Development of a subcutaneous formulation for trastuzumab - nonclinical and clinical bridging approach to the approved intravenous dosing regimen

An industry perspective on hyaluronidase co-formulated biopharmaceutics

To deliver biopharmaceutics, subcutaneous (SC) route surpasses intravenous (IV) route unequivocally in time and cost savings, but it has been limited by the injection volume of no greater than 2 mL for a long time. Recently, the adoption of hyaluronidase has become a plausible method to realize high-dose high-volume biopharmaceutical products for SC injection. Among the hyaluronidase family, the recombinant human PH20 appears to be the most reliable candidate with excellent efficacy and safety for co-formulation development. As of 2024, a total of eight hyaluronidase co-formulated biological products have been approved by regulatory authorities. This review article systematically summarized the commercial hyaluronidase co-formulated biopharmaceutics and highlighted the critical aspects of the development of future products regarding selection of hyaluronidase, formulation and process development, non-clinical evaluation, and clinical investigation. Of note, considering the uniqueness of each therapeutic agent, early and effective communication with regulatory authorities is of vital importance to successful development. Discussions were further Expanded to cover the combination of hyaluronidase co-formulations with large-volume handheld autoinjectors. The ultimate goal of this review is to provide a practical and comprehensive reference that will substantially contribute to the development of hyaluronidase co-formulated biopharmaceuticals, thereby advancing the field and benefiting patients worldwide.

Opportunities and challenges for use of minipigs in nonclinical pharmaceutical development: Results of a follow-up IQ DruSafe survey

Minipigs are valid nonrodent species infrequently utilized for pharmaceutical research and development (R&D) compared with dogs or nonhuman primates (NHPs). A 2022 IQ DruSafe survey revealed a modest increase in minipig use by pharmaceutical companies compared with a prior 2014 survey, primarily in the development of oral small molecules and parenteral protein molecules. Some companies considered using minipigs more often due to NHP shortages and regional ethical concerns with using NHPs and dogs. However, for most pharmaceutical companies, minipigs still represent ≤5% of their nonrodent animal use. Key challenges noted by companies to wider adoption of minipigs were high test article requirement, limited historical control data, and lack of relevant reagents or assays. Additionally, some companies expressed uncertainties about contract research organization (CRO) capabilities and experience, a perception not shared by respondent CROs. These latest survey results indicate persistence of many concerns previously identified in 2014. Several case studies are included to illustrate areas of expanded minipig use as well as the challenges that hinder broader adoption. Ongoing, focused, and industry-wide initiatives to address the identified or perceived challenges may lead to more frequent or routine consideration of minipigs as a test species in pharmaceutical R&D.

Predicting Human Subcutaneous Bioavailability of Therapeutic Monoclonal Antibodies from Systemic Clearance and Volume of Distribution

Subcutaneous delivery of monoclonal antibody therapeutics is often preferred to intravenous delivery due to better patient compliance and overall lower cost to the healthcare system. However, the systemic absorption of biologics dosed subcutaneously is often incomplete. The aim of this work was to describe a human bioavailability prediction method for monoclonal antibodies delivered subcutaneously that utilizes intravenous pharmacokinetic parameters as input. A two-compartment pharmacokinetic model featuring a parallel-competitive absorption pathway and a presystemic metabolism pathway was employed. A training data set comprised 19 monoclonal antibodies (geometric mean bioavailability of 68%), with previously reported human pharmacokinetic parameters, while a validation set included data compiled from 5 commercial drug products (geometric mean bioavailability of 69%). A single fitted absorption rate constant, paired with compound-specific estimates of presystemic metabolism rate proportional to compound-specific systemic clearance parameters, resulted in calculations of human subcutaneous bioavailability closely mimicking clinical data in the training data set with a root-mean-square error of 5.5%. Application of the same approach to the validation data set resulted in predictions characterized by 12.6% root-mean-square error. Factors that may have impacted the prediction accuracy include a limited number of validation data set compounds and an uncertainty in the absorption rate, which were subsequently discussed. The predictive method described herein provides an initial estimate of the subcutaneous bioavailability based exclusively on pharmacokinetic parameters available from intravenous dosing.

Infective complications in cancer patients treated with subcutaneous versus intravenous trastuzumab and rituximab: An individual patient data meta-analysis

BACKGROUND

Investigation of infection risk with subcutaneous versus intravenous trastuzumab and rituximab administration in an individual patient data (IPD) and published data meta-analysis of randomised controlled trials (RCTs).

METHODS

Databases were searched to September 2021. Primary outcomes were serious and high-grade infection. Relative-risk (RR) and 95% confidence intervals (95%CI) were calculated using random-effects models.

RESULTS

IPD meta-analysis (6 RCTs, 2971 participants, 2320 infections) demonstrated higher infection incidence with subcutaneous versus intravenous administration, without reaching statistical significance (serious: 12.2% versus 9.3%, RR 1.28, 95%CI 0.93to1.77, P = 0.13; high-grade: 12.2% versus 9.9%, RR 1.32, 95%CI 0.98to1.77, P = 0.07). With exclusion of an outlying study in post-hoc analysis, increased risks were statistically significant (serious: 13.1% versus 8.4%, RR 1.53, 95%CI 1.14to2.06, P = 0.01; high-grade: 13.2% versus 9.3%, RR 1.56, 95%CI 1.16to2.11, P < 0.01). Published data meta-analysis (8 RCTs, 3745 participants, 648 infections) demonstrated higher incidence of serious (HR 1.31, 95%CI 1.02to1.68, P = 0.04) and high-grade (HR 1.52, 95%CI 1.17to1.98, P < 0.01) infection with subcutaneous versus intravenous administration.

