Obexelimab in Systemic Lupus Erythematosus With Exploration of Response Based on Gene Pathway Co-Expression Patterns: A Double-Blind, Randomized, Placebo-Controlled, Phase 2 Trial

OBJECTIVE

Obexelimab is an investigational, bifunctional, noncytolytic monoclonal antibody that binds CD19 and FcyRIIb to inhibit B cells, plasmablasts, and plasma cells. This trial evaluated the efficacy and safety of obexelimab in the treatment of patients with systemic lupus erythematosus (SLE).

METHODS

During screening, patients with active, non-organ-threatening SLE received corticosteroid injections to ameliorate symptoms while immunosuppressants were withdrawn (≤10 mg/day prednisone equivalent and ≤400 mg/day hydroxychloroquine allowed). Patients with improved disease activity were randomized 1:1 to obexelimab 5 mg/kg intravenously or placebo once every 2 weeks until week 32 or loss of improvement (LOI).

RESULTS

In this study, 104 patients were randomized. Analysis of the primary endpoint, proportion of patients reaching week 32 without LOI, used an efficacy-evaluable (EE) population defined as patients who completed the study or withdrew for flare or treatment-related toxicity. This endpoint did not reach statistical significance: 21 of 50 obexelimab-treated patients (42.0%) versus 12 of 42 patients (28.6%) treated with a placebo (P = 0.183). Time to LOI was increased in obexelimab-treated patients versus patients treated with a placebo in the EE (hazard ratio [HR] 0.53, P = 0.025) and intention-to-treat (HR 0.59, P = 0.062) populations. In obexelimab-treated patients, B cells decreased approximately 50%, and trough concentration and inclusion in baseline gene expression clusters with high B cell pathway modules were associated with increased time to LOI. Obexelimab was associated with infusion reactions but was generally safe and well-tolerated.

CONCLUSION

Although the primary endpoint was not reached, secondary analysis showed time to LOI was significantly increased in obexelimab-treated patients, and analysis of patient subsets defined by gene expression patterns at baseline suggests a responding subpopulation.

Pharmacological Activation of STING in Bladder Induces Potent Anti-tumor Immunity in Non-Muscle Invasive Murine Bladder Cancer

Schweinfurthins, a class of natural products, have attracted considerable interest for novel therapy development because of their selective and potent anti-proliferative activity against human cancer cells. However, the underlying mechanism is not well understood. Herein, we demonstrated that schweinfurthins preferentially inhibited the proliferation of PTEN deficient cancer cells by indirect inhibition of AKT phosphorylation. Intracellularly, schweinfurthins and their analogs arrested trans-Golgi-network trafficking, likely by binding to oxysterol-binding proteins, leading to an effective inhibition of mTOR/AKT signaling through inducing endoplasmic reticulum stress and suppressing both lipid raft-mediated PI3K activation and mTOR/RheB complex formation. Moreover, schweinfurthins were found to be highly potent toward PTEN-deficient B cell lymphoma cells, and displayed two orders of magnitude lower activity toward normal human peripheral blood mononuclear cells and primary fibroblasts in vitro. These results revealed a previously unrecognized role of schweinfurthins in trans-Golgi-network trafficking and linked mechanistically this cellular effect with mTOR/AKT signaling and with cancer cell survival and growth. Our findings suggest a new opportunity to modulate oncogenic signaling by interfering with TGN trafficking to treat mTOR/AKT-dependent human cancers.

First-in-human study of the PARP/tankyrase inhibitor E7449 in patients with advanced solid tumours and evaluation of a novel drug-response predictor

Background

This phase 1 study examined the safety, maximum-tolerated dose (MTD) and antitumour activity of E7449, a novel PARP 1/2 and tankyrase 1/2 inhibitor.

Methods

E7449 was orally administered once daily in 28-day cycles to patients with advanced solid tumours (50–800-mg doses). Archival tumour samples from consenting patients were evaluated for the expression of 414 genes in a biomarker panel (2X-121 drug-response predictor [DRP]) found to be predictive of the response to E7449 in cell lines.

