Ibrutinib Therapy Research Articles

Discontinuation Due to Toxicity Limits Treatment Duration of BTK Inhibitors in Non-Hodgkin Lymphoma

Background: Although clinical trial data exist describing the adverse effects of Bruton's tyrosine kinase inhibitors (BTKi)s, the patient experience outside clinical trials, including differences among agents is less well-described. We evaluated the selection criteria, efficacy and toxicities related to the use of BTKi at our site.Methods: A retrospective patient chart review was used to collect data from patients treated with one or more BTKi. Demographics, prior therapies, duration of treatment, response to treatment, and incidence and severity of pre-determined toxicities of interest were collected for each patient. Descriptive statistics for each variable were reported. Association between variables of interest and the study cohort were examined using ANOVA for categorical variables and Pearson correlation coefficient for continuous variables. Survival and duration of treatment were estimated using the Kaplan-Meier method according to first novel agent. Survival analysis for each novel agent was conducted using Cox proportional hazards models and log-rank tests.Results: One hundred forty patients were included in this study, including 94 patients with CLL, 24 with MCL, and 22 with other NHL subtypes. One hundred thirteen patients received ibrutinib, while 17 patients received acalabrutinib (n=16) or zanubrutinib (n=1), which were combined in the statistical analysis. Of patients receiving ibrutinib, 69% reported at least one toxicity event during the duration of their treatment. Across all patients who received ibrutinib, 35 individuals did not report a toxicity, 48 individuals reported one toxicity, and 30 individuals reported two or more toxicities. Among the 78 patients who experienced at least one toxicity, 41 (52.5%) discontinued the medication due to these adverse effects, most commonly cytopenias (n=9), diarrhea (n=8), and fatigue (n=9). 57% of patients who reported diarrhea, 36% of patients who reported cytopenias, and 33% of patients who reported fatigue discontinued therapy due to that reported AE. In total, 60/113 patients receiving ibrutinib discontinued therapy, including 40 (66%) due to toxicity and 14 (23.3%) due to disease progression. The remaining patients discontinued therapy due to voluntary choice of new therapy or due to personal decision to stop treatment. Patients remained on ibrutinib therapy for a median duration of 40 months. 53% of patients taking zanabrutinib or acalabrutinib reported at least 1 toxicity, but only 11.7% of patients discontinued therapy for any reason. All patients who discontinued zanubrutinib/acalabrutinib therapy did so due to toxicity, with no patients ceasing therapy due to disease progression. Because only 2 of 17 patients discontinued zanubrutinib/acalabrutinib treatment, a raw median duration of treatment was calculated to be 5 months. 12.4% of patients taking ibrutinib experienced a gastrointestinal toxicity, whereas 5.9% of patients taking acalabrutinib/zanubrutinib experienced a gastrointestinal toxicity (Table 1). Additionally, 8% of individuals taking ibrutinib reported a musculoskeletal toxicity, while no acalabrutinib/zanubrutinib patients reported a musculoskeletal toxicity. There were no statistically significant differences in frequency of toxicities encountered, possibly due to study size. Other toxicities common to all analyzed BTK inhibitors included hematological, cardiovascular, and constitutional adverse effects with no significant difference between agents.Conclusions: We identified that >1/3 of individuals taking BTK inhibitors are stopping therapy prematurely due to toxicity related outcomes rather than due to disease progression. Our findings suggest that proactive identification and management of adverse effects could prolong therapy duration and provide better outcomes for patients. Strategies to personalize therapy selection to limit therapy discontinuation due to toxicity are needed as additional targeted agents are developed. [Display omitted] DisclosuresValla: BeiGene: Speakers Bureau. Cohen: Janssen, Adaptive, Aptitude Health, BeiGene, Cellectar, Adicet, Loxo/Lilly, AStra ZenecaKite/Gilead: Consultancy; Genentech, Takeda, BMS/Celgene, BioInvent, LAM, Astra Zeneca, Novartis, Loxo/Lilly: Research Funding.

Dynamic Reprogramming and Evolution Associated with Sequential Resistance to Ibrutinib and CAR T Therapy in Mantle Cell Lymphoma

IntroductionFDA approval for CD19 chimeric antigen receptor (CAR) T therapy with Brexucabtagene Autoleucel (BA) for relapsed mantle cell lymphoma (MCL) is a milestone advance. However, most patients relapsed after Bruton's tyrosine kinase (BTK) inhibitor ibrutinib therapy and CAR T therapy, making it urgent and essential to uncover the underlying mechanisms that govern resistance to ibrutinib and BA, as well as potential therapeutic targets.MethodTwo cohorts of primary patient samples were longitudinally collected at pre- and post-ibrutinib therapy (cohort 1, n = 12, samples = 28) or at pre- and post-BA therapy (cohort 2, n = 15, samples = 39) and subject to single-cell RNA sequencing (Figure 1A). Two healthy PBMC samples were included as normal controls. All 67 patient samples were divided into four major groups based on clinical outcomes: samples with fast response to ibrutinib (IBN-S), samples with slow response (IBN-Slow), samples with resistance (IBN-R), and samples with dual resistance to ibrutinib and BA (Dual). Data was integrated across cohorts and experimental batches. In-silico isolation of B cells was followed by differential gene expression analysis using a mixed model with random effect accounting for inter-patient variation. Gene Set Enrichment Analysis (GSEA) was performed to link clinical outcomes to dysregulated cancer hallmarks. Trajectory analysis further modeled the sequential changes resulting in different clinical outcomes. Copy number variation (CNV) analysis was performed to infer chromosomal aberrations.ResultsA high degree of transcriptomic heterogeneity was observed in tumor cells among patients within the same or across different clinical outcomes. Differential gene expression analysis revealed a set of outcome-specific genes across all patients. A list of 37 genes was consistently altered between Dual and IBN-R samples across both cohorts (FDR<0.1). The co-enrichment of OXPHOS and MYC pathways was linked to both ibrutinib resistance and BA resistance in an additive manner. Progressive co-enrichment was detected in different contrasts, including IBN-Slow vs IBN-S, IBN-R vs IBN-Slow plus IBN-S, and Dual vs IBN-R (Figure 1B, FDR<0.05).To capture the transitions of biological processes between different clinical outcomes, we performed trajectory analysis. The major trajectory stemmed from normal to IBN-S samples, then branched into IBN-Slow and IBN-R/Dual, which further branched into IBN-R and Dual (Figure 1C). A list of differentially expressed genes near the bifurcation point of trajectories (IBN-R/Dual) was identified (adjusted p-value < 2e-16) .To further understand the evolution associated with therapeutic resistance at the genomic level, we conducted the CNV analysis. We then quantified the genome instability score using chromosomal aberrations and observed a significant positive association with tumor aggressiveness (ANOVA test, p-value < 2e-16). Dual samples had the highest score, followed by IBN-R, IBN-Slow, and IBN-S (Figure 1D). Of note, chr22p gain was exclusive to the CAR T-resistant samples (4 out of 6), with specific aberrations in immunoglobulin lambda variable (IGLV) and constant (IGLC) genes, suggesting its association with BA resistance. Together with previously identified DEGs, targetable molecules are under active investigation for therapeutic development to overcome BA resistance.ConclusionIn this study, we found co-enrichment of the OXPHOS and MYC pathways in each resistant cohort, suggesting their predominant role in ibrutinib resistance and BA resistance. Trajectory analysis detected genes differentially expressed at the branch point, which may represent novel early drivers of therapeutic resistance and disease progression. Acquired genome instability is positively correlated with tumor aggressiveness. The exclusive chr22p gain and immunoglobulin lambda alterations in Dual samples may suggest novel therapeutic targets to overcome the resistance for relapsed MCL patients. Collectively, our findings gained novel insight into the underlying mechanisms of resistance to ibrutinib and BA, as well as therapeutic vulnerabilities that can be targeted to overcome resistance. [Display omitted] DisclosuresJain: Kite: Consultancy; Lilly: Membership on an entity's Board of Directors or advisory committees. Wang: Hebei Cancer Prevention Federation: Honoraria; Dava Oncology: Honoraria; Genentech: Consultancy; Bayer Healthcare: Consultancy; Clinical Care Options: Honoraria; Kite Pharma: Consultancy, Honoraria, Research Funding; Imedex: Honoraria; Janssen: Consultancy, Honoraria, Research Funding; InnoCare: Consultancy, Research Funding; Miltenyi Biomedicine GmbH: Consultancy, Honoraria; Mumbai Hematology Group: Honoraria; DTRM Biopharma (Cayman) Limited: Consultancy; Epizyme: Consultancy, Honoraria; The First Afflicted Hospital of Zhejiang University: Honoraria; VelosBio: Consultancy, Research Funding; CStone: Consultancy; BGICS: Honoraria; OMI: Honoraria; Anticancer Association: Honoraria; Acerta Pharma: Consultancy, Honoraria, Research Funding; CAHON: Honoraria; AstraZeneca: Consultancy, Honoraria, Research Funding; Chinese Medical Association: Honoraria; BeiGene: Consultancy, Honoraria, Research Funding; Moffit Cancer Center: Honoraria; Newbridge Pharmaceuticals: Honoraria; Scripps: Honoraria; Juno: Consultancy, Research Funding; Loxo Oncology: Consultancy, Research Funding; Oncternal: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; BioInvent: Research Funding; Celgene: Research Funding; Lilly: Research Funding; Molecular Templates: Research Funding; Physicians Education Resources (PER): Honoraria.

