Functional signaling test identifies HER2 negative breast cancer patients who may benefit from c-Met and pan-HER combination therapy.

BACKGROUND: Research is revealing the complex coordination between cell signaling systems as they adapt to genetic and epigenetic changes. Tools to uncover these highly complex functional linkages will play an important role in advancing more efficacious disease treatments. Current tumor cell signal transduction research is identifying coordination between receptor types, receptor families, and transduction pathways to maintain tumor cell viability despite challenging tumor microenvironment conditions. METHODS: In this report, coactivated abnormal levels of signaling activity for c-Met and HER family receptors in live tumor cells were measured by a new clinical test to identify a subpopulation of breast cancer patients that could be responsive to combined targeted therapies. The CELsignia Multi-Pathway Signaling Function (CELsignia) Test uses an impedance biosensor to quantify an individual patient's ex vivo live tumor cell signaling response in real-time to specific HER family and c-Met co-stimulation and targeted therapies. RESULTS: The test identified breast tumors with hyperactive HER1, HER2, HER3/4, and c-Met coordinated signaling that express otherwise normal amounts of these receptors. The supporting data of the pre-clinical verification of this test included analyses of 79 breast cancer patients' cell response to HER and c-Met agonists. The signaling results were confirmed using clinically approved matching targeted drugs, and combinations of targeted drugs in addition to correlative mouse xenograft tumor response to HER and c-Met targeted therapies. CONCLUSIONS: The results of this study demonstrated the potential benefit of a functional test for identifying a subpopulation of breast cancer patients with coordinated abnormal HER and c-Met signaling for a clinical trial testing combination targeted therapy. Video Abstract.

Addiction to multiple oncogenes can be exploited to prevent the emergence of therapeutic resistance.

Many cancers exhibit sensitivity to the inhibition of a single genetic lesion, a property that has been successfully exploited with oncogene-targeted therapeutics. However, inhibition of single oncogenes often fails to result in sustained tumor regression due to the emergence of therapy-resistant cells. Here, we report that MYC-driven lymphomas frequently acquire activating mutations in ß-catenin, including a previously unreported mutation in a splice acceptor site. Tumors with these genetic lesions are highly dependent on ß-catenin for their survival and the suppression of ß-catenin resulted in marked apoptosis causally related to a decrease in Bcl-xL expression. Using a novel inducible inhibitor of ß-catenin, we illustrate that, although MYC withdrawal or ß-catenin inhibition alone results in initial tumor regression, most tumors ultimately recurred, mimicking the clinical response to single-agent targeted therapy. Importantly, the simultaneous combined inhibition of both MYC and ß-catenin promoted more rapid tumor regression and successfully prevented tumor recurrence. Hence, we demonstrated that MYC-induced tumors are addicted to mutant ß-catenin, and the combined inactivation of MYC and ß-catenin induces sustained tumor regression. Our results provide a proof of principle that targeting multiple oncogene addicted pathways can prevent therapeutic resistance.

RECORD-2: phase II randomized study of everolimus and bevacizumab versus interferon α-2a and bevacizumab as first-line therapy in patients with metastatic renal cell carcinoma.

