What side effects of the skin can biological therapy cause?

This article reviewed the skin side effects caused by anti-PD-1 biological therapy.

Anti-PD-1 is a type of biological therapy that has significantly improved treatment results for patients with certain types of cancer. It works by blocking PD-1, a molecule that cancer cells use to switch off the immune system. When the immune system is switched on, it can kill cancer cells. 

However, around 40% of patients receiving anti-PD-1 therapy develop skin side effects. Nivolumab (Opdivo) and pembrolizumab (Keytruda) are the most commonly used anti-PD-1 drugs. A clear understanding of the type of skin side effects is needed so that they can be treated effectively or prevented.

114 studies that described skin side effects in 253 patients receiving anti-PD-1 therapy were identified.  The side effects fell into seven skin disorders.

Vitiligo, or depigmentation, is where the skin loses its color in patches. 56 cases of depigmentation were reported. This began 6 to 36 weeks after starting treatment. Generally, patients do not need to be treated for depigmentation but should use sun protection.

Psoriasis is a condition caused by a build-up of excess skin cells in scaly patches that can be itchy or painful. 33 cases of psoriasis were reported, 17 of which were new cases and 16 which were flare-ups of pre-existing psoriasis. This began 2 to 22 weeks after starting treatment. Most patients can be treated with corticosteroid and/or vitamin D creams. People with a personal or family history of psoriasis have a higher risk and this should be identified before beginning anti-PD-1 therapy.

Bullous pemphigoid is the name for fluid-filled blisters. 31 cases of bullous pemphigoid were reported. This occurred 3 to 84 weeks after beginning treatment. Patients can be treated with steroid creams or tablets. Some patients may need to pause or stop anti-PD-1 treatment.

Lichenoid reactions are hard and scaly patches of skin. Lichenoid reactions were reported in 29 patients. These developed several days after starting treatment to 92 weeks later. Steroid creams or tablets are used to treat patients.

Granulomatous skin reactions are a class of rash that is often itchy. 10 cases of granulomatous skin reactions were reported. Most cases developed within 12 weeks of starting treatment. Steroid tablets are effective at treating patients, although some patients may need to pause anti-PD-1 treatment.

10 cases of toxic epidermal necrolysis, Stevens-Johnson Syndrome, or erythema multiforme were reported. These three diseases are characterized by sores on the skin and are serious.  Most cases developed within four weeks after beginning treatment. Steroid tablets can be used to treat patients. Anti-PD-1 treatment should be paused.

Lupus erythematosus is caused by inflammation throughout the body, including the skin. 8 patients developed lupus erythematosus. This developed 4 to 34 weeks after starting treatment. Steroid creams or tablets can be used to treat patients. Anti-PD-1 therapy may need to be paused or stopped while patients recover.

The authors concluded that skin side effects are common in patients receiving anti-PD-1 therapy. Dermatologists should be consulted to prevent or treat these side effects.

Due to the small number of reports of patients with side effects, confirmation of the frequency of the side effects is needed.