Researchers have developed a model to predict overall survival for people with advanced urothelial cancers treated with the immune checkpoint inhibitor atezolizumab.
The model, which is based on six clinical factors, may help inform treatment decisions for use of atezolizumab in these patients.
These findings will be presented at the upcoming 2018 Genitourinary Cancers Symposium in San Francisco, California.
“In just the past few years, the U.S. Food and Drug Administration has approved five new immunotherapies for urothelial cancers,” said lead study author Gregory Pond, PhD, associate professor, McMaster University, Hamilton, Ontario, Canada.
“Based on the rapid availability of new therapies, we thought it was important to try to assess which patients might benefit the most from atezolizumab, which is one type of these new therapies. We believe we’ve developed the first prognostic model that, once confirmed in larger studies, could provide a critical decision-making tool for clinicians.”
About the Study
Urothelial cancers typically occur in the urinary system, and bladder cancers account for the majority of urothelial cancers; other types include ureter and renal pelvis cancers.
An estimated 81,190 new diagnoses of bladder cancer will occur in the United States in 2018, and there will be an estimated 17,240 deaths.
In 2017, bladder cancer was the sixth most commonly diagnosed cancer in the United States.
To develop the model, the researchers analysed data from two clinical trials of PD-L1 inhibitor atezolizumab in people with advanced urothelial cancer that worsened despite cisplatin chemotherapy, which is the standard treatment for this disease.
The model was developed based on data from 310 people enrolled in the phase II IMvigor210 trial, and then validated based on data from a phase I trial of 95 people with bladder cancer (PCD4989g).
Researchers considered various clinical factors that had been previously shown to predict survival in patients with advanced bladder cancer receiving chemotherapy, including performance status (a measure of patient’s ability to perform activities of daily living), the site of the primary tumour and sites of metastases, stage at diagnosis, various blood test results, smoking status, and prior therapies. In addition, they assessed PD-L1 status of immune cells, which is a marker for efficacy of atezolizumab.
The six factors that were ultimately included in the optimal prognostic model for overall survival were:
The researchers found that patient survival was associated with the number of prognostic factors a patient had.
In the Imvigor210 trial, the median overall survival was 19.6 months for those with 0-1 factors, 5.9 months for those with 2-3 factors, and 2.6 months for those with 4 factors or more.
“While other factors also affect overall survival, no others were observed to be statistically significant in this dataset," said Dr. Pond.
"That is also why further validation of this model is required, as we will need to check if the factors identified in this model are consistent across different datasets.”
The authors also hope to do some subgroup analyses to determine if people with specific characteristics may benefit more from atezolizumab immunotherapy than others.
More research is also needed to determine if this prognostic model could be applied to other patient populations or other immunotherapies.