Mebendazole: A New Hope for Adrenocortical Cancer

A recent case report highlights a patient with chemotherapy- and radiation-resistant adrenocortical carcinoma (ACC), an aggressive endocrine cancer, who achieved significant tumor regression following treatment with mebendazole—a repurposed antiparasitic drug.

This unexpected outcome underscores the potential of mebendazole as a novel therapeutic option for advanced ACC, warranting further clinical investigation into its antitumor mechanisms.

Introduction

Adrenocortical carcinoma (ACC) is a rare and aggressive cancer that starts in the adrenal glands and small organs near the kidneys. With limited treatment options beyond surgery—primarily when the cancer spreads (metastasizes)—patients often face poor outcomes.

However, a study in Endocrine Practice highlights an unexpected candidate for treatment: mebendazole, a medication typically used to treat parasitic worm infections.

A Patient’s Journey

The study details a 48-year-old man diagnosed with metastatic ACC. Despite trying multiple standard therapies—including chemotherapy drugs like mitotane and 5-fluorouracil, as well as radiation—his cancer continued to spread. These treatments also caused severe side effects, leading him to stop them altogether.

A Surprising Switch

With conventional options exhausted, doctors prescribed mebendazole (100 mg twice daily) as a standalone treatment.

Remarkably, his metastases shrank over the next 19 months and stabilized. He maintained a good quality of life with minimal side effects, a stark contrast to the toll of chemotherapy.

However, after 24 months, his cancer began progressing again.

Why 24 Months of Quality Survival Matters

1. Adrenocortical Carcinoma (ACC) Prognosis:

   • ACC is a rare, aggressive cancer with a 5-year survival rate of 20–35% for localized tumors, dropping to <10% for metastatic disease.
   • Chemo/radiation-resistant ACC typically progresses rapidly, with median survival after treatment failure ranging from 3–6 months.

2. Quality of Life (QoL) Significance:

   • Patients with advanced ACC often experience severe symptoms (e.g., hormone excess, pain, fatigue) and side effects from aggressive therapies (e.g., mitotane, chemotherapy).
   • 24 months with minimal side effects and preserved QoL is exceptional, as it allows the patient to maintain daily activities, relationships, and emotional well-being—a critical goal in palliative oncology.

Survival Without Mebendazole: A Comparison

Key Contrasts:

1. Time Gained: Mebendazole provided 18–21 additional months compared to the typical post-treatment failure trajectory.
2. Quality vs. Quantity: Survival without mebendazole might involve prolonged hospitalization, palliative sedation, or debilitating therapies, whereas mebendazole’s tolerability allows meaningful life extension.
3. Therapeutic Void: After first-line therapies fail, options like immunotherapy or clinical trials are limited and rarely curative. Mebendazole fills a gap in this “last-resort” setting.

Mechanistic and Clinical Implications

• Mebendazole’s Role: Preclinical studies suggest it inhibits tumor microtubules, glucose uptake, and angiogenesis—mechanisms that may slow ACC growth without the toxicity of chemotherapy.
• Case Context: While this is a single case report, doubling survival time aligns with prior anecdotal evidence (e.g., mebendazole in glioblastoma). More extensive trials are needed, but the outcome challenges the nihilism often associated with resistant ACC.

Takeaway

This case highlights that mebendazole isn’t just about extending survival—it’s about extending functional survival, which is rare in advanced ACC.

For patients facing terminal prognoses, even modest gains in quality time represent a transformative outcome. This case report underscores the urgency of exploring repurposed drugs like mebendazole in rigorous clinical trials for ACC.

What Is Mebendazole?

Mebendazole is a low-cost, widely available drug used globally to treat intestinal worms. Recently, researchers have explored its potential against cancer, as lab studies suggest it may disrupt cancer cell growth.

This case study adds to the growing interest in “repurposing” existing drugs for new uses, offering faster, cheaper alternatives to developing new therapies.

Why This Matters

ACC is notoriously hard to treat once it spreads, and this case offers hope for a well-tolerated option.

Mebendazole’s mild side effects (e.g., occasional stomach discomfort) make it appealing compared to harsh chemotherapy regimens.

However, this is just one patient’s story—a crucial point. While promising, the cancer eventually progressed, underscoring the need for further research to confirm benefits and optimize dosing.

The Big Picture

This study is a stepping stone. Researchers stress that larger clinical trials are needed to validate mebendazole’s effectiveness and determine why the cancer resumed growing after two years.

Could combining it with other therapies improve results?

How does it work against ACC? These questions remain unanswered.

Conclusion

While not a cure, mebendazole represents a potential lifeline for patients with limited options. Its affordability and tolerability make it an exciting candidate for further study.

For now, this case reminds us that sometimes answers to complex problems—like treating rare cancers—may lie in unexpected places.

Based on a study published in Endocrine Practice (May-June 2011). Always consult a healthcare provider before considering new treatments.