Drug Repurposing in Oncology: Accelerating New Cancer Treatment Strategies Through Existing Medicines

 

Drug Repurposing in Oncology: New Strategies for Faster Cancer Treatment Development

Cancer treatment continues to evolve as researchers search for safer, more effective, and more personalized therapeutic strategies. Although the development of new cancer medicines has produced major advances, discovering and bringing an entirely new drug to patients can require substantial time, investment, and extensive clinical evaluation.

One emerging strategy that has attracted increasing interest in oncology is drug repurposing. Also known as drug repositioning, this approach involves investigating medicines that are already approved or previously developed for one disease to determine whether they may be useful for treating cancer or a different cancer indication.

Rather than starting drug development from the beginning, researchers can leverage existing knowledge about a medicine's pharmacology, safety profile, mechanism of action, and manufacturing characteristics. This can potentially accelerate the development of new treatment strategies while opening new opportunities for patients with difficult-to-treat cancers.

Drug repurposing does not mean that an existing medicine automatically becomes a cancer treatment. Each proposed use must be supported by appropriate laboratory studies, clinical evidence, and regulatory evaluation. However, the strategy is becoming an important area of cancer research because it can connect established medicines with new biological discoveries.

At the World Conference on Oncology & Cancer Care (WCOCC-2026), emerging approaches such as drug repurposing represent the broader transformation taking place across cancer research, therapeutic development, and precision oncology.

What Is Drug Repurposing in Oncology?

Drug repurposing in oncology refers to the investigation of an existing medicine for a new cancer-related application.

A medicine may originally have been developed to treat:

• Cardiovascular disease
• Infectious diseases
• Neurological disorders
• Metabolic disorders
• Inflammatory diseases
• Autoimmune conditions
• Other medical conditions

Researchers may later discover that the same drug interacts with biological pathways that are important in cancer.

For example, a drug originally designed to influence a metabolic pathway may also affect tumor-cell metabolism. Similarly, a medicine developed for an inflammatory condition could potentially influence signaling pathways involved in the tumor microenvironment.

This creates an opportunity to investigate whether the existing medicine could have therapeutic value in oncology.

The process can involve laboratory experiments, computational analysis, retrospective clinical observations, translational research, and clinical trials.

Why Is Drug Repurposing Important for Cancer Research?

Traditional drug development is complex. Researchers must identify a promising target, discover or design candidate molecules, perform preclinical testing, evaluate safety, conduct clinical trials, and eventually seek regulatory approval.

Drug repurposing can potentially shorten some parts of this process because information about the existing medicine may already be available.

Researchers may already understand:

• Pharmacokinetics
• Pharmacodynamics
• Known adverse effects
• Drug metabolism
• Drug interactions
• Manufacturing characteristics
• Existing clinical experience
• Established dosing information

However, this does not eliminate the need for cancer-specific research.

A medicine that is safe and effective for one disease may behave differently when used in cancer patients, at different doses, or in combination with other therapies.

Therefore, drug repurposing should be viewed as a strategy for identifying promising candidates more efficiently—not as a shortcut around clinical research.

How Does Drug Repurposing Work?

Drug repurposing can follow several research pathways.

1. Mechanism-Based Repurposing

Scientists can investigate whether a known drug affects a molecular pathway involved in cancer.

Cancer cells depend on complex signaling networks for:

• Growth
• Survival
• Metabolism
• DNA repair
• Angiogenesis
• Immune evasion
• Metastasis

If an existing medicine influences one of these processes, researchers may investigate its potential anticancer activity.

2. Computational Drug Repurposing

Modern computational approaches can analyze large biological and pharmaceutical datasets to identify connections between existing drugs and cancer-related pathways.

Researchers can compare:

• Drug-target interactions
• Gene-expression profiles
• Molecular pathways
• Protein networks
• Cancer mutations
• Clinical datasets
• Drug-response information

Artificial intelligence and machine learning can further assist in identifying potential relationships that may be difficult to detect through traditional approaches.

3. Phenotypic Screening

Instead of beginning with a specific molecular target, researchers can test existing medicines against cancer cells or cancer models and observe their effects.

A compound may demonstrate unexpected activity such as:

• Reduced tumor-cell proliferation
• Increased cancer-cell death
• Changes in differentiation
• Reduced invasion
• Altered drug resistance

Such observations can lead to additional mechanistic research.

