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Chronic inducible urticaria (CIndU) is characterized by mast cell (MC)-mediated wheals in response to triggers: cold in cold urticaria (ColdU) and friction in symptomatic dermographism (SD). KIT receptor activation by stem cell factor (SCF) is essential for MC function. Barzolvolimab (CDX-0159) is a humanized antibody that inhibits KIT activation by SCF and was well tolerated in healthy volunteers with dose-dependent plasma tryptase suppression indicative of systemic mast cell ablation.This is an open-label, trial in patients with antihistamine refractory ColdU or SD, receiving one IV dose of barzolvolimab (3 mg/kg), with a 12-week follow-up. Primary endpoint was safety/tolerability; pharmacodynamic (PD)/clinical endpoints included serum tryptase, plasma SCF, skin MC histology, provocation tests, urticaria control test (UCT), and dermatology life quality index (DLQI).Analysis populations were safety (n = 21) and pharmacodynamics/clinical activity (n = 20). Barzolvolimab was well tolerated; most adverse events were mild and resolved. Treatment resulted in significant depletion of skin MCs, decreased tryptase (limit of detection), and increased soluble SCF through Week 12. Complete responses (negative provocation test) occurred in 95% (n = 19/20) of patients (n = 10/10 ColdU; n = 9/10 SD), and all (n = 20/20) showed improvement in urticaria control (UCT ≥ 12). The kinetics of clinical activity mirrored that of MC and tryptase reduction. DLQI-measured impairment significantly decreased to minimal/none in 93% of patients on study.In CIndU patients, barzolvolimab was well tolerated, demonstrated marked, rapid, durable depletion of skin MCs, circulating tryptase, and reductions in clinical activity with significant improvements in disease control and quality of life (QoL) demonstrating potential therapeutic effects for MC-mediated disorders.

Supplementary Fig. S1. Heatmap of mRNA expression for individual melanosomal differentiation antigens and a MITF transcriptional signature using a published dataset of melanoma samples (2). Supplementary Fig. S2. GPNMB expression is induced in multiple BRAF-mutant cells in response to MAPK pathway inhibition. Supplementary Fig. S3. Gene expression of MITF and GPNMB in melanoma cells following MAPK pathway inhibition. Supplementary Fig. S4. Dabrafenib and Trametinib stimulate MITF nuclear localization. Supplementary Fig. S5. Correlation of MITF and GPNMB mRNA expression in melanoma samples from patients that were on-treatment or that progressed on therapy with MAPK pathway 7 inhibitors. RT-qPCR data for MITF and GPNMB was expressed as the ratio relative to pretreatment levels. Supplementary Fig. S6. Correlation between the expression of individual melanosomal genes with MITF mRNA expression in melanoma samples from patients that were on-treatment or that progressed on therapy with MAPK pathway inhibitors. RT-qPCR data for each gene and MITF was normalized to GAPDH and expressed as the ratio relative to pre-treatment levels. Supplementary Fig. S7. MAPK pathway inhibition results in elevated levels of soluble GPNMB released from melanoma cells. Table S1: Clinical characteristics of patients biopsied for evaluation of MITF and GPNMB mRNA expression Table S2: Correlation coefficients between individual gene expression and MITF or a MITF Signature Table S3: Complete Responses Following Trametinib Treatment in Cohorts Injected with A375 or WM-2664 Melanoma Cells. Table S4: List of Primers for RT-qPCR Analyses

