Patients with advanced renal cell carcinoma (RCC) who discontinued anti-PD-1/PD-L1 immunotherapy early due to unacceptable toxicity may still achieve durable responses, according to a study that will be presented at the 2017 Genitourinary Cancers Symposium.1
Current consensus guidelines recommend treating patients with metastatic RCC with nivolumab until disease progression or intolerability. Because outcomes of patients who achieve a response to therapy and then discontinue treatment due to immune-related adverse events remain unclear, researchers sought to evaluate outcomes of responders to PD-1/PD-L1 targeted therapy who discontinue immunotherapy as a result of intolerable immune-mediated toxicities.
For the study, investigators analyzed data from 19 patients with mRCC, including 8 with clear-cell histology and 1 with translocation RCC, who received an anti PD-1/PD-L1 monoclonal antibody, experienced a response, and subsequently discontinued treatment due to unacceptable toxicity. Of those, 63% received anti-PD-1/PD-L1 as monotherapy and 37% received them in combination with other systemic agents.
Treatment was discontinued for the following immune-mediated adverse events: arthritis, uveitis, arthropathy, hypophysitis, myositis, blepharitis, hepatitis, rash, pericarditis, and amylase and lipase elevations.
Results showed that 42% of patients remained progression-free following immunotherapy discontinuation and remained off any additional therapy for at least 6 months after discontinuation. Median time on immunotherapy was 5.5 months.
“In medicine, we are constantly balancing the benefits and risks of any given treatment,” lead study author Rana R. McKay, MD, assistant professor of medicine at University of California San Diego School of Medicine, said in a press release. “This is a small study, and while our findings need to be validated in a larger group of patients, it underscores that in some cases, immunotherapy can have lasting benefits even after treatment discontinuation.”
Researchers are designing a prospective clinical trial to further assess the efficacy of PD-1/PD-L1 inhibitor discontinuation in patients who experience a response to immunotherapy.
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“This study is welcome news for patients who are unable to continue immunotherapy as a result of adverse effects,” American Society of Clinical Oncology (ASCO) expert Sumanta Pal, MD, said in a statement. “It’s very reassuring to see that some patients may continue to benefit from immunotherapy even if they need to discontinue it. More broadly, these findings call into question the current standard of continuous treatment with immunotherapy, though longer term follow-up of patients is needed.”
- Some patients experience long-term tumor control even after stopping immunotherapy early [news release]. Alexandria, VA: American Society of Clinical Oncology (ASCO); February 13, 2017. Accessed February 13, 2017.