Long-term outcomes for patients with chronic lymphocytic leukemia who discontinue ibrutinib

Richter's transformation: Transforming the clinical landscape

Richter transformation (RT) represents an aggressive histological transformation from chronic lymphocytic leukaemia, most often to a large B cell lymphoma. It is characterised by chemo-resistance and subsequent short survival. Drug development has struggled over recent years in light of the aggressive kinetics of the disease, lack of pivotal registrational trials and relative rarity of the phenomenon. In this review we will highlight the diagnostic and therapeutic challenges of managing patients with RT as well as taking a look to the future therapeutic landscape. Highly active therapies developed across B cell malignancies are starting to impact this field, with T-cell activation therapies (CAR-T, bispecific antibodies), antibody-drug conjugates, and novel small molecule inhibitor combinations (e.g. BTKi-BCL2i) being actively studied. We will highlight the data supporting these developments and look to the studies to come to provide hope for patients suffering from this devastating disease.

Oncogenic MTOR Signaling Axis Compensates BTK Inhibition in a Chronic Lymphocytic Leukemia Patient with Richter Transformation: A Case Report and Review of the Literature

INTRODUCTION

Targeting the B-cell receptor pathway via ibrutinib, a specific inhibitor of Bruton's tyrosine kinase, has shown marked clinical efficacy in treatment of patients with chronic lymphocytic leukemia (CLL), thus becoming a preferred first line option independent of risk factors. However, acquired resistance to ibrutinib poses a major clinical problem and requires the development of novel treatment combinations to increase efficacy and counteract resistance development and clinical relapse rates.

CASE PRESENTATION

In this study, we performed exome and transcriptome analyses of an ibrutinib resistant CLL patient in order to investigate genes and expression patterns associated with ibrutinib resistance. Here, we provide evidence that ibrutinib resistance can be attributed to aberrant mammalian target of rapamycin (MTOR) signaling.

CONCLUSION

Thus, our study proposes that combined use of MTOR inhibitors with ibrutinib could be a possible option to overcome therapy resistance in ibrutinib treated patients.

Ibrutinib discontinuation and associated factors in a real-world national sample of elderly Medicare beneficiaries with chronic lymphocytic leukemia

Prior studies evaluating ibrutinib discontinuation are limited to clinical trials and selected medical centers and hence may not reflect real-world practice. This study used Medicare claims (2013-2019) to examine ibrutinib discontinuation and associated factors among elderly patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Over a median follow-up of 2.1 years, two-thirds (65.2%) of the 11,870 new ibrutinib initiators were discontinued, with half (45.1%) of patients discontinuing within 12 months of initiation. Factors such as advanced age, lack of Part D low-income subsidy, evidence of prior CLL/SLL treatment, and cardiovascular comorbidities (e.g. atrial fibrillation) were associated with higher risk of discontinuation. Over a median of 1.2 years from discontinuation, 40% of discontinuers initiated another CLL/SLL treatment after ibrutinib discontinuation; 25% of patients restarted ibrutinib treatment at some point over follow-up. Our findings point to a large unmet need with the widely used BTKi ibrutinib and underscore the importance of ongoing development of efficacious and well-tolerated CLL/SLL therapies.

Results from a Real-World Multicenter Analysis of 482 Patients with Chronic Lymphocytic Leukemia Treated with Ibrutinib: A Look at Racial Differences

BACKGROUND

Despite recent approvals of lifesaving treatments for chronic lymphocytic leukemia (CLL), real-world data on the tolerability of the Bruton tyrosine kinase inhibitor ibrutinib for CLL treatment are lacking, especially in Black patients.

OBJECTIVE

To expand upon a previously reported retrospective chart review of ibrutinib-treated patients with CLL to increase the number of sites and the enrollment period in first-line (1L) and relapsed/refractory (R/R) settings with a subanalysis based on ethnicity.

PATIENTS AND METHODS

Adults with CLL who initiated ibrutinib treatment from five centers were followed for ≥ 6 months.

RESULTS

We identified 482 patients with CLL [405 White (153 1L, 252 R/R), 37 Black (17 1L, 20 R/R), 40 other/unidentified]. At baseline, 58.5% of all patients (68.8% of Black patients) had hypertension. At a median follow-up of 28.2 months, 31.1% of patients overall discontinued ibrutinib, 16.2% due to adverse events (12.2% 1L, 18.8% R/R). Overall, 46.0% of patients experienced ≥ 1 dose hold (40.2% 1L, 49.8% R/R), and 28.8% of patients experienced ≥ 1 dose reduction (24.9% 1L, 31.4% R/R). Among Black patients, ibrutinib was discontinued in 24.3% of patients (17.6% 1L, 30.0% R/R), 8.1% due to disease progression and 5.4% due to adverse events; 40.5% of patients experienced ≥ 1 dose hold (35.3% 1L, 45.0% R/R), and 32.4% of patients experienced ≥ 1 dose reduction (23.5% 1L, 40.0% R/R).

CONCLUSIONS

Toxicity and disease progression were the most common reasons for ibrutinib discontinuations in the overall population and among Black patients, respectively. Encouraging research participation of underrepresented patient groups will help clinicians better understand treatment outcomes.

Treatment Discontinuation Patterns for Patients With Chronic Lymphocytic Leukemia in Real-World Settings: Results From a Multi-Center International Study

INTRODUCTION

This study assessed treatment discontinuation patterns and reasons among chronic lymphocytic leukemia (CLL) patients initiating first-line (1L) and second-line (2L) treatments in real-world settings.

MATERIALS AND METHODS

Using deidentified electronic medical records from the CLL Collaborative Study of Real-World Evidence, premature treatment discontinuation was assessed among FCR, BR, BTKi-based, and BCL-2-based regimen cohorts.

RESULTS

Of 1364 1L patients (initiated in 1997-2021), 190/13.9% received FCR (23.7% discontinued prematurely); 255/18.7% received BR (34.5% discontinued prematurely); 473/34.7% received BTKi-based regimens, of whom 28.1% discontinued prematurely; and 43/3.2% received venetoclax-based regimens, of whom 16.3% discontinued prematurely (venetoclax monotherapy: 7/0.5%, of whom 42.9% discontinued; VG/VR: 36/2.6%, of whom 11.1% discontinued). The most common reasons for treatment discontinuation were adverse events (FCR: 25/13.2%; BR: 36/14.1%; BTKi-based regimens: 75/15.9%) and disease progression (venetoclax-based: 3/7.0%). Of 626 2L patients, 20/3.2% received FCR (50.0% discontinued); 62/9.9% received BR (35.5% discontinued); 303/48.4% received BTKi-based regimens, of whom 38.0% discontinued; and 73/11.7% received venetoclax-based regimens, of whom 30.1% discontinued (venetoclax monotherapy: 27/4.3%, of whom 29.6% discontinued; VG/VR: 43/6.9%, of whom 27.9% discontinued). The most common reasons for treatment discontinuation were adverse events (FCR: 6/30.0%; BR: 11/17.7%; BTKi-based regimens: 60/19.8%; venetoclax-based: 6/8.2%).

CONCLUSION

The findings of this study highlight the continued need for tolerable therapies in CLL, with finite therapy offering a better tolerated option for patients who are newly diagnosed or relapsed/refractory to prior treatments.

Approved Small-Molecule ATP-Competitive Kinases Drugs Containing Indole/Azaindole/Oxindole Scaffolds: R&D and Binding Patterns Profiling

Kinases are among the most important families of biomolecules and play an essential role in the regulation of cell proliferation, apoptosis, metabolism, and other critical physiological processes. The dysregulation and gene mutation of kinases are linked to the occurrence and development of various human diseases, especially cancer. As a result, a growing number of small-molecule drugs based on kinase targets are being successfully developed and approved for the treatment of many diseases. The indole/azaindole/oxindole moieties are important key pharmacophores of many bioactive compounds and are generally used as excellent scaffolds for drug discovery in medicinal chemistry. To date, 30 ATP-competitive kinase inhibitors bearing the indole/azaindole/oxindole scaffold have been approved for the treatment of diseases. Herein, we summarize their research and development (R&D) process and describe their binding models to the ATP-binding sites of the target kinases. Moreover, we discuss the significant role of the indole/azaindole/oxindole skeletons in the interaction of their parent drug and target kinases, providing new medicinal chemistry inspiration and ideas for the subsequent development and optimization of kinase inhibitors.