A CASE REPORT OF IBRUTINIB-INDUCED PNEUMONITIS

TOPIC: Lung Pathology TYPE: Medical Student/Resident Case Reports INTRODUCTION: Ibrutinib irreversibly inhibits Bruton's tyrosine kinase, an essential component of B-cell receptor signaling, leading to diminished proliferation and survival of malignant B-cells. Ibrutinib is used to treat leukemias and lymphomas, including chronic lymphocytic leukemia (CLL). Several complications are associated with ibrutinib, below describes a case of ibrutinib induced pneumonitis. CASE PRESENTATION: 64-year-old female recently diagnosed with CLL and started on ibrutinib therapy. Two months later, patient was admitted for progressive dyspnea and nonproductive cough. Initial work-up showed hypoxia, lymphocytic leukocytosis, negative COVID and respiratory viral pathogen panel (RVP). Computed tomography (CT) of chest showed new bilateral ground-glass opacities compared to CT scan three months earlier. She was initially treated with ceftriaxone and azithromycin. Patient had worsening respiratory status and required intubation on day four. Patient did not improve with several antibiotics and antifungals. But given history and borderline elevated beta-D-glucan, she underwent bronchoscopy due to concern for fungal infection. All studies including tuberculosis, histoplasma, aspergillus, coccidioides, blastomyces, pneumocystis jiroveci, fungal and bacterial cultures were negative. All antimicrobials were stopped. Patient had spontaneous pneumothoraxes on hospital day 13 and 15 requiring left needle decompression and bilateral chest tube placement. A sputum culture was repeated which grew few multi-drug resistant pseudomonas. She was treated with 7-day course of meropenem without improvement. Repeat workup showed bilateral ground-glass opacities, negative COVID, RVP, and bronchoscopy with negative fungal antigens, bacterial and fungal cultures. Given concern for ibrutinib induced pneumonitis, steroids were started with subsequent weaning from ventilator support to room air. DISCUSSION: Pneumonitis and pneumothorax are rare complications of ibrutinib therapy. The new ground-glass opacities, not present on imaging prior to starting ibrutinib, dyspnea and hypoxia, no prior lung disease, and no other new medications, is concerning for ibrutinib associated pneumonitis. Infection did not cause the opacities, both extensive infectious workups were unremarkable. The pseudomonas sputum culture was likely colonization from prolonged intubation, as she was afebrile, had stable leukocytosis, and treatment did not change respiratory status. Patient also had spontaneous pneumothoraces on lung protective ventilation. She has no history of pneumothorax, nor underlying condition that would lead to pneumothorax. In addition, oxygenation improved after starting steroids. She was weaned from ventilator support to room air, further supporting ibrutinib associated pneumonitis. CONCLUSIONS: Pneumonitis is a rare, notable complication of ibrutinib therapy. REFERENCE #1: Rai, K. R., MD, & Stilgenbauer, S., MD. (2021, January 07). Selection of Initial Therapy For Symptomatic or Advanced Chronic Lymphocytic Leukemia. Retrieved from https://www.uptodate.com/contents/selection-of-initial-therapy-for-symptomatic-or-advanced-chronic-lymphocytic-leukemia?search=ibrutinib pneumonitissIbrutinib-induced pneumonitis in patients with chronic lymphocytic leukemia. Blood 2016;127 (8): 1064–1067. doi: https://doi.org/10.1182/blood-2015-12-686873 DISCLOSURES: No relevant relationships by Tyler Cooper, source=Web Response No relevant relationships by Lauren Sesemann, source=Web Response

GET THE MUNKII OFF YOUR BACK! A RARE BLACK MOLD CAPRONIA MUNKII CAUSING INVASIVE FUNGAL INFECTION IN AN IMMUNOCOMPROMISED INDIVIDUAL

TOPIC: Chest Infections TYPE: Fellow Case Reports INTRODUCTION: Individuals receiving chemotherapy or undergoing transplantation are increasingly susceptible to invasive fungal infections. They are commonly caused by opportunistic pathogens like Aspergillus and Candida and are associated with high morbidity and mortality. Such individuals are also susceptible to invasive mold infections. We present a rare case of a black mold Capronia munkii causing cavitary lung lesions in a patient with NHL. CASE PRESENTATION: A 65-year-old female with non-Hodgkin's Lymphoma, CNS lymphoma treated with chemotherapy and autologous stem cell transplant five years ago, had progression of disease last year. She began Ibrutinib therapy for her lymphoma. She was admitted to the hospital for altered mental status due to progression of CNS disease. She developed worsening respiratory failure during hospitalization requiring intubation and mechanical ventilation. She was empirically treated with intravenous vancomycin and piperacillin-tazobactam. Her initial infectious workup and lumbar puncture was negative. Computed tomography (CT) of her chest showed new diffuse ground glass opacities.Bronchial wash was notable for black mold Capronia munkii. She was started on Voriconazole and Amphotericin B. Repeat CT chest showed improving opacities with increasing apical cystic lesions. Respiratory failure can be attributed to mold infection in the lung, immunotherapy-induced pneumonitis and organizing pneumonia. After multiple failed spontaneous breathing trials and septic shock necessitating vasopressors, she was transitioned to comfort care and subsequently expired. DISCUSSION: Capronia munkii is a saprotrophic yeast commonly found on decaying plant matter. There is a lack of clinical information on this mold in literature. It is closely related phylogenetically to Exophiala dermatides which is a neurotrophic black mold. It typically causes a non-specific granulomatous inflammatory response. The host responses are highly variable, and include pulmonary cyst formation and tissue necrosis. The patient's immunosuppression and cystic lesions on CT scan make invasive black mold infection likely. Biopsy of the cavitary lesions to determine the presence of mold would have been confirmatory. The lack of response to anti-fungal treatment reiterates the high mortality associated with this rare infection. CONCLUSIONS: Invasive fungal infections have become more prevalent due to increasing number of individuals undergoing transplantation or receiving aggressive immunosuppression and chemotherapy. Early diagnosis and prompt treatment of uncommon pathogens like black mold with appropriate azole and caspofungin antibiotics is essential to prevent poor outcomes. Newer molecular techniques such as 18S ribosomal RNA PCR and genome sequencing have led to improved diagnosis.Treatment algorithms should be adapted to accommodate changing epidemiologies and anti-fungal drug resistance patterns. REFERENCE #1: Bassetti M, Bouza E. Invasive mould infections in the ICU setting: complexities and solutions. J Antimicrob Chemother. 2017 Mar 1;72(suppl_1):i39-i47. doi: 10.1093/jac/dkx032. PMID: 28355466. REFERENCE #2: Enoch DA, Yang H, Aliyu SH, Micallef C. The Changing Epidemiology of Invasive Fungal Infections. Methods Mol Biol. 2017;1508:17-65. doi: 10.1007/978-1-4939-6515-1_2. PMID: 27837497. REFERENCE #3: Badiee P, Hashemizadeh Z. Opportunistic invasive fungal infections: diagnosis & clinical management. Indian J Med Res. 2014 Feb;139(2):195-204. PMID: 24718393; PMCID: PMC4001330. DISCLOSURES: No relevant relationships by Padmastuti Akella, source=Web Response No relevant relationships by Saira Imran, source=Web Response No relevant relationships by Shashank Nuguru, source=Web Response

Frontline Treatment of the Young, Fit Patient with CLL: A Canadian Perspective.

