Comparative assessment of pharmacokinetics, and pharmacodynamics between RTXM83™, a rituximab biosimilar, and rituximab in diffuse large B-cell lymphoma patients: a population PK model approach

Long-Term Safety and Effectiveness of Rituximab Biosimilar RTXM83: A Retrospective Extension Study in Brazilian Patients with Diffuse Large B-Cell Lymphoma

INTRODUCTION

RTXM83, a biosimilar of rituximab, was approved after physicochemical, functional, non-clinical, and clinical studies demonstrated their similarity; these studies included RTXM83-AC-01-11, a multicentric double-blind international prospective pivotal study. Long-term data on biosimilars can potentially elucidate their clinical robustness and facilitate their broader adoption.

METHODS

In this retrospective observational study, we analyzed a dataset from a Brazilian cohort previously randomized in the RTXM83-AC-01-11 study followed by the assessment of long-term outcomes in an observational extension phase from randomization in the RTXM83-AC-01-11 study to the last recorded evaluation. Patients with diffuse large B cell lymphoma (DLBCL) received either reference rituximab (R) or RTXM83 plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) as adjuvant treatment.

RESULTS

The median follow-up period was 77.0 months. Patients with initial DLBCL stages III and IV comprised 50% of the R-CHOP group and 40% of the biosimilar group. Five (18.5%) patients, including two RTXM83-CHOP-treated and three R-CHOP-treated individuals, experienced late adverse events (AEs) of interest. No new safety signs were established. At the final assessment, the progression-free survival (PFS) rates were 93.3% and 50.0% in the RTXM83-CHOP and R-CHOP groups, respectively. Median PFS was not achieved in the RTXM83-CHOP group, which was 40.5 months in the R-CHOP group. The overall survival (OS) rates were 100% and 66.7% in the RTXM83-CHOP and R-CHOP groups, respectively. The median OS was not reached in any group.

CONCLUSION

This study demonstrated the long-term safety and effectiveness of RTXM83 in treating DLBCL; outcomes comparable to those of the reference product and potentially improved access to treatment have been indicated. However, further research with more diverse patient groups can validate these findings and advocate the broader adoption of biosimilars in cancer care.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04928573. June 16, 2021, "retrospectively registered".

Rituximab biosimilar for the treatment of diffuse large B-cell lymphoma: a phase 3 randomized study in India

PURPOSE

Very few studies have demonstrated the rituximab biosimilarity in terms of efficacy, safety, pharmacokinetics, pharmacodynamics, and immunogenicity in patients with diffuse large B-cell lymphoma (DLBCL) in India. Therefore, we compared the efficacy, safety, pharmacokinetic, pharmacodynamic, and immunogenicity of our biosimilar rituximab with the reference rituximab (Ristova, Roche products [India] Pvt. Ltd) in patients with DLBCL in India.

METHODS

A phase 3, randomized, assessor-blind, parallel-group, two-arm study was conducted across 28 sites in India. A total of 153 newly diagnosed DLBCL patients were randomized to receive either biosimilar rituximab or reference rituximab. The study drugs were administered at a dose of 375 mg/m² by intravenous infusion every 3 weeks for six cycles. The primary end point was objective response rate (ORR) at the end of Cycle 6. Secondary end points included: pharmacokinetic, pharmacodynamics, immunogenicity, and safety assessment.

RESULTS

The ORR at the end of Cycle 6 was 82.14% in the biosimilar rituximab and 85.71% in the reference rituximab group. The risk difference (90% CIs) was - 3.57 (- 14.80, 7.66). It met the non-inferiority margin of - 20%. The pharmacokinetic and pharmacodynamic parameters were comparable between the two treatment groups. The incidence rate of immunogenicity was very low and similar in both the treatment groups. The safety profile of both the treatments was comparable with no major difference in terms of nature, frequency and severity of TEAEs.

CONCLUSION

The study demonstrated the biosimilarity between the biosimilar rituximab and the reference rituximab. Our biosimilar rituximab could add to the cost-effective treatment alternatives for patients with DLBCL in India.

Intra-articular Injection of a B Cell Depletion Antibody Enhances Local Exposure to the Joint-Draining Lymph Node in Mice with Collagen-Induced Arthritis

