Response-guided neoadjuvant sacituzumab govitecan for localized triple-negative breast cancer: results from the NeoSTAR trial.

BACKGROUND: Sacituzumab govitecan (SG), a novel antibody-drug conjugate (ADC) targeting TROP2, is approved for pre-treated metastatic triple-negative breast cancer (mTNBC). We conducted an investigator-initiated clinical trial evaluating neoadjuvant (NA) SG (NCT04230109), and report primary results. PATIENTS AND METHODS: Participants with early-stage TNBC received NA SG for four cycles. The primary objective was to assess pathological complete response (pCR) rate in breast and lymph nodes (ypT0/isN0) to SG. Secondary objectives included overall response rate (ORR), safety, event-free survival (EFS), and predictive biomarkers. A response-guided approach was utilized, and subsequent systemic therapy decisions were at the discretion of the treating physician. RESULTS: From July 2020 to August 2021, 50 participants were enrolled (median age = 48.5 years; 13 clinical stage I disease, 26 stage II, 11 stage III). Forty-nine (98%) completed four cycles of SG. Overall, the pCR rate with SG alone was 30% [n = 15, 95% confidence interval (CI) 18% to 45%]. The ORR per RECIST V1.1 after SG alone was 64% (n = 32/50, 95% CI 77% to 98%). Higher Ki-67 and tumor-infiltrating lymphocytes (TILs) were predictive of pCR to SG (P = 0.007 for Ki-67 and 0.002 for TILs), while baseline TROP2 expression was not (P = 0.440). Common adverse events were nausea (82%), fatigue (76%), alopecia (76%), neutropenia (44%), and rash (48%). With a median follow-up time of 18.9 months (95% CI 16.3-21.9 months), the 2-year EFS for all participants was 95%. Among participants with a pCR with SG (n = 15), the 2-year EFS was 100%. CONCLUSIONS: In the first NA trial with an ADC in localized TNBC, SG demonstrated single-agent efficacy and feasibility of response-guided escalation/de-escalation. Further research on optimal duration of SG as well as NA combination strategies, including immunotherapy, are needed.

Immunological differences between primary and metastatic breast cancer.

Background: Little is known about how the immune microenvironment of breast cancer evolves during disease progression. Patients and methods: We compared tumor infiltrating lymphocyte (TIL) count, programmed death-ligand 1 (PD-L1) protein expression by immunohistochemistry and mRNA levels of 730 immune-related genes using Nanostring technology in primary and metastatic cancer samples. Results: TIL counts and PD-L1 positivity were significantly lower in metastases. Immune cell metagenes corresponding to CD8, T-helper, T-reg, Cytotoxic T, Dendritic and Mastoid cells, and expression of 13 of 29 immuno-oncology therapeutic targets in clinical development including PD1, PD-L1, and CTLA4 were significantly lower in metastases. There was also coordinated down regulation of chemoattractant ligand/receptor pairs (CCL19/CCR7, CXCL9/CXCR3, IL15/IL15R), interferon regulated genes (STAT1, IRF-1,-4,-7, IFI-27,-35), granzyme/granulysin, MHC class I and immune proteasome (PSMB-8,-9,-10) expression in metastases. Immunotherapy response predictive signatures were also lower. The expression of macrophage markers (CD163, CCL2/CCR2, CSF1/CSFR1, CXCR4/CXCL12), protumorigenic toll-like receptor pathway genes (CD14/TLR-1,-2,-4,-5,-6/MyD88), HLA-E, ecto-nuclease CD73/NT5E and inhibitory complement receptors (CD-59,-55,-46) remained high in metastases and represent potential therapeutic targets. Conclusions: Metastatic breast cancers are immunologically more inert than the corresponding primary tumors but some immune-oncology targets and macrophage and angiogenesis signatures show preserved expression and suggest therapeutic combinations for clinical testing.

Recommendations for standardized pathological characterization of residual disease for neoadjuvant clinical trials of breast cancer by the BIG-NABCG collaboration.

