Trastuzumab is a humanized mAb directed against the extracellular domain of the tyrosine kinase receptor HER2. Trastuzumab has shown clinical activity in HER2-overexpressing breast cancers and, at present, is currently approved for patients whose tumours have this abnormality, in both the metastatic and the adjuvant setting. Several issues about its optimal use, however, are still unresolved. One of the reasons for these uncertainties lies in the absence of conclusive data about its mechanism of action and possible primary or acquired resistance mechanisms. Therefore, clinical questions such as how to optimize patient selection, how to prevent resistance to trastuzumab, or what is the optimal management of those patients whose tumours progress during treatment still await convincing answers. This review summarises the current knowledge on the preclinical and clinical evidence about the mechanism of action of trastuzumab and on the mechanisms underlying the development of resistance and also briefly discusses their possible clinical implications.

Epithelial ovarian cancer (EOC) is the leading cause of death among gynecological malignancies. Despite surgery and chemotherapy, 5-years survival rates have improved only modestly over the past few decades remaining at 45% for advanced stages. Therefore, novel therapies are urgently needed. The presence of tumor-infiltrating lymphocytes (TILs) in OC tumor microenvironment (TME) has already proved to be correlated with overall survival (OS), while immune evasion mechanisms are associated with poor prognosis. Although these data indicate that immunotherapy has a strong rationale in OC, single agent immune-checkpoints inhibitors (ICIs) have shown only modest results in this malignancy. In this review, we will discuss immune-targeting combination therapies and adoptive cell therapy (ACT), highlighting the challenges represented by these strategies, which aim at disrupting the stroma-tumor barrier to boost immune system against ovarian cancer.

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PARPis are valuable options in patients with recurrent ovarian cancer with promising activity in different stages of this disease. Further studies are required to better define optimal clinical settings, predictors of response beyond BRCA mutations and strategies to overcome secondary resistance of PARPis therapy in EOC.