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OncoGenex Pharmaceuticals, Inc. Message Board

  • pieblaze pieblaze May 20, 2009 10:41 PM Flag

    Is the P Value statistically relevant ?

    "Mature Phase 2 data indicates a p- value of .70 for overall survival and a P value of .40 for Metastases, for all you statisticians out there please clarify if this overall "survival" p-value of .70 is statistically significant ( always considered .50 the cut off) or will this be clarified at ASCO meeting on 30th. If I am misinterpreting the data, please have someone who knows give us a comment.

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    • Raw data was HR=0.60 with p=0.07 which is pretty impressive considering the sample size. Phase 2 oncology studies are rarely powered for survival, and this one was no exception. Most recent pivotal prostate cancer trials enrolled ~500 patients per trial (DNDN, CEGE) with survival as a primary endpoint.
      The notion of P=0.05 demonstrating statistical significance or not is meaningless for a phase 2. Statistically speaking it's an arbitrary number. However, FDA generally requires 2 independent studies demonstrating a P<0.05 for approval.

      What we learn from the phase 2 OGXI study is that the probability of hitting p<0.05 with a a better powered (i.e. with a larger sample size) phase 3 is very high. Further, what is impressive with this dataset is that the PROSPECTIVELY defined multivariate analysis accounting for prognostic factors demonstrated HR=0.54 with a P=0.04. i.e. if you account for certain 'imbalances' in the trial's arms, you see better seperation between the study arms.

      To make a long story short - OGXI has excellent probability of replicating the survival benefit observed in a future, better powered study. And more importantly, it's likely to be a highly partenable asset for a pharma company. I wouldn't be surprised to see a minimum $50 million ufront deal for the rights of this drug excluding future milestones before year-end. That alone would translate to >$10/share of cash for OGXI stock.

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