From a Canadian perspective, there has been a limited discussion on the frontline management of young, fit patients with chronic lymphocytic leukemia (CLL). The prevalence of this population ranges between 2 and 22 per 100,000 persons in Canada and varies by region. Until recently, fixed-duration fludarabine-based chemoimmunotherapy (CIT) was the primary treatment option in Canada for this patient population. The ECOG1912 trial has since demonstrated that ibrutinib and rituximab therapy are as effective as fludarabine-cyclophosphamide-rituximab (FCR) in this population. The ALLIANCE trial showed that rituximab added no incremental benefit to ibrutinib. Canadian payors and physicians adopted ibrutinib monotherapy as the CLL standard of care, even in the young, fit population, although frontline ibrutinib therapy is often reimbursed by provincial public drug plans only in patients with high-risk disease or those who are unfit to receive fludarabine. Young, fit patients with CLL and their physicians may now choose between continuous ibrutinib monotherapy and fixed-duration CIT with FCR. Factors affecting this choice include patient preference and the short- and long-term toxicity profiles of both regimens, and a risk-based algorithm is provided. As new continuous-therapy options enter the market, all treatment choices present benefits and risks that must be communicated to the patient.

Efficacy and Safety of Ibrutinib Therapy in Patients with Chronic Lymphocytic Leukemia: Retrospective Analysis of Real-Life Data

Objective:This study aimed to retrospectively evaluate the efficacy, safety, and survival outcome of single-agent ibrutinib therapy in chronic lymphocytic leukemia patients.Materials and Methods:A total of 136 patients (mean age ± standard deviation: 64.6±10.3 years, 66.9% males) who had received at least one dose of ibrutinib were included in this retrospective multicenter, noninterventional hospital-registry study conducted at 33 centers across Turkey. Data on patient demographics, baseline characteristics, laboratory findings, and leukemia-cell cytogenetics were retrieved. Treatment response, survival outcome including overall survival (OS) and progression-free survival (PFS), and safety data were analyzed.Results:Overall, 36.7% of patients were categorized as Eastern Cooperative Oncology Group (ECOG) class 2-3, while 44.9% were in Rai stage 4. Fluorescence in situ hybridization revealed the presence of del(17p) in 39.8% of the patients. Patients received a median of 2.0 (range: 0-7) lines of pre-ibrutinib therapy. Median duration of therapy was 8.8 months (range: 0.4-58.0 months). The 1-year PFS and OS rates were 82.2% and 84.6%, respectively, while median PFS time was 30.0 (standard error, 95% confidence interval: 5.1, 20.0-40.0) months and median OS time was 37.9 (3.2, 31.5-44.2) months. Treatment response (complete or partial response), PFS time, and OS time were better with 0-2 lines versus 3-7 lines of prior therapy (p<0.001, p=0.001, and p<0.001, respectively), with ECOG class 0-1 versus class 2-3 (p=0.006, p=0.011, and p=0.001, respectively), and with Rai stage 0-2 versus 3-4 (p=0.002, p=0.001, and p=0.002, respectively). No significant difference was noted in treatment response rates or survival outcome with respect to the presence of comorbidity, bulky disease, or del(17p). While 176 adverse events (AEs) were reported in 74 (54.4%) patients, 46 of those 176 AEs were grade 3-4, including pneumonia (n=12), neutropenia (n=11), anemia (n=5), thrombocytopenia (n=5), and fever (n=5).Conclusion:This real-life analysis confirms the favorable efficacy and safety profile of long-term ibrutinib treatment while emphasizing the potential adverse impacts of poorer ECOG performance status, heavy treatment prior to ibrutinib, and advanced Rai stage on patient compliance, treatment response, and survival outcomes.

B-PO03-172 PREDICTORS OF IBRUTINIB TREATMENT INTERRUPTION SECONDARY TO ARRHYTHMIAS

Ibrutinib, a tyrosine kinase inhibitor (TKI), used in chronic lymphocytic leukemia, has been associated with increased incidence of atrial fibrillation (AF); with known treatment interruptions due to intractable AF episodes. The details of arrhythmic episodes that are associated with treatment interruptions remain unclear. To determine predictors of ibrutinib treatment interruption secondary to arrhythmias. A retrospective data analysis at a single center using electronic medical records database search tools and individual chart review was conducted to identify consecutive patients who had holter monitors while on ibrutinib therapy. 72 patients who had holter monitors while on ibrutinib therapy were included in analysis. Mean age was 76.9±9.9 years, 25% were female and the average duration of ibrutinib treatment was 32.3±22 months. Ibrutinib treatment was interrupted in n=18 (25%) of patients due to arrhythmias and n=9 (12.5%) were initiated on anti-arrhythmic medications due to arrhythmias secondary to ibrutinib therapy. Interruptions in ibrutinib therapy were associated with >1% PAC burden on holter monitor while on ibrutinib therapy (p=0.002) and a prior history of VT (p=0.005); but not with >1% PVC burden (p=0.285), presence of SVT (p=0.747), AF (p=0.292) or NSVT (p=0.147) on holter monitor. Patients in whom ibrutinib was held for arrhythmias were more likely to be seen by an electrophysiology specialist (p=0.041), along with patients on ibrutinib whose holter monitors showed NSVT (p=0.011). Female patients were referred to a cardiac specialist less than their male counterparts (p=0.051). In this large dataset of holter monitors on patients treated with ibrutinib, interruptions in TKI therapy correlated with certain arrhythmia patterns that could predate intractable arrhythmias and drug cessation in the future; which can help identify patients who may benefit from closer monitoring.

Five year experience in ibrutinib therapy for relapsed and refractory mantle cell lymphoma in real world Russian clinical practice

Mantle cell lymphoma (MCL) is a rare and clinically aggressive lymphoma subtype. Current approaches have greatly improved patients outcomes, but relapse is inevitable. In phase IIIII clinical trials, ibrutinib has shown significant activity in patients with relapsed or refractory (R/R) MCL. To assess efficacy and toxicity of ibrutinib monotherapy in patients with R/R MCL in routine practice outside of clinical trials. The study enrolled patients with confirmed R/R MCL who had received at least one line of previous chemotherapy. ECOG 24, cytopenia, infectious complications, hemorrhagic syndrome were not exclusion criteria. Patients received daily oral ibrutinib 560 mg until progression or unacceptable toxicity. From May 2015 to September 2020 ibrutinib therapy was started in 106 patients with R/R MCL in 16 regions of Russia. The median age was 66 years; ECOG2 18%, blastoid variant (or Ki6740% or WBC50109/l) 43%. The median number of previous treatment lines was 2 (111). The ORR was 78.4% (CRR 27.4%). The median PFS was 13.6 months and OS 23.2 months. In the blastoid group the median PFS was 4.4 months vs 36.5 months in the alternative group (p0.001), the median OS 9.0 vs 41.0 (p=0.001). The median OS of patients after progression on ibrutinib was 3.2 months. The common complications are hemorrhages (63%), diarrhea (62%), myalgia and muscle cramps (60%), infections (31%), skin and nail toxicity 15%, arrhythmia 8%. None of recipients had to completely discontinue ibrutinib therapy due to complications. Ibrutinib is effective and well tolerated in routine practice of R/R MCL treatment and our results are consistent with international clinical trials. The favorable toxicity profile and the high response rate made it possible to prescribe ibrutinib in severe somatic status, cytopenia, and even in the presence of infectious complications.

Alternative strategies for optimizing treatment of chronic lymphocytic leukemia with complex clonal architecture

In silico simulation of pre-clinical and clinical data may accelerate pre-clinical and clinical trial advances, leading to benefits for therapeutic outcomes, toxicity and cost savings. Combining this with clonal architecture data may permit truly personalized therapy. Chronic lymphocytic leukemia (CLL) exhibits clonal diversity, evolution and selection, spontaneously and under treatment pressure. We apply a dynamic simulation model to published CLL clonal architecture data to explore alternative therapeutic strategies, focusing on BTK inhibition. By deriving parameters of clonal growth and death behavior we model continuous vs time-limited ibrutinib therapy, and find that, despite persistence of disease, time to clinical progression may not differ. This is a testable hypothesis. We model IgVH-mutated CLL vs unmutated CLL by varying proliferation and find, based on the limited available data about clonal dynamics after such therapy, that there are differences predicted in response to anti-CD20 efficacy. These models can suggest potential clinical trials, and also indicate what additional data are needed to improve predictions. Ongoing work will expand modeling to agents such as venetoclax and to T cell therapies.