CONCLUSIONS

Results suggest increased infection risk with subcutaneous versus intravenous administration, although IPD findings are sensitive to exclusion of one trial with inconsistent results and identified risk-of-bias. Ongoing trials may confirm findings. Clinical surveillance should be considered when switching to subcutaneous administration. PROSPERO registration CRD42020221866/CRD42020125376.

Anti-HER2 biparatopic antibody KJ015 has near-native structure, functional balanced high affinity, and synergistic efficacy with anti-PD-1 treatment in vivo

Currently approved human epidermal growth factor receptor 2 (HER2)-targeted antibody therapies are largely derived from trastuzumab, including trastuzumab-chemotherapy combinations, fixed-dose trastuzumab-pertuzumab combinations, and trastuzumab antibody-drug conjugates. To expand the options, bispecific antibodies, which may better utilize the benefits of combination therapy, are being developed. Among them, biparatopic antibodies (bpAbs) have shown improved efficacy compared to monoclonal antibody (mAb) combinations in HER2-positive patients. BpAbs bind two independent epitopes on the same antigen, which allows fine-tuning of mechanisms of action, including enhancement of on-target specificity and induction of strong antigen clustering due to the unique binding mode. To fully utilize the potential of bpAbs for anti-HER2 drug development, it is crucial to consider formats that offer stability and high-yield production, along with a functional balance between the two epitopes. In this study, we rationally designed a bpAb, KJ015, that shares a common light chain with two Fab arms and exhibits functionally balanced high affinity for two HER2 non-overlapping epitopes. KJ015 demonstrated high-expression titers over 7 g/L and stable physicochemical properties at elevated concentrations, facilitating subcutaneous administration with hyaluronidase. Moreover, KJ015 maintained comparable antibody-dependent cytotoxicity, phagocytosis, and complement-dependent cytotoxicity with trastuzumab plus pertuzumab. It exhibited enhanced synergy when administered subcutaneously with hyaluronidase and anti-PD-1 mAb in a mouse tumor model, suggesting promising clinical prospects for this combination.

Advancing Subcutaneous Dosing Regimens for Biotherapeutics: Clinical Strategies for Expedited Market Access

In recent years, subcutaneous administration of biotherapeutics has made significant progress. The self-administration market for rheumatoid arthritis has witnessed the introduction of additional follow-on biologics, while the first subcutaneous dosing options for monoclonal antibodies have become available for multiple sclerosis. Oncology has also seen advancements with the authorization of high-volume subcutaneous formulations, facilitated by the development of high-concentration formulations and innovative delivery systems. Regulatory and Health Technology Assessment bodies increasingly consider preference data in filing dossiers, particularly in evaluating novel drug delivery methods. The adoption of a pharmacokinetic-based clinical bridging approach has become standard for transitioning from intravenous to subcutaneous administration. Non-inferiority studies with pharmacokinetics as the only primary endpoint have started deviating from traditional randomization schemes, favoring the subcutaneous route and comparing with historical intravenous data. While nonclinical and computational models made progress in predicting safety and immunogenicity for subcutaneously dosed antibodies, clinical trial evidence remains essential due to inter-individual variations and the impact of formulation parameters on anti-drug antibody formation. Ongoing technological advancements and the expanding knowledge base on pharmacokinetic-pharmacodynamic correlation across specialty areas are expected to further accelerate clinical development of subcutaneous biologics.

Pharmacokinetic characterization, benefits and barriers of subcutaneous administration of monoclonal antibodies in oncology

OBJECTIVE

Therapeutic monoclonal antibodies in oncology are slowly becoming the dominant treatment option for many different cancer types. The main route of administration, infusion, requires extensive product preparations, patient hospitalization and close monitoring. Patient comfort improvement, staff workload reduction and cost savings dictated the development of subcutaneous formulations. The aim of this review is to present pharmacokinetic characteristics of subcutaneous products, discuss the differences between intravenous and subcutaneous routes and to point out the advantages as well as challenges of administration route shift from the formulation development and pharmacometric angle.

DATA SOURCES

Food and Drug administration's Purple book database and electronic medicines compendium were used to identify monoclonal antibodies in oncology approved as subcutaneous forms. Using keywords subcutaneous, monoclonal antibodies, pharmacokinetics, model, as well as specific drugs previously identified, both PubMed and ScienceDirect databases were researched.

DATA SUMMARY

There are currently six approved subcutaneous onco-monoclonal antibodies on the market. For each of them, exposure to the drug was similar in relation to infusion, treatment effectiveness was the same, administration was well tolerated by the patients and costs of the medical service were reduced.

CONCLUSION

Development of subcutaneous forms for existing and emerging new monoclonal antibodies for cancer treatment as well as shifting from administration via infusion should be encouraged due to patient preference, lower costs and overall lack of substantial differences in efficacy and safety between the two routes.

