Maintenance Pembrolizumab Therapy in Patients with Metastatic HER2-negative Breast Cancer with Prior Response to Chemotherapy.

PURPOSE: Accumulating toxicities hinder indefinite chemotherapy for many patients with metastatic/recurrent HER2-negative breast cancer. We conducted a phase II trial of pembrolizumab monotherapy following induction chemotherapy to determine the efficacy of maintenance immunotherapy in patients with metastatic HER2-negative inflammatory breast cancer (IBC) and non-IBC triple-negative breast cancer (TNBC) and a biomarker study. PATIENTS AND METHODS: Patients with a complete response, partial response, or stable disease (SD) after at least three cycles of chemotherapy for HER2-negative breast cancer received pembrolizumab, regardless of programmed death-ligand 1 expression. Pembrolizumab (200 mg) was administered every 3 weeks until disease progression, intolerable toxicity, or 2 years of pembrolizumab exposure. The endpoints included the 4-month disease control rate (DCR), progression-free survival (PFS), overall survival, and response biomarkers in the blood. RESULTS: Of 43 treated patients, 11 had metastatic IBC and 32 non-IBC TNBC. The 4-month DCR was 58.1% [95% confidence interval (CI), 43.4-72.9]. For all patients, the median PFS was 4.8 months (95% CI, 3.0-7.1 months). The toxicity profile was similar to the previous pembrolizumab monotherapy study. Patients with high T-cell clonality at baseline had a longer PFS with pembrolizumab treatment than did those with low T-cell clonality (10.4 vs. 3.6 months, P = 0.04). Patients who achieved SD also demonstrated a significant increase in T-cell clonality during therapy compared with those who did not achieve SD (20% vs. 5.9% mean increase, respectively; P = 0.04). CONCLUSIONS: Pembrolizumab monotherapy achieved durable treatment responses. Patients with a high baseline T-cell clonality had prolonged disease control with pembrolizumab.

Phenotypic Plasticity in Circulating Tumor Cells Is Associated with Poor Response to Therapy in Metastatic Breast Cancer Patients.

Circulating tumor cells (CTCs) are indicators of metastatic spread and progression. In a longitudinal, single-center trial of patients with metastatic breast cancer starting a new line of treatment, a microcavity array was used to enrich CTCs from 184 patients at up to 9 timepoints at 3-month intervals. CTCs were analyzed in parallel samples from the same blood draw by imaging and by gene expression profiling to capture CTC phenotypic plasticity. Enumeration of CTCs by image analysis relying primarily on epithelial markers from samples obtained before therapy or at 3-month follow-up identified the patients at the highest risk of progression. CTC counts decreased with therapy, and progressors had higher CTC counts than non-progressors. CTC count was prognostic primarily at the start of therapy in univariate and multivariate analyses but had less prognostic utility at 6 months to 1 year later. In contrast, gene expression, including both epithelial and mesenchymal markers, identified high-risk patients after 6-9 months of treatment, and progressors had a shift towards mesenchymal CTC gene expression on therapy. Cross-sectional analysis showed higher CTC-related gene expression in progressors 6-15 months after baseline. Furthermore, patients with higher CTC counts and CTC gene expression experienced more progression events. Longitudinal time-dependent multivariate analysis indicated that CTC count, triple-negative status, and CTC expression of FGFR1 significantly correlated with inferior progression-free survival while CTC count and triple-negative status correlated with inferior overall survival. This highlights the utility of protein-agnostic CTC enrichment and multimodality analysis to capture the heterogeneity of CTCs.

Emerging drug targets for triple-negative breast cancer: a guided tour of the preclinical landscape.

