Connecting lab, clinic, and community.

Despite great progress in biomedical research, the health of the US population appears to be getting worse. The United States spends substantially more per capita on health care than other wealthy countries, yet US life expectancy ranks low among its peers. Mortality rates have been increasing for segments of the US population, including those in rural areas, certain racial and ethnic groups, and individuals with low socioeconomic status. A whole-of-society approach is required to address such negative trends and disparities, and the biomedical research enterprise must play a key role.

An orientation to the US National Cancer plan for the research community.

The US National Cancer Act of 1971 designated the director of the National Cancer Institute as responsible for coordinating federal agencies and nonfederal organizations to make progress against cancer. As part of her role, the immediate past director of the National Cancer Institute (MMB) led the development of a National Cancer Plan that was formally released on April 3, 2023. The plan includes 8 aspirational goals "to achieve a society where every person with cancer lives a full and active life and to prevent most cancers so that few people need to face this diagnosis." Research findings provide a foundation for each goal, and research gaps are included in the strategies for meeting each goal. The President's Cancer Panel, also created by the National Cancer Act, conducted an initial assessment of progress toward the plan goals by hearing from 12 organizations at a virtual public meeting on September 7, 2023. The purpose of this commentary is to orient the scientific community to the plan and call attention to related knowledge gaps that could benefit from research.

15-Hydroxyprostaglandin dehydrogenase inactivation as a mechanism of resistance to celecoxib chemoprevention of colon tumors.

Pharmacologic inhibitors of the prostaglandin-synthesizing COX-2 oncogene prevent the development of premalignant human colon adenomas. However, resistance to treatment is common. In this study, we show that the adenoma prevention activity of the COX-2 inhibitor celecoxib requires the concomitant presence of the 15-hydroxyprostaglandin dehydrogenase (15-PGDH) tumor suppressor gene, and that loss of 15-PGDH expression imparts resistance to celecoxib's anti-tumor effects. We first demonstrate that the adenoma-preventive activity of celecoxib is abrogated in mice genetically lacking 15-PGDH. In FVB mice, celecoxib prevents 85% of azoxymethane-induced tumors >1 mm in size, but is essentially inactive in preventing tumor induction in 15-PGDH-null animals. Indeed, celecoxib treated 15-PGDH null animals develop more tumors than do celecoxib naive WT mice. In parallel with the loss of tumor prevention activity, celecoxib-mediated suppression of colonic PGE(2) levels is also markedly attenuated in 15-PGDH-null versus WT mice. Finally, as predicted by the murine models, humans with low colonic 15-PGDH levels also exhibit celecoxib resistance. Specifically, in a colon adenoma prevention trial, in all cases tested, individuals who developed new adenomas while receiving celecoxib treatment were also found as having low colonic 15-PGDH levels.

Celecoxib for the prevention of sporadic colorectal adenomas.

BACKGROUND: Studies showing that drugs that inhibit cyclooxygenase-2 (COX-2) reduce the number of colorectal adenomas in animals and patients with familial adenomatous polyposis suggest that COX-2 inhibitors may also prevent sporadic colorectal neoplasia. METHODS: We randomly assigned patients who had adenomas removed before study entry to receive placebo (679 patients) or 200 mg (685 patients) or 400 mg (671 patients) of celecoxib twice daily. Randomization was stratified for the use of low-dose aspirin. Follow-up colonoscopies were performed at one and three years after randomization. The occurrence of newly detected colorectal adenomas was compared among the groups with the life-table extension of the Mantel-Haenszel test. RESULTS: Follow-up colonoscopies were completed at year 1 in 89.5 percent of randomized patients, and at year 3 in 75.7 percent. The estimated cumulative incidence of the detection of one or more adenomas by year 3 was 60.7 percent for patients receiving placebo, as compared with 43.2 percent for those receiving 200 mg of celecoxib twice a day (risk ratio, 0.67; 95 percent confidence interval, 0.59 to 0.77; P<0.001) and 37.5 percent for those receiving 400 mg of celecoxib twice a day (risk ratio, 0.55; 95 percent confidence interval, 0.48 to 0.64; P<0.001). Serious adverse events occurred in 18.8 percent of patients in the placebo group, as compared with 20.4 percent of those in the low-dose celecoxib group (risk ratio, 1.1; 95 percent confidence interval, 0.9 to 1.3; P=0.5) and 23.0 percent of those in the high-dose group (risk ratio, 1.2; 95 percent confidence interval, 1.0 to 1.5; P=0.06). As compared with placebo, celecoxib was associated with an increased risk of cardiovascular events (risk ratio for the low dose, 2.6; 95 percent confidence interval, 1.1 to 6.1; and risk ratio for the high dose, 3.4; 95 percent confidence interval, 1.5 to 7.9). CONCLUSIONS: These findings indicate that celecoxib is an effective agent for the prevention of colorectal adenomas but, because of potential cardiovascular events, cannot be routinely recommended for this indication. (ClinicalTrials.gov number, NCT00005094 [ClinicalTrials.gov].).

