An example of pre-FDA-approval financing is Royalty Pharma's "adaptive financing" for Sunesis Pharmaceuticals lead product candidate, Vosaroxin. At the time, Vosaroxin was being evaluated in a Phase-III, randomized, double-blind, placebo-controlled trial among patients with first relapsed or refractory acute myeloid leukemia (AML).

Suppose, given a 2.5% significance level threshold for a one-tailed Z-test, the trial was designed to have a 90% probability of detecting a 2-month increase in overall survival among patients in the study. If the treatment response standard deviation was 6.5 months and there are an equal number of patients in each arm of the study, then how many patients would the study require in total? Assume that treatment responses are independent and identically distributed given the treatment arm. Therefore, by the central limit theorem, the average treatment response in each arm can be estimated by a normal distribution.

(Note: Your answer should be the total number of patients in the trial, NOT the number of patients in each arm.)