Secondary Hypogammaglobulinemia in Patients with Chronic Lymphocytic Leukemia Receiving Ibrutinib Therapy.

The online version contains supplementary material available at 10.1007/s12288-021-01466-1.

Patient-Reported Symptoms during Ibrutinib Holds: A Withdrawal Syndrome

Background:The Bruton tyrosine kinase (BTK) inhibitor ibrutinib recently became the first approved therapy for patients with symptomatic Waldenström macroglobulinemia (WM). The management of ibrutinib-related toxicities, such as bleeding and others, are often managed with temporary interruption of therapy. We observed that some WM patients who held ibrutinib developed symptoms during the time they were holding ibrutinib, which then resolved promptly after ibrutinib reinitiation. Our study aims at describing this “ibrutinib withdrawal” phenomenon.Methods: We identified patients seen at our institution between May 2012 and April 2017 who met clinicopathological criteria for WM, and received ibrutinib therapy. Medical files were manually reviewed to identify patients who reported new-onset symptoms occurring during a temporary hold of ibrutinib therapy. Pertinent clinical data were gathered. Patient characteristics are summarized descriptively. Univariate association with withdrawal symptoms was evaluated with logistic regression models.Results: A total of 189 patients with WM who started ibrutinib were identified; 100 patients (53%) have not held ibrutinib, and 89 (47%) held ibrutinib at some point during therapy. The median time on ibrutinib therapy in patients who held ibrutinib was 23 months (95% CI 13-30 months) and 10 months (95% CI 7-12 months) in patients who did not hold ibrutinib. There were no differences between the patients who held and did not hold ibrutinib with regards to age at WM diagnosis, age at ibrutinib initiation, sex, hemoglobin, platelet count, beta-2-microglobulin (B2M), serum IgM, bone marrow involvement, CXCR4 status, prior treatment and time between WM diagnosis and ibrutinib initiation (p≥0.05 for all factors). From the patients who held ibrutinib, 69 (78%) did not experience withdrawal symptoms and 20 (22%) did. Of the patients who experienced withdrawal symptoms, 17 (85%) were receiving ibrutinib in the relapsed/refractory setting. All patients were holding ibrutinib for the first time since treatment initiation. The median drug hold length was 7 days (range 3-33 days). Reasons for holding ibrutinib included: procedure/surgery (n=12; 60%), toxicity (n=6; 30%), drug interaction (n=1; 5%), and patient choice (n=1; 5%). The median time to symptom development was 2 days (range 0-5 days) from the start of the drug hold. Patient-reported symptoms included: fever (n=16; 80%), body aches (n=6; 30%), chills (n=5; 20%), night sweats (n=5; 20%), headache (n=4; 20%), fatigue (n=2; 10%), arthralgias (n=2; 10%), and weakness (n=1; 5%). There were no differences between patients who became symptomatic and remained asymptomatic during ibrutinib hold with regards to age at WM diagnosis, age at ibrutinib initiation, sex, hemoglobin, platelet count, B2M, bone marrow involvement, CXCR4 status, prior treatment, time from WM diagnosis and ibrutinib initiation and time on ibrutinib (p≥0.05 for all factors). Patients with serum IgM >4,000 mg/dl had a lower proportion of withdrawal symptoms than patients with serum IgM <4,000 mg/dl (9% vs. 30%; p=0.02). The rates of very good partial response (VGPR), partial response (PR), minor response (MR) and no response (NR) to ibrutinib were 16% (n=13), 57% (n=108), 22% (n=41) and 5% (n=9), respectively. No withdrawal symptoms were reported in patients with MR or NR. The proportion of patients with withdrawal symptoms was higher in patients who achieved VGPR (46%) than in patients who achieved PR (25%). Four patients with fever were admitted to the hospital; no infectious etiology was identified. All patients reported resolution of symptoms the same day ibrutinib was restarted following the drug hold. Nine patients had subsequent drug holds, and reported recurrence of the same symptoms during the hold period. Two patients known to develop these symptoms were treated with corticosteroids during a subsequent hold and reported symptomatic relief.Conclusion: We describe patient-reported symptoms that develop in about 20% of WM patients who held ibrutinib therapy. The rate of withdrawal symptoms is lower in patients who started ibrutinib with IgM levels >4,000 mg/dl (9%), and higher in patients who had achieved VGPR on ibrutinib (46%). Such symptoms ensue within 2 days of hold and resolve rapidly following reinitiation of therapy. Clinicians should be aware of this phenomenon which may represent an ibrutinib withdrawal syndrome. DisclosuresCastillo:Millennium: Research Funding; Abbvie: Research Funding; Pharmacyclics: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Treon:Pharmacyclics: Consultancy, Research Funding.

Dissection of Clonal Evolution By Temporal Mutation Profiling in Chronic Lymphocytic Leukemia Patients Treated with Ibrutinib

Introduction: The irreversible Bruton tyrosine kinase (BTK) inhibitor ibrutinib is changing the paradigm of the treatment of chronic lymphocytic leukemia (CLL) with remarkable outcomes in first line as well as in relapsed CLL, including high risk patients with TP53 aberration. While the majority of patients demonstrate durable responses, with a median follow up of 3 years, approximately 18% of them develop resistance and relapse. Mutations in the BTK and PLCG2 genes emerged as predominant mechanisms conferring secondary ibrutinib resistance with BTK and/or PLCG2 mutations detected in the majority of resistant patients, often even 10 months before the clinical relapse. Given the very poor outcome of patients discontinuing ibrutinib, comprehensive understanding of the mechanisms of ibrutinib resistance and changes in the clonal architecture induced by the selective pressure of the drug are of major clinical importance. To dissect the clonal evolution in the context of all relevant mutation targets in CLL, we performed a temporal mutation profiling of 31 genes in paired pre- and post-treatment samples of patients receiving ibrutinib therapy.Methods: Sequential samples from 18 patients treated with single-agent ibrutinib were included in this study. Pre-treatment peripheral blood samples were available in all patients, with post-treatment samples at 18 months for 6 patients, at 12 months for 7 patients, at 8 months for 3 patients and at 3 months for 2 patients, with a median follow up of 12 months. Targeted deep NGS analysis of 31 recurrently mutated target genes, including ATM, BCOR, BIRC3, BRAF, BTK, CHD2, DDX3X, EGR2, EIF2A, EP300, FBXW7, HIST1H1E, IGLL5, KLHL6, KMT2D, LRP1B, MAPK1, MED12, MGA, MYD88, NFKBIE, NOTCH1, PLCG2, POT1, RIPK1, RPS15, SAMHD1, SF3B1, TP53, XPO1 and ZMYM3 was performed using the TruSeq Custom Amplicon approach (Illumina) on genomic DNA specimens extracted from peripheral blood mononuclear cells. Variant calling was performed using the VariantStudio3.0 application (Illumina) and only variants supported with more than 100 mutant reads were considered. Our cohort represented a heavily pretreated patient group with a median of 2.5 (range: 1-5) lines of prior therapies.Results: The ultra-deep NGS analysis revealed a total of 473 somatic mutations in the 18 paired samples with a median allelic depth of 25.550x across the 31 genes analyzed. The post-treatment samples carried a considerably higher number of mutations compared to the pre-treatment samples (114 vs 359 mutations) with more than half of the variants representing subclonal alterations with variant allele frequencies (VAF) of <10%. The most frequently mutated genes at baseline included TP53 (50%) , NOTCH1 (50%) and POT1 (28%) with similarly high mutation frequencies in the post-treatment samples. MYD88, BIRC3 and SF3B1 mutations were enriched in the post-ibrutinib samples with mutation frequencies of 11% vs 33%, 11% vs 39% and 11% vs 50%, respectively. Interestingly, XPO1 mutations emerged only in the post-treatment samples of five (28%) patients. As for the BTK and PLCG2 mutations, none of the pre-treatment samples carried a mutation in either of these genes, however, we detected emerging subclonal BTK and PLCG2 mutations (with VAFs between 1.5% and 11%) in 28% (5/18) and 33% (6/18) of the post-treatment samples, respectively. A subset of cases harbored multiple mutations in both genes with some of these representing novel BTK and PLCG2 mutations affecting previously unreported amino acid residues. Scrutiny of the clonal evolution revealed that all individual cases were characterized by almost unique combinations of mutations as well as patterns of emerging and disappearing mutant subclones upon the selective pressure of ibrutinib.Conclusions: The ultra-deep NGS analysis performed on paired samples of CLL patients treated with ibrutinib provided a significant insight into the mutational repertoire as well as subclonal dynamics of the leukemic compartment. Furthermore, it has revealed a profound subclonal heterogeneity that seems to be further enhanced by ibrutinib therapy, as demonstrated by a higher frequency of subclonal variants in the post-treatment samples. The clinical significance and the potential role of the novel BTK and PLCG2 variants identified in our study will require a longer follow up time, as currently all patients harboring these subclonal variants are still on ibrutinib therapy. DisclosuresNo relevant conflicts of interest to declare.

