Targeted therapies

What is it ?

Unlike chemotherapy, which is non-specific, targeted therapies are specific to an anomaly responsible for tumor development :

• either a molecular anomaly (mutation within the tumor, most often non-hereditary)
• or a unique mechanism of tumor cell development.

They are part of what is known as “precision medicine”.

How it works ?

Targeted therapies are primarily administered orally, but some can also be given via injection, intravenous, or subcutaneous routes.

The proliferation of tumor cells is governed by various successive stages triggered by external signals to the cell (growth factors) that initiate a chain reaction on the cell's surface and then inside the cell, leading to its division into 2 new cells, which in turn have the ability to divide into 2, and so on."

Targeted therapies can act at different levels :

• Directly by preventing the growth factor from reaching the cell surface, thereby blocking its stimulation
• By preventing the binding of this factor to the cell surface
• By blocking the transmission of the proliferation signal carried by this factor into the cell.

Special cases of anti-angiogenic treatments :

One of the mechanisms of development in certain cancers is what is known as tumor neoangiogenesis.

This involves the creation of blood vessels by the tumor.

These vessels, like a pirate connection, facilitate the tumor's vascularization necessary for its growth and also the spread of tumor cells into the bloodstream.

Anti-angiogenic treatments (either monoclonal antibodies administered via infusion or VEGF inhibitors, the 'fertilizer' for blood vessels, in tablet form) prevent the formation of these blood vessels.

Joëlle, 71, shares her experience with her battle against breast cancer and her treatment with targeted therapy.

Side effects

Although targeted, these medications can still be toxic to healthy cells when the target is redundant, meaning it is also essential for the proliferation of normal cells. The side effects vary depending on the class of the drug.

Most often, these side effects are early and occur within the first few weeks of treatment. They are usually easily managed with simple symptomatic treatments, but sometimes dose adjustment may be necessary (dose reduction and/or treatment discontinuation).

For therapies targeting EGFR, for example, the side effects are primarily :

• Skin issues: hand-foot syndrome with redness and hyperkeratosis of the palms and soles, folliculitis
• Digestive issues: diarrhea

Anti-angiogenic therapies can cause :

• High blood pressure
• Protein leakage in the urine
• Bleeding
• Wound healing issues
• Less commonly, thromboses: Blood clots in the blood vessels, primarily veins

Indications

Targeted therapies often require specific testing for the targeted tumor anomaly in each patient, using a biopsy or the surgical specimen after surgery. This process is part of personalized medicine.

Some targeted therapies, particularly anti-angiogenics, don’t require specific analysis, but their use is limited to certain tumor types where this mechanism is identified as crucial in tumor development.