Improved Antitumor Activity Research Articles

Preclinical Activity of Abemaciclib Alone or in Combination with Antimitotic and Targeted Therapies in Breast Cancer.

The cyclinD:CDK4/6:Rb axis is dysregulated in a variety of human cancers. Targeting this pathway has proven to be a successful therapeutic approach in ER+ breast cancer. In this study, in vitro and in vivo preclinical breast cancer models were used to investigate the expanded use of the CDK4/6 inhibitor, abemaciclib. Using a panel of 44 breast cancer cell lines, differential sensitivity to abemaciclib was observed and was seen predominately in the luminal ER+/HER2- and ER+/HER2+ subtypes. However, a subset of triple-negative breast cancer (TNBC) cell lines with intact Rb signaling were also found to be responsive. Equivalent levels of tumor growth inhibition were observed in ER+/HER2-, ER+/HER2+ as well as biomarker selected TNBC xenografts in response to abemaciclib. In addition, abemaciclib combined with hormonal blockade and/or HER2-targeted therapy induced significantly improved antitumor activity. CDK4/6 inhibition with abemaciclib combined with antimitotic agents, both in vitro and in vivo, did not antagonize the effect of either agent. Finally, we identified a set of Rb/E2F-regulated genes that consistently track with growth inhibitory response and constitute potential pharmacodynamic biomarkers of response to abemaciclib. Taken together, these data represent a comprehensive analysis of the preclinical activity of abemaciclib, used alone or in combination, in human breast cancer models. The subtypes most likely to respond to abemaciclib-based therapies can be identified by measurement of a specific set of biomarkers associated with increased dependency on cyclinD:CDK4/6:Rb signaling. These data support the clinical development of abemaciclib as monotherapy or as a combination partner in selected ER+/HER2-, HER2+/ER+, and TNBCs. Mol Cancer Ther; 17(5); 897-907. ©2018 AACR.

Phase Ib study of concurrent durvalumab and radiation therapy (DUART) followed by adjuvant durvalumab in patients with urothelial cancer of the bladder: BTCRC-GU15-023 study.

455 Background: There is a significant variation in the treatment of locally advanced unresectable (T2-4 N0-2 M0) or cisplatin-ineligible (non-cis) bladder cancer (BC) patients (pts). The advent of immunotherapy (IO) in non-cis stage IV BC has been promising (response rate [RR] 23%; median survival 16 mo) but we are still in need of novel combinations for locally advanced unresectable BC. Durvalumab (Durva) is a human monoclonal antibody that inhibits the binding of PD-L1 to PD-1 on T-cell receptors. It has shown efficacy in platinum refractory BC with RR of 17%. Radiation (RT) is also effective in BC and can upregulate pro-inflammatory signals allowing for improved antitumor activity of IO. We report the safety data from phase Ib trial of combining RT with Durva (DurvaRT) in locally advanced BC. Methods: Treatment (Rx) naïve or post neoadjuvant chemotherapy pts with T3-4, N0-2, M0 who were either unresectable or unfit for surgery were treated with DurvaRT followed by Durva. Rx naïve locally advanced non-cis pts were also included in the study. DurvaRT: Durva 1500mg D1, D28 plus concurrent RT, 64.8Gy given in 36 fractions over 7weeks starting D1. These patients then started adjuvant Q4 weekly Durva after 4 weeks for 12 months. Primary end point for Ph Ib was safety of combining Durva with RT during 7-weeks period. Results: We enrolled 6 pts on phase Ib. 5/6 pts had completed the DurvaRT phase and none of them had any dose limiting toxicity. The table below summarizes the treatment related adverse events (TRAE). Post DurvaRT 3/4 pts have ongoing ORR; 1 pt. had progression; Rx response evaluation in 2 pts is ongoing. Clinical trial information: NCT02891161. Conclusions: DurvaRT was tolerable in pts with locally advanced unresectable BC, where there is a dearth for good Rx options. No grade 3 immune related AEs were observed during DurvaRT. Further investigation with DurvaRT is ongoing to evaluate the efficacy in this subset of pts (Clinical trial # NCT02891161).[Table: see text]

Preclinical Optimization of a CD20-specific Chimeric Antigen Receptor Vector and Culture Conditions.