Median 3.5-Year Follow-up of Ibrutinib Treatment in Patients with Relapsed/Refractory Mantle Cell Lymphoma: A Pooled Analysis

Median 3.5-Year Follow-up of Ibrutinib Treatment in Patients with Relapsed/Refractory Mantle Cell Lymphoma: A Pooled Analysis

Disease Progression on Ibrutinib Therapy Is Associated with a Poor Clinical Outcome in Chronic Lymphocytic Leukemia (CLL) Patients Managed in Standard Clinical Practice

Introduction: Ibrutinib is an irreversible Bruton Tyrosine Kinase (BTK) inhibitor that has shown efficacy in the treatment of CLL as a front-line therapy or in patients with relapse/refractory (RR) disease. Anecdotally, accelerated disease progression and refractoriness to subsequent therapies in CLL or other B-cell malignancies patients treated with ibrutinib has been observed. In our present contribution, we studied in a real-world patient population the clinical outcome of CLL patients treated with ibrutinib who discontinued therapy. Methods: We conducted a comprehensive retrospective analysis on CLL patients receiving ibrutinib at our Institute. Demographic characteristics, response to subsequent therapies, and results of FISH analysis were obtained. Correlation between clinical outcomes and status on ibrutinib therapy (responding, progressing, or discontinuing due to toxicity) was performed. Statistical analysis was carried out in SPSS v20. Chi Square, Fisher's exact test were used to compare categorical data, Kaplan Meier and Log rank tests for time to event analysis and Cox regression for univariate analysis. Results: A total of 70 CLL patients treated with ibrutinib were followed for a median period of 19.4 mo [ range 0.3 - 41.3]. Sixty-three patients had RR CLL and 7 received ibrutinib as frontline therapy. Our patients had a median age of 67.9 years (46 - 92), a majority had advanced stage disease (Rai stage 3 - 31.4%, Rai stage 4 - 41.4%). Median number of prior treatments was 2 (range 0-7). Overall response rate (ORR) to ibrutinib was 52.8% (complete response [CR] - 11.4%, partial response [PR] - 41.4%]. Additionally, stable disease [SD] was present in 25.7% leading to a Clinical Benefit Rate (CBR) of 78.5%. A total of 25 (38%) patients discontinued therapy. Reasons for discontinuation included progressive disease (PD) in 13 (52%) (5 with Richter's transformation [RT]), drug toxicity (DT) in 7 (28%), and other reasons in 5 (20%) patients. DTs included atrial fibrillation (n=2), sepsis (n=2), pneumonia (n=1), congestive heart failure (n=1) and fatigue (n=1). Other reasons for discontinuation were other terminal cancer (n=2), patient preference, alcoholism and insurance issues. Univariate analysis showed an increased risk of discontinuation associated with del(13q) (HR 1.56, 95%CI 0.7-3.7, p=0 .32), ATM deletion (HR 1.32, 95%CI 0.5-3.4, p=0 .57), Unmutated IgH (HR 3.5, 0.5-27.3, p=0 .23) though none reached statistical significance. We did not observe an increased risk of discontinuation in patients with del(17p) (HR 0.80, 95%CI 0.3-2.7, p=0 .72). Cytogenetic data after ibrutinib discontinuation was available in 12 patients and showed new onset del(13q) (n= 3), del(17p) (n= 4) and ATM deletion (n= 1) including 1 patient who had complex cytogenetics (≥3 cytogenetic abnormalities). In patients who discontinued therapy, we observed a mortality rate of 72% (18/25) with a median overall survival (OS) of 17.8 mo (95% CI, 7.4-28.2); in comparison, median OS was not reached in patients who remained on therapy (p <0.05). A lower median OS was observed in patients who discontinued due to DT (5.9 mo, 95% CI, 3.9-8), compared to those with RT (11.5 mo, 95% CI 3.1-20), PD (18.2 mo, 95%CI 3.8-32.6) though this was not statistically significant (p= 0.117). Despite trends towards lower median OS in patients who discontinue ibrutinib, univariate analysis did not show a statistically significant association with del(13q) (HR 1.8, 95%CI 0.7-5, p=0 .248), ATM deletion (HR 1.32, 95%CI 0.5-3.9, p=0 .61), Unmutated IGH (HR 1.08, 95%CI 0.13-9, p=0 .94), and ZAP70+ (HR 1.15, 95%CI 0.36-3.64, p=0 .81). Two patients had complex cytogenetics with a median OS of 1.5 mo (HR 4.5, 95%CI 0 .9-22.4, p <0.05). Thirteen patients received subsequent therapy after ibrutinib discontinuation with idelalisib (n=3), lenalidomide (n=3), rituximab with bendamustine (n=2), R-CHOP (n=2), or other treatments (n=3). ORR to post ibrutinib therapy was 23.1% with CR in 3/13 patients (reason for discontinuation- RT - 1, other reasons- 2). Two patients had SD (both discontinued Ibrutinib for PD) leading to a CBR of 38.5%. Eight of 13 patients had PD and died during follow up period. Conclusion: Ibrutinib has good efficacy in the treatment of CLL as front-line therapy and in relapse refractory disease in a real-world setting. However, patients who discontinue therapy have poor survival outcomes and poor response to salvage therapy. DisclosuresNo relevant conflicts of interest to declare.

Serum B-Cell Maturation Antigen As a Biomarker for Chronic Lymphocytic Leukemia Treated with Ibrutinib

