Synthon’s SYD985 ADC demonstrates anti-tumor activity, outperforms leading anti-HER2 ADC

Synthon Biopharmaceuticals today announced the results of a head-to-head comparative program of its antibody-drug conjugate (ADC) SYD985 with Roche's market leading anti-HER2 ADC, T-DM1 ( Kadcyla^®*).

SYD985 is a HER2-targeting ADC based on trastuzumab and Synthon's proprietary cleavable linker-duocarmycin (vc-seco-DUBA) payload. Data support the potential of SYD985 to address the high unmet medical need of patients with HER2 2+ and HER2 1+ breast cancer for whom there is currently no effective therapy available.

Comparisons were drawn in in vitro and in vivo testing. The in vivo study was conducted in patient-derived xenograft models in mice - preclinical models known for their highly predictive value for clinical outcome. In the study, which involved breast cancer models, SYD985 demonstrated unprecedented anti-tumor activity and clearly outperformed T-DM1, particularly where there was a low expression of HER2. See further information in the Notes to Editors.

More in-depth analyses and preclinical data on this benchmark study with SYD985 will be presented at the AACR Annual Meeting 2014.

Based on these findings, the preclinical profile of SYD985 may enable the extension of the target population of cancer patients who may respond to this treatment to include FISH-negative / IHC-HER2 1+ and 2+ patients. Analogous to T-DM1, SYD985 will be tested in refractory breast cancer patients who are FISH-positive and/or IHC-HER2 3+, but these recent data also warrant clinical studies with SYD985 in patients with HER2 1+ and 2+ malignancies.

Jacques Lemmens, chief executive officer of Synthon comments: "We are very pleased with these results. When confirmed in clinical studies, the target population for SYD985 would be significantly broader than that for the current therapy option. This would enable a possible treatment for cancer patients with a high unmet medical need, including triple negative breast cancer patients, where presently there is none."

Synthon is preparing for the 'first-in-human study which is planned to start in the second half of 2014. The company believes this Phase I clinical trial will further validate its ADC technology as potentially best-in-class.