Fenbendazole Enhancing Anti-Tumor Effect: A Case Series (2021)
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Background
Fenbendazole (FBZ) is a cheap and readily available anti-parasitic commonly used in veterinary medicine.
FBZ belongs to the benzimidazole drug class which destabilize microtubules through a mechanism similar to the anti-oncogenic vinca alkaloids.
Although there are no reported cases in the literature, there have been several anecdotal stories published on website blogs with individuals praising its ability to treat a wide variety of cancers.
Case Presentations
Three patients with various genitourinary malignancies,
who demonstrated complete response after receiving FBZ therapy,
as a single or supplementary chemotherapeutic agent.
In two patient scenarios, they had experienced progression of metastatic disease despite multiple lines of therapy prior to initiation of FBZ.
No side effects from FBZ were reported.
Conclusion
FBZ appears to be a potentially safe and effective antineoplastic agent,
that can be repurposed for human use in treating genitourinary malignancies.
Further research is necessary to define the role of FBZ as a chemotherapeutic option.
Details
FBZ is a cheap anti-helminthic medication commonly used in veterinary practice,
However, despite multiple anecdotal stories and news outlet reports for its efficacy in treating metastatic cancer,
the clinical literature behind utilizing FBZ as a potential anti-neoplastic agent remains nonexistent.
Case 1
A 63-year-old Caucasian male presented with flank pain, rapid weight loss, and transient fever.
Abdominal Computed Topography (CT) revealed a 3 cm left solid renal mass.
Renal Cell Carcinoma (RCC)
Traditional drugs used then discontinued
One month after discontinuation, repeat MRI showed increase in size of recurrent left renal mass, pancreatic head and body lesion
He also started alternative therapy with FBZ 1 gm three times per week at the suggestion of one of his friends with head/neck cancer.
Interval MRI imaging found near complete resolution of the previously noted left renal mass,
as well as decrease in pancreatic head/body and pelvic bone lesion
Serial imaging for the past 10 months have not shown any evidence of recurrence or metastatic disease.
He has continued taking FBZ without any reported side effects.
Case 2
A 72-year-old caucasian male
Urethral lesion
Distal penectomy
Pathology showing high-grade urothelial carcinoma of the urethra
Four years later, the patient developed a cough,
5.5 cm × 4.0 cm left hilar mass and a left upper lobe nodule, with multiple abnormal lymph nodes
Bronchoscopy with biopsy revealed squamous carcinoma, (probable primary)
Chemotherapy given
Developed progressive retroperitoneal disease
The patient opted for complementary therapy with FBZ 1 gram orally three days per week,
vitamin E 800 mg daily,
curcumin 600 mg daily,
and CBD oil
Serial CTs from the past 9 months showed progressive decrease in size to 0.5 cm × 0.5 cm, complete radiographic response.
Case 3
A 63-year-old Caucasian female
CT imaging revealed a 7.5 cm right lateral bladder mass with extensions
Hydronephrosis requiring percutaneous nephrostomy.
Transurethral Resection of Bladder Tumor (TURBT) demonstrated a large necrotic mass,
pathology confirming urothelial carcinoma with 85% squamous and 2% sarcomatoid histology.
6 cycles over the course of 4 months,
along with concurrent FBZ 1 gram three times weekly.
Follow-up CT revealed no evidence of disease with minimal residual thickening in the right inferior bladder wall
She declined to proceed with cystectomy and remains on surveillance with no evidence of progression.
Discussion
We have three patients with different primary genitourinary tumors who demonstrated complete response after receiving FBZ therapy.
Given evidence of high tolerability and applicability to a wide range of malignancies,
this warrants further investigation for FBZ and other benzimidazoles as safe chemotherapeutic options.
Conclusion
There remains limited data with few published studies on the anti-oncogenic properties of FBZ.
Other benzimidazoles have been studied to a larger extent,
and the knowledge can be drawn upon to help guide future FBZ studies,
and to gauge the efficacy of this drug class whether as a solitary agent or in combination therapy.
Given the potential benefits of FBZ with what seems to be a limited toxicity profile,
further research is warranted to evaluate the clinical settings in which this medication may be beneficial and repurposed,
for patients with progressive genitourinary malignancy and possibly in other malignant settings as well.
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