Results

Forty-one patients were enrolled (13 pancreatic, 5 ovarian, 4 each with breast, lung or colorectal cancer and 11 with other tumour types). The most common grade ≥3 treatment-related adverse event was fatigue (n = 7, 17.1%). Five patients experienced a dose-limiting toxicity (fatigue, n = 4, 800 mg; anaphylaxis, n = 1, 600 mg) for an MTD of 600 mg. E7449 exhibited antitumour activity in solid tumours, including 2 partial responses (PRs), and stable disease (SD) in 13 patients, which was durable (>23 weeks) for 8 patients. In 13 patients, the 2X-121 DRP identified those achieving PR and durable SD. E7449 showed good tolerability, promising antitumour activity and significant concentration-dependent PARP inhibition following 50–800-mg oral dosing.

Conclusion

The results support further clinical investigation of E7449 and its associated biomarker 2X-121 DRP.

Clinical trial registration

www.ClinicalTrials.gov code: NCT01618136.

Abstract 3269: Discovery and characterization of E7766, a novel macrocycle-bridged STING agonist with pan-genotypic and potent antitumor activity through intravesical and intratumoral administration

Introduction: We report discovery and characterization of E7766, a structurally novel STING agonist, as a potential immunotherapy for solid cancers through intratumoral (IT) administration and for Bacillus Calmette-Guerin (BCG) unresponsive non-muscle invasive bladder cancer (NMIBC) through intravesical (VE) administration.

Methods: E7766 was designed and synthesized to optimize the potency of binding to dimerized STING proteins of different genetic isoforms. The compound was extensively and comparatively characterized in a variety of biochemical, molecular and cellular, in vivo, ex vivo, and primary human tumor and cellular studies for potency, mechanisms and translational biomarkers. Novel preclinical models to mimic orthotopic NMIBC and deep lesion metastasis were developed, and co-crystalization with recombinant proteins of genetic variations was performed.

Results: E7766, a novel Macrocycle-Bridged STING Agonist, showed highly specific and potent agonist activity in both human and mouse STING. In human PBMCs, E7766 demonstrated potent and consistent activity across seven tested human STING genotypes (IC50, 0.15-0.79 μM). By contrast, a reference cyclic dinucleotide STING agonist showed weaker potency and substantial variability across genotypes (IC50, 1.88 μM - >50 μM). Co-crystal structures indicated a structural basis for the superior interactions of E7766 with STING proteins compared with conventional cyclic dinucleotide STING agonists. Intravesical administration of E7766 to a preclinical orthotopic mouse bladder cancer model mimicking the BCG-unresponsive NMIBC demonstrated a dose-dependent and curative activity without serious adverse effects. The anti-tumoral activity was associated with a robust induction of IFNβ, CXCL10 and other downstream effectors of STING pathway inside the bladder cavity. In addition, single IT administration of E7766 to a subcutaneous (SC) tumor in mice bearing dual CT26 tumors in liver and SC lesion cured 90% of animals without recurrence for over 8 months. Those tumor-free animals rejected re-challenge of the same tumor cells in the absence of CD8+ T cells or NK cells, indicating the presence of a highly effective immune memory response following treatment with E7766 independent of either cell population alone.

Conclusions: E7766 is a structurally novel and highly potent STING agonist with pan-genotypic activity, demonstrating curative anti-tumoral activity in murine models of BCG-unresponsive NMIBC and of metastatic tumors in deep lesions. Clinical investigation of E7766 is under discussion.

Citation Format: Kuan-Chun Huang, Atsushi Endo, Shannon McGrath, Dinesh Chandra, Jiayi Wu, Dae-Shik Kim, Diana Albu, Christy Ingersoll, Karen Tendyke, Kara Loiacono, Thomas Noland, David Verbel, Chi Zhang, Ming-Hong Hao, Mark Matijevic, Vaishali Dixit, Renee R. Hukkanen, Janna Hutz, John Wang, Frank Fang, Xingfeng Bao, Donna Kolber-Simonds, Muzaffar Akram, Nadeem Sarwar. Discovery and characterization of E7766, a novel macrocycle-bridged STING agonist with pan-genotypic and potent antitumor activity through intravesical and intratumoral administration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3269.