Characteristics and Clinical Outcomes of Patients with Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma Receiving Ibrutinib for ≥5 Years in the RESONATE-2 Study

Primary results from the phase 3 RESONATE-2 study demonstrated superior efficacy and tolerability with ibrutinib versus chlorambucil in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Here, we describe characteristics and outcomes of patients who received ibrutinib treatment for ≥5 years in RESONATE-2. Patients aged ≥65 years with previously untreated CLL/SLL, without del(17p), were randomly assigned 1:1 to once-daily ibrutinib 420 mg until disease progression/unacceptable toxicity (n = 136) or chlorambucil 0.5−0.8 mg/kg for ≤12 cycles (n = 133). Baseline characteristics in ibrutinib-randomized patients (n = 136) were generally similar between patients on ibrutinib treatment for ≥5 years (n = 79) versus those on treatment for <5 years (n = 57). In patients on ibrutinib treatment for ≥5 years, complete response rates improved over time, reaching 42% by 5 years. Estimated 7-year progression-free survival and overall survival rates were 82% and 94%, respectively. Adverse events (AEs) led to dose reductions in 16/79 patients (20%); these AEs were resolved for 13/16 patients (81%). AEs led to dose holds (≥7 days) in 45/79 patients (57%); these AEs were resolved for 43/45 patients (96%). More than half (58%) of ibrutinib-randomized patients benefitted from ibrutinib treatment for ≥5 years regardless of baseline characteristics. Dose modification resolved AEs for most patients, thereby facilitating continued treatment.

Evolutionary history of transformation from chronic lymphocytic leukemia to Richter syndrome

Richter syndrome (RS) arising from chronic lymphocytic leukemia (CLL) exemplifies an aggressive malignancy that develops from an indolent neoplasm. To decipher the genetics underlying this transformation, we computationally deconvoluted admixtures of CLL and RS cells from 52 patients with RS, evaluating paired CLL-RS whole-exome sequencing data. We discovered RS-specific somatic driver mutations (including IRF2BP2, SRSF1, B2M, DNMT3A and CCND3), recurrent copy-number alterations beyond del(9p21)(CDKN2A/B), whole-genome duplication and chromothripsis, which were confirmed in 45 independent RS cases and in an external set of RS whole genomes. Through unsupervised clustering, clonally related RS was largely distinct from diffuse large B cell lymphoma. We distinguished pathways that were dysregulated in RS versus CLL, and detected clonal evolution of transformation at single-cell resolution, identifying intermediate cell states. Our study defines distinct molecular subtypes of RS and highlights cell-free DNA analysis as a potential tool for early diagnosis and monitoring.

Clinical outcomes in patients with chronic lymphocytic leukemia with disease progression on ibrutinib

Patients with chronic lymphocytic leukemia (CLL) with disease progression on ibrutinib have worse outcomes compared to patients stopping ibrutinib due to toxicity. A better understanding of expected outcomes in these patients is necessary to establish a benchmark for evaluating novel agents currently available and in development. We evaluated outcomes of 144 patients with CLL treated at Mayo Clinic with 2018 iwCLL disease progression on ibrutinib. The median overall survival (OS) for the entire cohort was 25.5 months; it was 29.8 months and 8.3 months among patients with CLL progression (n = 104) and Richter transformation (n = 38), respectively. Longer OS was observed among patients with CLL progression who had received ibrutinib in the frontline compared to relapsed/refractory setting (not reached versus 28.5 months; p = 0.04), but was similar amongst patients treated with 1, 2, or ≥3 prior lines (18.5, 30.9, and 26.0 months, respectively, p = 0.24). Among patients with CLL disease progression on ibrutinib, OS was significantly longer when next-line treatment was chimeric antigen receptor T-cell therapy (median not reached) or venetoclax-based treatment (median 29.8 months) compared to other approved treatments, such as chemoimmunotherapy, phosphoinositide 3'-kinase inhibitors, and anti-CD20 monoclonal antibodies (9.1 months; p = 0.03). These findings suggest an unmet need for this growing patient population.

SOHO State of the Art Updates and Next Questions | Management of Most Difficult Cases of Chronic Lymphocytic Leukemia: Relapse After Both BTK and BCL2 Inhibition and Richter Transformation

The introduction of targeted therapies in chronic lymphocytic leukemia (CLL) has ushered in a new era in which patients achieve better control of their disease, survive longer, and experience fewer toxicities than before. Despite this progress, a subgroup of patients with CLL will develop resistance to both Bruton tyrosine kinase (BTK) and B-cell lymphoma 2 inhibitors. In addition, a subgroup of CLL cases will transform into aggressive lymphoma - called Richter transformation - either before or during targeted therapy. These two subgroups of patients have a poor prognosis, and available therapies lead to long-term remission in only a minority of patients. In this paper, two cases are presented that are reflective of these difficult scenarios. In the first case, a patient with CLL, complex karyotype, del 17p, and a mutation in TP53 experiences progression after ibrutinib, venetoclax, bendamustine, rituximab, and idelalisib. In the second case, a patient with CLL and del 17p develops a Richter transformation to diffuse large B-cell lymphoma after treatment with obinutuzumab, chlorambucil, ibrutinib, venetoclax, and idelalisib. The aggressive lymphoma is refractory to chemoimmunotherapy, and she expires. The literature pertaining to these two scenarios is reviewed, including the role of available targeted therapies, chemoimmunotherapy, and hematopoietic cell transplantation. Emerging novel therapies, including reversible BTK inhibitors and CAR T cell therapy, are discussed.

Cellular Therapy in High-Risk Relapsed/Refractory Chronic Lymphocytic Leukemia and Richter Syndrome

Despite the development of highly effective, targeted inhibitors of B-cell proliferation and anti-apoptotic pathways in chronic lymphocytic leukemia (CLL), these treatments are not curative, and many patients will develop either intolerance or resistance to these treatments. Transformation of CLL to high-grade lymphoma—the so-called Richter syndrome (RS)—remains a highly chemoimmunotherapy-resistant disease, with the transformation occurring following targeted inhibitors for CLL treatment being particularly adverse. In light of this, cellular therapy in the form of allogenic stem cell transplantation and chimeric antigen receptor T-cell therapy continues to be explored in these entities. We reviewed the current literature assessing these treatment modalities in both high-risk CLL and RS. We also discussed their current limitations and place in treatment algorithms.

Ibrutinib in the Treatment of Solid Tumors: Current State of Knowledge and Future Directions

Bruton's Tyrosine Kinase (BTK) is considered crucial in the activation and survival of both physiological and malignant B-cells. In recent years, ibrutinib, an oral BTK inhibitor, became a breakthrough therapy for hematological malignancies, such as chronic lymphocytic. However, ibrutinib's feasibility might not end there. Several other kinases with established involvement with solid malignancies (i.e., EGFR, HER2) have been found to be inhibited by this agent. Recent discoveries indicate that BTK is a potential anti-solid tumor therapy target. Consequently, ibrutinib, a BTK-inhibitor, has been studied as a therapeutic option in solid malignancies. While most preclinical studies indicate ibrutinib to be an effective therapeutic option in some specific indications, such as NSCLC and breast cancer, clinical trials contradict these observations. Nevertheless, while ibrutinib failed as a monotherapy, it might become an interesting part of a multidrug regime: not only has a synergism between ibrutinib and other compounds, such as trametinib or dactolisib, been observed in vitro, but this BTK inhibitor has also been established as a radio- and chemosensitizer. This review aims to describe the milestones in translating BTK inhibitors to solid tumors in order to understand the future potential of this agent better.

