# Measure blood levels of oral targeted drugs and adjust doses to a target range

Source: https://onco.cc/ideas/idea-tr1-therapeutic-drug-monitoring-for-oral-tkis/  
OnCo record `idea-tr1-therapeutic-drug-monitoring-for-oral-tkis` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Blood levels of oral cancer pills vary several-fold between people on the same dose, so some are under-treated and others poisoned. Checking levels and adjusting the dose, as is routine for some antibiotics, could fix both.

## Summary

Therapeutic drug monitoring (TDM) for oral kinase inhibitors and hormonal agents with established exposure-response relationships and high inter-patient variability (imatinib, sunitinib, pazopanib, abiraterone, tamoxifen via endoxifen, and newer agents), with dose adjustment to a target trough. Dutch multicentre TDM studies have shown feasibility and increased target attainment; outcome-powered randomised trials are lacking.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: TDM-guided dosing will increase the proportion of patients within the target exposure range from roughly half to over 80 percent and will improve PFS or reduce grade 3+ toxicity relative to fixed dosing in a randomised comparison.
- Rationale: Adherence, food, interactions and pharmacogenetics cause large exposure variability; fixed dosing ignores it. TDM is standard for narrow-therapeutic-index drugs in other fields.
- Proposed test: A randomised trial of TDM-guided versus fixed dosing for two or three TKIs with the strongest exposure-response evidence, with PFS and toxicity endpoints.
- Maturity: early-clinical
- Actor: clinic

## Sources

- Bottleneck evidence (Wrong doses): FDA Oncology Center of Excellence, Project Optimus: https://www.fda.gov/about-fda/oncology-center-excellence/project-optimus

## Connected records

- technologies: [Endocrine therapy (SERMs, AIs, SERDs)](https://onco.cc/technologies/endocrine-therapy/), [Small-molecule kinase inhibitors](https://onco.cc/technologies/kinase-inhibitors/)
- drugs: [Imatinib](https://onco.cc/drugs/imatinib/)
- bottlenecks: [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/), [Wrong doses](https://onco.cc/bottlenecks/b-dose-optimisation/)

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