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Efficacy of Immune Checkpoint Inhibitors in Rare Tumours: A Systematic Review
Fausto Petrelli1, Francesca Consoli2, Antonio Ghidini3
1Oncology Unit, Azienda Socio Sanitaria Territoriale (ASST) Bergamo Ovest, Treviglio, Italy.
Background:
Rare cancers, as defined by the European Union, occur in fewer than 15 out of 100,000 people each year. The International Rare Cancer Consortium defines rare cancer incidence as less than six per 100,000 per year. There is a growing number of reports of the efficacy of immune checkpoint inhibitor (ICI) therapy in patients with rare tumours, and hence, we conducted a comprehensive review to summarise and analyse the available literature.
Methods:
A literature search of PubMed was performed on January 31, 2021, using the following ICI names as keywords: ipilimumab, tremelimumab, cemiplimab, nivolumab, pembrolizumab, avelumab, atezolizumab, and durvalumab. Studies on patients with rare tumours who were being treated with ICIs were included. We plotted the overall response rate against the corresponding median survival across a variety of cancer types using linear regression.
Results:
From 1,255 publications retrieved during the primary search, 62 publications were selected (with a total of 4,620 patients). Only four were randomised trials. A minority were first-line studies, while the remaining were studies in which ICIs were delivered as salvage therapy in pretreated patients. There was a good correlation between response rate and overall survival (Spearman R2 >0.9) in skin cancers, mesothelioma, and sarcomas.
Conclusions:
Treatment of advanced-stage rare tumours with ICI therapy was found to be associated with significant activity in some orphan diseases (e.g., Merkel cell carcinoma) and hepatocellular carcinoma. Several ongoing prospective clinical trials will expand the knowledge on the safety and efficacy of ICI therapy in patients with these rare cancers.
Insights
Immune checkpoint inhibitors (ICIs) show significant activity in rare cancers like Merkel cell carcinoma and hepatocellular carcinoma. Further trials are ongoing to confirm their safety and efficacy in these uncommon diseases.
Area of Science:
- Oncology
- Immunotherapy
Background:
- Rare cancers affect fewer than 15 in 100,000 people annually.
- Growing evidence suggests immune checkpoint inhibitors (ICIs) are effective against rare tumors.
- This review analyzes the literature on ICI therapy in rare cancer patients.
Approach:
- A comprehensive literature search was conducted on PubMed using various ICI drug names.
- Studies involving rare tumors treated with ICIs were included.
- Linear regression was used to correlate overall response rates with median survival.
Key Points:
- 62 publications (4,620 patients) were selected from 1,255 initial results.
- Most studies involved salvage therapy in pretreated patients; only four were randomized trials.
- A strong correlation (Spearman R² >0.9) between response rate and overall survival was observed in skin cancers, mesothelioma, and sarcomas.
Conclusions:
- ICI therapy demonstrates significant activity in advanced-stage rare tumors, including Merkel cell carcinoma and hepatocellular carcinoma.
- Ongoing prospective clinical trials aim to further elucidate the safety and efficacy of ICIs in rare cancers.
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