Biology and Treatment of Richter Transformation

Richter transformation (RT), defined as the development of an aggressive lymphoma on a background of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), represents a clinical unmet need because of its dismal prognosis. An increasing body of knowledge in the field of RT is arising from the recent development of preclinical models depicting the biology underlying this aggressive disease. Consistently, new therapeutic strategies based on a genetic rationale are exploring actionable pathogenic pathways to improve the outcome of patients in this setting. In this review, we summarize the current understandings on RT biology and the available treatment options.

Clinical outcome of allogeneic stem cell transplantation in patients with B-cell lymphoid malignancies following treatment with targeted small molecule inhibitors

We aimed to study the risks of graft-versus-host disease (GVHD), non-relapse mortality (NRM) and survival outcomes of allogeneic stem cell transplantation (alloSCT) in patients with chronic lymphocytic leukemia (n = 17), Richter's syndrome (n = 14), or lymphoma (n = 18) after small molecule inhibitors (SMIs). Patients had a median of 4 prior therapies, including ibrutinib (n = 46; 94%), venetoclax (n = 19; 39%), and idelalisib (n = 6; 12%). Twenty-one (43%) had >1 SMI. P53 mutation was detected in 58% of patients. The 3-year overall and progression-free survival rates were 68% and 59%, respectively. The rates of grade II-IV and III-IV acute GVHD were 33% and 7%. The 1-year rates of chronic GVHD, NRM and relapse were 19%, 10% and 21%, respectively. Results were comparable to a historical control of patients who received alloSCT without a prior exposure to SMI. We conclude that a prior use of SMI does not impair the outcomes after alloSCT.

Antiviral and anti-inflammatory drugs to combat COVID-19: Effects on cardiac ion channels and risk of ventricular arrhythmias

Introduction: Drugs with no indication for the treatment of cardiovascular diseases (e.g., drugs employed to treat COVID-19) can increase the risk of arrhythmias. Of interest, a six-fold increase in the number of arrhythmic events was reported in patients with severe COVID-19. In this study, we reviewed (i) the pro-arrhythmic action of drugs given to patients with COVID-19 infection, and (ii) the effects of inflammatory cytokines on cardiac ion channels and possible generation of arrhythmias.

Methods: We conducted a literature search on the drugs with purported or demonstrated efficacy against COVID-19 disease, emphasizing the mechanisms by which anti-COVID-19 drugs and inflammatory cytokines interfere with cardiac ion channels.

Results:Antibiotics (azithromycin), antimalarials (hydroxychloroquine, chloroquine), antivirals (ritonavir/lopinavir, atazanavir), and some of the tyrosine kinase inhibitors (vandetanib) could induce long QT and increase risk for ventricular arrhythmias. The pro-arrhythmic action results from drug-induced inhibition of Kv11.1 (hERG) channels interfering with the repolarizing potassium IKr currents, leading to long QT and increased risk of triggered arrhythmias. At higher concentrations, these drugs may interfere with IKs, IK1, and/or Ito potassium currents, and even inhibit sodium (INa) and calcium (ICa) currents, inducing additional cardiac toxicity. Ibrutinib, an inhibitor of Bruton’s TK, increased the incidence of atrial fibrillation and ventricular tachycardia associated with a short QT interval. Inflammatory cytokines IL-6 and TNF-α inhibit IKr and Ito repolarizing potassium currents. High levels of inflammatory cytokines could contribute to the arrhythmic events. For remdesivir, favipiravir, dexamethasone, tocilizumab, anakinra, baricitinib, and monoclonal antibodies (bamlanivimab, etesevimab, and casirivimab), no evidence supports significant effects on cardiac ion channels, changes in the QT interval, and increased risk for ventricular arrhythmias.

Conclusion: This study supports the concept of hERG channel promiscuity. Different drug classes given to COVID-19 patients might delay repolarization, and increase the risk of ventricular arrhythmias. The presence of comorbid pro-arrhythmic disease states, and elevated levels of pro-arrhythmic cytokines, could increase the risk of ventricular arrhythmias. Discontinuation of nonessential drugs and correction of electrolyte abnormalities could prevent severe ventricular arrhythmias. Altogether, the most effective therapies against COVID-19 (remdesivir, dexamethasone, monoclonal antibodies) lack pro-arrhythmic activity.

Efficacy of Front-Line Ibrutinib and Rituximab Combination and the Impact of Treatment Discontinuation in Unfit Patients with Chronic Lymphocytic Leukemia: Results of the Gimema LLC1114 Study

Simple Summary

This prospective, multicenter study aimed to investigate the efficacy and safety of a front-line treatment with the ibrutinib and rituximab combination in 146 unfit patients with chronic lymphocytic leukemia (CLL). We observed an OR, CR, and 48-month PFS rates of 87%, 22.6%, and 77%, respectively. Responses with undetectable MRD were observed in 6.2% of all patients and 27% of CR patients. TP53 disruption and B-symptoms revealed a significant and independent impact on PFS. The 48-month cumulative treatment discontinuation rate due to adverse events in this patient population was 29.1%. It was significantly higher in male patients, in patients aged ≥70 years, and in those managed at centers that enrolled less than five patients. In conclusion, the ibrutinib and rituximab combination was an effective front-line treatment for unfit patients with CLL. However, a high rate of treatment discontinuations due to adverse events was observed in this unfit population.

Abstract

The GIMEMA group investigated the efficacy, safety, and rates of discontinuations of the ibrutinib and rituximab regimen in previously untreated and unfit patients with chronic lymphocytic leukemia (CLL). Treatment consisted of ibrutinib, 420 mg daily, and until disease progression, and rituximab (375 mg/sqm, given weekly on week 1–4 of month 1 and day 1 of months 2–6). This study included 146 patients with a median age of 73 years, with IGHV unmutated in 56.9% and TP53 disrupted in 22.2%. The OR, CR, and 48-month PFS rates were 87%, 22.6%, and 77%, respectively. Responses with undetectable MRD were observed in 6.2% of all patients and 27% of CR patients. TP53 disruption (HR 2.47; p = 0.03) and B-symptoms (HR 2.91; p = 0.02) showed a significant and independent impact on PFS. The 48-month cumulative rates of treatment discontinuations due to disease progression (DP) or adverse events (AEs) were 5.6% and 29.1%, respectively. AEs leading more frequently to treatment discontinuation were atrial fibrillation in 8% of patients, infections in 8%, and non-skin cancers in 6%. Discontinuation rates due to AEs were higher in male patients (HR: 0.46; p = 0.05), patients aged ≥70 years (HR 5.43, p = 0.0017), and were managed at centers that enrolled <5 patients (HR 5.1, p = 0.04). Patients who discontinued ibrutinib due to an AE showed a 24-month next treatment-free survival rate of 63%. In conclusion, ibrutinib and rituximab combination was an effective front-line treatment with sustained disease control in more than half of unfit patients with CLL. Careful monitoring is recommended to prevent and manage AEs in this patient population.

Implementation of a clinical decision rule for selecting empiric treatment for invasive aspergillosis in a setting with high triazole resistance

World-wide, emerging triazole resistance increasingly complicates treatment of invasive aspergillosis (IA). In settings with substantial (>10%) prevalence of triazole resistance, empiric combination therapy with both a triazole and liposomal amphotericin B (LAmB) can be considered because of the low yields of susceptibility testing. To avoid toxicity while optimizing outcome, a strategy with monotherapy would be preferable. A newly designed treatment algorithm based on literature and expert consensus provided guidance for empiric monotherapy with either voriconazole or LAmB. Over a four and a half year period, all adult patients in our hospital treated for IA were included and patient data were collected. An independent committee reviewed the attributability of death to IA for each patient. Primary outcomes were 30- and 100-day crude mortality and attributable mortality. In total, 110 patients were treated according to the treatment algorithm. Fifty-six patients (51%) were initially treated with voriconazole and 54 patients (49%) with LAmB. Combined attributable and contributable mortality was 13% within 30 days and 20% within 100 days. Treatment switch to LAmB was made in 24/56 (43%) of patients who were initially treated with voriconazole. Combined contributable and attributable 100-day mortality in this subgroup was 21% and was not increased when compared with patients initially treated with LAmB (P = 0.38). By applying a comprehensive clinical decision algorithm, an antifungal-sparing regime was successfully introduced. Further research is warranted to explore antifungal treatment strategies that account for triazole-resistance.

