Molecular tumor boards (MTBs) are multidisciplinary groups that combine molecular and clinical data from cancer patients in order to formulate treatment recommendations for precision medicine. To date, there is insufficient data to support the use of singleplex or next-generation sequencing (NGS) technologies to select first-line therapy for patients with metastatic breast cancer (MBC), but considering the high number of level II alterations, according to the ESMO scale for clinical actionability of molecular targets (ESCAT), it is suggested to include patients in molecular screening programs in order to be able to offer targeted therapies for specific genomic alterations. This article aims at reviewing the most recent literature related to the most used methodologies/approaches for molecular diagnostics and variants’ classification, summarizing the internationally published molecular screening studies in support of MTB activity and, in the end, discussing MTBs’ current position and role in Italy, the number of which is increasing, also thanks to the thrust of institutions.

Background/Objectives: HER2-positive breast cancer (HER2⁺BC) is an aggressive subtype, with neoadjuvant treatment (NAT) aiming to achieve a pathological complete response (pCR) to improve long-term outcomes. Trastuzumab emtansine (T-DM1) has been established as the standard of care in the adjuvant setting for HER2⁺BC patients who do not obtain pCR. The ATD study aimed to evaluate the real-world tolerability of T-DM1 in this setting. The secondary objective was to assess the effectiveness. Methods: This was a multicenter, retrospective study across 24 Italian oncology centers, including 410 patients with HER2⁺BC treated with adjuvant T-DM1 following a lack of pCR after NAT. Patient characteristics, NAT regimens, and surgical outcomes were recorded. Tolerability was assessed by documenting adverse events (AEs) according to the CTCAE (v5.0). Preliminary effectiveness was evaluated in terms of relapse-free survival (RFS) and overall survival (OS). Results: Overall, 228 patients (55.6%) experienced at least one AE related to T-DM1, with 4.9% experiencing grade 3 or higher AEs. The most common AEs were hepatotoxicity (18.5%) and thrombocytopenia (17.6%). T-DM1 was discontinued in 10.0% of patients due to toxicity. After a median follow-up of 25 months, 31 relapse events (7.6%) and 22 deaths (5.4%) were reported. The preliminary incidence of RFS and OS events was similar between patients who completed the T-DM1 course and those who discontinued it early. Conclusions: T-DM1 demonstrated a manageable safety profile, and the adverse events were consistent with those reported in randomized trials. The data are not yet sufficient to allow for a formal analysis of RFS and OS, and long-term follow-up is required.

Hereditary breast and ovarian cancer (HBOC) syndrome is responsible for approximately 10% of breast cancers (BCs). The HBOC gene panel includes both high-risk genes, i.e., a four times higher risk of BC (BRCA1, BRCA2, PALB2, CDH1, PTEN, STK11 and TP53), and moderate-risk genes, i.e., a two to four times higher risk of BC (BARD1, CHEK2, RAD51C, RAD51D and ATM). Pathogenic germline variants (PGVs) in HBOC genes confer an absolute risk of BC that changes according to the gene considered. We illustrate and compare different BC risk estimation models, also describing their limitations. These models allow us to identify women eligible for genetic testing and possibly to offer surgical strategies for primary prevention, i.e., risk-reducing mastectomies and salpingo-oophorectomies.

Pertuzumab and trastuzumab have been shown to improve the outcomes of patients with metastatic breast cancer, with a rate of left ventricular dysfunction of approximately 6%. We report the case of a postmenopausal woman who presented with Takotsubo syndrome during maintenance therapy with pertuzumab and trastuzumab, in association with fulvestrant (an anti-estrogen) and denosumab. After normalization of cardiac function, therapy with pertuzumab and trastuzumab was resumed in the absence of new cardiac toxicity. We report the first clinical case of Takotsubo syndrome during double anti-HER2 blockade in association with an antiestrogen. Furthermore, we show how anti-HER2 therapy can be safely resumed after the detection of Takotsubo syndrome.

Background: Neoadjuvant chemotherapy plus dual HER2 blockade is standard for HER2-positive early breast cancer (EBC), but the impact of hormone receptor (HR) status and PIK3CA mutations with anthracycline-free regimens remains unclear. Methods: We retrospectively analyzed 56 patients with stage II–III HER2-positive EBC treated with neoadjuvant pertuzumab–trastuzumab–taxane (THP) at a single institution. Pathological complete response (pCR, ypT0/is ypN0) was the primary endpoint; secondary endpoints were safety and early disease-free/overall survival (DFS/OS), while associations of HR status and PIK3CA mutations with pCR were explored. Results: The overall pCR rate was 60.7%, in line with major dual-HER2 neoadjuvant trials. HR-negative patients achieved higher pCR rates than HR-positive patients (85.7% vs. 45.7%; p = 0.007; odds ratio 7.125), identifying HR status as the main clinical factor associated with response. Among 36 patients with PIK3CA testing, pCR rates appeared similar in mutated and wild-type tumors (62.5% vs. 60.7%), but the small number of mutated cases precludes firm conclusions. At a median follow-up of 42 months, only five DFS and one OS event had occurred, so survival analyses are exploratory and should be interpreted cautiously. THP demonstrated an excellent safety profile, with minimal grade 3–4 toxicity, and no clinically relevant hematological, cardiac, or pulmonary events. Conclusions: Anthracycline-free THP is a highly active, well-tolerated neoadjuvant option for HER2-positive EBC, with particularly high pCR rates in HR-negative disease. HR status emerged as a key determinant of pCR, whereas the role of PIK3CA mutations remains inconclusive and requires confirmation in larger prospective studies.