Changes to the number, type, and function of immune cells within the joint-draining lymphatics is a major contributor to the progression of inflammatory arthritis. In particular, there is a significant expansion in pathogenic B cells in the joint-draining lymph node (jdLN). These B cells appear to clog the lymphatic sinuses in the lymph node, inhibit lymph flow, and therefore, reduce the clearance of inflammatory fluid and cells from the joint. Taken together, there is potential to treat inflammatory arthritis more effectively, as well as reduce off-target side effects, with localized delivery of B-cell depleting therapies to the jdLNs. We recently reported that joint-draining lymphatic exposure of biologic disease-modifying anti-rheumatic drugs (DMARDs), including the B cell depletion antibody rituximab, is increased in healthy rats following intra-articular (IA) compared to subcutaneous (SC) or intravenous (IV) administration. This suggests that IA administration of B cell depleting antibodies may increase delivery to target cells in the jdLN and increase the effectiveness of B cell depletion compared to standard SC or IV administration. However, whether enhanced local delivery of DMARDs to the jdLN is also achieved after IA injection in the setting of inflammatory arthritis, where there is inflammation in the joint and jdLN B cell expansion is unknown. We, therefore, assessed the lymph node distribution, absorption and plasma pharmacokinetics, and B cell depletion at different sites after IA, SC, or IV administration of a fluorescently labeled mouse anti-CD20 B cell depleting antibody (Cy5-αCD20) in healthy mice compared to mice with collagen-induced arthritis (CIA). The absorption and plasma pharmacokinetics of Cy5-αCD20 appeared unaltered in mice with CIA whereas distribution of Cy5-αCD20 to the jdLNs was generally increased in mice with CIA, regardless of the route of administration. However, IA administration led to greater and more specific exposure to the jdLNs. Consistent with increased Cy5-αCD20 in the jdLNs of CIA compared to healthy mice, there was a greater reduction in jdLN weight and a trend toward greater jdLN B cell depletion at 24 h compared to 4 h after IA compared to SC and IV administration. Taken together, this data supports the potential to improve local efficacy of B cell depletion therapies through a jdLN-directed approach which will enable a reduction in dose and systemic toxicities.

Rituximab pharmacokinetic and pharmacokinetic-pharmacodynamic evaluation based on a study in diffuse large B-cell lymphoma: Influence of tumor size on pharmacokinetic and assessment of pharmacokinetic similarity

Dr. Reddy's Laboratories rituximab (DRL_RI; Dr. Reddy's Laboratories SA, Basel, Switzerland) is under development as a rituximab biosimilar. Study RI-01-002 (Clinical Trials Registry - India/2012/11/003129), comparing DRL_RI to the reference medicinal product (RMP) MabThera® (Roche, Grenzach-Wyhlen, Germany), demonstrated pharmacokinetic (PK) equivalence and showed comparable pharmacodynamic, efficacy, safety, and immunogenicity profiles. We used data from the same study to perform population PK and PK-pharmacodynamic analyses: first exploring possible factors influencing the PK similarity assessment between products and then performing simulations to investigate the impact of tumor size on rituximab PK. Nonlinear mixed-effects models for PK, tumor size, tumor size-PK, and tumor response were developed independently. The final PK model included drug product as a dose-scaling parameter and predicted a 6.75% higher dose reaching the system in RMP-treated patients. However, when tumor size was included in the tumor size-PK model, the drug product effect was no longer observed. The model rather indicated that patients with larger tumor size have higher clearance. Further simulations confirmed that higher baseline tumor size is associated to slightly lower rituximab exposure. Tumor response, described by a continuous-time Markov model, did not differ between drug products. Both had higher effects during the first 20 weeks of treatment. Also, the model described a subpopulation of nonresponders to treatment (42%) with faster transitions to a worse state. The different rituximab exposure initially detected between drug products (6.75%) was shown using PK/PK-pharmacodynamic analysis to be attributed to a tumor size imbalance between treatment groups. PK/PK-pharmacodynamic analyses may contribute to PK similarity assessments.

Efficacy and safety of MIL60 compared with bevacizumab in advanced or recurrent non-squamous non-small cell lung cancer: a phase 3 randomized, double-blind study

BACKGROUND

We compared the efficacy, safety, and immunogenicity of MIL60 with reference bevacizumab as first-line treatment in patients with advanced or recurrent non-squamous non-small cell lung cancer (NSCLC) in this phase 3, randomized, double-blind study.

METHODS

Patients with untreated advanced or recurrent NSCLC were randomized (1:1 ratio) to receive either MIL60 or bevacizumab in combination with paclitaxel/carboplatin. Patients with non-progressive disease continued maintenance single-agent MIL60 until disease progression, or intolerable toxicity. The primary endpoint was the 12-week objective response rates (ORR12) by independent review committee (IRC) using RECIST 1.1. Bioequivalence was established if the ORR ratio located between 0.75 and 1/0.75. The trial was registered with clinicaltrials.gov (NCT03196986).

FINDINGS

Between Aug 23, 2017, and May 8, 2019, 517 patients were randomly assigned to MIL60 group (n=257) and bevacizumab group (n=260). In the full analysis set (FAS) population including all randomized and evaluable patients who received at least one dose of MIL60 or bevacizumab, the ORR12 in MIL60 group and bevacizumab group were 48.6% and 43.1%, respectively. The ORR ratio of these two groups were 1.14 (90% CI 0.97-1.33), which fell within the pre-specified equivalence boundaries (0.75-1/0.75). The median DOR was 5.7 months (95% CI 4.5-6.2) for MIL60 and 5.6 months (95% CI 4.3-6.4) for bevacizumab. No significant difference was noted in median PFS (7.2 vs. 8.1 months; HR 1.01, 95% CI 0.78-1.30, p=0.9606) and OS (19.3 vs. 16.3 months; HR 0.81, 95% CI 0.64-1.02, p=0.0755). Safety and tolerability profiles were similar between the two groups. No patient detected positive for Anti-drug antibody (ADA).