4. Clinical Observation

Sometimes potential repurposing opportunities emerge from real-world clinical observations.

Researchers may notice that patients receiving a particular medication for another condition demonstrate unexpected changes in cancer incidence, progression, or treatment response.

These observations do not prove that the medicine treats cancer, but they can generate hypotheses for further research.

Drug Repurposing and Precision Oncology

One of the most interesting future directions is the integration of drug repurposing with precision oncology.

Traditional cancer treatment often groups patients according to cancer type and disease stage. Precision oncology aims to understand the molecular characteristics of an individual patient's tumor and use that information to guide treatment decisions.

Tumors can differ in:

• Genetic alterations
• Gene-expression patterns
• Protein activity
• Metabolic characteristics
• Immune environment
• Drug sensitivity
• Resistance mechanisms

Drug repurposing can potentially be incorporated into this framework.

Instead of asking only:

“Which existing drugs have anticancer activity?”

researchers can increasingly ask:

“Which existing drug is most likely to work against this patient's specific tumor biology?”

This shift could make drug repurposing more targeted and biologically informed.

The Role of Molecular Profiling

Molecular profiling can help researchers identify patients whose tumors may contain vulnerabilities that correspond to the mechanism of an existing medicine.

Technologies such as:

• Genomic sequencing
• Transcriptomic analysis
• Proteomic profiling
• Molecular biomarker analysis
• Functional testing

can provide information about tumor biology.

Combining these data with drug-response information may help identify potential relationships between specific tumor characteristics and repurposed medicines.

This approach could ultimately support more individualized therapeutic strategies.

Drug Repurposing for Rare Cancers

Rare cancers often face significant challenges in drug development.

Because patient populations may be relatively small, recruiting sufficiently large clinical trial populations can be difficult. Commercial incentives for developing entirely new drugs may also be limited for some rare diseases.

Drug repurposing could provide another avenue for investigation.

Existing medicines with established safety information may offer researchers potential candidates for further study.

However, clinical trials remain essential for determining whether a repurposed medicine provides meaningful benefit in a specific rare cancer.

Drug Repurposing and Cancer Drug Resistance

Cancer treatment resistance remains one of the major challenges in oncology.

Cancer cells can develop resistance through multiple mechanisms, including:

• Genetic evolution
• Activation of alternative signaling pathways
• Changes in drug transport
• Altered apoptosis
• Tumor microenvironment interactions
• Cancer-cell plasticity

Repurposed medicines may potentially be investigated as part of combination strategies designed to overcome resistance.

For example, researchers may explore whether an existing medicine can interfere with a resistance pathway and restore sensitivity to another cancer therapy.

This area is particularly important because successful cancer treatment increasingly requires strategies that address tumor evolution and treatment resistance.

Combination Therapy and Drug Repurposing

Cancer rarely depends on a single biological pathway.

As a result, combination therapy is an important area of research.

A repurposed medicine could potentially be investigated together with:

• Chemotherapy
• Targeted therapy
• Immunotherapy
• Radiation therapy
• Hormonal therapy
• Other investigational treatments

The objective is not simply to add another drug but to determine whether the combination creates a meaningful biological advantage.

Researchers must carefully evaluate possible toxicity, drug interactions, dosing schedules, and pharmacological compatibility.

Drug Repurposing and Immunotherapy

Cancer immunotherapy has transformed treatment for several malignancies, but not every patient responds.

Some tumors remain resistant because of:

• Immunosuppressive tumor environments
• Poor immune-cell infiltration
• T-cell dysfunction
• Altered antigen presentation
• Immunosuppressive signaling

Existing medicines that influence immune pathways could potentially be investigated alongside immunotherapy.

Researchers are exploring whether drug repurposing can help modify the tumor environment or immune response in ways that make cancer cells more susceptible to immune-mediated destruction.

This represents an important research direction at the intersection of pharmacology, tumor biology, and cancer immunology.

Artificial Intelligence in Drug Repurposing

Artificial intelligence is becoming increasingly relevant to drug discovery and repurposing.

AI systems can analyze large datasets containing information about:

• Drugs
• Molecular targets
• Genes
• Proteins
• Cancer types
• Clinical outcomes
• Biological pathways
• Patient characteristics

Machine-learning models may help identify potential drug-disease relationships and prioritize candidates for experimental testing.

AI can also support drug-response prediction by integrating different types of biological information.

However, computational predictions are not equivalent to clinical evidence. AI-generated candidates must undergo appropriate laboratory validation and clinical evaluation.

The future of drug repurposing may therefore involve a continuous cycle:

Data → AI prediction → Laboratory validation → Preclinical research → Clinical trials → Patient evidence

Integrating Drug Repurposing with Multi-Omics

Cancer biology is highly complex, and no single biological dataset can fully describe a tumor.

Multi-omics approaches integrate different layers of biological information, potentially including:

• Genomics
• Transcriptomics
• Proteomics
• Metabolomics
• Epigenomics

Although multi-omics itself is already an established research area, its integration with drug-repurposing strategies may provide new opportunities for identifying therapeutic vulnerabilities.

For example, genomic data may reveal a mutation, while transcriptomic and proteomic information can provide insight into how that alteration affects cellular behavior.

Researchers can then investigate whether an existing drug interacts with the resulting biological pathway.

This type of integrated analysis could make drug repurposing increasingly mechanism-driven.

The Role of Biomarkers

Biomarkers can help identify patients who are more likely to benefit from a particular therapy.

In drug repurposing research, biomarkers may help answer several questions:

• Which tumors are sensitive to the drug?
• Which molecular pathway is being affected?
• Which patients are unlikely to respond?
• Can treatment response be monitored?
• Can resistance be detected early?

Biomarker-driven clinical research could therefore help move drug repurposing away from broad trial-and-error approaches toward more targeted therapeutic development.

Advantages of Drug Repurposing

Drug repurposing has several potential advantages.

Existing Safety Information

Previously studied medicines may have substantial safety and pharmacological information available.

Faster Candidate Identification

Researchers can begin with an existing compound rather than discovering an entirely new chemical entity.

Reduced Early-Stage Uncertainty

Some characteristics of the medicine may already be understood from previous development programs.

New Options for Difficult Cancers

Repurposing can generate new therapeutic hypotheses for cancers where treatment options remain limited.

Potential for Combination Strategies

Existing medicines may be investigated alongside established cancer therapies.

Data-Driven Discovery

Modern computational biology and AI can help researchers screen large numbers of existing medicines for potential cancer applications.

Challenges of Drug Repurposing in Oncology

Despite its promise, drug repurposing also presents significant challenges.

Different Disease Contexts

A medicine that works for one condition may not produce the same biological effect in cancer.

Dose Limitations

The dose required to produce an anticancer effect may differ from the dose normally used for the original indication.

If an effective cancer dose causes unacceptable toxicity, the repurposing strategy may not be clinically viable.

Limited Clinical Evidence

Laboratory findings do not automatically translate into patient benefit.

Patent and Commercial Challenges

Repurposed medicines may have limited commercial incentives, particularly when intellectual-property protection is no longer strong.

Drug Interactions

Cancer patients frequently receive multiple medications, increasing the importance of evaluating interactions.

Patient Selection

Without appropriate biomarkers or biological understanding, promising treatments may appear ineffective because they were tested in patients unlikely to benefit.

From Laboratory Discovery to Clinical Application

A successful drug-repurposing concept must progress through several stages.

Discovery

Researchers identify an existing medicine with potential anticancer activity.

Preclinical Validation

The candidate is investigated using appropriate cancer models.

Mechanistic Research

Scientists determine how the medicine may influence cancer biology.

Biomarker Development

Potential indicators of treatment response may be identified.

Clinical Investigation

The candidate is evaluated in appropriately designed clinical studies.

Regulatory Evaluation

Evidence regarding safety, efficacy, dosing, and risk-benefit balance must support any new therapeutic use.

This process demonstrates an important principle: drug repurposing can accelerate discovery, but it does not replace evidence-based cancer research.

Drug Repurposing and Patient-Centered Cancer Care

The ultimate goal of oncology research is to improve patient outcomes.

A repurposed medicine is valuable only if it can provide meaningful clinical benefit while maintaining an acceptable safety profile.

Future research may increasingly combine:

Patient characteristics + tumor biology + biomarkers + drug-response data + clinical evidence

to identify treatment strategies tailored to individual patients.

This approach aligns closely with the broader goals of personalized cancer care.

Future Directions

The future of drug repurposing in oncology is likely to become increasingly data-driven.

Several developments could shape the field:

AI-Based Drug Matching

Artificial intelligence may help connect existing medicines with specific cancer-associated molecular pathways.

Patient-Derived Models

Advanced laboratory models may help researchers test repurposed drugs against patient-specific tumor characteristics.

Functional Drug Testing

Instead of relying exclusively on genetic information, researchers may test how actual tumor cells respond to different medicines.

Biomarker-Guided Trials

Clinical trials may increasingly focus on molecularly defined patient groups.

Combination Strategies

Repurposed medicines may be evaluated as components of rational treatment combinations.

Real-World Data

Large clinical datasets may help researchers identify patterns that generate new repurposing hypotheses.

Precision Drug Repurposing

The long-term goal may be to identify not simply a repurposed drug for a cancer type, but the right repurposed treatment for a biologically defined group of patients.

Why Drug Repurposing Matters for the Future of Oncology

Cancer research is moving toward a more integrated model in which discoveries from molecular biology, computational science, pharmacology, and clinical medicine increasingly influence one another.

Drug repurposing fits naturally into this environment.

Instead of viewing the pharmaceutical landscape as a collection of medicines with fixed purposes, researchers can investigate whether established drugs have previously unrecognized biological effects.

With advances in AI, molecular profiling, functional testing, and precision medicine, the search for new cancer treatments may increasingly involve finding new possibilities within existing therapeutic resources.

The approach could be especially valuable when combined with strong biological evidence and carefully designed clinical research.

Conclusion

Drug repurposing in oncology represents an important strategy for exploring new cancer treatment possibilities using existing medicines.

By combining established pharmacological knowledge with modern cancer biology, molecular profiling, computational analysis, artificial intelligence, biomarkers, and clinical research, scientists can identify potential new applications for medicines that were originally developed for other diseases.

Drug repurposing is not a replacement for conventional drug development, and promising laboratory results must still be confirmed through rigorous clinical research. Nevertheless, it offers an attractive framework for accelerating the identification of potential cancer therapies and exploring new approaches to treatment resistance, combination therapy, and personalized medicine.

As oncology continues to move toward increasingly precise and patient-centered care, drug repurposing may become an important component of the broader cancer drug-development landscape.

Explore the Future of Cancer Research at WCOCC-2026

The World Conference on Oncology & Cancer Care (WCOCC-2026) will bring together researchers, oncologists, healthcare professionals, scientists, academics, and industry experts to discuss emerging developments across cancer research and clinical oncology.

📅 November 19–21, 2026
📍 Tokyo, Japan

Researchers and professionals interested in oncology, cancer research, drug development, precision medicine, cancer therapeutics, and emerging treatment strategies are invited to participate and share their research.

Frequently Asked Questions

What is drug repurposing in oncology?

Drug repurposing in oncology involves investigating an existing medicine for a new application in cancer treatment, prevention, diagnosis, or supportive care.

Why is drug repurposing important in cancer research?

It can help researchers identify potential therapeutic candidates using existing pharmacological and safety information, potentially accelerating certain stages of drug development.

Can any existing medicine be used to treat cancer?

No. A medicine must demonstrate appropriate evidence of safety and effectiveness for the proposed cancer application. Existing approval for another disease does not automatically establish its use in cancer.

How does AI support drug repurposing?

AI and machine-learning approaches can analyze large datasets involving drugs, molecular targets, genes, pathways, and clinical information to identify potential drug-cancer relationships for further investigation.

Can drug repurposing help overcome cancer drug resistance?

Researchers are investigating whether certain existing medicines can target mechanisms associated with treatment resistance and potentially improve responses when combined with cancer therapies.

How is drug repurposing connected to precision oncology?

Molecular profiling and biomarkers may help identify specific groups of patients whose tumors are more likely to respond to a particular repurposed medicine.

What is the future of drug repurposing in cancer treatment?

Future strategies may combine AI, multi-omics, biomarkers, patient-derived models, functional testing, and clinical data to identify more precise and effective repurposed cancer treatments.