Commentary: New treatments and trial results, October 2023

Earlier this year, the US Food and Drug Administration approved the antibody-drug conjugate sacituzumab govitecan for patients with unresectable locally advanced or metastatic hormone receptor (HR)–positive, human epidermal growth factor receptor 2 (HER2)–negative breast cancer (BC) who have received endocrine-based therapy and at least two additional systemic therapies in the metastatic setting. This was based on data from the phase 3 TROPiCS-02 study, which included 543 patients with pretreated, endocrine-resistant HR+/HER2− metastatic BC (MBC) who were randomly assigned to receive either sacituzumab govitecan or a single-agent chemotherapy of the physician's choice. The study previously showed that sacituzumab govitecan demonstrated significant progression-free survival benefit over chemotherapy in this patient population.

A recently published study by Rugo and colleagues presented the final analysis of overall survival and endpoints by trophoblast cell surface antigen 2 (Trop-2) expression. Results showed that at the 12.5-month median follow-up, sacituzumab govitecan vs chemotherapy improved overall survival by 3.2 months (hazard ratio 0.79; P = .020). The survival benefit was consistent across different levels of Trop-2 expression. No new adverse events were reported; however, one fatal adverse event (septic shock caused by neutropenic colitis) was determined to be related to sacituzumab govitecan treatment. These updated data continue to support the use of sacituzumab govitecan as a new treatment option for patients with endocrine-resistant HR+ and HER2- MBC.

It remains unclear whether anti-HER2 therapy alone (without chemotherapy) is an effective treatment approach for patients with ERBB2-positive MBC in the first-line setting. Huober and the Swiss Group for Clinical Cancer Research, the Unicancer Breast Group, and the Dutch Breast Cancer Research Group report a phase 2 trial that included 210 patients with ERBB2+ MBC who were randomly assigned to receive pertuzumab plus trastuzumab with or without chemotherapy followed by trastuzumab-emtansine as the second-line therapy in both groups. Despite worse progression-free survival in the nonchemotherapy vs the chemotherapy group (8.4 months [95% CI 7.9-12.0] vs 23.3 months [95% CI 18.9-33.1]), overall survival rates were comparable at 2 years of follow-up (79.0% [90% CI 71.4%-85.4%] vs 78.1% [90% CI 70.4%-84.5%]). Furthermore, adverse events were more frequent in the chemotherapy cohort, with small quality-of-life improvements from baseline in the nonchemotherapy cohort. Further prospective data are needed to confirm whether a chemotherapy-free approach is an acceptable treatment approach in certain population of patients, without unfavorable effects on overall survival.

Prior results from the SOFT and TEXT trials have shown improved survival with the addition of ovarian function suppression (OFS) in premenopausal women after chemotherapy. The ASTRRA trial is a similar phase 3 study that included 1282 premenopausal women with estrogen receptor–positive BC who remained premenopausal or regained ovarian function after chemotherapy and were randomly assigned to receive tamoxifen with or without OFS. The results showed a consistent disease-free survival benefit in women who received tamoxifen plus OFS vs tamoxifen alone (85.4% vs 80.2%; hazard ratio 0.67; P = .003) after a median follow-up of 8 years. There were no significant differences in 8-year OS rates between the two groups (P = .305), although both cohorts had high OS rates overall (> 95%). This trial highlights the overall excellent prognosis in this patient population and underscores the importance of OFS in the subgroup of patients who remain in a premenopausal state or resume ovarian function after chemotherapy.

The ICE study (Ibandronate with or without Capecitabine in Elderly patients with early breast cancer) was a phase 3 trial looking at 1358 patients age ≥ 65 years with node-positive or high-risk node-negative early BC who were randomly assigned to receive 2 years of ibandronate with or without capecitabine for six cycles in the adjuvant setting. At a median follow-up of 61 months, the 5-year invasive disease-free survival rates were similar amongst patients treated with adjuvant ibandronate plus capecitabine and ibandronate alone (hazard ratio 0.96; 95% CI 0.78-1.19). Outcomes were independent of age, nodal status, and hormone receptor status. The incidences of high-grade gastrointestinal disorders (6.7% vs 1.0%; P < .001) and skin toxicity (14.6% vs 0.6%; P < .01) were significantly higher in the capecitabine plus ibandronate arm vs the ibandronate alone arm.

Adjuvant capecitabine plus ibandronate failed to show improved survival outcomes compared with ibandronate alone in older patients with node-positive/high-risk node-negative BC. This was similar to results of the CALGB 49907 trial, which showed inferior survival for adjuvant capecitabine compared with standard adjuvant chemotherapy in patients ≥ 65 years of age.¹ Therefore, although oral capecitabine may be more tolerable than intravenous polychemotherapy in older patients with high-risk BC, this should be weighed against lower efficacy.