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Purpose: To determine if BRAF and/or MEK inhibitor–induced GPNMB expression renders melanomas sensitive to CDX-011, an antibody-drug conjugate targeting GPNMB.Experimental Design: The Cancer Genome Atlas melanoma dataset was interrogated for a panel of MITF-regulated melanosomal differentiation antigens, including GPNMB. BRAF-mutant melanoma cell lines treated with BRAF or MEK inhibitors were assessed for GPNMB expression by RT-qPCR, immunoblot, and FACS analyses. Transient siRNA-mediated knockdown approaches were used to determine if MITF is requirement for treatment-induced GPNMB upregulation. GPNMB expression was analyzed in serial biopsies and serum samples from patients with melanoma taken before, during, and after disease progression on MAPK inhibitor treatment. Subcutaneous injections were performed to test the efficacy of MAPK inhibitors alone, CDX-011 alone, or their combination in suppressing melanoma growth.Results: A MITF-dependent melanosomal differentiation signature is associated with poor prognosis in patients with this disease. MITF is increased following BRAF and MEK inhibitor treatment and induces the expression of melanosomal differentiation genes, including GPNMB. GPNMB is expressed at the cell surface in MAPK inhibitor–treated melanoma cells and is also elevated in on-treatment versus pretreatment biopsies from melanoma patients receiving MAPK pathway inhibitors. Combining BRAF and/or MEK inhibitors with CDX-011, an antibody-drug conjugate targeting GPNMB, is effective in causing melanoma regression in preclinical animal models and delays the recurrent melanoma growth observed with MEK or BRAF/MEK inhibitor treatment alone.Conclusions: The combination of MAPK pathway inhibitors with an antibody-drug conjugate targeting GPNMB is an effective therapeutic option for patients with melanoma. Clin Cancer Res; 22(24); 6088–98. ©2016 AACR.

Purpose:ErbB3 and its ligand neuregulin-1 (NRG1) are widely expressed in head and neck squamous cell carcinoma (HNSCC) and associated with tumor progression. A “window-of-opportunity” study (NCT02473731) was conducted to evaluate the pharmacodynamic effects of CDX-3379, an anti-ErbB3 mAb, in patients with HNSCC.Patients and Methods:Twelve patients with newly diagnosed, operable HNSCC received two infusions of CDX-3379 (1,000 mg) at a 2-week interval prior to tumor resection. The primary study objective was to achieve ≥50% reduction in tumor ErbB3 signaling (phosphorylation of ErbB3; pErbB3) in ≥30% of patients. Other potential tumor biomarkers, pharmacokinetics, safety, and tumor measurements were also assessed.Results:pErbB3 was detectable in all tumors prior to treatment and decreased for 10 of 12 (83%) patients following CDX-3379 dosing, with ≥50% reduction in 7 of 12 (58%; P = 0.04; 95% confidence interval, 27.7%–84.8%). Target trough CDX-3379 serum levels were achieved in all patients. CDX-3379 treatment–related toxicity was grade 1–2 and included diarrhea, fatigue, and acneiform dermatitis. Five of 12 (42%) patients had shrinkage in tumor burden, including a marked clinical response in a patient with human papillomavirus–negative oral cavity HNSCC. All patients with tumor shrinkage had tumors that expressed both NRG1 and ErbB3 and demonstrated reduced pErbB3 with CDX-3379 treatment.Conclusions:This study demonstrates that CDX-3379 can inhibit tumor ErbB3 phosphorylation in HNSCC. CDX-3379 was well tolerated and associated with measurable tumor regression. A phase II study (NCT03254927) has been initiated to evaluate CDX-3379 in combination with cetuximab for patients with advanced HNSCC.

Breast cancer; Cancer Càncer de mama; Càncer Cáncer de mama; Cáncer The METRIC study (NCT#0199733) explored a novel antibody–drug conjugate, glembatumumab vedotin (GV), targeting gpNMB that is overexpressed in ~40% of patients with triple-negative breast cancer (TNBC) and associated with poor prognosis. The study was a randomized, open-label, phase 2b study that evaluated progression-free survival (PFS) of GV compared with capecitabine in gpNMB-overexpressing TNBC. Patients who had previously received anthracycline and taxane-based therapy were randomized 2:1 to receive, GV (1.88 mg/kg IV q21 days) or capecitabine (2500 mg/m2 PO daily d1–14 q21 days). The primary endpoint was RECIST 1.1 PFS per independent, blinded central review. In all, 327 patients were randomized to GV (213 treated) or capecitabine (92 treated). Median PFS was 2.9 months for GV vs. 2.8 months for capecitabine. The most common grade ≥3 toxicities for GV were neutropenia, rash, and leukopenia, and for capecitabine were fatigue, diarrhea, and palmar-plantar erythrodysesthesia. The study did not meet the primary endpoint of improved PFS over capecitabine or demonstrate a relative risk/benefit improvement over capecitabine. Funding provided by Celldex Therapeutics, Inc.

