Scholarly Spotlight: Stopping Immunotherapy Too Soon May Raise Risk in Merkel Cell Carcinoma
In a new eight-year study of patients with advanced Merkel cell carcinoma (MCC), researchers from the University of Washington, Fred Hutch Cancer Center, and Stanford University found that stopping immune checkpoint inhibitor (ICI) therapy is associated with a higher risk of disease progression — 39% at two years compared with 14% among those who continued treatment.
The risk was greatest in patients with partial responses or those who discontinued early due to toxicity, while elective discontinuation after more than a year of complete response appeared relatively safe. These results underscore the need for cautious, individualized decisions about ICI treatment duration.
The study, “Risk of disease progression after discontinuing immunotherapy in 105 patients with Merkel cell carcinoma who responded to PD-1 pathway blockade,” was published in the Journal for ImmunoTherapy of Cancer on July 21, 2025.
Led by Lisa Tachiki, MD, Assistant Professor in the UW Division of Hematology and Oncology and physician researcher at the Fred Hutch Clinical Research Division, the project also involved researchers from Stanford, the laboratory of Paul Nghiem, MD, PhD, and the Merkel Cell Carcinoma (MC3) Institute.
Their findings offer important guidance for tailoring immune checkpoint inhibitor duration, helping to balance treatment benefits with risks in this aggressive skin cancer.
Please join us in extending our congratulations to these authors on this impactful study!
Dr. Tachiki highlights the study's findings and its impact on the treatment of MCC.
What are the main findings of this publication, and why are they important?
This study found that people with advanced Merkel cell carcinoma who stopped immunotherapy were more likely to have their cancer come back compared to those who stayed on treatment. This is important because it shows that stopping too soon may put some patients at higher risk, particularly with patients whose tumors have only partially shrunk with immunotherapy treatment.
How will this study impact the treatment of MCC going forward?
The study suggests that doctors should be very cautious about stopping immunotherapy too early. For patients whose cancer completely disappears and who have been on treatment for at least a year, a carefully planned treatment discontinuation may be reasonable. But for others, especially those whose cancer only partially responded, continuing therapy is likely safer.
Going forward, this evidence may encourage doctors, patients, and insurers to rethink the “two-year stopping point” with immunotherapy treatment and instead base decisions on individual response and risk.
What are the next steps for this research, or what follow-up questions are you hoping to answer?
The next steps are to figure out better ways to balance long-term treatment with side effects, costs, and quality of life. We are especially interested in whether giving immunotherapy less often (for example, every few months instead of every few weeks) might keep the cancer under control while reducing the burden on patients.
At the same time, it would be important to have better tools, such as using advanced scans or blood tests like circulating tumor DNA, to identify which patients can safely stop treatment altogether. We also hope to combine our data with results from other Merkel cell cancer centers around the world, so that together we can build a clearer picture of long-term outcomes and guide care with more confidence.