INTERPRETATION

The efficacy, safety and immunogenicity of MIL60 were similar with bevacizumab, providing an alternative treatment option for advanced or recurrent non-squamous NSCLC.

FUNDING

This study was sponsored by Betta Pharmaceutical Co., Ltd.

The Influence of Underlying Disease on Rituximab Pharmacokinetics May be Explained by Target-Mediated Drug Disposition

BACKGROUND AND OBJECTIVES

Rituximab is an anti-CD20 monoclonal antibody approved in several diseases, including chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), rheumatoid arthritis (RA), and anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). The influence of underlying disease on rituximab pharmacokinetics has never been investigated for several cancer and non-cancer diseases simultaneously. This study aimed at assessing this influence using an integrated semi-mechanistic model accounting for target-mediated elimination of rituximab.

METHODS

Rituximab concentration-time data from five studies previously published in patients with CLL, DLBCL, FL, RA, and AAV were described using a two-compartment model with irreversible binding of rituximab to its target antigen. Both underlying disease and target antigen measurements were assessed as covariates.

RESULTS

Central volume of distribution was [95% confidence interval] 1.7-fold [1.6-1.9] higher in DLBCL than in RA, FL, and CLL, and it was 1.8-fold [1.6-2.1] higher in RA, FL, and CLL than in AAV. First-order elimination rate constants were 1.8-fold [1.7-2.0] and 1.3-fold [1.2-1.5] higher in RA, DLBCL, and FL than in CLL and AAV, respectively. Baseline latent antigen level (L₀) was 54-fold [30-94], 20-fold [11-36], and 29-fold [14-64] higher in CLL, DLBCL, and FL, respectively, than in RA and AAV. In lymphoma, L₀ increased with baseline total metabolic tumor volume (p = 6.10^-7). In CLL, the second-order target-mediated elimination rate constant (k_deg) increased with baseline CD20 count on circulating B cells (CD20_cir, p = 0.0081).

CONCLUSIONS

Our results show for the first time that rituximab pharmacokinetics is strongly influenced by underlying disease and disease activity. Notably, neoplasms are associated with higher antigen amounts that result in decreased exposure to rituximab compared to inflammatory diseases. Our model might be used to estimate unbound target amounts in upcoming studies.

Rituximab exposure-response in triweekly R-CHOP treatment in DLBCL: A loading dose is recommended to improve clinical outcomes

Previous exposure-response analyses for rituximab suggest that higher rituximab concentrations were associated with an improvement in efficacy, however, clinical studies investigating a higher rituximab dose had mixed results. To further explore the exposure-response relationship of rituximab, a prospective observational analysis was performed involving 121 newly diagnosed patients with diffuse large B-cell lymphoma treated with triweekly rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). The trough concentration in the first cycle (C_1-trough ) was significantly higher in patients achieving complete response (CR) compared with patients that did not achieve CR (22.00 μg/ml vs. 16.62 μg/ml, p = 0.0016), however, this difference between the two groups disappeared in later cycles. The relationship between rituximab C_1-trough and achieving a CR was confirmed by matched-pair logistic regression analysis (odds ratio, 0.79; p = 0.0020). In addition, a higher C_1-trough (≥18.40 μg/ml) was associated with longer progression-free survival (p < 0.0001) and overall survival (p = 0.0038). The percentages of patients that did not achieve a CR and had recurrence after CR within 24 months were 35% and 22.50%, respectively, for patients with a C_1-trough less than or equal to 18.40 μg/ml, compared with 12.35% and 6.17% for patients with C_1-trough greater than 18.40 μg/ml. Disease stage was found to be the most significant influencing factor of C_1-trough , with 51.02% of patients at stage IV with an observed C_1-trough less than 18.40 μg/ml. For these advanced patients, population pharmacokinetic simulations using an established model suggest that a loading dose of 800 mg/m²  may help to improve clinical outcomes.

Population Pharmacokinetics of Rituximab in Pediatric Patients With Frequent-Relapsing or Steroid-Dependent Nephrotic Syndrome

Objectives: Rituximab is frequently used off-label for the treatment of frequent-relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS), but the relapse rate remained high and the dosing regimen varied widely. The objective of this study was to characterize rituximab pharmacokinetics (PK) in pediatric patients with FRNS/SDNS, and to investigate the differences in rituximab PK between patients with FRNS/SDNS and other disease populations.

Methods: Fourteen pediatric patients received rituximab for FRNS/SDNS treatment were enrolled in a prospective, open-label, single-center PK study. A population PK model of rituximab was developed and validated, and PK parameters were derived for quantitative evaluation.

Results: A two-compartment PK model best described the data. Body surface area was the most significant covariate for both central clearance (CL) and apparent central volume of distribution (V₁). Patients with FRNS/SDNS exhibited a clinically relevant increase in rituximab CL compared to patient population with non-Hodgkin’s lymphoma (NHL).

Conclusion: This pilot study indicated that higher doses or more frequent regimens of rituximab may be required for optimal therapeutic effects in patients with FRNS/SDNS. Further clinical studies with more patients are warranted to confirm this result.