Generating responses to tumor antigens poses a challenge for immunotherapy. This phase II trial (NCT02129075) tested fms-like tyrosine kinase 3 (Flt3) ligand pre-treatment enhancement of responses to dendritic cell (DC)-targeting vaccines. We evaluated a regimen of Flt3L (CDX-301) to increase DCs and other antigen-presenting cells, poly-ICLC (TLR3 agonist that activates DCs) and a vaccine comprising anti-DEC-205-NY-ESO-1, a fusion antibody targeting CD205, linked to NY-ESO-1. High-risk melanoma patients were randomized to vaccine, with and without CDX-301. The end point was immune response to NY-ESO-1. Flt3L increased peripheral monocytes and conventional DCs (cDCs), including cross-presenting cDC1 and cDC2 and plasmacytoid DCs. Significant increases in humoral and T-cell responses and activation of DCs, natural killer cells and T cells were elicited. Transcriptional analyses revealed gene signatures associated with CDX-301 induction of an early, durable immune response. This study reveals in vivo effects of Flt3L on innate immune cells in the setting of vaccination, leading to an immunogenic vaccine regimen. Bhardwaj et al. report that adding Flt3 ligand to the treatment strategy effectively increased DC populations and increased T-cell responses in a randomized phase II trial of a DC-targeted vaccine for the melanoma antigen NY-ESO-1.

CD27, a costimulatory molecule on T cells, induces intracellular signals mediating cellular activation, proliferation, effector function, and cell survival on binding to its ligand, CD70. Varlilumab, a novel, first-in-class, agonist immunoglobulin G1 anti-CD27 antibody, mediates antitumor immunity and direct killing of CD27+ tumor cells in animal models. This first-in-human, dose-escalation, and expansion study evaluated varlilumab in patients with hematologic malignancies. Primary objectives were to assess safety and the maximum tolerated and optimal biologic doses of varlilumab. Secondary objectives were to evaluate pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity. In a 3 + 3 dose-escalation design, 30 patients with B-cell (n = 25) or T-cell (n = 5) malignancies received varlilumab (0.1, 0.3, 1, 3, or 10 mg/kg IV) as a single dose with a 28-day observation period, followed by weekly dosing (4 doses per cycle, up to 5 cycles, depending on tumor response). In an expansion cohort, 4 additional patients with Hodgkin lymphoma received varlilumab at 0.3 mg/kg every 3 weeks (4 doses per cycle, up to 5 cycles). No dose-limiting toxicities were observed. Treatment-related adverse events, generally grade 1 to 2, included fatigue, decreased appetite, anemia, diarrhea, and headache. Exposure was linear and dose-proportional across dose groups and resulted in increases in proinflammatory cytokines and soluble CD27. One patient with stage IV Hodgkin lymphoma experienced a complete response and remained in remission at >33 months with no further anticancer therapy. These data support further investigation of varlilumab for hematologic malignancies, particularly in combination approaches targeting nonredundant immune regulating pathways. This trial was registered at www.clinicaltrials.gov as #NCT01460134.

BackgroundThe prognosis is poor for children and adolescents with recurrent osteosarcoma (OS). Glycoprotein non-metastatic B (gpNMB) is a glycoprotein highly expressed in OS cells. We conducted a phase II study of glembatumumab vedotin (GV), a fully human IgG2 monoclonal antibody (CR011) against gpNMB conjugated to the microtubule inhibitor, monomethyl auristatin E.Patients and methodsPatients aged ≥12 years and

