Long-Term Efficacy and Safety of Ibrutinib in the Treatment of CLL Patients: A Real Life Experience

Management of infections for patient treated with ibrutinib in clinical practice

Ibrutinib, a highly effective inhibitor of the Bruton tyrosine kinase, has significantly transformed the therapeutic approach in chronic lymphocytic leukemia (CLL). Despite these advancements, the disease continues to be characterized by immune dysfunction and increased susceptibility to infections, with mortality rates from infections showing no significant improvement over the past few decades. Therefore, timely prevention, recognition, and treatment of infections remains an important aspect of the standard management of a patient with CLL. A panel of hematologists with expertise in CLL met to discuss existing literature and clinical insights for the management of infectious in CLL undergoing ibrutinib treatment. Despite not being a fully comprehensive review on the topic, this work provides a set of practical recommendations that can serve as a guide to healthcare professionals who manage these patients in their daily clinical practice.

BTK acts as a modulator of the response to imatinib in chronic myeloid leukemia

The use of tyrosine kinase inhibitors, such as imatinib, against the chronic myeloid leukemia (CML)-causing kinase BCR::ABL1 has become the model for successful targeted therapy. Nevertheless, drug resistance remains a clinical problem. Analysis of genome-wide expression and genetic aberrations of an in vitro imatinib-resistant CML cell line revealed downregulation of Bruton's tyrosine kinase (BTK), predominantly associated with B cell malignancies, and a novel BTK kinase domain variant in imatinib resistance. This raised the question of the role of BTK in imatinib-resistant CML. In the present study, BTK downregulation and the presence of the BTK variant c.1699_1700delinsAG p.(Glu567Arg) were confirmed in imatinib resistance in vitro. Similarly, BTK inhibition or small interfering RNA-mediated BTK knockdown reduced imatinib susceptibility by 84 and 71%, respectively. BTK overexpression was detrimental to CML cells, as proliferation was significantly reduced by 20.5% under imatinib treatment. In addition, BTK rescue in imatinib-resistant cells restored imatinib sensitivity. The presence of the BTK p.(Glu567Arg) variant increased cell numbers (57%) and proliferation (37%) under imatinib exposure. These data demonstrate that BTK is important for the development of imatinib resistance in CML: Its presence increased drug response, while its absence promotes imatinib resistance. Moreover, the BTK p.(Glu567Arg) variant abrogates imatinib sensitivity. These findings demonstrate a context-dependent role for BTK as an oncogene in B cell malignancies, but as a tumor suppressor in other neoplasms.

Covalent Macrocyclic Proteasome Inhibitors Mitigate Resistance in Plasmodium falciparum

The Plasmodium proteasome is a promising antimalarial drug target due to its essential role in all parasite lifecycle stages. Furthermore, proteasome inhibitors have synergistic effects when combined with current first-line artemisinin and related analogues. Linear peptides that covalently inhibit the proteasome are effective at killing parasites and have a low propensity for inducing resistance. However, these scaffolds generally suffer from poor pharmacokinetics and bioavailability. Here we describe the development of covalent, irreversible, macrocyclic inhibitors of the Plasmodium falciparum proteasome. We identified compounds with excellent potency and low cytotoxicity; however, the first generation suffered from poor microsomal stability. Further optimization of an existing macrocyclic scaffold resulted in an irreversible covalent inhibitor carrying a vinyl sulfone electrophile that retained high potency and low cytotoxicity and had acceptable metabolic stability. Importantly, unlike the parent reversible inhibitor that selected for multiple mutations in the proteasome, with one resulting in a 5,000-fold loss of potency, the irreversible analogue only showed a 5-fold loss in potency for any single point mutation. Furthermore, an epoxyketone analogue of the same scaffold retained potency against a panel of known proteasome mutants. These results confirm that macrocycles are optimal scaffolds to target the malarial proteasome and that the use of a covalent electrophile can greatly reduce the ability of the parasite to generate drug resistance mutations.

Which is the top player for the cardiovascular safety? ibrutinib vs. obinutuzumab in CLL

Introduction: Ibrutinib, a Bruton's tyrosine kinase (BTK) inhibitor, is authorized for the treatment of chronic lymphocytic leukemia (CLL). This study aims to explore the cardiac safety profile of ibrutinib in comparison with obinutuzumab. Methods: A retrospective pharmacovigilance study was conducted on data retrieved from the European pharmacovigilance database (Eudravigilance) from 1 January 2014 to 30 September 2022. To compare the reporting frequency of cardiovascular events among ibrutinib, obinutuzumab, and the combination of both. Results: A total of 2 291 CV cases were retrieved, of which 1965 were related to ibrutinib, 312 to obinutuzumab, and 14 to the combination. Most cases referred to patients aged ≥65 years (N = 1,454; 63.47%) and male (N = 1,497; 65.34%). Most cases were serious (N = 2,131; 93.02%). The most reported events were: atrial fibrillation (N = 913; 31.31%) and haemorrhage (N = 201; 6.89%). A higher reporting frequency of CV events was found when ibrutinib was compared to obinutuzumab (ROR, 3.22; 95% CI, 2.89-3.60) or combination (ROR, 1.77; 95% CI, 1.11-2.83). A lower reporting was observed when obinutuzumab was compared to combination (ROR, 0.55; 95% CI, 0.34-0.88). Discussion: A higher reporting frequency of CV events in patients exposed to ibrutinib in comparison with obinutuzumab was found. Further studies are needed to better explore the safety of ibrutinib.

