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The use of topical imiquimod was found to effectively promote regression of precancerous cervical lesions, according to a phase II randomized controlled trial.

In a per-protocol population of women with high-grade squamous intraepithelial lesions (HSIL) of the cervix, histologic regression of lesions was observed in 60.5% of patients receiving weekly treatment with imiquimod compared with just 22.5% in the control group (P=0.001), resulting in a number needed to treat (NNT) of 2.63, reported Bruno O. Fonseca, MD, of Barretos Cancer Hospital in São Paulo, Brazil, and colleagues.

HSIL of the cervix, which are induced by human papillomavirus (HPV), are a precursor to cervical cancer. The standard treatment is surgical excision by either cold knife conization, laser conization, or a loop electrosurgical excision procedure (LEEP).

"However, surgical excision is associated with obstetric complications such as preterm delivery, premature rupture of amniotic membranes, chorioamnionitis, low birth weight, admission of the newborn to the intensive care unit, and an increase in perinatal mortality," the authors wrote in .

"This is a disease that affects women in the prime of their reproductive life," Mark Einstein, MD, MS, of Rutgers New Jersey Medical School in Newark, told MedPage Today.

Einstein, who was not involved in the study, noted that the number of LEEP procedures performed per year in the U.S. -- approximately 500,000 -- indicates the scope of the disease. Additionally, he pointed out that due to the association between LEEP and preterm births, "it is truly important to explore these nonsurgical agents."

Imiquimod directly activates innate immune cells through Toll-like receptors 7 and 8, resulting in production of cytokines and interferons.

Fonseca and colleagues evaluated the histologic response of cervical HSIL -- defined as regression to cervical intraepithelial neoplasia (CIN) 1 -- after topical application of 5% imiquimod cream.

The study enrolled 90 women ages 25 to 50 with a confirmed diagnosis of CIN 2 to 3 from August 2017 through April 2019 at Barretos Cancer Hospital: 49 were randomized to receive imiquimod, applied directly to the cervix weekly for 12 weeks, followed by LEEP, and 41 were randomized to LEEP with no preceding treatment (control group).

The authors found that histologic regression was higher in the imiquimod group versus the control group in both per-protocol and intention-to-treat (ITT) analyses.

In the ITT population, regression occurred in 53.3% of the specimens in the imiquimod group compared with 22.5% in the control group (P=0.004), resulting in a NNT of 3.25 (95% CI 2.0-9.1).

In the experimental group, surgical margins were negative for HSIL in 94.7% of the per-protocol population and 88.9% of the ITT population compared with 70% of patients in the control group.

Rates of adverse events were 73.7% in the per-protocol population and 77.8% in the ITT population of the imiquimod group. Most adverse events were mild, with abdominal pain being the most common. Three patients had grade 2 events, including vaginal ulcer, vaginal pruritus with local edema, and moderate pelvic pain.

"We observed histologic regression (to CIN 1 or less) in more than half of patients, which suggests this might be an alternative strategy to a cervical excision procedure," wrote Fonseca and co-authors.

"That's a good response rate, though not as good as LEEP, which is closer to 90% effective," said Einstein. "And it's not without its difficulties. There's some inconvenience to it, and some toxicity -- the biggest being abdominal pain."

"But this agent is very common, inexpensive, and something that can be applied pretty easily," he continued, "and not only in the United States, but globally in low- and middle-income countries. And that's critically important."

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