Neon Therapeutics Inc. said the European Patent Office revoked a patent related to its neoantigen product candidates following opposition from multiple parties, including one from Gritstone Oncology Inc.

Cambridge, Mass.-based Neon, which completed its $100 million IPO on Nasdaq in July, said it will appeal the decision against its European patent which is numbered 2569633. While the appeal is pending at the European Patent Office, the patent remains effective and enforceable.

The biotechnology company develops therapies that target neoantigens — abnormal proteins produced by cancer cells — and personalized T cell therapies. One of these therapies is the NEO-PV-01 neoantigen vaccine, which, in combination with Bristol-Myers Squibb Co.'s Opdivo, or nivolumab, is being studied to treat skin cancer, non-small cell lung cancer and bladder cancer.

Another neoantigen vaccine called NEO-SV-01 is being studied to treat a type of breast cancer. Neon also has a strategic collaboration with CRISPR Therapeutics AG.

Neon said it will continue to pursue additional European patent filings in support of its product candidates.