Durvalumab and tremelimumab before surgery in patients with hormone receptor positive, HER2-negative stage II-III breast cancer.

A clinical trial was conducted to assess the feasibility of enrolling patients with Stage II or III hormone receptor positive (HR+)/HER2-negative breast cancer to pre-operative dual PD-L1/CTLA-4 checkpoint inhibition administered prior to neoadjuvant chemotherapy (NACT). Eight eligible patients were treated with upfront durvalumab and tremelimumab for two cycles. Patients then received NACT prior to breast surgery. Seven patients had baseline and interval breast ultrasounds after combination immunotherapy and the responses were mixed: 3/7 patients experienced a ≥30% decrease in tumor volume, 3/7 a ≥30% increase, and 1 patient had stable disease. At the time of breast surgery, 1/8 patients had a pathologic complete response (pCR). The trial was stopped early after 3 of 8 patients experienced immunotherapy-related toxicity or suspected disease progression that prompted discontinuation or a delay in the administration of NACT. Two patients experienced grade 3 immune-related adverse events (1 with colitis, 1 with endocrinopathy). Analysis of the tumor microenvironment after combination immunotherapy did not show a significant change in immune cell subsets from baseline. There was limited benefit for dual checkpoint blockade administered prior to NACT in our study of 8 patients with HR+/HER2-negative breast cancer.

Efficacy of Single-Agent Chemotherapy in Endocrine Therapy-Refractory Metastatic Invasive Lobular Carcinoma.

BACKGROUND: Hormone receptor (HR)-positive, HER2-negative metastatic invasive lobular breast cancer (mILC) is distinct from invasive ductal cancer (IDC) in clinicopathologic and molecular characteristics, impacting its response to systemic therapy. While endocrine therapy (ET) combined with targeted therapies has shown efficacy in ET-sensitive mILC, data on chemotherapy in ET-refractory mILC remain limited. We investigated the efficacy of single-agent capecitabine (CAP) versus taxanes (TAX) in ET-refractory HR+ HER2-negative patients with mILC. MATERIALS AND METHODS: Using data from the MD Anderson prospectively collected breast cancer database, we identified patients with HR+ HER2-negative mILC who received prior ET and first-time chemotherapy in the metastatic setting. We compared outcomes between 173 CAP-treated and 96 TAX-treated patients. RESULTS: CAP-treated patients had significantly better median progression-free survival (PFS) than TAX-treated patients (8.8 vs 5.0 months, HR 0.63, P < .001). Overall survival (OS) did not differ significantly between the groups (42.7 vs 36.6 months for CAP vs TAX, respectively, HR 0.84, P = .241). Multivariate analyses for PFS and OS revealed better outcomes in subjects with fewer metastatic sites and those exposed to more lines of ET. Additionally, Black patients showed worse OS outcomes compared to White patients (HR 2.46; P = .001). CONCLUSION: In ET-refractory HR+ HER2-negative mILC, single-agent CAP demonstrated superior PFS compared to TAX. Our findings highlight the potential benefit of CAP in this patient subset, warranting further investigation through prospective trials.

Bone-Targeted Therapy Regimen and Skeletal-Related Events in Patients Surviving Longer Than 2 Years With Metastatic Breast Cancer and Bone Metastasis.

BACKGROUND: Bone-targeted therapy (BTT) including zoledronic acid (ZA) and denosumab decreases the risk of skeletal-related events (SREs) in patients with metastatic breast cancer (MBC) and bone metastasis. The impacts from prolonged BTT on SREs and BTT-associated harms are unknown and are becoming important to understand as these patients survive for longer periods. METHODS AND MATERIALS: We conducted a retrospective study of 224 patients with MBC and bone metastasis who survived for more than 2 years after diagnosis and received treatment at our institution between 2016 and 2021. We defined 3 BTT patterns: (1) ZA only, (2) denosumab only, (3) both ZA and denosumab. The association between these BTT patterns and SREs and harms was assessed using Fisher exact test and logistic regression. RESULTS: Rates of SREs overall were 21.2% of patients given ZA only, 8.8% of those given denosumab only, and 20% of those given both, without statistically significant differences (p = .32). However, those treated with denosumab only had significantly fewer compression fractures (0.7%) (p = .02). BTT-associated harm was observed in 5.8% of the ZA-only group, 11.7% of the denosumab-only group, and 14.3% of the group given both, without statistically significant differences (p = .37). CONCLUSION: Oncologists may have increased flexibility regarding the frequency of administration of BTT along with their choice of agent. Our study showed no significant difference in the prevention of overall SRE or development of BTT-associated harms between the BTT regimens evaluated.

