Resistance to abemaciclib is associated with increased metastatic potential and lysosomal protein deregulation in breast cancer cells.

Cyclin dependent kinase 4 and 6 inhibitors such as abemaciclib are routinely used to treat metastatic estrogen receptor positive (ER+) breast cancer. However, adaptive mechanisms inhibit their effectiveness and allow for disease progression. Using ER+ breast cancer cell models, we show that acquired resistance to abemaciclib is accompanied by increase in metastatic potential. Mass spectrometry-based proteomics from abemaciclib sensitive and resistant cells showed that lysosomal proteins including CTSD (cathepsin D), cathepsin A and CD68 were significantly increased in resistant cells. Combination of abemaciclib and a lysosomal destabilizer, such as hydroxychloroquine (HCQ) or bafilomycin A1, resensitized resistant cells to abemaciclib. Also, combination of abemaciclib and HCQ decreased migration and invasive potential and increased lysosomal membrane permeability in resistant cells. Prosurvival B cell lymphoma 2 (BCL2) protein levels were elevated in resistant cells, and a triple treatment with abemaciclib, HCQ, and BCL2 inhibitor, venetoclax, significantly inhibited cell growth compared to treatment with abemaciclib and HCQ. Furthermore, resistant cells showed increased levels of Transcription Factor EB (TFEB), a master regulator of lysosomal-autophagy genes, and siRNA mediated knockdown of TFEB decreased invasion in resistant cells. TFEB was found to be mutated in a subset of invasive human breast cancer samples, and overall survival analysis in ER+, lymph node-positive breast cancer showed that increased TFEB expression correlated with decreased survival. Collectively, we show that acquired resistance to abemaciclib leads to increased metastatic potential and increased levels of protumorigenic lysosomal proteins. Therefore, the lysosomal pathway could be a therapeutic target in advanced ER+ breast cancer.

Heparanase Blockade as a Novel Dual-Targeting Therapy for COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused over 5 million deaths worldwide. Pneumonia and systemic inflammation contribute to its high mortality. Many viruses use heparan sulfate proteoglycans as coreceptors for viral entry, and heparanase (HPSE) is a known regulator of both viral entry and inflammatory cytokines. We evaluated the heparanase inhibitor Roneparstat, a modified heparin with minimum anticoagulant activity, in pathophysiology and therapy for COVID-19. We found that Roneparstat significantly decreased the infectivity of SARS-CoV-2, SARS-CoV-1, and retroviruses (human T-lymphotropic virus 1 [HTLV-1] and HIV-1) in vitro. Single-cell RNA sequencing (scRNA-seq) analysis of cells from the bronchoalveolar lavage fluid of COVID-19 patients revealed a marked increase in HPSE gene expression in CD68+ macrophages compared to healthy controls. Elevated levels of HPSE expression in macrophages correlated with the severity of COVID-19 and the expression of inflammatory cytokine genes, including IL6, TNF, IL1B, and CCL2. In line with this finding, we found a marked induction of HPSE and numerous inflammatory cytokines in human macrophages challenged with SARS-CoV-2 S1 protein. Treatment with Roneparstat significantly attenuated SARS-CoV-2 S1 protein-mediated inflammatory cytokine release from human macrophages, through disruption of NF-κB signaling. HPSE knockdown in a macrophage cell line also showed diminished inflammatory cytokine production during S1 protein challenge. Taken together, this study provides a proof of concept that heparanase is a target for SARS-CoV-2-mediated pathogenesis and that Roneparstat may serve as a dual-targeted therapy to reduce viral infection and inflammation in COVID-19. IMPORTANCE The complex pathogenesis of COVID-19 consists of two major pathological phases: an initial infection phase elicited by SARS-CoV-2 entry and replication and an inflammation phase that could lead to tissue damage, which can evolve into acute respiratory failure or even death. While the development and deployment of vaccines are ongoing, effective therapy for COVID-19 is still urgently needed. In this study, we explored HPSE blockade with Roneparstat, a phase I clinically tested HPSE inhibitor, in the context of COVID-19 pathogenesis. Treatment with Roneparstat showed wide-spectrum anti-infection activities against SARS-CoV-2, HTLV-1, and HIV-1 in vitro. In addition, HPSE blockade with Roneparstat significantly attenuated SARS-CoV-2 S1 protein-induced inflammatory cytokine release from human macrophages through disruption of NF-κB signaling. Together, this study provides a proof of principle for the use of Roneparstat as a dual-targeting therapy for COVID-19 to decrease viral infection and dampen the proinflammatory immune response mediated by macrophages.

Targeting primary and metastatic uveal melanoma with a G protein inhibitor.

