U.S. drugmaker Bristol Myers Squibb announced Monday a $1.5 billion upfront payment to partner with Germany's BioNTech on an experimental cancer drug, in a deal that could eventually exceed $11 billion in value for BioNTech.

Bristol said it will co-develop and co-commercialize BioNTech's drug, BNT327, for multiple solid tumor types.

The drug belongs to a class of next-generation immunotherapies - which harness patients' immune systems to target and fight disease - called bispecific antibodies. BNT327 targets 2 proteins, PD-L1 and VEGF-A.

"We are impressed by the innovation that BioNTech has achieved to date and we look forward to partnering to accelerate existing clinical trials and time to market, while expanding the number of potential indications," Bristol Myers CEO Chris Boerner said in a statement.

In addition to the initial payment, Bristol plans to pay BioNTech up to $2 billion more in non-contingent anniversary payments through 2028. BioNTech may also earn up to $7.6 billion more in development, regulatory and commercial milestones, Bristol said.

The companies will share global profits and losses from the drug equally, and joint development and manufacturing costs will also be shared on a 50/50 basis, subject to some exceptions.

BNT327 is currently being tested as a first-line treatment in extensive stage small cell lung cancer and non-small cell lung cancer. More than 1,000 patients have been treated with the drug to date.