Customer-centric product presentations for monoclonal antibodies

Delivering customer-centric product presentations for biotherapeutics, such as monoclonal antibodies (mAbs), represents a long-standing and paramount area of engagement for pharmaceutical scientists. Activities include improving experience with the dosing procedure, reducing drug administration-related expenditures, and ultimately shifting parenteral treatments outside of a controlled healthcare institutional setting. In times of increasingly cost-constrained markets and reinforced with the coronavirus pandemic, this discipline of "Product Optimization" in healthcare has gained momentum and changed from a nice-to-have into a must. This review summarizes latest trends in the healthcare ecosystem that inform key strategies for developing customer-centric products, including the availability of a wider array of sustainable drug delivery options and treatment management plans that support dosing in a flexible care setting. Three disease area archetypes with varying degree of implementation of customer-centric concepts are introduced to highlight relevant market differences and similarities. Namely, rheumatoid arthritis and inflammatory bowel disease, multiple sclerosis, and oncology have been chosen due to differences in the availability of subcutaneously dosed and ready-to-use self-administration products for mAb medicines and their follow-on biologics. Different launch scenarios are described from a manufacturer's perspective highlighting the necessity of platform approaches. To unfold the full potential of customer-centric care, value-based healthcare provider reimbursement schemes that incentivize the efficiency of care need to be broadly implemented.

Mechanistic Modeling of the Effect of Recombinant Human Hyaluronidase (rHuPH20) on Subcutaneous Delivery of Cetuximab in Rats

PURPOSE

To evaluate the duration of effect of rHuPH20 on SC absorption of cetuximab and to develop a mechanistic pharmacokinetic model linking the kinetics of rHuPH20 action with hyaluronan (HA) homeostasis and absorption of cetuximab from the SC space.

METHODS

Serum pharmacokinetics of cetuximab was evaluated after IV and SC dosing at 0.4 and 10 mg/kg (control groups). In test groups, SC cetuximab was administered simultaneously with rHuPH20 (Co-Injection) or 12 h after injection of rHuPH20 (Pre-Injection). Mechanistic pharmacokinetic model was developed to simultaneously capture cetuximab kinetics in all groups.

RESULTS

Administration of rHuPH20 resulted in a faster absorption of cetuximab; the difference between co-injection and pre-injection groups appeared to be dependent on the dose level. The model combined three major components: kinetics of rHuPH20 at SC site; HA homeostasis and its disruption by rHuPH20; and cetuximab systemic disposition and the effect of HA disruption on cetuximab SC absorption. The model provided good description of experimental data obtained in this study and collected previously.

CONCLUSIONS

Proposed model can serve as a potential translational framework for capturing the effect of rHuPH20 across multiple preclinical species and in human studies and can be used for optimization of SC delivery of biotherapeutics.

Ustekinumab pharmacokinetics after subcutaneous administration in swine model

BACKGROUND

Due to multiple similarities in the structure and physiology of human and pig skin, the pig model is extremely useful for biological drug testing after subcutaneous administration. Knowledge of the differences between subcutaneous injection sites could have a significant impact on the absorption phase and pharmacokinetic profiles of biological drugs.

OBJECTIVES

This study aimed to analyze the impact of administration site on pharmacokinetics and selected biochemical and hematological parameters after a single subcutaneous administration of ustekinumab in pigs. Drug concentrations in blood plasma were analyzed by enzyme-linked immunosorbent assay. Pharmacokinetic analyses were performed based on raw data using Phoenix WinNonlin 8.1 software and ThothPro v 4.1.

METHODS

The study included 12 healthy, female, large white piglets. Each group received a single dose of ustekinumab given as a 1 mg/kg subcutaneous injection into the internal part of the inguinal fold or the external part of the inguinal fold.

RESULTS

The differences in absorption rate between the internal and external parts of the inguinal fold were not significant. However, the time of maximal concentration, clearance, area under the curve calculated between zero and mean residence time and mean residence time between groups were substantially different (p > 0.05). The relative bioavailability after administration of ustekinumab into the external part of the inguinal fold was 40.36% lower than after administration of ustekinumab into the internal part of the inguinal fold.

CONCLUSIONS

Healthy breeding pigs are a relevant model to study the pharmacokinetic profile of subcutaneously administered ustekinumab.

Is weight-based IV dosing of trastuzumab preferable to SC fixed-dose in some patients? A systematic scoping review

Trastuzumab, a key treatment for HER2-positive breast cancer, is available in weight-based IV and fixed-dose (600 mg) SC formulations. While the Phase 3 HannaH trial indicated non-inferiority of the SC formulation, there is some concern that the target plasma concentration may not be reached in overweight/obese patients whereas low-body-weight patients may be at risk of toxicity. This scoping review evaluated whether overweight/obese patients are at risk of below-target exposure with fixed-dose SC trastuzumab, whether low-body-weight patients are at risk of increased toxicity, especially cardiotoxicity, and whether IV and SC trastuzumab are equivalent in terms of treatment-emergent adverse events (TEAEs) (e.g. infections). Thirty-seven publications that met the eligibility criteria were included. Body weight is not an important determinant of exposure to trastuzumab at steady state (i.e. pre-dose cycle 8); however, real-world evidence suggests that the target concentration (20 μg/mL) may not be reached with the first SC dose in overweight/obese patients. There is no evidence that low-body-weight patients are at increased risk of cardiotoxicity with SC trastuzumab, although this may be confounded by the higher rate of cardiovascular comorbidities in overweight patients. In Phase 3 trials, SC trastuzumab was associated with higher rates of ISRs, ADAs and SAEs, the latter often requiring hospitalization and occurring during adjuvant treatment when patients are not burdened by chemotherapy. The route of administration of trastuzumab (IV vs SC) in different treatment settings should be discussed with the patient, taking into account the risks and benefits associated with each route.

