Well-known Anthelminthic Drug Shows Promising Result in Cancer Treatment

Drug or chemotherapy has a special place in cancer treatment as medications can penetrate most of the organs and may be useful in almost any stage of cancer and against different types of malignancies. Not to mention that taking drugs is more accessible than surgery or radiotherapy.

However, everyone knows the numerous side effects that come with traditional chemotherapy. The cost of chemotherapy also remains a barrier to treating cancer.

Wouldn’t it be great if some commonly used, cheaply available drug with established safety records could help treat cancer?

It seems that drugs commonly used to kill or expel parasitic worms from the body may have anticancer properties.

Anti-parasitic drugs may help kill tumor cells

Modern researchers have identified anti-cancer properties in many medicines used to treat other medical conditions. They have found that a group of medications used to treat parasitic diseases or helminthic manifestations can, in fact, help cancer patients.

Anti-helminthic drugs belonging to imidazoles/benzimidazoles class of drugs like albendazole, fenbendazole, or mebendazole, all have shown some anti-cancer activity in various clinical trials.

There are numerous reasons for the interest in these medications. These drugs have been in widespread use in medicine since the 1970s, with proven safety record in humans. They are widely available and do not cost much. Studies show that they act against cancer cells in many ways, thus reducing the chances of development of resistance towards them. Moreover, it seems that they can be safely combined with other anti-cancer medications.

How benzimidazoles help/work against cancer?

All benzimidazoles work in a more or less similar way, with some differences in the mechanism. They may also have a different safety profile. One of the reasons for interest in these drugs is that they kill cancer cells in multiple ways, as shown in earlier studies.

Most well-demonstrated mechanism of action of these drugs (fenbendazole, albendazole, and so on) is their effect on microtubules. By preventing or disrupting the production of microtubules, a kind of proteins, these drugs interrupt the growth of cancer cells, prevent the transportation of nutrients to malignant cells, and may also hinder the formation of DNA in these atypical cells. This mechanism is somewhat similar to more potent anticancer drugs like vinblastine, paclitaxel, docetaxel, and so on.

These drugs also work by inhibiting other enzymes necessary for cellular metabolism. Thus, they severely interrupt the energy supply to cancer cells. Since cancer cells are metabolically more active than healthy cells, any such disruption is more harmful to them when compared to healthy cells.

Some recent studies show that benzimidazoles, or albendazole more specifically, may help suppress vascular endothelial growth factor (VEGF). VEGF inhibition prevents the growth of new blood vessels in tumors (inhibiting angiogenesis), thus starving the fast-growing tumors and leading to their death.

What kind of cancers can be treated with benzimidazoles/anthelminthic drugs?

It is still an area of ongoing research. However, initial experience with these medications suggests that they may be effective against various cancers as a part of anticancer therapy. They are not probable to be used as a monotherapy, instead, in combination with other well-known drugs. When combined with other chemotherapy drugs, they not only increase their effectiveness but also prevent the development of resistance to these drugs.

These medications may have a role in the treatment of breast, small cell lung, hepatic, head and neck, bile duct, and many other types of cancers.

Albendazole shows the promising result in cancer treatment in a study

A recent study demonstrated the safety and efficacy of albendazole in the treatment of cancer. It was a phase one study with a primary focus on drug safety. Most clinical researches start with establishing safety before efficacy.

One may ask why a safety study was needed for a medication that has been in clinical use since the mid-1970s. The reason is simple; the anti-cancer dose of albendazole and duration of therapy is prolonged in comparison to its use as an antiparasitic agent. This means that doctors first need to establish the maximum non-toxic dose of the drug for cancer treatment.

In the study, 36 patients were enrolled living with various tumors like colorectal, gastric, mesothelioma, pancreas, lung, ovarian, prostate, biliary, head and neck, uterine, breast, melanoma, and so on. All these were solid and refractory tumors, that is, patients not responding to chemotherapy with well-known drugs.

The study found that cancer patients can tolerate up to 2.4 gm of albendazole a day. Out of these 36 participants, only 24 could be assessed for tumor markers. Out of these 24 patients, four of them showed better results than others with tumor markers falling more than 50% from baseline after treatment with albendazole.

Further, all patients demonstrated change/reduction in VEGF concentrations. This fall was exceptionally sharp and predictable in the first eight hours. Although, samples taken later demonstrated huge variations. In practice, it means that apart from killing cancer cells by inhibiting the formation of microtubules (vital protein), albendazole may prevent the formation of new blood vessels in tumors and thus promoting their shrinkage.

Figure 1 Three patients with refractory tumor/cancer demonstrated marked fall in tumor markers, thus confirming the role of albendazole in cancer treatment (Image Source: Pourgholami MH, Szwajcer M, Chin M, et al. Phase I clinical trial to determine maximum tolerated dose of oral albendazole in patients with advanced cancer. Cancer Chemother Pharmacol. 2010;65(3):597-605. doi:10.1007/s00280-009-1157-8)

What’s the conclusion regarding the role of albendazole in cancer treatment?

These trials are still in the early stages. What these trials have established is the safe and effective anticancer dose of albendazole. These studies have also shown various mechanisms of action of the drug. It is interesting to note that the above-mentioned study was done in refractive cases of cancer.

Therefore, it would be safe to say that this widely available drug has the potential to improve cancer treatment when used along with other therapies. It may even help treat tumors unresponsive to other medications.

However, since every cancer type differs, and so does every cancer patient, there is still a need for more extensive clinical trials to justify the use of albendazole in cancer treatment and understand its exact role.

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