LAY SUMMARY

Due to resistance of Aspergillus against triazoles, combination therapy with liposomal amphotericin B (LAmB) is applied more often as primary therapy against invasive aspergillosis. This study presents the results of a decision tool which differentiated between triazole or LAmB monotherapy.

Clinical utility of chromosomal microarray in establishing clonality and high risk features in patients with Richter transformation

Richter transformation (RT) refers to the development of an aggressive lymphoma in patients with pre-existing chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). It carries a poor prognosis secondary to poor response to therapy or rapid disease relapse. Currently there are no randomized trials to guide treatment. Therapeutic decisions are often influenced by the presence or absence of a clonal relationship between the underlying CLL/SLL and the new lymphoma given the poor prognosis of patients with clonally related RT. Chromosomal microarray analysis (CMA) can help to establish clonality while also detecting genomic complexity and clinically relevant genetic variants such as loss of CDKN2A and/or TP53. As a result, CMA has potential prognostic and therapeutic implications. For this study, CMA results from patients with Richter transformation were evaluated in paired CLL/SLL and transformed lymphoma samples. CMA revealed that 86% of patients had common aberrations in the two samples indicating evidence of common clonality. CMA was also useful in detecting aberrations associated with a poor prognosis in 71% of patients with RT. This study highlights the potential clinical utility of CMA to investigate the clonal relationship between CLL/SLL and RT, provide prognostic information, and possibly guide therapeutic decision making for patients with Richter transformation.

Review of the development of BTK inhibitors in overcoming the clinical limitations of ibrutinib

Bruton's tyrosine kinase (BTK) regulates multiple important signaling pathways and plays a key role in the proliferation, survival, and differentiation of B-lineage cells and myeloid cells. BTK is a promising target for the treatment of hematologic malignancies. Ibrutinib, the first-generation BTK inhibitor, was approved to treat several B-cell malignancies. Despite the remarkable potency and efficacy of ibrutinib against various lymphomas and leukemias in the clinics, there are also some clinical limitations, such as off-target toxicities and primary/acquired drug resistance. As strategies to overcome these challenges, second- and third-generation BTK inhibitors, BTK-PROTACs, as well as combination therapies have been explored. In this review, we summarize clinical developments of the first-, second- and third-generation BTK inhibitors, as well as recent advances in BTK-PROTACs and ibrutinib-based combination therapies.

Pre-existing cardiovascular disease increases risk of atrial arrhythmia and mortality in cancer patients treated with Ibrutinib

Background

Ibrutinib is a Bruton’s tyrosine kinase inhibitor used in the treatment of hematological malignancies. The most common cardiotoxicity associated with ibrutinib is atrial arrhythmia (atrial fibrillation and flutter). It is known that patients with cardiovascular disease (CVD) are at an increased risk for developing atrial arrhythmia. However, the rate of atrial arrhythmia in patients with pre-existing CVD treated with ibrutinib is unknown.

Objective

This study examined whether patients with pre-existing CVD are at a higher risk for developing atrial arrhythmias compared to those without prior CVD.

Methods

A single-institution retrospective chart review of patients with no prior history of atrial arrhythmia treated with ibrutinib from 2012 to 2020 was performed. Patients were grouped into two cohorts: those with CVD (known history of coronary artery disease, heart failure, pulmonary hypertension, at least moderate valvular heart disease, or device implantation) and those without CVD. The primary outcome was incidence of atrial arrhythmia, and the secondary outcomes were all-cause mortality, risk of bleeding, and discontinuation of ibrutinib. The predictors of atrial arrhythmia (namely atrial fibrillation) were assessed using logistic regression. A Cox-Proportional Hazard model was created for mortality.

Results

Patients were followed for a median of 1.1 years. Among 217 patients treated with ibrutinib, the rate of new-onset atrial arrhythmia was nearly threefold higher in the cohort with CVD compared to the cohort without CVD (17% vs 7%, p = 0.02). Patients with CVD also demonstrated increased adjusted all-cause mortality (OR 1.9, 95% CI 1.06-3.41, p = 0.01) and decreased survival probability (43% vs 54%, p = 0.04) compared to those without CVD over the follow-up period. There were no differences in risk of bleeding or discontinuation between the two cohorts.

Conclusions

Pre-existing cardiovascular disease was associated with significantly higher rates of atrial arrhythmia and mortality in patients with hematological malignancies managed with ibrutinib.

Targeting of HSP70/HSF1 Axis Abrogates In Vitro Ibrutinib-Resistance in Chronic Lymphocytic Leukemia

Simple Summary

The use of ibrutinib has changed the management and clinical history of patients with multiple-treated chronic lymphocytic leukemia (CLL). Nevertheless, an increasing number of patients develop resistance to treatment, with mechanisms still to be fully clarified. Since HSP70 plays a pivotal role in mediating the survival and the progression of CLL, we herein addressed the role of HSP70 and its regulator HSF1 in the development of ibrutinib-mediated resistance. We found an increase in both proteins when the treatment was failing, and thus the disease was progressing. This suggests the involvement of HSP70 in mechanisms of drug resistance. Moreover, we demonstrated that the use, at different levels, of HSP70/HSF1 axis inhibitors could represent a novel rational therapeutic approach to overcome ibrutinib resistance in those patients who relapsed after this type of treatment.

Abstract

The Btk inhibitor ibrutinib has significantly changed the management of chronic lymphocytic leukemia (CLL) patients. Despite its clinical efficacy, relapses occur, and outcomes after ibrutinib failure are poor. Although BTK and PLCγ2 mutations have been found to be associated with ibrutinib resistance in a fair percentage of CLL patients, no information on resistance mechanisms is available in patients lacking these mutations. The heat shock protein of 70 kDa (HSP70) and its transcription factor heat shock factor 1 (HSF1) play a role in mediating the survival and progression of CLL, as well as taking part in drug resistance in various cancers. We demonstrated that resveratrol and related phenols were able to induce apoptosis in vitro in leukemic cells from CLL untreated patients by acting on the HSP70/HSF1 axis. The same was achieved in cells recovered from 13 CLL patients failing in vivo ibrutinib treatment. HSP70 and HSF1 levels decreased following in vitro treatment, correlating to apoptosis induction. We suggest an involvement of HSP70/HSF1 axis in controlling resistance to ibrutinib in CLL cells, since their inhibition is effective in inducing in vitro apoptosis in cells from ibrutinib refractory patients. The targeting of HSP70/HSF1 axis could represent a novel rational therapeutic strategy for CLL, also for relapsing patients.

Autologous and allogeneic hematopoietic cell transplantation for diffuse large B-cell lymphoma-type Richter syndrome

Richter syndrome (RS) represents a transformation from chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) to aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL), which is associated with a dismal prognosis. Patients with DLBCL-RS have poor outcomes with DLBCL-directed therapy; thus, consolidation with hematopoietic cell transplantation (HCT) has been used, with durable remissions observed. Studies reporting HCT outcomes in patients with DLBCL-RS have been small, have not evaluated the prognostic impact of cytogenetic risk factors, and were conducted prior to the era of novel targeted therapy of CLL/SLL. We performed a Center for International Blood and Transplant Research registry study evaluating outcomes after autologous HCT (auto-HCT; n = 53) and allogeneic HCT (allo-HCT; n = 118) in patients with DLBCL-RS treated in the modern era. More auto-HCT recipients were in complete response (CR) at HCT relative to allo-HCT recipients (66% vs 34%), whereas a higher proportion of allo-HCT recipients had 17p deletion (33% vs 7%) and had previously received novel agents (39% vs 10%). In the auto-HCT cohort, the 3-year relapse incidence, progression-free survival (PFS), and overall survival (OS) were 37%, 48%, and 57%, respectively. Among allo-HCT recipients, the 3-year relapse incidence, PFS, and OS were 30%, 43%, and 52%, respectively. In the allo-HCT cohort, deeper response at HCT was associated with outcomes (3-year PFS/OS, 66%/77% CR vs 43%/57% partial response vs 5%/15% resistant; P < .0001 for both), whereas cytogenetic abnormalities and prior novel therapy did not impact outcomes. In our study, HCT resulted in durable remissions in therapy-sensitive patients with DLBCL-RS treated in the era of targeted CLL/SLL therapy, including patients with high-risk features.

