How to treat lobular cancer in the adjuvant setting?

Neoadjuvant therapy in hormone Receptor-Positive/HER2-Negative breast cancer

Neoadjuvant therapy is commonly used in patients with locally advanced or inoperable breast cancer (BC). Neoadjuvant chemotherapy (NACT) represents an established treatment modality able to downstage tumours, facilitate breast-conserving surgery, yet also achieve considerable pathologic complete response (pCR) rates in HER2-positive and triple-negative BC. For patients with HR+/HER2- BC, the choice between NACT and neoadjuvant endocrine therapy (NET) is still based on clinical and pathological features and not guided by biomarkers of defined clinical utility, differently from the adjuvant setting where gene-expression signatures have been widely adopted to drive decision-making. In this review, we summarize the evidence supporting the choice of NACT vs NET in HR+/HER2- BC, discussing the issues surrounding clinical trial design and proper selection of patients for every treatment. It is time to question the binary paradigm of responder vs non-responders as well as the "one size fits all" approach in luminal BC, supporting the utilization of continuous endpoints and the adoption of tissue and plasma-based biomarkers at multiple timepoints. This will eventually unleash the full potential of neoadjuvant therapy which is to modulate patient treatment based on treatment sensitivity and surgical outcomes. We also reviewed the current landscape of neoadjuvant studies for HR+/HER2- BC, focusing on antibody-drug conjugates (ADCs) and immunotherapy combinations. Finally, we proposed a roadmap for future neoadjuvant approaches in HR+/HER2- BC, which should be based on a staggered biomarker-driven treatment selection aiming at impacting long-term relevant endpoints.

Evolution of biological features of invasive lobular breast cancer: comparison between primary tumor and metastases

BACKGROUND

Invasive lobular carcinoma (ILC) has unique clinical-biological features. Phenotypical differences between primary tumours (PTs) and metastases (M) have been described for invasive ductal carcinoma, but data on ILC are limited.

METHODS

We retrospectively analysed patients with recurrent ILC from our institution from 2013 to 2020. We evaluated the discordance of the oestrogen receptor (ER), progesterone receptor (PgR) and HER2 between PT and M, to understand prognostic and therapeutic implications.

RESULTS

Thirteen percent (n = 91) of all patients had ILC. We observed 15%, 44% and 5% of ER, PgR and HER2 status discordance between PT and M. ER/PgR discordance was related to receptor loss and HER2 mainly due to gain. PT presented a luminal-like phenotype (93%); 6% and 1% were triple-negative (TNBC) and HER2-positive. In M, there was an increase in TNBC (16%) and HER2-positive (5%). Metastasis-free survival and overall survival (OS) were different according to clinical phenotype, with poorer prognosis for HER2+ and TNBC (p < 0.001); OS after metastatic progression did not differ across phenotypes (p = 0.079). In luminal-like ILC (n = 85) at diagnosis, we found that OS after relapse was poorer in patients experiencing a phenotype switch to TNBC but improved in patients with HER2 gain (p = 0.0028). Poorer survival was reported in patients with a PgR and/or ER expression loss of ≥25%. There was HER2-low enrichment in M1 (from 37% to 58%): this change was not associated with OS (p > 0.05).

CONCLUSION

Our results suggest that phenotype switch after metastatic progression may be associated with patients' outcomes. Tumour biopsy in recurrent ILC could drive treatment decision-making, with prognostic implications.

ROSALINE: a phase II, neoadjuvant study targeting ROS1 in combination with endocrine therapy in invasive lobular carcinoma of the breast

Invasive lobular carcinoma (ILC) is the most common histologic subtype of breast cancer after invasive ductal carcinoma (i.e., no special type [NST]). ILC differs from NST in clinical presentation, site-specific metastases and response to conventional therapies. Loss of E-cadherin protein expression, due to alterations in its encoding gene CDH1, is the most frequent oncogenic event in ILC. Synthetic lethality approaches have shown promising antitumor effects of ROS1 inhibitors in models of E-cadherin-defective breast cancer in in vivo studies and provide the rationale for testing their clinical activity in patients with ILC. Entrectinib is a tyrosine kinase inhibitor targeting TRK, ROS1 and ALK tyrosine kinases. Here, the authors present ROSALINE (NCT04551495), a phase II study testing neoadjuvant entrectinib and endocrine therapy in women with estrogen receptor-positive, HER2-negative early ILC.

