How long does it take for Erdafitinib/Bocto to start killing cancer cells?

Erdafitinib (Erdafitinib) is an FGFR pathway inhibitor. The core of its anti-tumor effect is to block the proliferation and survival signals generated after activation of receptors such as FGFR2 and FGFR3. Theoretically, a drug can continue to inhibit relevant signaling pathways after reaching a stable blood concentration in the body. Therefore, the time it takes for it to "start working" often depends on the absorption speed, establishment of blood drug homeostasis, and target sensitivity. Erdafitinib reaches effective plasma concentrations within hours after oral administration, whereas steady state for most targeted drugs typically takes between days and two weeks to establish. Therefore, clinically, changes in patient symptoms, images, or tumor indicators are often observed in the first few weeks after treatment.

From a cellular level, erdafitinib has obvious selectivity for tumors with altered FGFR. When FGFR signals are suppressed, tumor cell proliferation ability decreases, and FGFR-dependent survival pathways are cut off, causing cancer cells to enter a state of apoptosis or stop growing. In other words, the drug takes effect not by "killing cancer cells immediately", but by gradually blocking the tumor's life-sustaining signals, causing it to gradually lose its ability to grow. This mechanism applies to tumors with FGFR gene abnormalities such as urothelial cancer (bladder cancer), so the therapeutic effect may vary among different populations.

Because FGFR inhibition will change blood phosphorus levels, doctors usually conduct intensive testing in the first few weeks after treatment to determine whether the drug has reached the target inhibition intensity, which also indirectly reflects the time window when the drug begins to exert its anti-tumor effect. Experience shows that many patients observe significant changes 2–6 weeks after the start of treatment, including pain relief, stabilization or shrinkage of lesions, as a result of effective blockade of the FGFR pathway.

In general, the "onset time" of erdafitinib is a typical progressive mechanism of targeted drugs, that is, it gradually weakens tumor activity under continuous action, rather than killing cancer cells all at once.

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