INTRODUCTIONEarly assessment of tumor response in chronic lymphocytic leukemia (CLL) can be difficult during ibrutinib therapy due to treatment-related lymphocytosis and concern for radiation exposure that limits the frequency of computed tomography (CT). B-cell maturation antigen (BCMA), a member of the tumor necrosis factor super family receptors, is overexpressed in CLL. In another mature B-cell malignancy, multiple myeloma, elevated serum (s) BCMA has been associated with inferior therapeutic response and survival. It was previously shown that sBCMA levels are increased in CLL and correlated with time to first treatment and overall survival. To evaluate its utility as a biomarker in the context of targeted therapy, we assessed sBCMA in CLL patients during treatment with ibrutinib. METHODSBCMA levels were measured in the serum of 46 patients enrolled on a phase 2 study of ibrutinib for CLL (NCT01500733). The following time points were evaluated: baseline, day 2, and 1, 2, 6, 12, 24, 36, 48 months (M) after starting ibrutinib, as well as at the time of progressive disease (PD), if available. sBCMA was measured using a sandwich ELISA (R&D Systems). Lymphadenopathy was measured by the sum of the product of the diameters (SPD). Signed-rank test, rank-sum test and Spearman correlation were performed to compare sBCMA between categorical and continuous variables. RESULTSBaseline disease characteristics included relapsed or refractory CLL in 15 patients (33%), 17p deletion in 31 (67%), unmutated IGHV in 33 (72%), and advanced Rai stage in 32 (70%). The median age was 67 years (range 39-81) and 26 patients (57%) were male. At baseline, the median sBCMA was 145 ng/mL (range 24-376) and significantly higher among patients with 17p deletion than those without (median 179.6 versus 75.8, P = 0.033). sBCMA was not different with respect to prior treatment status, IGHV mutation, or Rai stage. A weak correlation between sBCMA and known serologic indicators of tumor burden and activity, β2-microglobulin (r = 0.36, P = 0.02) and lactate dehydrogenase (r = 0.41, P = 0.006), was also observed.sBCMA decreased as early as day 2 (median decrease 15%, P = 0.003) and progressively decreased during the first year of ibrutinib therapy (median decrease 79%, P < 0.0001 at 12M). To assess whether early changes in sBCMA predict tumor response, we compared lymph node response at 12M between patients dichotomized by the median decrease in sBCMA at 1M. Patients with a decrease in sBCMA above the median of 65% at 1M showed a greater reduction in lymph node SPD at 12M (median reduction 84% versus 74%, P = 0.0487). However, the decrease in sBCMA at 1M was not different between patients who achieved partial remission (n = 29) and those in complete remission (n = 16) at best response per modified iwCLL criteria.Next, we retrospectively measured sBCMA in 13 patients from whom serum was collected within 3M of PD to evaluate whether it could be used to predict PD. Baseline sBCMA was not significantly different between patients who later developed PD and those who did not. Among patients who developed PD, sBCMA reached a nadir after a median of 12M on ibrutinib therapy before gradually increasing until the time of PD (median increase 153% [interquartile range, IQR 81%-314%] from nadir). The initial increase in sBCMA was observed at a median of 8.4M (range 0-20.2) before clinical progression. In contrast, patients who remained in remission experienced lesser fluctuations in sBCMA (median increase 20% [IQR 0%-43%] from nadir). The increase in sBCMA from nadir among PD cases was significantly greater than non-PD cases (P < 0.0001). CONCLUSIONsBCMA rapidly decreased during treatment with ibrutinib. Decrease in sBCMA was associated with reduction in lymphadenopathy, while an increase in sBCMA from nadir often preceded clinical PD. sBCMA represents a potential biomarker for monitoring response and detecting disease progression in CLL patients treated with ibrutinib.This research was supported by the Intramural Research Program of NHLBI. Pharmacyclics, an Abbvie company provided ibrutinib and research support. DisclosuresBerenson:OncoTracker, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Research Funding. Wiestner:Acerta Pharma: Research Funding; Pharmacyclics: Research Funding.

Autoimmune Cytopenias in Patients with Chronic Lymphocytic Leukemia Treated with Ibrutinib in Routine Clinical Practice at an Academic Medical Center

INTRODUCTIONThe effects of ibrutinib treatment on the natural history of autoimmune cytopenias (AIC) among chronic lymphocytic leukemia (CLL) patients (pts) treated on clinical trials suggests: i) a low rate of treatment-emergent (TE) AIC (~2%, Rogers, Leukemia 2016; Montillo, BCJ 2017) and ii) improved control of pre-existing AIC at the time ibrutinib is initiated with the ability to discontinue immunosuppressive therapies (~69%, Vitale, Haematologica 2016). Confirmation of these findings in CLL pts treated in routine clinical practice requires further investigation. METHODSBetween 4/2012 and 1/2017, 286 CLL pts treated with ibrutinib outside the context of a clinical trial were seen in the Division of Hematology at Mayo Clinic. The CLL Database and medical records of these pts were reviewed for details of past history of AIC and TE AIC; the diagnosis of AIC was determined by the treating physician. Cox proportional hazards regression models were used to estimate hazard ratios and 95% confidence intervals for the association of history of TE AIC with progression-free (PFS) and overall (OS) survival. Time-dependent Cox regression models were used to look at the association of TE AIC with PFS and OS. Fisher's Exact test was used to test for the association of clinical variables with TE. RESULTSAmong the 286 pts, 242 (85%) pts were treated for relapsed CLL and 44 (15%) pts for previously untreated CLL. The median age at ibrutinib start was 68 years, and 72% were males. Twenty-two percent had TP53 disruption (either del17p or TP53 mutation) and 78% had unmutated IGHV genes. We identified 37/286 (13%) pts with a history of AIC prior to ibrutinib start, including 15 pts with autoimmune hemolytic anemia (AIHA), 11 pts with immune thrombocytopenia (ITP), 5 pts with Evans syndrome, 3 pts with pure red cell aplasia (PRCA), 2 pts with autoimmune neutropenia, and 1 pt with aplastic anemia.Eleven (4%) pts developed TE AIC (including two pts with past history of AIC who developed a different AIC after ibrutinib therapy) including: AIHA (n=4), ITP (n=4), PRCA (n=1), aplastic anemia (n=1), and autoimmune neutropenia (n=1). This occurred after a median of 30 days following the initiation of ibrutinib (range, 8-325 days). Eight pts were able to continue ibrutinib after either temporarily holding ibrutinib (n=6), ibrutinib dose reduction (n=1), or no modification to ibrutinib therapy (n=1). Three of the 11 pts (ITP n=2, aplastic anemia n=1) permanently discontinued ibrutinib as a result of the AIC.Twenty-two of the 37 pts with a prior history of AIC had a remote history of AIC and were not on any AIC treatment and 15/37 pts were receiving AIC directed therapy at ibrutinib start. Among the 15 pts who were on AIC directed therapy at the time of ibrutinib initiation, 6 pts had uncontrolled disease, for which they were receiving ≥20 mg prednisone daily, and 9 pts had controlled AIC on therapy consisting of <20 mg of prednisone daily or equivalent. Five (33%) of the 15 pts on therapy were able to discontinue AIC therapy at a median of 2 months (range, 0-25), an additional 5 (33%) pts were able to reduce the dose and schedule of AIC therapy, and 3 (20%) pts continued AIC therapy with no changes. Two (14%) pts not previously on rituximab were started on the therapy due to continued steroid dependence and inability to taper off steroids. None of these 15 pts had worsening of their underlying AIC as a consequence of initiating ibrutinib therapy. See Figure 1 for temporal relationship of ibrutinib treatment.The median OS and PFS from time of ibrutinib start was not significantly different between pts with a history of AIC and those with no history of AIC (Figures 2 and 3). There was no statistically significant association between age, gender, TP53 disruption, IGHV mutation status, and history of AIC with development of TE or recurrent AIC (p-values all > 0.05). The PFS and OS were not significantly different among pts with TE AIC compared to those pts who did not develop TE AIC. CONCLUSIONIn this large retrospective cohort of ibrutinib treated CLL pts outside the context of clinical trials, we found that 1 out of every 25 pts developed TE AIC. Nonetheless, ~75% pts were still able to continue ibrutinib treatment. Improved control of AIC with discontinuation or de-escalation of AIC treatments in ~67% of pts on AIC directed therapy at ibrutinib start supports previous findings. We did not identify any risk factors for the development of TE AIC in our study. [Display omitted] DisclosuresDing:Merck: Research Funding. Kay:Gilead: Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Research Funding; Tolero Corporation: Research Funding. Shanafelt:Genentech: Research Funding; GlaxoSmithKline: Research Funding; Celgene: Research Funding; AbbVie: Research Funding; Hospira: Research Funding; Jannsen: Research Funding; Pharmacyclics: Research Funding. Parikh:AstraZeneca: Honoraria; Pharmacyclics: Honoraria; Pharmacyclics: Research Funding.

