Progression-free survival shortens after each relapse in patients with follicular lymphoma treated in the rituximab era

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.

Combination lenalidomide-rituximab immunotherapy activates anti-tumour immunity and induces tumour cell death by complementary mechanisms of action in follicular lymphoma

Chemotherapy plus rituximab has been the mainstay of treatment for follicular lymphoma (FL) for two decades but is associated with immunosuppression and relapse. In phase 2 studies, lenalidomide combined with rituximab (R²) has shown clinical synergy in front‐line and relapsed/refractory FL. Here, we show that lenalidomide reactivated dysfunctional T and Natural Killer (NK) cells ex vivo from FL patients by enhancing proliferative capacity and T‐helper cell type 1 (Th1) cytokine release. In combination with rituximab, lenalidomide improved antibody‐dependent cellular cytotoxicity in sensitive and chemo‐resistant FL cells, via a cereblon‐dependent mechanism. While single‐agent lenalidomide and rituximab increased formation of lytic NK cell immunological synapses with primary FL tumour cells, the combination was superior and correlated with enhanced cytotoxicity. Immunophenotyping of FL patient samples from a phase 3 trial revealed that R² treatment increased circulating T‐ and NK‐cell counts, while R‐chemotherapy was associated with reduced cell numbers. Finally, using an in vitro model of myeloid differentiation, we demonstrated that lenalidomide caused a reversible arrest in neutrophil maturation that was distinct from a cytotoxic chemotherapeutic agent, which may help explain the lower rates of neutropenia observed with R²versus R‐chemotherapy. Taken together, we believe these data support a paradigm shift in the treatment of FL – moving from combination immunochemotherapy to chemotherapy‐free immunotherapy.

Novel treatment approaches and future perspectives in follicular lymphoma

Follicular lymphoma (FL) is a common B-cell malignancy characterized by relatively indolent growth and incurability with an expected lifetime course of serial intermittent treatment courses. Many patients with FL have lives shortened by the disease and despite a relatively favorable prognosis relative to other incurable systemic malignancies, optimal management of FL has not been achieved. This review focuses on identifying both patients for whom novel therapies might be most beneficial as well as systematically reviewing novel strategies at various levels of investigation. Prognostic markers incorporating clinical measurements and tumor genetics are discussed, yet at the time of diagnosis do not yet powerfully discriminate patients for whom specific strategies are beneficial. Reassessment of prognosis after evaluating the response to initial therapy is the most powerful identifier of those in need of novel management strategies. For initial therapy of high burden systemic disease, anti-CD20 antibody along with chemotherapy or immunomodulators all offer relatively similar effects on overall survival with subtly different effects on progression-free survival and quality of life. Several new agents currently under investigation in the upfront setting are discussed. Perhaps the best testing ground for novel therapies is in patients with early relapse following initial immunochemotherapy. Ongoing research in multiple therapy classes including, novel monoclonal antibodies, antibody drug conjugates, immunomodulatory agents, intracellular pathway inhibitors, immune checkpoint inhibitors, and epigenetic regulators are discussed herein.

Cost-Effectiveness of Obinutuzumab in Combination with Bendamustine Followed by Obinutuzumab Maintenance versus Bendamustine Alone in Treatment of Patients with Rituximab-Refractory Follicular Lymphoma in Norway

AIMS

To evaluate the cost-effectiveness of obinutuzumab in combination with bendamustine followed by obinituzumab maintenance (Obin-Benda) compared to bendamustine alone (Benda) in patients with refractory follicular lymphoma (FL) in a Norwegian setting.

METHODS

A three-state area-under-the-curve (AUC) model was developed. The states included were progression-free-survival (PFS), progressed disease (PD), and death. Each state had costs and utilities assigned to it. The pivotal phase III randomized controlled trial GADOLIN was used for clinical input in the model along with Norwegian cost estimates. The trial demonstrated that Obin-Benda improved overall survival (OS), with a hazard ratio (HR) of 0.67 (95% CI 0.47-0.96), and reduced the likelihood of progression or death (HR 0.52, 95% CI 0.39-0.69) compared to Benda. The model used EQ-5D data collected in the GADOLIN trial, with UK tariffs assigned to the EQ-5D scores.

RESULTS

The total quality adjusted life-years (QALYs) for the patients on Obin-Benda were estimated to be 4.67, compared to 3.65 for Benda, while the total costs were estimated to be €98,849 and €51,570, respectively. Obin-Benda had an incremental gain of 1.02 QALYs compared to Benda, at an additional cost of €47,279. The estimated deterministic incremental cost-effectiveness ratio (ICER) was €46,438 per QALY gained, while the probabilistic ICER was €46,887 per QALY gained (95% CI €34,772-€59,443). The results were robust to changes in various sensitivity and scenario analyses.

CONCLUSIONS

The cost-effectiveness threshold in Norway is not public, but based on previous decisions it is estimated to be up to approximately €89,000 per QALY (NOK 800,000). The results of the analysis indicate that obinutuzumab in combination with bendamustine followed by obinutuzumab maintenance may be cost-effective compared to bendamustine alone in Norway.