Non-Linear Rituximab Pharmacokinetics and Complex Relationship between Rituximab Concentrations and Anti-Neutrophil Cytoplasmic Antibodies (ANCA) in ANCA-Associated Vasculitis: The RAVE Trial Revisited

BACKGROUND AND OBJECTIVES

Rituximab is approved in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and leads to a decrease of ANCA levels. The objectives of this study were to investigate the non-linear pharmacokinetics of rituximab and the relationship between its concentrations and ANCA levels in AAV patients.

METHODS

Ninety-two AAV patients from the RAVE (Rituximab in ANCA-Associated Vasculitis) trial were assessed. Both ANCA anti-myeloperoxidase (MPO-ANCA) and anti-proteinase 3 (PR3-ANCA) levels were used as biomarkers. The pharmacokinetics of rituximab were described using a semi-mechanistic two-compartment model that included a latent target antigen turnover and allowed the estimation of specific target-mediated elimination in addition to its non-specific elimination of rituximab. The effect of rituximab on the ANCA level was described using a semi-mechanistic compartment model with a negative feedback (Friberg) model with no transit compartment. A population modeling approach was used.

RESULTS

Our pharmacokinetic and pharmacokinetic-pharmacodynamic (PK-PD) models satisfactorily described both concentration-time and concentration-effect relationship data. The mean (inter-individual standard deviation) estimated non-specific clearance was 0.15 L/day (0.30%) and the target-mediated elimination rate constant was 2.4 × 10^-5 nmol/day. The elimination half-lives for MPO-ANCA and PR3-ANCA were 24 and 18 days, respectively.

CONCLUSIONS

A non-linear target-mediated elimination of rituximab was detected in AAV patients. Our PK-PD model allowed quantification of the association between rituximab concentrations and ANCA levels. This decrease was deep but delayed, and more sustained in patients with MPO-ANCA than in those with PR3-ANCA. Our results suggest that repeating courses of rituximab might improve the clinical response to rituximab.

Current state and comparison of the clinical development of bevacizumab, rituximab and trastuzumab biosimilars

Monoclonal antibodies are highly complex, large and biologic products with a substantial impact on the clinical management of a variety of diseases including cancer. The expiry of patents for essential monoclonal antibodies in cancer care such as bevacizumab, rituximab and trastuzumab, has prompted the global development of biosimilars to balance the biologics market. However, an understanding of the different approach of biosimilar development compared with its reference medicinal product, especially in the context of clinical trial design and end point selection may help oncologists integrating biosimilars into clinical practice. Herein, we reviewed the clinical development of biosimilars in oncology comparing the available clinical data of proposed biosimilars of bevacizumab, rituximab and trastuzumab.

Low initial trough concentration of rituximab is associated with unsatisfactory response of first-line R-CHOP treatment in patients with follicular lymphoma with grade 1/2

For follicular lymphoma (FL) with grade 1/2, the complete response (CR) rate of the first-line R-CHOP treatment was significantly low. In this study, we assessed the rationality of the administration of rituximab for FL patients with grade 1/2 based on concentration-response relationship analyses. Thus, we conducted a prospective pharmacokinetic (PK) study in 68 FL patients with grades 1-3 treated with R-CHOP at 21-day intervals. Plasma rituximab concentrations were quantified using ELISA and the population PK modeling was established with Phoenix^® NLME^TM. The first cycle trough concentration (C_1-trough) of rituximab was a significant independent risk factor for achieving CR in matched-pair logistic regression analysis, rather than the concentrations in later cycles; the recommendatory minimum optimal C_1-trough was 13.60 μg/mL. Patients with grade 1/2 had significantly lower C_1-trough compared with grade 3 (12.21 μg/mL vs. 23.45 μg/mL, P < 0.001), only 30% patients with grade 1/2 could reach 13.60 μg/mL, compared with 91.67% in patients with grade 3, which was in accord with its unsatisfactory CR rates (43.33% vs. 76.32%). The stage indicating the tumor burden (the target) was a crucial influence factor for C_1-trough, accounting for 40.70% of its variability, 70% patients with grade 1/2 were stage IV in this study, since the systemic therapy only started at the disseminated disease stage. The initial dose of 1800 mg was recommended by Monte Carlo simulation for patients with grade 1/2. In summary, low C_1-trough accounted for low-grade FL's unsatisfactory CR rate, designing the first dosage of rituximab should be a very important component of individualized therapy for FL.

Efficacy and safety of biosimilar rituximab (ZytuxTM) in newly diagnosed patients with non-Hodgkin lymphoma and chronic lymphocytic leukemia

Chronic Lymphocytic Leukemia (CLL) and Non-Hodgkin Lymphoma (NHL) are considered parts of mature B cell neoplasms in WHO classification. They are both characterized by accumulation of B cells in blood, lymphoid tissues and bone marrow. Most of treatment protocols of NHL and CLL contain rituximab in addition to chemotherapy, which has been associated with improved survival. The aim of this study was to assess the efficacy and safety of Zytux™ (AryoGen Pharmed) in newly diagnosed patients with NHL and CLL. A prospective single center study conducted at the National Center of Hematology, Mustansiriyah University, from January 2018 till October 2018. Twenty patients were included in this study, ten of them were NHL and ten patients were CLL. All patients were treated with Zytux™ in addition to designated protocol. All patient were followed up for 6 months and evaluated at the end of each protocol. There were 20 patients in this study; the overall median age for all patients in this study was 66 years. The median age was 57.5 years for NHL and 68.5 years for CLL. There were 13 males and 7 females in total, with male predominance in both groups. Regarding safety profile, Zytux™ demonstrated similar adverse reactions in comparison to MabThera® (Roche Spa). Moreover, the overall response rate in both groups was 85% with complete response achieved in 35% and partial response in remaining 50%.This study concluded that the early results of use of Zytux™ in NHL and CLL were not inferior to reference drug MabThera® in contrast it was comparable and even better in term of safety and efficacy.

