When the ‘Maximum Tolerable Dose’ of Cancer Treatment Isn’t Tolerable

“The schedule is the schedule.”

Those were the exact words from my oncologist when I tried to start a conversation about my ongoing intravenous treatment for HER2-positive metastatic (stage 4) breast cancer. She was definitely shutting that conversation down before it could get started. She’s not wrong--the schedule is indeed the schedule when it comes to Herceptin (trastuzumab) and its biosimilars. There is no information on “de-escalating” treatment by extending the time between doses. Every three weeks is the schedule and that is – more or less – what I have been doing since January 2015.

That is a lot of cancer treatment.

I have multiple friends and acquaintances who, like me, have been receiving Herceptin for HER2-positive metastatic breast cancer for many years but who, unlike me, have moved to four-week, five-week, or six-week schedules. It’s not just my HER2-positive friends who are looking to individualize their treatments. If you are on social media, you know that many women and men in treatment for breast cancer have to reduce treatment doses to be able to tolerate medication side effects.

Over the past few years, there has been a lot written and presented on putting the patient “at the center” and personalizing cancer care. As a seven-year patient, I definitely support all of this. But practically speaking, putting the patient at the center means some big changes to the way health care is practiced.

Enter patient advocate Anne Loeser and the Patient-Centered Dosing Initiative (PCDI), where she spearheads research with other patient advocates (newly including myself) and an impressive medical advisory board consisting of five medical oncologists.

In 2020, Anne and her team set out with the high-level goal of enabling “patients and their doctors to consider the patient's unique physical, situational and psychological factors in order to identify the patient's optimal approved drug dosage when starting a new treatment.” It’s what they termed “The Right Dose”.

Who doesn’t want to reduce toxicity and maintain clinical effectiveness? In fact, cancer drug development in current clinical trial protocols does not seek to do that. Certainly, oncology drug trials are not designed to reduce patient quality of life, but they do tend to seek what is known as the maximum tolerated dose (MTD). In the real world, the highest dose of a drug, which is often based on the MTD, is what most patients are given when they begin a new drug regimen, regardless of their individual specifics.

Typically, it takes problems with side effects and quality of life for dosage to be reduced. One popular drug for treatment of metastatic breast cancer is so frequently started at the highest dose followed by serial dosing reductions as patients experience unacceptable side effects that I know the dose reduction amounts just by belonging to cancer groups on Facebook.

Instead of starting patients with metastatic breast cancer at the highest dose, the PCDI encourages patients and physicians to discuss the idea of optimal dosing for the patient based on a series of nine patient-centered characteristics. You can see that list here.

Many breast cancer drugs permit lower doses when the patient experiences side effects on the highest dose. The PCDI believes these doses should be part of the patient-doctor conversation. To help, the PCDI website (therightdose.org) includes a table with drug-dose reduction guidelines under the “Resources” heading. This chart and other information on the initiative’s website will enable patients to be better informed for themselves, and also help us feel comfortable advocating for something that can seem out of our control.

The PCDI’s first research project was a patient survey, which had over 1,200 responses from people living with metastatic breast cancer. The survey findings reveal how difficult our lives can be: 86% of respondents had experienced one or more side effect from treatment, 20% of these respondents had visited the emergency room or hospital due to a side effect, and 43% had missed one or more scheduled treatments. Most of the people (98%) taking the survey said they talked to their doctors about the side effects, and 82% said they received help from their doctors in addressing the side effects.

Of the 82% of patients whose doctors helped with addressing side effects, 66% received a dose reduction. Dose reductions aren’t the only way to address treatment side effects and the survey reflected the many ways patients and their care teams seek to improve quality of life, such as medications for palliation, specialist referrals and delaying treatments.

In my case, it’s no secret with my health care team that I have been plagued by a treatment side effect: peripheral neuropathy in my hands and feet (the reason why I asked about increasing time between doses). I was disappointed by my oncologist’s response but wasn’t surprised. Over the years, she has always put me first in my care, but not always in the way I’d put myself first. I would like to see pharmaceutical companies, governmental agencies and researchers come together to make it easy for oncologists, including my own, to say “Yes, let’s talk about a dose reduction,” and have the confidence that neither the length nor quality of my life will be affected.

Using words like patient-centered and individualized care isn’t enough if information about alternative dosing is excluded from the data sought by pharmaceutical companies during clinical trials. This is especially true for people living with advanced cancer, such as metastatic breast cancer, where the goal isn’t a cure but to live as long as possible with the best possible quality of life.

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