Quantitative Clinical Pharmacology Supports the Bridging from i.v. Dosing and Approval of s.c. Rituximab in B-Cell Hematological Malignancies

A fixed-dose subcutaneous (s.c.) formulation of the anti-CD20 antibody, rituximab, has been developed to address safety, infusion time, and patient comfort concerns relating to intravenous (i.v.) dosing, and has been approved based upon a pharmacokinetic (PK)-clinical bridging strategy, which demonstrated noninferiority of s.c. vs. i.v. dosing in malignancies, including follicular lymphoma (FL) and chronic lymphocytic leukemia (CLL). A clinical development plan was undertaken to identify rituximab s.c. doses achieving noninferior exposure to rituximab i.v., and to confirm PK-clinical bridging, with the same efficacy and similar safety. This drew upon data from 1,579 patients with FL, CLL, or diffuse large B-cell lymphoma in 5 clinical studies, and showed minimum steady-state serum concentration (C_trough ) as the most appropriate exposure bridging measure. Population PK models were developed, simulations were run using covariates and PK parameters from clinical studies, and exposure-efficacy and -safety analyses performed. Population PKs showed a two-compartment model with time-dependent and -independent clearances. Clearance and volume were predominantly influenced by body surface area; disposition and elimination were similar for the s.c. and i.v. formulations. After s.c. administration, patients with FL and CLL achieved noninferior exposures to i.v. dosing. Overall, rituximab exposure and route of administration did not influence clinical responses in patients with FL or CLL, and there was no association between exposure and safety events. C_trough was shown to be an effective pharmacologic-clinical bridging parameter for rituximab in patients with FL or CLL. Clinically effective exposures are achieved with either s.c. or i.v. dosing.

Results of a Dose-Finding Phase 1b Study of Subcutaneous Atezolizumab in Patients With Locally Advanced or Metastatic Non-Small Cell Lung Cancer

Intravenous (IV) atezolizumab is approved for non-small cell lung and other cancers. Subcutaneous (SC) atezolizumab coformulated with recombinant human hyaluronidase, a permeation enhancer for SC dispersion and absorption, is being developed to improve treatment options, reduce burden, and increase efficiency for patients and practitioners. IMscin001 (NCT03735121), a 2-part, open-label, global, multicenter, phase 1b/3 study, is evaluating the pharmacokinetics (PK), safety, and efficacy of SC atezolizumab. The part 1 (phase 1b) objective was determination of an SC atezolizumab dose yielding a serum trough concentration (C_trough ) comparable with IV. Patients enrolled in 3 cohorts received SC atezolizumab 1800 mg (thigh) once (cohort 1), 1200 mg (thigh) every 2 weeks for 3 cycles (cohort 2), or 1800 mg (abdomen) every 3 weeks cycle 1, then cycles 2 and 3 (thigh) every 3 weeks (cohort 3). In subsequent cycles, IV atezolizumab 1200 mg every 3 weeks was administered until loss of clinical benefit. SC atezolizumab 1800 mg every 3 weeks and 1200 mg every 2 weeks provided similar C_trough and area under the curve values in cycle 1 to the corresponding IV atezolizumab reference, was well tolerated, and exhibited a safety profile consistent with the established IV formulation. Exposure following SC injection in the abdomen was lower (20%, 28%, and 27% for C_trough , maximum concentration, and area under the concentration-time curve from time 0 to day 21, respectively) than in the thigh. Part 1 SC and IV PK data were analyzed using a population PK modeling approach, followed by simulations. Part 2 (phase 3) will now be initiated to demonstrate that SC atezolizumab PK exposure is not lower than that of IV.

In Situ Crosslinked Hydrogel Depot for Sustained Antibody Release Improves Immune Checkpoint Blockade Cancer Immunotherapy

The therapeutic inhibition of immune checkpoints, including cytotoxic T lymphocyte-associated protein (CTLA)-4 and programmed cell death 1 (PD-1), through the use of function blocking antibodies can confer improved clinical outcomes by invigorating CD8⁺ T cell-mediated anticancer immunity. However, low rates of patient responses and the high rate of immune-related adverse events remain significant challenges to broadening the benefit of this therapeutic class, termed immune checkpoint blockade (ICB). To overcome these significant limitations, controlled delivery and release strategies offer unique advantages relevant to this therapeutic class, which is typically administered systemically (e.g., intravenously), but more recently, has been shown to be highly efficacious using locoregional routes of administration. As such, in this paper, we describe an in situ crosslinked hydrogel for the sustained release of antibodies blocking CTLA-4 and PD-1 signaling from a locoregional injection proximal to the tumor site. This formulation results in efficient and durable anticancer effects with a reduced systemic toxicity compared to the bolus delivery of free antibody using an equivalent injection route. This formulation and strategy thus represent an approach for achieving the efficient and safe delivery of antibodies for ICB cancer immunotherapy.

