Randomized trial of intrapatient dose escalation of single agent carboplatin as first-line treatment for advanced ovarian cancer: An SGCTG study (SCOTROC 4)

<b>Background:</b> In the absence of toxicity, carboplatin (the most widely used drug in ovarian cancer) is generally given at the same (flat) dose with each treatment cycle. However, retrospective data suggest a correlation between extent of myelosuppression and outcome, as has been observed in other diseases. Our hypothesis was therefore that intrapatient dose escalation, according to nadir blood counts, could lead to an improved outcome compared to conventional flat dosing. <b>Methods:</b> Patients with previously untreated stage IC to IV ovarian cancer were randomized to receive 6 cycles of carboplatin AUC 6 q3 w either with no dose modification except for toxicity (Arm A) or with dose escalations in cycles 2-6 based on nadir FBC (Arm B). The primary outcome measure was progression-free survival (PFS), and a target accrual of 1300 pts was envisaged, aimed at detecting a 20% increase in PFS with 80% power (5% 2-sided level of statistical significance). Results: From March 2004 to November 2008, 937 pts were recruited from 70 centres. Dose escalation occurred in 82% pts on Arm B. The median AUCs actually received were 6.0 (Arm A) and 6.84 (Arm B). As expected, more myelosuppression was seen in Arm B (p < 0.001 for all parameters). More grade 3/4 non-haematological toxicity was also seen in Arm B (31%, vs 22% in Arm A, p < 0.001) but there was no significant difference in global quality of life. To date, 477 PFS events have been observed out of a planned total of 950. The median PFS was 13.9m in Arm A, and 13.5m in Arm B, and the observed hazard ratio (Arm B/Arm A) is 1.04, with 95% C.I. of 0.87 to 1.24. This excludes the clinically relevant benefit of 0.83 used to design the study. A futility analysis also indicated that the probability of a statistically significant result in favour of Arm B at the planned study end was 0.12 at best. <b>Conclusions:</b> Following the Data Monitoring Committee recommendation, the trial has therefore been closed to recruitment, with no evidence of benefit for intra-patient dose escalation of carboplatin. A separate analysis of tissue samples, aimed at elucidating mechanisms of (single agent) carboplatin resistance is ongoing