Study on Using Isosorbide Mononitrate or Diltiazem to Reduce Blood Vessel Damage in Gastrointestinal Cancer Patients Receiving Fluoropyrimidine Therapy

Inclusion Criteria

• Age 18 or older.
• Diagnosed with gastrointestinal cancer (such as colon, rectal, gastric, or esophageal cancer) and scheduled to receive fluoropyrimidine therapy (5-FU or capecitabine).
• Planning to start 5-FU or capecitabine treatment, either alone or with other therapies.
• In good general health with an ECOG performance status of 0, 1, or 2.
• Able to visit Mayo Clinic for tests and follow-up appointments.
• Willing to provide written consent to participate.
• Have a systolic blood pressure of at least 120 mmHg and a resting heart rate of at least 70 beats per minute.
• Completed all initial assessments and showed a significant change in blood vessel reactivity.
• Able to tolerate and willing to take study medications (isosorbide mononitrate, diltiazem, or placebo).
• Agree to start study medication 5 days before and continue through the fluoropyrimidine treatment cycle.
• Provide written consent for the randomization phase.

Exclusion Criteria

• Currently using or planning to use long-acting nitrates or calcium channel blockers.
• Allergic to or unable to take nitrates or calcium channel blockers.
• Low blood pressure (systolic blood pressure less than 120 mmHg) or low heart rate (less than 70 beats per minute).
• Recent heart attack or severe heart failure requiring treatment.
• Recent severe heart issues or heart surgery.
• Heart block without a pacemaker.
• Use of medications like Viagra within 48 hours of joining the study.
• Uncontrolled health issues like unstable angina, irregular heartbeats, infections, or mental health conditions that affect study participation.
• Physical limitations that prevent certain tests.
• Pregnant or breastfeeding.
• Participating in another clinical trial that might interfere with this study.