Pfizer's Ibrance shines in latest breast cancer study

Pfizer ($PFE) won accelerated approval of Ibrance as a first-line breast cancer treatment in February. Now it says that data in a study of the drug as a second-line treatment was so good that it stopped that study early.

Pfizer CEO Ian Read

Already pegged to reach $3 billion to $5 billion in peak sales, it is a drug that CEO Ian Read is hoping will offset some of the pain Pfizer is feeling from generic competition. Pfizer said it is in "discussions with health authorities regarding a regulatory path forward."

ISI Group analyst Mark Schoenebaum told investors today the new info will not do much to boost its sales estimates because most patients will receive Ibrance as a first-line treatment. It does, however, "add to what already appears a strong early launch," he told investors in a note today.

As a first-line treatment, Pfizer's drug is specifically indicated for women whose cancers respond to estrogen receptor but don't express human epidermal growth factor receptor 2 (HER2), and it's to be used in combination with Novartis' ($NVS) oncology drug Femara. It works by inhibiting the enzymes CDK4 and CDK6.

In the study discussed today, Ibrance was used with AstraZeneca's ($AZN) oncology drug Faslodex, a drug that Pfizer would have owned if its $118 billion bid last year for AstraZeneca had not been fought off by the U.K. drugmaker. A big part of that pursuit was to grab AstraZeneca's pipeline of immuno-oncology candidates.

Ibrance's early approval gave Pfizer its first significant success since moving on from the AstraZeneca fiasco and put Pfizer's drug out front of other CDK inhibitors being developed by competitors including Eli Lilly ($LLY) and Novartis.

Pfizer oncology CMO Mace Rothenberg

In a statement today, Pfizer's Chief Medical Officer for Oncology, Dr. Mace Rothenberg, said, "The results of this trial are especially important because they help us understand the potential of Ibrance to improve outcomes in patients with this difficult to treat cancer."

The results will also help Pfizer understand the revenue potential for the cancer drug. Its oncology meds, along with vaccines, were the two bright spots Read pointed to for 2015 earlier this year in what was an otherwise tepid sales forecast, one that came in $3 billion less than 2014 revenue. Read specifically called out Ibrance as one of the products for which he had big expectations.

- here's the announcement