CHICAGO — Pfizer on Friday said its drug for an advanced form of lung cancer showed promising long-term results in a late-stage trial, which may help establish it as the new standard treatment for the condition.

The company’s medicine helped patients live longer without seeing their cancer progress, and most people experienced that benefit for over five years. The drug, called Lorbrena, also cut the risk of the cancer progressing in patients’ brains.

Lorbrena is already approved in the U.S. for treating adults with advanced non-small cell lung cancer who have a mutation in a gene called ALK. Only about 5% of all non-small cell lung cancer patients have the mutation, which causes cancer cells to grow and spread abnormally. 

But that translates to 72,000 people who are diagnosed with that specific form of lung cancer each year worldwide, according to a release from Pfizer. That cancer is typically aggressive and often affects younger people, the company added.

More broadly, non-small-cell lung cancer is a common form of the disease.

Lorbrena is specifically approved as a first-line treatment for that form of lung cancer, meaning patients who take it have not received any other therapy. But Pfizer’s drug isn’t currently considered the standard – or the most appropriate and widely used – treatment for the condition. 

The company thinks the new five-year data on the drug will change that. 

“In cancer medicine in general, you always want to give the best medicine upfront first. So that’s why we believe this data … will lead to [Lorbrena] becoming a standard” first-line treatment in this specific form of lung cancer, Chris Boshoff, Pfizer’s chief oncology officer, told CNBC in an interview. 

The new five-year data is from the same phase three trial that led to Lorbrena’s U.S. approval. Pfizer will present the results on Friday at the American Society of Clinical Oncology annual meeting in Chicago, the largest cancer research conference in the world. The data was also published in the Journal of Clinical Oncology.

Nearly 300 people in the trial either received Lorbrena or Pfizer’s older lung cancer drug Xalkori. At the five-year mark, 50% of patients in the trial were still receiving Lorbrena compared with 5% of people receiving Xalkori.

In the trial, Lorbrena after five years cut the risk of cancer progression or death by 81% compared with Xalkori.

Around 60% of patients treated with Lorbrena were alive without seeing their cancer progress after that same period. That compares with 8% among those who took Xalkori. 

Dr. David Spigel, chief scientific officer at the Sarah Cannon Research Institute, called those results “the best we’ve ever seen” during a briefing with reporters ahead of the ASCO conference.

“We have not seen anything close to this. Other great drugs that are available … have not reported the kind of durable, progression-free survival events of this magnitude,” Spigel said, referring to the rate of people who remained alive without seeing their cancer progress. 

He noted that there are no head-to-head trials that compare Pfizer’s Lorbrena with competing lung cancer drugs, including one called alectinib and another called brigatinib.

All three are called ALK inhibitors, which are designed to block the mutations in the ALK gene associated with abnormal cancer cell growth. Lorbrena is considered a newer, third-generation ALK inhibitor, while the two competitors are second-generation. 

But Spigel added that “it’s hard to believe” that Lorbrena would perform worse head-to-head against those drugs.

Pfizer’s other drug Xalkori is also an ALK-inhibitor, but it is no longer used in the U.S.

Lung cancers with the “ALK-positive” mutation are also especially adept at spreading to the brain. Roughly a quarter or more of patients can develop brain metastases — when cancer cells spread from their original part of the body to the brain — within the first two years of being diagnosed. 

Lorbrena slashed the risk of the cancer progressing in the brain by 94% compared with Pfizer’s old drug. Only four of the 114 patients taking Lorbrena developed brain metastases within about 16 months, compared with 39 out of the 109 taking Xalkori.

Lorbrena is effective at preventing and treating brain metastasis because it can cross a membrane called the blood-brain barrier and enter the brain, something not all drugs can do.

Spigel called that another “impressive finding” since progression in the brain is “quite awful for patients and something we try desperately to prevent or treat.” 

No new safety issues were reported for Lorbrena. The most common side effects included swelling, weight gain, cognition and mood changes and high cholesterol in the blood, among others.

But Spigel called the cognitive issues associated with Lorbrena “unusual” since it is not seen with its competitors.

In a note on Thursday ahead of the data release, Leerink Partners analyst Dr. Andrew Berens said he believes Lorbrena’s central nervous system side effects are partly why it is often used as a second rather than first-line treatment for this advanced form of lung cancer. Those changes to cognition and mood result “in a lower patient quality of life,” he said.

But Pfizer’s Boshoff said once physicians use Lorbrena for the first time, they become comfortable managing any specific side effects associated with the drug.

He noted that educating physicians about how to manage adverse effects will be an important part of Lorbrena’s “relaunch” following the release of the new data.