The Food and Drug Administration on Thursday approved an innovative new treatment for patients with a form of lung cancer. It should only be used by patients who have exhausted all other options for treating small cell lung cancer and who have a life expectancy of four to five months.
The drug tarlatamab, or Imdelltra, produced by the Amgen company, tripled the life expectancy of patients, guaranteeing them an average survival of 14 months after taking the drug. Forty percent of those who received the drug responded.
After decades without real progress in treatments for small cell lung cancer, tarlatamab offers the first real hope, said Dr. Anish Thomas, a lung cancer specialist at the federal National Cancer Institute who was not involved in the study.
“I feel like it's a light after a long time,” he added.
Dr. Timothy Burns, a lung cancer specialist at the University of Pittsburgh, said the drug “will change clinical practice.”
(Dr. Burns was not an investigator on the study but served on an Amgen advisory board for a different drug.)
The drug, however, has a side effect that can be serious: cytokine release syndrome. It is an overreaction of the immune system that can cause symptoms such as skin rashes, rapid heartbeat and low blood pressure.
Each year, approximately 35,000 Americans are diagnosed with small cell lung cancer, and the prognosis is poor. The cancer has usually spread beyond the lung by the time it is detected.
The standard treatment is old-fashioned chemotherapy – unchanged for decades – combined with immunotherapies that increase patients' lifespan by about two months. But, almost inevitably, cancer resists treatment.
“95% of the time it will recur, often within a few months,” Dr. Burns said. And when it recurs, he added, patients find it more difficult to tolerate chemotherapy, and the chemotherapy is even less effective.
Most patients live only 8 to 13 months after diagnosis, despite undergoing chemotherapy and immunotherapy. The group of patients participating in the clinical trial had already undergone two or even three cycles of chemotherapy, which is why their life expectancy without the drug was so short.
The poor prognosis for small cell lung cancer stands in stark contrast to the situation of the other, more common non-small cell lung cancer, which has been a triumph of the revolution in cancer treatments. New targeted therapies search for the molecules that tumors need to grow, containing their spread.
As a result, Dr. Thomas said, many patients with this form of lung cancer live so long that their disease becomes “almost like a chronic disease.”
There were several reasons why small cell lung cancer patients were left behind.
One is the type of genetic mutation that cancer relies on to grow.
Dr. Jay Bradner, Amgen's chief scientific officer, explained that other cancers are caused by aberrant genes that are turned on. Treatment involves drugs to turn off these genes.
But small cell lung cancer is driven by disabled genes, making them difficult to target, Dr. Bradner explained. Another reason is cancer's ability to block immune system cells that try to destroy it.
Tarlatamab is an antibody built to overcome these obstacles. It has two arms, the first of which attaches to the growth-promoting molecule that stands like a flag on the surface of tumor cells. It serves as an identifying label for the drug, allowing tarlatamab to find cancer cells. The other arm grabs a T cell floating in the bloodstream. The T cell, a white blood cell, can kill tumors if it can get close to them.
The drug brings the T cell and tumor cell together, poking holes in the cancer or activating genes that make it self-destructive.
Patients involved in the clinical study say they have regained their lives.
Martha Warren, 65, of Westerly, RI, discovered last year that she had small cell lung cancer. She joined Facebook groups and quickly saw the bad news: Most patients don't live long. Her best hope, she decided, was a clinical trial. After chemotherapy and immunotherapy, with the cancer growing rapidly, she was accepted into the Amgen study and she began going to Yale for infusions of the drug.
Almost immediately his cancer began to shrink dramatically.
“I feel as normal as I did before I had cancer,” Ms. Warren said. “There's a lot of hope with this drug,” she added.
The Amgen study, and the approval, however, involved patients like Ms. Warren who had already undergone a couple of cycles of treatment. Could Tarlatamab help sooner?
Amgen is starting such a study now, testing the drug immediately after initial chemotherapy.