OBJECTIVES: To analyse the per-patient costs and potential savings of KANJINTI^® (an IV trastuzumab biosimilar) compared with originator Herceptin^® (SC and IV) and other trastuzumab biosimilars (IV) in HER2-positive early and metastatic breast (EBC/MBC) and metastatic gastric cancer (MGC) in Italy.

METHODS: Drug and administration costs were included. Official, public drug prices were used for Herceptin^® SC and IV, and a mandatory 20% discount was applied for all trastuzumab biosimilars. All IV trastuzumab formulations are available in 150-mg vials, whereas only KANJINTI^® would be available also in 420-mg vials. Drug costs were calculated for two scenarios: no vial-sharing and full vial-sharing (i.e. no drug wastage). For the no vial-sharing scenario, patient weight distributions by indication were implemented accounting for optimal vial combinations to minimise drug wastage.

RESULTS: KANJINTI^® was shown to generate savings ranging from €1,670 to €3,358 per patient vs. SC Herceptin^® across indications; €5,877 to €7,918 vs. IV Herceptin^®; and €958 to €1,236 vs. other trastuzumab biosimilars in the scenario with no vial-sharing. With full vial-sharing, KANJINTI^® would generate savings ranging from €4,300 to €5,761 per patient vs. SC Herceptin^®; €4,097 to €5,715 vs. IV Herceptin^®; and no additional savings vs. other trastuzumab biosimilars. With no vial-sharing, KANJINTI^® was the least costly treatment for EBC patients weighing 75 kg or less (60.25% of patients); with full vial-sharing, KANJINTI^® was the least costly treatment for EBC patients weighing 89 kg or lower (87.5%). Similar results were obtained for MBC and MGC patients.

CONCLUSIONS: KANJINTI^® is the least costly treatment option for the vast majority of patients, with the potential to realise budget savings compared with all other trastuzumab treatment options. The availability of the 420-mg vial allows a reduction of drug wastage and the generation of further savings with biosimilars when full vial-sharing is not possible.