BACKGROUND: The open-label, phase II RECORD-2 trial compared efficacy and safety of first-line everolimus plus bevacizumab (EVE/BEV) with interferon plus bevacizumab (IFN/BEV) in patients with metastatic renal cell carcinoma. PATIENTS AND METHODS: Previously untreated patients were randomized 1:1 to bevacizumab 10 mg/kg every 2 weeks with either everolimus 10 mg/day (EVE/BEV) or interferon (9 MIU 3 times/week, if tolerated) (IFN/BEV). Tumor assessments occurred every 12 weeks. The primary objective was the assessment of treatment effect on progression-free survival (PFS), based on an estimate of the chance of a subsequent phase III trial success (50% threshold for phase II success). RESULTS: Baseline characteristics were balanced between the EVE/BEV (n = 182) and IFN/BEV (n = 183) arms. The median PFS was 9.3 and 10.0 months in the EVE/BEV and IFN/BEV arms, respectively (P = 0.485). The predicted probability of phase III success was 5.05% (hazard ratio = 0.91; 95% confidence interval 0.69-1.19). The median duration of exposure was 8.5 and 8.3 months for EVE/BEV and IFN/BEV, respectively. The percentage of patients discontinuing because of adverse events (AEs) was 23.4% for EVE/BEV and 26.9% for IFN/BEV. Common grade 3/4 AEs included proteinuria (24.4%), stomatitis (10.6%), and anemia (10.6%) for EVE/BEV and fatigue (17.1%), asthenia (14.4%), and proteinuria (10.5%) for IFN/BEV. The median overall survival was 27.1 months in both arms. CONCLUSIONS: The efficacy of EVE/BEV and IFN/BEV appears similar. No new or unexpected safety findings were identified and, with the exception of proteinuria in about one-fourth of the population, EVE/BEV was generally well tolerated. CLINICAL TRIAL REGISTRY AND TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT00719264.

Challenges and Opportunities in Developing Targeted Therapies for Triple Negative Breast Cancer.

Triple negative breast cancer (TNBC) is a heterogeneous group of breast cancers characterized by their lack of estrogen receptors, progesterone receptors, and the HER2 receptor. They are more aggressive than other breast cancer subtypes, with a higher mean tumor size, higher tumor grade, the worst five-year overall survival, and the highest rates of recurrence and metastasis. Developing targeted therapies for TNBC has been a major challenge due to its heterogeneity, and its treatment still largely relies on surgery, radiation therapy, and chemotherapy. In this review article, we review the efforts in developing targeted therapies for TNBC, discuss insights gained from these efforts, and highlight potential opportunities going forward. Accumulating evidence supports TNBCs as multi-driver cancers, in which multiple oncogenic drivers promote cell proliferation and survival. In such multi-driver cancers, targeted therapies would require drug combinations that simultaneously block multiple oncogenic drivers. A strategy designed to generate mechanism-based combination targeted therapies for TNBC is discussed.

Ongoing complete response after treatment cessation with dabrafenib, trametinib, and cetuximab as third-line treatment in a patient with advanced BRAFV600E mutated, microsatellite-stable colon cancer: A case report and literature review.

Metastatic BRAFV600E mutated colorectal cancer is associated with poor overall survival and modest effectiveness to standard therapies. Furthermore, survival is influenced by the microsatellite status. Patients with microsatellite-stable and BRAFV600E mutated colorectal cancer have the worst prognosis under the wide range of genetic subgroups in colorectal cancer. Herein, we present a patient case of an impressive therapeutic efficacy of dabrafenib, trametinib, and cetuximab as later-line therapy in a 52-year-old woman with advanced BRAFV600E mutated, microsatellite-stable colon cancer. This patient achieved a complete response after 1 year of triple therapy. Due to skin toxicity grade 3 and recurrent urinary tract infections due to mucosal toxicity, a therapy de-escalation to dabrafenib and trametinib was performed, and the double therapy was administered for further 41 months with ongoing complete response. For 1 year, the patient was off therapy and is still in complete remission.

Identification of Lethal Inhibitors and Inhibitor Combinations for Mono-Driver versus Multi-Driver Triple-Negative Breast Cancer Cells.