Understanding Inter-Individual Variability in Monoclonal Antibody Disposition

Monoclonal antibodies (mAbs) are currently the largest and most dominant class of therapeutic proteins. Inter-individual variability has been observed for several mAbs; however, an understanding of the underlying mechanisms and factors contributing to inter-subject differences in mAb disposition is still lacking. In this review, we analyze the mechanisms of antibody disposition and the putative mechanistic determinants of inter-individual variability. Results from in vitro, preclinical, and clinical studies were reviewed evaluate the role of the neonatal Fc receptor and Fc gamma receptors (expression and polymorphism), target properties (expression, shedding, turnover, internalization, heterogeneity, polymorphism), and the influence of anti-drug antibodies. Particular attention is given to the influence of co-administered drugs and disease, and to the physiological relevance of covariates identified by population pharmacokinetic modeling, as determinants of variability in mAb pharmacokinetics.

Safety profile of subcutaneous trastuzumab in patients with HER2-positive early breast cancer: The French HERmione non-interventional prospective study

Objectives

HERmione study was conducted to assess, in human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (eBC), the safety profile of subcutaneous (SC) formulation of trastuzumab in real-life in France.

Materials and methods

This prospective, non-interventional study included 511 patients planned to be treated in both neoadjuvant and adjuvant settings with a follow-up of 12 months maximum in 101 sites. The safety analyses concerned 505 patients. Primary endpoint was the description of systemic safety and local tolerability of the SC trastuzumab.

Results

The median age of patients was 58 years. Over the study, 2449 adverse events (AEs) occurred in 422 (83.6%) patients (asthenia, arthralgia, radiation skin injury, myalgia, hot flush and diarrhea in ≥10% of patients): 92 AEs (3.8%) were grade ≥3 (radiation skin injury in 1.8% of patients and febrile neutropenia in 1.4% of patients), 76 (3.1%) were serious (mainly febrile neutropenia in 1.4% of patients) and 336 (13.7%) were treatment-related (mainly injection site pain in 9.1% of patients). Congestive Heart Failure occurred in 58 (11.5%) patients and was related to treatment in 4.6% of patients. Only 34 AEs (1.4%) in 27 (5.4%) patients led to permanent treatment discontinuation. One death was assessed as not treatment-related. Quality of life (QoL) analyses showed no deterioration of global health status.

Conclusion

The HERmione study showed that, in a real-life setting, the safety of SC trastuzumab administered in HER2-positive eBC patients is consistent with data reported from previous clinical trials, without new safety concerns or QoL deterioration.

Subcutaneous Administration of Biotherapeutics: An Overview of Current Challenges and Opportunities

Subcutaneous delivery of biotherapeutics has become a valuable alternative to intravenous administration across many disease areas. Although the pharmacokinetic profiles of subcutaneous and intravenous formulations differ, subcutaneous administration has proven effective, safe, well-tolerated, generally preferred by patients and healthcare providers and to result in reduced drug delivery-related healthcare costs and resource use. The aim of this article is to discuss the differences between subcutaneous and intravenous dosing from both health-economic and scientific perspectives. The article covers different indications, treatment settings, administration volumes, and injection devices. We focus on biotherapeutics in rheumatoid arthritis (RA), immunoglobulin-replacement therapy in primary immunodeficiency (PI), beta interferons in multiple sclerosis (MS), and monoclonal antibodies (mAbs) in oncology. While most subcutaneous biotherapeutics in RA, PI, and MS are self-administered at home, mAbs for oncology are still only approved for administration in a healthcare setting. Beside concerns around the safety of biotherapeutics in oncology, a key challenge for self-administration in this area is that doses and dosing volumes can be comparatively large; however, this difficulty has recently been overcome to some extent by the development of high-concentration solutions, the use of infusion pumps, and the coadministration of the dispersion enhancer hyaluronidase. Furthermore, given the increasing number of biotherapeutics being considered for combination therapy and the high dosing complexity associated with these, especially when administered intravenously, subcutaneous delivery of fixed-dose combinations might be an alternative that will diminish these burdens on healthcare systems.

Pharmacokinetics of monoclonal antibodies and Fc-fusion proteins

There are many factors that can influence the pharmacokinetics (PK) of a mAb or Fc-fusion molecule with the primary determinant being FcRn-mediated recycling. Through Fab or Fc engineering, IgG-FcRn interaction can be used to generate a variety of therapeutic antibodies with significantly enhanced half-life or ability to remove unwanted antigen from circulation. Glycosylation of a mAb or Fc-fusion protein can have a significant impact on the PK of these molecules. mAb charge can be important and variants with pI values of 1-2 unit difference are likely to impact PK with lower pI values being favorable for a longer half-life. Most mAbs display target mediated drug disposition (TMDD), which can have significant consequences on the study designs of preclinical and clinical studies. The PK of mAb can also be influenced by anti-drug antibody (ADA) response and off-target binding, which require careful consideration during the discovery stage. mAbs are primarily absorbed through the lymphatics via convection and can be conveniently administered by the subcutaneous (sc) route in large doses/volumes with co-formulation of hyaluronidase. The human PK of a mAb can be reasonably estimated using cynomolgus monkey data and allometric scaling methods.