IgM and IgD Differential CLL BCRs Organization and Interaction with Co-Receptors before and during Ibrutinib Therapy

Studies of the B cell receptor (BCR) on normal B lymphocytes indicate that membrane IgM and IgD (respectively mIgM and mIgD) are organized in independent protein islands containing different BCR co-receptors that then reorganize as B cells transition from resting (CD19 and CD20 associated with IgD) to activated (CD19 and CD20 associated with IgM). In this way the signaling balance between IgM and IgD regulates B cell fate. Since BCR signaling is a key factor for chronic lymphocytic leukemia (CLL), as evinced by the efficacy of the signaling inhibitory drug ibrutinib, we decided to evaluate the membrane organization of the BCR-complex on primary CLL cells in an isotype dependent fashion.We analyzed 4 U-CLL and 4 M-CLL samples, taken before and during (4-6 weeks of) ibrutinib treatment, by imaging flow cytometry, to evaluate the tendency of mIgM or mIgD to appear in high density regions (clusters). CLL cells displayed more IgM- than IgD-containing clusters, and the spot diameters for mIgM clusters were twice as broad as those for mIgD. However, while mIgD density correlated with the number of clusters, mIgM density did not. Taken together, these data indicate that mIgM and mIgD are organized differently on CLL cell membranes.Next, we assessed the association of activating (CD19, CD20) and inhibitory (CD22, Siglec10) co-receptors with the two mIG isotypes. These findings were then correlated with in vivo birth rates measured after patients drank 2H2O. Co-localization of CD19 and CD20 with mIgM directly correlated with increased proliferation in vivo . Conversely, those patients whose CLL B cells had more CD22 co-localized with IgM than IgD had lower in vivo birth rates. Notably, there was no such correlation for co-localization of Siglec10. Thus, there was differential co-localization of IgM with CD19 and CD20 versus with CD22 and these correlated respectively positively or negatively with CLL cell growth in vivo .The mIGs of CLL cells can spontaneously self-associate and transmit a signal to the leukemic cells. This property could influence membrane organization of the two isotypes, either directly by self-binding or indirectly by repetitive signaling and subsequent cytoskeleton rearrangement. To test this, we expressed 13 different CLL BCRs in triple knockout (TKO) cells as IgMs or IgDs while maintaining their original IGHVDJ and IGLVJ structure. For BCR receptors expressed as IgM, Ca++ mobilization occurred spontaneously, without the need for an external ligand (“autonomous signaling”). In contrast, BCR receptors expressed as IgD required ligand crosslinking for signaling. Therefore, while both mIgM and mIgD BCRs are capable of signaling upon antigen engagement, only mIgM BCRs naturally self-associate and transduce a signal. This implies a constitutive, self-reorganization of the BCR clusters and co-receptor localization that differs from normal resting B cells and primes CLL activation. The self-binding strength and the quality and reorganization capacities of the induced signaling likely lead to different cellular consequences.Finally, we studied patients undergoing ibrutinib treatment. Ibrutinib significantly upregulated the sm density of IgM and downregulated IgD and CD20; however, there was little change for CD19, CD22 and Siglec10. Ibrutinib also led to even more and bigger IgM and less and smaller IgD clusters. In addition, CD22 no longer co-localized with IgM, while the level of association with IgD did not change. Finally, co-localization of CD19 and CD20 with the IgM and IgD BCRs was not significantly altered indicating: i) their organization is not dependent on Btk signaling; ii) Localization changes take place in subpopulations, but the clonal median is invariant; or iii) Changes occur at levels below our detection method.In conclusion, IgM and IgD are organized differently on CLL B cells. IgM forms bigger and more clusters than IgD, and higher CLL birth rates are found for cells with more CD19 and CD20 in proximity to IgM than IgD. Also, autonomous signaling occurs only through IgM. Thus, CLL clones exhibit a membrane organization like that of an activated B cell. Conversely, increased association of CD22 with IgM correlates with slower birth rates and a less activated cell status. Ibrutinib treatment disregulates BCR isotype organization increasing IgM cluster size and number, decreasing those with IgD and changing the relative proximity of co-receptors such as CD22. DisclosuresBarrientos:Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Janssen: Consultancy; AbbVie: Consultancy, Research Funding; Gilead: Consultancy, Research Funding.

Real-World Results on Ibrutinib in Relapsed/Refractory CLL: A 21-Month Follow-up of 95 Swedish Patients Treated in a Compassionate Use Program

Background: Ibrutinib is current standard of care for patients with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) based on phase 3 clinical trials. There is often a discrepancy between data obtained in clinical trials with strict inclusion criteria and those later obtained in routine health care. We have previously reported the 10-month follow-up of real-world results on ibrutinib in consecutive Swedish CLL patients treated in a compassionate use program (CUP) (Winqvist et al., 2016). Here we present follow-up data at 21-month follow-up with extended PFS, OS and safety.Methods: Inclusion/exclusion criteria of the CUP have been described earlier (Winqvist et al., 2016). All patients were identified for follow-up. CRFs were updated after a second round of in-depth analyses of individual patient files and data were cross-checked. Patients received 420 mg oral ibrutinib once daily until progression. Dose modifications were allowed as needed.Results: The 95 patients had a median age of 69 years, 63% had del17p/ TP53 mutation and had received a median of 3 prior therapies. 27% had PS grade 2 or 3 (Winqvist et al., 2016). The median treatment duration at this 2nd data analysis was 19.6 months (range 0.6-30.4 months) and 54 patients (57%) remained on ibrutinib therapy. The overall response rate (ORR) was 85% including 63% PR, 14% PR with lymphocytosis and 8% CR. The median PFS and OS had not yet been reached. At a median follow-up time of 21.4 months (range 1.2-30.4 months) the OS rate was 72% and the PFS rate was 65% (Fig 1 and 2).Toxicity was similar as in the first report (Winqvist et al., 2016) with 38% grade 3-4 neutropenia, 28% grade 1-2 diarrhea (1 grade 3) and 16% arthralgia /muscle pain (4 grade 3-4). Hemorrhage occurred in 52% (1 grade 5) and 13% had atrial fibrillation. Richter transformation (RT) occurred in 13% after a median time of 12.0 months (range 3.7-19.8); in contrast to another report (Woyach et al., 2016), no clearcut RT plateau was observed (Fig 3).27% of the patients have died due to RT (n=8), infection (n=5), secondary malignancy (n=4), CLL progression on therapy (n=3), CLL progression after ibrutinib cessation (n=3), congestive heart failure (n=1), subdural hematoma (n=1) and unknown (n=1).Ibrutinib was permanently stopped in 41 patients (43%). The most common reasons were RT (n=11), infection (n=7), other malignancy (n=4), allogeneic SCT (n=4), CLL progression (n=4), cutaneous AE (n=3), or drug interaction (n=2). Fifteen patients had totally 20 treatment breaks longer than 14 days (median 22 days). In contrast to others (Barr et al., 2017; Forum, 2016) we found no impact of breaks >14 days on PFS or OS.We also analyzed whether our patients would have fulfilled the inclusion criteria of the pivotal phase 3 study (RESONATE) (Byrd et al., 2014): 44% had at least 1 exclusion criteria, further supporting the real-world representativity of our cohort. However, neither ORR, PFS nor OS was significantly different between CUP patients matching vs not matching the RESONATE criteria (Fig 4, p=0.29 for OS).In contrast to the first report (Winqvist et al., 2016), the negative impact on del17p was no longer significant but del17p patients who had 3 or more previous therapies had a short OS on ibrutinib (median 19.6 months). In univariate and multivariate analysis OS was associated with baseline comorbidities (CIRS) and PFS was associated with CIRS and number of prior therapies.Conclusions: The 21-month follow-up of the Swedish real-world analysis on ibrutinib treatment of CLL patients with poor prognosis baseline characteristics showed that 57% of patients remained on therapy, but there were still no signs of an emerging plateau of the PFS or OS curves. New RTs were still occurring. Ibrutinib was well tolerated by most patients. Updated results including a markedly longer follow-up will be presented at the meeting. [Display omitted] DisclosuresAndersson:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Speakers Bureau; GSK: Speakers Bureau. Karlsson:Janssen-Cilag: Honoraria; Abbvie: Honoraria. Lundin:Janssen-Cilag: Research Funding; Celgene: Research Funding. Mattsson:Janssen-Cilag: Honoraria; Gilead: Honoraria; Abbvie: Honoraria; Roche: Honoraria. Hansson:Gilead: Honoraria, Research Funding; Janssen-Cilag: Honoraria, Research Funding; Abbvie: Honoraria. Österborg:Pfizer: Honoraria; Abbvie: Honoraria; Celgene: Research Funding; Janssen-Cilag: Honoraria, Research Funding; Gilead: Honoraria, Research Funding.

