No.
The question boils down to, is this self-employment (an "ongoing trade or business", with a clear intention to earn a profit on an ongoing basis), or is this occasional or "other" income. If this is an ongoing trade or business with a profit motive, you can deduct "ordinary and necessary" business expenses, but you also pay 15% self-employment tax on your net profit, in addition to income tax. If this is occasional, hobby, or "other" income, you don't pay self-employment tax, but you can't deduct your expenses. I suppose some people might make a business of participating in clinical trials for profit, but it would be unusual.
More specifically, expenses related to "other income" are miscellaneous itemized deductions subject to the 2% rule, and this type of deduction was eliminated by the 2017 tax reform law for tax years 2018-2025. Starting in 2026, such expenses might be deductible again, depending on what action Congress takes or doesn't take at the time.
Separately, if you were receiving medical care to prevent, treat, mitigate, or cure a disease, you can deduct your travel expenses as itemized medical expenses on schedule A subject to the 7.5% limit, even if the treatment was experimental. Specifically, you can deduct your actual travel expenses, and up to $50 per night for lodging, if the reason for the travel is to receive medical care. You can't deduct meals unless you had to pay for meals as an inpatient as part of your medical care.
