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New Targets for Existing Drugs May Offer Benefits To Cancer Patients
New approaches to treating lung cancer may already be out there without the medical community knowing it yet, and a process called drug repurposing could be the missing link to such discoveries.
What is drug repurposing?
Drug repurposing is using drugs that were originally developed for one condition to treat another disease or condition. Drug repurposing also has several other names, including drug repositioning and drug re-profiling. Drugs that are adapted to treat cancer are sometimes called repurposed non-oncology drugs. As of 2018, 75 drugs had been repurposed to treat diseases or conditions other than the one that they were developed to treat. Some drugs that are repurposed may have the potential to treat multiple diseases or conditions, but have only been tested in one, and some may be found to be more effective when combined with other drugs.
There are three reasons why scientists and researchers repurpose drugs rather than developing new ones. One has to do with time, one with cost, and one with having knowledge of effectiveness and toxicity of current drugs on the market. According to a study published in Current Oncology in 2023, the average time to develop a new cancer drug is 8.3 years compared to 3 to 4 years to repurpose an existing drug for cancer treatment. Some established drugs can skip a phase I clinical trial, which is a study done in a small group of people to determine whether a medication can be used by humans and the proper dosage for it. (This is not always the case, and sometimes if a drug is used in a different population than the original it will take just as long to test). It is also significantly less expensive to repurpose drugs than to develop new ones. It only costs about $300 million to bring a repurposed drug to market, versus $2 to $3 billion to develop a new one. Also, having knowledge of toxicity of existing drugs allow greater safety going forward.
Apart from cost and time factors, there are also medical reasons why drug repurposing makes sense. The success rate for developing a new cancer treatment or medication is only about 2%, so it makes sense to explore other uses for drugs that have already been approved for other purposes.
How do scientists repurpose drugs?
Be sure to listen to Backstage @ Upstage podcast, “Everything Old Is New Again: Imagine This; Repurposing Existing Drugs for New Uses”, with Jane Wilkinson and Jaime Cheah for a description of exciting innovations in repurposing drugs.
Drugs are usually repurposed in one of three ways: by computational methods, biological methods, and mixed methods.
When scientists and researchers use the computational method, they collect database information on chemical structures, gene expression, and proteins that would be affected by the drug, or may look into electronic health records of patients who have had experience with the drug. Machine learning approaches help with this type of computational research. Although it isn’t the same as laboratory testing, computational analysis can give doctors and researchers ideas of which drugs may be good candidates for repurposing. The biological method is more experimental than the computational method and involves performing experiments on animals, evaluating the effectiveness of repurposing drugs through clinical trials, looking at how the drug binds to its targets and which targets might be similar enough to be impacted by the drug, or examining the overall function of a group of cells in response to a medication administered to it. Mixed approaches usually start with computational research and later validate or test the results of that research with biological experiments or clinical trials. This makes the development process faster and more effective than biological or computational approaches alone.
Repurposing drugs to treat lung cancer
This blog post is not intended to be a comprehensive explanation of drug repurposing as it relates to lung cancer but will touch on several recent drug repositioning discoveries that may work to treat lung cancer.
In July 2024, Science Daily covered a study that explored using a diabetes drug (which has been approved in several countries but is not yet approved in the United States) to treat lung cancer. This drug helps to ensure that non-small-cell lung cancer cells don’t develop resistance to chemotherapy, which extends the usefulness of the treatment.
Another study in early 2022 looked at the delivery method for drug-repositioning for lung cancer. When patients are given repurposed drugs that typically treat conditions that they may not have, those drugs build up in the liver, kidney and spleen. There are several anti-tumor medications that are usually administered through inhalation; however, those medications also have multiple side effects. One promising development involves loading repurposed drugs onto nanocarriers, tiny particles which can deliver the drugs directly to the lungs. There, smaller particles and larger particles of the medication get deposited in different parts of the lungs, ensuring more even coverage.
Other research on repurposing drugs for cancer involves beta blockers; using an arthritis medication to block cyclooxygenase or COX enzymes, which allow tumors to more easily metastasize; using cholesterol medication for its tumor suppressing abilities; or using diabetes-related medicine to block the activation of genes that cause cancer.
Stay tuned for more innovation in repurposing drugs!
Sources:
Drug Repurposing in Non-Small Cell Lung Carcinoma: Old Solutions for New Problems | PMC (nih.gov)
Diabetes drug reduces drug resistance in lung cancer, improving chemotherapy effectiveness | ScienceDaily
Inhalation delivery of repurposed drugs for lung cancer: Approaches, benefits and challenges | ScienceDirect
Drug repositioning in non-small cell lung cancer (NSCLC) using gene co-expression and drug–gene interaction networks analysis | Nature Scientific Reports
Current Landscape of Therapeutic Resistance in Lung Cancer and Promising Strategies to Overcome Resistance – PMC (nih.gov)
Review of Drug Repositioning Approaches and Resources | PMC (nih.gov)
Drug repurposing: a promising tool to accelerate the drug discovery process | ScienceDirect