Background CDX-1140 is an agonist anti-CD40 mAb selected to optimize systemic exposure and hence tumor microenvironment (TME) ingress. CDX-1140 activity may be enhanced by combining with CDX-301 (recombinant Flt3L), a dendritic cell growth factor, or with pembrolizumab, an anti-PD-1 mAb. Methods Patients with advanced solid or hematologic (Part 1 only) tumors are enrolled. Part 1 dose-escalation results have been presented (SITC 2019). In Part 2, CDX-1140 dose-escalation (0.09–1.5 mg/kg q4w) is in combination with CDX-301 (75 mcg/kg sc QD x 5 for 2 cycles). In Part 3, CDX-1140 dose-escalation (0.72–1.5 mg/kg q3w) is in combination with pembrolizumab 200 mg q3w. Part 1 and 2 expansion cohorts are dosed at the CDX-1140 MTD, 1.5 mg/kg q4w. Part 3 expansion cohorts are planned. Peripheral blood and tumor biomarkers analysis are ongoing. Results 92 patients have been treated (Part 1 n=57, Part 2 n=31, Part 3 n=4). Part 1 expansion cohorts in SCCHN (n=7) and RCC (n=5) are fully enrolled. Part 2 dose-escalation completed to the highest CDX-1140 dose and a SCCHN expansion cohort is ongoing. Part 3 dose-escalation recently initiated. Safety data is available for 23 and 10 patients at the MTD in Part 1 and 2, respectively. In general, the safety profiles were similar, with arthralgia (52% vs. 50%), pyrexia (44% vs 50%), fatigue (30% vs. 50%), chills (39% vs. 40%), vomiting (30% vs. 20%), nausea (26% vs 40%), myalgia (22% vs. 30%), increased ALT (22% vs. 20%), and increased AST (22% vs. 30%) being the most common drug related AEs at the MTD in Part 1 and 2, respectively. Most AEs were low grade. Across all cohorts, cytokine release syndrome (CRS) (G2 n=4, G3 n=2) occurred in 6 (Part 1 n=2; Part 2 n=4) and pneumonitis (G3) occurred in 5 (Part 1 n=4; Part 2 n=1) patients. Immune activation in the TME consistent with CD40 agonism and increases serum inflammatory cytokines were observed. Evidence of anti-tumor activity/clinical benefit include SD (n=13), tumor cavitation (n=2) and a uPR in solid tumors. A patient with follicular lymphoma has an ongoing durable complete metabolic response. Conclusions The CDX-1140 MTD dose of 1.5 mg/kg, a dose level expected to provide good systemic exposure and TME penetration, is generally well tolerated alone and with CDX-301. Transaminitis and CRS have generally been low grade and infrequent. A cohort combining CDX-1140 with chemotherapy will be initiated in patients with previously untreated metastatic pancreatic adenocarcinoma. Trial Registration NCT03329950 Ethics Approval The study was approved by the following: Providence St. Joseph Health IRB, approval number MOD2020001128; WIRB, approval number 1188814 (Hauke, Gabrail, Bordoni & Gordon); University of Pennsylvania IRB, approval number UPCC 18917; Mount Sinai School of Medicine IRB, approval number 18-00202; Memorial Sloan Kettering Cancer Center IRB, approval number 18-225A; Houston Methodist IRB, approval number MOD00000836

CDX-014 is an antibody-drug conjugate directed against TIM-1, a surface marker highly expressed in renal cell carcinoma (RCC) and ovarian carcinoma. This phase I, first-in-human trial was conducted to evaluate the safety and preliminary activity of CDX-014 in patients with advanced refractory RCC, following a dose-escalation and dose expansion design. CDX-014 was administered intravenously at doses ranging from 0.15 to 2.0 mg/kg every 2 or 3 weeks until progression or unacceptable toxicity. Sixteen patients received at least one dose of CDX-014. The maximum tolerated dose was not identified. Most frequent adverse grade 1 or 2 adverse events included nausea (38%), fatigue, alopecia, elevation of AST and decreased appetite (25% each). Adverse events of grade 3 or more included hyperglycemia (19%), urosepsis (6%), and one multi-organ failure (6%) responsible for one treatment-related death. Two patients discontinued therapy for adverse events including fatigue grade 2 and urosepsis grade 4. CDX-014 showed antitumor activity with one prolonged partial response and a clinical benefit rate (objective response or stable disease >6 months) of 31%. The two patients that exhibited the most marked tumor shrinkage had high TIM-1 expression on tumor tissue. Overall, CDX-014 exhibited a manageable toxicity profile and early signs of activity, supporting further evaluation of antibody-drug conjugates in patients with advanced RCC and potentially other TIM-1 expressing cancers. Trial registration https://clinicaltrials.gov/ct2/show/NCT02837991 NCT02837991; July 20, 2016.