There are no signaling-based targeted therapies for triple-negative breast cancer. The development of targeted cancer therapy relies on identifying oncogenic signaling drivers, understanding their contributions to oncogenesis and developing inhibitors to block such drivers. In this study, we determine that DU-4475 is a mono-driver cancer cell line relying on BRAF and the mitogen-activated protein kinase pathway for viability and proliferation. It is fully and lethally inhibited by BRAF or Mek inhibitors at low nM concentrations, but it is resistant to inhibitors targeting other signaling pathways. The inhibitory lethality caused by blocking Mek or BRAF is through apoptosis. In contrast, MDA-MB-231 is a multi-driver triple-negative breast cancer cell line dependent on both Src and the KRAS-activated mitogen-activated kinase pathway for proliferation and viability. Blocking each pathway alone only partially inhibits cell proliferation without killing them, but the combination of dasatinib, an Src inhibitor, and trametinib, a Mek inhibitor, achieves synthetic lethality. The combination is highly potent, with an IC50 of 8.2 nM each, and strikingly synergistic, with a combination index of less than 0.003 for 70% inhibition. The synthetic lethality of the drug combination is achieved by apoptosis. These results reveal a crucial difference between mono-driver and multi-driver cancer cells and suggest that pharmacological synthetic lethality may provide a basis for effectively inhibiting multi-driver cancers.

Current Strategies for Treating NSCLC: From Biological Mechanisms to Clinical Treatment.

The identification of specific epidermal growth factor receptor (EGFR)-activating mutations heralded a breakthrough in non-small-cell lung cancer (NSCLC) treatments, with the subsequent development of EGFR-tyrosine kinase inhibitor (TKIs) becoming the first-line therapy for patients harboring EGFR mutations. However, acquired resistance to EGFR-TKIs inevitably occurs in patients following initial TKI treatment, leading to disease progression. Various mechanisms are behind the acquired resistance, and mainly include (1) target gene modification, (2) alternative parallel pathway activation, (3) downstream pathway activation, and (4) histological/phenotypic transformation. Approaches to combat the acquired resistance have been investigated according to these mechanisms. Newer generations of TKIs have been developed to target the secondary/tertiary EGFR mutations in patients with acquired resistance. In addition, combination therapies have been developed as another promising strategy to overcome acquired resistance through the activation of other signaling pathways. Thus, in this review, we summarize the mechanisms for acquired resistance and focus on the potential corresponding therapeutic strategies for acquired resistance.

Biphasic Mathematical Model of Cell-Drug Interaction That Separates Target-Specific and Off-Target Inhibition and Suggests Potent Targeted Drug Combinations for Multi-Driver Colorectal Cancer Cells.

Quantifying the response of cancer cells to a drug, and understanding the mechanistic basis of the response, are the cornerstones for anti-cancer drug discovery. Classical single target-based IC50 measurements are inadequate at describing cancer cell responses to targeted drugs. In this study, based on an analysis of targeted inhibition of colorectal cancer cell lines, we develop a new biphasic mathematical model that accurately describes the cell-drug response. The model describes the drug response using three kinetic parameters: ratio of target-specific inhibition, F1, potency of target-specific inhibition, Kd1, and potency of off-target toxicity, Kd2. Determination of these kinetic parameters also provides a mechanistic basis for predicting effective combination targeted therapy for multi-driver cancer cells. The experiments confirmed that a combination of inhibitors, each blocking a driver pathway and having a distinct target-specific effect, resulted in a potent and synergistic blockade of cell viability, improving potency over mono-agent treatment by one to two orders of magnitude. We further demonstrate that mono-driver cancer cells represent a special scenario in which F1 becomes nearly 100%, and the drug response becomes monophasic. Application of this model to the responses of >400 cell lines to kinase inhibitor dasatinib revealed that the ratio of biphasic versus monophasic responses is about 4:1. This study develops a new mathematical model of quantifying cancer cell response to targeted therapy, and suggests a new framework for developing rational combination targeted therapy for colorectal and other multi-driver cancers.

Application of a Biphasic Mathematical Model of Cancer Cell Drug Response for Formulating Potent and Synergistic Targeted Drug Combinations to Triple Negative Breast Cancer Cells.