Chimeric antigen receptor (CAR)-based adoptive T-cell therapy is a highly promising treatment for lymphoid malignancies, and CD20 is an ideal target antigen. We previously developed a lentiviral construct encoding a third generation CD20-targeted CAR but identified several features that required additional optimization before clinical translation. We describe here several improvements, including replacement of the immunogenic murine antigen-binding moiety with a fully human domain, streamlining the transgene insert to enhance lentiviral titers, modifications to the extracellular IgG spacer that abrogate nonspecific activation resulting from binding to Fc receptors, and evaluation of CD28, 4-1BB, or CD28 and 4-1BB costimulatory domains. We also found that restimulation of CAR T cells with an irradiated CD20 cell line boosted cell growth, increased the fraction of CAR-expressing cells, and preserved in vivo function despite leading to a reduced capacity for cytokine secretion in vitro. We also found that cryopreservation of CAR T cells did not affect immunophenotype or in vivo antitumor activity compared with fresh cells. These optimization steps resulted in significant improvement in antitumor activity in mouse models, resulting in eradication of established systemic lymphoma tumors in 75% of mice with a single infusion of CAR T cells, and prolonged in vivo persistence of modified cells. These results provide the basis for clinical testing of a lentiviral construct encoding a fully human CD20-targeted CAR with CD28 and 4-1BB costimulatory domains and truncated CD19 (tCD19) transduction marker.

Highlights of This Issue

In the current landscape of cancer immunotherapy and targeted therapy, it is important to continue to evaluate strategies of improving delivery of chemotherapy while at the same time reducing its classic toxicity profile. In a phase 1 trial, Subbiah and colleagues evaluated a novel cisplatin nanoparticle developed using micellar technology in combination with gemcitabine in patients with advanced solid tumors. In the dose escalation phase, a Bayesian continual reassessment model to determine the optimal dose of NC-6004 was used. A greater cisplatin equivalent dose with no clinically significant neuro-, oto- or nephrotoxicity was achieved. Tolerability and early signals of promising activity was observed with the nanoparticle delivery of cisplatin.Metastatic disease in the central nervous system continues to be a major clinical challenge. CAR-based T-cell immunotherapy is being actively investigated for the treatment of solid tumors, including HER2+ breast cancers. Priceman and colleagues provide preclinical data that demonstrate effective targeting of breast cancer brain metastases with regional intraventricular delivery of T cells engineered with a HER2-CAR containing a 4-1BB intracellular costimulatory domain. The widespread application of this optimized CAR and the novel route of T-cell administration may impact CAR T-cell therapy for other HER2+ solid tumors and their brain metastases.Wang and colleagues reveal that the immunomodulatory drug lenalidomide augments the effectiveness of CAR T cells by several means, including mediating enhanced effector function and improving immune synapse formation between CAR T cells and targets, while maintaining a memory T-cell signature and increasing CAR T-cell persistence. The authors observed significantly improved antitumor activity of adoptively transferred CAR T cells in a multiple myeloma mouse model when this combination therapy was applied. These data suggest a viable strategy to boost the efficacy of CAR T cells against multiple myeloma and provide a generalizable approach for combining lenalidomide and CAR T cells.The use of anti-GD2 mAb as tumor-targeted immunotherapy has improved the outcome for high-risk neuroblastoma patients, but not all patients benefit from this immunotherapy. Prior clinical trials have demonstrated that genotypic polymorphisms specific to NK cells (KIR and KIR-ligand) are associated with clinical outcome. Erbe and colleagues evaluated KIR/KIR-ligand genotypes in patients from a randomized phase-III trial of anti-GD2-based immunotherapy and identified certain KIR/KIR-ligand genotypes that associated with improved outcome if patients received immunotherapy. These results confirm that NK cells mediate outcome in this clinical setting and could provide a biomarker for prospectively personalizing care.

Strain improvement by combined UV mutagenesis and ribosome engineering and subsequent fermentation optimization for enhanced 6'-deoxy-bleomycin Z production.

The bleomycins (BLMs) are important clinical drugs extensively used in combination chemotherapy for the treatment of various cancers. Dose-dependent lung toxicity and the development of drug resistance have restricted their wide applications. 6'-Deoxy-BLM Z, a recently engineered BLM analogue with improved antitumor activity, has the potential to be developed into the next-generation BLM anticancer drug. However, its low titer in the recombinant strain Streptomyces flavoviridis SB9026 has hampered current efforts, which require sufficient compound, to pursue preclinical studies and subsequent clinical development. Here, we report the strain improvement by combined UV mutagenesis and ribosome engineering, as well as the fermentation optimization, for enhanced 6'-deoxy-BLM production. A high producer, named S. flavoviridis G-4F12, was successfully isolated, producing 6'-deoxy-BLM at above 70mg/L under the optimized fermentation conditions, representing a sevenfold increase in comparison with that of the original producer. These findings demonstrated the effectiveness of combined empirical breeding methods in strain improvement and set the stage for sustainable production of 6'-deoxy-BLM via pilot-scale microbial fermentation.