Evasion of immunosurveillance by genomic alterations of PPARγ/RXRα in bladder cancer

Muscle-invasive bladder cancer (MIBC) is an aggressive disease with limited therapeutic options. Although immunotherapies are approved for MIBC, the majority of patients fail to respond, suggesting existence of complementary immune evasion mechanisms. Here, we report that the PPARγ/RXRα pathway constitutes a tumor-intrinsic mechanism underlying immune evasion in MIBC. Recurrent mutations in RXRα at serine 427 (S427F/Y), through conformational activation of the PPARγ/RXRα heterodimer, and focal amplification/overexpression of PPARγ converge to modulate PPARγ/RXRα-dependent transcription programs. Immune cell-infiltration is controlled by activated PPARγ/RXRα that inhibits expression/secretion of inflammatory cytokines. Clinical data sets and an in vivo tumor model indicate that PPARγ^High/RXRα^S427F/Y impairs CD8⁺ T-cell infiltration and confers partial resistance to immunotherapies. Knockdown of PPARγ or RXRα and pharmacological inhibition of PPARγ significantly increase cytokine expression suggesting therapeutic approaches to reviving immunosurveillance and sensitivity to immunotherapies. Our study reveals a class of tumor cell-intrinsic "immuno-oncogenes" that modulate the immune microenvironment of cancer.Muscle-invasive bladder cancer (MIBC) is a potentially lethal disease. Here the authors characterize diverse genetic alterations in MIBC that convergently lead to constitutive activation of PPARgamma/RXRalpha and result in immunosurveillance escape by inhibiting CD8+ T-cell recruitment.

Exploratory analysis of biomarkers associated with clinical outcomes from the study of lenvatinib in differentiated cancer of the thyroid

BACKGROUND

Lenvatinib significantly prolonged progression-free survival (PFS) versus placebo in the phase III Study of (E7080) LEnvatinib in differentiated Cancer of the Thyroid (SELECT) of patients with radioiodine-refractory differentiated thyroid cancer. This exploratory analysis investigated potential predictive biomarkers of lenvatinib efficacy and target engagement.

PATIENTS AND METHODS

Circulating cytokine/angiogenic factors (CAFs) in blood samples collected at baseline and throughout treatment were analysed from patients randomised to receive lenvatinib or placebo from August 5, 2011 to October 4, 2012. For CAF biomarker analyses, patients were dichotomised by baseline levels. Tumour tissues were analysed for BRAF and NRAS/KRAS/HRAS mutations.

RESULTS

Tumours and CAFs were analysed from 183/392 (47%) and 387/392 (99%) patients, respectively. Lenvatinib PFS benefit was maintained in all assessments. For lenvatinib-treated patients, interaction-term analyses revealed that low baseline Ang2 level was predictive of tumour shrinkage (P_interaction = 0.016) and PFS (P_interaction = 0.018). Vascular endothelial growth factor and fibroblast growth factor 23 (FGF23) were significantly upregulated with lenvatinib, and FGF23 upregulation on cycle 1/day 15 was associated with longer PFS. In mutation analyses, no significant differences in clinical outcomes were observed. BRAF^WT may be a negative prognostic factor for PFS in placebo-treated patients with papillary thyroid cancer (P = 0.019).

CONCLUSION

The lenvatinib PFS benefit was maintained regardless of baseline CAF or BRAF/RAS status. Baseline Ang2 was predictive of PFS in a subgroup of lenvatinib-treated patients, indicating that Ang2 may be predictive of lenvatinib sensitivity. BRAF^WT may be a poor prognostic factor in patients with radioiodine-refractory papillary thyroid cancer. Improved PFS associated with upregulated FGF23 suggests that lenvatinib-induced FGF receptor inhibition contributes to lenvatinib efficacy. Trial registration ID of the main study, SELECT: ClinicalTrials.gov: NCT01321554.

