Phase I Study of High-Dose Intravenous Vitamin C in Advanced Cancer:
Safety and Dose Exploration
One important area of research into high-dose intravenous vitamin C (intravenous ascorbic acid) in cancer has been to determine whether pharmacological concentrations can be achieved safely in patients with advanced disease before exploring potential clinical value.
The main purpose of this Phase I study was not to prove that vitamin C could control cancer, but to evaluate the safety, tolerability, and pharmacokinetic characteristics of different intravenous doses.
What Did the Study Do?
The study enrolled 24 patients with advanced solid tumours or haematological malignancies. Most had previously received cancer-related medical care.
24
Participants
Patients with Advanced Solid Tumours or Haematological Malignancies
This was a population with advanced disease, and most participants had already undergone previous cancer-related medical care.
The study focused on adverse events, tolerability, and changes in plasma ascorbate concentrations across different intravenous dose levels.
How Were Different Doses Explored?
Participants were assigned to different dose groups and received intravenous ascorbic acid three times per week. This allowed the investigators to assess how increasing doses affected safety, tolerability, and pharmacokinetics.
0.4 g/kg
0.6 g/kg
0.9 g/kg
1.5 g/kg
Three Times per Week
Adverse Event Monitoring
Pharmacokinetics
What Did the Study Observe?
Across the tested dose levels, adverse events and toxicity were relatively limited overall, and high-dose intravenous ascorbate showed a degree of tolerability in this group of patients.
Reaching Pharmacological Concentrations Does Not Prove Clinical Benefit
High plasma concentrations demonstrate the pharmacokinetic properties of intravenous administration. They do not, by themselves, prove tumour control or a survival benefit for patients.
~26 mM
Peak Plasma Concentration at the Highest Dose
1.5 g/kg Could Produce Millimolar Pharmacological Concentrations
Plasma ascorbate concentrations increased markedly as the intravenous dose increased.
At the highest dose of 1.5 g/kg, later pharmacokinetic summaries of the study reported peak plasma concentrations of approximately 26 mM, further demonstrating that intravenous administration can produce concentrations far above those typically achieved with conventional oral supplementation.
Were Any Objective Antitumour Responses Observed?
0
No Patient Demonstrated an Objective Antitumour Response
In other words, this study supports the conclusion that high-dose intravenous vitamin C showed a degree of tolerability under the study conditions and could achieve high plasma concentrations. It did not demonstrate that intravenous vitamin C used alone had a definite tumour-control effect.
How Should This Study Be Interpreted?
This was a Phase I dose-escalation and pharmacokinetic study. The role of a Phase I trial differs from that of later-stage studies designed primarily to determine clinical efficacy.
Can the intervention be given safely under study conditions?
Can patients tolerate the different dose levels?
What blood concentrations are produced at different doses?
Are there adverse effects that limit further dose escalation?
Acceptable Safety and Clinical Effectiveness Are Different Questions
The absence of an objective tumour response does not mean that all further investigation has no value. Equally, acceptable tolerability in an early safety study does not establish a definite anticancer effect.
The authors themselves reached a cautious conclusion: high-dose intravenous ascorbic acid was generally well tolerated in these previously treated patients with advanced malignancy, but ascorbate used alone did not demonstrate antitumour activity.
The authors therefore suggested that future investigation might more appropriately examine intravenous ascorbate in combination with cytotoxic agents or other redox-active approaches.
What Did This Study Contribute to Later Research?
One of the study’s important contributions was the provision of human dose and pharmacokinetic data for high-dose intravenous ascorbic acid.
High Plasma Concentrations Were Achievable
Intravenous administration could produce millimolar concentrations of ascorbate in humans, establishing a research context distinct from routine oral supplementation.
Dose and Safety Data Were Established
The study provided further human clinical information on tolerability, adverse events, and drug exposure across different weight-based doses.
It Supported Later Combination Research
Subsequent studies increasingly explored the safety and feasibility of high-dose intravenous vitamin C alongside chemotherapy or other cancer-care approaches.
The National Cancer Institute (NCI) also includes this Phase I trial among the important human clinical studies reviewed in relation to intravenous vitamin C and cancer.
However, current evidence does not support using high-dose intravenous vitamin C as a replacement for standard cancer care.
How Does BMS Clinic View This Evidence?
This study highlights that high-dose intravenous vitamin C should be regarded as a high-dose intravenous medical intervention requiring appropriate monitoring, rather than as routine vitamin supplementation.
Before this type of medical support is considered, assessment should take into account the patient’s current cancer status, previous and ongoing medical care, kidney function, G6PD status, electrolyte balance, and other individual risk factors.
BMS Clinic emphasises professional assessment based on current medical evidence and individual circumstances. If high-dose intravenous vitamin C is considered, it should be evaluated alongside the patient’s existing cancer-care plan, and a Phase I safety study should not be interpreted as proof of established clinical efficacy.
This page is provided for medical education and literature information purposes only. It is intended to help readers understand an early Phase I study of high-dose intravenous vitamin C in patients with advanced cancer and does not replace diagnosis, assessment, or personalised medical advice from a qualified healthcare professional.
The study discussed primarily evaluated the safety, tolerability, and pharmacokinetics of high-dose intravenous ascorbic acid and was not designed to establish efficacy against cancer. No objective antitumour responses were observed; therefore, the findings do not demonstrate that high-dose vitamin C can control cancer, reduce tumour size, or prolong survival.
Patients with cancer considering high-dose intravenous vitamin C or other supportive medical approaches should first undergo appropriate medical assessment based on their individual condition, current cancer care, kidney function, G6PD status, and other relevant risk factors.
Learn More About High-Dose Intravenous Vitamin C Support
This Phase I study primarily provides information on the safety, tolerability and dose-related characteristics of high-dose intravenous vitamin C, and did not establish clear tumour-control activity when used alone. Anyone considering this type of medical support should first undergo professional assessment based on their cancer status, current medical care, kidney function, G6PD status and other individual risk factors.
References
Hoffer LJ, Levine M, Assouline S, et al. Phase I clinical trial of i.v. ascorbic acid in advanced malignancy. Ann Oncol. 2008;19(11):1969–1974.
National Cancer Institute. Intravenous Vitamin C (PDQ®) – Health Professional Version. National Cancer Institute.
National Cancer Institute. Intravenous Vitamin C (PDQ®) – Health Professional Version. National Cancer Institute.