Aberrant crypt foci in the adenoma prevention with celecoxib trial.

Aberrant crypt foci (ACF) are the earliest visible neoplastic lesions in the colorectum. The natural history of these lesions and their role in the adenoma-carcinoma sequence are unknown. We studied ACF in a subset of patients randomized to placebo (n = 17), celecoxib (200 mg twice daily; n = 15), or celecoxib (400 mg twice daily; n = 13) in the Adenoma Prevention with Celecoxib (APC) trial. Magnification chromoendoscopy was done to identify, count, and biopsy ACF within the rectum at baseline and after 8 to 12 months of treatment. A total of 655 ACF were identified in 45 patients. We examined 70 of these ACF histologically, and all 70 were nondysplastic. Cohort characteristics and APC trial treatment results for substudy patients were similar to those of the overall APC trial. There was no significant modulation of ACF by celecoxib (versus placebo; P = 0.77). Immunohistochemical comparison of ACF with adjacent normal mucosa showed that ACF had an increased proliferative index as determined by Ki-67 (P < 0.0001), but lacked other features of neoplasia such as increased cyclooxygenase-2 expression and microvessel density, nuclear localization of beta-catenin, or decreased expression of the tumor suppressors SMAD4, Estrogen Receptor alpha, or MGMT. Only baseline SMAD4 expression in ACF correlated with posttreatment adenoma recurrence (independent of treatment arm; P = 0.01). The presence or number of nondysplastic ACF did not correlate with a higher risk of synchronous advanced or recurrent adenomas. Our overall results indicated that nondysplastic ACF were not accurate surrogate endpoint biomarkers of recurrent colorectal adenomas in the APC trial.

Chemoprevention of colorectal cancer with cyclooxygenase-2 inhibitors: two steps forward, one step back.

Chronic inflammation is a tissue-specific process implicated in several diseases of an aging population, including cancer, cardiovascular disease, and arthritis. Cyclooxygenase-2 (COX-2) is a mediator of acute and chronic inflammation, and drugs designed to specifically target this enzyme have achieved widespread clinical use. Unfortunately, randomised trials of selective COX-2 inhibitors for cancer prevention have shown that beneficial effects in one type of tissue can be accompanied by toxic effects in another. These trials documented a significant reduction in adenoma formation in patients at high risk for colorectal cancer, with reductions in advanced disease occurrence from 28-66% over 3 years. As a result, these studies provided important evidence for the involvement of COX-2 in early colorectal tumorigenesis. In the same patients, however, these placebo-controlled clinical trials revealed a little-understood relation between COX-2 and maintenance of cardiovascular integrity. During the 3 years of treatment, patients who received selective COX-2 inhibitors were 1.3-3.4-times more likely to have serious cardiovascular events than those treated with placebo. This article will discuss the biological rationale for using selective COX-2 inhibitors in cancer chemoprevention, and outline new avenues of research into toxic effects and tissue specificity that are necessary to allow their successful use in patients at risk for colorectal cancer.