Benefit of adjuvant chemotherapy in patients with special histology subtypes of triple-negative breast cancer: a systematic review

PURPOSE

Breast cancer (BC) is a leading cause of morbidity, disability, and mortality in women, worldwide; triple-negative BC (TNBC) is a subtype traditionally associated with poorer prognosis. TNBC special histology subtypes present distinct clinical and molecular features and sensitivity to antineoplastic treatments. However, no consensus has been defined on the best adjuvant therapy. The aim of the review is to study the evidence from literature to inform the choice of adjuvant treatments in this setting.

METHODS

We systematically searched literature assessing the benefit of adjuvant chemotherapy in patients with TNBC special histotypes (PROSPERO: CRD42020153818).

RESULTS

We screened 6404 records (15 included). All the studies estimated the benefit of different chemotherapy regimens, in retrospective cohorts (median size: 69 patients (range min-max: 17-5142); median follow-up: 51 months (range: 21-268); mostly in Europe and USA). In patients with early-stage adenoid cystic TNBC, a marginal role of chemotherapy was reported. Similar for apocrine TNBC. Medullary tumors exhibited an intrinsic good prognosis with a limited role of chemotherapy, suggested to be modulated by the presence of tumor-infiltrating lymphocytes. A significant impact of chemotherapy on the overall survival was estimated in patients with metaplastic TNBC. Limitations were related to the retrospective design of all the studies and heterogeneous treatments received by the patients.

CONCLUSIONS

There is potential opportunity to consider treatment de-escalation and less intense therapies in some patients with early, special histology-type TNBC. International efforts are indispensable to validate prospective clinical decision models.

Benefit of adjuvant chemotherapy in patients with lobular breast cancer: A systematic review of the literature and metanalysis

The role of adjuvant chemotherapy (aCT) for patients with localized lobular breast cancer (ILC) is still controversial. It is unclear what is the magnitude of benefit of the CT in this setting. In this systematic review of the literature and metanalysis, we aimed to estimate the benefit of aCT in addition to the standard treatments in the early ILC setting. We identified the records by searching Medline, CENTRAL, Web of Science, SCOPUS, and Google Scholar, and the meeting proceeding of the principal oncology meetings of the last 10 years, with no language or time restriction. A research strategy was developed with mapped and MeSH terms. Studies on the clinical use of aCT reporting survival outcomes in the ILC setting were double-screened and tabulated. PRISMA methodology was used for data extraction and synthesis. We extracted information on the study design and setting, eligible population and population size, histology variants, menopausal status, treatment regimens, follow-up duration. Hazard ratios (HR) and 95% confidence interval (CI) were extracted and transformed into logHR and corresponding standard error to obtain the Summary HR (SHR). Heterogeneity (I² statistics) and publication bias (Macaskill test) were tested; a random effect models provided by SAS Proc Mixed was used for data analysis. Sensitivity analysis was conducted to examine the impact of inclusion criteria on the summary results. Disease-free (DFS), overall (OS) and cancer-specific survival (BCSS) were the primary endpoints of the investigation. The systematic review and metanalysis included 38,387 patients across 8 clinical studies. aCT was not associated with an improvement of OS (SHR 0.99; 95%CI 0.86-1.14), with low heterogeneity (I² = 28%) and no publication bias (p = 0.43). Sensitivity analysis resulted in unchanged conclusions. We did not perform a metanalysis of the DFS estimates, as only reported in 3 studies. The value of aCT in improving DFS was unconfirmed, consistently with the OS results. Our research did not confirm a certain role of aCT for patients with ILC. Research gaps were identified, warranting the development of prospective, controlled ad hoc investigations.