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New I-SPY 2 Trial Arm to Evaluate Byondis' Antibody-Drug Conjugate in HER2-Low Breast Cancer

NEW YORK – Dutch biopharmaceutical company Byondis (formerly Synthon Biopharmaceuticals) said on Monday that Quantum Leap, the company sponsoring the ongoing Phase II/III I-SPY 2 trial for subgroups of women with breast cancer, has selected Byondis' antibody-drug conjugate SYD985 for inclusion in a new treatment arm of the study.

Specifically, the new investigational arm of I-SPY 2, which stands for "Investigation of Serial Studies to Predict Your Therapeutic Response With Imaging and Molecular Analysis 2," will pit SYD985 against standard-of-care therapy in patients with early-stage breast cancer, focusing on patients whose tumors have heterogeneous and low HER2 expression. Byondis will supply the investigational agent and provide regulatory and financial support for the new study arm, while Quantum Leap will provide the clinical sites and expertise.

The I-SPY 2 trial is a randomized, controlled, multicenter study with the goal of screening and identifying subgroups of women with breast cancer and evaluating which new agents are most effective for each. Additionally, the study is meant to shed light on which early indicators of response, including from imaging and tissue and blood samples, are predictors of treatment success.

The agent selected for the new investigational arm of I-SPY 2, SYD985, is what Byondis has called its "most advanced" antibody-drug conjugate. It employs Byondis' proprietary "linker-drug" technology to deliver a cytotoxin to HER2-expressing cancer cells, binding to the HER2 receptors with its monoclonal antibody. According to Byondis, SYD985 is designed with an inactivated cytotoxic payload meant to prevent early release in the bloodstream — a phenomenon that can occur with unstable antibody-drug conjugates, harming healthy tissue. The agent was developed to target multiple types of HER2-positive cancers, including breast cancer and endometrial cancer, and the company is already evaluating the drug in a Phase III study in HER2-positive, unresectable, locally advanced or metastatic breast cancer, comparing it to a physician's choice treatment. The US Food and Drug Administration previously granted the drug a fast track designation based on early-phase trial results of its activity in heavily pretreated HER2-positive metastatic breast cancer.

"We are pleased to collaborate with Quantum Leap, the FDA, and other key stakeholders to study the potential of ADC SYD985 as a neoadjuvant therapy in a wider spectrum of breast cancer tumors," Byondis CEO Marco Timmers said in a statement. "Our hope is that we can improve on current disease outcomes for cancer patients in an early stage of disease."