Trial of Chemotherapy Plus Intravenous Vitamin C in Patients With Advanced Cancer for Whom Chemotherapy Alone is Only Marginally Effective

Cytotoxic chemotherapy is relatively ineffective for a large proportion of common cancers. Combining redox active molecules with certain chemotherapy regimens could increase their anti-cancer activity or protect host tissues from toxicity with no loss of anti-cancer activity. Research in this area has been advocated by cancer organizations, but previous clinical trials of combination chemotherapy and antioxidant therapy been small, poorly designed, and unsystematic. Appropriate study of this treatment concept requires a systematic, meticulous empirical approach similar to the one used in conventional cytotoxic drug discovery. This is a Phase I-II study designed to identify promising chemotherapy-antioxidant protocols and determine their acceptability and limiting toxicity in patients with relentlessly progressive cancers for which conventional chemotherapy is clinically indicated but is known to be minimally or marginally effective.

The tolerable dose of intravenous ascorbic acid (IVAA) for cancer patients with normal renal function not receiving chemotherapy is 1.5 g/kg per 90 to 120 minute infusion (Hoffer et al, Ann Oncol 2008;19:1969-1974). Side effects are minimal to non-existent. In this dose-escalating study the IVAA will be 0.9 g/kg per infusion for the first chemotherapy cycle, increasing to 1.5 g/kg per infusion in subsequent cycles, for the first 3 participants. If well tolerated as expected, the initial dose will be 1.5 g/kg per infusion for subsequent participants. Infusions will take place 2 or 3 times per week, bracketing the days of chemotherapy. Standard tolerance and adverse effect criteria will be used. Therapy will continue for a minimum of 2 months, and continue further in the event of disease stabilization or response, as determined from CT scan and biomarkers, with evaluations continuing every 2 months.

Inclusion criteria

• must be a resident of Quebec, Canada
• documented advanced or metastatic cancer or hematologic malignancy in adults over age 18, with measurable disease
• adequate bone marrow, hepatic, renal and cardiac function so as to permit conventional chemotherapy
• no current calcium oxalate nephrolithiasis with the potential to reduce urinary flow
• life expectancy at least 8 weeks.

Exclusion criteria

• glucose-6-phosphate dehydrogenase deficiency
• cancers for which existing chemotherapy offers more than a 33% likelihood of a clinically meaningful response
• serum creatinine greater than 175 micromol/L
• serious GI diseases
• infections
• recent major surgery
• dementia
• altered mental status or other condition that would preclude chemotherapy, including poor functional status.