Pfizer breast cancer drug combo aces trial
pharmafile | April 7, 2014 | News story | | Femera, Pfizer, breast cancer, oncology, palbociclib
New data released from Pfizer show that a combination of its investigational breast cancer drug and a treatment from Novartis helped double survival rates in certain patients.
The PALOMA-1 Phase II study was testing palbociclib in combination with the hormone therapy Femera (letrozole), developed by Novartis.
PALOMA-1 achieved its primary endpoint by significantly prolonging progression-free survival (PFS) compared with Femera alone in post-menopausal women with estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-) locally advanced or metastatic breast cancer.
For women treated with the combination of palbociclib plus Femera, the median PFS was 20.2 months, a statistically significant improvement compared to the 10.2 months of PFS in women who received Femera alone.
“These are as impressive results as I have ever seen. I do not say that lightly,” says Dennis Slamon, a UCLA physician scientist who worked with Pfizer to develop palbociclib and who owns Pfizer stock.
Results for the secondary endpoints of duration of treatment and clinical benefit rate also showed superiority in the palbociclib plus Femera arm, compared to the Femera-only arm.
Overall survival (OS) was also tested, with an OS of 37.5 months observed in the combination arm versus 33.3 months for those who received Femera alone, a difference of 4.2 months.
But researchers say that because only about 30 patients in each arm of the 165-patient trial had died, it was still too early to define the drug’s impact on overall survival. More data on OS trends will be released in the future, the firm adds.
Phoenix from the flames
The revival of this drug will be heartening to Pfizer as its course was largely abandoned in the 1990s after it failed to show consistent response against a broad range of cancers.
Since then however the understanding of cancer – notably its genetic roots – has given drugmakers new information on how these drugs, called CDK inhibitors, keep tumours from growing and metastasising.
“These data demonstrate the potential of palbociclib to be a major advance in the treatment of women with this type of advanced breast cancer,” says Dr Mace Rothenberg, chief medical officer for Pfizer Oncology.
“We are proud to be at the forefront of research and development with respect to this promising new class of investigational anticancer agents and have initiated a broad clinical development programme for palbociclib that includes breast and non-breast cancers.”
Blockbuster sales
Researchers are not the only ones excited about the data as analysts have already predicted that the medicine could generate as much as $6 billion in peak annual sales, but only if further studies are successful.
Pfizer isn’t alone in pursuing CDK drugs, which block a genetic pathway for cellular growth.
Lilly, AstraZeneca and Novartis are all testing targets among about 20 types of CDK blockers.
Just this week Lilly’s drug, called bemaciclib, stopped tumour growth for an average of 9.1 months.
About 25% of patients with hormone receptor-positive breast cancer saw their tumours shrink while more than half (55%) had them stay the same size.
Ben Adams
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