The drug, called crizotinib, would be the first targeted treatment for the roughly 50,000 people who get this cancer each year worldwide. It might eventually produce annual revenue for Pfizer exceeding $2 billion.
The first overall survival data for patients with advanced non-small cell lung cancer treated with the drug, called crizotinib, showed 74 percent were still alive after a year and 54 percent after two years, researchers announced at a huge cancer specialists conference.
Median overall survival, a key measure, hasn't been determined because more than half the 82 patients are still alive.
The early-phase study did not include a direct comparison group. But among similar patients getting standard cancer drugs in other research, 44 percent survived for a year and just 12 percent were alive after two years, said lead researcher Dr. Alice Shaw.
Crizotinib, part of the new wave of personalized medicine in which drugs are being matched to patients according to genetics, would be the first drug in a new class called ALK inhibitors.
The twice-a-day pill targets the roughly 4 percent of non-small cell lung cancer patients whose tumors have a genetic rearrangement of an enzyme that stimulates growth and survival of those cancer cells.
The experimental drug works by turning off that enzyme, with a rapid and dramatic effect that's long-lasting, said Shaw, a thoracic oncologist at Massachusetts General Hospital Cancer Center.
"This is not a cure for this type of patients. Unfortunately, ... cancer becomes resistant over time," Shaw added, so researchers already are trying to develop new treatments that could push this cancer back into remission.
In a continuation of that study, also sponsored by Pfizer, researchers found that among 119 patients whose cancer had worsened after three or more prior types of treatment, 88 percent had their tumors shrink at least somewhat over nearly a year follow-up.
Similarly, in a midstage study of 136 patients who failed at least one previous cancer treatment, 54 percent had their tumors shrink by about a third or more and 83 percent had tumors shrink somewhat. Most patients had mild side effects, but two of the nine patient deaths during that study were considered treatment-related.
U.S. regulators are expediting their review of crizotinib, indicating its promise. Pfizer expects it to be approved in the U.S. by year's end, because under the "Fast Track designation" the Food and Drug Administration gave the drug last December, Pfizer was able to start submitting batches of data in January, rather than wait until all studies are completed.
Two larger, late-stage studies comparing crizotinib directly to standard treatments are continuing, one in patients for whom prior drugs didn't work and one in new patients. There are no treatments specifically for patients with this type of lung cancer, although some others are in much earlier stages of testing.
So the FDA is expected to conditionally approve crizotinib based on results of the earlier studies rather than wait until the latest ones are completed, said Dr. Robert Sweetman, head of medical affairs for Pfizer's cancer unit.
Analysts also think the drug is likely to get approved.
"I think crizotinib is one of the most important ... near-term products for Pfizer," said Morningstar analyst Damien Conover. "It gives a really important new therapy to a lot of patients that don't have very many options."
About 85 percent of lung cancer cases are non-small cell lung cancer. Roughly three-fourths aren't diagnosed until tumors have spread, and only 6 percent of those patients live five years.
Conover predicts crizotinib will build to peak sales of about $2.5 billion in about a decade. Credit Suisse analyst Catherine Arnold is forecasting it will bring in $600 million a year by 2015.
Pfizer, based in New York, also was presenting studies on its other experimental cancer drugs at the American Society of Clinical Oncology conference, which began Friday.
Those include two studies of axitinib for advanced kidney cancer and three of bosutinib for chronic myeloid leukemia, plus studies of two approved Pfizer cancer drugs, Sutent and Torisel, for new uses.