Improved survival outcomes with the addition of rituximab to initial therapy for chronic lymphocytic leukemia: a comparative effectiveness analysis in the province of British Columbia, Canada

Epidemiology of chronic lymphocytic leukemia in Chilean and Amerindian population in Chile

The study aim was to analyze incidence and presentation features of chronic lymphocytic leukemia (CLL) in Chile, in Amerindian population and in non-Native. Between 2012 and 2019, 912 patients were diagnosed, and 13 (1.4%) were Amerindian. The estimated incidence in Chilean population was 1.17/100,000 person per year, while in Amerindian, 0.09/100,000 person per year. Median age was 73 years. At diagnosis, 48, 27, and 25%, had low (0), intermediate (I/II) and high-risk (III/IV) disease on Rai classification. Diagnostic immunophenotypic Matutes score was ≥4 in 90%. Median follow-up was 37 months (range 2-87). 5-year OS was 56%, with median overall survival (OS) not reached. It was worse in men, ≥65 years, high-risk and those with increased prolymphocytes (CLL/PL). This study shows low incidence and worse OS in Chilean CLL patients, compared to those from European countries, despite similar clinical features. It also demonstrates that CLL is very uncommon in Amerindian population.

Impact of age and treatment institution type on outcomes of patients treated for chronic lymphocytic leukemia in British Columbia, Canada

Older age has been shown to adversely impact overall survival (OS) in chronic lymphocytic leukemia (CLL) however, prior population-based studies did not analyze the impact of cytogenetic abnormalities or were prior to the availability of ibrutinib.

OBJECTIVES

i) We sought to compare outcomes of patients based on their age at treatment to examine if older age has an impact on OS in patients who were treated during the period when fludarabine-rituximab was the standard upfront therapy and when ibrutinib was first introduced and ii) compare outcomes based on whether the patient received primary treatment at an academic or community-based centre.

METHODS

The BC Provincial CLL Database, a population-based databasewas used to include patients who have received treatment in British Columbia (BC), Canada between 2004 and 2016.

RESULTS

A total of 1122 patients were included (<70 years at treatment, n = 589) with median age at diagnosis 66 years. Younger patients had higher Rai stage (55% vs. 44% stage I-II, p < 0.001), higher lymphocyte count at diagnosis (13 × 10⁹/L vs. 10 × 10⁹/L, p = 0.004), greater proportion with B-symptoms at diagnosis (15% vs 10%, p = 0.004), shorter time from diagnosis to treatment (13.9 months vs. 21.4 months, p = 0.001), higher proportion treated at an academic centre (79% vs. 69%, p < 0.001) and more were treated with fludarabine-rituximab or FCR (69% vs. 42%, p < 0.001) compared to older patients. Older patients had both a significantly (p < 0.001) shorter OS from treatment start (4.7 years) and disease specific survival (8.1 years) than younger patients (median OS and DSS not reached). Of interest, there was no difference in OS between patients treated at an academic centre or community centre (p = 0.087). First-line treatment with chemoimmunotherapy improved OS (HR 0.465, 95% CI: 0.381-.567).

CONCLUSIONS

Older age but not treatment-institution type adversely impacts overall survival and CLL survival in treated patients in BC.

Possible hampered effectiveness of second-line treatment with rituximab-containing chemotherapy without signs of rituximab resistance: a population-based study among patients with chronic lymphocytic leukemia

Rituximab-containing chemotherapy remains a viable frontline treatment option for patients with chronic lymphocytic leukemia (CLL) in the era of novel agents. However, its effectiveness in the second-line setting-in relation to previous rituximab exposure in first-line-has hardly been evaluated in a population-based setting. Therefore, in this comprehensive, population-based study, we assessed the impact of first-line treatment with rituximab-containing chemotherapy on the effectiveness of second-line treatment with rituximab-containing chemotherapy. We selected all 1735 patients diagnosed with CLL between 2004 and 2010 from the Dutch Population-based HAematological Registry for Observational Studies (PHAROS). The primary endpoint was treatment-free survival (TFS). First- and second-line treatment was instituted in 663 (38%) and 284 (43%) patients, respectively. In first line, the median TFS was 19.7 and 67.1 months for chemotherapy without (n = 445; 67%) and with rituximab (n = 218; 33%), respectively (adjusted hazard ratio [HR_adjusted], 0.83; P = 0.031). The median TFS among recipients of second-line chemotherapy without (n = 165; 57%) and with rituximab (n = 121; 42%) was 15.0 and 15.3 months, respectively (HR_adjusted, 0.93; P = 0.614). Of the 121 patients who received rituximab-containing chemotherapy in second-line, 89 (74%) and 32 (26%) received first-line chemotherapy without and with rituximab, respectively. Median TFS in these two treatment groups was 18.3 and 12.1 months, respectively (HR_adjusted, 1.71; P = 0.060). Collectively, in this population-based study, the effectiveness of first-line treatment with rituximab-containing chemotherapy was less pronounced in second-line treatment. The hampered effectiveness of rituximab-containing chemotherapy in second-line could not be explained by previous rituximab exposure.

