The Value of Drug Testing Before Treatment Selection

UpToDate is the source of cancer drug recommendations most oncologists use in the United States. It conforms to the NCCN guidelines but provides additional information about the NCCN drugs and strategies for using those drugs. UpToDate provides the Objective Response Rate (ORR) for each drug, the percentage of patients who showed at least a partial response to the drug in a clinical trial. For most late-stage cancer patients, the average ORRs of the drugs in UpToDate are around 20%. Given this low response rate, drug testing that guides oncologists to the treatments most likely to work enormously benefits patients.

Short-Term Benefit

If a drug test with 80% positive predictive accuracy (PPA) tests multiple drugs that have a 20% Objective Response Rate (ORR) and identifies one or more drugs that show response to the test, then the likelihood of the patient responding to their next therapy increases from 20% to 80%. This dramatic increase is enormously valuable for late-stage patients, who may have limited time to try multiple different drugs.

Another way of quantifying the benefit is to calculate the number of drugs required to achieve an 80% likelihood of response. If drug testing with 80% PPA identifies a drug that shows a response, then the number of drugs required to achieve an 80% likelihood of response is one. Without a drug test, the expected number of 20% effective treatments required to achieve an 80% likelihood of response is seven. To achieve an 80% likelihood of response, the drug test reduces the expected number of drugs that would have to be tried in the patient from seven to one, a considerable difference for late-stage patients. Note that if the PPA of the drug test is 50%, the expected number of 20% effective treatments required to achieve a 50% likelihood of response is three. Even a 50% PPA test (which sounds relatively poor) has a substantial patient benefit.

Long-Term Benefit

Relapsing on treatment indicates something about the cancer has changed. Rather than trying the next drug identified by the original drug test, it may be more effective to rerun the test. The drug that just failed in the patient should no longer be identified as a drug that causes a response, and the new set of drugs that show response should reflect the new characteristics of the recurrent cancer. Our hope is that repeating this strategy at each relapse will, at least for some patients, reduce their cancer to a chronic disease that can be managed by changing treatments under the repeated guidance of the drug test.

Eventually each patient will run out of UpToDate treatments. For most patients, there are additional FDA-approved drugs for their cancer, but without drug testing, it may be difficult to justify trying these additional drugs. There are three potential sources of drugs beyond the late-stage drugs in UpToDate:

  1. Drugs in UpToDate recommended for earlier-stage patients,

  2. Drugs in the NCCN guidelines for this cancer but not included in UpToDate, and

  3. FDA-approved drugs not included in the NCCN guidelines for this cancer (off-label drugs)

With drug testing and an oncologist willing to try new options, drugs from these three additional sources that show response in a drug test could be made available to late-stage patients after they have failed the late-stage drugs in UpToDate.

Travera can help

If you want to consider Ex-Vivo Cancer Drug Testing to evaluate a broad range of FDA-approved drug options and assess their potential for treating your unique cancer, Travera’s team can offer support and guidance.

Travera offers email and phone support (781-874-0808) to address any questions about the Rapid Therapy Guidance test and testing process. Our goal is to bring you hope and an improved outcome. Don't hesitate to contact us anytime; we will respond within 24 hours.