Comparison of Utilization Trends between Biosimilars and Generics: Lessons from the Nationwide Claims Data in South Korea

BACKGROUND

South Korea is unique in that it leads global markets in R&D as well as production of biosimilar products and was the first market into which some biosimilar products were introduced. We analyzed the time trend of market penetration and simulated saved spending by biosimilars in South Korea.

METHODS

We pulled Korean National Health Insurance claims data from January 2012-December 2018 for second-generation biologics, including infliximab, rituximab, and trastuzumab, and examined the time trends of expenditure, utilization in defined daily dose, and price. We also assessed market penetration by biosimilars and simulated expenditure savings gained due to their introduction. We comparatively examined time trends and spending savings during the same period for selected small-molecule generic drugs to understand any specifics limited to biosimilars for time trends of market share and quantity-standardized prices.

RESULTS

The market share for infliximab biosimilar plateaued at over 30%, which is smaller than the market penetration of esomeprazole (over 60%), a small-molecule comparator. Despite a shorter observation period, rituximab and trastuzumab biosimilars also showed larger utilization rates (12.89% and 13.93%, respectively) than infliximab (9.05%) in their second year after market entry. Infliximab was associated with approximately US $82-114 million expenditure savings over 6 years after its biosimilar entry to the market. Rituximab and trastuzumab biosimilars each also resulted in reduction in total spending by approximately US $9-14 million, in less than 2 years.

CONCLUSION

Biosimilars captured the market rapidly, despite a heterogeneous uptake rate by product in South Korea. However, expansion of biosimilar use in the market and consequent expenditure savings need to be supported by pre-emptive policy measures to encourage price competition and boost utilization.

The Influence of Different Disease States on Rituximab Pharmacokinetics

BACKGROUND

The anti-CD20 antibody rituximab, which promotes the selective depletion of CD20 positive B cells, was the first targeted therapy that was approved for the treatment of B-cell malignancies, and it is now widely prescribed in both malignant and non-malignant, immune-related diseases. However, the cause of its various clinical responses in certain diseases, have not been clearly elucidated. The variabilities in inter-individual pharmacokinetic and the emerging evidence of the relationships between pharmacokinetic and pharmacodynamic may provide a better understanding of this drug.

METHODS

We searched and summarized the latest published articles on rituximab pharmacokinetic profiles and the pharmacokinetic/pharmacodynamic models in different patient populations, including B-cell malignancies, rheumatoid arthritis, ANCA-associated vasculitis, and glomerular kidney diseases.

RESULTS

Most pharmacokinetic data are drawn from clinical studies in oncology clinical practice. Body weight, gender, and antigen-related factors are proven to be the key factors affecting rituximab pharmacokinetics. In addition, the positive exposure-response relations were reported, which provide encouraging evidence for individualized therapies. While in immune disorders, especially in the off-labeled indications, pharmacokinetic studies are quite limited. Compared with that in B-cell malignancies, the differences in the pharmacokinetic parameters may be attributed to the different pathogeneses of diseases, mechanisms of action and dosing strategies. However, the correlation between drug exposure and clinical outcomes remains unclear.

CONCLUSION

Here, we provide an overview of the complexities associated with rituximab pharmacokinetics and pharmacodynamics in different diseases. Although many influencing factors need to be verified in future studies, a better understanding of the relationships between pharmacokinetic and pharmacodynamic may assist in optimizing rituximab clinical practice.

Pharmacokinetics and safety of IBI301 versus rituximab in patients with CD20+ B-cell lymphoma: a multicenter, randomized, double-blind, parallel-controlled study

This multicenter, randomized, double-blind, parallel-controlled trial aimed to compare the pharmacokinetics (PK) of IBI301 with rituximab in patients with CD20-positive (CD20⁺) B-cell lymphoma, who achieved a complete response/unconfirmed complete response after standard treatments. Patients were randomized (1:1) to receive IBI301 or rituximab (375 mg/m², IV). Patients who continuously benefitted from the trial after the PK phase underwent the extension phase to receive up to three cycles of 3-month-cycle of rituximab/IBI301 maintenance therapy. PK was described using the area under the serum concentration–time curve from time zero to infinity (AUC_0-inf), AUC from time zero to last quantifiable concentration (AUC_0-t), and maximum serum concentration (C_max). Pharmacodynamics (PD), incidence of adverse events and immunogenicity were evaluated. PK was defined equivalent, if 90% confidence intervals (CIs) for geometric mean ratios of PK endpoints fell within the margin of 0.8–1.25. Overall, 181 patients were enrolled in IBI301 (n = 89) and rituximab (n = 92) groups. Geometric mean ratios of AUC_0-inf, AUC_0-t, and C_max were 0.91 (90% CI 0.85, 0.97), 0.91 (90% CI 0.86, 0.97), and 0.96 (90% CI 0.92, 1.01) between treatment groups, all within the bioequivalence range. Peripheral CD19⁺ and CD20⁺ B-cell counts were similar at each prespecified time point between the groups. No difference in immunogenicity was observed. The incidences of treatment-emergent adverse events (84.3% vs. 83.5%) and treatment-related AEs (56.2% vs. 61.5%) were comparable (IBI301 vs. rituximab). IBI301 was PK bioequivalent to rituximab in patients with CD20⁺ B-cell lymphoma. The PD, safety, and immunogenicity profiles of IBI301 were similar to those of rituximab.

