Ibrutinib versus previous standard of care: an adjusted comparison in patients with relapsed/refractory chronic lymphocytic leukaemia

Approaches to Selecting "Time Zero" in External Control Arms with Multiple Potential Entry Points: A Simulation Study of 8 Approaches

BACKGROUND

When including data from an external control arm to estimate comparative effectiveness, there is a methodological choice of when to set "time zero," the point at which a patient would be eligible/enrolled in a contemporary study. Where patients receive multiple lines of eligible therapy and thus alternative points could be selected, this issue is complex.

METHODS

A simulation study was conducted in which patients received multiple prior lines of therapy before entering either cohort. The results from the control and intervention data sets are compared using 8 methods for selecting time zero. The base-case comparison was set up to be biased against the intervention (which is generally received later), with methods compared in their ability to estimate the true intervention effectiveness. We further investigate the impact of key study attributes (such as sample size) and degree of overlap in time-varying covariates (such as prior lines of therapy) on study results.

RESULTS

Of the 8 methods, 5 (all lines, random line, systematically selecting groups based on mean absolute error, root mean square error, or propensity scores) showed good performance in accounting for differences between the line at which patients were included. The first eligible line can be statistically inefficient in some situations. All lines (with censoring) cannot be used for survival outcomes. The last eligible line cannot be recommended.

CONCLUSIONS

Multiple methods are available for selecting the most appropriate time zero from an external control arm. Based on the simulation, we demonstrate that some methods frequently perform poorly, with several viable methods remaining. In selecting between the viable methods, analysts should consider the context of their analysis and justify the approach selected.

HIGHLIGHTS

There are multiple methods available from which an analyst may select "time zero" in an external control cohort.This simulation study demonstrates that some methods perform poorly but most are viable options, depending on context and the degree of overlap in time zero across cohorts.Careful thought and clear justification should be used when selecting the strategy for a study.

Real-World Characteristics and Outcome of Patients Treated With Single-Agent Ibrutinib for Chronic Lymphocytic Leukemia in Spain (IBRORS-LLC Study)

BACKGROUND

Ibrutinib demonstrated remarkable efficacy and favorable tolerability in patients with untreated or relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL), including those with high-risk genetic alterations. The IBRORS-CLL study assessed the characteristics, clinical management and outcome of CLL patients receiving ibrutinib in routine clinical practice in Spain.

PATIENTS

Observational, retrospective, multicenter study in CLL patients who started single-agent ibrutinib as first-line treatment or at first or second relapse between January 2016 and January 2019.

RESULTS

A total of 269 patients were included (median age: 70.9 years; cardiovascular comorbidity: 55.4%, including hypertension [47.6%] and atrial fibrillation [AF] [7.1%]). Overall, 96.7% and 69% of patients underwent molecular testing for del(17p)/TP53 mutation and IGHV mutation status. High-risk genetic features included unmutated IGHV (79%) and del(17p)/TP53 mutation (first-line: 66.3%; second-line: 23.1%). Overall, 84 (31.2%) patients received ibrutinib as first-line treatment, and it was used as second- and third-line therapy in 121 (45.0%) and 64 (23.8%) patients. The median progression-free survival and overall survival were not reached irrespective of del(17p)/TP53, or unmutated IGHV. Common grade ≥3 adverse events were infections (12.2%) and bleeding (3%). Grade ≥3 AF occurred in 1.5% of patients.

CONCLUSION

This real-world study shows that single-agent ibrutinib is an effective therapy for CLL, regardless of age and high-risk molecular features, consistent with clinical trials. Additionally, single-agent ibrutinib was well tolerated, with a low rate of cardiovascular events. This study also emphasized a high molecular testing rate of del(17p)/TP53 mutation and IGHV mutation status in clinical practice according to guideline recommendations.

