Avelumab and Merkel Cell Carcinoma: Examining Biological Plausibility and Causation

From General Health Education to Occupational Exposure Concerns

Historically, public health communication on general health and science topics has emphasized broad preventive behaviors and awareness of common risk factors. This legacy framework provides a foundation for understanding how environmental and pharmaceutical exposures can influence disease development, even when the mechanisms are not fully delineated. In the context of mass production settings, where workers may encounter a range of chemical and biological agents, the transition from general health education to specific occupational exposure concerns becomes critical. One such area of emerging interest involves the relationship between exposure to certain therapeutic agents, such as immune checkpoint inhibitors, and subsequent health outcomes. For instance, the use of Avelumab in clinical practice has prompted questions about its potential role in altering immune surveillance, which could theoretically influence the risk of malignancies like Merkel cell carcinoma. While the biological plausibility of such an association is a subject of ongoing investigation, it is essential to consider that occupational settings may involve unique exposure patterns, including repeated or high-dose contact with pharmaceutical compounds. This shift in focus from general health information to the specific risks faced by production workers underscores the need for targeted surveillance and risk communication strategies that address the distinct vulnerabilities of this population.

Avelumab: Mechanism of Action and Therapeutic Context

Avelumab is a fully human IgG1 monoclonal antibody that functions as an immune checkpoint inhibitor by targeting programmed cell death ligand 1 (PD-L1) (https://pubmed.ncbi.nlm.nih.gov/29799096/). It has been approved in the USA, the EU, and Japan for the treatment of metastatic Merkel cell carcinoma (MCC), a rare and aggressive neuroendocrine cutaneous malignancy with poor prognosis (https://pubmed.ncbi.nlm.nih.gov/29799096/; https://pubmed.ncbi.nlm.nih.gov/33439294/). The approval was based on the JAVELIN Merkel 200 trial, in which confirmed objective responses were observed in approximately one-third of patients with chemotherapy-refractory metastatic MCC treated with avelumab (https://pubmed.ncbi.nlm.nih.gov/29799096/). Despite this therapeutic benefit, the use of avelumab raises questions about biological plausibility for causing or exacerbating MCC, as well as the adequacy of warnings and causation considerations for affected patients.

Biological Plausibility of Avelumab-Related Merkel Cell Carcinoma

The biological plausibility of avelumab-related MCC must be examined through mechanistic pathways. MCC is etiologically linked to the human Merkel cell polyomavirus in approximately 80% of cases, while the remaining 20% are induced by UV light leading to mutations (https://pubmed.ncbi.nlm.nih.gov/34445385/). Avelumab, as an anti-PD-L1 inhibitor, blocks the PD-1/PD-L1 interaction, thereby enhancing T-cell responses against tumor cells (https://pubmed.ncbi.nlm.nih.gov/34445385/). However, immune checkpoint inhibitors can also cause overactivation of the immune system, leading to immune-related adverse events (irAEs) (https://pubmed.ncbi.nlm.nih.gov/31543781/). In the context of MCC, avelumab therapy has been associated with irAEs such as hypercalcaemia due to reactivation of sarcoidosis (https://pubmed.ncbi.nlm.nih.gov/31543781/). While avelumab is primarily used to treat MCC, its immunomodulatory effects could theoretically promote tumor progression in certain scenarios, such as through down-regulation of MHC complexes or induction of anti-inflammatory cytokines, which are mechanisms of resistance to immune checkpoint inhibitors (https://pubmed.ncbi.nlm.nih.gov/34445385/). Nevertheless, the evidence does not directly demonstrate that avelumab causes de novo MCC; rather, it is a treatment for existing MCC, and its use may be associated with refractoriness or progression in some patients.

Risk Context: Warnings, Refractoriness, and Causation Considerations

Regarding risk anchors, the adequacy of warnings for avelumab and MCC is informed by clinical data. Avelumab is approved for metastatic MCC, and its prescribing information likely includes warnings about irAEs, but specific warnings about avelumab causing MCC are not supported by the evidence. The literature indicates that avelumab is a standard treatment for MCC, and response rates to PD-1/PD-L1 inhibition can reach up to 62% (https://pubmed.ncbi.nlm.nih.gov/36450381/). However, approximately 50% of patients do not respond or develop irAEs (https://pubmed.ncbi.nlm.nih.gov/34445385/). For avelumab-refractory patients, alternative treatments such as combined ipilimumab and nivolumab have shown efficacy, with three out of five patients responding in one study (https://pubmed.ncbi.nlm.nih.gov/33439294/). This suggests that avelumab refractoriness is a recognized clinical challenge, and warnings should address the possibility of non-response or progression. Causation-related considerations for affected patients involve the timeline between avelumab exposure and documented harm. The JAVELIN Merkel 200 trial demonstrated responses in chemotherapy-refractory patients, but the timeline for onset of irAEs or tumor progression is not explicitly detailed in the provided evidence. One case report describes hypercalcaemia due to sarcoidosis reactivation during avelumab treatment, which was managed with corticosteroids and allowed continuation of therapy (https://pubmed.ncbi.nlm.nih.gov/31543781/). This indicates that irAEs can occur during treatment, but the causal link between avelumab and MCC development is not established. Instead, avelumab is used to treat MCC, and any harm is more likely related to treatment failure or irAEs rather than causation of the disease itself. In summary, the evidence supports that avelumab is an effective treatment for metastatic MCC, but its use is associated with irAEs and potential refractoriness. The biological plausibility for avelumab causing MCC is low, as it is a therapeutic agent for the disease. Warnings should focus on irAEs and treatment resistance, and causation considerations should distinguish between treatment-related harm and disease progression. The timeline between exposure and harm is typically during or after treatment, with irAEs managed by corticosteroids.

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Frequently Asked Questions

Can avelumab cause Merkel cell carcinoma?

Current evidence does not support that avelumab causes de novo Merkel cell carcinoma (MCC). Avelumab is an immune checkpoint inhibitor used to treat metastatic MCC. Its mechanism enhances T-cell responses against tumor cells, but it may also lead to immune-related adverse events. The biological plausibility for causing MCC is low, as it is a therapeutic agent for the disease. (https://pubmed.ncbi.nlm.nih.gov/34445385/)

What are the risks associated with avelumab treatment for MCC?

Avelumab treatment is associated with immune-related adverse events (irAEs) such as hypercalcaemia due to sarcoidosis reactivation, and approximately 50% of patients may not respond or develop irAEs. Refractoriness is a recognized clinical challenge, and alternative treatments like combined ipilimumab and nivolumab may be considered. (https://pubmed.ncbi.nlm.nih.gov/31543781/; https://pubmed.ncbi.nlm.nih.gov/34445385/)

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This page is for educational and informational purposes only and is not medical or legal advice. Consult a licensed professional for case-specific guidance.