A water-soluble nucleolin aptamer-paclitaxel conjugate for tumor-specific targeting in ovarian cancer

Paclitaxel (PTX) is among the most commonly used first-line drugs for cancer chemotherapy. However, its poor water solubility and indiscriminate distribution in normal tissues remain clinical challenges. Here we design and synthesize a highly water-soluble nucleolin aptamer-paclitaxel conjugate (NucA-PTX) that selectively delivers PTX to the tumor site. By connecting a tumor-targeting nucleolin aptamer (NucA) to the active hydroxyl group at 2′ position of PTX via a cathepsin B sensitive dipeptide bond, NucA-PTX remains stable and inactive in the circulation. NucA facilitates the uptake of the conjugated PTX specifically in tumor cells. Once inside cells, the dipeptide bond linker of NucA-PTX is cleaved by cathepsin B and then the conjugated PTX is released for action. The NucA modification assists the selective accumulation of the conjugated PTX in ovarian tumor tissue rather than normal tissues, and subsequently resulting in notably improved antitumor activity and reduced toxicity.

Tethering of Chemotherapeutic Drug/Imaging Agent to Bile Acid-Phospholipid Increases the Efficacy and Bioavailability with Reduced Hepatotoxicity.

Weakly basic drugs display poor solubility and tend to precipitate in the stomach's acidic environment causing reduced oral bioavailability. Tracing of these orally delivered therapeutic agents using molecular probes is challenged due to their poor absorption in the gastrointestinal tract (GIT). Therefore, we designed a gastric pH stable bile acid derived amphiphile where Tamoxifen (as a model anticancer drug) is conjugated to lithocholic acid derived phospholipid (LCA-Tam-PC). In vitro studies suggested the selective nature of LCA-Tam-PC for cancer cells over normal cells as compared to the parent drug. Fluorescent labeled version of the conjugate (LCA-Tam-NBD-PC) displayed an increased intracellular uptake compared to Tamoxifen. We then investigated the antitumor potential, toxicity, and median survival in 4T1 tumor bearing BALB/c mice upon LCA-Tam-PC treatment. Our studies confirmed a significant reduction in the tumor volume, tumor weight, and reduced hepatotoxicity with a significant increase in median survival on LCA-Tam-PC treatment as compared to the parent drug. Pharmacokinetic and biodistribution studies using LCA-Tam-NBD-PC witnessed the enhanced gut absorption, blood circulation, and tumor site accumulation of phospholipid-drug conjugate leading to improved antitumor activity. Therefore, our studies revealed that conjugation of chemotherapeutic/imaging agents to bile acid phospholipid can provide a new platform for oral delivery and tracing of chemotherapeutic drugs.

Lymphoma Immunochemotherapy: Targeted Delivery of Doxorubicin via a Dual Functional Nanocarrier.

Chemotherapy drug (paclitaxel, PTX) incorporated in a dual functional polymeric nanocarrier, PEG-Fmoc-NLG, has shown promise as an immunochemotherapy in a murine breast cancer model, 4T1.2. The formulation is composed of an amphiphilic polymer with a built-in immunotherapy drug NLG919 that exhibits the immunostimulatory ability through the inhibition of indoleamine 2,3-dioxygenase 1 (IDO-1) in cancer cells. This work evaluates whether the PEG-derivatized NLG polymer can also be used for delivery of doxorubicin (Dox) in treatment of leukemia. The Dox-loaded micelles were self-assembled from PEG-Fmoc-NLG conjugate, which have a spherical shape with a uniform size of ∼120 nm. In cultured murine lymphocytic leukemia cells (A20), Dox-loaded PEG-Fmoc-NLG micelles showed a cytotoxicity that was comparable to that of free Dox. For in vivo studies, significantly improved antitumor activity was observed for the Dox/PEG-Fmoc-NLG group compared to Doxil or the free Dox group in an A20 lymphoma mouse model. Flow cytometric analysis showed that treatment with Dox/PEG-Fmoc-NLG micelles led to significant increases in the numbers of both total CD4+/CD8+ T cells and the functional CD4+/CD8+ T cells with concomitant decreases in the numbers of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Treg). Dox/PEG-Fmoc-NLG may represent a promising immunochemotherapy for lymphoma, which warrants more studies in the future.

378P - Preclinical characterization of IMAB362 for the treatment of gastric carcinoma