High levels of expression of glycoprotein non-metastatic B (gpNMB) in triple negative breast cancer (TNBC) and its association with metastasis and recurrence make it an attractive target for therapy with the antibody drug conjugate, glembatumumab vedotin (CDX-011). This report describes the development of a companion PET-based diagnostic imaging agent using 89Zr-labeled glembatumumab ([89Zr]DFO-CR011) to potentially aid in the selection of patients most likely to respond to targeted treatment with CDX-011. [89Zr]DFO-CR011 was characterized for its pharmacologic properties in TNBC cell lines. Preclinical studies determined that [89Zr]DFO-CR011 binds specifically to gpNMB with high affinity (Kd = 25 ± 5 nM), immunoreactivity of 2.2-fold less than the native CR011, and its cellular uptake correlates with gpNMB expression (r = 0.95). In PET studies at the optimal imaging timepoint of 7 days p.i., the [89Zr]DFO-CR011 tumor uptake in gpNMB-expressing MDA-MB-468 xenografts had a mean SUV of 2.9, while significantly lower in gpNMB-negative MDA-MB-231 tumors with a mean SUV of 1.9. [89Zr]DFO-CR011 was also evaluated in patient-derived xenograft models of TNBC, where tumor uptake in vivo had a positive correlation with total gpNMB protein expression via ELISA (r = 0.79), despite the heterogeneity of gpNMB expression within the same group of PDX mice. Lastly, the radiation dosimetry calculated from biodistribution studies in MDA-MB-468 xenografts determined the effective dose for human use would be 0.54 mSv/MBq. Overall, these studies demonstrate that [89Zr]DFO-CR011 is a potential companion diagnostic imaging agent for CDX-011 which targets gpNMB, an emerging biomarker for TNBC.

2585 Background: CDX-527 is a bispecific antibody (BsAb) targeting PD-L1 and CD27 that is designed to block immune checkpoint PD-L1/PD-1 interactions while providing immune costimulation through CD27 signaling. CD27 is a key immunostimulatory molecule that enhances T cell activation, effector function, and survival. Combining anti-PD-L1 and anti-CD27 mAbs synergize in preclinical studies, activating complementary cytotoxic and proliferative gene expression profiles, respectively. Clinical studies demonstrated the safety and biological activity of combining varlilumab, an agonist anti-CD27 mAb, with nivolumab or atezolizumab, along with modest clinical activity of the combinations. CDX-527 is a novel human BsAb containing a neutralizing, high affinity IgG1k PD-L1 mAb and the single chain Fv fragment (scFv) of an agonist anti-CD27 mAb genetically attached to the C-terminus of each heavy chain, thereby making CDX-527 bivalent for each target. Pre-clinical studies demonstrated enhanced T cell activation by CDX-527 and anti-tumor activity of a surrogate bispecific compared to individual mAb combinations. Methods: CDX527-01 is a phase 1 first-in-human, open-label, multi-center, dose-escalation (DE) and expansion study evaluating safety, pharmacokinetics (PK), pharmacodynamics (PD), and clinical activity of CDX-527 in patient with advanced solid tumors that have progressed on standard-of-care therapy. The primary study objective is to characterize the safety and tolerability of CDX-527. CDX-527 is administered intravenously Q2W with doses ranging from 0.03 mg/kg up to 10.0 mg/kg or until the maximum tolerated dose. The first 2 cohorts of the DE phase initiate with single patients and subsequent DE cohorts will be conducted in 3+3 manner. Tumor-specific expansion cohorts may be enrolled to further characterize the safety, PK, PD, and efficacy of CDX-527. Tumor assessments are performed Q8W by the investigator per iRECIST. Biomarker assessments include characterizing the effects on peripheral blood immune cells and cytokines, and for the expansion cohorts, the impact of CDX-527 on the tumor microenvironment in paired tumor biopsies. Results: To date, 8 patients have received CDX-527 in doses ranging from 0.03 mg/kg to 1 mg/kg and 3 are still on treatment. There has been no drug related SAEs, DLTs or discontinuations due to an AE. Most common treatment related AEs were influenza-like illness, fatigue, and arthralgia (all at 25%). All drug related AEs have been grade 1 or 2. Conclusions: Preliminary results indicate that the novel anti-PD-L1xCD27 bispecific antibody CDX-527 up to and including the 1 mg/kg dose level has been well tolerated. Additional data will be presented, including the safety profile at higher dose levels along with clinical activity, as well as PK and PD data. Clinical trial information: NCT04440943.

