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Although metastatic breast cancer (MBC) is treatable, it is not curable and most patients remain on treatment indefinitely. While oncologists commonly prescribe the recommended starting dose (RSD) from the FDA-approved label, patient tolerance may differ from that seen in clinical trials. We report on a survey of medical oncologists' perspectives about treatment-related toxicity and willingness to discuss flexible dosing with patients.We disseminated a confidential survey via social media/email in Spring 2021. Eligible respondents needed to be US-based medical oncologists with experience treating patients with MBC.Of 131 responses, 119 were eligible. Physicians estimated that 47% of their patients reported distressing treatment-related side effects; of these, 15% visited the Emergency Room/hospital and 37% missed treatment. 74% (n = 87) of doctors reported improvement of patient symptoms after dose reduction. 87% (n = 104) indicated that they had ever, if appropriate, initiated treatment at lower doses. Most (85%, n = 101) respondents did not believe that the RSD is always more effective than a lower dose and 97% (n = 115) were willing to discuss individualized dosing with patients.Treatment-related side effects are prevalent among patients with MBC, resulting in missed treatments and acute care visits. To help patients tolerate treatment, oncologists may decrease initial and/or subsequent doses. The majority of oncologists reject the premise that a higher dose is always superior and are willing to discuss individualized dosing with patients. Given potential improvements regarding quality of life and clinical care, dose modifications should be part of routine shared decision-making between patients and oncologists.

Background: MBC is generally incurable and most patients will remain on treatment indefinitely. Medical oncologists commonly prescribe the Recommended Starting Dose (RSD) from the FDA-approved label based upon clinical trial results, with lower doses typically administered after patients’ experience treatment-related toxicity. However, patient tolerance for the RSD in the real-world setting differs from that of clinical trial participants. We previously reported results from a survey of patients with MBC that revealed patients’ willingness to discuss individualized dosing with medical oncologists (Loeser, ASCO 2021). We now report results from a corresponding survey of medical oncologists. Methods: Patient advocates and medical oncologists from the Patient-Centered Dosing Initiative disseminated a confidential, 28-question online survey to US medical oncologists via professional organizations, social media, and email lists. The survey’s objectives were to understand oncologists’ perspectives regarding the prevalence and severity of treatment-related toxicity, increase recognition of the impact of dosage-related mitigation strategies on clinical outcomes, and determine oncologists’ willingness to discuss flexible dosing approaches when patients with MBC begin a new systemic treatment or experience side effects. Results: 131 medical oncologists responded to the survey within the allotted period (4/26 -5/24, 2021). 12 were excluded from further analysis because they were not US-based medical oncologists or lacked experience treating patients with MBC. Of the 119 eligible participants, 85% specialized in breast cancer, 66% worked in an academic setting, and 82% had practiced for > 5 years. Overall, physicians estimated that 47% of patients reported a distressing treatment-related side effect, 15% visited the ER/hospital, and 37% required a break from treatment. The most common mitigation strategies (96% each) were prescribing supportive medication, offering suggestions for palliation, and lowering the dose. Dose reduction was effective, with 74% of doctors reporting patient improvement thereafter. 87% (n=104) of physicians indicated that they had started patients at a lower dose for various reasons, and 60% noted that these patients felt better than patients commencing the same therapy on the RSD. The drugs/classes most commonly prescribed at lower initial doses were capecitabine (91%), taxanes (60%), and palbociclib (50%). Notably, the majority (85%, n=101) of oncologists surveyed do not believe that the RSD is always more effective than a lower dose, and 97% (n=115) would be willing to discuss drug dosing options with patients based on their unique personal attributes. Conclusion: Medical oncologists reported that a high percentage of patients experience distressing toxicity, a need for acute care, and dose interruptions with standard delivery of therapy for MBC. Many elect to decrease the starting dose for select drugs, and almost all are open to discussing lower initial and successive doses. We conclude that these patient-centered dosing discussions should be part of routine care and may consequently improve QOL for patients with MBC. Citation Format: Anne L Loeser, Aditya Bardia, Mark E. Burkard, Kevin M Kalinsky, Jeffrey Peppercorn, Hope S. Rugo, Martha Carlson, Janice Cowden, Julia Maues, Sheila McGlown, Maryam Lustberg. Patient-centered dosing: Oncologists’ perspectives about treatment-related side effects and individualized dosing for patients with metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-10-09.

Sacituzumab Govitecan (also known by the brand name TRODELVY®) is a new and available treatment for metastatic triple-negative breast cancer, or mTNBC for short. Metastatic breast cancer means the breast cancer has spread to other parts of the body. Triple negative means the breast cancer does not have 3 common proteins on the cell surface called receptors. This is a summary of the ASCENT study, published in the New England Journal of Medicine in April 2021. This study compared Sacituzumab Govitecan with standard chemotherapy. Chemotherapy is a treatment that kills cancer cells or stops them from dividing. 529 people with mTNBC took part in the study across 7 countries. All who took part had already received 2 previous chemotherapies, which stopped working for their cancer. The study showed that patients who took Sacituzumab Govitecan lived longer than those who took a different chemotherapy while on the study. Tumors shrank in more patients who took Sacituzumab Govitecan than in patients who took chemotherapy. In general, patients who took Sacituzumab Govitecan experienced more side effects. This included low levels of a type of white blood cell known as neutrophils (neutropenia) and loose or watery stool (diarrhea). Use of supportive care lessened these side effects. This summary also includes insights and perspectives from 2 breast cancer patient advocates. ClinicalTrials.gov NCT number: NCT02574455 . To read the full Plain Language Summary of this article, click on the View Article button above and download the PDF. Link to original article here .