I was reading this short report (our BAT friends are involved) thinking it showed real promise for C, then in conclusion they say no. Agreed the p values are high, the CIs are wide, but the results were so lopsided that to me it merely means the trial was underpowered and C is worth a try.
High-Dose Intravenous Vitamin C Combined with Docetaxel in Men with Metastatic Castration-Resistant Prostate Cancer: A Randomized Placebo-Controlled Phase 2 Trial. July 31, 2024
High-dose intravenous vitamin C(HDIVC) administered to produce pharmacologic concentrations shows promise in preclinical models and small clinical trials, but larger prospective randomized trials are lacking. We evaluated the clinical benefit of combining HDIVC with docetaxel in patients with progressive metastatic castration-resistant prostate cancer(mCRPC).
This double-blind, placebo-controlled phase 2 trial randomized 47 patients 2:1 to receive docetaxel(75mg/m2 IV) with either HDIVC(1g/kg) or placebo. Co-primary endpoints were PSA50 response and adverse event rates. Secondary endpoints included overall survival, radiographic progression-free survival(rPFS), and quality-of-life measured using the Functional Assessment of Cancer Therapy-Prostate(FACT-P) instrument. Correlative analyses included pharmacokinetics and oxidative stress markers.
Eighty-nine percent of patients previously had 3 or more lines of therapy. PSA50 response rate was 41% in the HDIVC group and 33% in the placebo group(p=0.44), with comparable adverse event rates in both groups. There were no significant differences in FACT-P scores. Median rPFS was not significantly different between the HDIVC and placebo groups, with durations of 10.1 and 10.0 months(HR:1.35; 95%CI, 0.66-2.75, p=0.40). Median overall survival was 15.2 months in the HDIVC group and 29.5 in the placebo group(HR:1.98; 95%CI, 0.85-4.58, p=0.11). HDIVC did not decrease F2-isoprostanes, indicators of oxidative stress. The study was suspended after pre-specified interim analysis indicated futility in achieving primary endpoints.
In this patient population, combining HDIVC with docetaxel did not improve PSA response, toxicity, or other clinical outcomes compared to docetaxel alone. Findings do not support the routine use of HDIVC in mCRPC treatment outside of clinical trials.