Real-world treatment outcomes of medicines used in special situations (off-label and compassionate use) in oncology and hematology: A retrospective study from a comprehensive cancer institution

PURPOSE

Medicines in special situations (MSS) refer to off-label or to unlicensed drugs under investigation (compassionate use). Our objectives were to evaluate characteristics and to estimate overall survival (OS), event-free survival (EFS), and the duration of treatment (DT) of MSS used for cancer treatment at a multicentre comprehensive cancer institution.

METHODS

Retrospective cohort study on adult cancer patients for whom an MSS treatment was requested (January 2011-December 2020). A descriptive analysis was performed and median OS and EFS and 95% confidence intervals (CIs) were estimated. Survival curves were stratified by type of tumor, ECOG (Eastern Cooperative Oncology Group) performance status (PS), age, sex, treatment stage and type of drug (mechanism of action and target).

RESULTS

Treatment was initiated in 2092 episodes (1930 patients) out of 2377 MSS episodes (2189 patients) requested, 33% for hematological treatment and 87% for advanced stage cancer. Median OS (months) was 21.1 (95% CI 19.4-22.7), median EFS was 5.6 (95% CI 5.1-6.0) months, and median DT was 4.5 [0.0; 115.3] months. OS and EFS statistically significantly favored female patients, ECOG PS ≥2 episodes showed worse OS and EFS outcomes (p < 0.0001). Statistically significant differences in survival were found within solid and hematological cancer, disease stage, drug mechanism of action, and type of cancer (p < 0.001) but not for age. Survival outcomes by tumor subtype and drug are presented both globally and separately based on disease stage.

CONCLUSION

MSS uses are practiced across almost all cancer types, mostly for advanced disease. ECOG PS ≥2, along with advanced disease, was related to worse survival. Information about real-world outcomes is valuable and contributes to better decision-making regarding MSS and our experience in this field could be of interest for other colleagues.

Real-World Clinical Outcomes and Adverse Events in Patients with Chronic Lymphocytic Leukemia Treated with Ibrutinib: A Single-Center Retrospective Study

Background and Objectives: The treatment of chronic lymphocytic leukemia (CLL) has acquired new targeted therapies. In clinical trials, ibrutinib improved outcomes safely. Real-world data called for a reappraisal of ibrutinib strategies. We report on a single center's experience with ibrutinib monotherapy, aiming to explore the outcomes, tolerability, and prognosis of CLL patients in routine clinical practice. Materials and Methods: Data were collected from all CLL patients treated with ibrutinib at Fundeni Clinical Institute, Bucharest, Romania, between January 2016 and June 2021. Results: A total of one hundred twenty-three CLL adult patients were treated with ibrutinib. Of the patients, 87% had relapsed/refractory CLL. The median age at ibrutinib initiation was 65 years; 44.7% of patients were staged Rai III/IV. At 32-month median follow-up, the median progression-free survival (PFS) was 50 months, the overall survival (OS) was not reached, and the overall response rate (ORR) was 86.2%. The age or number of previous therapies did not impact outcomes or tolerability. An Eastern Cooperative Oncology Group performance status (ECOG PS) score ≥ 2 and shorter time from initiation of last therapy (TILT) before ibrutinib predicted inferior PFS. Baseline characteristics had no impact on the OS except for TILT in R/R CLL patients. Drug-related adverse events (AEs) of any grade and grade ≥ 3 AEs were reported in 82.1% and 30.9% of the patients, respectively. Infections were the most common AEs (29.3%). Drug discontinuation was permanent in 43.9% of patients, mainly due to disease progression (17.1%) and toxicity (8.9%). Patients with a Cumulative Illness Rating Scale (CIRS) score ≥ 6 had a higher risk for toxicity-related discontinuation. An ECOG PS ≥ 2 predicted an increased rate of permanent discontinuation and grade ≥ 3 AEs. Conclusions: The outcomes of this study align with the results from ibrutinib clinical trials. Our study demonstrated that poor patient fitness, early relapse before ibrutinib, and permanent ibrutinib discontinuation are essential outcome determinants. Patient comorbidity burden and fitness were significant predictors for ibrutinib intolerance.