Image source: PublicDomainPictures.net.When it comes to Celgene (NASDAQ: CELG), investors' focus has revolved around its megablockbuster Revlimid franchise -- and for good reason. Revlimid, an oral treatment for blood cancer indicated for use in first- and second-line multiple myeloma, brought in $5.8 billion in revenue and accounted for 63% of Celgene's total sales in 2015.