Morphologic and molecular analysis of Richter syndrome in chronic lymphocytic leukaemia patients treated with ibrutinib or venetoclax

Richter syndrome (RS) represents the development of high-grade lymphoma in patients with chronic lymphocytic leukaemia (CLL) or small lymphocytic lymphoma (SLL) and presents a diagnostic and therapeutic challenge with an adverse prognosis. The genetic background and morphology of RS in CLL patients treated with chemoimmunotherapy is extensively characterised; however, our knowledge about RS in patients treated with targeted oral therapies should be extended. To understand the morphologic and molecular changes leading to RS in CLL patients treated with the Bruton's tyrosine kinase inhibitor, ibrutinib, and the BCL2 inhibitor, venetoclax, sequential samples from six CLL/SLL patients undergoing RS were collected in both the CLL and RS phases. A detailed immunophenotypic analysis of formalin-fixed, paraffin-embedded tissue specimens of RS phase was performed, followed by extensive molecular characterisation of CLL and RS samples, including the immunoglobulin heavy chain gene (IGH) rearrangement, TP53 mutations, drug-induced resistance mutations in BTK and BCL2 genes and various copy number changes and point mutations detectable with multiplex ligation-dependent probe amplification (MLPA). Rare, non-diffuse large B-cell lymphoma phenotypes of RS were observed in 3/6 cases, including plasmablastic lymphoma and a transitory entity between diffuse large B-cell lymphoma and classical Hodgkin lymphoma. The majority of cases were clonally related and harboured an unmutated variable region of the immunoglobulin heavy chain gene. Abnormalities affecting the TP53 gene occurred in all patients, and every patient carried at least one genetic abnormality conferring susceptibility to RS. In the background of RS, 2/5 patients treated with ibrutinib showed a BTK C481S resistance mutation. One patient developed a BCL2 G101V mutation leading to venetoclax resistance and RS. In conclusion, our findings contribute to better understanding of RS pathogenesis in the era of targeted oral therapies. Rare phenotypic variants of RS do occur under the treatment of ibrutinib or venetoclax, and genetic factors leading to RS are similar to those identified in patients treated with chemoimmunotherapy. To our best knowledge, we have reported the first BCL2 G101V mutation in an RS patient treated with venetoclax.

Outcomes of Richter's transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL): an analysis of the SEER database

Richter's transformation (RT) is a rare complication arising in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and is associated with an overall dismal outcome. The rarity of this entity poses many challenges in understanding its biology and outcomes seen and the optimal treatment approach. We utilized the SEER (Surveillance, Epidemiology and End Results) database to identify patients diagnosed with CLL/SLL between 2000 and 2016 and subsequently had a diagnosis of diffuse large B-cell lymphoma (DLBCL) or Hodgkin lymphoma (HL), thus capturing those who experienced an RT event. We compared the outcomes of those patients to those of patients in the database diagnosed with DLBCL without a preceding CLL/SLL diagnosis. We identified 530 patients who developed RT out of 74,116 patients diagnosed with CLL/SLL in the specified period. The median age at RT diagnosis was 66 years, and the median time from CLL/SLL diagnosis to RT development was roughly 4 years. Patients with RT had a dismal outcome with median overall survival of 10 months. We identified advanced Ann Arbor stage (III/IV) and prior treatment for CLL as predictors of worse outcome in patients with RT. Our study represents the largest dataset of patients with CLL/SLL and RT and adds to the existing literature indicating the poor outcomes for those patients.

Efficacy of minimal residual disease driven immune-intervention after allogeneic hematopoietic stem cell transplantation for high-risk chronic lymphocytic leukemia: results of a prospective multicenter trial

Allogeneic hematopoietic stem cell transplantation (HSCT) remains a potentially curative and useful strategy in high-risk relapsing chronic lymphocytic leukemia (CLL). Minimal residual disease (MRD) assessment at 12 months (M12) post-HSCT is predictive of relapse. This phase II study aimed to achieve M12 MRD negativity (MRDneg) using an MRD-driven immune-intervention (Md-PII) algorithm based on serial flow-cytometry blood MRD, involving cyclosporine tapering followed in case of failure by donor lymphocytes infusions. Patients had high-risk CLL according to the 2006 European Society for Blood and Marrow Transplantation consensus, in complete or partial response with lymphadenopathy <5 cm and comorbidity score ≤2. Donors were HLA-matched sibling or matched unrelated (10/10). Fortytwo enrolled patients with either 17p deletion (front-line, n=11; relapse n=16) or other high-risk relapse (n=15) received reduced intensity-conditioning regimen before HSCT and were submitted to Md-PII. M12- MRDneg status was achieved in 27 of 42 patients (64%) versus 6 of 42 (14.2%) before HSCT. With a median follow-up of 36 months (range, 19-53), 3-year overall survival, non-relapse mortality and cumulative incidence of relapse are 86.9% (95% Confidence Interval [CI]: 70.8-94.4), 9.5% (95% CI: 3.7-23.4) and 29.6% (95% CI: 17.3-47.7). Incidence of 2-year limited and extensive chronic graft versus host disease (cGVHD) is 38% (95% CI: 23-53) and 23% (95% CI: 10-36) including two cases post Md-PII. Fifteen patients converted to MRDneg either after cyclosporine A withdrawal (n=12) or after cGvHD (n=3). As a time-dependent variable, MRDneg achievement at any time-point correlates with reduced relapse (Hazard ratio [HR] 0.14 [range, 0.04-0.53], P=0.004) and improvement of both progression free (HR 0.18 [range, 0.06-0.6], P<0.005) and overall (HR 0.18 [range, 0.03-0.98], P=0.047) survival. These data highlight the value of MRD-driven immune-intervention to induce prompt MRD clearance in the therapy of CLL (clinicaltrials gov. Identifier: NCT01849939).

Durable Remissions Following Combined Targeted Therapy in Patients with CLL Harboring TP53 Deletions and/or Mutations

Fifty-one of 189 evaluable patients from three prospective phase-II trials evaluating a sequential targeted treatment (clinicaltrials.gov NCT02345863, NCT02401503, NCT02689141) had high-risk CLL with a deletion 17p, TP53 mutation or both. Twenty-seven patients started treatment with bendamustine debulking prior to the induction and maintenance treatment, which was ibrutinib/ofatumumab (IO) in 21 patients, ibrutinib/obinutuzumab (IG) in 13 and venetoclax/obinutuzumab (AG) in 17 patients. The primary endpoint was the overall response rate after eight months of induction treatment, which were 81%, 100% and 94% for IO, IG and AG, respectively. Minimal residual disease (MRD) was undetectable in peripheral blood (uMRD; <10-4 by flow cytometry) in 0%, 23% and 82% of patients, respectively. Median progression free survival (PFS) was 45 months. Seventeen patients discontinued maintenance treatment due to undetectable MRD, nine of them progressed and two died without progression (median PFS: 28 months after discontinuation of treatment), while six patients remained in remission after a median observation time of 46 (range 6-47) months after discontinuation of treatment. Thus, MRD-guided fix-duration therapies combining obinutuzumab with venetoclax or ibrutinib can induce deep and durable remissions in CLL patients with high-risk genetic lesions, which can persist after treatment discontinuation.

The Ongoing Unmet Needs in Chronic Lymphocytic Leukemia: TP53 Disruption, Richter, and Beyond

Despite recent success in regard to targeted therapies in chronic lymphocytic leukemia (CLL), patients with TP53 disruption (including deletion and/or mutation) continue to have poor outcomes compared with other patients with CLL. In this article, a review of common TP53 mutations in CLL, and recent trials using novel targeted agents in CLL patients with TP53 disruption, is provided with the goal of emphasizing the need to continuously focus on this area of research. In addition, limited but available data on double refractory CLL to BTK inhibitor and BCL-2 inhibitor, and on Richter syndrome, are reviewed.

