My Treatment Approach: Metastatic Triple-Negative Breast Cancer - Episode 3
Comprehensive discussion on the safety and efficacy profile of the antibody-drug conjugate (ADC) sacituzumab govitecan and managing ADC-related adverse events in patients with mTNBC.
Sara A. Hurvitz, MD:You mentioned that the sacituzumab is a TROP2-targeting antibody drug conjugate with this TOPO1 payload. I'm interested in hearing what your experiences are in terms of patient tolerability to this. What type of adverse effects have you seen your patients experience? How is their quality of life on this therapy?
Gregory Vidal, MD, PhD: I at first expected diarrhea to be higher. Diarrhea is an adverse effect that is common, but I don't see as much diarrhea as I once anticipated. Nausea is 1 of the highest and more common adverse effects we see, but that's easily managed with antinausea medicine. The adverse effects that we have more issue with managing is really neutropenia and how do you manage neutropenia from the use of G-CSF [granulocyte colony stimulating factor? Where do you use it? How do you use it? When do you dose reduce? Those are the more common adverse effects, nausea, diarrhea, and neutropenia with this drug. But overall compared with standard of care chemotherapy, the drug is very well tolerated. We also noticed some alopecia in all patients on this drug.
Sara A. Hurvitz, MD:Yes, I agree with you completely. The alopecia patients must be warned about because it's complete. I've not seen a patient keep any hair on their heads, so, it's important to warn them. I have seen patients struggle with diarrhea, so, I think it's really important to equip them with antimotility agents at home and make sure that they're in good contact with us. I think as oncologists, we're pretty good at managing diarrhea, but certainly, patients need to be educated about this and prepared. In terms of the neutropenia, I think most of my patients going on this therapy have come off of several lines of cytotoxic chemotherapy either in the adjuvant setting or metastatic setting. Therefore, their bone marrow's a little bit beat up, and I have found that the majority of my patients benefit from growth factors, as you mentioned. I'm using a couple of days of G-CSF between days 1 and 8, and then on day 9 I'm using a long-acting G-CSF to help support patients and keep their dose as high as possible to help with the efficacy. There is an interesting poster that was presented at ASCO 2022—I'm not sure if you saw it—looking at the effective drug levels and the benefits of maximizing our ability to treat. Lots of supportive factors might help us to avoid dose reductions, and that may dove tail into better outcomes. What do you think?
Gregory Vidal, MD, PhD: I certainly agree. My issue over here, and having practiced in the San Francisco Bay Area, Ihadn't had as much pushback as I do in the Memphis area from the insurance company pushing back on coverage of those supported medications. So that's been a little bit of an issue here. When we first created our care plan for this drug, G-CSF was placed into those patients prophylactically, and we have to take it back because most of those [treatments] were being denied. Eventually, most of my patients end up getting on it anyway, but you are correct. This is exactly what I do. Two to three days of short acting in between day 1 and day 8 and then I give a long acting at day 8 because there's a 2-weeks break overall. So I think our management is very similar and spot on for this drug.
Sara A. Hurvitz, MD:Yes, I agree completely, and I just want to underscore something you said earlier, which is that I do think the quality of life is quite good on this agent. I think we're beginning to see patient-reported outcome data to indicate that quality of life is preserved in these patients and their time till deterioration does appear to be prolonged—which is good for patients dealing with metastatic disease, which is incurable. I think the ability to achieve disease control also helps with quality of life from an emotional standpoint, but often also from a symptom standpoint.
Transcript edited for clarity.