Absence of lobular carcinoma in situ is a poor prognostic marker in invasive lobular carcinoma.

AIM: To determine if the outcomes of patients with ILC co-occurring with LCIS are similar to pure ILC and if the presence of LCIS is a prognostic factor for ILC. METHODS: In an observational, population-based investigation using data from the MD Anderson breast cancer prospectively collected electronic database, we analysed patients with a diagnosis of stage I-III ILC. Patients were divided into two groups: those with ILC with co-occurring ipsilateral LCIS (ILC + LCIS) and those with pure ILC without a histologically detected co-occurring ipsilateral LCIS (ILC alone). We obtained data on demographics, pathologic tumour size (pT), pathologic lymph node (pN) involvement, estrogen (ER), progesterone (PR) receptor status, HER2 status, Ki67, treatment received, distant recurrence-free and overall survival (DRFS, OS). RESULTS: We identified 4217 patients with stage I-III ILC treated at MD Anderson between 1966 and 2021. 45% of cases (n = 1881) had co-existing LCIS. Statistically and numerically, ILC alone tended to associate with pT4 and pN3 stage (P < 0.001), ER/PR negativity (P = 0.0002), HER2 positivity (P = 0.010), higher Ki67 (P = 0.005), non-classical ILC subtype (P = 0.04) and more exposure to neoadjuvant chemotherapy (P = 0.0002) compared to the ILC + LCIS group. The median follow-up time was 6.5 years. Patients with ILC + LCIS had better median DRFS (16.8 versus 10.1 years, Hazard ratio [HR] 0.55, 95% confidence interval [CI] 0.50-0.60, P < 0.0001) and better median OS (18.9 versus 13.7 years, HR 0.62, 95% CI 0.56-0.69; P < 0.0001). Multivariate analysis showed the absence of LCIS to be an independent poor prognostic factor along with a higher pT stage and higher pN stage for DRFS and OS. CONCLUSION: The findings of this study suggests that the absence of ipsilateral LCIS with ILC is an independent poor prognostic factor and that further studies are warranted to understand this phenomenon.

Targeting CXCR4 abrogates resistance to trastuzumab by blocking cell cycle progression and synergizes with docetaxel in breast cancer treatment.

Background: Although trastuzumab and other HER2-targeted therapies have significantly improved survival in patients with HER2 overexpressed or amplified (HER2+) breast cancer, a significant proportion of patients do not respond or eventually develop clinical resistance. Strategies to reverse trastuzumab resistance remain a high clinical priority. We were the first to report the role of CXCR4 in trastuzumab resistance. The present study aims to explore the therapeutic potential of targeting CXCR4 and better understand the associated mechanisms. Methods: Immunofluorescent staining, confocal microscopy analysis, and immunoblotting were used to analyze CXCR4 expression. BrdU incorporation assays and flow cytometry were used to analyze dynamic CXCR4expression. Three-dimensional co-culture (tumor cells/ breast cancer-associated fibroblasts / human peripheral blood mononuclear cells) or antibody-dependent cellular cytotoxicity assay was used to mimic human tumor microenvironment, which is necessary for testing therapeutic effect of CXCR4 inhibitor or trastuzumab. The FDA-approved CXCR4 antagonist AMD3100, trastuzumab, and docetaxel chemotherapy were used to evaluate therapeutic efficacy in vitro and in vivo. Reverse phase protein array and immunoblotting were used to discern the associated molecular mechanisms. Results: Using multiple cell lines and patient breast cancer samples we confirmed CXCR4 drives trastuzumab resistance in HER2+ breast cancer and further demonstrated that the increased CXCR4 expression in trastuzumab-resistant cells is associated with cell cycle progression with a peak in the G2/M phases. Blocking CXCR4 with AMD3100 inhibits cell proliferation by downregulating mediators of G2-M transition, leading to G2/M arrest and abnormal mitosis. Using multiple trastuzumab-resistant cell lines and an in vivo established trastuzumab-resistant xenograft mouse model, we demonstrated that targeting CXCR4 with AMD3100 suppresses tumor growth in vitro and in vivo, and synergizes with docetaxel. Conclusions: Our findings support CXCR4 as a novel therapeutic target and a predictive biomarker for trastuzumab resistance in HER2+ breast cancer.

Histology-based survival outcomes in hormone receptor-positive metastatic breast cancer treated with targeted therapies.

