A phase II study investigating biological effects of maintenance usage of hydroxychloroquine on Par-4 levels in patients with resected tumors

3085 Background: Hydroxychloroquine (HCQ) is an inducer of the tumor suppressor Par-4 (prostate apoptosis response-4) secretion from normal cells. Secreted Par-4 causes paracrine apoptosis of tumor cells in mice. Established dosing of HCQ 200 mg bid induces Par-4 secretion but not the autophagy-inhibition marker p62 and correlates with apoptosis induction in patients' tumors. Methods: This is a single-arm, single institute phase II study to characterize the biological effects of 3-months of HCQ at fixed-dose (200 mg p.o. twice a day) on plasma Par-4 levels in adults with resected solid tumors. The primary endpoint is proportion of patients who will exhibit a two-fold increase in Par-4 levels from baseline compared to 3 months of follow-up. 12-month progression free survival (PFS) is one of the secondary endpoints. A Simon's two-stage design was used to test the null hypothesis that the proportion of patients exhibiting a two-fold increase in Par-4 is equal to 50% compared to 70% using a one-sided alternative. These hypothesized assumptions are based on a small pilot human data and from a phase I clinical trial on a small number of patients (n = 9). The first stage of interim analysis will be performed after a total of 15 patients have been accrued. If there are eight or fewer responses occurred, the study will be stopped. Otherwise, 28 additional patients will be accrued for a total of 43 subjects. Results: A total of 19 patients were enrolled in the trial. Per protocol, the interim analysis and stopping boundary is based on the first 15 patients. A total of 4 out of 15 patients (26.7%) 95% CI: 8% - 55% exhibited a >2-fold increase in Par-4 levels at 3 months. This did not surpass the stopping bound for futility and thus indicates stopping of patient accrual based on the assumptions used for the Simon's two-stage design. 7 out of 19 patients (36.8%) 95% CI: 16% - 62% who exhibited at least a 2-fold increase at either 2 or 3 months of follow-up, 50% (95% CI: 26% - 74%) and 56% (95% CI: 31% -79%) exhibited a 1.5-fold and 1.25-fold increase respectively. To date, 10/19 patients finished 12-month follow-up, 4/19 and 5/19 finished 6-month and 3-month follow up respectively. 2 of 12 patients with less than 2-fold increase of Par-4 developed disease progression. None of 7 patients with 2-fold increase of Par-4 showed disease progression. Conclusions: Despite that the study was terminated prematurely, to our knowledge this is the first study in human to identify dynamic changes of serum Par-4 while on long-term of usage of HCQ. We also demonstrate trend of PFS benefit especially for subjects having 2-fold increase of Par-4 induction. Identification of tumors more Par-4 sensitive and predictive biomarkers of Par-4 induction are necessary to continue our investigation. Clinical trial information: NCT02232243.