Found out why Teva couldn't manufacture on their own - a cGMP issue with its Irvine, CA facility. They had to partner so they can at least enjoy some of the exclusivity period.
Moreover, since asking the question in #msg-59214635, I learned that Abraxis BioScience (APP Pharma’s ancestor) had done contract work for LLY on Gemzar.
“The efficient-market hypothesis may be the foremost piece of B.S. ever promulgated in any area of human knowledge!”