How the cohort is important depends on whether the next cohort includes a higher dose or if it simply expands the number treated.
If there are AEs in Cohort 9, then Cohort 10 will be at the previous dose 210 mg/m2. If no AEs, then it will be at a higher dose likely to be close to or just over 500 mg/m2: 475 to 525. I doubt we will see another 66% bump.