Single-agent ibrutinib in RESONATE-2™ and RESONATE™ versus treatments in the real-world PHEDRA databases for patients with chronic lymphocytic leukemia

After analyzing treatment patterns in chronic lymphocytic leukemia (CLL) (objective 1), we investigated the relative effectiveness of ibrutinib versus other commonly used treatments (objective 2) in patients with treatment-naïve and relapsed/refractory CLL, comparing patient-level data from two randomized registration trials with two real-world databases. Hazard ratios (HR) and 95% confidence intervals (CIs) were estimated using a multivariate Cox proportional hazards model, adjusted for differences in baseline characteristics. Rituximab-containing regimens were often prescribed in clinical practice. The most frequently prescribed regimens were fludarabine + cyclophosphamide + rituximab (FCR, 29.3%), bendamustine + rituximab (BR, 17.7%), and other rituximab-containing regimens (22.0%) in the treatment-naïve setting (n = 604), other non-FCR/BR rituximab-containing regimens (38.7%) and non-rituximab–containing regimens (28.5%) in the relapsed/refractory setting (n = 945). Adjusted HRs (95% CI) for progression-free survival (PFS) and overall survival (OS), respectively, with ibrutinib versus real-world regimens were 0.23 (0.14–0.37; p < 0.0001) and 0.40 (0.22–0.76; p = 0.0048) in the treatment-naïve setting, and 0.21 (0.16–0.27; p < 0.0001) and 0.29 (0.21–0.41; p < 0.0001) in the relapsed/refractory setting. When comparing real-world use of ibrutinib (n = 53) versus other real-world regimens in relapsed/refractory CLL (objective 3), adjusted HRs (95% CI) were 0.37 (0.22–0.63; p = 0.0003) for PFS and 0.53 (0.27–1.03; p < 0.0624) for OS. This adjusted analysis, based on nonrandomized patient data, suggests ibrutinib to be more effective than other commonly used regimens for CLL.

A review of chimeric antigen receptor T-cells in lymphoma

Introduction: Immunotherapy has revolutionized the treatment of cancer. Antibodies, antibody drug conjugates, and bispecific antibodies have improved outcomes in various cancers especially lymphomas. Chimeric antigen receptor T cell (CAR-T) is a step forward in the immunotherapy paradigm for the treatment of Lymphomas. Recently, two CAR-T products, Tisagenlecleucel and Axicabtagene ciloleucel, were approved by the US FDA. While it is exciting to have such novel treatment available, the challenges of production, administration, related toxicity, and cost remain. Specific toxicities related to CAR-T like Cytokine Release Syndrome (CRS) and Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS) could be fatal and need close monitoring and prompt treatment to avoid mortality and improve efficacy of the treatment. Areas covered: In this article, the authors discuss receptor constructs, administration, toxicities, efficacy and reimbursement of CAR-T treatment. Expert opinion: Since approval of CAR-T treatment, cost of therapy and reimbursement have been a big challenge in implementation of CAR-T. This has triggered cost-effective analysis and nationwide discussions about the reimbursement process of such treatment. In spite of these challenges, CAR-T treatment is a huge step forward with a very bright future. Novel CAR-T targeting a variety of antigens in different cancers seems promising in near future.

Ibrutinib in the management of Waldenstrom macroglobulinemia

Bruton tyrosine kinase plays a critical role in hastening cell proliferation. Bruton tyrosine kinase inhibitors are a class of immunotheraputic agents that disrupt this signaling pathway. Ibrutinib, a novel Bruton tyrosine kinase inhibitor approved by the Food and Drug Administration (FDA) for the treatment of Waldenstrom macroglobulinemia in patients who have failed treatment with other agents, has emerged as an important therapeutic agent in the management of Waldenstrom macroglobulinemia and other plasma cell dyscrasias. Ibrutinib has shown to increase progression free survival and improve overall mortality. We present a review of ibrutinib, beginning with an overview of the Bruton tyrosine kinase pathway and clinically relevant gene mutations impacting treatment and prognosis for patients with Waldenstrom macroglobulinemia, followed by evidence supporting therapeutic indications for ibrutinib, and detailing its safety and efficacy evidence, current clinical guidelines, adverse effects and their management, and finally challenges of drug resistance. We also present findings on newly developed Bruton tyrosine kinase inhibitors in the therapeutic pipeline to provide readers insight into this rapidly evolving corner of oncology pharmacy practice.