Purpose: To determine if BRAF and/or MEK inhibitor–induced GPNMB expression renders melanomas sensitive to CDX-011, an antibody-drug conjugate targeting GPNMB. Experimental Design: The Cancer Genome Atlas melanoma dataset was interrogated for a panel of MITF-regulated melanosomal differentiation antigens, including GPNMB. BRAF-mutant melanoma cell lines treated with BRAF or MEK inhibitors were assessed for GPNMB expression by RT-qPCR, immunoblot, and FACS analyses. Transient siRNA-mediated knockdown approaches were used to determine if MITF is requirement for treatment-induced GPNMB upregulation. GPNMB expression was analyzed in serial biopsies and serum samples from patients with melanoma taken before, during, and after disease progression on MAPK inhibitor treatment. Subcutaneous injections were performed to test the efficacy of MAPK inhibitors alone, CDX-011 alone, or their combination in suppressing melanoma growth. Results: A MITF-dependent melanosomal differentiation signature is associated with poor prognosis in patients with this disease. MITF is increased following BRAF and MEK inhibitor treatment and induces the expression of melanosomal differentiation genes, including GPNMB. GPNMB is expressed at the cell surface in MAPK inhibitor–treated melanoma cells and is also elevated in on-treatment versus pretreatment biopsies from melanoma patients receiving MAPK pathway inhibitors. Combining BRAF and/or MEK inhibitors with CDX-011, an antibody-drug conjugate targeting GPNMB, is effective in causing melanoma regression in preclinical animal models and delays the recurrent melanoma growth observed with MEK or BRAF/MEK inhibitor treatment alone. Conclusions: The combination of MAPK pathway inhibitors with an antibody-drug conjugate targeting GPNMB is an effective therapeutic option for patients with melanoma. Clin Cancer Res; 22(24); 6088–98. ©2016 AACR.

Purpose: ErbB3 and its ligand neuregulin-1 (NRG1) are widely expressed in head and neck squamous cell carcinoma (HNSCC) and associated with tumor progression. A “window-of-opportunity” study (NCT02473731) was conducted to evaluate the pharmacodynamic effects of CDX-3379, an anti-ErbB3 mAb, in patients with HNSCC. Patients and Methods: Twelve patients with newly diagnosed, operable HNSCC received two infusions of CDX-3379 (1,000 mg) at a 2-week interval prior to tumor resection. The primary study objective was to achieve ≥50% reduction in tumor ErbB3 signaling (phosphorylation of ErbB3; pErbB3) in ≥30% of patients. Other potential tumor biomarkers, pharmacokinetics, safety, and tumor measurements were also assessed. Results: pErbB3 was detectable in all tumors prior to treatment and decreased for 10 of 12 (83%) patients following CDX-3379 dosing, with ≥50% reduction in 7 of 12 (58%; P = 0.04; 95% confidence interval, 27.7%–84.8%). Target trough CDX-3379 serum levels were achieved in all patients. CDX-3379 treatment–related toxicity was grade 1–2 and included diarrhea, fatigue, and acneiform dermatitis. Five of 12 (42%) patients had shrinkage in tumor burden, including a marked clinical response in a patient with human papillomavirus–negative oral cavity HNSCC. All patients with tumor shrinkage had tumors that expressed both NRG1 and ErbB3 and demonstrated reduced pErbB3 with CDX-3379 treatment. Conclusions: This study demonstrates that CDX-3379 can inhibit tumor ErbB3 phosphorylation in HNSCC. CDX-3379 was well tolerated and associated with measurable tumor regression. A phase II study (NCT03254927) has been initiated to evaluate CDX-3379 in combination with cetuximab for patients with advanced HNSCC.

