Panitumumab (Vectibix) – Rare Cases of Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)

Last Updated on August 2, 2014 by Joseph Gut – thasso

May 27, 2014 – Health Canada informed us today that rare cases of Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) have been reported in patients treated with Panitumumab (Vectibix), and advises as follows:

• Cases of Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) have been reported rarely (≥1/10,000 patients and <1/1000 patients) in the post-market setting, in patients receiving VECTIBIX.
• The Product Monograph of Panitumumab (Vectibix) is being updated to include the risk of SJS and TEN.
• In case of the occurrence of SJS or TEN, Panitumumab (Vectibix) treatment should be discontinued.

Treating physicians need to monitor for dermatologic and soft tissue signs or symptoms and consider withholding or discontinuing Panitumumab (Vectibix) in patients with severe or life-threatening and inflammatory or infectious complications.

In Canada, Panitumumab (Vectibix) is indicated as monotherapy for the treatment of patients with epidermal growth factor receptor (EGFR)-expressing metastatic colorectal carcinoma with non-mutated (wild-type) KRAS after failure of fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.  Panitumumab (Vectibix) has been issued a marketing authorization with conditions (NOC/c), pending the results of studies to verify its clinical benefit.

Events such as skin exfoliation, exfoliative rash, erythema, skin necrosis and mucosal events such as stomatitis and mucosal inflammation have previously been reported with the administration of Panitumumab (Vectibix).  Serious complications that have been observed include events of cellulitis, necrotizing fasciitis (some with a fatal outcome), and other soft tissue complications

Panitumumab is a fully human monoclonal antibody specific to the epidermal growth factor receptor (also known as EGF receptor, EGFR, ErbB-1 and HER1 in humans).

Panitumumab was approved by the U.S. Food and Drug Administration (FDA) for the first time in September 2006, for the treatment of EGFR-expressing metastatic colorectal cancer with disease progression despite prior treatment. It was also approved by the European Medicines Agency (EMA) in 2007, and by Health Canada in 2008 for the treatment of refractory EGFR-expressing metastatic colorectal cancer in patients with non-mutated (wild-type) KRAS. It was also approved by Swissmedic in Switzerland. At the time, panitumumab was the first monoclonal antibody to demonstrate the use of KRAS as a predictive biomarker.

A copy of letter (announcement)  and the Canadian Product Monograph can be accessed at the Health Canada Web site. This information is also available at www.amgen.ca, the home of Amgen, the maker of Panitumumab (Vectibix).

Managing marketed health product-related adverse reactions depends on health care professionals and consumers reporting them. Reporting rates determined on the basis of spontaneously reported post-marketing adverse reactions are generally presumed to underestimate the risks associated with health product treatments. Any case of SJS or TEN, or other serious or unexpected adverse reactions, in patients receiving Panitumumab (Vectibix) should be reported to Amgen Canada Inc. or Health Canada.