Abstract P5-06-03: Combination of the PARP inhibitor E7449 with eribulin +/- carboplatin in preclinical models of triple negative breast cancer

Introduction: In a small neoadjuvant study in patients with triple negative breast cancer (TNBC) the combination of eribulin plus carboplatin was effective, with a pathologic complete response rate of 43% following 4 cycles of treatment. Significant numbers of sporadic TNBC tumors are deficient in DNA repair capacity and share clinical and pathological features with hereditary BRCA1 mutant disease. PARP inhibitors have demonstrated synthetic lethality in cancer cells with defective DNA repair and have therapeutic potential for TNBC. In this study we describe the combination of PARP inhibitor E7449 with eribulin +/- carboplatin in preclinical models of TNBC.

Methods: E7449, an orally available PARP inhibitor, was administered in combination with eribulin +/- carboplatin to 4 s.c. xenograft models of TNBC: MDA-MB-436 (BRCA1 mutant, PTEN deficient), MDA-MB-468 (BRCA wild type, PTEN deficient), HCC1806 and MDA-MB-231 (BRCA and PTEN wild type).

Results and Discussion: Addition of E7449 to eribulin significantly delayed tumor progression in PTEN deficient MDA-MB-468 xenografts. In the BRCA1 mutant and PTEN deficient MDA-MB-436 xenograft model, combination of E7449 with eribulin enhanced antitumor activity versus eribulin alone. Similar potentiation was observed for carboplatin upon combination with E7449. Treatment of MDA-MB-436 xenografts with the triple combination of E7449 + eribulin + carboplatin was more efficacious than any double combination and was well tolerated at the doses examined. In contrast, no significant combination activity was observed for E7449 plus eribulin in the BRCA and PTEN wild type xenografts HCC1806 and MDA-MB-231, and similarly no potentiation of carboplatin was observed in an MDA-MB-231 xenograft. Notably, combination activity was observed in the BRCA1 mutant (MDA-MB-436) and PTEN deficient (MDA-MB-436 and MDA-MB-468) xenografts and not in the BRCA and PTEN wild-type models (HCC1806 and MDA-MB-231). Data from ongoing studies to evaluate the combination activity of E7449 + eribulin in patient-derived xenograft (PDx) models of TNBC will be presented at the meeting.

Potential biomarkers of sensitivity to the combination are under investigation in both cell line xenograft and PDx models and will be described.

Conclusion: The addition of E7449 to eribulin +/- carboplatin increased antitumor activity in a subset of TNBC models. Biomarker studies aimed at a better understanding of the underlying cause of sensitivity are underway. The preclinical data support assessment of E7449 + eribulin + carboplatin combination therapy in the current phase I/II clinical trial.

Citation Format: Sharon McGonigle, Jiayi Wu, Donna Kolber-Simonds, Natalie C Twine, Jue-lon Shie, Noel Taylor, Sergei Agoulnik, Zoltan Dezso, Shannon McGrath, Mark Matijevic, Shanqin Xu, Galina Kuznetsov, Mary Woodall-Jappe, Kenichi Nomoto. Combination of the PARP inhibitor E7449 with eribulin +/- carboplatin in preclinical models of triple negative breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-06-03.

