A first-in-human phase I study of MORAb-004, a monoclonal antibody to endosialin in patients with advanced solid tumors.

PURPOSE: Endosialin (TEM-1, CD248) is a protein expressed on the surface of activated mesenchymal cells, including certain subsets of tumors. Preclinical models suppressing endosialin function have shown antitumor activity. A humanized monoclonal antibody, MORAb-004, was engineered to target endosialin and is the first agent in clinical development for this mesenchymal cell target. EXPERIMENTAL DESIGN: This first-in-human, open-label, phase I study recruited patients with treatment-refractory solid tumors. MORAb-004 was administered intravenously once weekly in 4-week cycles. Objectives included determination of the safety of multiple infusions of MORAb-004, identification of the maximum tolerated dose (MTD), pharmacokinetic modeling, detection of any anti-human antibody response, and assessment of objective radiographic response to therapy. RESULTS: Thirty-six patients were treated at 10 dose levels of MORAb-004, ranging from 0.0625 to 16 mg/kg. Drug-related adverse events were primarily grade 1-2 infusion toxicities. Dose-limiting toxicity of grade 3 vomiting was observed at 16 mg/kg. Eighteen of 32 evaluable patients across all doses achieved disease stability, with minor radiographic responses observed in 4 patients (pancreatic neuroendocrine, hepatocellular, and sarcoma tumor types). Pharmacokinetics showed MORAb-004 accumulation beginning at 4 mg/kg and saturable elimination beginning at 0.25 mg/kg. Exposure increased in a greater-than-dose-proportional manner with terminal half-life increasing proportionally with dose. The MTD was identified as 12 mg/kg. CONCLUSIONS: Preliminary antitumor activity was observed. Safety profile, pharmacokinetics, and early antitumor activity suggest that MORAb-004 is safe at doses up to 12 mg/kg and should be studied further for efficacy.

Adaptive randomized phase II design for biomarker threshold selection and independent evaluation.

BACKGROUND: Frequently a biomarker capable of defining a patient population with enhanced response to an experimental agent is not fully validated with a known threshold at the start of a phase II trial. When such candidate predictive markers are evaluated and/or validated retrospectively, over-accrual of patients less likely to benefit from the regimen may result, leading to underpowered analyses or sub-optimal patient care. PURPOSE: We propose an adaptive randomized phase II study design incorporating prospective biomarker threshold identification (or non-identification), possible early futility stopping, potential mid-trial accrual restriction to marker-positive subjects, and final marker and treatment evaluation in the patient population identified as most likely to benefit. METHODS: An interim analysis is used to determine whether an initially unselected trial should stop early for futility, continue without a promising marker, or adapt accrual and resize (up to a pre-determined maximum) according to a promising biomarker. Final efficacy analyses are performed in the target population identified at the interim as most likely to benefit from the experimental regimen. Simulation studies demonstrate control of false-positive error rates, power, reduced average sample size, and other favorable aspects. RESULTS: The design performs well at identifying a truly predictive biomarker at interim analysis, and subsequently restricting accrual to patients most likely to benefit from the experimental treatment. Type I and type II error rates are adequately controlled by restricting the range of marker prevalence via the candidate thresholds, and by careful consideration of the timing of interim analysis. CONCLUSIONS: In situations where identification and validation of a naturally continuous biomarker are desired within a randomized phase II trial, the design presented herein offers a potential solution.

Adaptive randomized phase II design for biomarker threshold selection and independent evaluation.

BACKGROUND: Frequently a biomarker capable of defining a patient population with enhanced response to an experimental agent is not fully validated with a known threshold at the start of a phase II trial. When such candidate predictive markers are evaluated and/or validated retrospectively, over-accrual of patients less likely to benefit from the regimen may result, leading to underpowered analyses or sub-optimal patient care. PURPOSE: We propose an adaptive randomized phase II study design incorporating prospective biomarker threshold identification (or non-identification), possible early futility stopping, potential mid-trial accrual restriction to marker-positive subjects, and final marker and treatment evaluation in the patient population identified as most likely to benefit. METHODS: An interim analysis is used to determine whether an initially unselected trial should stop early for futility, continue without a promising marker, or adapt accrual and resize (up to a pre-determined maximum) according to a promising biomarker. Final efficacy analyses are performed in the target population identified at the interim as most likely to benefit from the experimental regimen. Simulation studies demonstrate control of false-positive error rates, power, reduced average sample size, and other favorable aspects. RESULTS: The design performs well at identifying a truly predictive biomarker at interim analysis, and subsequently restricting accrual to patients most likely to benefit from the experimental treatment. Type I and type II error rates are adequately controlled by restricting the range of marker prevalence via the candidate thresholds, and by careful consideration of the timing of interim analysis. CONCLUSIONS: In situations where identification and validation of a naturally continuous biomarker are desired within a randomized phase II trial, the design presented herein offers a potential solution.

CD40-activated B cell cancer vaccine improves second clinical remission and survival in privately owned dogs with non-Hodgkin's lymphoma.