Neoadjuvant systemic therapy (NAST) provides the unique opportunity to assess response to treatment after months rather than years of follow-up. However, significant variability exists in methods of pathologic assessment of response to NAST, and thus its interpretation for subsequent clinical decisions. Our international multidisciplinary working group was convened by the Breast International Group-North American Breast Cancer Group (BIG-NABCG) collaboration and tasked to recommend practical methods for standardized evaluation of the post-NAST surgical breast cancer specimen for clinical trials that promote accurate and reliable designation of pathologic complete response (pCR) and meaningful characterization of residual disease. Recommendations include multidisciplinary communication; clinical marking of the tumor site (clips); and radiologic, photographic, or pictorial imaging of the sliced specimen, to map the tissue sections and reconcile macroscopic and microscopic findings. The information required to define pCR (ypT0/is ypN0 or ypT0 yp N0), residual ypT and ypN stage using the current AJCC/UICC system, and the Residual Cancer Burden system were recommended for quantification of residual disease in clinical trials.

Remarkably high frequency of EGFR expression in breast carcinomas with squamous differentiation.

The human epidermal growth factor receptor (EGFR) is reportedly overexpressed in 15-20% of breast carcinomas. EGFR overexpression is associated with reduced survival and is inversely correlated with expression of estrogen receptor (ER). This study assessed EGFR expression in breast carcinomas with squamous differentiation. The immunohistochemical (IHC) expression of EGFR was evaluated in 39 breast carcinomas with squamous differentiation (30 pure squamous, 6 adenosquamous, 3 carcinosarcomas) by use of the pharmDx assay (clone 2-18C9, DakoCytomation). Cases were considered positive if at least 10% of the cells showed 1+ positivity in the squamous component. Squamous differentiation was confirmed with IHC for CK5-6 (clone D5/16B4, DakoCytomation). ER, PR, and HER2 status as well as clinical information regarding treatment and outcome were correlated. As a control, a tissue microarray comprising 280 lymph node positive breast carcinomas was evaluated with the same EGFR assay. The 39 patients ranged in age from 33 to 77 years (mean 52). The tumors measured 1.3-30 cm (mean 4.8). Sentinel or full axillary lymph node dissection was performed in 28 patients. Fourteen patients had positive lymph nodes. At the time of initial diagnosis, 3 patients had distant metastasis. Follow-up was available for 16 patients (mean 45 months). Disease-free survival at 3 years was 70%. Among the 39 tumors 87% (34) were positive for EGFR (p<0.0001). Sixty-nine percent (27 of 39) showed >50% 2+ EGFR staining. EGFR-positive tumor cells (showing squamous morphology) were also found in 1 bone, 1 lung, and 8 of 11 lymph node metastases available for evaluation. All 11 lymph nodes showed squamous differentiation. All but 1 of the EGFR+ tumors examined were ER and PR negative. Six EGFR-positive tumors were HER2 positive. No statistically significant differences in HER2 status, size, lymph node status and disease-free survival were observed between EGFR+ and EGFR- cases, but the number of EGFR-negative tumors was quite small. Nine of 280 (3%) of lymph node-positive invasive carcinomas on the tissue microarray were EGFR+; review of the initial diagnostic slides failed to reveal squamous features in all but 1 of the 9 EGFR+ tumors. Breast carcinomas with squamous differentiation are a distinct subgroup of breast tumors with a very high frequency of EGFR positivity. Breast carcinomas of this type would be ideal candidates for a trial with EGFR inhibitors.

Early detection of cytotoxic events between hepatic natural killer cells and colon carcinoma cells as probed with the atomic force microscope.

The atomic force microscope (AFM) is a powerful tool to investigate surface and submembranous structures of living cells under physiological conditions at high resolution. These properties enabled us to study the interaction between live hepatic natural killer (NK) cells, also called pit cells, and colon carcinoma cells in vitro by AFM. In addition, the staining for filamentous actin and DNA was performed and served as a reference, because actin and nuclear observations at the light microscopic level during the cytotoxic interaction between these two cell types have been presented earlier. In this study, we collected evidence that conjugation of hepatic NK cells with CC531s colon carcinoma cells results in a decreased binding of CC531s cells to the substratum as probed with the AFM in contact mode as early as 10 min after cell contact (n = 11). To avoid the lateral forces and smearing artefacts of contact mode AFM, non-contact imaging was performed on hepatic NK/CC531s cell conjugates, resulting in identical observations (n = 3). In contrast, the first cytotoxic signs, as determined with the nuclear staining dye Hoechst 33342, could be observed 3 h after the start of the co-culture. This study illustrates that the AFM can be used to probe early cytotoxic effects of effector to target cell contact in nearby physiological conditions. Other routine cytotoxicity tests detect the first cytotoxic effects after 1.5-3 h co-incubation at the earliest.