Randomized, Double-Blind, Pharmacokinetic Equivalence Trial Comparing DRL-Rituximab With MabThera in Patients With Diffuse Large B-Cell Lymphoma

PURPOSE

We sought to compare the pharmacokinetics (PKs) of DRL-rituximab (DRL_RI; potential biosimilar) and innovator rituximab MabThera (Roche, Grenzach-Wyhlen, Germany; reference medicinal product [RMP]) in patients with diffuse large B-cell lymphoma (DLBCL). Efficacy, pharmacodynamics (PDs), safety, and immunogenicity were also compared.

PATIENTS AND METHODS

We conducted a double-blind, parallel-group study in patients with untreated DLBCL who were eligible to receive cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) therapy. Patients were randomly assigned at a one-to-one ratio to receive DRL_RI or RMP for six 21-day cycles of rituximab plus CHOP, with 18 months of follow-up after day 1, cycle 6 (C6). Primary end point was C1 PKs, measured as area under the plasma concentration–time curve from day 0 to 21 (AUC_{0-21 days}) and maximum plasma concentration (C_max). Equivalence was defined as 90% CIs for the DRL_RI/RMP geometric mean ratios (GMRs) within 80% and 125%. Secondary end points included efficacy noninferiority measured by objective response rate (ORR) at C6 and event-free survival and overall survival at 87 weeks, PK equivalence at C6 and PD equivalence (rate of B-cell depletion and repletion), safety, and immunogenicity. The trial was stopped after sufficient patients for primary end point evaluation were enrolled. Secondary end points are reported as observed.

RESULTS

A total of 151 patients were randomly assigned (DRL_RI, n = 76; RMP, n = 75). DRL_RI/RMP GMRs for AUC_{0-21 days} and C_max in C1 were 99.77 (90% CI, 87.60 to 113.63) and 96.19 (90% CI, 88.65 to 104.38), respectively. ORR at C6 for DRL_RI and RMP were 82.0% and 84.8%, respectively. Rates of B-cell depletion/repletion, immunogenicity, and adverse events were comparable in both groups.

CONCLUSION

DRL_RI and RMP had equivalent PKs, with comparable efficacy, PDs, safety, and immunogenicity.

Toxicology and Pharmacokinetic Studies in Mice and Nonhuman Primates of the Nontoxic, Efficient, Targeted Hexameric FasL: CTLA4-FasL

Cytotoxic T-lymphocyte antigen 4 (CTLA4)-FasL, a homo-hexameric signal converter protein, is capable of inducing robust apoptosis in malignant cells of the B-cell lineage expressing its cognate B7 and Fas targets, while sparing nonmalignant ones. This fusion protein's striking proapoptotic efficacy stems from its complementary abilities to coordinately activate apoptotic signals and abrogate antiapoptotic ones. A limiting factor in translating FasL or Fas receptor agonists into the clinic has been lethal hepatotoxicity. Here, we establish CTLA4-FasL's in vivo efficacy in multiple murine and xenograft models, for both systemic and subcutaneous tumors. Significantly, good laboratory practice (GLP) toxicology studies in mice indicate that CTLA4-FasL given repeatedly at doses up to five times the effective dose was well-tolerated and resulted in no significant adverse events. An equivalent single dose of CTLA4-FasL administered to nonhuman primates was also well-tolerated, albeit with a moderate dose-dependent leukopenia that was completely reversible. Interestingly, monkey peripheral blood mononuclear cells were more sensitive to CTLA4-FasL-induced apoptosis when tested in vitro. In both species, there was short-term elevation in serum levels of IL6, IL2, and IFNγ, although this was not associated with clinical signs of proinflammatory cytokine release, and further, this cytokine elevation could be completely prevented by dexamethasone premedication. Liver toxicity was not observed in either species, as confirmed by serum liver enzyme levels and histopathologic assessment. In conclusion, CTLA4-FasL emerges from animal model studies as an effective and safe agent for targeted FasL-mediated treatment of B7-expressing aggressive B-cell lymphomas.

