Future potential targets of antibody-drug conjugates in breast cancer.

Metastatic breast cancer (BC) remains an incurable disease. Besides endocrine and targeted agents, chemotherapy is still a relevant therapeutic option for this disease. Recently, antibody-drug conjugates (ADCs) have shown to overcome the lack of tumor specificity and systemic toxicity typically associated with traditional chemotherapies, thus improving the therapeutic index. To effectively exploit this technological breakthrough, identification of optimal target antigens (Ags) is of utmost importance. To make the ideal target, differential expression of target Ags between healthy and cancer tissues, as well as specific mechanisms of ADC internalization after Ag-antibody interaction are required. Therefore, several in silico strategies to identify and characterize new promising candidate Ags have been developed. If initial in vitro and in vivo positive data are documented, thus providing a biological rationale for further Ag investigation, early phase clinical trials are designed. In BC, these strategies have already led to the development of effective ADCs, namely trastuzumab emtansine (T-DM1), trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG), primarily targeting HER2 and TROP-2. However, promising new Ags are currently under investigation, with encouraging results especially coming from targeting HER3, FRα, Tissue Factor, LIV-1, ROR1-2, and B7-H4. In this review, we describe the landscape of emergent and future potential targets (i.e., other than HER2 and TROP-2) investigated in BC for ADC development. Predominant target expression, function, preclinical rationale, potential clinical implication, as well as preliminary clinical trial results are provided.

Treatment of Capecitabine Corneal Side Effects With Autologous Blood-derived Serum Eye Drops.

BACKGROUND/AIM: To describe the clinical progress and management of ocular side effects in a 35-year-old patient with metastatic breast cancer who underwent oral chemotherapy with capecitabine and lapatinib. MATERIALS AND METHODS: Slit lamp evaluation revealed bilateral perikeratic hyperemia, perilimbal conjunctival edema associated with corneal marginal infiltrates and epithelial and anterior stromal defects in both eyes. Slit lamp examination, in vivo confocal microscopy and anterior-segment optical coherence tomography were highly suggestive for limbal stem cell deficiency. The decision to administer autologous blood- derived serum eye drops was made. RESULTS: Following administration of autologous blood-derived serum eye drops, corneal marginal infiltrates, epithelial and stromal defects significantly regressed in both eyes after only 10 days. Chemotherapy was resumed and serum eye drops were prescribed simultaneously. CONCLUSION: Autologous blood-derived serum eye drops may be an adequate therapeutic choice for bilateral corneal lesions detected as ocular side effects of capecitabine.

PANHER study: a 20-year treatment outcome analysis from a multicentre observational study of HER2-positive advanced breast cancer patients from the real-world setting.

BACKGROUND: The evolution of therapeutic landscape of human epidermal growth factor receptor-2 (HER2)-positive breast cancer (BC) has led to an unprecedented outcome improvement, even if the optimal sequence strategy is still debated. To address this issue and to provide a picture of the advancement of anti-HER2 treatments, we performed a large, multicenter, retrospective study of HER2-positive BC patients. METHODS: The observational PANHER study included 1,328 HER2-positive advanced BC patients treated with HER2 blocking agents since June 2000 throughout July 2020. Endpoints of efficacy were progression-free survival (PFS) and overall survival (OS). RESULTS: Patients who received a first-line pertuzumab-based regimen showed better PFS (p < 0.0001) and OS (p = 0.004) than those receiving other treatments. Median PFS and mOS from second-line starting were 8 and 28 months, without significant differences among various regimens. Pertuzumab-pretreated patients showed a mPFS and a mOS from second-line starting not significantly affected by type of second line, that is, T-DM1 or lapatinib/capecitabine (p = 0.80 and p = 0.45, respectively). Conversely, pertuzumab-naïve patients receiving second-line T-DM1 showed a significantly higher mPFS compared with that of patients treated with lapatinib/capecitabine (p = 0.004). Median OS from metastatic disease diagnosis was higher in patients treated with trastuzumab-based first line followed by second-line T-DM1 in comparison to pertuzumab-based first-line and second-line T-DM1 (p = 0.003), although these data might be partially influenced by more favorable prognostic characteristics of patients in the pre-pertuzumab era. No significant differences emerged when comparing patients treated with 'old' or 'new' drugs (p = 0.43), even though differences in the length of the follow-up between the two cohorts should be taken into account. CONCLUSION: Our results confirmed a relevant impact of first-line pertuzumab-based treatment and showed lower efficacy of second-line T-DM1 in trastuzumab/pertuzumab pretreated, as compared with pertuzumab-naïve patients. Our findings may help delineate a more appropriate therapeutic strategy in HER2-positive metastatic BC. Prospective randomized trials addressing this topic are awaited.