Biosimilar biologics: never identical but close enough

Physicochemical and functional characterization of trastuzumab-dkst, a trastuzumab biosimilar

Aims: Preclinical comparative similarity studies of trastuzumab-dkst, a Herceptin^® biosimilar, are reported. Materials & methods: Primary sequence and higher order structure and pharmacological mechanisms of action were compared using multiple techniques. Pharmacokinetics and repeat-dose toxicity were assessed in cynomolgus monkeys. Results: Primary structures were identical; secondary and tertiary structures were highly similar. Non-significant differences were observed for charge heterogeneity. Twelve of 13 glycan species were highly similar, with slightly higher total mannose levels in trastuzumab-dkst. FcγR and FcRn binding activity was highly similar. Each drug equally inhibited HER2⁺ cell proliferation, demonstrating equivalent relative potency in mediating HER2⁺ cell cytolysis by antibody-dependent cellular cytotoxicity. Pharmacokinetic and toxicological profiles in cynomolgus monkeys were similar. Conclusion: Trastuzumab-dkst, US-licensed trastuzumab and EU-approved trastuzumab demonstrate high structural and functional similarity.

A pharmacokinetics phase 1 bioequivalence study of the trastuzumab biosimilar MYL-1401O vs. EU-trastuzumab and US-trastuzumab

AIMS

Trastuzumab is a humanized monoclonal antibody that binds the human epidermal growth factor receptor 2 (HER2) oncoprotein and is an effective therapy for HER2-overexpressing breast cancer. MYL-1401O is a trastuzumab biosimilar. Here, we report results from a phase 1 study that investigated bioequivalence among MYL-1401O, reference EU-trastuzumab and US-trastuzumab.

METHODS

This single-centre, randomized, double-blind, three-arm, parallel-group, phase 1 study was conducted in healthy adult male volunteers. Subjects were randomized 1:1:1 to receive a single 8 mg kg^-1 dose of MYL-1401O, EU-trastuzumab or US-trastuzumab as a 90-min intravenous infusion. The primary objective was to assess PK similarity among all three products. Primary endpoints assessed were peak serum concentration (Cmax), area under the serum concentration-time curve from time of dosing to time of last quantifiable concentration and from time of dosing to infinity. Secondary endpoints included time of Cmax, elimination rate constant, half-life, safety and immunogenicity.

RESULTS

Of 132 subjects enrolled (44/treatment), 120 (MYL-1401O, n = 42; EU-trastuzumab, n = 41; US-trastuzumab, n = 37) were included in the PK analysis. The 90% confidence intervals of the ratios of geometric means for the primary endpoints were bounded within the predefined bioequivalence criterion of 80-125%. Secondary endpoints time of Cmax, elimination rate constant and half-life were similar among groups. All treatment-emergent adverse events were mild or moderate, similar across groups and no serious adverse events were reported. No treatment-related antidrug antibodies were detected.

CONCLUSIONS

MYL-1401O was well tolerated and demonstrated PK and safety profiles similar to EU-trastuzumab and US-trastuzumab in healthy volunteers (ClinicalTrials.gov, NCT02594761).

Medical and ethical considerations on hematopoietic stem cells mobilization for healthy donors

Hematopoietic stem cell transplantation is a common procedure potentially beneficial to many individuals with cancer, hematological, or inherited disorders, and has highlighted the need of related or unrelated donors to perform allograft. Donation of hematopoietic stem cells, either through bone marrow harvest or peripheral blood stem cell collection, is well-established and widespread. Over the past two decades, the peripheral blood stem cell collection by aphaeresis has become the main source of hematopoietic stem cells for transplantation, due to faster engraftment and practicability and lower risk of relapse for high-risk patients. For peripheral blood stem cell donation, donors require mobilization of hematopoietic stem cells from bone marrow into the blood stream. This is performed by growth factors injections. This article is a review of reported applications of growth factors (original granulocyte colony stimulating factor and its biosimilars), for healthy donors' peripheral blood stem cell mobilization, in terms of toxicity, side effects, efficacy and follow-up. There is still an ethical dilemma for clinicians involved in allograft, because they expose healthy donors to drugs. It is important to dispel some of the critical concerns regarding their use in healthy volunteers, particularly because they receive no personal therapeutic benefit from this procedure.

Update on biosimilars of granulocyte colony-stimulating factor - when no news is good news

PURPOSE OF REVIEW

With the approval of the first biosimilar granulocyte colony-stimulating factor (G-CSF), biosimilars - copies of therapeutic biologicals whose patent protection has expired - have finally reached the US healthcare market. Its advent is an occasion for a closer look at recent insights into biosimilar G-CSF and an attempt at prognosticating the future (future role) of biosimilars in general.

RECENT FINDINGS

Recent literature regarding biosimilar G-CSF orbits significantly around patient access and effects on healthcare expenditure. The advent of biosimilar G-CSF has induced unexpectedly large price reductions for short-acting G-CSF. On the clinical side, little excitement is tangible, probably appropriately so, since clinical data indicate nothing short of biological similarity. Although formal clinical trials are few, the plethora of case series and historic comparisons which have come forth offer reassurance about the appropriateness of the regulators' assessment of biosimilar G-CSF as indeed in all respects biologically similar to the originator.

SUMMARY

All evidence points to an overwhelming similarity of originator and biosimilar G-CSF in all indications. Overall clinical acceptance, albeit possibly significantly dictated by economic pressures, is good. Price reductions exceed predictions and may jeopardize the economic viability of biosimilar programs. A concurrent shift towards long-acting G-CSF ('biobetters') is observed in Europe.