Treatment of Chronic Lymphocytic Leukemia After Discontinuation of Bruton's Tyrosine Kinase Inhibitors

The Bruton's tyrosine kinase inhibitors (BTKis) ibrutinib and acalabrutinib have led to durable responses for patients with both treatment-naïve and relapsed/refractory chronic lymphocytic leukemia (CLL). Many patients, however, ultimately discontinue BTKis due to toxicity or progressive CLL. This article reviews the two most common reasons for ibrutinib and acalabrutinib discontinuation, including adverse events as well as CLL progression. The data for specific CLL-directed therapies following BTKi discontinuation, including venetoclax, phosphatidylinositol 3-kinase inhibitors, cellular therapies, and ongoing clinical trials, are reviewed. An evidence-based sequencing algorithm for treatment of CLL following BTKi discontinuation is proposed.

Phase 2 study of the safety and efficacy of umbralisib in patients with CLL who are intolerant to BTK or PI3Kδ inhibitor therapy

Intolerance is the most common reason for kinase inhibitor (KI) discontinuation in chronic lymphocytic leukemia (CLL). Umbralisib, a novel highly selective phosphatidylinositol 3-kinase δ (PI3Kδ)/CK1ε inhibitor, is active and well tolerated in CLL patients. In this phase 2 trial (NCT02742090), umbralisib was initiated at 800 mg/d in CLL patients requiring therapy, who were intolerant to prior BTK inhibitor (BTKi) or PI3K inhibitor (PI3Ki) therapy, until progression or toxicity. Primary end point was progression-free survival (PFS). Secondary end points included time to treatment failure and safety. DNA was genotyped for CYP3A4, CYP3A5, and CYP2D6 polymorphisms. Fifty-one patients were enrolled (44 BTKi intolerant and 7 PI3Kδi intolerant); median age was 70 years (range, 48-96), with a median of 2 prior lines of therapy (range, 1-7), 24% had del17p and/or TP53 mutation, and 65% had unmutated IGHV. Most common adverse events (AEs) leading to prior KI discontinuation were rash (27%), arthralgia (18%), and atrial fibrillation (16%). Median PFS was 23.5 months (95% CI, 13.1-not estimable), with 58% of patients on umbralisib for a longer duration than prior KI. Most common (≥5%) grade ≥3 AEs on umbralisib (all causality) were neutropenia (18%), leukocytosis (14%), thrombocytopenia (12%), pneumonia (12%), and diarrhea (8%). Six patients (12%) discontinued umbralisib because of an AE. Eight patients (16%) had dose reductions and were successfully rechallenged. These are the first prospective data to confirm that switching from a BTKi or alternate PI3Ki to umbralisib in this BTKi- and PI3Ki-intolerant CLL population can result in durable well-tolerated responses.

Genomic and transcriptomic correlates of Richter transformation in chronic lymphocytic leukemia

The transformation of chronic lymphocytic leukemia (CLL) to high-grade B-cell lymphoma is known as Richter syndrome (RS), a rare event with dismal prognosis. In this study, we conducted whole-genome sequencing (WGS) of paired circulating CLL (PB-CLL) and RS biopsies (tissue-RS) from 17 patients recruited into a clinical trial (CHOP-O). We found that tissue-RS was enriched for mutations in poor-risk CLL drivers and genes in the DNA damage response (DDR) pathway. In addition, we identified genomic aberrations not previously implicated in RS, including the protein tyrosine phosphatase receptor (PTPRD) and tumor necrosis factor receptor-associated factor 3 (TRAF3). In the noncoding genome, we discovered activation-induced cytidine deaminase-related and unrelated kataegis in tissue-RS affecting regulatory regions of key immune-regulatory genes. These include BTG2, CXCR4, NFATC1, PAX5, NOTCH-1, SLC44A5, FCRL3, SELL, TNIP2, and TRIM13. Furthermore, differences between the global mutation signatures of pairs of PB-CLL and tissue-RS samples implicate DDR as the dominant mechanism driving transformation. Pathway-based clonal deconvolution analysis showed that genes in the MAPK and DDR pathways demonstrate high clonal-expansion probability. Direct comparison of nodal-CLL and tissue-RS pairs from an independent cohort confirmed differential expression of the same pathways by RNA expression profiling. Our integrated analysis of WGS and RNA expression data significantly extends previous targeted approaches, which were limited by the lack of germline samples, and it facilitates the identification of novel genomic correlates implicated in RS transformation, which could be targeted therapeutically. Our results inform the future selection of investigative agents for a UK clinical platform study. This trial was registered at www.clinicaltrials.gov as #NCT03899337.

Incidental Richter transformation in chronic lymphocytic leukemia patients during temporary interruption of ibrutinib

An incidental histologic diagnosis of DLBCL was identified during temporary interruption of ibrutinib treatment in patients with CLL. In contrast to an aggressive clinical course typical of Richter transformation, these patients responded to reinitiation of ibrutinib alone.

Real-world treatment patterns, adverse events and clinical outcomes in patients with chronic lymphocytic leukaemia treated with ibrutinib in the UK

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in adults in the UK. Ibrutinib, an oral Bruton tyrosine kinase inhibitor (BTKi) for CLL approved by the UK's National Institute for Health and Care Excellence in January 2017, represented a major shift in CLL management. Real-world data on ibrutinib use in routine clinical practice will inform patients' and physicians' decision-making. We conducted a retrospective medical chart review of UK patients with CLL who initiated ibrutinib between January 2017 and July 2018. Data for 259 patients were contributed by 34 haematology-oncology specialists, with a median follow-up duration of 16.7 months. Median age at ibrutinib initiation was 71 years. Ibrutinib first-line monotherapy was prescribed in 20.1% of patients. Ibrutinib was permanently discontinued in 15.4% of patients, mostly owing to progressive disease. Adverse events (AEs) were reported in 151 patients (58.3%). The most common were bruising (19.3% of patients), cytopenias (17.0%) and diarrhoea (11.6%). Ibrutinib dose reduction was observed in 14.3% of patients and was temporarily discontinued in 10.4% of patients, with the main reason for both being toxicity. These results expand the real-world evidence on ibrutinib therapy and demonstrate a high burden of AEs, highlighting the need for more tolerable BTKis.

Cost-effectiveness of first-line vs third-line ibrutinib in patients with untreated chronic lymphocytic leukemia

The ALLIANCE A041202 trial found that continuously administered ibrutinib in the first-line setting significantly prolonged progression-free survival compared with a fixed-duration treatment of rituximab and bendamustine in older adults with chronic lymphocytic leukemia (CLL). In this study, we created a Markov model to assess the cost-effectiveness of ibrutinib in the first-line setting, compared with a strategy of using ibrutinib in the third-line after failure of time-limited bendamustine and venetoclax-based regimens. We estimated transition probabilities from randomized trials using parametric survival modeling. Lifetime direct health care costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios (ICERs) were calculated from a US payer perspective. First-line ibrutinib was associated with an improvement of 0.26 QALYs and 0.40 life-years compared with using ibrutinib in the third-line setting. However, using ibrutinib in the first-line led to significantly higher health care costs (incremental cost of $612 700), resulting in an ICER of $2 350 041 per QALY. The monthly cost of ibrutinib would need to be decreased by 72% for first-line ibrutinib therapy to be cost-effective at a willingness-to-pay threshold of $150 000 per QALY. In a scenario analysis where ibrutinib was used in the second-line in the delayed ibrutinib arm, first-line ibrutinib had an incremental cost of $478 823, an incremental effectiveness of 0.05 QALYs, and an ICER of $9 810 360 per QALY when compared with second-line use. These data suggest that first-line ibrutinib for unselected older adults with CLL is unlikely to be cost-effective under current pricing. Delaying ibrutinib for most patients with CLL until later lines of therapy may be a reasonable strategy to limit health care costs without compromising clinical outcomes.

