Bowman-Birk Inhibitor Concentrate in Preventing Cancer in Patients With Oral Leukoplakia

OBJECTIVES:

Primary

- Determine if chemoprevention by the Bowman-Birk inhibitor concentrate (BBIC) can
prevent cancer in patients with oral leukoplakia (OL).

- Determine the clinical and histologic response rate of OL to BBIC.

Secondary

- Measure the effect of BBIC on intermediate marker endpoint levels.

- Correlate the clinical and histologic responses of OL with cellular levels of
proteolytic activity, erb-B2 (neu), retinioc acid receptor β, bcl-2, and mutant p53
expression, and serum levels of neu.

- Determine the individual and group side effects of BBIC.

OUTLINE: This is a multicenter, randomized, double-blind, placebo-controlled, study.

Prior to randomization, all patients receive oral placebo for 4 weeks. Patients who show
good compliance (> 75% packet count) are randomized to 1 of 2 treatment arms.

- Arm I: Patients receive oral Bowman-Birk inhibitor concentrate twice daily for 6 months
in the absence of disease progression or unacceptable toxicity.

- Arm II: Patients receive oral placebo twice daily for 6 months in the absence of
disease progression or unacceptable toxicity.

Patients complete questionnaires about diet, tobacco, and alcohol usage at baseline and at
the completion of study treatment.

Blood, urine, and biopsy tissue are collected at baseline and at the completion of study
treatment. Oral mucosal cells are collected at baseline, during the run-in phase, at
randomization, after completion of study treatment, and at 3 months after completion of
study treatment. Samples are examined for protease activity, levels of bcl-2 and erbB-2,
mutant p53 oncogene expression and epidermal growth factor receptor, and retinoic acid
receptor-β expression.

After completion of study treatment, patients are followed at 3 months.

PROJECTED ACCRUAL: A total of 210 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

- Histologically and clinically confirmed oral leukoplakia and/or erythroplakia

- Bidimensionally measurable disease (≥ 100 mm^2 for total area of all lesions) after
biopsy

- No presence of obvious head and neck aerodigestive tract cancer, carcinoma in situ,
or previously treated head and neck cancer within the past 2 years

PATIENT CHARACTERISTICS:

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No history of allergic reaction to soybeans, sorbitol, sucrose, artificial
flavorings, aspartame, saccharin, or lidocaine

PRIOR CONCURRENT THERAPY:

- At least 6 months since prior Bowman-Birk inhibitor concentrate

- At least 6 months since prior participation in another randomized clinical trail

- At least 3 months since prior systemic steroids or topical oral steroid preparations

- Topical nasal steroid sprays or cutaneous preparations with minimal systemic
absorption for nasal or dermatologic disorders allowed

- More than 6 months since prior beta carotene capsules

- At least 2 years since prior retinoid or other beta carotene therapy, including >
25,000 IU of vitamin A for any reason

- Up to 2 multivitamins per day allowed