD (n=1, C12) or PR with uMRD (n=2, C25). Eight (36%) pts had PD with 1 Richter Transformation. The median PFS and OS were 40.7 months (95% CI: 35.9-not reached) and not reached, respectively (Figure). Hematologic AEs were frequent with lymphopenia (75%, 46% grade [gr] 3+), thrombocytopenia 68%, 7% gr 3+), neutropenia (61%, 14% gr 3+), and anemia (43%, 0% gr 3+). AEs experienced by >40% of pts were hypocalcemia (75%), diarrhea (75%), weight loss (57%), hypertension (57%), increased lactate dehydrogenase (54%), nausea (54%), dizziness (50%), vomiting (50%), flu like symptoms (43%), and neoplasms (43%). Gr 3 non-hematologic AEs occurring in >10% of pts were hypertension (21%) and diarrhea (14%). Seven (25%) patients had COVID-19 (all gr 2). There were no episodes of tumor lysis syndrome. In this phase 2 study, the addition of VEN to IBR decreased the BTK C481S mutation below the detection limit in 59% of pts after 12 cycles of treatment. This combination allowed 32% of pts to discontinue treatment in deep remission. The median PFS (40.7 months) supports further investigation of this approach.

CLL Cell-Derived Exosomes Impair Immune Function and Normal Hematopoiesis in CLL

CLL is characterized by immune and hematopoietic abnormalities such as T-cell dysfunction, hypogammaglobulinemia, increased levels of inflammatory cytokines, aberrant monocyte polarity, anemia, neutropenia, and low-grade bone marrow fibrosis. As a result, CLL patients become susceptible to increased rates of infection and/or second neoplasms. Exosomes are nanovesicles that participate in bidirectional communication between neoplastic cells and their microenvironment. Using electron microscopy, we found that CLL cells produce and release CD19 +/CD5 +exosomes, and in agreement with other investigators, we detected high levels of CLL cell-derived exosomes in the plasma of patients with CLL. By using bead-assisted flow cytometry, we found that at least 50% of circulating extracellular vesicles are CLL cell-derived exosomes, identified as CD63 +/CD41a - particles co-expressing CD19 +/CD5 +, whereas only a small proportion of CLL patients' plasma-derived exosomes expressed T-cell or endothelial cell surface markers. Furthermore, we found a positive correlation between levels of CLL cell-derived exosomes in the plasma of patients with CLL and the patients' peripheral white blood cell counts, indicating that CLL cells are the primary source of circulating exosomes. To investigate the effects of CLL cell-derived exosomes, we conducted an analysis of CLL cells and CLL cell-derived exosomes from a cohort of 78 previously untreated patients. To identify the molecular profiles of CLL cell-derived exosomes, we analyzed their RNA transcripts using RNA-seq and qRT-PCR. Our data revealed that CLL cell-derived exosomes expressed significant levels of oncogenic micro-RNAs. Additionally, we identified 1052 differentially expressed genes, and enrichment analysis further unveiled the significant upregulation of gene clusters associated with p53, NF-κB, MAPK, mTOR, and interleukin signal transduction pathways, consistent with their neoplastic cell origin. The distinctive transcriptional profile of CLL cell-derived exosomes led us to explore their effects on normal cell populations. We labeled ultra-centrifuged CLL cell-derived exosomes with fluorescent markers and incubated them with various cell types in culture conditions conducive to their physiological activity. Using confocal microscopy and flow cytometry, we observed significant uptake of CLL cell-derived exosomes by normal monocytes, fibrocytes, B cells, T cells, and CLL cells. Furthermore, incubation with CLL exosomes resulted in notable alterations in normal CD14 + monocyte polarity and subset-specific shifts in the expression of inflammatory cytokines. Remarkably, CLL cell-derived exosomes induced overexpression of the T-cell makers CD5 and CD8 in normal CD19 + cells, suggesting that CLL exosomes may promote immune-evasive reprogramming of normal B cells. Moreover, when normal T cells were incubated with CLL cell-derived exosomes, CyTOF analysis using 46 markers revealed elevated levels of immune checkpoints, including PD1, CTLA4, and LAG3, in both CD4 + and CD8 + subsets, indicating that exosomes derived from CLL cells induce T-cell dysfunction. Given their profound effect on immune cells, we wondered whether CLL exosomes affect hematopoietic cells. We previously found that normal monocyte derived fibrocytes stimulate hematopoietic colony proliferation. In sharp contrast to control fibrocytes, fibrocytes preincubated with CLL exosomes and CLL cell-derived exosomes inhibited normal BFU-E and CFU-GM colony formation, suggesting that CLL exosomes might contribute to CLL patients' anemia or neutropenia. Wondering whether CLL cell-derived exosomes affect the viability of other cell types, we found that they induced a dose-dependent apoptosis of CD19 + B cells, CLL cells but not normal T cells. In summary, CLL cell-derived exosomes exert a profound effect on gene and cell surface protein expression in immune and tissue-remodeling cells, leading to functional modifications, alteration of inflammatory cytokine levels, and suppression of normal hematopoiesis. The impact of CLL exosomes may vary across different cell types; however, as the leukemic cell mass increases, exosome levels escalate, invariably affecting CLL cell environment. The identification of exosomes with distinct molecular signatures holds promising potential for novel therapeutic interventions in future treatment of CLL.