Background: Monoclonal antibodies (mAbs) are a key component of cancer therapy. An ideal therapeutic mAb would selectively bind to cancer cells while avoiding binding to healthy tissue. In normal tissue, Claudin 18.2 (CLDN18.2) is expressed in gastric mucosal cell tight junctions, largely inaccessible to mAbs. Upon malignant transformation, perturbations in cell polarity lead to cell surface exposure of CLDN18.2 making it targetable by mAbs. This has driven the development of an anti-CLDN18.2 mAb, IMAB362, which specifically targets CLDN18.2-positive cancer cells while sparing normal tissue. The preclinical characterization of IMAB362 as a targeted therapy for gastric cancer (GC) is presented here. Methods: CLDN18.2 expression was characterized in primary tumors and metastases (32 of which corresponded to primary tumors) from GC patients using a validated, semi-quantitative, IHC assay. IMAB362 binding characteristics and mechanism of action were assessed in vitro using CLDN18.2-expressing cell lines and in vivo in mouse tumor xenografts. Antitumor activity of IMAB362 was assessed in human GC cell line xenografts in mice treated with chemotherapy with/without IMAB362. Results: In patient-derived GC tissue, CLDN18.2 was frequently (∼80%) and robustly expressed in both primary and metastatic tumors. IMAB362 was highly selective for CLDN18.2 both in vivo and in vitro. IMAB362 mediated effective and target-selective antibody-dependent cellular cytotoxicity (ADCC) against GC cell lines with endogenous CLDN18.2 expression and induced complement-dependent cytotoxicity (CDC)-mediated lysis of CLDN18.2-expressing tumor cells. IMAB362-mediated ADCC and CDC were not affected by the presence of CLDN18.2-negative cancer cells. Treatment with chemotherapy sensitized tumor cell lines to IMAB362-mediated mechanisms by increasing CLDN18.2 expression; improved antitumor activity was observed in xenografted mice treated with IMAB362 + chemotherapy compared with mice treated with chemotherapy alone. Conclusions: IMAB362 is a target-selective mAb with strong immune effector mediated antitumor activity (ADCC, CDC) that contributes to the elimination of CLDN18.2-expressing GC cells and synergizes with chemotherapy. Legal entity responsible for the study: Ganymed Pharmaceuticals AG, A company of Astellas Pharma, Inc A company of Astellas Pharma Inc Ganymed Pharmaceuticals GmbH A company of Astellas Pharma Inc Ganymed Pharmaceuticals GmbH A company of Astellas Pharma Inc Ganymed Pharmaceuticals AG, A company of Astellas Pharma Inc Funding: Ganymed Pharmaceuticals AG, A company of Astellas Pharma, Inc A company of Astellas Pharma Inc Ganymed Pharmaceuticals AG, A company of Astellas Pharma, Inc Disclosure: R. Mitnacht-Kraus: Employee of Ganymed Pharmaceuticals AG, a company of Astellas Pharma, Inc. In addition, Dr. Mitnacht-Kraus has a patent P-24PCT issued, a patent P-33PCT issued, a patent P-34PCT issued, and a patent P-36PCT issued. M. Kreuzberg: Employee of Ganymed Pharamceuticals AG, a company of Astellas Pharma, Inc. M. Utsch: Employee of Ganymed Pharmaceuticals AG, a company of Astellas Pharma, Inc. In addition, Dr. Utsch has a patent PCT/EP2012/002210 issued. U. Sahin: Stock option owner, ex-shareholder and cofounder of Ganymed Pharmaceuticals AG and Founder/CEO/shareholder of Biontech Holding outside the submitted work. Dr. Sahin has several patents issued to this work that have been acquired by Astellas. Ö. Türeci: Stock option owner, ex-shareholder, cofounder & CEO of Ganymed Pharmaceuticals AG, has received consultancy fees from Astellas, and has several patents issued to this work that have been acquired by Astellas.

Abstract CT110: Ribociclib in combination with everolimus and exemestane in men and postmenopausal women with HR+/HER2− advanced breast cancer following progression on a CDK4/6 inhibitor: Safety, tolerability, and pharmacokinetic results from Phase 1 of TRINITI-1 study

