Background: Early phase cancer clinical trials involve experimental drugs with novel mechanisms of action. The primary aim of these studies is to determine safety and dosage of these novel therapeutics. Multiple retrospective studies in early phase trial centres outside of Australia but there is limited data on phase 1 trial outcomes in Australian centres conducting early phase trials. Toxicity is a key concern for patients considering enrolling in early phase cancer clinical trials due to the degree of uncertainty and there is a paucity of local data to support these conversations.
Methods: We conducted a retrospective audit of all patients treated in the Phase 1 trials unit at Liverpool Hospital between 2013 and 2023. Clinical, pathological and survival data was collected for all patients. The project was approved by the Sydney South West Local Health District Human Resources and Ethics Committee.
Results: 235 patients across 40 early phase clinical trials were included in the study. Median age was 65 years (range 31 – 81 years). Majority of patients were male (n=129) whilst almost 50% were active or ex-smokers (n=117). Most patients had an Eastern Cooperative Oncology Group (ECOG) score of 1 at baseline (n=129) with median number of 2 medical comorbidities at baseline and median number of 2 sites of metastatic disease. The median number of cycles of treatment completed was 2. Median time from consent to commencement of the trial was 13 days (range 1- 82 days). Most patients discontinued their trials due to disease progression (n=170, 72%). Median overall survival was 11.7 months in the entire cohort. Toxicity due to early phase trials was low with only 6% (n=15) discontinuing the study due to toxicity associated with trial protocols. No deaths occurred secondary to trial-related toxicity. Less than 5% of study participants (4.2%) experienced a serious adverse event leading to hospitalisation as a result of their study.
Conclusions: Early phase clinical trials are an important part of the drug development process and NSW has a large and rapidly growing early phase trials sector. Our retrospective audit reveals a relatively low toxicity burden at our institution, consistent with international data showing that early phase trials remain a relatively safe activity. Novel therapeutics go through extensive preclinical testing and there are stringent safety monitoring requirements that protect participant safety.