Additional Reference

1. Muss HB, Berry DA, Cirrincione CT, et al, for the CALGB Investigators. Adjuvant chemotherapy in older women with early-stage breast cancer. N Engl J Med. 2009;360:2055-2065. doi: 10.1056/NEJMoa0810266

Earlier this year, the US Food and Drug Administration approved the antibody-drug conjugate sacituzumab govitecan for patients with unresectable locally advanced or metastatic hormone receptor (HR)–positive, human epidermal growth factor receptor 2 (HER2)–negative breast cancer (BC) who have received endocrine-based therapy and at least two additional systemic therapies in the metastatic setting. This was based on data from the phase 3 TROPiCS-02 study, which included 543 patients with pretreated, endocrine-resistant HR+/HER2− metastatic BC (MBC) who were randomly assigned to receive either sacituzumab govitecan or a single-agent chemotherapy of the physician's choice. The study previously showed that sacituzumab govitecan demonstrated significant progression-free survival benefit over chemotherapy in this patient population.

A recently published study by Rugo and colleagues presented the final analysis of overall survival and endpoints by trophoblast cell surface antigen 2 (Trop-2) expression. Results showed that at the 12.5-month median follow-up, sacituzumab govitecan vs chemotherapy improved overall survival by 3.2 months (hazard ratio 0.79; P = .020). The survival benefit was consistent across different levels of Trop-2 expression. No new adverse events were reported; however, one fatal adverse event (septic shock caused by neutropenic colitis) was determined to be related to sacituzumab govitecan treatment. These updated data continue to support the use of sacituzumab govitecan as a new treatment option for patients with endocrine-resistant HR+ and HER2- MBC.

It remains unclear whether anti-HER2 therapy alone (without chemotherapy) is an effective treatment approach for patients with ERBB2-positive MBC in the first-line setting. Huober and the Swiss Group for Clinical Cancer Research, the Unicancer Breast Group, and the Dutch Breast Cancer Research Group report a phase 2 trial that included 210 patients with ERBB2+ MBC who were randomly assigned to receive pertuzumab plus trastuzumab with or without chemotherapy followed by trastuzumab-emtansine as the second-line therapy in both groups. Despite worse progression-free survival in the nonchemotherapy vs the chemotherapy group (8.4 months [95% CI 7.9-12.0] vs 23.3 months [95% CI 18.9-33.1]), overall survival rates were comparable at 2 years of follow-up (79.0% [90% CI 71.4%-85.4%] vs 78.1% [90% CI 70.4%-84.5%]). Furthermore, adverse events were more frequent in the chemotherapy cohort, with small quality-of-life improvements from baseline in the nonchemotherapy cohort. Further prospective data are needed to confirm whether a chemotherapy-free approach is an acceptable treatment approach in certain population of patients, without unfavorable effects on overall survival.

Prior results from the SOFT and TEXT trials have shown improved survival with the addition of ovarian function suppression (OFS) in premenopausal women after chemotherapy. The ASTRRA trial is a similar phase 3 study that included 1282 premenopausal women with estrogen receptor–positive BC who remained premenopausal or regained ovarian function after chemotherapy and were randomly assigned to receive tamoxifen with or without OFS. The results showed a consistent disease-free survival benefit in women who received tamoxifen plus OFS vs tamoxifen alone (85.4% vs 80.2%; hazard ratio 0.67; P = .003) after a median follow-up of 8 years. There were no significant differences in 8-year OS rates between the two groups (P = .305), although both cohorts had high OS rates overall (> 95%). This trial highlights the overall excellent prognosis in this patient population and underscores the importance of OFS in the subgroup of patients who remain in a premenopausal state or resume ovarian function after chemotherapy.

The ICE study (Ibandronate with or without Capecitabine in Elderly patients with early breast cancer) was a phase 3 trial looking at 1358 patients age ≥ 65 years with node-positive or high-risk node-negative early BC who were randomly assigned to receive 2 years of ibandronate with or without capecitabine for six cycles in the adjuvant setting. At a median follow-up of 61 months, the 5-year invasive disease-free survival rates were similar amongst patients treated with adjuvant ibandronate plus capecitabine and ibandronate alone (hazard ratio 0.96; 95% CI 0.78-1.19). Outcomes were independent of age, nodal status, and hormone receptor status. The incidences of high-grade gastrointestinal disorders (6.7% vs 1.0%; P < .001) and skin toxicity (14.6% vs 0.6%; P < .01) were significantly higher in the capecitabine plus ibandronate arm vs the ibandronate alone arm.

Adjuvant capecitabine plus ibandronate failed to show improved survival outcomes compared with ibandronate alone in older patients with node-positive/high-risk node-negative BC. This was similar to results of the CALGB 49907 trial, which showed inferior survival for adjuvant capecitabine compared with standard adjuvant chemotherapy in patients ≥ 65 years of age.¹ Therefore, although oral capecitabine may be more tolerable than intravenous polychemotherapy in older patients with high-risk BC, this should be weighed against lower efficacy.

