[Concomitant radiotherapy and trastuzumab: Rational and clinical implications]

Survival analysis of palliative radiotherapy in patients with HER-2+ metastatic breast cancer

Background

Whether radiotherapy can improve the long-term survival of HER-2+ metastatic breast cancer remains unclear. We launched this study to explore the effect of HER-2+ metastatic breast cancer patients through anti-HER-2 targeted therapy + radiotherapy.

Methods

488 HER-2 + metastatic breast cancer patients who received anti-HER2 targeted ± local radiotherapy from March 2006 to September 2021 were retrospectively collected. Patients were divided into a radiotherapy group (n=207) and a non-radiotherapy group (n=281) based on whether they received radiotherapy or not. 1: 1 propensity matching analysis was used to determine two groups of patients with similar baselines.

Results

Before matching, the radiotherapy group (n=207) had a median overall survival (mOS) of 51.7 months (48.8-63.8), which was superior to the non-radiotherapy group's (n=281) mOS of 33.9 months (27.9-39.9) (P < 0.0001). Moreover, the radiotherapy group exhibited better 1-year (94.6% vs 83.9%), 3-year (70.8% vs 45.5%), and 5-year (43.3% vs 25.0%) survival rates compared to the control group. Propensity score matching analysis identified 135 pairs of baseline-matched patients. In the matched groups, the mOS was 57.2 (44.5-69.8) months in the radiotherapy group (n=135) and 34.1 (27.5-40.6) months in the non-radiotherapy group (n=135), showing a statistically significant difference (P < 0.0001). Additionally, the radiotherapy group demonstrated 1-, 3-, and 5-year survival rates of 93.2%, 71.5%, and 46.9%, respectively, while those in the non-radiotherapy group were 89.4%, 45.8%, and 22.2%, respectively. Multivariate Cox analysis revealed that the presence of brain metastasis, liver metastasis, and radiotherapy were identified as independent predictive factors significantly associated with OS.

Conclusion

In patients with HER-2 positive metastatic breast cancer, radiotherapy was associated with better survival benefits compared to those who did not receive radiotherapy.

Systemic investigation of inetetamab in combination with small molecules to treat HER2-overexpressing breast and gastric cancers

Most patients with metastatic breast cancer or gastric cancer who are treated with trastuzumab, an anti-HER2 monoclonal antibody, become refractory to the drug within a year after the initiation of treatment. Although the combination of trastuzumab with pertuzumab produced synergetic effects in the treatment of HER2-overexpressing cancers, not all patients with HER2 overexpression benefited from the trastuzumab plus pertuzumab combination. To improve the clinical benefits of trastuzumab, we systemically investigated the combination of inetetamab (Cipterbin), an analog of trastuzumab, with a variety of small molecules, including tyrosine kinase inhibitors (TKIs) and chemotherapeutic agents in vivo. We showed that pan-TKIs-induced synergistic antitumor effects with inetetamab in the treatment of these two types of cancers and that adding chemotherapeutic agents to the existing TKI plus anti-HER2 monoclonal antibody combination strategies induced additional inhibitory effects, suggesting that such combination strategies may be choices for the treatment of these two tumors. Thus, combination therapies targeting distinct and broad pathways that are essential for tumor growth and survival can be effective for treating metastatic breast cancers and gastric cancers.