While Roche (NASDAQOTH:RHHBY) may have lost the patent battle on its HER2 therapy Herceptin in India, it won a new HER2 therapy approval for Kadycla in Europe.

Roche lost the patent for its HER2 breast cancer therapy, Herceptin, back in August when regulators struck down the patent on grounds that it was not properly submitted. Just three months later, Mylan (NASDAQ:MYL) and Biocon came out with a biosimilar, Hertraz, gaining approval in late November with the expected move to market early in the new year.

Of the $6.34 billion in 2012 that Herceptin grossed, only $21 million came from India. Roche had further cut prices of Herceptin in India by 31% this year. Nonetheless, Mylan and Biocon's Hertraz, as the first approved biosimilar, will likely capture a large part of that market. In India, revenue will be shared between Mylan and Biocon, but Mylan will retain exclusive rights in the U.S., Canada, Japan, Australia, New Zealand and EU and undoubtedly seek approvals in those regions.

This also marks the first biologic to launch for Mylan, a positive signal for the other four biologics Mylan has partnered with Biocon on.

HER2 therapies target the HER2 gene that is overexpressed in some cancers, most notably breast cancer. Roche is on its third therapy of this type, with Herceptin pioneering the class in 1988, followed by Perjeta in 2012 and now Kadcyla, which just nabbed approval in the Europe after already gaining approval in the U.S. in February and in Japan in September.

This approval, however, is limited to advanced breast cancer that has already proven refractory to Herceptin and a chemotherapeutic taxane. Roche is already looking into Kadcyla for first-line or early stage treatment against HER2-positive breast cancer, as well as HER2-positive gastric cancer.

Besides the increase in price compared to prior drugs in its class ($4,500 a month for Herceptin, $6,000 a month for Perjeta, and $9,800 a month for Kadcyla), Kadcyla paired Roche's Herceptin with ImmunoGen's (NASDAQ:IMGN) proprietary cancer-killing agent DM1.

In the agreement, Roche will retain development and commercialization rights for Kadcyla while ImmunoGen will receive royalties and milestone payments. This is fortunate for the battered ImmunoGen, which recently had to cancel trials of its in-house small-cell lung cancer drug IMGN901, resulting in a double-digit decline in share prices. Immunogen, however, is no stranger to beneficial collaborations. It struck several such collaborations this year with big pharma companies, most recently with Novartis on use of its TAP technology in exchange for royalties.

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The bottom line
While Mylan and Biocon have filled the gap for a biosimilar of Herceptin this month, this has been expected since Roche lost the IP in August -- more than a loss for Roche, it will be a gain for Mylan and Biocon. Meanwhile, the approval of Kadcyla in the EU reflects more on Roche than partner ImmunoGen. While any approval is good news, there is estimated to be around 70,000 breast cancer patients in the EU, with only one-fifth of them HER2-positive. An even smaller percentage will have already failed Herceptin and chemotherapy and thus be indicated for Kadcyla. Roche will retain the rights, and while ImmunoGen will undoubtedly benefit through royalties from the sales coming in from Europe, it still struggles to develop a therapeutic of its own. Mylan and Roche look like the biggest winners from this month's movements in HER2 therapies.

Fool contributor Amy Ho has no position in any stocks mentioned. The Motley Fool recommends ImmunoGen. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.