No abstract

The first anticancer biosimilars have entered clinical use, with many others under clinical development. Like all biologics, biosimilars may elicit unwanted immune responses that can significantly impact clinical efficacy and safety. Head-to-head immunogenicity assessment of biosimilars and their reference biologics should, therefore, be a critical component of a biosimilar's clinical development program. Various bioanalytical platforms may be used to detect and characterize immune responses, each having relative strengths and weaknesses. To fully recognize the clinical relevance of such data, regulators must be able to interpret immunogenicity results in an assay-specific context as well as in perspective of clinical pharmacology, efficacy and safety. Herein, we discuss current challenges imposed by global regulatory requirements for immunogenicity assessment of biosimilars.

Introduction: Biologics are highly complex drugs and many of their characteristics are defined by the manufacturing process. In recent years, several monoclonal antibody (mAb) biologics, which were hitherto only available for intravenous (IV) administration, have been reformulated for subcutaneous (SC) administration. Reformulation involves alterations to the established manufacturing process and it has been argued that a SC formulation should therefore be considered a biosimilar version of its previously approved IV formulation. Areas covered: Developing an SC version of an approved IV mAb product requires the adaptation of its formulation and route of administration. This process is illustrated via case examples of trastuzumab and rituximab and summarize what data requirements support the regulatory approval of these new formulations. Furthermore, we discuss similarities and differences between the development of an SC product vs. the development of a biosimilar. Expert opinion: The production process of a biosimilar is independently established from the very beginning, while the development of an SC formulation affects later stages of an already established production process and builds on extensive experience with the IV formulation. Considering these fundamentally different situations, a biologic product reformulated for SC administration should not be considered a 'biosimilar' version of itself. ARTICLE HISTORY

Contusion spinal injury of different severity was induced by the weight drop method in male rats by dropping standard weight from the heights of 6.5, 12.5, 25, and 50 mm on the spine after laminectomy at the Th9 level. The dynamics of recovery of voluntary movements was evaluated over 8 weeks after the operation by comparing the traditional semiquantitative BBB score with objective parameters of exercise tests. Exercise tests detected cessation of spontaneous recovery of impaired functions 1-2 weeks earlier than the BBB method. The maximum performance according to the rotarod and narrowing track tests was 20-40% lower than the level of voluntary movement recovery evaluated by the BBB score. No appreciable differences between the levels of maximum recovery of voluntary movements (BBB score) and swimming velocity were detected. According to morphometric analysis of the volumes of pathological cavities and intact white matter in the focus of injury, exercise tests adequately reflected the severity of spinal contusion in rats. Exercise tests used in the study are recommended for objective preclinical evaluation of the efficiency of new means for the treatment of spinal injuries.

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.