With 12 year max on Kadcyla royalties, the last couple of years of this contract in both US and ROW should, according to this GlobalData estimate, amount to some very attractive income for IMGN. If Perjeta and Kadyla each rate about 50% of the 84% share of that $7.9B market, or $3.3B. When curtains close on this deal, IMGN's worldwide royalty stream for just that last year would be ~5% of $6.6B or $.33B.
"GlobalData expects the rapid uptake of these drugs across the first-line and adjuvant settings to drive the growth of the US HER2-positive market at a strong compound annual growth rate of 12.7% to $7.9 billion by 2023, with Perjeta and Kadcyla together representing 84% of the US market."
http://formularyjournal.modernmedicine.com/formulary-journal/news/unprecedented-efficacy-latest-her
2-targeting-agents-can-extend-life-significa?page=full