On January 26, 2024 Orion reported at the 2024 ASCO (Free ASCO Whitepaper) GU Cancers Symposium a poster with additional data from the ongoing Phase II CYPIDES trial evaluating the safety and efficacy of ODM-208 (or MK-5684), an investigational, oral CYP11A1 inhibitor, in heavily pretreated patients with metastatic castration-resistant prostate cancer (mCRPC) with and without AR-LBD mutations (Press release, Orion, JAN 26, 2024, View Source [SID1234639560]). Previously published data has focused on patients with androgen receptor gene (AR) ligand-binding-domain (LBD) mutations. The new data reports initial results in an extension cohort of mainly AR-LBD wild-type patients combined with previously reported phase 2 data (AR-LBD mutation-positive only).
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Prostate cancer continues to be regulated by steroid hormones, even in castration-resistant disease. Data from the Phase II CYPIDES trial suggest that ODM-208/MK-5684 potently inhibits all steroid-hormone biosynthesis with observed antitumor activity in a heavily pretreated mCRPC population, especially in patients with AR-LBD mutations.
In Phase II CYPIDES, at data cut-off, a total of 134 previously treated mCRPC patients received 5mg of ODM-208/MK-5684 twice a day with glucocorticoid/mineralocorticoid replacement and ongoing androgen-deprivation therapy. Of the total, 66 patients had AR-LBD mutation and 68 were AR-LBD wild-type. PSA (prostate-specific antigen) responses occurred in men without AR-LBD mutations, but were more frequent in those with such mutations. A decrease in PSA levels of 50% or more occurred in 55.6% of patients with AR- LBD mutation and in 16.7% of AR-wild-type patients. A decrease in PSA levels of 30% or more occurred in 69.8% of patients with AR-LBD mutation and in 30.0% of AR-wild-type patients. Results on other endpoints are not yet mature and will be reported later. Adverse events on ODM-208/MK-5684 were clinically manageable and the rate of serious adrenal insufficiency remained low on hormone replacement therapy (3.0%), although many patients continue on treatment and further events are possible. The new data support and are consistent with the previously reported results.
"These results support the continued importance of hormone-based treatments and potential of ODM-208/MK-5684 as a new inhibitor of AR driven growth of prostate cancer, even in heavily treated patients with advanced disease. Interestingly, the results in the patients with AR-wild-type suggest that they benefit from ODM-208/MK-5684 too, although the PSA decrease was more frequently seen in the patients with AR-LBD mutation. We look forward to having further data both in AR LBD positive and negative patients in the on-going Ph3 studies", said Professor, M.D., Ph.D. Outi Vaarala, Senior Vice President of Innovative Medicines and Research and Development at Orion.
About ODM-208/MK-5684
ODM-208/MK-5684 is an investigational oral, non-steroidal and selective inhibitor of the CYP11A1 enzyme discovered and developed by Orion for the treatment of hormone-dependent cancers, such as prostate cancer. ODM-208/MK-5684 is being developed through a collaboration with MSD (tradename of Merck & Co., Inc. Rahway NJ USA). The compound is being evaluated in two pivotal Phase 3 clinical trials in combination with hormone replacement therapy (HRT), for the treatment of certain patients with metastatic castration-resistant prostate cancer (mCRPC). Patients are now enrolling in the trials, named OMAHA1 (NCT06136624) and OMAHA2a (NCT06136650).