Additional Reference

1. Muss HB, Berry DA, Cirrincione CT, et al, for the CALGB Investigators. Adjuvant chemotherapy in older women with early-stage breast cancer. N Engl J Med. 2009;360:2055-2065. doi: 10.1056/NEJMoa0810266

Earlier this year, the US Food and Drug Administration approved the antibody-drug conjugate sacituzumab govitecan for patients with unresectable locally advanced or metastatic hormone receptor (HR)–positive, human epidermal growth factor receptor 2 (HER2)–negative breast cancer (BC) who have received endocrine-based therapy and at least two additional systemic therapies in the metastatic setting. This was based on data from the phase 3 TROPiCS-02 study, which included 543 patients with pretreated, endocrine-resistant HR+/HER2− metastatic BC (MBC) who were randomly assigned to receive either sacituzumab govitecan or a single-agent chemotherapy of the physician's choice. The study previously showed that sacituzumab govitecan demonstrated significant progression-free survival benefit over chemotherapy in this patient population.

A recently published study by Rugo and colleagues presented the final analysis of overall survival and endpoints by trophoblast cell surface antigen 2 (Trop-2) expression. Results showed that at the 12.5-month median follow-up, sacituzumab govitecan vs chemotherapy improved overall survival by 3.2 months (hazard ratio 0.79; P = .020). The survival benefit was consistent across different levels of Trop-2 expression. No new adverse events were reported; however, one fatal adverse event (septic shock caused by neutropenic colitis) was determined to be related to sacituzumab govitecan treatment. These updated data continue to support the use of sacituzumab govitecan as a new treatment option for patients with endocrine-resistant HR+ and HER2- MBC.

It remains unclear whether anti-HER2 therapy alone (without chemotherapy) is an effective treatment approach for patients with ERBB2-positive MBC in the first-line setting. Huober and the Swiss Group for Clinical Cancer Research, the Unicancer Breast Group, and the Dutch Breast Cancer Research Group report a phase 2 trial that included 210 patients with ERBB2+ MBC who were randomly assigned to receive pertuzumab plus trastuzumab with or without chemotherapy followed by trastuzumab-emtansine as the second-line therapy in both groups. Despite worse progression-free survival in the nonchemotherapy vs the chemotherapy group (8.4 months [95% CI 7.9-12.0] vs 23.3 months [95% CI 18.9-33.1]), overall survival rates were comparable at 2 years of follow-up (79.0% [90% CI 71.4%-85.4%] vs 78.1% [90% CI 70.4%-84.5%]). Furthermore, adverse events were more frequent in the chemotherapy cohort, with small quality-of-life improvements from baseline in the nonchemotherapy cohort. Further prospective data are needed to confirm whether a chemotherapy-free approach is an acceptable treatment approach in certain population of patients, without unfavorable effects on overall survival.

Prior results from the SOFT and TEXT trials have shown improved survival with the addition of ovarian function suppression (OFS) in premenopausal women after chemotherapy. The ASTRRA trial is a similar phase 3 study that included 1282 premenopausal women with estrogen receptor–positive BC who remained premenopausal or regained ovarian function after chemotherapy and were randomly assigned to receive tamoxifen with or without OFS. The results showed a consistent disease-free survival benefit in women who received tamoxifen plus OFS vs tamoxifen alone (85.4% vs 80.2%; hazard ratio 0.67; P = .003) after a median follow-up of 8 years. There were no significant differences in 8-year OS rates between the two groups (P = .305), although both cohorts had high OS rates overall (> 95%). This trial highlights the overall excellent prognosis in this patient population and underscores the importance of OFS in the subgroup of patients who remain in a premenopausal state or resume ovarian function after chemotherapy.

The ICE study (Ibandronate with or without Capecitabine in Elderly patients with early breast cancer) was a phase 3 trial looking at 1358 patients age ≥ 65 years with node-positive or high-risk node-negative early BC who were randomly assigned to receive 2 years of ibandronate with or without capecitabine for six cycles in the adjuvant setting. At a median follow-up of 61 months, the 5-year invasive disease-free survival rates were similar amongst patients treated with adjuvant ibandronate plus capecitabine and ibandronate alone (hazard ratio 0.96; 95% CI 0.78-1.19). Outcomes were independent of age, nodal status, and hormone receptor status. The incidences of high-grade gastrointestinal disorders (6.7% vs 1.0%; P < .001) and skin toxicity (14.6% vs 0.6%; P < .01) were significantly higher in the capecitabine plus ibandronate arm vs the ibandronate alone arm.

Adjuvant capecitabine plus ibandronate failed to show improved survival outcomes compared with ibandronate alone in older patients with node-positive/high-risk node-negative BC. This was similar to results of the CALGB 49907 trial, which showed inferior survival for adjuvant capecitabine compared with standard adjuvant chemotherapy in patients ≥ 65 years of age.¹ Therefore, although oral capecitabine may be more tolerable than intravenous polychemotherapy in older patients with high-risk BC, this should be weighed against lower efficacy.

Additional Reference

1. Muss HB, Berry DA, Cirrincione CT, et al, for the CALGB Investigators. Adjuvant chemotherapy in older women with early-stage breast cancer. N Engl J Med. 2009;360:2055-2065. doi: 10.1056/NEJMoa0810266