Population pharmacokinetic modeling of PF-06439535 (a bevacizumab biosimilar) and reference bevacizumab (Avastin®) in patients with advanced non-squamous non-small cell lung cancer

Purpose

The objectives of this analysis were to characterize the population pharmacokinetics (PK) of PF-06439535 (a bevacizumab biosimilar) and reference bevacizumab (Avastin^®) sourced from the European Union (bevacizumab-EU) in patients with advanced non-squamous non-small cell lung cancer (NSCLC), and to quantify the difference in PK parameters between the two drug products via covariate analysis.

Methods

Pooled PF-06439535 and bevacizumab-EU serum concentration data from a comparative clinical efficacy and safety study (NCT02364999) in patients with NSCLC (N = 719) were analyzed using a non-linear mixed-effects modeling approach. Patients received PF-06439535 plus chemotherapy or bevacizumab-EU plus chemotherapy every 21 days for 4–6 cycles, followed by monotherapy with PF-06439535 or bevacizumab-EU. PF-06439535 or bevacizumab-EU was administered intravenously at a dose of 15 mg/kg. Effects of patient and disease covariates, as well as the drug product (PF-06439535 versus bevacizumab-EU), on PK were investigated.

Results

Overall, 8632 serum bevacizumab concentrations from 351 patients in the PF-06439535 group and 354 patients in the bevacizumab-EU group were included in the analysis. A two-compartment model adequately described the combined data. Clearance (CL) and central volume of distribution (V₁) estimates were 0.0113 L/h and 2.99 L for a typical 71-kg female patient with NSCLC administered bevacizumab-EU. CL and V₁ increased with body weight and were higher in males than females even after accounting for differences in body weight. The 95% confidence intervals for the effect of drug product on CL and V₁ encompassed unity.

Conclusions

The population PK of PF-06439535 and bevacizumab-EU were well characterized by a two-compartment model. Covariate analysis did not reveal any appreciable differences between PK parameters for PF-06439535 and bevacizumab-EU in patients with NSCLC.

Clinical trial registration

ClinicalTrials.gov, NCT02364999.

Electronic supplementary material

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Pharmacist perspectives and considerations for implementation of therapeutic oncology biosimilars in practice

Purpose

An overview of therapeutic oncology biosimilars, the U.S. biosimilars regulatory pathway, and the clinical development of selected biosimilar products is provided, including discussion of considerations in adopting biosimilars into oncology practice.

Summary

Biosimilars are biologic agents that are highly similar to and have no clinically meaningful differences from an approved reference product in terms of safety, purity, and potency. There is a large market for cancer biologics, and approval of biosimilars has the potential to increase access to care and reduce costs. An abbreviated regulatory pathway for the development and approval of biosimilars defines a stepwise approach to demonstrating biosimilarity and conducting clinical comparative trials to confirm equivalent pharmacokinetics, efficacy, safety, and immunogenicity to the reference product. Three therapeutic biologics (bevacizumab, trastuzumab, and rituximab) have been used extensively in the treatment of a variety of cancers and are targets for biosimilar product development. Preclinical and clinical experience with 2 recently approved biosimilars to bevacizumab and trastuzumab is reviewed. Challenges faced by pharmacy and therapeutics committees when considering oncology biosimilars for formulary inclusion are discussed.

Conclusion

Increased adoption of biosimilars could potentially lower treatment costs and improve access to biologics for patients with cancer. Key considerations in formulary review of biosimilars include the quality and quantity of data from comparative clinical trials, economic factors, manufacturer reliability, and challenges associated with incorporating biosimilars into practice.

Sensitivity of Pegfilgrastim Pharmacokinetic and Pharmacodynamic Parameters to Product Differences in Similarity Studies

In this work, a previously developed pegfilgrastim (PG) population pharmacokinetic-pharmacodynamic (PKPD) model was used to evaluate potential factors of importance in the assessment of PG PK and PD similarity. Absolute neutrophil count (ANC) was the modelled PD variable. A two-way cross-over study was simulated where a reference PG and a potentially biosimilar test product were administered to healthy volunteers. Differences in delivered dose amounts or potency between the products were simulated. A different baseline absolute neutrophil count (ANC) was also considered. Additionally, the power to conclude PK or PD similarity based on areas under the PG concentration-time curve (AUC) and ANC-time curve (AUEC) were calculated. Delivered dose differences between the products led to a greater than dose proportional differences in AUC but not in AUEC, respectively. A 10% dose difference from a 6 mg dose resulted in 51% and 7% differences in AUC and AUEC, respectively. These differences were more pronounced with low baseline ANC. Potency differences up to 50% were not associated with large differences in either AUCs or AUECs. The power to conclude PK similarity was affected by the simulated dose difference; with a 4% dose difference from 6 mg the power was approximately 29% with 250 subjects. The power to conclude PD similarity was high for all delivered dose differences and sample sizes.