Abstract Introduction: Preclinical data of improved antitumor activity upon addition of ribociclib to everolimus (EVE) and the interplay of CDK4/6 and the PI3K/mTOR pathway suggest a potential use for combination therapy to restore sensitivity to both CDK4/6 inhibition and endocrine therapy in patients whose disease progresses with CDK4/6 inhibitors. We present Phase 1 data of ribociclib (dosed continuously) + EVE + exemestane (EXE) in patients with endocrine-resistant ABC. Methods: TRINITI-1 is a Phase 1/2, open-label study of ribociclib (250 mg/d or 300 mg/d) + EVE 2.5 mg/d + EXE 25 mg/d in men and postmenopausal women with hormone receptor-positive, HER2− ABC who had progressed on 1 to 3 lines of systemic endocrine therapy, had measurable disease and/or lytic/mixed bone lesions, and had an Eastern Cooperative Oncology Group performance status score of ≤1 (NCT02732119). Progression on a CDK4/6 inhibitor was required only for patients in Phase 2. Patients with visceral crisis, unstable CNS metastases, progression after treatment with >1 CDK4/6 inhibitor, or clinically significant heart disease were excluded. The primary objective of Phase 1 was identification of the maximum tolerated dose (MTD) and/or the recommended Phase 2 dose (RP2D) of ribociclib + EVE + EXE. Secondary objectives included safety, tolerability, and pharmacokinetic analyses. Results: Among the 17 patients evaluated, 0 and 1 (11%) DLTs were noted in the ribociclib 250 mg/d and 300 mg/d cohorts, respectively (Grade 3 febrile neutropenia and Grade 4 neutropenia). Thus, MTD was not reached, and ribociclib 300 mg/d + EVE 2.5 mg/d + EXE 25 mg/d was declared the RP2D. Grade 3/4 drug-related AEs occurred in 75% of patients in each cohort; Grade 3/4 AEs (in >20% of patients) included neutropenia (25% and 50% in 250 mg and 300 mg cohorts, respectively) and decreased neutrophil count (38% and 0%). No increases in liver function tests or QTcF occurred. Median steady-state trough concentrations (Ctrough) of ribociclib at cycle 1, day 15, were 160 ng/mL and 210 ng/mL in the 250 mg/d and 300 mg/d cohorts, respectively, consistent with single-agent ribociclib 280 mg (164 ng/mL). However, median steady-state EVE Ctrough levels when combined with 250 mg and 300 mg ribociclib were within the therapeutic target of 5-15 ng/mL (7.8 ng/mL and 9.4 ng/mL, respectively) and were 2- to 3-fold greater than expected based on single-agent data.Conclusions: Ribociclib at 250 mg/d or 300 mg/d + EVE 2.5 mg/d + EXE 25 mg/d dosed continuously was safe in patients with HER2-, HR+ ABC. Ribociclib 300 mg/d was chosen for the RP2D and is being studied in Phase 2. Ribociclib Ctrough was similar to expected values, whereas EVE Ctrough was 2- to 3-fold greater than expected, resulting in EVE exposure within the therapeutic range despite the low EVE dose. Citation Format: Sara Hurvitz, Denise Yardley, Amelia Zelnak, Angela DeMichele, Elizabeth Tan-Chiu, Cynthia Ma, Tania Small, Chris Tucci, Tanay Samant, Das Purkayastha, Stacy Moulder, Aditya Bardia. Ribociclib in combination with everolimus and exemestane in men and postmenopausal women with HR+/HER2− advanced breast cancer following progression on a CDK4/6 inhibitor: Safety, tolerability, and pharmacokinetic results from Phase 1 of TRINITI-1 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT110. doi:10.1158/1538-7445.AM2017-CT110

Optimizing Therapeutic Effect of Aurora B Inhibition in Acute Myeloid Leukemia with AZD2811 Nanoparticles.

Barasertib (AZD1152), a highly potent and selective aurora kinase B inhibitor, gave promising clinical activity in elderly acute myeloid leukemia (AML) patients. However, clinical utility was limited by the requirement for a 7-day infusion. Here we assessed the potential of a nanoparticle formulation of the selective Aurora kinase B inhibitor AZD2811 (formerly known as AZD1152-hQPA) in preclinical models of AML. When administered to HL-60 tumor xenografts at a single dose between 25 and 98.7 mg/kg, AZD2811 nanoparticle treatment delivered profound inhibition of tumor growth, exceeding the activity of AZD1152. The improved antitumor activity was associated with increased phospho-histone H3 inhibition, polyploidy, and tumor cell apoptosis. Moreover, AZD2811 nanoparticles increased antitumor activity when combined with cytosine arabinoside. By modifying dose of AZD2811 nanoparticle, therapeutic benefit in a range of preclinical models was further optimized. At high-dose, antitumor activity was seen in a range of models including the MOLM-13 disseminated model. At these higher doses, a transient reduction in bone marrow cellularity was observed demonstrating the potential for the formulation to target residual disease in the bone marrow, a key consideration when treating AML. Collectively, these data establish that AZD2811 nanoparticles have activity in preclinical models of AML. Targeting Aurora B kinase with AZD2811 nanoparticles is a novel approach to deliver a cell-cycle inhibitor in AML, and have potential to improve on the clinical activity seen with cell-cycle agents in this disease. Mol Cancer Ther; 16(6); 1031-40. ©2017 AACR.

Phase I study of anti-PD1 in combination with low-dose decitabine in patients with advanced and untreated malignancies.

