Patients with cancer (PC) are at high risk of acquiring COVID-19 and can develop more serious complications. Deeper understanding of vaccines immunogenicity in this population is crucial for adequately planning vaccines programs. The ONCOVac study aimed to comprehensively assess the immunogenicity of mRNA-1273 vaccine in terms of humoral and cellular response. We conducted a prospective, single-center study including patients with solid tumours treated with cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i), immunotherapy (IT) or chemotherapy (CT). Patients were enrolled previously to vaccination with mRNA-1273. We also involved health care workers (HCW) to serve as a control group. We took blood samples before first dose administration (BL), after first dose (1D), and after second dose (2D). The primary objective was to compare the rate and magnitude of T cell response after second dose whereas safety and humoral response were defined as secondary objectives. We also collected patient reported outcomes after both the first and second vaccine dose and a six-month follow-up period to diagnose incident COVID-19 cases was planned. The rate of specific anti-S serologic positivity (anti-S IgG cut-off point at 7,14 BAU/mL) was significantly higher in HCW compared to PC after 1D (100% versus 83.8%; p = 0.04), but similar after 2D (100% versus 95.8%; p = 0.5). This difference after 1D was driven by PC treated with CT (100% versus 64.5%; p = 0.001). Cellular response after 2D was significantly lower in PC than in HCW for both CD4+ (91.7% versus 59.7%; p = 0.001) and CD8+ (94.4% versus 55.6%; p < 0.001) T cells. We found a difference on pre-existing CD4+ T cell response in HCW comparing to PC (36% and 17%, p = 0.03); without difference in pre-existing CD8+ T cell response (31% and 23%, p = 0.5). After excluding patients with pre-existing T cell response, PC achieved even lower CD4+ (50.9% versus 95.5%, p < 0.001) and CD8+ (45.5% versus 95.5%, p < 0.001) T cell response compared with HCW. Regarding safety, PC reported notably more adverse events than HCW (96.6% versus 69.2%, p < 0.001). We demonstrated that PC showed a similar humoral response but a lower T cell response following two doses of mRNA-1273 vaccination. Further studies are needed to complement our results and determine the implication of low T cell response on clinical protection of PC against COVID-19.

Although metastatic breast cancer remains an incurable disease, there are patients with a limited number of metastatic lesions that, in addition to systemic therapy, can be treated with “radical therapy” and sometimes reach the status of no long-term evidence of disease. Whether or not these patients can be considered cured is still a matter of debate. Unfortunately, the definition of the oligometastatic disease remains unclear, and it can occur with multiple different presentations. The absence of remarkable biomarkers, the difficulty in designing the appropriate clinical trials, and the failure to offer this group of patients radical approaches in advanced-stage clinical trials are just some of the current problems that we face in treating patients with oligometastatic breast cancer. Although most of the data come from retrospective studies and do not use the same definition of “oligometastatic disease,” here we review the main studies exploring the role of surgery or radiotherapy in patients with the oligometastatic disease and the different results. Some, but not all, studies have shown an increase in survival when surgery and/or radiotherapy were performed for oligometastatic disease. However, better clinical trial designs are needed to confirm the role of “aggressive” approaches for patients with breast cancer and oligometastatic disease.

Determining whether an ipsilateral breast carcinoma recurrence is a true recurrence or a new primary remains challenging based solely on clinicopathologic features. Algorithms based on these features have estimated that up to 68% of recurrences might be new primaries. However, few studies have analyzed the clonal relationship between primary and secondary carcinomas to establish the true nature of recurrences. This study analyzed 70 breast carcinomas from 33 patients using immunohistochemistry, FISH, and massive parallel sequencing. We compared 35 primary carcinomas with the associated recurrences, identifying 24 (68.6%) as true recurrences, 7 (20%) as new primaries, and 4 (11%) as undetermined. Twenty-eight primary carcinomas were invasive carcinomas (22 of no special type, 5 invasive lobular, and 1 invasive micropapillary carcinoma), and 7 were in situ (6 ductal and 1 lobular). Time to recurrence was longer for new primaries (median 12.8 y) than for true recurrences (median 6.8 y). Among the new primary cases, 6 of 7 (85%) patients had undergone mastectomy as their initial treatment. Clinicopathologic classifications of invasive carcinomas overestimated the number of new primaries (41.6% to 68.6%), partially due to phenotype conversion in 14% of true recurrences. Although 41.7% of recurrences showed private mutations or amplifications relevant to tumor progression, such as PIK3CA, PIK3R1, MAP3K1, AKT1, GATA3, CCND1, MDM4, or T P 5 3; a common mutational progression pattern was not identified. Further studies, including larger series, are necessary to evaluate the prognostic significance of the molecular classification of recurrences.

