Trastuzumab biosimilar SB3 shows equivalence
What happened
A phase III study found the trastuzumab biosimilar SB3 to be equivalent to the reference product in HER2‑positive breast cancer, with non‑inferior pathologic complete response rates reported. As biosimilars scale, subtle differences can appear in real‑world AE profiles, so this trial result will likely prompt heightened pharmacovigilance during market uptake. Sponsors and regulators are increasingly relying on analytical comparability plus targeted post‑market safety monitoring to track any emergent differences. (onclive.com)
Why it matters
Samsung Bioepis’s trastuzumab biosimilar SB3 — marketed as Ontruzant — was tested in a randomized phase III trial and produced similar tumor responses and a similar safety profile to the reference trastuzumab used before surgery in early breast cancer patients. (clf1.medpagetoday.com) Regulators accepted that data package and granted marketing authorizations: the European Commission approved Ontruzant in November 2017 and the U.S. Food and Drug Administration approved it in January 2019. (businesswire.com) (accessdata.fda.gov) The trial’s primary endpoint was breast pathologic complete response — defined as no remaining invasive tumor cells detected in the breast specimen after pre‑surgery therapy — and the study used prespecified equivalence criteria (an accepted statistical window within which two treatments are considered clinically similar). In the per‑protocol population (about 800 patients), the biosimilar arm and the reference arm met the trial’s predefined equivalence range based on the ratio of response rates, while the absolute difference in response rates had a confidence interval that extended slightly beyond the prespecified margin; full methods and margins are reported in the Journal of Clinical Oncology report. (clf1.medpagetoday.com) During analytical comparability work, developers identified a downward shift in an immune effector function called antibody‑dependent cell‑mediated cytotoxicity (ADCC) in some lots of the reference product; ADCC is the mechanism by which an antibody flags a target cell so immune cells can recognize and kill it, and that activity is sensitive to specific sugar (glycan) patterns on the antibody that affect Fcγ receptor IIIa binding. The lot‑to‑lot change was linked to altered glycosylation profiles and reduced FcγRIIIa binding in the affected reference lots. (link.springer.com) (read.qxmd.com) A post‑hoc long‑term follow‑up and extension analyses showed that patients who received reference‑product lots with the reduced ADCC signature had lower event‑free survival at follow‑up compared with patients who received unshifted lots or the biosimilar in the extension cohort (the extension enrolled 367 patients: 186 in the SB3 arm and 181 in the reference arm); longer‑term cardiac safety analyses, however, found comparable cardiac outcomes between SB3 and reference trastuzumab in extended follow‑up. (researchgate.net) (jamanetwork.com) Regulatory and pharmacovigilance implications: both U.S. and European frameworks expect thorough analytical comparability before approval and ongoing post‑market safety monitoring afterwards, including risk management plans and periodic safety reporting; FDA’s recent best‑practice documents on postmarketing surveillance reinforce risk‑based active monitoring approaches that sponsors should align to, and EMA’s good pharmacovigilance practices require continuous safety signal detection in centralized databases. Given the SB3/Herceptin lot issues, sponsors should explicitly track batch identifiers, monitor critical quality attributes (glycosylation, FcγRIIIa binding, ADCC) as potential root causes for emergent outcome differences, and ensure RMPs and post‑authorization study commitments capture analyses by lot and glycoform where clinically plausible. (fda.gov 1) (fda.gov 2) (ema.europa.eu) (centerforbiosimilars.com)
Key numbers
- A phase III study found the trastuzumab biosimilar SB3 to be equivalent to the reference product in HER2‑positive breast cancer, with non‑inferior pathologic complete response rates reported.
- (clf1.medpagetoday.com) Regulators accepted that data package and granted marketing authorizations: the European Commission approved Ontruzant in November 2017 and the U.S.
- Food and Drug Administration approved it in January 2019.
- (fda.gov 1) (fda.gov 2) (ema.europa.eu) (centerforbiosimilars.com)
What happens next
- As biosimilars scale, subtle differences can appear in real‑world AE profiles, so this trial result will likely prompt heightened pharmacovigilance during market uptake.
Quick answers
What happened in Trastuzumab biosimilar SB3 shows equivalence?
A phase III study found the trastuzumab biosimilar SB3 to be equivalent to the reference product in HER2‑positive breast cancer, with non‑inferior pathologic complete response rates reported. As biosimilars scale, subtle differences can appear in real‑world AE profiles, so this trial result will likely prompt heightened pharmacovigilance during market uptake. Sponsors and regulators are increasingly relying on analytical comparability plus targeted post‑market safety monitoring to track any emergent differences. (onclive.com)
Why does Trastuzumab biosimilar SB3 shows equivalence matter?
Samsung Bioepis’s trastuzumab biosimilar SB3 — marketed as Ontruzant — was tested in a randomized phase III trial and produced similar tumor responses and a similar safety profile to the reference trastuzumab used before surgery in early breast cancer patients. (clf1.medpagetoday.com) Regulators accepted that data package and granted marketing authorizations: the European Commission approved Ontruzant in November 2017 and the U.S. Food and Drug Administration approved it in January 2019. (businesswire.com) (accessdata.fda.gov) The trial’s primary endpoint was breast pathologic complete response — defined as no remaining invasive tumor cells detected in the breast specimen after pre‑surgery therapy — and the study used prespecified equivalence criteria (an accepted statistical window within which two treatments are considered clinically similar). In the per‑protocol population (about 800 patients), the biosimilar arm and the reference arm met the trial’s predefined equivalence range based on the ratio of response rates, while the absolute difference in response rates had a confidence interval that extended slightly beyond the prespecified margin; full methods and margins are reported in the Journal of Clinical Oncology report. (clf1.medpagetoday.com) During analytical comparability work, developers identified a downward shift in an immune effector function called antibody‑dependent cell‑mediated cytotoxicity (ADCC) in some lots of the reference product; ADCC is the mechanism by which an antibody flags a target cell so immune cells can recognize and kill it, and that activity is sensitive to specific sugar (glycan) patterns on the antibody that affect Fcγ receptor IIIa binding. The lot‑to‑lot change was linked to altered glycosylation profiles and reduced FcγRIIIa binding in the affected reference lots. (link.springer.com) (read.qxmd.com) A post‑hoc long‑term follow‑up and extension analyses showed that patients who received reference‑product lots with the reduced ADCC signature had lower event‑free survival at follow‑up compared with patients who received unshifted lots or the biosimilar in the extension cohort (the extension enrolled 367 patients: 186 in the SB3 arm and 181 in the reference arm); longer‑term cardiac safety analyses, however, found comparable cardiac outcomes between SB3 and reference trastuzumab in extended follow‑up. (researchgate.net) (jamanetwork.com) Regulatory and pharmacovigilance implications: both U.S. and European frameworks expect thorough analytical comparability before approval and ongoing post‑market safety monitoring afterwards, including risk management plans and periodic safety reporting; FDA’s recent best‑practice documents on postmarketing surveillance reinforce risk‑based active monitoring approaches that sponsors should align to, and EMA’s good pharmacovigilance practices require continuous safety signal detection in centralized databases. Given the SB3/Herceptin lot issues, sponsors should explicitly track batch identifiers, monitor critical quality attributes (glycosylation, FcγRIIIa binding, ADCC) as potential root causes for emergent outcome differences, and ensure RMPs and post‑authorization study commitments capture analyses by lot and glycoform where clinically plausible. (fda.gov 1) (fda.gov 2) (ema.europa.eu) (centerforbiosimilars.com)
