MERSANA THERAPEUTICS, INC. (MRSN)

[jaybe]

I would add here if I hadn't loaded up on ADXS last week.

I trust Ana to handle this carefully and professionally and to resolve the hold in less than a month. I assume they are already on dose level 9, since ASCO data cut in May nearly completed DL7 and its a 4-week cycle to assess DLT prior to moving to next dose. Dose level 7 patients have been on drug for three months, with one DLT and one Grade 3 event, AST elevation (reported at ASCO). So far about ~50 patients have been dosed with this payload, including 1522 & 1536, and this is the first Grade 4 or 5 event. All patients are very sick, with average of 4 prior regimens.

Definitely a risk-raising event, but given the established MOA and safety reported to date, I think this will turn out to be a monitorable and manageable event for investigators. Of course this is not good news, but likely outcome will force early reporting of additional safety data around time of Q2 call, pencilled for August 10th.