Background Glembatumumab vedotin is an antibody-drug conjugate that produced preliminary clinical activity against advanced melanoma in a phase 1 dose-escalation trial. The objective of the current study was to investigate further the antitumor activity of glembatumumab vedotin at the recommended phase 2 dose in heavily pretreated patients with melanoma. Methods This single-arm, phase 2 study enrolled patients with stage IV melanoma who were refractory to checkpoint inhibition and to B-raf proto-oncogene, serine/threonine kinase (BRAF)/mitogen-activated protein kinase kinase (MEK) inhibition (in the presence of a BRAF valine mutation at codon 600). Patients received 1.9 mg/kg glembatumumab vedotin intravenously every 3 weeks until they developed disease progression or intolerance. The primary endpoint was objective response rate (ORR), which was determined according to Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary endpoints included progression-free survival (PFS), duration of response, overall survival (OS), safety, and clinical efficacy versus tumor glycoprotein NMB (gpNMB) expression. Tumor expression of gpNMB was assessed using immunohistochemistry. Results In total, 62 patients received treatment. The ORR was 11% and the median response duration was 6.0 months (95% confidence interval [CI], 4.1 months to not reached). The median PFS was 4.4 months (95% CI, 2.6-5.5 months), and the median OS was 9.0 months (95% CI, 6.1-11.7 months). For patients who developed rash during the first cycle versus those who did not, the ORR was 21% versus 7%, respectively, and there was an overall improvement in PFS (hazard ratio, 0.43; P = .013) and OS (hazard ratio, 0.43; P = .017). The most frequent adverse events were alopecia, neuropathy, rash, fatigue, and neutropenia. With one exception, all evaluable tumors were positive for gpNMB, and 46 of 59 tumors (76%) had 100% gpNMB-positive epithelial cells. Conclusions Glembatumumab vedotin had modest activity and an acceptable safety profile in patients with advanced melanoma who were refractory to checkpoint inhibitors and MEK/BRAF inhibition. Treatment-related rash may be associated with response.

Background Cure rates for children and young adults with osteosarcoma have remained stagnant over the past three decades. Targeting glycoprotein non-metastatic b (GPNMB) with the antibody-drug conjugate glembatumumab vedotin has improved outcomes for patients with melanoma and breast cancer. The potential utility of targeting GPNMB in osteosarcoma was explored. Methods GPNMB protein expression was evaluated by immunohistochemistry in human osteosarcoma tumor samples and by enzyme-linked immunosorbent assay (ELISA) in osteosarcoma cell lines. mRNA expression was measured by quantitative PCR in primary osteosarcoma samples and cell lines. Surface GPNMB expression was evaluated by flow cytometry and correlated with in vitro and in vivo cytotoxicity of glembatumumab vedotin. Results Sixty seven human osteosarcoma samples were evaluated by immunohistochemistry, including 12 samples from initial biopsy, 38 samples from definitive surgery, and 17 from the time of disease recurrence. GPNMB was expressed in 92.5% (62/67) of osteosarcoma samples. All primary osteosarcoma samples expressed high levels of GPNMB mRNA. Glembatumumab induced cytotoxic effects in 74% (14/19) of osteosarcoma cell lines, and GPNMB protein levels correlated with glembatumumab in vitro cytotoxicity (r = −0.46, P = 0.04). All osteosarcoma cell lines demonstrated surface GPNMB expression. Conclusions GPNMB is expressed in osteosarcoma and targeting GPNMB with the antibody-drug conjugate glembatumumab vedotin demonstrates osteosarcoma cytotoxic activity. Clinical trials are indicated to assess the efficacy of targeting GPNMB in patients with osteosarcoma. Pediatr Blood Cancer 2015; 9999:1–7 © 2015 Wiley Periodicals, Inc.

HIV-1 immunotherapy with a combination of first generation monoclonal antibodies was largely ineffective in pre-clinical and clinical settings and was therefore abandoned1–3. However, recently developed single cell based antibody cloning methods have uncovered a new generation of far more potent broadly neutralizing antibodies (bNAbs) to HIV-14,5. These antibodies can prevent infection and suppress viremia in humanized mice (hu-mice) and nonhuman primates, but their potential for human HIV-1 immunotherapy has not been evaluated6–10. Here we report the results of a first-in-man dose escalation phase 1 clinical trial of 3BNC117, a potent human CD4 binding site antibody11, in uninfected and HIV-1-infected individuals. 3BNC117 infusion was well tolerated and demonstrated favorable pharmacokinetics. A single 30 mg/kg infusion of 3BNC117 reduced the viral load (VL) in HIV-1-infected individuals by 0.8 – 2.5 log10 and viremia remained significantly reduced for 28 days. Emergence of resistant viral strains was variable, with some individuals remaining sensitive to 3BNC117 for a period of 28 days. We conclude that as a single agent 3BNC117 is safe and effective in reducing HIV-1 viremia, and that immunotherapy should be explored as a new modality for HIV-1 prevention, therapy, and cure.

