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Sophiris Bio has announced that the first patient has been dosed in its phase 2b study to evaluate the safety and tolerability of topsalysin in focally treating men with clinically significant localized prostate cancer. Topsalysin (PRX302) is an innovative, first-in-class pore-forming protein engineered to be activated only in the presence of enzymatically-active PSA, which is only found within the prostate.
This phase 2b study will build on the successful phase 2a proof-of-concept study for the treatment of localized prostate cancer which demonstrated that a targeted intraprostatic administration of topsalysin has the potential to safely ablate prostate tumor cells.
"Topsalysin has the potential to provide a much-needed opportunity to treat the patients who have clinically significant localized prostate cancer in a targeted focal manner, ablate pre-identified lesions and downgrade the patient to non-significant cancer," said Dr. Hashim Ahmed, professor and chair of urology, Imperial College London. "This would be extremely exciting and clinically meaningful for men, as it could help them either avoid or delay the need for radical therapies and significant side effects associated with radical therapy."
"We have the potential to provide an efficacious, less invasive treatment option for patients with clinically significant localized prostate cancer," said Randall E. Woods, president and chief executive officer of Sophiris Bio. "Our goal with this international Phase 2b clinical study is to confirm the dose and optimize the delivery of topsalysin and to evaluate the safety and efficacy of a second dose of topsalysin in a clinical setting."
The study is a multi-center, open-label, Phase 2b study evaluating the safety and efficacy of targeted intraprostatic administration of topsalysin for the treatment of histologically proven, clinically significant, localized prostate cancer. Approximately 40 patients will be enrolled in the study at multiple sites in the United States and the United Kingdom. The study will utilize previously obtained MRI images of each patient's prostate mapped to real time 3D ultrasound to target the delivery of topsalysin directly into and around a pre-identified clinically significant tumor. Safety and tolerability will be assessed post-treatment over 26 weeks. Efficacy will be assessed by biopsy and imaging (mpMRI) at 24 weeks. The Company expects to receive six month biopsy data for all patients in the first quarter of 2018 assuming enrollment is completed as expected.
Importantly, the Phase 2b study includes an option to re-treat patients with a second dose of topsalysin, with a targeted biopsy to occur six months following the second dose. In order to be eligible for a second dose, the patient cannot have experienced a significant adverse event attributable to topsalysin or the dosing procedure from the first dose and the patient will need to have had a clinical response from the first dose but still have the presence of a clinically significant lesion area. The Company expects to have final biopsy data on all patients who receive a second dose in the fourth quarter of 2018.
Sophiris bio, sphs, treat prostate cancer