Lenvatinib treatment of advanced RAI-refractory differentiated thyroid cancer (DTC): Cytokine and angiogenic factor (CAF) profiling in combination with tumor genetic analysis to identify markers associated with response

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Background: Lenvatinib is an oral tyrosine kinase inhibitor targeting VEGFR1-3, FGFR1-4, RET, KIT and PDGFRβ. In a phase II study of lenvatinib, 58 patients (pts) with DTC were enrolled and a response rate of 50% was observed (Sherman, ASCO 2011). Methods: Pts received lenvatinib at a starting dose of 24 mg oral once daily in 28-day cycles. Serum was collected at baseline (BL), on day 8 and on day 36 and concentrations of 47 CAFs were measured using multiplex bead arrays and enzyme-linked immunosorbent assay (ELISA). 33 genes (443 mutations) were examined in archival tumor tissues (n=25). Association of baseline CAF, changes in CAF levels upon treatment and gene mutation status with treatment outcomes was investigated. Results: Combination of low baseline VEGF and ANG-2 (p=0.02 and HR=0.386) correlated with longer PFS. Both baseline and changes in CAF levels demonstrated an association with gene mutation status. High baseline levels of VEGF were observed in pts with wild type RAS and BRAF (p=0.035) whereas high baseline sTIE-2 levels associated with RAS mutation (p=0.023). Supporting pre-clinical mouse xenograft tumor model developed using ANG2-overexpressing human thyroid cancer cell line FTC-286 demonstrated reduced sensitivity to lenvatinib treatment. Increased levels of IL-10 and FGF-2 8-day post-treatment (8d post-tx) significantly associated with RAS (N- or K-) and BRAF mutation. Combination of gene mutation status with baseline CAF levels provided better prediction of longer PFS compared to gene mutation alone. Hierarchical clustering modeling using changes in CAF levels 8d post-tx with tumor shrinkage identified a set of CAFs that could predict two categories of lenvatinib response: longer PFS and greater tumor shrinkage or longer PFS in the absence of significant tumor shrinkage. Conclusions: CAF profiling identified potential predictive biomarkers of lenvatinib treatment outcomes in DTC. Combination of RAS and BRAF mutation with baseline VEGF and ANG-2 or treatment-associated changes in FGF-2 and IL-10 level correlated with lenvatinib treatment response.

Phase I dose-finding study of golvatinib (E7050), a c-Met and Eph receptor targeted multi-kinase inhibitor, administered orally QD to patients with advanced solid tumors

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Background: Golvatinib is a highly potent, small molecule ATP-competitive inhibitor of the c-Met receptor tyrosine kinase and multiple members of the Eph receptor family as well as c-Kit and Ron, based on isolated kinase assays. Golvatinib showed preclinical evidence of anti-tumor activity. This phase 1 study was performed to determine the MTD, safety, PK, PD and preliminary activity of golvatinib. Methods: Patients (pts) with advanced solid tumors, ECOG PS 0-1, ≥ 18 years (yrs) and adequate organ function were eligible. Golvatinib was administered orally, once daily (QD), continuously. Blood samples for PK and PD analysis were collected at multiple time-points. Mandatory tumor biopsies for PD analysis were taken pre and post Cycle 1 in an expanded MTD cohort. Results: 34 pts (M/F: 21/13; median age 63.5yrs [range 32-78]) were treated at 6 dose levels: 100, 200, 270, 360, 450 and 400 mg. Tumor types were colorectal (n=15), lung (n=4), renal (n=4), esophageal (n=2), melanoma (n=2) and others (n=7). Three DLTs were observed: Gr3 GGT and alkaline phosphatase (n=1; 200mg) and repeated Gr2 (n=1) and Gr3 (n=1) fatigue, both at 450mg. The MTD was determined to be 400 mg QD. Frequently occurring adverse events ([AEs]; all grades) were fatigue: 68% (Gr3: 15%), diarrhea: 65%, nausea: 62%, vomiting: 53%, decreased appetite: 47% (Gr3: 9%), ALT increase: 38% and AST increase: 23%. No Gr4 AEs were observed. Best response was stable disease in 6 pts lasting >84 days. PK showed high variability and plasma concentration increased with dose. The Cmax was reached within a median time of 4 hours. Plasma PD analysis showed an increase in soluble c-Met and Ang 2 levels after golvatinib treatment. Tumor PD analysis in 5 pts at 400 mg demonstrated a baseline elevated MET gene copy number, with c-Met overexpression and post treatment decline in phospho(p)-c-Met expression in 1 pt; post-treatment decline in p-c-Met in a 2nd pt, and post-treatment decline in p-ERK in a 3rd pt. Conclusions: Golvatinib at an MTD of 400 mg QD has manageable toxicity. Preliminary PD analysis demonstrated evidence of c-Met target modulation. Further evaluation will continue in phase 2 combination studies.