Rituximab biosimilar RTXM83 versus reference rituximab in combination with CHOP as first-line treatment for diffuse large B-cell lymphoma: a randomized, double-blind study

This multicenter, double-blind, randomized study compared the efficacy, pharmacokinetics (PKs)/pharmacodynamics (PDs), safety and immunogenicity profile of RTXM83 vs. reference rituximab (R-rituximab), both with CHOP, as first-line treatment of diffuse large B-cell lymphoma (DLBCL). A total of 272 patients <65 years of age, with good prognosis (136 per arm) were randomized (1:1) to receive six cycles of either RTXM83 or R-rituximab. The primary efficacy endpoint was achieved (overall response rate of 83.6% for RTXM83 and 82.9% for R-rituximab) with a difference 0.7% between arms (95%CI: [-8.77% to 10.17%]) fulfilling the predefined non-inferiority margin (-13%). Similar number of patients reported at least one adverse event (AE) (131 per arm) or one serious AE (47 with RTXM83 and 45 with R-rituximab). Anti-drug antibody development was comparable between the arms. PK/PD secondary endpoint results support similarity between the compounds. RTXM83 exhibits non-inferior efficacy and similar safety/immunogenicity to R-rituximab, being an accessible alternative for the treatment of patients with previously untreated DLBCL.

Nonlinear pharmacokinetics of rituximab in non-Hodgkin lymphomas: A pilot study

AIMS

Rituximab is an anti-CD20 monoclonal antibody approved in non-Hodgkin lymphoma (NHL). This study aimed to assess the relationship between antigen mass and nonlinear pharmacokinetics of rituximab in NHL patients.

METHODS

In a retrospective cohort of 25 NHL patients treated with rituximab, antigen mass was assessed at baseline by measuring metabolic tumour volume (MTV) by positron emission tomography. Rituximab pharmacokinetics was described using a semimechanistic 2-compartment model including a latent target antigen. Rituximab target-mediated elimination was described as irreversible binding between rituximab and it target. Histology (follicular or diffuse large B-cell lymphomas), initial MTV and body weight were tested as covariates on pharmacokinetic parameters.

RESULTS

The model allowed a satisfactory description of rituximab serum concentrations. Target-mediated elimination was maximum at the beginning of treatment and became negligible towards the end of follow-up. The second-order elimination of rituximab due to target binding and complex elimination increased with baseline MTV. Central volume of distribution increased with body weight (P = .022) and baseline MTV (P = .005).

CONCLUSIONS

This study quantified for the first time the target-mediated elimination of rituximab in NHL patients and confirmed rituximab retention by antigen mass.

Rituximab Exhibits Altered Pharmacokinetics in Patients With Membranous Nephropathy

BACKGROUND

Rituximab (RTX) is a chimeric monoclonal anti-CD20 antibody used off-label in the treatment of membranous nephropathy (MN). Unfortunately, limited information is available on the pharmacokinetics of therapeutic proteins such as RTX in patients with glomerular kidney diseases.

OBJECTIVE

The current study evaluated RTX pharmacokinetics in patients with MN (n = 20) who received 4 RTX weekly intravenous infusions (375 mg/m²) over a month, with a repeat of the identical treatment at 6 months. Baseline patient characteristics were gender (17 male/3 female), age (49 ± 13 years), and body surface area (2.2 ± 0.24 m²).

METHODS

Compartmental pharmacokinetic analyses were conducted using Phoenix, and comparisons of these parameters were made between the MN patients and published data from 2 reference populations without kidney diseases (follicular lymphoma and autoimmune disorders).

RESULTS

Patients with MN exhibited a shorter half-life, reduced volume of central compartment, decreased area under the serum concentration-time curve (exposure), and increased RTX clearance from the central compartment versus previous reports in the reference patient populations.

CONCLUSIONS AND RELEVANCE

These results suggest that shorter half-life and lower exposures to RTX in patients with MN may necessitate higher doses and/or changes to dosing frequency to optimize the relationships between serum concentrations and therapeutic effects.

Biosimilar medicines used for cancer therapy in Europe: a review

This article provides an updated review of the biosimilar medicines approved for cancer therapy in the European Union (EU). First we discuss the most relevant aspects for the development and approval of biosimilar medicines. We then present the oncological biosimilar drugs currently used, which include epoetins (alpha and zeta), filgrastim, and monoclonal antibodies (rituximab, trastuzumab and bevacizumab). Among the clinical applications of biosimilar medicines, cancer therapy remains the main target area and more approved biosimilars are expected over the next few years, providing cost-effective drugs to more patients. Furthermore, comprehensive pharmacovigilance studies are going on, monitoring the marketed biosimilars, and providing more feasible information to clinicians regarding the safety and efficacy of these medications.

Biosimilars in oncology and inflammatory diseases: current and future considerations for clinicians in Latin America

Biological therapies have revolutionized the treatment of several cancers and systemic immune-mediated inflammatory conditions. Expiry of patents protecting a number of biologics has provided the opportunity to commercialize highly similar versions, known as biosimilars. Biosimilars are approved by regulatory agencies via an independent pathway that requires extensive head-to-head comparison with the originator product. Biosimilars have the potential to provide savings to healthcare systems and expand patient access to biologics. In Latin American countries, regulatory frameworks for biosimilar approval have been introduced in recent years, and biosimilars of monoclonal antibody and fusion protein therapies are now emerging. However, the situation in this region is complicated by the presence of "non-comparable biotherapeutics" (also known as "intended copies"), which have not been rigorously compared with the originator product. We review the considerations for clinicians in Latin American countries, focusing on monoclonal antibody biosimilars relevant to oncology, rheumatology, gastroenterology, and dermatology.