An interim analysis for futility will be conducted after 24 evaluable patients have been accrued assuming that the time between accrual of the first patient and accrual of the 24th patient is at least 8 months. If 24 patients are accrued in less than 8 months, accrual will continue until the time period between the date of accrual of the first patient and the date of accrual of the last patient is at least 8 months. If the trial is not terminated for futility after the interim analysis, an additional 10 patients will be accrued for a total of 34 patients. The two-stage design minimizes the expected duration of accrual under the null hypothesis.