e14555 Background: Anti-PD1 have produced significant antitumor activity in multiply malignancies, however, resistance to anti-PD1 is becoming increasingly apparent in recent years. Low-dose decitabine, a classical DNA hypomethylating agent, was shown to boost effector T cell function and trigger a T cell-mediated response. This phase I study was designed to assess the safety, immunological effects and antitumor activity of this novel combination in patients with advancedanduntreated lymphomas and solid tumors. Methods: Patients were treated with decitabine (10mg/d on day 1-5) and anti-PD1 (2-3mg/kg, day 8) per 3 weeks. Modified salvage regimens (lymphoma: COP; solid tumors: platinum-based chemotherapy) were allowed to be intermittently inserted for patients with aggressive progression. Treatment continued unless disease progression or severe toxicity. Safety was assessed by CTCAEv4.0, and response by standard international criteria. The phenotype and activity of T cells were periodically measured in peripheral blood by flow cytometry. Results: Todate, 11 patients with heavily treated history and refractory bulky lesions have been enrolled, including 8 with lymphomas (7 NHL, 1 HL resistant to anti-PD1) and 3 with metastatic solid tumors (2 gastric cancers, 1 esophageal cancer) failure to anti-PD1. 5 patients (45%) experienced Grade ≥ 3 toxicities, with 1 taken off due to toxicity, and 1 died of asystole during the term of severe cytokine release syndrome (CRS). The common events of leukocytopenia and CRS were prominent features of anti-PD1 plus decitabine. 9 patients were evaluable for response, 1 HL obtained complete response, 3 NHL and 3 solid tumors achieved partial response, and 2 NHL had stable disease with nearly 20% shrinkage. The frequency of interferon-γ-producing CD8+ T cells in the total CD3+ population was largely increased after anti-PD1 plus decitabine infusion. Conclusions: Decitabine augmented the pro-inflammatory effects of anti-PD1 characterized by systemic inflammation response, and further improved antitumor activity of anti-PD1. Clinical trial information: NCT02961101. Clinical trial information: NCT02961101.

Targeted delivery of epirubicin to tumor-associated macrophages by sialic acid-cholesterol conjugate modified liposomes with improved antitumor activity

With the knowledge that the receptors of sialic acid are overexpressed on the surface of tumor-associated macrophages (TAMs), which play a crucial role in the tumor's progression and metastasis, a sialic acid-cholesterol conjugate (SA-CH) was synthesized and modified on the surface of epirubicin (EPI)-loaded liposomes (EPI-SAL) to improve the delivery of EPI to the TAMs. The liposomes were developed using remote loading technology via a pH gradient. The liposomes were evaluated for particle size, encapsulation efficiency, in vitro release, stability, in vitro cytotoxicity and pharmacokinetics. And the in vitro and in vivo cellular uptake studies demonstrated EPI-SAL achieved enhanced accumulation of EPI into TAMs. The antitumor studies indicated that EPI-SAL provided the strongest antitumor activity compared with the other formulations (EPI-S, EPI-CL and EPI-PL represent EPI solution, conventional liposomal EPI, PEGylated liposomal EPI, respectively), and the survival percent of tumor-bearing mice was 83.3%. The superior antitumor efficacy was probably attributed to the killing of TAMs by EPI-SAL, and modulating the tumor microenvironment with the depletion of TAMs. These findings suggested that SA-CH decorated EPI-loaded liposomes may present an effective strategy to eradicate TAMs, which may be a promising approach for cancer therapy.

Improvement of antitumor activity of doxorubicin by Co-formulation of crocetin and doxorubicin in PLGA nanoparticles

Improvement of antitumor activity of doxorubicin by Co-formulation of crocetin and doxorubicin in PLGA nanoparticles

Improved antitumor activity of TRAIL fusion protein via formation of self-assembling nanoparticle

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been known as a promising agent for cancer therapy due to its specific apoptosis-inducing effect on tumor cells rather than most normal cells. However, systemically delivered TRAIL suffers from a rapid clearance from the body with an extremely short half-life. Thermally responsive elastin-like polypeptides (ELPs) are a promising class of temperature sensitive biopolymers based on the structural motif found in mammalian tropoelastin and retain the advantages of polymeric drug delivery systems. We therefore expressed RGD-TRAIL fused with ELP (RGD-TRAIL-ELP) in E. coli. Purification of RGD-TRAIL-ELP was achieved by the conveniently inverse transition cycling (ITC). The purified RGD-TRAIL-ELP without any chemical conjugation was able to self-assemble into nanoparticle under physiological condition. Non-reducing SDS-PAGE results showed that trimer content of RGD-TRAIL-ELP increased 3.4-fold than RGD-TRAIL. Flow cytometry confirmed that RGD-TRAIL-ELP 3-fold enhanced apoptosis-inducing capacity than RGD-TRAIL. Single intraperitoneal injection of the RGD-TRAIL-ELP nanoparticle induced nearly complete tumor regression in the COLO-205 tumor xenograft model. Histological observation confirmed that RGD-TRAIL-ELP induced significant tumor cell apoptosis without apparent liver toxicity. These findings suggested that a great potential application of the RGD-TRAIL-ELP nanoparticle system as a safe and efficient delivery strategy for cancer therapy.

Design and Synthesis of New 1,3,4-Oxadiazole - Benzothiazole and Hydrazone Derivatives as Promising Chemotherapeutic Agents.