Survival improvement of patients with chronic lymphocytic leukemia (CLL) in routine care 1995-2017

Seven hundred and twenty-four CLL-outpatients with a median age of 67 (35-92) were analyzed. Four hundred and twenty-seven (59%) were male, 297 (41%) female. At diagnosis 556 (77%) were in Binet stage A, 91 (13%) stage B and 36 (5%) stage C. Forty-six percent received treatment during the evaluation period. Treatment consisted of purine analogs in 38%, alkylating agents in 96%, chemoimmunotherapy with anti-CD20 monoclonal antibodies in 63%, ibrutinib in 9%, venetoclax in 1% and idelalisib in 3%. 3% received allogeneic hematopoietic stem cell transplantation. Overall survival (OS) according to Binet stage was: A 13.9 years (0.1-37.4), B 9.2 years (1.4-29.3) and C 7.9 years (0.5-19.4) respectively. Median OS from the start of therapy improved over time; 1995-2001: 5.8 years, 2002-2008: 6.1 years and 2009-2017: median not reached. Survival of patients with CLL has improved in routine care and was strongly related to active disease, disease stage, performance status and whether therapy included an anti-CD20 monoclonal antibody.

Efficacy of Ibrutinib-Based Regimen in Chronic Lymphocytic Leukemia: A Systematic Review

Ibrutinib has shown to have better efficacy than standard chemoimmunotherapy in del17 positive chronic lymphocytic leukemia (CLL) patients; however its role in del17 negative patients is less clear. We aim to evaluate the efficacy of ibrutinib-based regimens in CLL. Seven databases were searched in accordance with PRISMA statement guidelines using the following keywords: chronic lymphocytic leukemia, CLL, Bruton tyrosine kinase inhibitor, BTK inhibitor, ibrutinib, and PCI-32765. Data from only prospective clinical trials was included. In a phase 3 trial (n = 136), the overall response rate (ORR) with ibrutinib was 92% whereas 18% patients had a complete response (CR). Progression free survival (PFS) and overall survival (OS) at 2 years were 89% and 95% respectively. Phase 3 trial (n = 195) with single agent ibrutinib showed ORR of 63%. PFS at 6 months and OS at 12 months were 88% and 90% respectively. In a phase 2 trial of relapsed and/or refractory (R/R) or high risk treatment naive (TN) patients, combination of ibrutinib and rituximab (n = 104) achieved an ORR of 100% (CR 28%) as compared to ORR 98% (CR 21%) with ibrutinib monotherapy (n = 102) with no significant difference in PFS. Combination of ibrutinib and ublituximab (n = 64) had an ORR of 78% (CR 7%) in a phase 3 study. In del17p negative R/R patients, combination of bendamustine/rituximab (BR) and ibrutinib (n = 289) achieved an ORR of 83% (CR/CRi 10%) and the 18 month PFS was 79%. In a phase 2 trial treated with ibrutinib (n = 145), patients with del17p R/R disease achieved an ORR of 64% and the 24 month PFS and OS was 63% and 75% respectively. In TN del17p patients (n = 35), ORR was 97% (CR-0) and the 24 month PFS and OS were 82% and 84% respectively with single agent ibrutinib. Ibrutinib is the treatment of choice for patients with del17p mutation and has good efficacy in RR/TN patients without del17p mutation. Ibrutinib is being evaluated in combination with rituximab for del17p mutations. Future prospects include combination of ibrutinib with frontline chemotherapy and other novel agents for TN and RR del17p negative patients.

Past, Present, and Future of Rituximab-The World's First Oncology Monoclonal Antibody Therapy

Rituximab is a chimeric mouse/human monoclonal antibody (mAb) therapy with binding specificity to CD20. It was the first therapeutic antibody approved for oncology patients and was the top-selling oncology drug for nearly a decade with sales reaching $8.58 billion in 2016. Since its initial approval in 1997, it has improved outcomes in all B-cell malignancies, including diffuse large B-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukemia. Despite widespread use, most mechanistic data have been gathered from in vitro studies while the roles of the various response mechanisms in humans are still largely undetermined. Polymorphisms in Fc gamma receptor and complement protein genes have been implicated as potential predictors of differential response to rituximab, but have not yet shown sufficient influence to impact clinical decisions. Unlike most targeted therapies developed today, no known biomarkers to indicate target engagement/tumor response have been identified, aside from reduced tumor burden. The lack of companion biomarkers beyond CD20 itself has made it difficult to predict which patients will respond to any given anti-CD20 antibody. In the past decade, two new anti-CD20 antibodies have been approved: ofatumumab, which binds a distinct epitope of CD20, and obinutuzumab, a mAb derived from rituximab with modifications to the Fc portion and to its glycosylation. Both are fully humanized and have biological activity that is distinct from that of rituximab. In addition to these new anti-CD20 antibodies, another imminent change in targeted lymphoma treatment is the multitude of biosimilars that are becoming available as rituximab's patent expires. While the widespread use of rituximab itself will likely continue, its biosimilars will increase global access to the therapy. This review discusses current research into mechanisms and potential biomarkers of rituximab response, as well as its biosimilars and the newer CD20 binding mAb therapies. Increased ability to assess the effectiveness of rituximab in an individual patient, along with the availability of alternative anti-CD20 antibodies will likely lead to dramatic changes in how we use CD20 antibodies going forward.