Uveal melanoma (UM) is the most common intraocular tumor in adults. Nearly half of UM patients develop metastatic disease and often succumb within months because effective therapy is lacking. A novel therapeutic approach has been suggested by the discovery that UM cell lines driven by mutant constitutively active Gq or G11 can be targeted by FR900359 (FR) or YM-254890, which are bioavailable, selective inhibitors of the Gq/11/14 subfamily of heterotrimeric G proteins. Here, we have addressed the therapeutic potential of FR for UM. We found that FR inhibited all oncogenic Gq/11 mutants reported in UM. FR arrested growth of all Gq/11-driven UM cell lines tested, but induced apoptosis only in a few. Similarly, FR inhibited growth of, but did not efficiently kill, UM tumor cells from biopsies of primary or metastatic tumors. FR evoked melanocytic redifferentiation of UM tumor cells with low (class 1), but not high (class 2), metastatic potential. FR administered systemically below its LD50 strongly inhibited growth of PDX-derived class 1 and class 2 UM tumors in mouse xenograft models and reduced blood pressure transiently. FR did not regress xenografted UM tumors or significantly affect heart rate, liver function, hematopoiesis, or behavior. These results indicated the existence of a therapeutic window in which FR can be explored for treating UM and potentially other diseases caused by constitutively active Gq/11.

In Vivo Tumorigenesis, Osteolytic Sarcomas, and Tumorigenic Cell Lines from Transgenic Mice Expressing the Human T-Lymphotropic Virus Type 1 (HTLV-1) Tax Viral Oncogene.

Human T-lymphotropic virus type 1 (HTLV-1) causes adult T-cell leukemia, a disease commonly associated with hypercalcemia and osteolysis. There is no effective treatment for HTLV-1, and the osteolytic mechanisms are not fully understood. Mice expressing the HTLV-1 oncogene Tax, driven by the human granzyme B promoter (Tax+), develop osteolytic tumors. To investigate the progression of the bone-invasive malignancies, wild-type, Tax+, and Tax+/interferon-γ-/- mice were assessed using necropsy, histologic examination, IHC analysis, flow cytometry, and advanced imaging. Tax+ and Tax+/interferon-γ-/- malignancies of the ear, tail, and foot comprised poorly differentiated, round to spindle-shaped cells with prominent neutrophilic infiltrates. Tail tumors originated from muscle, nerve, and/or tendon sheaths, with frequent invasion into adjacent bone. F4/80+ and anti-mouse CD11b (Mac-1)+ histiocytic cells predominated within the tumors. Three Tax+/interferon-γ-/- cell lines were generated for in vivo allografts, in vitro gene expression and bone resorption assays. Two cell lines were of monocyte/macrophage origin, and tumors formed in vivo in all three. Differences in Pthrp, Il6, Il1a, Il1b, and Csf3 expression in vitro were correlated with differences in in vivo plasma calcium levels, tumor growth, metastasis, and neutrophilic inflammation. Tax+ mouse tumors were classified as bone-invasive histiocytic sarcomas. The cell lines are ideal for further examination of the role of HTLV-1 Tax in osteolytic tumor formation and the development of hypercalcemia and tumor-associated inflammation.

Long-term outcome of (neo)adjuvant zoledronic acid therapy in locally advanced breast cancer.

PURPOSE: The role of zoledronic acid (ZOL), a bone-targeted bisphosphonate, in the treatment of patients with breast cancer remains an active area of study. Here, we report the long-term outcomes of a randomized placebo-controlled phase II clinical trial in which ZOL treatment was added to neoadjuvant chemotherapy in women with locally advanced breast cancer. METHODS: 120 women with clinical stage II-III (≥ T2 and/or ≥ N1) newly diagnosed breast cancer were randomized to receive either 4 mg intravenous ZOL every 3 weeks for 1 year (17 total doses) beginning with the first dose of neoadjuvant chemotherapy, or chemotherapy alone. Clinical endpoints included time to recurrence (TTR), time to bone recurrence (TTBR), time to non-bone recurrence (TTNBR), breast cancer survival (BCS) and overall survival (OS). RESULTS: With a median follow-up interval of 14.4 years, there were no significant differences in any of the clinical endpoints studied between the control and ZOL groups in the overall study population. However, ER+/HER2- patients younger than age 45 who were treated with ZOL had significantly worse TTR and TTNBR with a trend towards worse TTBR, BCS and OS (TTR: P = 0.024, HR 6.05 [1.26-29.1]; TTNBR: P = 0.026, HR 6.94 [1.26-38.1]; TTBR: P = 0.054, HR 6.01 [0.97-37.1]; BCS: P = 0.138, HR 4.43 [0.62-31.7]; OS: P = 0.138, HR 4.43 [0.62-31.7]). These differences were not seen in older ER+/HER2- patients or triple-negative patients of any age. CONCLUSION: Addition of ZOL to neoadjuvant therapy did not significantly affect clinical outcomes in the overall study population but was associated with increased extra-skeletal recurrence and a trend towards worse survival in ER+/HER2- patients younger than age 45. These findings suggest caution when using zoledronic acid in young, premenopausal women with locally advanced breast cancer and warrant further investigation. Clinical Trial Registration Number NCT00242203, Date of Registration: 10/17/2005.

