The approval is for patients with stage 3 NSCLC whose disease has not progressed following platinum-based chemoradiation therapy. Imfinzi is now the only immunotherapy approved in Canada for this indication.
“Health Canada’s approval of Imfinzi heralds a new era in the treatment of stage III, unresectable lung cancer. Despite its often deadly prognosis, we attempt to treat these patients with the intent to cure their disease. We have been long awaiting a new therapeutic option that can offer some hope post-chemoradiation therapy. With Imfinzi, we now have a proven, approved treatment that may significantly improve outcomes for patients within this disease setting,” Rosalyn Juergens, MD, PhD, medical oncologist at Juravinski Cancer Centre, said in a press release.
Imfinzi is a fully human monoclonal antibody designed to counter the tumor’s immune-evading tactics and release the inhibition of immune responses.
The approval was based on data from the randomized, multicenter Phase 3 PACIFIC clinical trial (NCT02125461), in which Imfinzi extended the time to disease worsening or death by nearly one year (11.2 months) against placebo.
This represented a 48% reduction in the risk of progression or death versus placebo in all patients, regardless of their programmed death-ligand 1 (PD-L1) status. PD-L1 is a protein found on the surface of cancer cells. When it binds to its receptor, PD-1, on T-cells, it makes it difficult for these immune cells to find and destroy cancer cells. PD-L1 levels can be used to predict a patient’s response to medications designed to block this interaction like Imfinzi.
Patients with stage 3 NSCLC are typically treated with a combination of surgery, radiation therapy, and/or chemotherapy. However, despite treatment, most NSCLC patients’ cancer ends up spreading to other parts of their bodies. Over the past two decades, researchers have tried to improve outcomes for these patients. Trial results show that Imfinzi may be able to do just that.
Additionally, the incidence and severity of adverse events were comparable with those of patients receiving placebo, with the most common events being cough, pneumonitis, upper respiratory tract infections, and rash.
About 8% of patients receiving Imfinzi had to discontinue their participation in the trial due to adverse reactions after concurrent chemoradiation therapy.
“The progression-free survival rates seen with Imfinzi are unprecedented in their impact in this disease setting where there have been no other beneficial treatments to offer patients in the last two decades,” said Rob El-Maraghi, MD, medical oncologist at the Simcoe Muskoka Regional Cancer Centre.
The ongoing PACIFIC study is still evaluating overall survival, but detailed interim results are already available in the New England Journal of Medicine, under the title “Durvalumab after Chemoradiotherapy in Stage III Non–Small-Cell Lung Cancer.”
Stage 3 NSCLC represents about 35% of all new NSCLC diagnoses, with nearly 80% of patients unsuited for surgery.
Other clinical trials currently studying Imfinzi in NSCLC patients include the Phase 3 MYSTIC (NCT02453282), the Phase 3 NEPTUNE (NCT02542293), the Phase 2 PEARL (NCT02994576) and the Phase 3 POSEIDON (NCT03164616) studies. Both PEARL and POSEIDON are currently recruiting participants.
In February , the U.S. Food and Drug Administration approved Imfinzi as the first immunotherapy in the United States for patients with advanced NSCLC who have not progressed after chemoradiation therapy.