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Issue 333: Our new pre-print updates on an ongoing adaptive therapy trial for men with castrate-sensitive prostate cancer. Median time to progression has not yet been reached, but 6 of 16 patients have progressed. We focus on identifying biomarkers that may predict these early progressors after just one on-off cycle of treatment. We identify significant features in the dynamics of testosterone and prostate-specific antigen (PSA). A higher average PSA-to-testosterone ratio, which crucially couples the tumor growth to its resource, is identified as a potential biomarker for early progression. Further, fitting a mechanistic mathematical model to the first cycle suggests progressors have a more pre-existing resistance. We illustrate the actual patient data from the first cycle graphically, with time normalized by the cycle duration. On the left, the PSA dynamics are in the numerator, and testosterone dynamics are in the denominator. Their ratio is on the right. The earliest progressors are colored red and thicker and the later progressors are yellow and thinner, which transitions to the gray, dotted thin-lined nonprogressors.