Looking for new cytotoxic and antimicrobial agents with improved antitumor activity, a series of hydrazide and oxadiazole derivatives were designed and synthesized using 3-methoxyphenol as starting substance. Novel N'-(arylidene)-2-(3-methoxyphenoxy)acetohydrazide derivatives (4a-f)/1-(4-substitutedphenyl)-2-[(5-[(3-methoxyphenoxy)methyl]-1,3,4-oxadiazol-2-yl)thio]ethan-1-one derivatives (6a-f)/N-(6-substitutedbenzothiazol-2-yl)-2-[(5-[(3-methoxyphenoxy)methyl]-1,3,4-oxadiazol-2-yl)thio]acetamide derivatives (7a-e) were obtained and evaluated for their in vitro antimicrobial activity against various gram-positive, gram-negative bacteria and fungi. The antimicrobial activity potential of the compounds against gram-negative bacteria was found to have higher compared to the potential against gram-positive bacteria. Also, compounds were screened for their antiproliferative activity against 2 selected human tumor cell lines, A549 lung, MCF7 breast cancer cell line and mouse embryo fibroblast cell line, NIH/3T3 as healthy cell line. Among the compounds evaluated, compound 7c bearing 1,3,4-oxadiazole ring and 6-methoxy benzothiazole moiety exhibited the highest inhibitory activity against A549 and MCF-7 tumor cell lines in contrary to NIH/3T3 cell line, as desired.

Improved antitumor activity and reduced toxicity of doxorubicin encapsulated in poly(ε-caprolactone) nanoparticles in lung and breast cancer treatment: An in vitro and in vivo study

Poly(ε-caprolactone) (PCL) nanoparticles (NPs) offer many possibilities for drug transport because of their good physicochemical properties and biocompatibility. Doxorubicin-loaded PCL NPs have been synthesized to try to reduce the toxicity of doxorubicin (DOX) for healthy tissues and enhance its antitumor effect in two tumor models, breast and lung cancer, which have a high incidence in the global population. PCL NPs were synthesized using a modified nanoprecipitation solvent evaporation method. The in vitro toxicity of PCL NPs was evaluated in breast and lung cancer cell lines from both humans and mice, as was the inhibition of cell proliferation and cell uptake of DOX-loaded PCL NPs compared to free DOX. Breast and lung cancer xenografts were used to study the in vivo antitumor effect of DOX-loaded NPs. Moreover, healthy mice were used for in vivo toxicity studies including weight loss, blood toxicity and tissue damage. The results showed good biocompatibility of PCL NPs in vitro, as well as a significant increase in the cytotoxicity and cell uptake of the drug-loaded in PCL NPs, which induced almost a 98% decrease of the IC50 (E0771 breast cancer cells). Likewise, DOX-loaded PCL NPs led to a greater reduction in tumor volume (≈36%) in studies with C57BL/6 mice compared to free DOX in both lung and breast tumor xenograft models. Nevertheless, no differences were found in terms of mouse weight. Only in the lung cancer model were significant differences in mice survival observed. In addition, DOX-loaded PCL NPs were able to reduce myocardial and blood toxicity in mice compared to free DOX. Our results showed that DOX-loaded PCL NPs were biocompatible, enhanced the antitumor effect of DOX and reduced its toxicity, suggesting that they may have an important potential application in lung and breast cancer treatments.

Abstract P3-04-15: The PI3K-inhibitor, copanlisib, has selective activity in luminal breast cancer cell lines and shows robust combined activity with hormonal blockade and CDK-4/6 inhibition in ER+ breast cancer cell line xenografts

Abstract Background: Genetic and epigenetic alterations in the PI3K/mTOR and cyclin D:CDK-4/6:Rb signaling axes occur frequently in breast cancer and have been attributed to resistance to both ER- and HER2-directed therapeutics. Pharmacologically targeting CDK-4/6 in combination with hormonal blockade provides clinical benefit in patients with advanced ER+ breast cancer. In this study, we evaluated the activity of the pan-class I PI3K inhibitor, copanlisib (BAY-80-6946), with potent alpha and delta activity as a single agent or in combination with CDK-4/6 inhibition and hormonal blockade in a panel of breast cancer cell lines. Methods: The growth inhibitory activity of copanlisib was evaluated against a large panel of 48 breast cancer cell lines molecularly characterized by genomic, transcriptomic and proteomic profiling. IC50 values were determined from direct cell counts using a Z1-particle counter. The activity of copanlisib in combination with hormone blockade and CDK-4/6 inhibition, by palbociclib, was assessed in two cell line xenograft models of ER+ breast cancer; MCF7(PIK3CA-E545K) and ZR751(PIK3CA WT). For xenograft studies, tumor bearing mice were treated once weekly (BID) by intravenous injection with clinically achievable doses of copanlisib (10 mg/kg) as single agent or in combination with tamoxifen or fulvestrant with or without 75 mg/kg daily palbociclib for 21 days. Results: A broad range of IC50 values (0.491-895 nM), with a high degree of separation between sensitive and resistant histologically defined subgroups were determined for copanlisib, indicating the potential for a wide therapeutic window. Luminal subtype, the presence of activating mutations in PIK3CA, high levels of ER, HER2, HER3 and EGFR protein enriched for sensitivity to copanlisib. Activating mutations of KRAS and BRAF were associated with resistance to copanlisib. Single agent copanlisib induced significant tumor growth inhibition (TGI) relative to vehicle control in each of the xenograft models. Modest increases in anti-tumor activity were achieved when copanlisib was combined with hormonal blockade by either tamoxifen or fulvestrant. However, robust tumor regressions were observed with the triple combinations of copanlisib-palbociclib-tamoxifen and copanlisib-palbociclib-fulvestrant. Furthermore, these triple combinations achieved a statistically significant improvement in anti-tumor activity over the standard of care combination of palbociclib plus fulvestrant. Each of the single agent and treatment combinations tested were well tolerated in animals. Discussion: These preclinical data illustrate the potent and selective activity of the pan class I PI3K inhibitor copanlisib in luminal breast cancers and support the clinical investigation of copanlisib in combination with CDK-4/6 inhibition and hormonal blockade in ER+ breast cancer. Citation Format: O'Brien NA, Conklin D, Luo T, Ayala R, Issakhanian S, Kalous O, Von Euw E, Politz O, Wilhelm S, Childs BH, Hurvitz SA, Slamon DJ. The PI3K-inhibitor, copanlisib, has selective activity in luminal breast cancer cell lines and shows robust combined activity with hormonal blockade and CDK-4/6 inhibition in ER+ breast cancer cell line xenografts [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-04-15.

