Summary

This phase III trial studies how well vitamin D3 given with standard chemotherapy and bevacizumab works in treating patients with colorectal cancer that has spread to other parts of the body (advanced or metastatic). Vitamin D3 helps the body use calcium and phosphorus to make strong bones and teeth. Vitamin D3 may also modulate the immune system and is being studied in the prevention and treatment of some types of cancer. Chemotherapy drugs, such as leucovorin calcium, fluorouracil, oxaliplatin, and irinotecan hydrochloride, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Bevacizumab is a monoclonal antibody that binds to vascular endothelial growth factor (VEGF). VEGF is a substance made by cells that helps the formation of new blood vessels. Bevacizumab may prevent the growth of new blood vessels that tumors need to grow. Giving vitamin D3 with chemotherapy and bevacizumab may work better in shrinking or stabilizing colorectal cancer. It is not yet known whether giving high-dose vitamin D3 in addition to chemotherapy and bevacizumab would extend patients time without disease compared to the usual approach (chemotherapy and bevacizumab).

Objectives

PRIMARY OBJECTIVE:
I. To compare the progression-free survival (PFS) of patients receiving high-dose cholecalciferol (vitamin D3) in combination with standard chemotherapy (leucovorin calcium, fluorouracil, and oxaliplatin [FOLFOX] or leucovorin calcium, fluorouracil, and irinotecan hydrochloride [FOLFIRI]) and bevacizumab versus those receiving standard-dose vitamin D3 in combination with standard chemotherapy and bevacizumab.

SECONDARY OBJECTIVES:
I. To compare the objective response rate (ORR) of patients receiving high-dose vitamin D3 in combination with standard chemotherapy + bevacizumab versus those receiving standard-dose vitamin D3 in combination with standard chemotherapy + bevacizumab.
II. To compare the overall survival (OS) of patients receiving high-dose vitamin D3 in combination with standard chemotherapy + bevacizumab versus those receiving standard-dose vitamin D3 in combination with standard chemotherapy + bevacizumab.
III. To evaluate and compare the toxicity of adding high-dose vitamin D3 versus standard-dose vitamin D3 to chemotherapy + bevacizumab.
IV. To assess the influence of diet, body mass index, physical activity, and other lifestyle habits on PFS among patients with locally advanced/metastatic colorectal cancer.
V. To evaluate the incidence of vitamin D3 deficiency in participants with previously untreated metastatic colorectal cancer.
VI. To compare the efficacy of high-dose vitamin D3 versus standard-dose vitamin D3 in subgroups of patients defined by baseline plasma calcifediol (25[OH]D) levels, demographic and clinicopathologic characteristics.
VII. To evaluate the prognostic effect of highest-achieved 25(OH)D levels with PFS.

OTHER OBJECTIVE:
I. Results of the primary analysis will be examined for consistency, while taking into account the stratification factors and/or covariates of baseline quality of life (QOL) and fatigue.

EXPLORATORY OBJECTIVES:
I. To evaluate the association between germline variation in vitamin D pathway genes and plasma 25(OH)D levels, response to vitamin D3 supplementation, and patient outcome.
II. To evaluate the impact of high-dose vitamin D3 versus standard-dose vitamin D3 on the plasma angiome, and how the angiome modifies the association between vitamin D3 supplementation and patient outcome.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: Patients receive bevacizumab (or a Food and Drug Administration [FDA]-approved biosimilar) intravenously (IV) over 30-90 minutes on day 1 and oxaliplatin IV over 2 hours on day 1, leucovorin calcium IV over 2 hours on day 1, and fluorouracil IV on days 1-3 or irinotecan hydrochloride IV on day 1, leucovorin calcium IV over 90 minutes on day 1, and fluorouracil IV on days 1-3. Patients also receive high-dose cholecalciferol orally (PO) once daily (QD) on days 1-14. Cycles repeat every 14 days for 5 years in the absence of disease progression or unacceptable toxicity.

ARM II: Patients receive bevacizumab (or a FDA-approved biosimilar) and chemotherapy as in Arm I. Patients also receive standard-dose cholecalciferol PO QD on days 1-14. Cycles repeat every 14 days for 5 years in the absence of disease progression or unacceptable toxicity.

All patients undergo computed tomography (CT) or magnetic resonance imaging (MRI) throughout the trial. Patients may also undergo collection of blood on study.

After completion of study treatment, patients are followed every 6 months for 5 years.