Combination therapies are increasingly used in areas such as oncology and immunology, and their relevance is expected to grow further in the future. These therapies combine two or more drugs to achieve an improved clinical outcome in a particular indication. Frequently, these products come from different manufacturers, with one supplying the "backbone" therapy and the other the "add‑on" component. To facilitate market access, manufacturers may wish to coordinate certain market access activities. However, where these manufacturers are actual or potential competitors (e.g., with respect to the combined products), such coordination may give rise to antitrust risks.

Under EU competition law, the exchange of competitively sensitive information (CSI) between competitors can raise significant concerns. This is especially true for current or future price‑related information, which competition authorities consider highly sensitive because it reduces strategic uncertainty in the market. This raises the question if, and to what extent, manufacturers can cooperate in their market‑access activities for combination therapies, as market access typically touches on prices or other forms of CSI (e.g., cost, budgets, etc.).

Competition authorities have started to acknowledge this challenge. The UK Competition and Markets Authority issued guidance in 2023, followed by the Belgian Competition Authority in 2025. Both recognize that market access for combination therapies can involve antitrust risks and provide guidance to manage these risks. However, their guidance is restricted to the respective national reimbursement systems and offers limited direction beyond those jurisdictions.

Even with the new EU HTA Regulation having entered into application, substantial differences persist between national reimbursement systems in the EU. Consequently, what information can be shared from an antitrust perspective varies. Where cooperation is required for regulatory reasons, competition law is generally not a barrier to information exchange; otherwise, the permissibility of information exchange depends in particular on the strategic relevance of the information in the context of the specific national reimbursement system.

To ensure compliance with EU competition law during market access for combination therapies, manufacturers should consider the following recommendations:

• Address antitrust considerations early in the planning of market access for combination therapies (e.g., at the stage of co‑sponsored clinical trials).
• Ensure that coordination is governed by a clear contractual framework ("cooperation agreement") that has been assessed from an EU competition law perspective.
• Implement safeguards such as clean teams or firewalls if necessary to prevent the unlawful exchange of CSI.
• Ensure close coordination between Legal and Market Access teams throughout the execution of the cooperation.

To navigate varying antitrust challenges across the different national reimbursement systems in the EU, manufacturers should monitor guidance issued by national competition authorities and seek practical competition law advice where needed.