Not sure if any of you have been following the trials and tribulations of the SLXP/PGNX Relistor CRL. This week, SLXP provided color to the CRL. The FDA is greatly concerned about CV risk in mu-opioid antagonists. Remember Entereg? There are a total of three mu-opioid antagonists for OIC in Phase III, with different approaches to long term safety. All are one year studies.
1. SLXP ran a 1040 patient single arm study. Relistor was administered as needed, minimum once per week. The FDA didn't accept this.
2. AZN is running an 840 patient study, randomized 2:1 naloxegol vs. TPC. Naloxegol is dosed daily.
3. CBST (CB-5945) is running a 1400 patient randomized double blind safety study with daily dosing.
The main FDA objections to the SLXP study aren't clear. It could be that it is single arm, or open label, non-daily dosing or not enough patients, or all four combined. NKTR stock got whupped on this news.