The clinical implications of specific pathogenic and likely pathogenic variant (LP/PV) types and locations in the BRCA1 orBRCA2 tumor-suppressor genes remain to be elucidated. The BRCA BCY Collaboration (NCT03673306) is an international, multicenter, hospital-based, retrospective cohort study that included BRCA carriers diagnosed with invasive breast cancer at the age of ≤40 years between January 2000 and December 2020. In this analysis, only patients with detailed available information on LP/PVs in the BRCA genes were included. Clinicopathological features and survival outcomes [disease-free survival (DFS) and overall survival (OS)] were investigated according to LP/PV type [insertion-deletion (indel) versus single-nucleotide variants versus copy number variations; truncating versus non-truncating LP/PVs; frameshift versus nonsense versus splicing versus missense LP/PVs] and location (exon involved and protein domain). Out of 5660 patients from 109 centers worldwide, 3294 were eligible for the present analysis (2080 BRCA1 and 1214 BRCA2). The distribution of LP/PV types showed no meaningful associations with baseline clinicopathological features. BRCA1 protein-truncating variants were associated with worse OS compared with non-truncating variants [hazard ratio (HR) 2.00, 95% confidence interval (CI) 1.17-3.41]. A similar, though non-significant, trend was observed for BRCA2. Missense variants were linked to better OS for both BRCA1 (HR 0.48, 95% CI 0.28-0.84) and BRCA2 carriers (HR 0.17, CI 0.03-0.96). Regarding variant location, BRCA1 LP/PVs outside exons 2, 10, and 19 were associated with improved OS. In BRCA2, LP/PVs located in exons 15-26 and other regions were linked to worse DFS compared with those in exon 10, with no significant differences in OS. This study advances our understanding of the influence of specific types of BRCA LP/PVs on breast cancer characteristics and outcomes. A deeper understanding of these variant-specific features will drive future research and support the development of tailored clinical strategies based on individual BRCA variant.

Although breast cancer has led the way toward precision medicine, more research is still needed to increase curation rates in patients with early disease and to prolong survival with an optimal quality of life in the metastatic setting. Last year, big advances were achieved toward these goals thanks to the significant impact of immunotherapy on survival in triple‐negative breast cancer and the exciting results of antibody‐drug conjugates.Plain Language Summary: The development of new drugs and biomarkers to select those patients who will benefit of them are crucial in improving survival in breast cancer. Last year, the emergence of antibody‐drug conjugates and the reaffirmation of the potential of immunotherapy in breast cancer were the most important findings.

Few data are available about the immune response to mRNA SARS-CoV-2 vaccines in patients with breast cancer receiving cyclin-dependent kinase 4/6 inhibitors (CDK4/6i). We conducted a prospective, single-center study of patients with breast cancer treated with CDK4/6i who received mRNA-1273 vaccination, as well as a comparative group of healthcare workers. The primary endpoint was to compare the rate and magnitude of humoral and T-cell response after full vaccination. A better neutralizing antibody and anti-S IgG level was observed after vaccination in the subgroup of women receiving CDK4/6i, but a trend toward a reduced CD4 and CD8 T-cell response in the CDK4/6i group was not statistically significant. There were no differences in the rate of COVID-19 after vaccination (19% vs. 12%), but breakthrough infections were observed in those with lower levels of anti-S IgG and neutralizing antibodies after the first dose. A lower rate of CD4 T-cell response was also found in those individuals with breakthrough infections, although a non-significant and similar level of CD8 T-cell response was also observed, regardless of breakthrough infections. The rate of adverse events was higher in patients treated with CDK4/6i, without serious adverse events. In conclusion, there was a robust humoral response, but a blunted T-cell response to mRNA vaccine in women receiving CDK4/6i, suggesting a reduced trend of the adaptative immune response.