Triple negative breast cancer is a collection of heterogeneous breast cancers that are immunohistochemically negative for estrogen receptor, progesterone receptor, and ErbB2 (due to deletion or lack of amplification). No dominant proliferative driver has been identified for this type of cancer, and effective targeted therapy is lacking. In this study, we hypothesized that triple negative breast cancer cells are multi-driver cancer cells, and evaluated a biphasic mathematical model for identifying potent and synergistic drug combinations for multi-driver cancer cells. The responses of two triple negative breast cancer cell lines, MDA-MB-231 and MDA-MB-468, to a panel of targeted therapy drugs were determined over a broad range of concentrations. The analyses of the drug responses by the biphasic mathematical model revealed that both cell lines were indeed dependent on multiple drivers, and inhibitors of individual drivers caused a biphasic response: a target-specific partial inhibition at low nM concentrations, and an off-target toxicity at µM concentrations. We further demonstrated that combinations of drugs, targeting each driver, cause potent, synergistic, and cell-specific cell killing. Immunoblotting analysis of the effects of the individual drugs and drug combinations on the signaling pathways supports the above conclusion. These results support a multi-driver proliferation hypothesis for these triple negative breast cancer cells, and demonstrate the applicability of the biphasic mathematical model for identifying effective and synergistic targeted drug combinations for triple negative breast cancer cells.

Liposomal Irinotecan for Treatment of Colorectal Cancer in a Preclinical Model.

Colorectal cancer (CRC) is the most frequently diagnosed cancer and leading cause of cancer-related deaths worldwide. Because of the use of first-line CRC treatments, such as irinotecan (IRI), is hindered by dose-limiting side effects, improved drug delivery systems may have major clinical benefits for CRC treatment. In this study, we generate and characterize liposomal irinotecan (Lipo-IRI), a lipid-based nanoparticle, which shows excellent bioavailability and pharmacokinetics. Additionally, this formulation allows IRI to be maintained in active form and prolongs its half-life in circulation compared to IRI in solution. Compared with IRI statistically, the level of prostaglandin E2 (PGE2) in colonic tissue decreases, and Bifidobacterium spp. (beneficial intestinal microbiota) content increases in the Lipo-IRI-treated group. Moreover, no damage is observed by the hematoxylin and eosin staining of the normal tissue samples from the Lipo-IRI-treated group. In a xenograft mouse model, CRC tumors shrink markedly following Lipo-IRI treatment, and mice receiving a targeted combination of Lipo-IRI and liposomal doxorubicin (Lipo-Dox) extend their survival rate significantly. Overall, our results demonstrate that this formulation of Lipo-IRI shows a great potential for the treatment of colorectal cancer.

The safety and efficacy of cobimetinib for the treatment of BRAF V600E or V600K melanoma.

INTRODUCTION: In the recent years, melanoma patients' outcome and survival improved, mainly because of systemic treatment improvement with targeted therapy and checkpoint blockade. Targeted therapy with BRAF and MEK inhibitors was approved to treat patients with unresectable or metastatic melanoma, harboring BRAF V600 mutations. This paper addresses the safety and efficacy of cobimetinib, when used in combination with vemurafenib, in the previous mentioned setting. AREAS COVERED: This article presents an overview on the rationale for clinical development of cobimetinib, as well as the mechanism of action, the efficacy and safety, and the most important trials that led to the approval of the combination therapy with vemurafenib. We searched the PubMed for published papers related to safety and efficacy of cobimetinib, and resistance mechanisms to BRAF inhibition. The abstract databases of the American Society of Clinical Oncology and European Society for Medical Oncology were also searched for updates on the mentioned clinical trials. Expert commentary: Patients treated with targeted therapy experience a rapid tumor response. However, virtually all patients will develop resistance to treatment. Therapeutic combinations to overcome resistance mechanisms are currently addressed. In the future, targeted therapy strategy will include three or more drugs, probably from different therapeutic classes.