Subcutaneous Rituximab for the Treatment of B-Cell Hematologic Malignancies: A Review of the Scientific Rationale and Clinical Development

Rituximab (MabThera®/Rituxan®), a chimeric murine/human monoclonal antibody that binds specifically to the transmembrane antigen CD20, was the first therapeutic antibody to enter clinical practice for the treatment of cancer. As monotherapy and in combination with chemotherapy, rituximab has been shown to prolong progression-free survival and, in some indications overall survival, in patients with various B-cell malignancies, while having a well-established and manageable safety profile and a wide therapeutic window. As a result, rituximab is considered to have revolutionized treatment practices for patients with B-cell malignancies. A subcutaneous (SC) formulation of rituximab has been developed, comprising the same monoclonal antibody as the originally marketed formulation [rituximab concentrate for solution for intravenous (IV) infusion], and has undergone a detailed, sequential clinical development program. This program demonstrated that, at fixed doses, rituximab SC achieves non-inferior serum trough concentrations in patients with non-Hodgkin lymphoma and chronic lymphocytic leukemia, with comparable efficacy and safety relative to the IV formulation. The added benefit of rituximab SC was demonstrated in dedicated studies showing that rituximab SC allows for simplified and shortened drug preparation and administration times resulting in a reduced treatment burden for patients as well as improved resource utilization (efficiency) at the treatment facility. The improved efficiency of delivering rituximab's benefit to patients may broaden patient access to rituximab therapy in areas with low levels of healthcare resources, including IV-chair capacity constraints. This article is a companion paper to G. Salles, et al., which is also published in this issue.

FUNDING

F. Hoffmann-La Roche Ltd.

Perspectives on Subcutaneous Route of Administration as an Immunogenicity Risk Factor for Therapeutic Proteins

An increasing number of therapeutic proteins are being developed for delivery through the subcutaneous (SC) route of administration. Relative to intravenous (IV) administration, the SC route offers more convenience to patients, flexibility in dosing, and potential to reduce health care costs. There is a perception that SC administration can pose a higher immunogenicity risk than IV administration for a given protein. To evaluate whether there is a difference in therapeutic protein immunogenicity associated with administration routes, a more detailed understanding of the interactions with the immune system by each route is needed. Few approved therapeutic proteins have available clinical immunogenicity data sets in the public domain that represent both IV and SC administration routes. This has prevented a direct comparison of the 2 routes of administration across a large sample size. Of the 6 marketed products where SC and IV route-related incidences of anti-drug antibody (ADA) were available, 4 were associated with higher immunogenicity incidence with SC. In other cases, there was no apparent difference between the SC and IV routes. Overall, the ADA incidence was low (<15%) with no impact on safety or efficacy. The challenges associated with identifying specific risk factors unique to SC administration are discussed.

Population pharmacokinetic and exposure-response analysis for trastuzumab administered using a subcutaneous "manual syringe" injection or intravenously in women with HER2-positive early breast cancer

Purpose

To characterize the population pharmacokinetics (PKs) of subcutaneous (SC) and intravenous (IV) trastuzumab in early breast cancer (EBC), assess the impact of covariates on trastuzumab PK, and evaluate fixed (nonweight-based) dosing for the SC regimen administrated via handheld syringe.

Methods

Serum trastuzumab concentrations from 595 patients with HER2-positive EBC in the HannaH study (fixed 600 mg SC trastuzumab or weight-based IV trastuzumab) were analyzed using nonlinear mixed-effects modeling. Multiple logistic regression was used to assess the exposure–response relationships between PK, efficacy [pathologic complete response (pCR)], and safety [grade ≥3 adverse events (AEs)].

Results

Trastuzumab PK was described by a two-compartment model with parallel linear and nonlinear elimination and first-order SC absorption, with a bioavailability of 77 %. Estimated total clearance (CL) values were 0.18–0.22 L/day for steady-state trough/peak concentrations of 75–148 µg/mL; the estimate for central volume of distribution was 2.9 L. Body weight and alanine transaminase, while showing significant effects on PK, only explained 8 % of the variability in CL. Exposure–response analyses showed no relationship between PK, pCR, and grade ≥3 AEs for either regimen.

Conclusion

A fixed 600 mg SC dose of trastuzumab provides the desired exposure, with steady-state trough concentrations (35–123 μg/mL for the 5th–95th percentiles) above the historical target concentration of 20 μg/mL for efficacy. Fixed dosing is further supported by lack of an exposure–response relationship between PK, pCR, and grade ≥3 AEs. No dose adjustment per patient factors is required within the ranges studied.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-015-2922-5) contains supplementary material, which is available to authorized users.

Pharmacokinetics and safety of subcutaneous rituximab plus fludarabine and cyclophosphamide for patients with chronic lymphocytic leukaemia

AIMS

The aim of the phase Ib, two part SAWYER study (BO25341; NCT01292603) was to investigate the pharmacokinetics and safety of subcutaneous (s.c.) rituximab compared with intravenous (i.v.) rituximab, both in combination with fludarabine and cyclophosphamide (FC), as first line treatment for patients with chronic lymphocytic leukaemia (CLL).

