Leerink says that after close examination, the data in Puma Biotechnology's ASCO abstract for neratinib's adjuvant study ExteNET look strong. The firm notes that unlike the HERA trial for Herceptin which enrolled only centrally confirmed HER2-positive breast cancer patients, approximately 80% of Puma's ExteNET patients were confirmed to be HER2+ upon central testing. When focusing on these patients, the magnitude of benefit for neratinib improved, Leerink says. It estimates disease free survival including ductal carcinoma in situ difference at two years to be 4.5%. The firm keeps an Outperform rating on Puma amid today's selloff.