I don't know who Alex To is. I generally agree with cautious approach regarding drug candidates, espeically oncology drugs. XL184 has a long way to go. However, I have to criticize some of his points:
This is not surprising at all. Traditional phase I oncology trials don't necessarily get all efficacy signals. They typically only entered a few patients in each type of cancer. I have to give EXEL credit for the RDT decision. In drug development, sometimes you have to think outside of the box. Doing one here with BMY objection was bold move from EXEL.
I really don't know where this comes from. XL184 is in more toxic cancer drug category? There is certain concern on safety for sure, but more toxic? Most patients in RDT had gone through CHEMO. As of CRPC, XL184 is going for docetaxel and/or Cabazitaxel patients at this stage. Talking about toxic, you can't get more toxic than docetaxel!