The addition of targeted therapies (TT) to endocrine therapy (ET) has improved the outcomes of patients with HR-positive, HER2-negative metastatic breast cancer (mBC). However, it is unknown whether patients with invasive lobular carcinoma (ILC) or mixed invasive ductal and lobular carcinoma (mixed) histologies experience the same magnitude of benefit from this therapy as those with invasive ductal carcinoma (IDC). We aim to determine whether patients with IDC, ILC, and mixed HR+/HER2- mBC derive similar benefit from the addition of cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6is), mammalian target of rapamycin inhibitor (mTORi), and phosphoinositide 3-kinase inhibitor (PI3Ki) to ET in HR+/HER2- mBC. We conducted an observational, population-based investigation using data from the MD Anderson prospectively collected database. We conducted a histology-based analysis of progression-free survival (PFS) and overall survival (OS) durations in 3784 patients with HR+/HER2- mBC who were treated with TT plus ET between January 1, 2010, and December 31, 2021. Out of the 3784 patients, 2975 were included in the final analysis. Of these, 2249 received CDK4/6is (81% IDC, 15% ILC, and 4% mixed), 1027 received everolimus (82% IDC, 14% ILC, and 4% mixed) and 49 received alpelisib (81% IDC and 19% ILC). The addition of targeted therapy to ET did not result in statistically significant differences in PFS or OS duration among patients with IDC, ILC, and mixed HR+/HER2- mBC. We concluded that for patients with HR+/HER2- mBC, the addition of TT to ET leads to a similar magnitude of benefit, irrespective of histology.

Incidence and impact of brain metastasis in patients with hereditary BRCA1 or BRCA2 mutated invasive breast cancer.

Patients with hereditary mutations in BRCA1 or BRCA2 (gBRCA1/2) and breast cancer have distinct tumor biology, and encompass a predilection for brain metastasis (BM). We looked into baseline risk of BMs among gBRCA1/2 patients. Patients with gBRCA1/2, stage I-III invasive breast cancer seen between 2000-2017 with parenchymal BMs. Among gBRCA1 with distant breast cancer recurrence, 34 of 76 (44.7%) were diagnosed with brain metastases compared to 7 of 42 (16.7%) patients with gBRCA2. In the comparator group, 65 of 182 (35.7%) noncarrier triple-negative breast cancer (TNBC) and a distant recurrence experienced BM's. In a competitive risk analysis using death as a competing factor, the cumulative incidence of BMs was similar between gBRCA1 and noncarrier TNBC patients. The time from primary breast cancer diagnosis to detection of BMs was similar between gBRCA1 and noncarrier TNBC patients (2.4 vs 2.2 years). Survival was poor after BMs (7.8 months for gBRCA1 patients vs. 6.2 months for TNBC noncarriers). Brain was a more common site of initial distant recurrence in gBRCA1 patients versus TNBC noncarriers (26.3% vs. 12.1%). Importantly, the presence of BMs, adversely impacted overall survival across groups (HR 1.68 (95% CI 1.12-2.53), hazard ratio for death if a patient had BMs at the time of initial breast cancer recurrence vs. not). In conclusion, breast cancer BMs is common and is similarly frequent among gBRCA1 and noncarrier patients with recurrent TNBC. Our study highlights the importance of improving the prevention and treatment of BMs in patients with TNBC, gBRCA1 carriers, and noncarriers.

Targeting Metabolic Adaptations in the Breast Cancer-Liver Metastatic Niche Using Dietary Approaches to Improve Endocrine Therapy Efficacy.

Estrogen receptor-positive (ER+) metastatic tumors contribute to nearly 70% of breast cancer-related deaths. Most patients with ER+ metastatic breast cancer (MBC) undergo treatment with the estrogen receptor antagonist fulvestrant as standard of care. Yet, among such patients, metastasis in liver is associated with reduced overall survival compared with other metastasis sites. The factors underlying the reduced responsiveness of liver metastases to ER-targeting agents remain unknown, impeding the development of more effective treatment approaches to improve outcomes for patients with ER+ liver metastases. We therefore evaluated site-specific changes in MBC cells and determined the mechanisms through which the liver metastatic niche specifically influences ER+ tumor metabolism and drug resistance. We characterized ER activity of MBC cells both in vitro, using a novel system of tissue-specific extracellular matrix hydrogels representing the stroma of ER+ tumor metastatic sites (liver, lung, and bone), and in vivo, in liver and lung metastasis mouse models. ER+ metastatic liver tumors and MBC cells grown in liver hydrogels displayed upregulated expression of glucose metabolism enzymes in response to fulvestrant. Furthermore, differential ERα activity, but not expression, was detected in liver hydrogels. In vivo, increased glucose metabolism led to increased glycogen deposition in liver metastatic tumors, while a fasting-mimicking diet increased efficacy of fulvestrant treatment to reduce the metastatic burden. Our findings identify a novel mechanism of endocrine resistance driven by the liver tumor microenvironment. IMPLICATIONS: These results may guide the development of dietary strategies to circumvent drug resistance in liver metastasis, with potential applicability in other metastatic diseases.

