The First FDA-Approved Drug for Squamous Cell Skin Cancer: Cemiplimab

On 28 September 2018, the United States Food and Drug Administration (FDA), for the treatment of metastatic, locally advanced or surgically unresectable squamous cell skin cancer, approved a new immunotherapy, cemiplimab (brand name Libtayo). Cemiplimab is the first FDA-approved treatment for advanced squamous cell skin cancer.

Skin cancers are among the most common cancers, and most have low metastatic potential. Because they also develop in visible areas, skin cancers are often detected early.

According to their cells of origin, skin cancers are broadly divided into melanoma (originating in melanocytes, the cells that give skin its color) and non-melanoma (non-melanoma), with approximately %95 belonging to the non-melanoma types. Non-melanoma skin cancers have common forms, basal cell cancer and squamous cell cancer , the 2 main types. By frequency, skin cancers rank as follows (most to least common): basal cell, squamous cell and melanoma. Squamous cell skin cancer affects 700 thousand new people annually in the United States alone. Sunlight is the main risk factor for all skin cancers.

Figure below: The 3 most common skin cancer types, a normal mole and their characteristics:

The vast majority of non-melanoma skin cancers can be treated successfully with simple methods such as cryotherapy (freezing), curettage and electrodesiccation, topical creams (fluorouracil, imiquimod) or surgical removal. With more advanced tumors, more extensive surgery or radiotherapy is usually sufficient to control regional disease. For metastatic skin cancer (spread throughout the body), treatment depends on whether it is basal or squamous cell cancer, but options are very limited.

While basal cell skin cancers very rarely metastasize, approximately %5 of squamous cell skin cancers spread to regional lymph nodes and distant organs.

Basal cell skin cancer in particular tends to recur locally, and only one treatment is approved for advanced basal cell cancer (sonidegib); until now, no treatment had been approved for advanced squamous cell skin cancer.

Details of the Study Leading to FDA Approval of Cemiplimab, an Immunotherapy Drug Blocking PD-1

Cemiplimab, administered by intravenous infusion, targets the PD-1 pathway and is an immunotherapy that thereby helps the body's immune system fight cancer cells.

Cemiplimab (Libtayo) is the 6th different PD-1 / PD-L1-targeting immune checkpoint inhibitorto receive FDA approval for treating various cancers. The others are nivolumab (Opdivo), pembrolizumab (Keytruda), atezolizumab (Tecentriq), avelumab (Bavencio) and durvalumab (Imfinzi).

Cemiplimab's safety and efficacy were evaluated in two open-label clinical trials; the efficacy assessment included 75 patients with metastatic disease and 33 with locally advanced squamous cell skin cancer, a total of 108.

Approximately half of patients treated with cemiplimab (% 47.2) had an objective response, the study's primary endpoint. Most responses were ongoing at data analysis.

During cemiplimab treatment, the most commonly reported immunotherapy side effects were skin allergies, fatigue and diarrhea. As with other immunotherapies, the drug may cause serious or life-threatening reactions. These include pneumonitis, colitis, hepatitis and endocrinopathies, as well as dermatological and kidney problems, with risks related to the immune system mediating these side effects.

Libtayo is administered by intravenous infusion every three weeks until disease progression or unacceptable side effects occur. We consider this FDA approval highly meaningful for advanced squamous cell skin cancer, which had no approved treatment.