Cell-based active immunotherapy for cancer is a promising novel strategy, with the first dendritic cell (DC) vaccine achieving regulatory approval for clinical use last year. Manufacturing remains arduous, especially for DC vaccines, and the prospect of using cell-based immunotherapy in the adjuvant setting or in combination with chemotherapy remains largely untested. Here, we used a comparative oncology approach to test the safety and potential efficacy of tumor RNA-loaded, CD40-activated B cells in privately owned dogs presenting with non-Hodgkin's lymphoma (NHL), a clinical scenario that represents not only a major problem in veterinary medicine but also a bona fide spontaneous animal model for the human condition. When administered to NHL dogs in remission after induction chemotherapy, CD40-B cells electroporated ex vivo with autologous tumor RNA safely stimulated immunity in vivo. Although chemotherapy plus CD40-B vaccination did not improve time-to-progression or lymphoma-specific survival compared to dogs treated with chemotherapy alone, vaccination potentiated the effects of salvage therapy and improved the rate of durable second remissions as well as subsequent lymphoma-specific survival following salvage therapy. Several of these relapsed dogs are now long-term survivors and free of disease for more than a year. Overall, these clinical and immunological results suggest that cell-based CD40 cancer vaccination is safe and synergizes with chemotherapy to improve clinical outcome in canine NHL. More broadly, our findings underscore the unique value of clinical investigations in tumor-bearing companion animals.

Approaches and limitations of phosphatidylinositol-3-kinase pathway activation status as a predictive biomarker in the clinical development of targeted therapy.

The central role played by the class I(A) phosphatidylinositol-3-kinase (PI3K) signaling node in human cancer is highlighted in the multiple mechanisms by which these signals become dysregulated. Many studies suggest that constitutive PI3K activation in human cancer contributes to drug resistance, including targeted agents and standard cytotoxic therapy. The combination of activation mechanisms and the multiple downstream cascades that emanate from the PI3K node contributes to the difficulty in measuring PI3K activation as a biomarker. Although many agents suppress the pathway in models, the challenge remains to translate this biology into a patient selection strategy (i.e., identify patients with "PI3K activated" tumors) and subsequently link this biomarker definition to drug responses in patients. The various genetic and epigenetic lesions resulting in pathway activation necessitate combined approaches using genetic, genomic, and protein biomarkers to accurately characterize "PI3K activated" tumors. Such a combined approach to pathway status can be assessed using a statistical stratification of patients in a randomized trial into "pathway on" and "pathway off" subsets to compare the treatment effect in each arm. Instead of considering individual biomarkers for their predictive ability, this strategy proposes the use of a collection of biomarkers to identify a specific "pathway on" patient population predicted to have clinical benefit from a pathway inhibitor. Here, we review the current understanding of the mechanisms of PI3K activation in breast cancer and discuss a pathway-based approach using PI3K as a predictive biomarker in clinical development, which is currently in use in a global phase 3 setting.

Interferon-gamma-dependent infiltration of human T cells into neuroblastoma tumors in vivo.

PURPOSE: To investigate the impact of interferon-gamma-mediated upregulation of major histocompatibility complex class I expression on tumor-specific T-cell cytotoxicity and T-cell trafficking into neuroblastoma tumors in vivo. EXPERIMENTAL DESIGN: Restoration of major histocompatibility complex class I expression by interferon-gamma treatment enhances killing of neuroblastoma cells. To understand the potential of this approach in vivo, we developed a novel model of neuroblastoma in which NOD/scid/IL2R gamma(null) immunodeficient mice are engrafted with both human T cells and tumor cells. RESULTS: Here, we show enhanced killing of neuroblastoma cells by patient-derived, tumor-specific T cells in vitro. In addition, interferon-gamma treatment in vivo induces efficient upregulation of major histocompatibility complex class I expression on neuroblastoma tumor cells, and this is accompanied by significantly enhanced infiltration of T cells into the tumor. In a pilot clinical trial in patients with high-risk neuroblastoma, we similarly observed augmented T-cell trafficking into neuroblastoma nests in tumor biopsy specimens obtained from patients after 5 days of systemic interferon-gamma therapy. CONCLUSIONS: Interferon-gamma overcomes critical obstacles to the killing of human neuroblastoma cells by specific T cells. Together, these findings provide a rationale for the further testing of interferon-gamma as an approach for improving the efficacy of T cell-based therapies for neuroblastoma and other major histocompatibility complex class I-deficient malignancies. In addition, we describe a model that may expedite the preclinical screening of approaches aimed at augmenting T-cell trafficking into human tumors.

Opportunities posed by novel patient selection biomarker approaches in oncology drug development: going beyond the cytotoxics.

An area of unmet medical need in clinical oncology has been optimizing patient selection for a given therapeutic with the goal of getting the right drug to the right patient. Recent studies have developed preclinical approaches to identifying molecular 'signatures of resistance' for cytotoxic therapies and prospective validation of this strategy is ongoing in the clinic. New challenges in this setting include identifying approaches to patient selection for cytostatic compounds such as signaling pathway inhibitors and stem cell targets. Here, we discuss the biomarker methodologies developed using traditional cytotoxic drugs and how these approaches can be adapted to identify biomarkers of patient selection for novel signaling inhibitors and other novel targets. It has become increasingly clear that such biomarker discovery and validation needs to begin early and continue throughout the drug development process.