Long-Term Survival of De Novo Stage IV Human Epidermal Growth Receptor 2 (HER2) Positive Breast Cancers Treated with HER2-Targeted Therapy.

BACKGROUND: An increasing proportion of human epidermal growth receptor 2 (HER2) positive (HER2+) metastatic breast cancer (MBC) is diagnosed as de novo stage IV disease. We hypothesize that a subset of these patients who achieve no evidence of disease (NED) status after multimodality HER2-targeted treatments may have prolonged progression-free survival (PFS) and overall survival (OS). MATERIALS AND METHODS: Patients with de novo stage IV, HER2+ MBC (n = 483) diagnosed between 1998 and 2015 were identified at two institutions (Yale and MD Anderson Cancer Centers). Clinical variables, treatment details, and survival outcomes were compared between those who achieved NED and those who did not. RESULTS: All patients received trastuzumab, and 20% also received pertuzumab as first-line therapy. The median OS was 5.5 years (95% confidence interval [Cl]: 4.8-6.2). Sixty-three patients (13.0%) achieved NED; their PFS and OS rates were 100% and 98% (95% CI: 94.6%-100%), respectively, at 5 years and remained the same at 10 years. For patients with no NED (n = 420), the PFS and OS rates were 12% (95% CI: 4.5%-30.4%) and 45% (95% CI: 38.4%-52.0%) at 5 years and 0% and 4% (95% CI, 1.3%-13.2%) at 10 years, respectively. NED patients more frequently had solitary metastasis (79% vs. 51%, p = .005) and surgery to resect cancer (59% vs. 22%, p ≤ .001). In multivariate analysis, NED status (hazard ratio [HR]: 0.014, p = .0002) and estrogen receptor positive status (HR: 0.72; p = .04) were associated with prolonged OS. CONCLUSION: Among patients with de novo stage IV, HER2+ MBC, those who achieve NED status have a very high PFS and OS. Further randomized studies are required to fully understand the impact of systemic or locoregional therapy on achieving these excellent long-term outcomes. IMPLICATIONS FOR PRACTICE: In this retrospective review at two institutions, it was demonstrated that 13% of patients with de novo stage IV, human epidermal growth receptor 2 positive metastatic breast cancer achieved no evidence of disease (NED) status with trastuzumab-based therapy plus/minus local therapies, and these patients had a very high progression-free survival (100%) and overall survival (98%) at both the 5- and 10-year time points. Achieving NED status may be an important therapeutic goal. However, further randomized studies are required to fully understand the impact of systemic or locoregional therapy on achieving these excellent long-term outcomes.

T-DM1 Activity in Metastatic Human Epidermal Growth Factor Receptor 2-Positive Breast Cancers That Received Prior Therapy With Trastuzumab and Pertuzumab.

Purpose Ado-trastuzumab emtansine (T-DM1) is currently approved for treatment in patients with human epidermal growth factor receptor 2 (HER2)-positive, metastatic breast cancer (MBC) who previously received trastuzumab and a taxane. However, there are no data on the activity of T-DM1 in patients who received prior pertuzumab, which is now included as standard first-line therapy. The goal of this study was to assess the efficacy of T-DM1 in routine clinical practice in a contemporary patient population that received both prior trastuzumab and pertuzumab. Patients and Methods We identified all patients with HER2-positive MBC who received T-DM1 after trastuzumab and pertuzumab between March 1, 2013, and July 15, 2015, via electronic pharmacy records and departmental databases at three institutions: MD Anderson Cancer Center, Smilow Cancer Hospital at Yale, and The James Cancer Hospital at the Ohio State University. We reviewed medical records of each case to confirm treatment sequencing and outcome. Results Of patients, 82 were identified and 78 were available for outcome analysis; 32% received T-DM1 as first- and second-line line therapy, and 48% received it as fourth-line treatment or later. Rate of prolonged duration on therapy, defined as duration on therapy ≥ 6 months, was 30.8% (95% CI, 20.6% to 41.1%), and tumor response rate was 17.9% (95% CI, 9.4% to 26.4%). Median duration on therapy was 4.0 months (95% CI, 2.7 to 5.1; range, 0 to 22.5 months). T-DM1 was discontinued for disease progression in 84% of patients and for toxicity in 10%. Conclusion Tumor response rates were lower than in prior reports of trastuzumab-resistant, HER2-positive MBC, but one third of patients received therapy with T-DM1 for ≥ 6 months, which suggests a clinically relevant benefit in patients who received prior pertuzumab.