Mutation profile differences in younger and older patients with advanced breast cancer using circulating tumor DNA (ctDNA).

PURPOSE: Little is known regarding the mutation profiles of ctDNA in the older adult breast cancer population. The objective of this study is to assess differences in mutation profiles in the older adult breast cancer population using a ctDNA assay as well as assess utilization of testing results. METHODS: Patients with advanced breast cancer underwent molecular profiling using a plasma-based ctDNA NGS assay (Guardant360) between 5/2015 and 10/2019 at Siteman Cancer Center. The profiling results of a multi-institutional database of patients with advanced breast cancer who had undergone molecular profiling were obtained. Associations between mutations and age group (≥ 65 vs. < 65) were examined using a Fisher's exact test. RESULTS: In the single-institutional cohort, 148 patients (69.2%) were < 65 years old and 66 patients (30.8%) ≥ 65 years old. ATM, BRAF, and PIK3CA mutations were found more frequently in older patients with ER + HER2- breast cancers (p < 0.01). In the multi-institutional cohort, 5367 (61.1%) were < 65 years old and 3417 (38.9%) ≥ 65 years old. ATM, PIK3CA, and TP53 mutations were more common in the older cohort (p < 0.0001) and MYC and GATA3 mutations were less common in the older cohort (p < 0.0001). CtDNA testing influenced next-line treatment management in 40 (19.8%) patients in the single-institutional cohort. CONCLUSION: When controlling for subtype, results from a single institution were similar to the multi-institutional cohort showing that ATM and PIK3CA were more common in older adults. These data suggest there may be additional molecular differences in older adults with advanced breast cancers.

Immunogenomic profiling and pathological response results from a clinical trial of docetaxel and carboplatin in triple-negative breast cancer.

PURPOSE: Patients with triple-negative breast cancer (TNBC) who do not achieve pathological complete response (pCR) following neoadjuvant chemotherapy have a high risk of recurrence and death. Molecular characterization may identify patients unlikely to achieve pCR. This neoadjuvant trial was conducted to determine the pCR rate with docetaxel and carboplatin and to identify molecular alterations and/or immune gene signatures predicting pCR. EXPERIMENTAL DESIGN: Patients with clinical stages II/III TNBC received 6 cycles of docetaxel and carboplatin. The primary objective was to determine if neoadjuvant docetaxel and carboplatin would increase the pCR rate in TNBC compared to historical expectations. We performed whole-exome sequencing (WES) and immune profiling on pre-treatment tumor samples to identify alterations that may predict pCR. Thirteen matching on-treatment samples were also analyzed to assess changes in molecular profiles. RESULTS: Fifty-eight of 127 (45.7%) patients achieved pCR. There was a non-significant trend toward higher mutation burden for patients with residual cancer burden (RCB) 0/I versus RCB II/III (median 80 versus 68 variants, p 0.88). TP53 was the most frequently mutated gene, observed in 85.7% of tumors. EGFR, RB1, RAD51AP2, SDK2, L1CAM, KPRP, PCDHA1, CACNA1S, CFAP58, COL22A1, and COL4A5 mutations were observed almost exclusively in pre-treatment samples from patients who achieved pCR. Seven mutations in PCDHA1 were observed in pre-treatment samples from patients who did not achieve pCR. Several immune gene signatures including IDO1, PD-L1, interferon gamma signaling, CTLA4, cytotoxicity, tumor inflammation signature, inflammatory chemokines, cytotoxic cells, lymphoid, PD-L2, exhausted CD8, Tregs, and immunoproteasome were upregulated in pre-treatment samples from patients who achieved pCR. CONCLUSION: Neoadjuvant docetaxel and carboplatin resulted in a pCR of 45.7%. WES and immune profiling differentiated patients with and without pCR. TRIAL REGISTRATION: Clinical trial information: NCT02124902, Registered 24 April 2014 & NCT02547987, Registered 10 September 2015.

The ß3-integrin endothelial adhesome regulates microtubule-dependent cell migration.

Integrin ß3 is seen as a key anti-angiogenic target for cancer treatment due to its expression on neovasculature, but the role it plays in the process is complex; whether it is pro- or anti-angiogenic depends on the context in which it is expressed. To understand precisely ß3's role in regulating integrin adhesion complexes in endothelial cells, we characterised, by mass spectrometry, the ß3-dependent adhesome. We show that depletion of ß3-integrin in this cell type leads to changes in microtubule behaviour that control cell migration. ß3-integrin regulates microtubule stability in endothelial cells through Rcc2/Anxa2-driven control of active Rac1 localisation. Our findings reveal that angiogenic processes, both in vitro and in vivo, are more sensitive to microtubule targeting agents when ß3-integrin levels are reduced.

