Abstract PO2-18-01: Assessment of Initial Dosing and Dose Management of Sacituzumab Govitecan-hziy (SG) and How Dosing Practices Impact Duration of Therapy (DOT)
Authors: Gorantla Vikram , Alwon Erin , Gart Mike , Li John , Blanc Simon , Brenneman Dawn , Varughese Prateesh , Scott Justin , Katzen Harvey 
Published: May 2024

Background: As the Phase 3 ASCENT trial’s safety analysis found that a 10m/kg dose of SG resulted in better efficacy than treatment with a lower dose, this examination sought to use real-world data to evaluate how patients (pts) were dosed compared to the recommended starting dose for SG as well as how the starting dose impacted pt DOT.1 In addition, this assessment sought to understand the rate of dose reductions for pts treated with SG and how the use of dose reductions impacted DOT.

Methods: This assessment utilized the Integra Connect PrecisionQ real-world de-identified database of over 2 million cancer pts across 500 sites of care to evaluate starting dose and rate of dose reduction, as well as whether starting dose and use of dose reductions impacted DOT for pts treated with SG. In analyzing the DOT, pts were required to have had a follow-up of 12 months or greater. The SG pt data utilized reflects treatments through May 31, 2023. Comparisons of proportions were conducted using a two sample two-tailed z-test and compared median DOT using a Wilcoxon Rank Sum test. Descriptive analyses were used to summarize pt demographic statistics.

Results: 433 pts treated with SG were identified with an average age at treatment start of 59.6 (median of 61); 17% identified as Black or African American and 62% identified as White or Caucasian. Of the 433 pts treated with SG, 83% received the recommended starting dose of 10mg/kg, 13% initiated treatment at 7.5mg/kg and the remaining 5% received 5mg/kg or less. Among the 433 pts, 37% had a dose reduction. The rate of dose reductions for those who started at 10 mg/kg was 35% compared to 43% for pts who started at 7.5mg or less (p &gt;0.05). The rate of dose reductions for those who started on 7.5mg/kg were 39% (N = 57) compared to 55% (N = 18) for those who started on 5mg/kg or less (p &gt;0.05). The median DOT among the pts regardless of starting dose was 116 days (N = 336). The median DOT for pts who started on 10mg/kg was 136 days (N = 254) compared to 77 (N =61) for pts who started on 7.5 mg/kg or less (p = .012). The median DOT for pts who started on 7.5mg/kg was 91 days (N = 166) compared to 58 (N = 17) for those who started on 5mg/kg or less. The median DOT for pts who had a dose reduction was 172 days (N = 125) compared to 89 days (N = 190) for those who did not have a dose reduction (p &lt; 0.001).

Conclusion: The assessment found that SG-treated pts who received the recommended starting dose had a longer DOT than those who received a lower starting dose. In addition, dose reductions on SG contributed to a longer time on therapy for pts. These findings suggest using the recommended starting dose for SG and then dose managing via reductions to help keep pts on therapy and delay disease progression. Further evaluation of the impact of starting dose would be needed to understand pt differences in prior lines of therapy and hormonal status to understand how those factors impact DOT.

[1] Rugo, H.S., Tolaney, S.M., Loirat, D. et al. Safety analyses from the phase 3 ASCENT trial of sacituzumab govitecan in metastatic triple-negative breast cancer. npj Breast Cancer 8, 98 (2022). https://doi.org/10.1038/s41523-022-00467-1

Citation Format: Vikram Gorantla, Erin Alwon, Mike Gart, John Li, Simon Blanc, Dawn Brenneman, Prateesh Varughese, Justin Scott, Harvey Katzen. Assessment of Initial Dosing and Dose Management of Sacituzumab Govitecan-hziy (SG) and How Dosing Practices Impact Duration of Therapy (DOT) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-18-01.