Key Details Not to Ignore in ADC Drug Treatment

Previously, Dr. Li introduced various treatment methods and outcomes for patients with HER2 mutation non-small cell lung cancer to Sister Zhao’s family, including traditional chemotherapy, chemotherapy + immunotherapy, and anti-angiogenic + chemotherapy. At the same time, the doctor briefly introduced the new anti-cancer drug, antibody-drug conjugate (ADC), particularly the impressive efficacy of Trastuzumab Deruxtecan in clinical trials. This introduction filled Sister Zhao’s family with confidence about the future.

Today, we will delve into the precautions for using ADC drugs and further understand how to manage HER2-ADC treatment.

After presenting the research data on the ADC drug, seeing Sister Zhao’s family gain more confidence in fighting the disease, Dr. Li continued to explain the usage of Trastuzumab Deruxtecan: “Unlike traditional oral small molecule targeted drugs, HER2-ADC drugs are primarily administered via intravenous injection, allowing the drug components to quickly reach the tumor site through the bloodstream. Before starting treatment, we will calculate the required drug dosage based on each patient’s weight to ensure that each patient receives a suitable treatment dose, maximizing efficacy.”

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Sister Zhao’s son asked, “So how much dosage would my mom need?”

What is the dosage?

“I just mentioned that the latest data released at the World Lung Cancer Conference shows that Trastuzumab Deruxtecan has the best balance between safety and efficacy at a dosage of 5.4mg/kg, which is also the recommended dosage for lung cancer patients in the instructions. Using this data for calculations, if Sister Zhao weighs 55 kilograms, then the calculated dosage would be 55kg * 5.4mg/kg = 297mg, so the dosage for one treatment should be 297mg.”

Seeing that Sister Zhao’s family seemed to have no concept of this value, Dr. Li added: “One bottle of Trastuzumab Deruxtecan is 100mg, so for Sister Zhao’s case, the required dosage for one treatment is 3 bottles.”

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“Do we need to use so much at once?” Sister Zhao asked in surprise.

“Yes, this is necessary to ensure safety while ensuring the dosage is sufficient to maximize anti-tumor efficacy!” Dr. Li replied.

Sister Zhao’s husband asked, “If we use three bottles at once, does that mean the infusion time will be long?”

How long is each infusion?

“The infusion time for the first treatment will be a bit longer, generally requiring no less than 90 minutes, to observe and assess Sister Zhao’s tolerance to the drug. If the tolerance is good after the first treatment, the infusion time for subsequent treatments will be correspondingly reduced, with each infusion lasting no less than 30 minutes,” Dr. Li explained.

“So how often will my mom be treated?”

How long is the treatment cycle?

Dr. Li said, “This is what I will talk to you about next. Currently, for Trastuzumab Deruxtecan, the plan is to administer it once every three weeks, meaning every 21 days, to ensure that the drug maintains a stable concentration in the body and provides continuous therapeutic effects.”

“How long will I need to be treated?” Sister Zhao continued to ask.

Dr. Li replied, “The duration of treatment depends on various factors, including Sister Zhao’s disease progression, drug tolerance, and treatment efficacy. Generally, we will regularly assess based on the tumor’s response to the drug and the patient’s tolerance. If Trastuzumab Deruxtecan can effectively control the tumor and you can tolerate the treatment, it will continue until the disease progresses or adverse reactions become intolerable.”

At this moment, Sister Zhao’s son asked again: “What if, due to special circumstances, I can’t bring my mom back to the hospital for treatment on the 21st day, will it affect the treatment’s efficacy?”

What if there is a delay or missed dose?

Dr. Li replied: “Indeed, ideally, we hope to follow the planned treatment schedule every 21 days. However, we also understand that sometimes special circumstances may prevent timely treatment. If Sister Zhao misses the scheduled treatment date, for example, if there is a one-week delay, she needs to come to the hospital for treatment as soon as possible, rather than waiting for the next cycle.”

Sister Zhao’s son then asked: “If we miss this treatment and come back after a week, will the next injection be based on the original 21-day schedule or will it start from the day of the missed treatment?”

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Dr. Li replied: “If this treatment is delayed for a week, we will recalculate the next treatment time starting from this delayed treatment date. In other words, starting from the date of the actual treatment, the next treatment will occur in three weeks, ensuring a three-week interval between doses. The purpose of this is to ensure consistency in treatment intervals while ensuring that side effects do not accumulate and affect the quality of life.”

“Mom, we must stick to the treatment schedule,” Sister Zhao’s son said, patting Sister Zhao’s shoulder.

“Okay.” Sister Zhao nodded.

“So, are there any special precautions during treatment?” Sister Zhao asked.

“Yes, there are a few points to note,” Dr. Li continued.

“Firstly, after starting Trastuzumab Deruxtecan, it cannot be mixed with other ADC drugs, nor can other ADC drugs be used as substitutes. For example, if Sister Zhao has a strong reaction after this injection and consults another doctor for a change in medication, this is absolutely inadvisable, as each ADC drug has different targets, drug structures, and expected therapeutic effects, and they cannot be arbitrarily substituted. Arbitrary combination or substitution may lead to unimaginable consequences such as excessive drug toxicity or impaired efficacy!”

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“Okay, Dr. Li, we understand. You can rest assured.” Seeing Dr. Li express this matter very seriously, Sister Zhao and her family did not dare to be careless in their response.

“Secondly, during the infusion, it is necessary to confirm whether the patient has any infusion-related reactions.”

“What are infusion-related reactions?” Sister Zhao’s son asked.

“Infusion-related reactions (IRR) refer to a series of adverse reactions or side effects that occur during intravenous drug infusion,” Dr. Li explained. “These reactions may be caused by the drug itself or may be due to rapid infusion rates or other related factors.”

Sister Zhao’s son then asked: “What specific adverse reactions might occur?”

Dr. Li said: “They can manifest in various forms, such as fever, chills, nausea, vomiting, headache[1]. Although the incidence of infusion-related reactions is not high, about 2.3% (including hypersensitivity reactions and infusion-related reactions), we still need to closely monitor the patient’s reactions, especially in the initial stages of treatment. If any signs of adverse reactions are observed, we will immediately take measures, such as adjusting the infusion rate or, if necessary, pausing or stopping treatment to ensure the patient’s safety.”

“So family members must observe whether the patient exhibits any discomfort symptoms during the infusion and promptly inform the medical staff for handling.”

“Okay, Dr. Li, we understand.” Sister Zhao replied.

At this time, Sister Zhao’s son asked again: “Dr. Li, I have another question. You mentioned earlier that these reactions occur during intravenous infusion. What about other adverse reactions caused by the drug itself? Since ADC drugs are a combination of targeted and chemotherapy drugs, does that mean the corresponding adverse reactions might also be more numerous?”

What specific side effects does Trastuzumab Deruxtecan have? How to cope with them? Stay tuned for the next issue: “How to Deal with the Side Effects of ADC Drugs? Here’s the Doctor’s Recommendation.”

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