Byondis ready to link up to bring Herceptin-booster to market after phase 3 win

A linker drug from Byondis that boosts the targeting power of Roche's Herceptin helped patients with a certain type of advanced breast cancer live longer without disease progression in a phase 3 clinical trial.  

The Dutch biopharma is now ready to consider linking up with a partner to bring the therapy to market. 

Byondis said Tuesday that trastuzumab duocarmazine, or SYD985, showed a statistically significant improvement over a physician's choice of treatments in the late-stage Tulip trail. Patients in the study had pretreated HER2-positive unresectable locally advanced or metastatic breast cancer.

SYD985 contains the monoclonal antibody Herceptin and an investigational cleavable linker-drug, which helps boost the success of antibody-drug conjugate therapies by hacking the tumor cells to selectively release the toxin in the therapy. They also remain stable in blood for a long time, allowing the medicine to get to where it needs to go.

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Byondis has developed its own linker-drug technology as a form of targeted chemotherapy. SYD985 received fast-track designation from the FDA in January 2018. Byondis is hoping to move quickly with a regulatory filing by the end of this year after revealing the results of the 436-patient study, according to a statement.

Detailed results from the study were not disclosed. Byondis plans to publish more information at upcoming conferences, the company said. Chief Medical Officer Jan Schellens, M.D., Ph.D., described the top-line results as a “promising potential clinical advance.”

Byondis is trying to slip into a tight market of Big Pharma peers that have dominated breast cancer treatment in recent decades. In the physicians' choice trial, SYD985 was up against GlaxoSmithKline’s Tykerb, Genentech’s Xeloda, Eisai’s Halaven, Herceptin and the chemotherapy Navelbine.

The study enrolled patients who experienced progression during or after two or more HER2-targeting treatments previously and patients who in the past exhibited progression during or after treatment with Roche’s Kadcyla.

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The Swiss pharmaceutical company's HER2 antibody-drug conjugate, approved by the FDA in May 2019, raked in $900 million in the U.S. and $1.94 billion worldwide in 2020 sales (PDF).

With the new results in hand, Byondis is now in the planning stages of inking partnerships with pharmaceutical companies to commercialize the lead drug, which targets the world’s most common cancer. 

SYD985 is also being trialed in four other studies: a phase 2 clinical trial looking at HER-2 expressing endometrial cancer and a phase 1 study of the effects of the drug combined with GlaxoSmithKline's Zejula in patients with HER2-expressing metastatic solid tumors as well as two Quantum Leap Health Collaborative trials. 

Byondis rebranded from Synthon Biopharmaceuticals in April 2020.