METHODS

During part 1 (dose-finding), CLL patients received rituximab i.v. followed by a single dose of rituximab s.c. at one of three fixed doses (1400, 1600 or 1870 mg) in cycle 6. The primary objective was to identify a fixed s.c. dose that would achieve comparable rituximab serum trough concentrations (Ctrough ) to those achieved with the standard 4 weekly 500 mg m(-2) rituximab i.v. dose.

RESULTS

Fifty-five patients received a fixed dose of rituximab s.c., 16 received 1400 mg, 17 received 1600 mg and 22 received 1870 mg. The 1600 mg dose was predicted to achieve non-inferior Ctrough to standard rituximab i.v.

TREATMENT

The rituximab s.c. safety profile was comparable with rituximab i.v., except that local administration-related reactions, mainly mild/moderate injection site reactions, occurred more frequently with rituximab s.c., which was not unexpected. Subcutaneous administration was preferred to i.v. administration by >90% of patients and nurses (n = 112).

CONCLUSIONS

SAWYER part 1 data predict that rituximab s.c. 1600 mg will achieve non-inferior Ctrough concentrations to rituximab i.v. 500 mg m(-2) , administered 4 weekly. This fixed s.c. dose is currently undergoing formal non-inferiority assessment in SAWYER part 2. In future, CLL treatment regimens comprising rituximab s.c. and oral FC could substantially reduce i.v. chair time.

Role of subcutaneous formulation of trastuzumab in the treatment of patients with HER2-positive breast cancer

Tumors in about 15% of patients with breast cancer overexpress HER2. Trastuzumab (Herceptin(®); F. Hoffmann-La Roche, Basel, Switzerland) is a humanized monoclonal antibody against HER2. While the introduction of trastuzumab has changed the natural course of HER2-positive breast cancer, the need for repeated administration of the drug over a prolonged period of time represents a challenge. Similarly to other chronic disorders, subcutaneous administration of monoclonal antibodies may be of advantage in this setting. The results of a prospective randomized Phase III study have demonstrated that subcutaneous trastuzumab is noninferior compared with the intravenous administration of the drug in terms of efficacy (assessed as pathological complete response rate) as well as in pharmacokinetic parameters. Moreover, another prospective randomized study showed that an overwhelming majority of patients prefer subcutaneous over intravenous trastuzumab. The advent of subcutaneous trastuzumab represents an important progress in the concept of cancer management that is based also on patient choice and preferences.

Evaluating the administration costs of biologic drugs: development of a cost algorithm

Biologic drugs, as with all other medical technologies, are subject to a number of regulatory, marketing, reimbursement (financing) and other demand-restricting hurdles applied by healthcare payers. One example is the routine use of cost-effectiveness analyses or health technology assessments to determine which medical technologies offer value-for-money. The manner in which these assessments are conducted suggests that, holding all else equal, the economic value of biologic drugs may be determined by how much is spent on administering these drugs or trade-offs between drug acquisition and administration costs. Yet, on the supply-side, it seems very little attention is given to how manufacturing and formulation choices affect healthcare delivery costs. This paper evaluates variations in the administration costs of biologic drugs, taking care to ensure consistent inclusion of all relevant cost resources. From this, it develops a regression-based algorithm with which manufacturers could possibly predict, during process development, how their manufacturing and formulation choices may impact on the healthcare delivery costs of their products.

Subcutaneous absorption of biotherapeutics: knowns and unknowns

Subcutaneous administration of biotherapeutics offers several potential advantages compared with intravenous administration. Many biotherapeutics, both marketed or in development, are administered via the subcutaneous route. This minireview provides an overview of the presystemic absorption processes following subcutaneous administration, the resulting pharmacokinetics after subcutaneous administration, and provides recent case examples of the development of subcutaneous administered drugs with a focus on monoclonal antibodies. Subcutaneous absorption of biotherapeutics is relatively slow and mostly incomplete. Knowledge of the subcutaneous tissue is important to understand the absorption kinetics after subcutaneous administration. Transport in the subcutis to the absorbing blood or lymph capillaries appears to be a major contributor to the slow subcutaneous absorption. Larger proteins (>20 kDa) are mostly absorbed via the lymphatic system, although potential species differences are not fully understood yet. Also, the presystemic catabolism leading to incomplete bioavailability is little understood, both the involved enzymes and its translation across species. For IgGs, binding to the neonatal Fc receptor is important to obtain a high bioavailability. Overall, several aspects of subcutaneous absorption are still poorly understood, which hampers, e.g., translation across species. Further research in this area is warranted.

Pharmacokinetic modeling of the subcutaneous absorption of therapeutic proteins

Subcutaneous injection is an important route of administration for therapeutic proteins that provides several advantages over other modes of parenteral delivery. Despite extensive clinical use, the exact mechanism underlying subcutaneous absorption of proteins is not completely understood, and the accuracy of prediction of absorption of biotherapeutics in humans remains unsatisfactory. This review summarizes a variety of models that have been developed for describing the pharmacokinetics of therapeutic proteins administered by subcutaneous injection, including single- and dual-pathway absorption models. Modeling of the lymphatic uptake and redistribution, absorption of monoclonal antibodies and insulin, and population analysis of protein absorption are discussed. The review also addresses interspecies modeling and prediction of absorption in humans, highlights important factors affecting the absorption processes, and suggests approaches for future development of mechanism-based absorption models.