The NEDD8-activating enzyme inhibitor pevonedistat activates the eIF2α and mTOR pathways inducing UPR-mediated cell death in acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is the leading cause of cancer-related death in children, and cure rates for adults remain dismal. Further, effective treatment strategies for relapsed/refractory ALL remain elusive. We previously uncovered that ALL cells are prone to apoptosis via endoplasmic reticulum (ER) stress/unfolded protein response (UPR)-mediated mechanisms. We investigated the antineoplastic activity of pevonedistat®, a novel NEDD8-activating enzyme inhibitor that targets E3 cullin-RING ligases (CRLs) dependent proteasomal protein degradation, in ALL. Herein, we report that pevonedistat induces apoptosis in ALL cells by dysregulating the translational machinery leading to induction of proteotoxic/ER stress and UPR-mediated cell death. Mechanistically, pevonedistat led to P-eIF2a dephosphorylation causing atypical proteotoxic/ER stress from failure to halt protein translation via the UPR and upregulation of mTOR/p70S6K. Additional studies revealed that pevonedistat re-balanced the homeostasis of pro- and anti-apoptotic proteins to favor cell death through altered expression and/or activity of Mcl-1, NOXA, and BIM, suggesting that pevonedistat has a "priming" effect on ALL by altering the apoptotic threshold through modulation of Mcl-1 activity. Further, we demonstrated that pevonedistat synergizes with selected anti-leukemic agents in vitro, and prolongs survival of NSG mice engrafted with ALL cells, lending support for the use of pevonedistat as part of a multi-agent approach.

A metastatic colon adenocarcinoma harboring BRAF V600E has a durable major response to dabrafenib/trametinib and chemotherapy.

The subset of metastatic colorectal adenocarcinomas that harbor BRAF V600E mutations are aggressive tumors with significantly shortened survival and limited treatment options. Here we present a colorectal cancer patient whose disease progressed through standard chemotherapy and who developed liver metastasis. Comprehensive genomic profiling (FoundationOne(®)) identified a BRAF V600E mutation in the liver lesion, as well as other genomic alterations consistent with colorectal cancers. Combination therapy of dabrafenib and trametinib with standard cytotoxic chemotherapy resulted in a durable major ongoing response for the patient. This report illustrates the utility of comprehensive genomic profiling with personalized targeted therapy for aggressive metastatic colorectal adenocarcinomas.

Mcl-1 downregulation leads to the heightened sensitivity exhibited by BCR-ABL positive ALL to induction of energy and ER-stress.

BCR-ABL positive (+) acute lymphoblastic leukemia (ALL) accounts for ∼30% of cases of ALL. We recently demonstrated that 2-deoxy-d-glucose (2-DG), a dual energy (glycolysis inhibition) and ER-stress (N-linked-glycosylation inhibition) inducer, leads to cell death in ALL via ER-stress/UPR-mediated apoptosis. Among ALL subtypes, BCR-ABL+ ALL cells exhibited the highest sensitivity to 2-DG suggesting BCR-ABL expression may be linked to this increased vulnerability. To confirm the role of BCR-ABL, we constructed a NALM6/BCR-ABL stable cell line and found significant increase in 2-DG-induced apoptosis compared to control. We found that Mcl-1 was downregulated by agents inducing ER-stress and Mcl-1 levels correlated with ALL sensitivity. In addition, we showed that Mcl-1 expression is positively regulated by the MEK/ERK pathway, dependent on BCR-ABL, and further downregulated by combining ER-stressors with TKIs. We determined that energy/ER stressors led to translational repression of Mcl-1 via the AMPK/mTOR and UPR/PERK/eIF2α pathways. Taken together, our data indicate that BCR-ABL+ ALL exhibits heightened sensitivity to induction of energy and ER-stress through inhibition of the MEK/ERK pathway, and translational repression of Mcl-1 expression via AMPK/mTOR and UPR/PERK/eIF2α pathways. This study supports further consideration of strategies combining energy/ER-stress inducers with BCR-ABL TKIs for future clinical translation in BCR-ABL+ ALL patients.