Immunosurveillance and survivin-specific T-cell immunity in children with high-risk neuroblastoma.

PURPOSE: Tumor immunosurveillance influences oncogenesis and tumor growth, but it remains controversial whether clinical failure of immunosurveillance is a result of lymphocyte dysfunction or tumor escape. In this study, our goal was to characterize the physiology of tumor immunosurveillance in children with high-risk neuroblastoma (HR-NBL). PATIENTS AND METHODS: Immunohistopathologic studies were carried out on 26 tumor samples from a cohort of HR-NBL patients diagnosed at Children's Hospital of Philadelphia for the 2-year period from May 2003 to May 2005. Blood from nine HLA-A2+ patients in this cohort was analyzed for T cells specific for the antiapoptotic protein survivin. RESULTS: Survivin protein was expressed by 26 of 26 tumors. In HLA-A2+ patients, circulating cytotoxic T lymphocytes (CTLs) specific for survivin were detected by peptide/major histocompatibility complex tetramer analysis in the blood of eight of nine children with HR-NBL at the time of diagnosis. Rather than being selectively rendered anergic in vivo, circulating survivin-specific CTLs were highly functional as shown by cytotoxicity and interferon gamma enzyme-linked immunospot assays in six of nine patients. Survivin-specific CD107a mobilization by T cells was found in five of five patients. By immunohistochemistry, tumor-infiltrating T cells were few or absent in 26 of 26 tumors. CONCLUSION: Children with HR-NBL harbor robust cellular immune responses to the universal tumor antigen survivin at the time of diagnosis, but intratumoral T cells are strikingly rare, suggesting a failure of cellular immunosurveillance. Efforts to develop novel therapies that increase T-cell trafficking into tumor nests are warranted.

Interferon beta adenoviral gene therapy in a patient with ovarian cancer.

Background A 47-year-old woman with a history of ovarian cancer and a 6-year disease-free remission presented with dyspnea and increased abdominal girth. The patient was found to have ascites and a large left pleural effusion, both of which contained malignant cells consistent with recurrent ovarian cancer. Her disease progressed despite treatment with chemotherapeutic and hormonal agents. She was then enrolled in a phase I clinical trial of adenoviral-mediated interferon beta gene therapy. Investigations Abdominal and chest CT scans, 2-[(18)F]fluoro-2-deoxyglucose PET scan, viral cultures, interferon cytokine analysis, immunophenotyping, and tumor cytotoxicity analyses. Diagnosis Stage IV ovarian cancer with malignant ascites and pleural effusion. Management Tunneled pleural catheter and intrapleural adenoviral-mediated interferon beta gene therapy.

RNA-transfected CD40-activated B cells induce functional T-cell responses against viral and tumor antigen targets: implications for pediatric immunotherapy.

Vaccination with antigen-presenting cells (APCs) engineered to mimic mechanisms of immune stimulation represents a promising approach for cancer immunotherapy. Dendritic cell vaccines have entered phase 3 testing in adult malignancies, but such vaccines in children have been limited. We demonstrate that CD40-activated B cells (CD40-B) transfected with RNA may serve as an alternative vaccine that can be generated from small blood volumes regardless of patient age. CD40-B from pediatric patients are efficient APCs and can be loaded with RNA as an antigenic payload, permitting simultaneous targeting of multiple antigenic epitopes without the necessity of HLA matching. For viral and tumor antigens, CD40-B/RNA technology induced cytotoxic T lymphocytes (CTLs) from adults and children, which could be identified with peptide/major histocompatibility complex (MHC) tetramers. These CTLs secreted interferon-gamma (IFN-gamma) and killed targets in an MHC-restricted fashion. For pooled neuroblastoma RNA and autologous neuroblastoma RNA, CTLs that lysed neuroblastoma cell lines, including CTLs specific against the widely expressed tumor-antigen survivin, were generated. These findings support a novel platform for tumor-specific vaccine or adoptive immunotherapies in pediatric malignancies.

Targeting adult and pediatric cancers via cell-based vaccines and the prospect of activated B lymphocytes as a novel modality.

The delivery of cell-based vaccines that exploit natural mechanisms of antigen presentation represents a promising approach for immunotherapy of cancer. This strategy tests the hypothesis that ex vivo manipulation and reinjection of cellular products can induce immune responses and circumvent immune incompetence to achieve clinically significant results. Whole or modified tumor cell vaccines and antigen-loaded dendritic cells (DC) are under intense clinical and scientific evaluation, but other cell-based approaches including the use of activated B lymphocytes have shown promise in preclinical in vitro models. RNA-transfected CD40-activated B cells may fill a particular need in pediatric cancer patients and other patients in whom DC manufacturing is problematic. Thus far, evidence of immunological activity of cell-based vaccines has surpassed that of clinical efficacy, but recent advances and strong safety data from multiple approaches justifies randomized studies in healthier patients who are more likely to benefit.