INTRODUCTION: Triple-negative breast cancer (TNBC) is the most fatal molecular subtype of breast cancer because of its aggressiveness and resistance to chemotherapy. FDA-approved therapies for TNBC are limited to poly(ADP-ribose) polymerase inhibitors, immune checkpoint inhibitors, and trophoblast cell surface antigen 2-targeted antibody-drug conjugate. Therefore, developing a novel effective targeted therapy for TNBC is an urgent unmet need. AREAS COVERED: In this narrative review, we discuss emerging targets for TNBC treatment discovered in early translational studies. We focus on cancer cell membrane molecules, hyperactive intracellular signaling pathways, and the tumor microenvironment (TME) based on their druggability, therapeutic potency, specificity to TNBC, and application in immunotherapy. EXPERT OPINION: The significant challenges in the identification and validation of TNBC-associated targets are 1) application of appropriate genetic, molecular, and immunological approaches for modulating the target, 2) establishment of a proper mouse model that accurately represents the human immune TME, 3) TNBC molecular heterogeneity, and 4) failure translation of preclinical findings to clinical practice. To overcome those difficulties, future research needs to apply novel technology, such as single-cell RNA sequencing, thermostable group II intron reverse transcriptase sequencing, and humanized mouse models. Further, combination treatment targeting multiple pathways in both the TNBC tumor and its TME is essential for effective disease control.

Seed- and Soil-Dependent Differences in Murine Breast Tumor Microenvironments Dictate Anti-PD-L1 IgG Delivery and Therapeutic Efficacy.

We sought to determine if Stephen Paget's "seed and soil" hypothesis of organ-preference patterns of cancer metastasis can explain the development of heterogeneity in a tumor microenvironment (TME) as well as immunotherapeutic delivery and efficacy. We established single-cell-derived clones (clones 1 and 16) from parental 4T1 murine breast cancer cells to create orthotopic primary and liver metastasis models to deconvolute polyclonal complexity cancer cells and the difference in TME-derived heterogeneities. Tumor-bearing mice were treated with anti-PD-L1 IgG or a control antibody, and immunofluorescent imaging and quantification were then performed to evaluate the therapeutic efficacy on tumor growth, the delivery of therapy to tumors, the development of blood vessels, the expression of PD-L1, the accumulation of immune cells, and the amount of coagulation inside tumors. The quantification showed an inverse correlation between the amount of delivered therapy and therapeutic efficacy in parental-cell-derived tumors. In contrast, tumors originating from clone 16 cells accumulated a significantly greater amount of therapy and responded better than clone-1-derived tumors. This difference was greater when tumors grew in the liver than the primary site. A similar trend was found in PD-L1 expression and immune cell accumulation. However, the change in the number of blood vessels was not significant. In addition, the amount of coagulation was more abundant in clone-1-derived tumors when compared to others. Thus, our findings reconfirmed the seed- and soil-dependent differences in PD-L1 expression, therapeutic delivery, immune cell accumulation, and tumor coagulation, which can constitute a heterogeneous delivery and response of immunotherapy in polyclonal tumors growing in different organs.

A phase II study of talimogene laherparepvec for patients with inoperable locoregional recurrence of breast cancer.

Talimogene laherparepvec (T-VEC) is an immunotherapy that generates local tumor lysis and systemic antitumor immune response. We studied the efficacy of intratumoral administration of T-VEC as monotherapy for inoperable locoregional recurrence of breast cancer. T-VEC was injected intratumorally at 106 PFU/mL on day 1 (cycle 1), 108 PFU/mL on day 22 (cycle 2), and 108 PFU/mL every 2 weeks thereafter (cycles ≥ 3). Nine patients were enrolled, 6 with only locoregional disease and 3 with both locoregional and distant disease. No patient completed the planned 10 cycles or achieved complete or partial response. The median number of cycles administered was 4 (range, 3-8). Seven patients withdrew prematurely because of uncontrolled disease progression, 1 withdrew after cycle 3 because of fatigue, and 1 withdrew after cycle 4 for reasons unrelated to study treatment. Median progression-free survival and overall survival were 77 days (95% CI, 63-NA) and 361 days (95% CI, 240-NA). Two patients received 8 cycles with clinically stable disease as the best response. The most common grade 2 or higher adverse event was injection site reaction (n = 7, 78%). Future studies could examine whether combining intratumoral T-VEC with concurrent systemic therapy produces better outcomes.

Inflammatory breast cancer appearance at presentation is associated with overall survival.

