Cancer Clinical Trials: Basics Explained (Phases & More)

04/15/2021 By Dr. Dan Platt

There are many guides floating around the Internet on how to go about finding clinical trials for cancer patients. However – they are not always the most practical. Most everyone recommends initial conversations with your doctor or care team to see if they have any suggestions about a study or can help you search for a specific trial. Having an initial conversation with your care team is never the wrong place to start, but it is essential to acknowledge that most doctors and nurses do not have the time to keep themselves up-to-date with information about thousands of ongoing cancer trials.

Unless you are being treated at a major cancer center, your oncologist is less likely than you might think to know about active trials at their institution. Some institutions are better at communicating trial opportunities than others, and some doctors are more proactive in reaching out to colleagues about patients who may qualify. Since you are the best advocate for your health, it is worth learning and researching trials yourself. That way, when you bring the information you’ve found to your care team, you will know which questions to ask and be able to direct your doctor to look at a few specific trials that you think are best for you.

Understand the Basics of a Cancer Clinical Trial

You will have to know a few things before you start your search. The first is that clinical trials are conducted in phases. The trial phase tells you quite a bit of information about what is currently understood about the study drug, including its safety and effectiveness.

Phases of a Clinic Trial: Explained

Let’s talk about each phase of a cancer clinical trial in ways you can understand.

Phase 1: Determine dosing + check safety

  • First in humans. Drugs in this phase are being tested for the first time in people and therefore come with a much more significant risk!
  • Small size. These trials typically enroll 10-50 patients and are offered at very few hospitals (usually only one major cancer center).
  • Not specific. Often includes patients with many different types of cancer because doctors do not know against which cancer the drug will be most effective.

Key Point: Phase 1 trials are the most experimental and carry the most risk. They may be worth thinking about if (1) there are no other treatment options for your disease, or (2) you want to try a cutting-edge therapy that will not be approved for at least five years.

Example: Chimeric antigen receptor T-cell therapy (CAR-T) for breast cancer

Phase 2: Understand effectiveness

  • Medium size. These trials typically enroll 50-100 patients and are offered at hospitals and cancer centers around the country (usually 5 to 10 locations).
  • Specific. Drugs are tested at a particular dose and in a specific patient group (e.g. breast cancer patients with estrogen receptor positive disease).
  • Cost vs. Benefit Analysis. Phase 2 trials represent a critical decision point for doctors, drug companies, and patients. They answer questions like:
    • Does the positive impact for patients outweigh the negative impact of side effects?
    • Is this drug effective enough to test in larger, more expensive trials?
    • What is the best way to use the drug (by itself or in combination, in early-stage patients or later-stage, etc.)?

Key Point: Phase 1 & Phase 2 are often combined in cancer trials to speed up the drug development process and make the best treatments available sooner. Phase 2 trials frequently test drugs that are known to work in some capacity against human cancers. Consider a Phase 2 trial if: (1) You do not qualify for any Phase 3 trials and/or (2) You want to help doctors maximize the effectiveness of a promising treatment.

Example: Cancer vaccines in combination with chemo + targeted therapy

Phase 3: Compare to standard treatment

  • Usually randomized and blinded. This means that patients are picked randomly to receive either the study drug or the standard treatment. Phase 3 trials are often double-blinded, meaning neither the patient nor the doctor knows which treatment the patient is receiving.

This is where a placebo comes in handy! A placebo allows the trial to stay blinded and prevents bias that might compromise the results. For instance, if a trial is being done to understand whether adding the study drug to a typical chemo regimen will improve patient outcomes, the trial must compare one group that receives Drug X + chemo to a second group that receives chemo plus a placebo. If a placebo wasn’t used, then patients who received only chemo would know which group they were in! It is important to note that, in cancer trials, the patient will seldom receive just a placebo.

  • Large size. These trials typically enroll 100-1000 patients, depending on the rarity of the disease, and are offered at many hospitals, cancer centers, and clinics worldwide.
  • More complex. Phase 3 trials are longer than other trials and collect more data because the results will decide if the FDA should approve the drug.

Key Point: Phase 3 trials are usually the best ones to enroll in, period. Typically, the risks and potential benefits of a study drug are somewhat understood at this point, so these trials are more likely to succeed and achieve the desired result. Also, these trials are easier to get into because they enroll more people and tend to be more convenient for patients because they are offered in more locations (usually all the major hospitals in every state).

This video from the Mayo Clinic provides a helpful overview of clinical trials:

 The Clinical Trial Journey

Deskside with Dr. Dan

“One small way I am personally contributing to education is through sharing my take on academic and industry articles, using my medical background to boil down the jargon and pull out the benefits of the news for you.”

– Dan Platt, M.D.

Chief Medical Officer

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