The Potential Anti-Cancer Properties of Hydroxychloroquine (Plaquenil) in Lupus

Evidence is Accumulating that Hydroxychloroquine Reduces Cancer Risk in Patients with A Diagnosis of Lupus

Hydroxychloroquine (trade name Plaquenil) is commonly used in the treatment of several autoimmune hair loss conditions including discoid lupus, lichen planopilaris and frontal fibrosing alopecia. 

Recent studies in the other fields of medicine have suggested that hydroxychloroquine might have an anticancer role - at least for some types of cancers - and at least in patients with certain autoimmune diseases. Hydroxychloroquine may do so by inhibiting a process in cancer cells known as “autophagy” thus limiting the access of cancer cells to nutrients. A variety of clinical trials are underway to examine the role of hydroxychloroquine as an adjuvant or “add on” in a variety of cancer treatments.

Recent studies suggest that hydroxychloroquine may reduce the risk of patients with lupus from developing some types of cancer.

The Potential Anti-Cancer Properties of Hydroxychloroquine in Patients with Lupus

Hydroxychlororquine may reduce cancer risk in patients diagnosed with systemic lupus erythematosus (also referred to as SLE, or ‘lupus).

Bernatsky et colleagues recently studied 1,668 patients with an average 9 years follow-up. The authors showed that the use of hydroxychloroquine in patients with lupus reduced the risk of breast and non melanoma skin cancer.

In a retrospective study in 2020 by Guo et al, the authors carried out a nested case-control study in a large cohort of 5858 SLE patients. The authors also found that use of hydroxychloroquine reduced the risk of cancer in patients with lupus.

In 2021 Xian Bao and colleagues performed a meta analysis of a total of nine studies consisting of four nested case-control, two case-cohort and three cohort studies. The results showed that antimalarials might reduce the risk of cancer in SLE by up to 30 % (RR = 0.68, 95%CI: 0.55-0.85). 

In some diseases, hydroxychloroquine does not seem to alter cancer risk. For example, a 2017 study showed In patients with Sjögren’s syndrome (another types of autoimmune disease), use of hydroxychloroquine did not seem to be associated with any sort of change in cancer risk

Other studies have suggested that hydroxychloroquine might not reduce the risk of developing cancer but may influence the behaviour of the cancer if a person gets cancer. For example, Fardet and colleagues showed in 2017 that Individuals on long-term exposure to hydroxychloroquine/chloroquine are not at lower risk of developing cancer. However, hydroxychloroquine/chloroquine may lower the risk of metastatic cancer and death.

Conclusion

The cancer research community has a keen interest in understand if hydroxychloroquine can have benefit not only as a drug to treat autoimmune diseases but as a drug to treat cancer. It’s not clear if hydroxychloroquine might have more benefit as an anticancer agent in certain groups of patients than others as more studies are needed. Among patients with lupus, it does seem that hydroxychloroquine has potential benefits in reducing the risk of certain types of cancers.

References

Bernatsky et al. Cancer Risk in a Large Inception Systemic Lupus Erythematosus Cohort: Effects of Demographic Characteristics, Smoking, and Medications. Arthritis Care Res (Hoboken). 2020 Aug 19;10.1002/acr.24425.

Fardet et al. Effects of chronic exposure of hydroxychloroquine/chloroquine on the risk of cancer, metastasis, and death: a population-based cohort study on patients with connective tissue diseases. Clin Epidemiol. 2017.

Guo et al. The relationship between cancer and medication exposure in patients with systemic lupus erythematosus: a nested case-control study. Arthritis Res Ther. 2020.

Marmor. Hydroxychloroquine During Cancer Therapy. Retin Cases Brief Rep. Spring 2019.

Xian-Bao Li et al. Antimalarials may reduce cancer risk in patients with systemic lupus erythematosus: a systematic review and meta-analysis of prospective studies. Ann Med. 2021 Dec.

Yao-Fan Fang et al. Hydroxychloroquine and risk of cancer in patients with primary Sjögren syndrome: propensity score matched landmark analysis. Oncotarget. 2017.