Patent cliff crisis averted? Merck's (MRK.US) Keytruda subcutaneous version hits primary endpoint in phase 3 trial

Merck (MRK.US) on Tuesday unveiled a new formulation of its famous cancer therapy pembrolizumab (Keytruda), marking an important milestone for the company as its blockbuster intravenous version of Keytruda faces significant regulatory hurdles, with Keytruda generating $25bn in sales in 2023.

Merck said the subcutaneous version of the anti-PD1 drug met its primary endpoint in a key Phase 3 trial, matching the performance of the FDA-approved intravenous version and representing a first-line option for lung cancer.

While Wall Street's reaction was relatively muted, the development marks a key step in Merck's efforts to expand market access for the drug, which accounts for more than 40 per cent of the company's total sales.

Merck said it is preparing to submit applications for the new formulation to global regulators “as soon as possible”. For the New Jersey-based pharma giant, time is of the essence as Keytruda faces significant regulatory and market headwinds in the coming years.

As Merck loses US market exclusivity on the drug in 2028, a significant portion of its revenues will be at risk as competitors race to develop cheaper biosimilars, while the company can avoid this threat through the injectable version.

The injectable Keytruda contains Alteogen's drug delivery compound berahyaluronidase alfa, which will not be affected by competition in the short term, while the intravenous version faces biosimilars.

Moreover, the injectable Keytruda will be more convenient than the current version administered via intravenous infusion at infusion centres, which takes 30 minutes every three to six weeks.

Marjorie Green, Merck's head of oncology clinical development, said the new version of the drug takes about 2-3 minutes, “which could improve the patient experience and increase access for patients and healthcare providers compared to intravenous infusion”.