Arginine-Modified Nanostructured Lipid Carriers with Charge-Reversal and pH-Sensitive Membranolytic Properties for Anticancer Drug Delivery.

The ability to escape endo/lysosomal trafficking is critically important to prevent entrapment of nanomedicines in lysosomes and to achieve maximum therapeutic efficacy of drugs delivered to cells through endocytosis. In this study, a novel pH-sensitive chitosan carrier with the ability to reverse its charge during endo/lysosomal trafficking is developed as a way of improving lysosomal disruption. N-Arginine-N-octyl chitosan (AOCS) is synthesized by grafting l-arginine onto carboxymethyl chitosan. The AOCS is used to modify the surface of nanostructured lipid carriers (NLC) to prepare pH-sensitive charge-reversal lysosomolytic nanocarriers (ANLC). The ANLC is loaded with 10-hydroxycamptothecin (HCPT). The results show that ANLC is able to reverse surface zeta potential from negative to positive at lysosomal pH, which contributes to improved release of encapsulated drugs into cytoplasm. The lysosomolytic capability of ANLC is confirmed by confocal microscopy and transmission electron microscopy. In vitro studies demonstrate that the anticancer activity of HCPT-loaded ANLC is improved when compared with HCPT-NLC and free HCPT. In vivo pharmacokinetics and tissue distribution analysis show improved delivery of HCPT-ANLC to subcutaneous Heps mouse liver tumors and greatly improved antitumor activity. The results present ANLC as a promising drug delivery carrier for improved antitumor therapy.

Mirvetuximab Soravtansine (IMGN853), a Folate Receptor Alpha–Targeting Antibody-Drug Conjugate, Potentiates the Activity of Standard of Care Therapeutics in Ovarian Cancer Models

Elevated folate receptor alpha (FRα) expression is characteristic of epithelial ovarian cancer (EOC), thus establishing this receptor as a candidate target for the development of novel therapeutics to treat this disease. Mirvetuximab soravtansine (IMGN853) is an antibody-drug conjugate (ADC) that targets FRα for tumor-directed delivery of the maytansinoid DM4, a potent agent that induces mitotic arrest by suppressing microtubule dynamics. Here, combinations of IMGN853 with approved therapeutics were evaluated in preclinical models of EOC. Combinations of IMGN853 with carboplatin or doxorubicin resulted in synergistic antiproliferative effects in the IGROV-1 ovarian cancer cell line in vitro. IMGN853 potentiated the cytotoxic activity of carboplatin via growth arrest and augmented DNA damage; cell cycle perturbations were also observed in cells treated with the IMGN853/doxorubicin combination. These benefits translated into improved antitumor activity in patient-derived xenograft models in vivo in both the platinum-sensitive (IMGN853/carboplatin) and platinum-resistant (IMGN853/pegylated liposomal doxorubicin) settings. IMGN853 co-treatment also improved the in vivo efficacy of bevacizumab in platinum-resistant EOC models, with combination regimens causing significant regressions and complete responses in the majority of tumor-bearing mice. Histological analysis of OV-90 ovarian xenograft tumors revealed that concurrent administration of IMGN853 and bevacizumab caused rapid disruption of tumor microvasculature and extensive necrosis, underscoring the superior bioactivity profile of the combination regimen. Overall, these demonstrations of combinatorial benefit conferred by the addition of the first FRα-targeting ADC to established therapies provide a compelling framework for the potential application of IMGN853 in the treatment of patients with advanced ovarian cancer.