BACKGROUND: Inflammatory breast cancer (IBC) is a clinical diagnosis. Here, we examined the association of a "classic" triad of clinical signs, swollen involved breast, nipple change, and diffuse skin change, with overall survival (OS). METHOD: Breast medical photographs from patients enrolled on a prospective IBC registry were scored by two independent reviewers as classic (triad above), not classic, and difficult to assign. Chi-squared test, Fisher's exact test, and Wilcoxon rank-sum test were used to assess differences between patient groups. Kaplan-Meier estimates and the log-rank test and Cox proportional hazard regression were used to assess the OS. RESULTS: We analyzed 245 IBC patients with median age 54 (range 26-81), M0 versus M1 status (157 and 88 patients, respectively). The classic triad was significantly associated with smoking, post-menopausal status, and metastatic disease at presentation (p = 0.002, 0.013, and 0.035, respectively). Ten-year actuarial OS for not classic and difficult to assign were not significantly different and were grouped for further analyses. Ten-year OS was 29.7% among patients with the classic sign triad versus 57.2% for non-classic (p < 0.0001). The multivariate Cox regression model adjusting for clinical staging (p < 0.0001) and TNBC status (<0.0001) demonstrated classic presentation score significantly associated with poorer OS time (HR 2.6, 95% CI 1.7-3.9, p < 0.0001). CONCLUSIONS: A triad of classic IBC signs independently predicted OS in patients diagnosed with IBC. Further work is warranted to understand the biology related to clinical signs and further extend the understanding of physical examination findings in IBC.

Tumor Site-Dependent Transport Properties Determine Nanotherapeutics Delivery and Its Efficacy.

Insufficient delivery of systemically administered anticancer drugs to tumors can compromise therapeutic efficacy and develop drug delivery-based therapeutic resistance. Nanotherapeutics such as PEGylated liposomal doxorubicin (PLD) are designed to preferentially accumulate in tumors utilizing enhanced permeation and retention effect. However, their antitumor effects and resulting clinical outcomes are modest and heterogeneous among tumors. Here, we aimed to investigate whether the amount and efficacy of PLD delivered to tumors are tumor site dependent. We established orthotopic primary tumor or liver metastases models of murine breast cancer using 4 T1 cells. PLD showed significant therapeutic effects against tumors that grew in primary mammary sites but not in the liver. We found that differences in therapeutic efficacy were not because of the intrinsic biological resistance of cancer cells but rather were associated with tumor site-dependent differences in transport properties, such as the amount of PLD delivery, blood vessel function, relative vascular permeability, and mechanical pressure in tumors. Thus, transport properties in tumor is site dependent and can be used as phenotypic surrogate markers for tumor drug delivery and therapeutic efficacy.

Tumor progression effects on drug vector access to tumor-associated capillary bed.

Over the last decade, the benefits of drug vectors to treat cancer have been well recognized. However, drug delivery and vector distribution differences in tumor-associated capillary bed at different stages of disease progression are not well understood. To obtain further insights into drug vector distribution changes in vasculature during tumor progression, we combined intra-vital imaging of metastatic tumors in mice, microfluidics-based artificial tumor capillary models, and Computational Fluid Dynamics (CFD) modeling. Microfluidic and CFD circulation models were designed to mimic tumor progression by escalating flow complexity and chaoticity. We examined flow of 0.5 and 2µm spherical particles, and tested the effects of hematocrit on particle local accessibility to flow area of capillary beds by co-circulating red blood cells (RBC). Results showed that tumor progression modulated drug vector distribution in tumor-associated capillaries. Both particles shared 80-90% common flow area, while 0.5 and 2µm particles had 2-9% and 1-2% specific flow area, respectively. Interestingly, the effects of hematocrit on specific circulation area was opposite for 0.5 and 2µm particles. Dysfunctional capillaries with no flow, a result of tumor progression, limited access to all particles, while diffusion was shown to be the only prevailing transport mechanism. In view of drug vector distribution in tumors, independent of formulation and other pharmacokinetic aspects, our results suggest that the evolution of tumor vasculature during progression may influence drug delivery efficiency. Therefore, optimized drug vectors will need to consider primary vs metastatic tumor setting, or early vs late stage metastatic disease, when undergoing vector design.

Gemcitabine enhances the transport of nanovector-albumin-bound paclitaxel in gemcitabine-resistant pancreatic ductal adenocarcinoma.