Efficacy of bendamustine and rituximab as first salvage treatment in chronic lymphocytic leukemia and indirect comparison with ibrutinib: a GIMEMA, ERIC and UK CLL FORUM study

We performed an observational study on the efficacy of ben-damustine and rituximab (BR) as first salvage regimen in chronic lymphocytic leukemia (CLL). In an intention-to-treat analysis including 237 patients, the median progression-free survival (PFS) was 25 months. The presence of del(17p), unmutated IGHV and advanced stage were associated with a shorter PFS at multivariate analysis. The median time-to-next treatment was 31.3 months. Front-line treatment with a chemoimmunotherapy regimen was the only predictive factor for a shorter time to next treatment at multivariate analysis. The median overall survival (OS) was 74.5 months. Advanced disease stage (i.e. Rai stage III-IV or Binet stage C) and resistant disease were the only parameters significantly associated with a shorter OS. Grade 3-5 infections were recorded in 6.3% of patients. A matched-adjusted indirect comparison with ibrutinib given second-line within Named Patient Programs in the United Kingdom and in Italy was carried out with OS as objective end point. When restricting the analysis to patients with intact 17p who had received chemoimmunotherapy in first line, there was no difference in OS between patients treated with ibrutinib (63% alive at 36 months) and patients treated with BR (74.4% alive at 36 months). BR is an efficacious first salvage regimen in CLL in a real-life population, including the elderly and unfit patients. BR and ibrutinib may be equally effective in terms of OS when used as first salvage treatment in patients without 17p deletion.

Mammalian Plakins, Giant Cytolinkers: Versatile Biological Functions and Roles in Cancer

Cancer is a highly lethal disease that is characterized by aberrant cell proliferation, migration, and adhesion, which are closely related to the dynamic changes of cytoskeletons and cytoskeletal-adhesion. These will further result in cell invasion and metastasis. Plakins are a family of giant cytolinkers that connect cytoskeletal elements with each other and to junctional complexes. With various isoforms composed of different domain structures, mammalian plakins are broadly expressed in numerous tissues. They play critical roles in many cellular processes, including cell proliferation, migration, adhesion, and signaling transduction. As these cellular processes are key steps in cancer development, mammalian plakins have in recent years attracted more and more attention for their potential roles in cancer. Current evidence shows the importance of mammalian plakins in various human cancers and demonstrates mammalian plakins as potential biomarkers for cancer. Here, we introduce the basic characteristics of mammalian plakins, review the recent advances in understanding their biological functions, and highlight their roles in human cancers, based on studies performed by us and others. This will provide researchers with a comprehensive understanding of mammalian plakins, new insights into the development of cancer, and novel targets for cancer diagnosis and therapy.

Microtubule-Actin Crosslinking Factor 1 and Plakins as Therapeutic Drug Targets

Plakins are a family of seven cytoskeletal cross-linker proteins (microtubule-actin crosslinking factor 1 (MACF), bullous pemphigoid antigen (BPAG1) desmoplakin, envoplakin, periplakin, plectin, epiplakin) that network the three major filaments that comprise the cytoskeleton. Plakins have been found to be involved in disorders and diseases of the skin, heart, nervous system, and cancer that are attributed to autoimmune responses and genetic alterations of these macromolecules. Despite their role and involvement across a spectrum of several diseases, there are no current drugs or pharmacological agents that specifically target the members of this protein family. On the contrary, microtubules have traditionally been targeted by microtubule inhibiting agents, used for the treatment of diseases such as cancer, in spite of the deleterious toxicities associated with their clinical utility. The Research Collaboratory for Structural Bioinformatics (RCSB) was used here to identify therapeutic drugs targeting the plakin proteins, particularly the spectraplakins MACF1 and BPAG1, which contain microtubule-binding domains. RCSB analysis revealed that plakin proteins had 329 ligands, of which more than 50% were MACF1 and BPAG1 ligands and 10 were documented, clinically or experimentally, to have several therapeutic applications as anticancer, anti-inflammatory, and antibiotic agents.

Ibrutinib and its use in the treatment of chronic lymphocytic leukemia

Ibrutinib represents a revolution in chronic lymphocytic leukemia treatment scenario providing results never seen before and offering an effective therapy even in high-risk patients with really poor outcome after chemoimmunotherapy. Thanks to longer updates, on one hand, ibrutinib has confirmed its efficacy continuing to show clinical benefits over time; on the other hand, resistance mechanisms are slowly emerging. Moreover, clinicians should be aware of ibrutinib-related side effects, paying attention to screen patients that could benefit more from the drug and try to prevent adverse events. While ibrutinib approval indication is expanding, high treatment costs will shortly require a selection of those who can really draw advantage from Bruton's tyrosine kinase inhibition and those who could continue to be treated with chemoimmunotherapy.