Assessing the effectiveness of the National Comprehensive Cancer Network genetic testing guidelines in identifying African American breast cancer patients with deleterious genetic mutations.

PURPOSE: Approximately, 10% of breast cancers are hereditary. Identifying women at high risk for hereditary breast and ovarian cancer allows for early detection, prevention, and individualized disease management for those diagnosed with breast cancer. There is limited data about breast cancer genetic risks among African Americans as the majority of the large studies have been conducted in European Americans. We examined the distribution of deleterious genetic mutations in African American breast cancer patients, and evaluated the effectiveness of the National Comprehensive Cancer Network (NCCN) guidelines for identifying African American women at high risk for deleterious genetic mutations. METHODS: African American participants with breast cancer underwent an interview regarding health and family history, and a 30-gene saliva test. Medical records were accessed to determine whether participants had received prior genetic testing as part of usual care, results of previous testing, and cancer characteristics. RESULTS: Two hundred and fifty participants were enrolled between February 2016 and May 2018. Twenty (8.0%) had a deleterious mutation in one of the 30 genes; BRCA2 had the highest frequency (40.0%). 187 (74.8%) met eligibility for testing based on NCCN guidelines. Only 110 (58.8%) of participants eligible for genetic testing, according to guidelines, had received prior testing as part of routine care. Using the 30-gene test, we identified deleterious mutations in 17 of 187 (9.1%) of those who met NCCN criteria for testing, and three of 63 (4.8%) of those who did not meet criteria for testing nonetheless had a deleterious mutation associated with breast cancer. CONCLUSIONS: Our results indicate that a large proportion of African American breast cancer patients who meet criteria for genetic testing do not receive it as part of routine care. Even in women who do not meet testing guidelines, nearly 5% have a known deleterious mutation associated with breast cancer.

Retrospective Analysis of Treatment Patterns and Effectiveness of Palbociclib and Subsequent Regimens in Metastatic Breast Cancer.

Background: Cyclin-dependent kinase (CDK) 4/6 inhibitors are now the standard of care for hormone receptor-positive (HR+), HER2-negative (HER-) metastatic breast cancer (MBC). However, guidelines are lacking regarding their optimal sequencing with other available agents. This study examines physician practice patterns and treatment outcomes of palbociclib and subsequent therapies in a real-world setting. Methods: A retrospective chart review was conducted for consecutive patients with MBC who received palbociclib between February 2015 and August 2017 at the Alvin J. Siteman Cancer Center. Kaplan-Meier method was used to generate time-to-event curves and estimate median progression-free survival (mPFS). Log-rank test was used to compare differences. Results: A total of 200 patients, with a median age of 59.4 years and a follow-up of 19.5 months, were included. Palbociclib was most frequently combined with letrozole (73.5%), followed by fulvestrant (25%), anastrozole (1%), and tamoxifen (0.5%). Most patients received palbociclib in the endocrine-resistant setting (n=42, n=50, and n=108 in the first-, second-, and subsequent-line settings, respectively), and the fraction of patients receiving palbociclib as first- or second-line therapy increased in recent months (P=.0428). mPFS was 20.7, 12.8, and 4.0 months with palbociclib administered in the first-, second-, and subsequent-line settings, respectively (P<.0001). Incidences of grade 3/4 neutropenia (41.5%) and dose reductions (29%) were comparable to reports in the literature. Among patients whose disease progressed on palbociclib (n=104), the most frequent next-line treatment was capecitabine (n=21), followed by eribulin (n=16), nab-paclitaxel (n=15), and exemestane + everolimus (n=12). mPFS with hormone therapy alone or in combination with targeted agents (n=32) after first-, second-, and subsequent-line palbociclib was 17.0, 9.3, and 4.2 months, respectively (P=.04). mPFS with chemotherapy (n=70) was not reached, 4.7, and 4.1 months after first-, second-, and subsequent-line palbociclib, respectively (P=.56). Conclusions: Palbociclib is effective for HR+/HER2- MBC in real-world practice. Hormone therapy alone or in combination with targeted agents remains an effective option after palbociclib progression.

Balixafortide plus eribulin in HER2-negative metastatic breast cancer: a phase 1, single-arm, dose-escalation trial.

BACKGROUND: The C-X-C chemokine receptor type 4 (CXCR4)-stromal cell-derived factor-1α (SDF-1α) axis regulates function and trafficking of immune cells and the tumour microenvironment. CXCR4 antagonists have been shown to enhance the activity of different anticancer treatments in preclinical models. We assessed the safety, tolerability, pharmacokinetics, and preliminary phase 1 activity of the CXCR4 antagonist, balixafortide, in combination with eribulin chemotherapy in patients with heavily pretreated, relapsed metastatic breast cancer. METHODS: This single-arm, dose-escalation, phase 1 trial enrolled patients at 11 sites in Spain and the USA. Eligible patients were women aged 18 years or older who had histologically confirmed HER2-negative metastatic breast cancer, evidence of tumour cell CXCR4 expression, an Eastern Cooperative Oncology Group performance status of 0 or 1, and who had previously received between one and three chemotherapy regimens for metastatic breast cancer, and at least one endocrine therapy if they had hormone receptor-positive disease, unless they were considered unsuitable for endocrine therapy. A standard 3+3 dose-escalation design was used, followed by an expanded cohort at the established maximum tolerated dose or highest dose if no dose-limiting toxicity was observed for the combination. After a treatment-related fatal adverse event in the first cohort who received 21-day cycles of treatment with eribulin and balixafortide, a protocol amendment modified the study design to be done in two parts. Patients enrolled to part 1 received an initial 28-day run-in cycle, with some cohorts receiving de-escalated doses of eribulin plus balixafortide to assess the safety and pharmacokinetics of the combination. The evaluation of part 1 did not confirm any dose-limiting toxicities or eribulin-balixafortide interactions, and therefore part 2 started enrolling patients to receive eribulin at the originally planned dose of 1·4 mg/m2 on days 2 and 9 of a 21-day cycle and balixafortide from a starting dose of 2 mg/kg with dose increments of 0·5 or 1 mg/kg on days 1-3 and 8-10 of the 21-day cycle. Both drugs were administered as intravenous infusions. All patients were to receive treatment until disease progression or unacceptable toxicity. The primary endpoints were dose-limiting toxicities and adverse events, and the establishment of a maximum tolerated dose or recommended phase 2 dose, and pharmacokinetic parameters. Safety analysis was done in all patients who received at least one dose of study treatment. Analysis of antitumour activity was done in all patients who received at least one full cycle of study treatment. The trial is registered at ClinicalTrials.gov, number NCT01837095, and is closed to accrual. FINDINGS: Between Jan 28, 2014, and Oct 4, 2016, 56 patients were enrolled into the trial. No dose-limiting toxicities were confirmed and the maximum tolerated dose was not reached. The highest dose was established as eribulin 1·4 mg/m2 on days 2 and 9, and balixafortide 5·5 mg/kg on days 1-3 and 8-10 of the 21-day cycle. Objective responses (all partial responses) were observed in 16 (30%; 95% CI 18-44) of 54 patients who were evaluable for antitumour activity. The most common treatment-emergent adverse events of any grade were fatigue (44 [79%] of 56 patients), neutropenia (32 [57%]), infusion-related reactions (27 [48%]), alopecia (26 [46%]), constipation (26 [46%]), and nausea (25 [45%]). Serious adverse events occurred in 21 (38%) of 56 patients, including febrile neutropenia in five (9%) of 56 patients, neutrophil count decrease in two (4%) patients, constipation in two (4%) patients, pneumonia in two (4%) patients, and urinary tract infection in three (5%) patients. Two (4%) of 56 patients died while receiving study treatment; one from septic shock and one from pneumonia. INTERPRETATION: The safety and tolerability of balixafortide plus eribulin seems to be similar to that of eribulin or balixafortide monotherapy, and the preliminary activity of the combination seems promising in patients with HER-negative metastatic breast cancer. The results suggest that balixafortide plus eribulin has potential to provide a new therapeutic option in heavily pretreated patients with metastatic breast cancer and warrants further investigation in randomised trials. FUNDING: Polyphor.

Differences in the mutational landscape of triple-negative breast cancer in African Americans and Caucasians.

BACKGROUND: Triple-negative breast cancer (TNBC) occurs at higher frequency in African Americans compared with Caucasians. It is unclear if the biology of TNBC is different in African American versus Caucasians. In this study, we sought to evaluate racial differences in the molecular pathology of TNBC. METHODS: Using data from The Cancer Genome Atlas, we identified TNBC patients with information on race. We analyzed differences in clinical characteristics, tumor somatic mutations, and gene expression patterns by race from whole exome and microarray data. RESULTS: 1104 patients were identified, of which 178 had TNBC. TNBC was more frequent in African Americans than Caucasians (33.3 vs 14.9%). Although more African Americans than Caucasians overall were classified as basal-like from PAM50 gene expression (34.8 vs 16.1%), no differences in the TNBC cohort were observed. Median tumor somatic mutation counts were higher in African Americans versus Caucasians (39.5 vs 34), but no racial differences in the mutation counts in TNBC were observed. Somatic mutation analysis revealed racial differences in specific high prevalence genes in all patients (TP53 46% in African Americans vs 27% in Caucasians; PIK3CA 23% in African Americans vs 34% in Caucasians; and MLL3 12% in African Americans vs 6% in Caucasians). TNBC patients did not have any specific high prevalence genes associated with racial differences. There were no racial differences in gene expression patterns in selected genes involved in breast cancer biology. Overall, African Americans had shorter TTP and worse DFS. Racial differences in clinical outcomes were not observed in TNBC. CONCLUSION: The mutational landscape of TNBC is similar between African Americans and Caucasians. The higher frequency of TNBC in African Americans is therefore not associated with a different genomic profile of commonly established tumor regulatory pathway genes. Other modifiable factors may exist that contribute to the racial disparity in TNBC.

Acute depletion of endothelial ß3-integrin transiently inhibits tumor growth and angiogenesis in mice.

RATIONALE: The dramatic upregulation of αvß3-integrin that occurs in the vasculature during tumor growth has long suggested that the endothelial expression of this molecule is an ideal target for antiangiogenic therapy to treat cancer. This discovery led to the development of small-molecule inhibitors directed against αvß3-integrin that are currently in clinical trials. In 2002, we reported that ß3-integrin-knockout mice exhibit enhanced tumor growth and angiogenesis. However, as ß3-integrin is expressed by a wide variety of cells, endothelial cell-specific contributions to tumor angiogenesis are muddied by the use of a global knockout of ß3-integrin function. OBJECTIVE: Our aim was to examine the endothelial-specific contribution ß3-integrin makes to tumor growth and angiogenesis. METHODS AND RESULTS: We have crossed ß3-integrin-floxed (ß3-floxed) mice to 2 endothelial-specific Cre models and examined angiogenic responses in vivo, ex vivo, and in vitro. We show that acute depletion of endothelial ß3-integrin inhibits tumor growth and angiogenesis preventatively, but not in already established tumors. However, the effects are transient, and long-term depletion of the molecule is ineffective. Furthermore, long-term depletion of the molecule correlates with many molecular changes, such as reduced levels of focal adhesion kinase expression and a misbalance in focal adhesion kinase phosphorylation, which may lead to a release from the inhibitory effects of decreased endothelial ß3-integrin expression. CONCLUSIONS: Our findings imply that timing and length of inhibition are critical factors that need to be considered when targeting the endothelial expression of ß3-integrin to inhibit tumor growth and angiogenesis.

Dual-therapy with αvß3-targeted Sn2 lipase-labile fumagillin-prodrug nanoparticles and zoledronic acid in the Vx2 rabbit tumor model.

Fumagillin, an unstable anti-angiogenesis mycotoxin, was synthesized into a stable lipase-labile prodrug and incorporated into integrin-targeted lipid-encapsulated nanoparticles (αvß3-Fum-PD NP). Dual anti-angiogenic therapy combining αvß3-Fum-PD NP with zoledronic acid (ZA), a long-acting osteoclast inhibitor with proposed anti-angiogenic effects, was evaluated. In vitro, αvß3-Fum-PD NP reduced (P<0.05) endothelial cell viability without impacting macrophage viability. ZA suppressed (P<0.05) macrophage viability at high dosages but not endothelial cell proliferation. 3D MR neovascular imaging of rabbit Vx2 tumors showed no effect with ZA, whereas αvß3-Fum-PD NP alone and with ZA decreased angiogenesis (P<0.05). Immunohistochemistry revealed decreased (P<0.05) microvascularity with αvß3-Fum-PD NP and ZA and further microvascular reduction (P<0.05) with dual-therapy. In vivo, ZA did not decrease tumor macrophage numbers nor cancer cell proliferation, whereas αvß3-Fum-PD-NPs reduced both measures. Dual-therapy with ZA and αvß3-Fum-PD-NP may provide enhanced neo-adjuvant utility if macrophage ZA uptake is increased. From the Clinical Editor: Although anti-angiogenesis is one of the treatment modalities in the fight against cancer, many cancers become resistant to VEGF pathway inhibitors. In this article, the authors investigated the use of dual therapy using fumagillin, integrin-targeted lipid-encapsulated nanoparticles (αvß3- Fum-PD NP) and zoledronic acid (ZA), in both in-vitro and in-vivo experiments. This combination approach may provide an insight to the design of future drugs against cancers.

Chemotherapy and the Extra-Tumor Immune Microenvironment: EXTRA-TIME.

SUMMARY: Understandably, conventional therapeutic strategies have focused on controlling primary tumors. We ask whether the cost of such strategies is actually an increased likelihood of metastatic relapse.

BCAR4 Expression as a Predictive Biomarker for Endocrine Therapy Resistance in Breast Cancer.

BACKGROUND: Breast cancer, particularly the estrogen receptor positive (ER+) subtype, remains a leading cause of cancer-related death among women. Endocrine therapy is the most effective treatment for ER+ breast cancer; however, the development of resistance presents a significant challenge. This study explored the role of the breast cancer antiestrogen resistance 4 (BCAR4) gene as a potential driver of resistance and a pivotal biomarker in breast cancer. PATIENTS AND METHODS: The researchers undertook a comprehensive analysis of 1743 patients spanning 6 independent cohorts. They examined the association of BCAR4 expression with patient outcomes across all breast cancer types and the PAM50 molecular subtypes. The relationship between elevated BCAR4 expression and resistance to endocrine therapy including AIs, the prevailing standard-of-care for endocrine therapy, was also investigated. RESULTS: This meta-analysis corroborated the link between BCAR4 expression and adverse outcomes as well as resistance to endocrine therapy in breast cancer. Notably, BCAR4 expression is clinically significant in luminal A and B subtypes. Additionally, an association between BCAR4 expression and resistance to AI treatment was discerned. CONCLUSION: This study expands on previous findings by demonstrating that BCAR4 expression is associated with resistance to newer therapies. The identification of patients with intrinsic resistance to hormone therapy is crucial to avoid ineffective treatment strategies. These findings contribute to our understanding of endocrine therapy resistance in breast cancer and could potentially guide the development of more effective treatment strategies.

HTLV-1 infected T cells cause bone loss via small extracellular vesicles.

Adult T cell leukemia (ATL), caused by infection with human T cell leukemia virus type 1 (HTLV-1), is often complicated by hypercalcemia and osteolytic lesions. Therefore, we studied the communication between patient-derived ATL cells (ATL-PDX) and HTLV-1 immortalized CD4+ T cell lines (HTLV/T) with osteoclasts and their effects on bone mass in mice. Intratibial inoculation of some HTLV/T lead to a profound local decrease in bone mass similar to marrow-replacing ATL-PDX, despite the fact that few HTLV/T cells persisted in the bone. To study the direct effect of HTLV/T and ATL-PDX on osteoclasts, supernatants were added to murine and human osteoclast precursors. ATL-PDX supernatants from hypercalcemic patients promoted formation of mature osteoclasts, while those from HTLV/T were variably stimulatory, but had largely consistent effects between human and murine cultures. Interestingly, this osteoclastic activity did not correlate with expression of osteoclastogenic cytokine RANKL, suggesting an alternative mechanism. HTLV/T and ATL-PDX produce small extracellular vesicles (sEV), known to facilitate HTLV-1 infection. We hypothesized that these sEV also mediate bone loss by targeting osteoclasts. We isolated sEV from both HTLV/T and ATL-PDX, and found they carried most of the activity found in supernatants. In contrast, sEV from uninfected activated T cells had little effect. Analysis of sEV (both active and inactive) by mass spectrometry and electron microscopy confirmed absence of RANKL and intact virus. Viral proteins Tax and Env were only present in sEV from the active, osteoclast-stimulatory group, along with increased representation of proteins involved in osteoclastogenesis and bone resorption. sEV injected over mouse calvaria in the presence of low dose RANKL caused more osteolysis than RANKL alone. Thus, HTLV-1 infection of T cells can cause release of sEV with strong osteolytic potential, providing a mechanism beyond RANKL production that modifies the bone microenvironment, even in the absence of overt leukemia.

Induction of complementary immunogenic necroptosis and apoptosis cell death pathways inhibits cancer metastasis and relapse.

Interactions of light-sensitive drugs and materials with Cerenkov radiation-emitting radiopharmaceuticals generate cytotoxic reactive oxygen species (ROS) to inhibit localized and disseminated cancer progression, but the cell death mechanisms underlying this radionuclide stimulated dynamic therapy (RaST) remain elusive. Using ROS-regenerative nanophotosensitizers coated with a tumor-targeting transferrin-titanocene complex (TiO2-TC-Tf) and radiolabeled 2-fluorodeoxyglucose (18FDG), we found that adherent dying cells maintained metabolic activity with increased membrane permeabilization. Mechanistic assessment of these cells revealed that RaST activated the expression of RIPK-1 and RIPK-3, which mediate necroptosis cell death. Subsequent recruitment of the nuclear factors kappa B and the executioner mixed lineage kinase domain-like pseudo kinase (MLKL) triggered plasma membrane permeabilization and pore formation, respectively, followed by the release of cytokines and immunogenic damage-associated molecular patterns (DAMPs). In immune-deficient breast cancer models with adequate stroma and growth factors that recapitulate the human tumor microenvironment, RaST failed to inhibit tumor progression and the ensuing lung metastasis. A similar aggressive tumor model in immunocompetent mice responded to RaST, achieving a remarkable partial response (PR) and complete response (CR) with no evidence of lung metastasis, suggesting active immune system engagement. RaST recruited antitumor CD11b+, CD11c+, and CD8b+ effector immune cells after initiating dual immunogenic apoptosis and necroptosis cell death pathways in responding tumors in vivo. Over time, cancer cells upregulated the expression of negative immune regulating cytokine (TGF-ß) and soluble immune checkpoints (sICP) to challenge RaST effect in the CR mice. Using a signal-amplifying cancer-imaging agent, LS301, we identified latent minimal residual disseminated tumors in the lymph nodes (LNs) of the CR group. Despite increased protumor immunogens in the CR mice, RaST prevented cancer relapse and metastasis through dynamic redistribution of ROS-regenerative TiO2 from bones at the early treatment stage to the spleen and LNs, maintaining active immunity against cancer progression and migration. This study reveals the immune-mechanistic underpinnings of RaST-mediated antitumor immune response and highlights immunogenic reprogramming of tumors in response to RaST. Overcoming apoptosis resistance through complementary necroptosis activation paves the way for strategic drug combinations to improve cancer treatment.

Frequency of Hepatic Metastatic Disease in Patients with Stage IV Breast Cancer Is Similar for Steatotic and Non-Steatotic Livers.

Background: Breast cancer is the most common non-cutaneous malignancy and the second leading cause of cancer mortality in the United States. Breast cancer is a heterogeneous disease; diagnosis at an early stage renders it potentially curable, whereas advanced metastatic disease carries a worse prognosis. Objectives: To investigate whether hepatic steatosis (HS) is associated with liver metastases in patients with newly diagnosed stage IV female breast cancer patients (either de novo metastatic breast cancer or recurrent metastatic breast cancer) using non-contrast computed tomography (CT) as a marker of HS. Design: Retrospective analysis. Methods: We retrospectively identified 168 patients with stage IV breast cancer with suitable imaging from a prospectively maintained oncologic database. Three radiologists manually defined hepatic regions of interest on non-contrast CT images, and attenuation data were extracted. HS was defined as a mean attenuation <48 Hounsfield units. The frequency of hepatic metastatic disease was calculated for patient with and without HS. Relationships between HS and various patient (age, body mass index, race) and tumor (hormone receptor status, HER2 status, tumor grade) characteristics were also analyzed. Results: There were 4 patients with liver metastasis in the HS group (41 patients) versus 20 patients with liver metastases in the non-HS group (127 patients). The difference in frequencies of liver metastases among patients with (9.8%) versus without (15.7%) hepatic steatosis (odds ratio = 1.72 [0.53-7.39]) was not statistically significant (P = .45). Body mass index was significantly higher (P = .01) among patients with hepatic steatosis (32.2 ± 7.3 vs 28.8 ± 7.1 kg/m2). Otherwise, there were no significant differences between patients with versus without HS with respect to regarding age, race, hormone receptor status, HER2 status, or tumor grade. Conclusion: The frequency of hepatic metastatic disease in patients with stage IV breast cancer is similar for steatotic and non-steatotic livers.

A phase II study of palbociclib plus letrozole plus trastuzumab as neoadjuvant treatment for clinical stages II and III ER+ HER2+ breast cancer (PALTAN).

Patients with ER+/HER2+ breast cancer (BC) are less likely to achieve pathological complete response (pCR) after chemotherapy with dual HER2 blockade than ER-/HER2+ BC. Endocrine therapy plus trastuzumab is effective in advanced ER+/HER2+ BC. Inhibition of CDK4/6 and HER2 results in synergistic cell proliferation reduction. We combined palbociclib, letrozole, and trastuzumab (PLT) as a chemotherapy-sparing regimen. We evaluated neoadjuvant PLT in early ER+/HER2+ BC. Primary endpoint was pCR after 16 weeks. Research biopsies were performed for whole exome and RNA sequencing, PAM50 subtyping, and Ki67 assessment for complete cell cycle arrest (CCCA: Ki67 ≤ 2.7%). After 26 patients, accrual stopped due to futility. pCR (residual cancer burden-RCB 0) was 7.7%, RCB 0/I was 38.5%. Grade (G) 3/4 treatment-emergent adverse events occurred in 19. Among these, G3/4 neutropenia was 50%, hypertension 26.9%, and leucopenia 7.7%. Analysis indicated CCCA in 85% at C1 day 15 (C1D15), compared to 27% at surgery after palbociclib was discontinued. Baseline PAM50 subtyping identified 31.2% HER2-E, 43.8% Luminal B, and 25% Luminal A. 161 genes were differentially expressed comparing C1D15 to baseline. MKI67, TK1, CCNB1, AURKB, and PLK1 were among the genes downregulated, consistent with CCCA at C1D15. Molecular Signatures Database gene-sets analyses demonstrated downregulated processes involved in proliferation, ER and mTORC1 signaling, and DNA damage repair at C1D15, consistent with the study drug's mechanisms of action. Neoadjuvant PLT showed a pCR of 7.7% and an RCB 0/I rate of 38.5%. RNA sequencing and Ki67 data indicated potent anti-proliferative effects of study treatments. ClinicalTrials.gov- NCT02907918.