Computational Integration to Model Tumor Dynamics in CLL Patients Treated with the Btk Inhibitor Ibrutinib (CompuTreatCLL): First Results of an Integrative Systems Biology Approach

Introduction: The Btk inhibitor ibrutinib is now a standard therapy for the treatment of CLL. Its daily and prolonged use results in a highly complex illness, the management of which poses multiple challenges. By impairing B-cell receptor signaling, survival, and homing of leukemic cells, ibrutinib purges CLL cells out of the lymphoid organs and/or induces their apoptosis. However, important inter-patient variability in the redistribution of the leukemic cells, the rate of leukemic cell elimination and the disparity of relapses call for an in-depth (i.e. systemic) analysis of the parameters influencing the dynamical behavior of the leukemic cell population in individual patients. In CompuTreatCLL project we consider treatment of CLL with ibrutinib as a prototypical showcase to implement an original systems biology approach in the management of this disease.Aims and methods: The overall objective of this project (started May 2016, 25 pts planned per year, 3 years of follow-up) is to elaborate a computational model that accounts for the physical and biological evolution of the CLL leukemic cell population during ibrutinib therapy. The collected data stem from pharmacokinetic study, dynamic imaging (whole-body diffusion-weighted MRI+Tepscan day 0-1-12-24 months), clinical evolution, and in vitro read-outs of leukemic cell viability, tumoral heterogeneity (by measuring relative apparent diffusion coefficients, or ADCs), and migrative/adhesion capacities of both tumoral B cells, nurselike cells and normal T cells (assessed with a high content screening imaging protocol).Results: The first month of ibrutinib therapy, we found three groups of response, as already described by A.wiestner's and J.Burger's groups. As expected, our first 24 patients segregate into 3 different subsets based on baseline fold-change of CD5+/CD19+ lymphocytes counts, monthly monitored from month 0-6 (n=8 each): group 1 had a transient (<2mo) lymphocytosis (median fold change <100) and then reduction, group 2 had reduction with no observable lymphocytosis, and group 3 had a prolonged hyperlymphocytosis (median fc 280, back to baseline >6mo). For the first time, we were able to correlate BTK/p-BTK levels, nodal/spleen bulk (in cubic centimeters), absolute numbers of normal immune subsets, PK parameters (Cmax, Cmin, AUC), and in vitro apoptotic response to 0.25microM ibrutinib measured at day 0 and day 30, to these 3 groups reflecting inter-patient variability.At baseline, response at 1 month was not predicted by BTK/pBTK levels, CD4/CD8/NK/B cells levels, but interestingly group 2 patients had significantly more Tregs cells and CD4/PD-1+ cells than in groups 1 and 3 (which had very similar immune subsets cell levels). In accordance publications about heavy water experiments and math models of kinetics of CLL cells in blood and tissues indicating that the reduction of disease burden is due more to cell death than egress from nodal compartments, we found that in vitro response to ibrutinib (before initiation of therapy in patients) was highly correlated to response group (mean % of B-cell depletion: 24% in group 3 vs 45% in group 2 vs 70% in group 2, correlation coefficient r2=0.4962, p<0.01). Interestingly, tissular disease as assessed with MRI was not different among the 3 groups.After one month, no PK parameter was correlated to response group. Median lymph node sizes reduction (evaluated with a in-house, informatic delineation tool to avoid long radiologist interpretation time) tends to be significantly higher in group 1 and 3 than in group 2.Conclusion: The project is expected to elucidate key questions about mechanisms underlying response to treatment, by identifying which biological parameters (from both CLL/normal T cells counterparts) are linked to the in vivo redistribution and to the clinical outcomes. At the time of data presentation in December, we will have more data for early 1 mo MRI, and 12 mo MRI to correlate clinical response with early parameters of response and the 3 groups of lymphocytosis behaviour. Ultimately, a mathematical model based on the most relevant parameters will be elaborated with the perspective in the future to benchmark tumor micro-environment-targeting agents, and also maybe link cellularity to sub-clonal evolution (as already reported with tyrosine kinase inhibitors in oncology). DisclosuresYsebaert:Janssen: Consultancy, Research Funding, Speakers Bureau. Recher:Celgene, Sunesis, Amgen, Novartis: Research Funding; Novartis, Celgene, Jazz, Sunesis, Amgen: Consultancy.

Ibrutinib Disrupts IL-4R - IL-4 Axis By Inhibiting IL-4R Signaling and Reversing Th2/Th1 Polarization through Diminished CLECL1 in CLL B Cells

The BTK inhibitor, ibrutinib, inhibits chronic lymphocytic leukemia (CLL) cell growth by blocking microenvironmental support in situ, releasing cells from tissues niches, and diminishing IL-4-producing T cells, all of which deprive leukemic cells of nurturing signals. However, little is known about the mechanisms whereby ibrutinib affects surface membrane (sm) levels of IL-4R and IL-4R signaling, Th2 polarization, particularly the relative sensitivities of U-CLL versus M-CLL to these effects of the drug, and how these parameters impact on those intraclonal CLL B cell fractions defined by time since last cell division. Hence we addressed these issues here.We studied 28 treatment-naive CLL patients receiving ibrutinib as single agent therapy. CLL B cells collected after ibrutinib treatment expressed lower densities of sm CD5, CD20, HLA-DR, CD25, and CD28; they also transiently displayed increased smIgM levels and persistently exhibited elevated but signaling-impeded smCXCR4. Moreover, ibrutinib treatment significantly lowered smIL-4R, without changing RNA or total protein content of the residual cells, suggesting that ibrutinib treatment may interrupt membrane trafficking. Finally, CLL B cells treated with ibrutinib exhibited significantly lower pSTAT6 and pJAK3 upon IL-4 stimulation, a here-to-fore unknown effect of BTK inhibition. Thus, ibrutinib impairs IL-4R sm expression and function.We next investigated if ibrutinib-impaired IL-4R signaling differentially affected the survival of U-CLL versus M-CLL cells. Supplementing leukemic B cell cultures with autologous T cells improved survival of U-CLL but not M-CLL cells. This T cell promoted survival was blocked by pretreatment of T cells with ibrutinib, or by co-culturing cells with IL-4 neutralizing antibody. Similarly, IL-4 improved the survival of U-CLL but not M-CLL cells in vitro, but only if the CLL B cells were tested before, but not after ibrutinib treatment in vivo . These findings were confirmed in a xenograft mouse model using primary treatment-naïve CLL patient cells; we observed greater inhibition of tissue-resident CLL B cell growth for U-CLL than M-CLL with ibrutinib therapy. Thus, IL-4R signaling is critical for CLL B cell survival, and U-CLL cells are more dependent on this than M-CLL.The CLL B cells remaining post-ibrutinib treatment were smaller, less viable and exhibited the resting phenotype described above; in almost all cases, ibrutinib eliminated the recently born, “proliferative fraction” (PF) of CLL cells, defined by a CXCR4DimCD5Bright phenotype. As suggested by our gene expression studies, we found that CLL PF cells display the highest levels of smIL-4R and smCLECL1, the latter is a receptor that induces Th2 polarization. Here we documented this by T cell polarization assays using autologous naïve CD4+ T cells co-cultured with CLL PF cells. However after ibrutinib treatment, PF cells taken from patients expressed lower smCLECL1 and failed to induce Th2 polarity. Thus, the Th1 polarization bias that occurs with ibrutinib treatment might result from direct targeting of ITK in T cells, as suggested by others, and by indirect targeting of CLECL1 on CLL cells as demonstrated here.Finally, PF cells from U-CLL patients have the highest levels of the anti-apoptotic protein BCL2. Ibrutinib treatment for 1 cycle significantly reduced BCL2 protein in U-CLL but not M-CLL cases. Notably, U-CLL cases with initial reduction of BCL2 that we followed to the end of cycle 3 treatment displayed increased BCL2 after cycles 2 and 3, suggesting that BTK inhibition initially selects clones expressing higher levels of BCL2. M-CLL cases however had invariant BCL2 protein during treatment, which might contribute to the better survival of M-CLL cells after the loss of environmental support.In summary, we report that ibrutinib interrupts the IL-4R - IL-4 axis by diminishing smIL-4R, smCLECL1, intracellular BCL2; and by promoting a non-IL-4 microenvironment thus favoring a Th1 cell bias. U-CLL B cells, in particular their PF, are more vulnerable to this action than M-CLL cells and therefore are more prone to die in tissue niches, consistent with M-CLL patients having greater and longer lymphocytosis when treated with ibrutinib. Thus our results provide a mechanistic understanding for the differences in primary ibrutinib sensitivity between U-CLL and M-CLL patients, supporting the rationale to combine inhibitors of BTK and BCL2 in CLL. DisclosuresBarrientos:AbbVie: Consultancy, Research Funding; Gilead: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Janssen: Consultancy. Burger:Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Novartis: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; Gilead: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; TG Therapeutics: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding.