By:DengYue International Business Division

With the rapid advancement of precision medicine, targeted therapies have become one of the most revolutionary treatment strategies in oncology. As a professional pharmaceutical wholesaler officially authorized by the Hong Kong Department of Health, Hong Kong DengYuemed has long been dedicated to the import and export of innovative specialty drugs for major chronic diseases and cancer, continuously introducing cutting-edge targeted therapies to frontline clinical practice worldwide.

We firmly believe that only by truly understanding how targeted drugs achieve their “precision attack” can physicians and patients maximize the benefits of individualized cancer treatment. In this article, we provide a systematic overview of the core mechanisms behind targeted cancer therapies from a professional medical perspective.

1. The Fundamental Difference Between Targeted Therapy and Traditional Chemotherapy

Traditional chemotherapy agents, such as platinum-based drugs and taxanes, work by interfering with DNA replication or microtubule function, thereby preventing cell division.

However, this approach is essentially non-selective. While chemotherapy can effectively kill rapidly dividing cancer cells, it also damages healthy tissues with high proliferation rates, including bone marrow, gastrointestinal mucosa, and hair follicles. As a result, patients often experience significant side effects.

Targeted therapy operates in a completely different way.

Instead of attacking all rapidly dividing cells, targeted drugs are designed to specifically recognize and inhibit molecular targets that are uniquely expressed or mutated in cancer cells, such as receptors, kinases, or fusion proteins. By blocking these cancer-driving signaling pathways at the molecular level, targeted drugs suppress tumor growth while minimizing damage to normal cells.

This selective mechanism is the key reason why targeted therapy is often described as “precision medicine.”

2. Two Major Types of Targeted Therapies and Their Mechanisms

2.1 Small-Molecule Targeted Drugs (Tyrosine Kinase Inhibitors)

Small-molecule targeted drugs typically have low molecular weight and can be orally administered, allowing them to enter cells and directly inhibit intracellular signaling pathways.

Classic Mechanism Example

EGFR-Mutated Non-Small Cell Lung Cancer

Osimertinib selectively targets EGFR mutations such as T790M. It competitively binds to the ATP-binding pocket of the EGFR tyrosine kinase domain, thereby inhibiting its enzymatic activity.

Once EGFR signaling is suppressed, downstream pathways including:

● RAS–RAF–MEK–ERK (MAPK)

● PI3K–AKT–mTOR

are effectively blocked. Without these growth signals, cancer cells lose their ability to proliferate and may ultimately undergo programmed cell death through caspase activation.

Chronic Myeloid Leukemia with BCR-ABL Fusion Gene

Imatinib is often referred to as the first successful example of a “magic bullet” in targeted therapy. It binds to the active site of the ABL kinase, preventing phosphorylation of the BCR-ABL fusion protein and thereby eliminating the proliferative signal driving leukemia cells.

Advantages of small-molecule targeted therapies include:

● Oral administration

● Potential penetration of the blood–brain barrier (particularly with third-generation EGFR inhibitors)

However, acquired resistance may eventually develop due to mechanisms such as secondary mutations (e.g., C797S) or activation of alternative signaling pathways.

2.2 Monoclonal Antibody Targeted Drugs (Biologic Therapies)

Monoclonal antibodies are large-molecule biologics typically administered through intravenous infusion. They mainly target cell surface receptors or antigens.

Classic Mechanism Example

HER2-Positive Breast Cancer

Trastuzumab binds to the extracellular domain of the HER2 receptor, producing multiple anti-tumor effects:

1.  Inhibits HER2 receptor dimerization and suppresses downstream PI3K/AKT and MAPK signaling pathways

2.  Recruits natural killer (NK) cells through its Fc region, triggering antibody-dependent cellular cytotoxicity (ADCC)

3.  Prevents shedding of the HER2 extracellular domain, reducing immune suppression caused by soluble HER2 fragments

CD20-Positive B-Cell Lymphoma

Rituximab targets the CD20 antigen on B cells and induces tumor cell destruction through several mechanisms:

● Complement-dependent cytotoxicity (CDC)

● Antibody-dependent cellular cytotoxicity (ADCC)

● Direct induction of apoptosis

In recent years, bispecific antibodies have further expanded the potential of targeted therapy. For example, drugs designed to simultaneously target PD-1 and VEGF can both block immune checkpoint signaling and inhibit tumor angiogenesis, producing synergistic anti-tumor effects.

3.  Three Key Steps Behind the “Precision Attack” of Targeted Drugs

The effectiveness of targeted therapy generally relies on three critical steps.

1. Target Identification

Before treatment begins, companion diagnostic testing is required to determine whether the tumor contains specific molecular targets.

Common diagnostic tests include:

● EGFR / ALK / ROS1 / NTRK gene testing

● HER2 IHC or FISH analysis

● PD-L1 expression testing

If the tumor does not harbor the corresponding target, targeted therapy is unlikely to provide meaningful clinical benefit. This requirement is the foundation of precision oncology.

2. Blocking Tumor-Driving Signaling Pathways

Once the drug binds to its target, it inhibits the signaling pathways that cancer cells depend on for survival and proliferation. This can lead to cell cycle arrest (often at the G1 phase) or directly trigger apoptosis.

3. Immune Activation and Bystander Effects

Certain antibody-based targeted drugs can recruit immune cells to attack tumor cells or indirectly stimulate T-cell responses through antigen release. This mechanism also provides the biological rationale for combining targeted therapy with immunotherapy.

4. Clinical Benefits and Ongoing Challenges

Targeted therapies have significantly improved outcomes for many cancer patients.

In several tumor types:

● Objective response rates (ORR) can reach 60–90%

● Progression-free survival (PFS) is substantially extended

For example, first-line targeted therapy for EGFR-mutated lung cancer can achieve a PFS of approximately 18–20 months, often with better quality of life compared to conventional chemotherapy.

However, drug resistance remains an inevitable challenge in targeted therapy. Major resistance mechanisms include:

● Secondary mutations in the target gene

● Activation of bypass signaling pathways (such as MET amplification or PI3K mutations)

● Remodeling of the tumor microenvironment

For this reason, DengYue Pharmaceutical not only introduces innovative targeted therapies but also closely follows the development of next-generation targeted drugs, including fourth-generation EGFR inhibitors, bispecific antibodies, and antibody-drug conjugates (ADCs).

Conclusion

As a professional platform specializing in the global import and export of innovative oncology medications, Hong Kong DengYue Pharmaceutical Co., Ltd. has supplied compliant imported drugs—including EGFR-TKIs, HER2 antibodies, and ALK inhibitors—to multiple tertiary hospitals and clinical research institutions. Through a strictly controlled cold-chain system, medications can be delivered within 72 hours under regulated temperature conditions.

Understanding the mechanisms of targeted therapy is a crucial step toward unlocking the full potential of precision medicine. With the advancement of multi-omics technologies and AI-assisted drug discovery, targeted cancer treatments are expected to become even more accurate and effective.

DengYue will continue collaborating with leading global pharmaceutical companies to introduce more breakthrough therapies to patients across China and the Asia-Pacific region, helping move cancer treatment from disease control toward long-term survival and potential cure.

For the latest information on targeted drug importation, clinical trial comparator drug supply, or in-depth discussions of targeted therapy mechanisms, please feel free to contact us.