Interleukin-10 suppression enhances T-cell antitumor immunity and responses to checkpoint blockade in chronic lymphocytic leukemia

T-cell dysfunction is a hallmark of B-cell Chronic Lymphocytic Leukemia (CLL), where CLL cells downregulate T-cell responses through regulatory molecules including programmed death ligand-1 (PD-L1) and Interleukin-10 (IL-10). Immune checkpoint blockade (ICB) aims to restore T-cell function by preventing the ligation of inhibitory receptors like PD-1. However, most CLL patients do not respond well to this therapy. Thus, we investigated whether IL-10 suppression could enhance antitumor T-cell activity and responses to ICB. Since CLL IL-10 expression depends on Sp1, we utilized a novel, better tolerated analogue of the Sp1 inhibitor mithramycin (MTM_ox32E) to suppress CLL IL-10. MTM_ox32E treatment inhibited mouse and human CLL IL-10 production and maintained T-cell effector function in vitro. In the Eμ-Tcl1 mouse model, treatment reduced plasma IL-10 and CLL burden and increased CD8⁺ T-cell proliferation, effector and memory cell prevalence, and interferon-γ production. When combined with ICB, suppression of IL-10 improved responses to anti-PD-L1 as shown by a 4.5-fold decrease in CLL cell burden compared to anti-PD-L1 alone. Combination therapy also produced more interferon-γ⁺, cytotoxic effector KLRG1⁺, and memory CD8⁺ T-cells, and fewer exhausted T-cells. Since current therapies for CLL do not target IL-10, this provides a novel strategy to improve immunotherapies.

Revisiting Richter transformation in the era of novel CLL agents

Richter transformation (RT) is the development of aggressive lymphoma - most frequently diffuse large B-cell lymphoma (DLBCL) and rarely Hodgkin lymphoma (HL) - arising on the background of chronic lymphocytic leukaemia (CLL). Despite recent advances in CLL treatment, RT also develops in patients on novel agents, usually occurring as an early event. RT incidence is lower in CLL patients treated with novel agents in the front line compared to relapsed/refractory cases, with a higher incidence in patients with TP53 disruption. The genetic heterogeneity and complexity are higher in RT-DLBCL than CLL; the genetics of RT-HL are largely unknown. In addition to TP53, aberrations in CDKN2A, MYC, and NOTCH1 are common in RT-DLBCL; however, no distinct RT-specific genetic aberration is recognised yet. RT-DLBCL on ibrutinib is frequently associated with BTK and PLCG2 mutations. Here, we update on genetic analysis, diagnostics and treatment options in RT in the era of novel agents.

Comparative Analysis of BTK Inhibitors and Mechanisms Underlying Adverse Effects

The cytoplasmic protein-tyrosine kinase BTK plays an essential role for differentiation and survival of B-lineage cells and, hence, represents a suitable drug target. The number of BTK inhibitors (BTKis) in the clinic has increased considerably and currently amounts to at least 22. First-in-class was ibrutinib, an irreversible binder forming a covalent bond to a cysteine in the catalytic region of the kinase, for which we have identified 228 active trials listed at ClinicalTrials.gov. Next-generation inhibitors, acalabrutinib and zanubrutinib, are approved both in the United States and in Europe, and zanubrutinib also in China, while tirabrutinib is currently only registered in Japan. In most cases, these compounds have been used for the treatment of B-lymphocyte tumors. However, an increasing number of trials instead addresses autoimmunity and inflammation in multiple sclerosis, rheumatoid arthritis, pemphigus and systemic lupus erythematosus with the use of either irreversibly binding inhibitors, e.g., evobrutinib and tolebrutinib, or reversibly binding inhibitors, like fenebrutinib. Adverse effects (AEs) have predominantly implicated inhibition of other kinases with a BTKi-binding cysteine in their catalytic domain. Analysis of the reported AEs suggests that ibrutinib-associated atrial fibrillation is caused by binding to ERBB2/HER2 and ERBB4/HER4. However, the binding pattern of BTKis to various additional kinases does not correlate with the common assumption that skin manifestations and diarrhoeas are off-target effects related to EGF receptor inhibition. Moreover, dermatological toxicities, diarrhoea, bleedings and invasive fungal infections often develop early after BTKi treatment initiation and subsequently subside. Conversely, cardiovascular AEs, like hypertension and various forms of heart disease, often persist.

The Right Dose: From Phase I to Clinical Practice

To realize the full potential of promising new anticancer drugs, it is of paramount importance to administer them at the right dose. The aim of this educational article is to provide several opportunities to optimize anticancer drug dosing, focusing on oral targeted therapies. First, therapeutic drug monitoring can optimize exposure in individual patients, if the optimal concentration is known. This approach is of particular interest in regard to oral kinase inhibitors with high interindividual pharmacokinetic variability. If exposure is related to response, then therapeutic drug monitoring is potentially feasible, although the clinical utility of this approach has not yet been established. Other approaches to reduce variability include administration of more frequent, smaller doses and administration under optimal prandial conditions. However, for many drugs, the labeled dose has not been demonstrated to be the optimal dose; for such agents, the vast majority of patients may be receiving excessive doses, which results in excessive toxicity. Furthermore, administration of lower off-label doses may reduce both medical and financial toxicity. These strategies should be applied from registration studies to clinical practice, with the goal of better optimizing anticancer treatment.

Richter Syndrome

PURPOSE OF REVIEW

Richter syndrome (RS) is an uncommon but aggressive evolution of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). RS is an unmet clinical need in the field of CLL. Recent advances in understanding the biology of this condition provide the rationale for testing new therapeutic concepts in order to improve the outcome of patients developing RS, which is so far poor. In this review, we summarize disease characteristics and available therapeutic options for RS.

RECENT FINDINGS

Current regimens with novel agents in monotherapy have shown little impact on survival. Nevertheless, the better reported outcome for RS has been achieved with the combination of chemo-immunotherapy with a novel agent, confirming the synergistic effect of the approaches. Still, the frailty of this population may impose a less toxic management leaving most patients with no reasonable therapeutic option. Treatment options for RS need to be further expanded. Preclinical models in current development may allow to explore actionable pathways and identify new drug targeted combinations.

Is There a Role for Chemotherapy in the Era of Targeted Therapies?

PURPOSE OF REVIEW

The treatment landscape of chronic lymphocytic leukemia has been rapidly evolving over the past few years. The prior standard of care, chemoimmunotherapy, is being replaced by targeted agents, and the utility of chemotherapy has come under question. In this review, we examine recent data comparing chemoimmunotherapy to targeted agents, how these data impact clinical management, and whether there are potential future roles for cytotoxic chemotherapy.

RECENT FINDINGS

Clinical trials have shown improved clinical outcomes with targeted agents compared to traditional chemoimmunotherapy. Based on these data, the current treatment paradigm primarily favors targeted agents over chemoimmunotherapy, with a few exceptions. However, targeted agents have notable limitations, and thus, there may be a future role of cytotoxic chemotherapy when administered in combination with targeted agents. Although targeted agents have nearly replaced chemoimmunotherapy in the treatment of chronic lymphocytic leukemia, novel combinations utilizing chemotherapy are being developed that may lead to better outcomes.

