By Kim Polacek, APR, CPRC - October 26, 2022
The rapid acceleration of new immunotherapies over the past decade has provided more treatment options for patients with cancer. Immunotherapy triggers the body’s own immune system to seek out and kill cancer cells. While the targeted therapies are effective, only 15% to 20% of patients have durable responses. New research suggests combining immunotherapy with other treatment modalities, such as radiotherapy, could help bolster a better response for patients. One such study for patients with metastatic, recurrent or persistent cervical cancer is being led by Moffitt Cancer Center, in collaboration with The Ohio State University Comprehensive Cancer Center.
The phase 2 study combines atezolizumab, an immune checkpoint inhibitor that works by blocking a protein that is stopping the immune system from working properly to attack cancer cells, with stereotactic body radiation therapy, which uses many precisely focused radiation beams to treat tumors. Targeted radiation is delivered to the area where all the beams intersect, shrinking the tumor while leaving the surrounding healthy tissue undamaged.
"Radiotherapy not only can shrink a tumor, but also can unmask it, making it more visible to the immune system. Therefore, it is hypothesized that utilizing immunotherapy after radiotherapy could elicit a better response."- Dr. Kamran Ahmed, Assistant Member, Radiation Oncology
“Several preclinical studies have shown a synergistic effect when radiotherapy is used in combination with immunotherapy,” said Dr. Kamran Ahmed, principal investigator of the trial and assistant member in the Radiation Oncology Department at Moffitt. “Radiotherapy not only can shrink a tumor, but also can unmask it, making it more visible to the immune system. Therefore, it is hypothesized that utilizing immunotherapy after radiotherapy could elicit a better response.”
The 13 patients enrolled in the study received stereotactic body radiation therapy first, followed by atezolizumab one week later, and every three weeks thereafter. Interim results of the study, which were presented this week at the American Society for Radiation Oncology annual meeting, showed that at a median follow-up of 18 months, progression-free survival, or length of time during and after treatment when the cancer does not get worse, was 4.5 months. Overall survival was 11 months. The study therapy was well tolerated with partial responses noted in three patients, or 23% of the study.
“The results are encouraging when you consider how difficult it can be to treat advanced cervical cancer. Participants in this trial have already seen disease progression after two or more different systemic therapies, and we did not select only PD-L1 positive tumors in this study, which is the current indication for immune checkpoint inhibitors in advanced cervical cancer,” Ahmed said. “Based on this data, we are ready to open the second stage of our study.”