Incidence of Richter Transformation in Patients with Chronic Lymphocytic Leukemia (CLL) /Small Lymphocytic Lymphoma (SLL): A Cohort Study Evaluating Different Therapeutic Eras

INTRODUCTION Richter transformation (RT) is the histologic transformation of CLL/SLL into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). We previously reported an incidence of 0.5% per year of RT in patients with newly diagnosed CLL and an incidence of 1% per year following initiation of therapy (Parikh, BJH, 2013). It is unknown whether these incidences have changed in the novel agent era. METHODS We identified patients with previously untreated CLL/SLL in the Mayo Clinic CLL Database who were seen within 12 months of diagnosis. Only patients with biopsy-proven DLBCL with histopathology confirmation at Mayo Clinic were included. Cumulative incidence methodology was used to display the time to development of RT with death as a competing risk (both from time of initial CLL/SLL diagnosis, and from start of CLL directed therapy). We defined the time period prior to February 2014 (FDA approval of ibrutinib for CLL) as the pre-novel agent era and the time period starting February 2014 as the novel agent era. Using Cox regression analysis, we compared the incidence of RT, both after initial CLL diagnosis and after initiation of CLL therapy, between patients diagnosed with CLL in the pre-novel agent era versus the novel agent era. RESULTS Between 1/2000 and 4/2023, 3347 patients were seen at Mayo Clinic. The median age at diagnosis was 65 years (range 21-97 years), and 66% patients were male. Baseline characteristics of patients at the time of CLL and RT diagnoses between the two treatment eras were similar, including distance in miles of primary residence from Mayo Clinic ( Table 1). The median follow-up for the entire cohort was 5.6 years (9.5 years for the pre-novel agent era cohort and 3.2 years for the novel agent era cohort). A total of 82 patients were diagnosed with RT (69 in the pre-novel agent era and 13 in the novel agent era). Overall, the 1-, 5- and 10-year cumulative incidence rates for RT from the time of CLL/SLL diagnosis were 0.6% (95% CI: 0.4-0.9%), 1.8% (95% CI: 1.3-2.3%), and 3.0% (95% CI: 2.4-3.8%), respectively. Among the patients who received CLL/SLL therapy (n=1382), the 1-, 5-, and 10-year incidence rates for RT from the time of treatment start were 0.3% (95% CI: 0.1-0.8%), 3.3% (95% CI: 2.4-4.5%), and 4.9% (95% CI: 3.7-6.5%), respectively. Among 1981 patients diagnosed with CLL/SLL in the pre-novel agent era, the 1- and 5-year incidence rates for RT from the time of diagnosis were 0.6% (95% CI: 0.4-1.1%) and 2.1% (95% CI: 1.5-2.8%), respectively. Among 1366 patients diagnosed with CLL/SLL in the novel agent era, the 1- and 5-year incidence rates following CLL/SLL diagnosis were 0.5% (95% CI: 0.2-1.1%) and 1.1% (95% CI: 0.6-2.2%), respectively. The RT incidence from time of CLL/SLL diagnosis was not significantly different between the pre-novel agent and novel agent era patients (hazard ratio [HR] 1.6, 95%CI 0.9-3.0, p=0.13). Patients who received CLL/SLL treatment in the pre-novel agent era (n=926) and novel agent era (n=456) had subsequent 1-year incidence rates of RT of 0.3% (95% CI: 0.1-1.0%) and 0.2% (95% CI: 0.0-1.8%), respectively. The 5-year incidence rates for these groups were 3.7% (95% CI: 2.6-5.2%) and 1.9% (95% CI: 0.7-5.0%), respectively. Although an increased risk of RT after CLL/SLL directed therapy was observed in the pre-novel agent era compared to the novel agent era (HR 2.4, 95%CI: 0.9-6.1, p=0.07; Figure 1), this did not cross the threshold of statistial significance. Among patients diagnosed in the pre-novel agent era who developed RT (n=69), CLL treatment prior to RT included: none, n=19 (28%); chemoimmunotherapy only, n=36 (52%); and novel agent, n=14 (20%; includes 11 treated with prior chemoimmunotherapy also). In contrast, among patients diagnosed in the novel agent era who developed RT (n=13), CLL treatment prior to RT included: none, n=8 (62%); and novel agent, n=5 (38%). CONCLUSIONS Patients who received CLL/SLL directed treatment appear to have a lower risk of RT in the novel agent era. This may be driven by the fact that none of the patients who developed RT in the novel agent era received chemoimmunotherapy. Whether novel agent use for CLL/SLL suppresses the development of RT or avoids the risk associated with cytotoxic chemotherapy-induced clonal evolution requires further study. Although limited by length of follow-up, our findings challenge the notion that RT incidence will increase in parallel with CLL patients living longer with novel agent treatments.