The impact of early discontinuation/dose modification of venetoclax on outcomes in patients with relapsed/refractory chronic lymphocytic leukemia: post-hoc analyses from the phase III MURANO study

Fixed-duration venetoclax plus rituximab (VenR) has a manageable safety profile and improves survival in patients with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). We present data from the phase III MURANO study on the impact of venetoclax modification or premature discontinuation on outcomes in patients with R/R CLL. Time-dependent Cox proportional hazards regression models, stratified by 17p deletion and risk status, evaluated the impact of venetoclax discontinuation/modification on investigator-assessed progression-free survival (PFS) and overall survival (OS). Analyses were performed retrospectively (without type-1 error control) in intention-to-treat patients from the VenR arm of MURANO. Overall, 140/194 (72%) patients in the VenR arm completed 2 years of therapy; 54/194 (28%) patients prematurely discontinued treatment. Inferior PFS was observed in patients prematurely discontinuing venetoclax for any reason (disease progression excluded; p

Current Treatment of Refractory/Relapsed Chronic Lymphocytic Leukemia: A Focus on Novel Drugs

Recently, the use of novel targeted drugs has changed the treatment paradigms in chronic lymphocytic leukemia (CLL). Among the several drugs used for the management of relapsed/refractory (R/R) CLL, Bruton tyrosine kinase inhibitors (ibrutinib and acalabrutinib), phosphatidylinositol 3-kinase inhibitors (idelalisib and duvelisib), B-cell lymphoma 2 inhibitor (venetoclax), and novel CD20 monoclonal antibodies have demonstrated the greatest improvements in survival among R/R CLL patients. However, patients with relapsed but asymptomatic CLL do not need immediate alternative treatment and should be observed until evident sign of progression. Among available approved treatments, venetoclax + rituximab for 24 months or ibrutinib as continuous therapy is recommended. Another, less recommended, option is idelalisib in combination with rituximab. The correct treatment selection depends on the type of prior therapy, response to previous treatment and side effects, presence of comorbidities, and the risk of drug toxicity. Allogeneic hematopoietic stem cell transplantation and investigational therapies such as chimeric antigen receptor-T-cell therapy are promising treatment options for high-risk patients, including those progressing after 1 or more targeted therapies. The present review discusses current treatment strategies for patients with R/R CLL.

Acalabrutinib monotherapy in patients with relapsed/refractory chronic lymphocytic leukemia: updated phase 2 results

Therapeutic targeting of Bruton tyrosine kinase (BTK) has dramatically improved survival outcomes for patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Acalabrutinib is an oral, highly selective BTK inhibitor that allows for twice-daily dosing due to its selectivity. In this phase 1b/2 study, 134 patients with relapsed/refractory CLL or SLL (median age, 66 years [range, 42-85 years]; median prior therapies, 2 [range, 1-13]) received acalabrutinib 100 mg twice daily for a median of 41 months (range, 0.2-58 months). Median trough BTK occupancy at steady state was 97%. Most adverse events (AEs) were mild or moderate, and were most commonly diarrhea (52%) and headache (51%). Grade ≥3 AEs (occurring in ≥5% of patients) were neutropenia (14%), pneumonia (11%), hypertension (7%), anemia (7%), and diarrhea (5%). Atrial fibrillation and major bleeding AEs (all grades) occurred in 7% and 5% of patients, respectively. Most patients (56%) remain on treatment; the primary reasons for discontinuation were progressive disease (21%) and AEs (11%). The overall response rate, including partial response with lymphocytosis, with acalabrutinib was 94%; responses were similar regardless of genomic features (presence of del(11)(q22.3), del(17)(p13.1), complex karyotype, or immunoglobulin variable region heavy chain mutation status). Median duration of response and progression-free survival (PFS) have not been reached; the estimated 45-month PFS was 62% (95% confidence interval, 51% to 71%). BTK mutation was detected in 6 of 9 patients (67%) at relapse. This updated and expanded study confirms the efficacy, durability of response, and long-term safety of acalabrutinib, justifying its further investigation in previously untreated and treated patients with CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02029443.

Disease Flare During Temporary Interruption of Ibrutinib Therapy in Patients with Chronic Lymphocytic Leukemia

BACKGROUND

Approximately 25% of patients with chronic lymphocytic leukemia (CLL) experience a flare of disease following ibrutinib discontinuation. A critical question is whether this phenomenon may also occur when ibrutinib is temporarily held. This study aimed to determine the frequency and characteristics of disease flares in this setting and assess risk factors and clinical outcomes.

MATERIALS AND METHODS

We identified all patients with CLL seen at Mayo Clinic between October 2012 and March 2019 who received ibrutinib. Temporary interruptions in treatment and associated clinical findings were ascertained.

RESULTS

Among the 372 patients identified, 143 (38%) had at least one temporary interruption (median 1 hold, range 1-7 holds) in treatment. The median duration of interruption was 8 days (range 1-59 days) and the most common indication was periprocedural. Among the 143 patients with ≥1 hold, an associated disease flare was seen in 35 (25%) patients: mild (constitutional symptoms only) in 21 patients and severe (constitutional symptoms with exam/radiographic findings or laboratory changes) in 14 patients. Disease flare resolved with resuming ibrutinib in all patients. Predictive factors of disease flare included progressive disease at time of hold and ≥ 24 months of ibrutinib exposure. The occurrence of disease flare with an ibrutinib hold was associated with shorter event-free survival (hazard ratio 2.3; 95% confidence interval 1.3-4.1; p = .007) but not overall survival.

CONCLUSION

Temporary interruptions in ibrutinib treatment of patients with CLL are common, and one quarter of patients who held ibrutinib in this study experienced a disease flare. Resolution with resuming ibrutinib underscores the importance of awareness of this phenomenon for optimal management.

IMPLICATIONS FOR PRACTICE

Ibrutinib is a very effective treatment for chronic lymphocytic leukemia (CLL) but needs to be taken continuously. Side effects, such as increased bleeding risk with procedures, require temporary interruptions in this continuous treatment. Rapid CLL progression following ibrutinib discontinuation has been increasingly recognized. This study demonstrates that similar flares in disease signs or symptoms may occur during ibrutinib holds as well. Importantly, management with restarting ibrutinib led to quick clinical improvement. Awareness of this phenomenon among clinicians is critical to avoid associated patient morbidity and premature cessation of effective treatment with ibrutinib if the flare is misidentified as true progression of disease.

Targeted Therapy in Chronic Lymphocytic Leukemia

Despite a prevailing view that advances in cancer therapy will come through selective targeting of enzymes encoded by mutated oncogenes responsible for the neoplastic phenotype, recent advances in the treatment of patients with chronic lymphocytic leukemia (CLL) have instead exploited knowledge of its biology. Indeed, CLL cells depend on interactions with cells and soluble factors present in the tumor microenvironment for proliferation and survival. B-cell receptor signaling and chemokine-receptor signaling play prominent roles. Elucidation of these signaling pathways has defined physiologic targets for drugs, such as ibrutinib, which inhibit Bruton tyrosine kinase and are therapeutically effective. The characteristic high-level expression of BCL2 in CLL that can enhance leukemia-cell survival has now become an Achilles heel targeted by clinically effective drugs such as venetoclax. Here we discuss advances in such targeted therapy and highlight other disease attributes, such as the distinctive expression of ROR1, which may be targeted for clinical benefit, alone or in combination with other targeted therapies.

Ibrutinib dose modifications in the management of CLL

Background

Ibrutinib is a Bruton tyrosine kinase inhibitor approved for the treatment of chronic lymphocytic leukemia (CLL) in 2014. Ibrutinib is often used to treat patients who are younger than the patients originally included in theclinical trials have additional unfavorable prognostic factors and suffer from additional comorbidities excluded from the original phase III trials. Our objective was to examine current clinical practices and their impact in this expanded population of CLL patients who often require adjustments in the standard prescribed dose and schedule of therapy.

Materials and methods

An extensive review of the medical literature was conducted to establish the consensus on ibrutinib dose modifications in patients with CLL. Twenty-nine studies were reviewed including fourteen clinical trials and fifteen “real-world practice” studies.

Results

The average discontinuation rate was similar between clinical trials and “real-world practice” studies though the reasons for discontinuation differed. CLL progression was a more common reason for discontinuation in clinical trial studies while toxicity was a more common reason for discontinuation in “real-world practice” studies. Some studies have suggested worse outcomes in patients requiring dose reductions in ibrutinib while others have shown no change in treatment efficacy in patients requiring dose reductions due to concomitant CYP medications or increased immunosuppression post-transplant.

Conclusion

The impact of ibrutinib dose modifications on clinical outcome remains unclear. Patients on concomitant CYP3A inhibitors should be prescribed a lower dose than the standard 420 mg daily, in order to maintain comparable pharmacologic properties. Further research is required to establish definitive clinical practice guidelines.