Monoclonal antibodies (mAbs) are immunotherapeutic agents that harness the body’s immune system to promote tumor destruction. These agents are incredibly effective at inducing powerful antitumor responses and increasing overall patient survival. There are different types of mAbs used in cancer treatment. Naked mAbs have no drug or radioactive material attached to them, and are the most common types of mAbs used in cancer treatment. Examples of naked mAbs include trastuzumab and alemtuzumab. Conjugated mAbs are joined to a radioactive particle or chemotherapy drug. Ibritumomab tiuxetan is an example of a radiolabeled conjugated mAb, whereas brentuximab vedotin and ado-trastuzumab emtansine are examples of chemo-labeled conjugated mAbs. Bispecific mAbs are made up of parts of 2 different mAbs, and blinatumomab is an example.
Rituximab is a chimeric mAb used for the treatment of hematologic malignancies. Rituximab, like other mAbs, is associated with an increased incidence of hypersensitivity reaction (HSR) that can range from mild to life-threatening. The incidence of HSR for patients receiving their first dose of rituximab exceeds 70%, resulting in prolonged infusion time, use of rescue medications, patient and caregiver anxiety, and workflow disruption.
Clinical experience shows that slow titration of mAbs can reduce the incidence and severity of HSR. Given the risk for life-threatening reaction, titration practices should be precise. At Memorial Sloan Kettering Cancer Center, all mAbs are primed with a compatible diluent, resulting in patients receiving diluent rather than mAbs during early titration. Indeed, priming rituximab with a diluent is common practice. A small survey of comprehensive cancer centers (CCCs) found that CCC practice guidelines included priming with diluent.
A small pilot with 55 patients was undertaken at Memorial Sloan Kettering Cancer Center to determine whether priming with rituximab reduced the incidence and severity of HSR. Rituximab lines were primed with active drug and data were collected for 3 months on all patients receiving rituximab. These data were compared with 3 months of retrospective data with 50 patients in whom the rituximab line was primed with a diluent. The incidence and grade of HSR were measured using National Cancer Institute Common Terminology Criteria for Adverse Events.
The study showed a decrease in the incidence of HSR in patients receiving first-dose rituximab at 50-mg/hour titration, from 31.8% (diluent) to 11.8% (rituximab), respectively. The grade of reactions remained unchanged in patients receiving subsequent dose; however, the reduced incidence of HSR was clinically significant for first-dose patients.
Although the results of the study were not statistically significant due to the small sample size, practice guidelines recommend priming all nonhazardous titrated mAbs with active drug. Rituximab priming reduces the risk for HSR, improves patient safety, and improves workflow and efficiency. Based on the clinical significance of this study, a hospital-wide practice change was instituted to prime rituximab with active drug.
A prospective study of priming with mAbs is planned, and will include a larger sample size for further statistical analysis. If a reduction of incidence and severity of HSR is confirmed, there is potential for widespread change in clinical practice.
Laudati C, et al. ONS Abstract 148.