The Contribution to the Assignment of Defined Daily Dose (DDD) to Antineoplastic Drugs of the Italian Working Group on DDD

Purpose: To report the experience of the Italian Working Group on DDD (Ita-DDD-wg) in assigning DDDs to a list of antineoplastic agents. Methods: Active substances from the ATC L01 group with no assigned DDD and reimbursed at least once during 2021 by the Italian Healthcare Service were identified. A DDD-assignment reporting template was developed, including the following fields: ATC fifth-level code, active substance, route of administration, reference indication of use, reference posology, assignment criteria, DDD calculation formula, DDD value, and DDD unit of measure. Information from national and international Summaries of Product Characteristics of medicines containing the active substance of interest, along with evidence from literature and input from Ita-DDD-wg experts, were considered. DDD assignment criteria were based on ATC/DDD guidelines and, whenever necessary, complemented by ad hoc criteria. Results: Forty-three ATC 5th-level codes were evaluated, resulting in a total of 44 DDDs assigned (2 distinct DDDs were assigned respectively to topical and oral aminolaevulinic acid formulations). For 35 out of 44 DDDs, adaptations of general WHO assignment criteria or newly defined approaches were adopted, that is, calculations based on reference body surface area (BSA = 1.82 m2), treatment cycle duration, and average daily amounts of topical product. Conclusion: This work demonstrated that assigning DDDs to antineoplastic agents is feasible based on few additional assumptions and criteria with respect to those from ATC/DDD guidelines. In fact, based on this work, WHO decided to establish an ad hoc working group for evaluation and assignment of DDDs to antineoplastic agents.