Unlike with other psoriasis treatments, there is clear evidence that many biologic drugs tend to become less effective over time.
Biologic drugs are structurally similar to hormones or other components in the human body, which is central to their possible loss of efficacy. “Biologics lose effectiveness over time because the immune system in some patients learns to recognize the biologics as foreign material and develops mechanisms to neutralize the biologics,” says Chiu.
It generally takes at least 6 months, and usually at least 1 to 2 years, for biologic drugs to start losing their effectiveness in a significant way in psoriasis, Lewis says. But even when a drug becomes less effective, it may still be effective enough for a while before a patient and doctor decide to switch to another drug.
One study found that after 10 years, people with psoriasis were still taking the same biologic drug only 26 percent of the time, on average, with most people switching to another drug due to lack of effectiveness.
The good news is that resistance to biologics is not a class effect, meaning that it won’t apply to another drug in the same class — such as TNF inhibitors or IL-17 inhibitors. “So we could switch to another biologic in that class, or we might switch classes if we’ve exhausted the best options in that class,” says Lewis.
Sometimes a biologic drug will start to wear off before someone’s next dose is due, Lewis says, but that’s not the same thing as your body becoming less responsive to the drug over time. Usually, he says, this effect is mild, and people can either tolerate their psoriasis symptoms or use topical drugs to control them until their next dose of a biologic is due.
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