According to the NKTR-102 poster from the Phase II single arm study, the preliminary estimate for median survival was 10.3 months from all patients/protocols. Remember that treatment doesn't end for patients in the Phase II when they progress, they move on to other drugs (like they are in the Phase III).
The Eribulin Phase III results, quoting from the paper, were as follows...
"762 women were randomly allocated to treatment groups (508 eribulin, 254 TPC). Overall survival was significantly improved in women assigned to eribulin (median 13·1 months, 95% CI 11·8-14·3) compared with TPC (10·6 months, 9·3-12·5; hazard ratio 0·81, 95% CI 0·66-0·99; p=0·041)."
I believe the two month number was chosen because a lesser survival is not likely to be statistically significant. Also, look at the range of survivals from the different TPC drugs, 9.3 to 12.5 months. You can bet that doctors have refined their skill at selecting third line drugs since the Eribulin study. Dr. Perez believes she can beat TPC including Eribulin by two months? My skepticism isn't based on an unfounded guess, it is based on formally released data.
How in the world did Dr. Perez conclude that NKTR-102 is likely to extend OS by two months over the physician selected best available treatment? It certainly can't be based on the single arm Phase II results, can it? I'm thinking the best NKTR could realistically hope for is non-inferiority with a superior side effect profile.