On June 3, 2016 CellAct Pharma, a developer of innovative treatments for cancer, reported that population pharmacokinetic (PK) data from a phase 2 study of CAP7.1 supports efficacy findings in biliary tract cancer patients. CAP7.1 is a newly designed prodrug of the well-established anticancer agent etoposide, converted by carboxylesterases into etoposide in selected tissues (Press release, CellAct Pharma, JUN 3, 2016, View Source [SID:1234512981]). Analysis of the population PK indicated higher blood concentrations of etoposide resulted in the majority of patients maintaining an increase in tumor size below 20%. Data were published in conjunction with the 52nd Annual Meeting of the American Society for Clinical Oncology (ASCO) (Free ASCO Whitepaper) in Chicago (Abstract e15602).

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"Population pharmacokinetics is an important consideration in the drug development process as it helps to explain the variable effects of certain inter patient characteristics, such as age, body weight and co-medication, can have on a drug’s efficacy and safety. The data presented at ASCO (Free ASCO Whitepaper) will help in determining a standard dosing regimen for CAP7.1," explained Nalân Utku, MD, PhD, MDRA, Chief Executive Officer of CellAct Pharma. "These population PK data provide additional support to the results from our Phase 2 with CAP7.1, where encouragingly, planned interim analysis showed that more than half of therapy refractory, advanced stage biliary tract cancer patients met the primary objective of disease control, as presented at the ASCO (Free ASCO Whitepaper) GI Meeting in San Francisco."

Study Details

Data for the population PK model was analyzed from a total of 434 observations taken from 39 patients from Phase 1 and 2 studies. Using PK modeling software, etoposide AUC0-24h, cmax and cmin for each biliary cancer patient were simulated and compared with the individual changes in total target lesion (TTL) size. A higher AUC0-24h was found to be associated with a lower increase in TTL size (R2=0.172). Out of all patients for which PK information was available, 50% maintained a TTL size increase below 20%. This compared to 80% of patients with an 24hAUC > 120 h ug/mL who maintained a TTL size increase below 20%. Similarly, a higher cmax (R2=0.177) or cmin (R2=0.11) were associated with a larger effect on TTL size.