Success after a century of failures: Inside Moderna and Merck’s cancer vaccine breakthrough

On August 13, CEO Stephane Bancel of Moderna received a phone call late at night while he was at a Lebanese restaurant celebrating a friend's birthday. The news was groundbreaking: the company's mRNA cancer vaccine, developed in partnership with Merck, had successfully entered late-stage testing after a century of failed attempts.

This marked the first therapeutic cancer vaccine to demonstrate efficacy in human trials. Experts hailed the achievement as the beginning of a new era of personalized vaccines that could train the immune system to specifically target an individual patient's cancer. Trials involving over 1,000 patients with localized melanoma showed the vaccine prevented tumors from recurring or spreading.

The stock market reacted positively, predicting billions of dollars in potential sales. Bancel compared this moment to the announcement of Moderna's COVID-19 vaccine in late 2020, emphasizing the significance of the breakthrough for global health. However, the initial joy quickly gave way to the realization of the extensive work ahead.

Merck's President Dean Li and head of global clinical development, Eliav Barr, immediately began preparing data for presentation at an international cancer meeting, addressing the U.S. FDA review process, and applying the study's findings to other ongoing trials. Ten years of collaboration between Merck and Moderna culminated in this significant milestone, with Merck investing $200 million upfront in 2016 and an additional $250 million in 2022.

The partnership aimed to build upon Merck's Keytruda, a powerful checkpoint inhibitor drug that unleashes the immune system to fight cancer. Despite initial failures with other cancer vaccines, the companies turned to mRNA technology and genomic sequencing to develop a vaccine that targeted multiple mutations unique to each patient's tumors.

With this personalized approach, the vaccine provided 34 patient-specific cancer targets, with at least one needed to be effective. The potential approval of the vaccine could come as early as next year, presenting a major opportunity for both companies amid changing market dynamics. Merck faces patent expiration of Keytruda, its top-selling drug, while Moderna seeks to capitalize on the success of its COVID-19 vaccine and regain market share.

Analysts predict sales of the vaccine could surpass $1 billion by 2030 and $3 billion by 2035. However, the next challenge lies in determining whether the approach can be effective in cancers with fewer mutations, such as lung, kidney, and pancreatic cancers.