Poster Presentation 2025 Joint Meeting of the COSA ASM and IPOS Congress

Observations of lenvatinib dosing variability at a single centre: a case for therapeutic drug monitoring (124616)

Jin Quan Eugene Tan 1 2 3 , Natansh D Modi 1 4 , Ramin Hassankhani 3 5 , Helen Martin 2 , Madele van Dyk 5 , Shane Spencer 5 , Benedetta C Sallustio 5 6 , Ganessan Kichenadasse 1 3
  1. College of Medicine and Public Health, Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia
  2. SA Pharmacy, SA Health, Adelaide, South Australia, Australia
  3. Department of Medical Oncology, Flinders Medical Centre, Adelaide, South Australia, Australia
  4. Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia
  5. Department of Clinical Pharmacology, The Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, Adelaide, South Australia, Australia
  6. Discipline of Pharmacology, School of Biomedicine, The University of Adelaide, Adelaide, South Australia, Australia

Purpose: Lenvatinib is an oral multi-kinase inhibitor approved in Australia for renal cell carcinoma (RCC), endometrial cancer (EC), hepatocellular carcinoma (HCC), and radioactive iodine-refractory differentiated thyroid cancer (DTC). For RCC and EC, lenvatinib (20 mg/day) is combined with pembrolizumab, while for DTC and HCC it is used as monotherapy—24 mg/day for DTC, and weight-based dosing for HCC (8 mg/day if <60 kg; 12 mg/day if ≥60 kg). Studies have demonstrated an exposure–response relationship for lenvatinib. However, it is often poorly tolerated in real-world settings, with over 60% of patients requiring dose reductions or interruptions. These issues have prompted interest in therapeutic drug monitoring (TDM) as a means to optimise dosing and improve outcomes. This single-centre study reviews lenvatinib dosing practices across cancer types and discuss the potential role of TDM. 

Methods: Medical records from Flinders Medical Centre, a public hospital in South Australia, were retrospectively reviewed for patients treated with lenvatinib for cancer indications between December 1, 2016, and December 31, 2023. Data on cancer diagnoses, lenvatinib dose, and demographics were collected and analysed.

Results: Eighteen patients (19 treatment episodes), median age 61 years (range: 34–79), received lenvatinib. Cancer types included DTC (n=10), EC (n=4), HCC (n=3), RCC (n=1), and adenoid cystic carcinoma (n=1). Lenvatinib was started at a reduced dose in 42% of the treatment episodes, and of these episodes 90% were never escalated to the recommended dose. At least one adverse event related to lenvatinib was reported in 95% of all treatment episodes during the study period.

Conclusion: This study suggests clinicians diverge from guideline-recommended lenvatinib dosing. Even with initial dose reductions, adverse events and treatment interruptions still occur. These findings support the need for individualised approaches, such as TDM, to optimise dosing. Future studies should define target lenvatinib concentrations across cancer types to improve treatment outcomes.