Safety and efficacy of pertuzumab and trastuzumab in patients with HER2-Positive metastatic colorectal cancer: comparison of intravenous and subcutaneous formulations. ​

In the landscape of colorectal cancer, a small but significant group of patients carries a specific biological signature known as HER2 positivity. This feature acts like a distinct key on the surface of their cancer cells, driving the disease to grow and making it resistant to standard treatments that block other pathways. For years, doctors have used a powerful combination of two targeted drugs, trastuzumab and pertuzumab, to lock these keys and stop the cancer. These medicines are typically delivered through an intravenous line, a process that requires patients to sit in a clinic for several hours while the drugs drip slowly into their veins. While this method works, it is time-consuming and can sometimes trigger unwanted reactions from the body's immune system, such as fevers or chills, during the infusion.

Recognizing the burden of long clinic visits, scientists developed a new way to deliver these same drugs: a subcutaneous injection. This method involves injecting the medication under the skin, usually into the thigh, a process that takes only a few minutes. While this approach had already been proven safe and effective for breast cancer, its performance in colorectal cancer remained a question. Researchers at the National Cancer Center Hospital East in Japan set out to answer this by looking back at the records of patients who had received either the traditional intravenous method or the new injection method. They wanted to know if the faster injection worked just as well as the slow drip and if it offered a safer, more comfortable experience for patients living with metastatic colorectal cancer.

The study focused on thirty-six patients who had received the drug combination for their HER2-positive disease. The researchers divided them into two groups based on how they were treated: seventeen received the standard intravenous infusion, while nineteen received the subcutaneous injection. A crucial detail of this real-world comparison was that no patient switched between the two methods during their treatment; they stayed with the approach assigned to them from the start. The team carefully tracked how well the cancer responded, how long the patients remained free of disease progression, and what side effects occurred. They also measured the total time a patient spent in the treatment area, from the moment the doctor ordered the medication to the moment the administration was finished.

The results showed that the new injection method was just as effective as the traditional one. In terms of shrinking tumors or keeping them stable, the two groups performed nearly identically. About one-quarter of the patients in the injection group saw their tumors shrink, a rate that matched the intravenous group. The time it took for the cancer to start growing again was also similar for both groups, suggesting that changing how the drug enters the body does not weaken its ability to fight the disease. The researchers found no difference in the progression-free survival or the ability of the treatment to control the cancer's spread between the two methods.

When it came to safety, the injection method showed a promising advantage. The most notable difference was in the frequency of reactions related to the administration of the drug. Patients receiving the intravenous infusion experienced these reactions, such as fever or chills, in nearly half of the cases. In contrast, the group receiving the subcutaneous injection saw these reactions in only about one-sixth of the patients. While the difference did not reach the strict statistical threshold for certainty, the trend was clear and favored the injection. The side effects that did occur in the injection group were mostly mild and limited to the spot where the needle entered the skin. Importantly, no patient in either group suffered a severe, life-threatening reaction, and all side effects were managed without stopping the treatment.

Perhaps the most tangible benefit for the patients was the dramatic reduction in time spent in the clinic. The average time from the doctor's order to the completion of the drug administration was just under two hours for the injection group. For the intravenous group, that same process took more than three and a half hours. This difference of nearly two hours represents a significant reduction in the daily burden for patients who must travel to the hospital for treatment. The researchers noted that this efficiency could help clinics serve more patients and allow individuals to spend less time away from their families and daily lives.

The study concludes that the subcutaneous injection of these two drugs is a viable and convenient alternative to the traditional intravenous method for treating HER2-positive colorectal cancer. It offers the same level of disease control with a lower likelihood of administration-related reactions and a much shorter time commitment. While the study was limited by its small size and the fact that it looked back at past records rather than testing patients prospectively, the findings provide strong support for the use of the injection method in clinical practice. For patients facing this specific type of cancer, the option to receive life-saving medication in a matter of minutes rather than hours represents a meaningful step forward in the quality of their care.