Immunization with a poly (lactide co-glycolide) encapsulated plasmid DNA expressing antigenic regions of HPV 16 and 18 results in an increase in the precursor frequency of T cells that respond to epitopes from HPV 16, 18, 6 and 11

A phase II trial was conducted in subjects with human papillomavirus (HPV) associated high-grade cervical dysplasia testing the safety and efficacy of a microparticle encapsulated pDNA vaccine. Amolimogene expresses T cell epitopes from E6 and E7 proteins of HPV types 16 and 18. An analysis was performed on a subset of HLA-A2+ subjects to test whether CD8+ T cells specific to HPV 16, 18, 6 and 11 were increased in response to amolimogene immunization. Of the 21 subjects receiving amolimogene, 11 had elevated CD8+ T cell responses to HPV 16 and/or 18 peptides and seven of these also had increases to corresponding HPV 6 and/or 11 peptides. In addition, T cells primed and expanded in vitro with an HPV 18 peptide demonstrated cross-reactivity to the corresponding HPV 11 peptide. These data demonstrate that treatment with amolimogene elicits T cell responses to HPV 16, 18, 6 and 11.

Use of interferon-gamma ELISPOT in monitoring immune responses in humans

The interferon (IFN)-gamma enzyme-linked immunospot (ELISPOT) assay has become a useful tool for immunologists seeking to quantify immune responses on a per-cell basis. The assay is sensitive and allows for the enumeration of low-frequency T-cells. Many have applied this assay to clinical trials as a way to measure biological activity in a patient cohort. It is critical that each laboratory attempting to use the assay in their facility perform rigorous development and qualification work to establish an assay that suits their particular needs. This chapter serves as a demonstration of two practical and slightly different approaches to using the ELISPOT assay to monitor immune activity in the human periphery: (1) assays using whole samples of peripheral blood mononuclear cells with and without the use of additional antigen presenting cells and (2) assays using enriched T-cell populations. Detailed protocols and procedures will be covered, as well as a demonstration of results obtained from three separate applications.

Encapsulated plasmid DNA treatment for human papillomavirus 16-associated anal dysplasia: a Phase I study of ZYC101

High-grade dysplasia induced by high-risk types of human papillomavirus (HPV) precedes invasive cancer in anal squamous epithelium just as it does in the cervix. A therapeutic HPV vaccine strategy as a potential treatment for anal dysplasia was tested in a standard Phase I dose escalation trial. The primary objective was to evaluate the safety of the agent; additional study aims were to evaluate the histological response, immune response, and effect on anal HPV-16 infection. Each subject was treated with four i.m. injections of 50-400 microg of ZYC101 at 3-week intervals. ZYC101 is composed of plasmid DNA encapsulated in biodegradable polymer microparticles. The plasmid DNA encodes for multiple HLA-A2-restricted epitopes derived from the HPV-16 E7 protein, one of two HPV oncoproteins consistently expressed in neoplastic cells. Fifty-six potential anal dysplasia subjects were screened to identify 12 eligible subjects with HPV-16 anal infection and a HLA-A2 haplotype. The investigational agent was well tolerated in all subjects at all dose levels tested. Three subjects experienced partial histological responses, including one of three subjects receiving the 200-microg dose and two subjects at the 400-microg dose level. Using a direct Elispot, 10 of 12 subjects demonstrated increased immune response to the peptide epitopes encoded within ZYC101; each continued to show elevated immune responses 6 months after the initiation of therapy. These results support the continued investigation of a therapeutic vaccination strategy for anal dysplasia.