Cardiovascular toxicity associated with adjuvant trastuzumab therapy: prevalence, patient characteristics, and risk factors

Before the advent of the human epidermal growth factor receptor 2 (HER2)-targeted monoclonal antibody trastuzumab, HER2-positive breast cancers were difficult to treat and had a poor prognosis. Adjuvant trastuzumab is now an important part of the treatment regimen for many women with HER2-positive breast cancer and has undoubtedly resulted in a significant improvement in prognosis, but it is associated with a risk for cardiotoxicity. In this review, we describe the prevalence, patient characteristics, and risk factors for cardiotoxicity associated with use of adjuvant trastuzumab. Understanding risk factors for trastuzumab-induced cardiotoxicity and appropriate patient monitoring during trastuzumab treatment allows for safe and effective use of this important adjuvant therapy.

Subcutaneous Administration of Monoclonal Antibodies in Oncology

Treatment with monoclonal antibodies (mabs) has become an established component of oncological therapy. The monoclonal antibodies available for this purpose are mainly administered intravenously in individually adapted doses according to body weight over longer treatment times. For other chronic diseases such as, for example, diabetes mellitus, the subcutaneous administration of drugs is an established therapy option. For the subcutaneous administration of larger volumes as needed for mab solutions the extracellular matrix of the subcutaneous tissue represents a problem. The co-formulation with recombinant human hyaluronidase makes the relatively pain-free administration of larger fluid volumes and thus the subcutaneous administration of monoclonal antibodies possible, as illustrated by the development of a subcutaneous formulation of trastuzumab. This constitutes a less invasive, time-optimised and flexible form of administration for patients with HER2-positive breast cancer that, with its fixed dosing possibilities, contributes to therapeutic safety. The example of trastuzumab shows that the subcutaneous administration of monoclonal antibodies can simplify oncological long-term therapy not only for the patients but also for the medical personnel.

Subcutaneous trastuzumab: a review of its use in HER2-positive breast cancer

Trastuzumab (Herceptin®) is a humanized IgG1 monoclonal antibody that is an efficacious treatment for HER2-positive breast and gastric cancers. Subcutaneous trastuzumab is a new formulation approved in the European Union for use in patients with early or metastatic breast cancer. In the randomized, open-label, multinational HannaH (enHANced treatment with NeoAdjuvant Herceptin) study of neoadjuvant/adjuvant trastuzumab in patients with early HER2-positive breast cancer, the pharmacokinetics of neoadjuvant subcutaneous trastuzumab were similar to those after intravenous administration, meeting the noninferiority criterion for mean predose trough concentrations, as assessed prior to surgery (primary pharmacokinetic endpoint). Trastuzumab blood concentrations throughout the dosing interval remained above those considered necessary for anticancer activity. In this study, the pathologic complete response rates (primary efficacy endpoint) were 45.4 and 40.7 % in the subcutaneous and intravenous administration groups, respectively, meeting a study noninferiority criterion. In the randomized, open-label, crossover, multinational PrefHer study of neoadjuvant/adjuvant or adjuvant trastuzumab in early HER2-positive breast cancer, subcutaneous administration of trastuzumab was preferred over intravenous administration by >85 % of patients, most commonly because it was time saving and induced less pain and discomfort. In the HannaH study, the tolerability profile of subcutaneous trastuzumab was similar to that of intravenous trastuzumab, except that the rate of serious adverse events was 21 % (vs. 12 % with intravenous administration), partly because of more infections with subcutaneous administration. Whether this finding is of any clinical significance should emerge from ongoing studies. On the evidence, subcutaneous trastuzumab is an effective and generally well-tolerated treatment option that is preferred by patients over intravenous administration.

Use of a population pharmacokinetic approach for the clinical development of a fixed-dose subcutaneous formulation of trastuzumab

A new subcutaneous (s.c.) trastuzumab formulation provides savings in terms of time and is preferred by patients and health care professionals relative to standard intravenous (i.v.) administration due to simpler and more rapid administration (2-5 minutes). Selection of the s.c. dose was based on a pharmacokinetic bridging approach that aimed to achieve noninferior trastuzumab serum trough concentrations (Ctrough) vs. reference i.v. administration. Using population modeling and simulation, we showed that a fixed 600-mg trastuzumab s.c. dose, administered thrice-weekly (Q3W) without a loading dose, would provide Ctrough (predose Cycle 8) and area under the time-concentration curve (AUC0-21 days, Cycle 7) at least as high as Q3W i.v. administration. The model was retrospectively validated using observed pharmacokinetic data from an independent phase III study of (neo)adjuvant trastuzumab (HannaH). These results provide a strong pharmacokinetic rationale for the trastuzumab s.c. 600-mg fixed dose, supported by the noninferior efficacy of this regimen vs. reference i.v. administration.CPT Pharmacometrics Syst. Pharmacol. (2014) 3, e87; doi:10.1038/psp.2013.63; advance online publication 2 January 2014.