In a new clinical study from Washington University in St. Louis, researchers found that the new drug sotorasib reduces tumor size and shows promise in improving survival among patients with lung tumors caused by a specific DNA mutation
The drug is designed to shut down the effects of the mutation, which is found in about 13% of patients with lung adenocarcinoma, a common type of non-small-cell lung cancer.
The Food and Drug Administration approved sotorasib May 28 as a targeted therapy for patients with non-small-cell lung cancer whose tumors express a specific mutation—called G12C—in the KRAS gene and who have undergone at least one previous therapy for their cancer.
Non-small-cell lung cancer makes up over 80% of all lung cancers. More than 200,000 new cases of non-small-cell lung cancer are diagnosed annually in the United States.
Sotorasib, also known by the brand name Lumakras, is made by Amgen, which funded the trial.
In the study, the team tested 126 patients with non-small-cell lung cancer that had a specific mutation in the KRAS gene.
A single DNA error swaps out an important protein building block, placing a cysteine where a glycine should be. Tumors with the mutation manufacture a version of the KRAS protein that is almost constantly active, driving tumor growth.
Sotorasib, taken daily by mouth, blocks tumor growth by trapping the KRAS protein in its inactive form.
To evaluate this new therapy, all patients enrolled in the study were treated with sotorasib; phase 2 trials evaluating safety and effectiveness often do not include a placebo group.
The team found the drug caused at least some tumor shrinkage in 102 out of 126 patients (82%). About 37% of the patients’ tumors reduced in size at least 30%.
In contrast, response rates to standard therapy in these patients range from 6% to 20%.
Forty-two patients’ tumors (34%) showed a partial response to the therapy, meaning the tumor shrank substantially and its growth was controlled for a period of time; and four patients (3%) showed a complete response that left no evidence of disease.
For tumors that shrank, the tumor size was reduced by about 60%, on average.
The effects of sotorasib lasted an average of 11 months, and the drug also showed progression-free survival—meaning the tumor did not continue growing during this time—of almost seven months.
In contrast, patients with this lung cancer who receive standard therapy have an average progression-free survival of two to four months. The average overall survival for all patients in the trial was 12 ½ months.
About 7% of patients stopped sotorasib treatment because of severe side effects, but no side effects were life-threatening, and no patient died as a result of the treatment.
The researchers are hopeful that this approach will be a new option for patients with lung cancer driven by this specific type of KRAS gene alteration.
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The study is published in The New England Journal of Medicine. One author of the study is Ramaswamy Govindan, MD.
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