The mechanism for improved therapeutic efficacy of the combination therapy with nanoparticle albumin-bound paclitaxel (nAb-PTX) and gemcitabine (gem) for pancreatic ductal adenocarcinoma (PDAC) has been ascribed to enhanced gem transport by nAb-PTX. Here, we used an orthotopic mouse model of gem-resistant human PDAC in which increasing gem transport would not improve the efficacy, thus revealing the importance of nAb-PTX transport. We aimed to evaluate therapeutic outcomes and transport of nAb-PTX to PDAC as a result of (1) encapsulating nAb-PTX in multistage nanovectors (MSV); (2) effect of gem on caveolin-1 expression. Treatment with MSV/nAb-PTX + gem was highly efficient in prolonging animal survival in comparison to other therapeutic regimens. MSV/nAb-PTX + gem also caused a substantial increase in tumor PTX accumulation, significantly reduced tumor growth and tumor cell proliferation, and increased apoptosis. Moreover, gem enhanced caveolin-1 expression in vitro and in vivo, thereby improving transport of nAb-PTX to PDAC. This data was confirmed by analysis of PDACs from patients who received gem-based neo-adjuvant chemotherapy. In conclusion, we found that nAb-PTX treatment of gem-resistant PDAC can be enhanced by (1) gem through up-regulation of caveolin-1 and (2) MSV through increasing accumulation of nAb-PTX in the tumor.

Clinical characteristics and outcome of bone-only metastasis in inflammatory and noninflammatory breast cancers.

BACKGROUND: Inflammatory breast cancer is a rare and aggressive presentation of breast cancer. Bone is a common metastatic site in breast cancer, and bone-only metastatic disease is clinically considered to have a better prognosis than visceral metastasis. However, bone-only metastasis in IBC (bone-only IBC) has not been compared with bone-only metastasis in non-IBC (bone-only non-IBC) in terms of clinical features and outcome. Because of the intrinsically aggressive nature of IBC, we hypothesized that bone-only IBC has a poorer prognosis than does bone-only non-IBC. PATIENTS AND METHODS: We retrospectively identified patients with stage III primary diagnosed breast cancer who, between January 1997 and December 2012, had a first recurrence located only in the bone. Among the 197 patients that we defined as a study cohort, 50 patients had IBC and 147 patients had non-IBC. Progression-free survival (PFS) and overall survival (OS) from the date of recurrence were estimated using the Kaplan-Meier method, and patient characteristic groups were compared using the log-rank test. RESULTS: OS did not differ significantly between the 2 groups (P = .2467), but a shorter PFS was seen in patients with bone-only IBC than in patients with bone-only non-IBC (P = .0357). Among patients with estrogen receptor (ER)-positive disease, a much shorter PFS was seen in bone-only IBC than in bone-only non-IBC (P = .0159). CONCLUSION: Bone-only IBC has a poorer prognosis than does bone-only non-IBC, particularly in those with ER-positive tumors. We might need to consider more aggressive intervention (e.g., chemotherapy) for IBC patients with ER-positive bone-only metastatic disease.

[A case of neurogenic pulmonary edema associated with epileptic seizure].

We report a case of neurogenic pulmonary edema associated with epileptic seizure. A 36-year-old woman had had several episodes of fainting and postictal respiratory failure, and since July 1998 had been admitted to a nearby hospital three times. On October 12, 1999, she was again admitted to a nearby hospital with the same symptom, and was transferred from that hospital to ours for evaluation of the recurrent respiratory disorder. Low-grade fever, mild leukocytosis, hypoxemia and bilateral diffuse opacities were observed as previously on chest radiography, and improved within several days without any specific therapy. The negative C reactive protein level, normal cardiac function and faintly bloody bronchoalveolar lavage fluid were also observed. There was no evidence of aspiration pneumonia, infectious disease, or underlying heart or lung disease. Electroencephalography showed spikes in accord with the left temporal lobe, and the cause of the patient's fainting was thought to be temporal lobe epilepsy. After all other causes had been excluded, this case was diagnosed as neurogenic pulmonary edema associated with epileptic seizure. Only about 40 cases of the postictal pulmonary edema have been reported since 1908, and the pathophysiologic mechanism of this condition is still unknown. Neurogenic pulmonary edema associated with epileptic seizure is rare, but the importance of awareness of this condition needs to be emphasized because it is suspected to be the cause of unexpected sudden death in epileptics. We should consider the disease as important in the differential diagnosis of acute respiratory failure associated with epilepsy.