Purpose CD27, a costimulatory molecule on T cells, induces intracellular signals that mediate cellular activation, proliferation, effector function, and cell survival upon binding to its ligand, CD70. Varlilumab is a novel, first-in-class, agonist CD27 antibody that stimulates the CD27 pathway, which results in T-cell activation and antitumor activity in tumor models. This first-in-human, dose-escalation and expansion study evaluated the safety, pharmacology, and activity of varlilumab in patients with advanced solid tumors. Methods In a 3 + 3 dose-escalation design (n = 25), patients received a single dose of varlilumab (0.1, 0.3, 1.0, 3.0, or 10 mg/kg intravenously) with a 28-day observation, followed by up to five multidose cycles (one dose per week for 4 weeks), depending on tumor response. Expansion cohorts were initiated at 3.0 mg/kg in patients with melanoma (n = 16) and renal cell carcinoma (RCC; n = 15). Primary objectives were to assess the safety and the maximum tolerated and optimal biologic doses of varlilumab. Secondary objectives were to evaluate the pharmacokinetics, pharmacodynamics, and clinical antitumor activity of varlilumab. Results Exposure to varlilumab was linear and dose proportional across dose groups. Only one patient experienced a dose-limiting toxicity—grade 3 transient asymptomatic hyponatremia at the 1.0-mg/kg dose level. Treatment-related adverse events were generally grade 1 or 2 in severity. Evidence of biologic activity consistent with CD27 stimulation—chemokine induction, T-cell stimulation, regulatory T cell depletion—was observed at all dose levels. A patient with metastatic RCC experienced a partial response (78% shrinkage, progression-free survival > 2.3 years). Eight patients experienced stable disease > 3 months, including a patient with metastatic RCC with progression-free survival of > 3.9 years. Conclusion Dose escalation of varlilumab to 10 mg/kg was well tolerated without identification of a maximum tolerated dose. Varlilumab was biologically and clinically active.

Background Glembatumumab vedotin is an antibody-auristatin conjugate that targets cells expressing the transmembrane glycoprotein NMB (GPNMB, also known as osteoactivin). It has entered clinical evaluation for adult cancers that express GPNMB, including melanoma and breast cancer. Procedures Glembatumumab vedotin was administered intravenously at a dose of 2.5 mg/kg using a weekly × 3 schedule, and its antitumor activity was evaluated against selected Pediatric Preclinical Testing Program (PPTP) solid tumor xenografts using standard PPTP response metrics. Results Among PPTP xenografts, GPNMB was primarily expressed on the osteosarcoma xenografts, all of which expressed GPNMB at the RNA level, although at varying levels. Protein expression assessed by immunohistochemistry (IHC) showed variation across the osteosarcoma xenografts with one model showing no tumor cell expression. Glembatumumab vedotin induced statistically significant differences (P

CDX-1140 is an agonist CD40 mAb intended to promote priming of CD8+ effector T cells through activation of dendritic cells (DC), enhance macrophage tumoricidal activity, and mediate direct killing of CD40-expressing tumor cells. CDX-1140 is a human IgG2 mAb with Fc receptor independent activity and is synergistic with sCD40L, suggesting a potential to enhance CD40L-mediated immune activation. CDX-1140 has a broad dose-dependent activity that may achieve maximal agonist activity at doses that provide significant tumor penetration with minimal toxicities from systemic CD40 activation. CDX-301 (rhFLT3L) is a DC growth factor that markedly increases CD141+ DCs, including in the tumor microenvironment (TME). CD141+ DCs are critical for initiating anti-tumor immune responses and are often depleted within the TME. Preclinical studies have shown that treatment with CDX-301 synergizes with CD40 signaling to enhance anti-tumor immune responses, suggesting that combining CDX-1140 and CDX-301 could result in enhanced clinical benefit. CDX1140-01(NCT03329950) is a Phase I dose-escalation study of CDX-1140 as monotherapy or in combination with CDX-301 evaluating safety, PK, PD, and preliminary clinical activity in patients (pts) with refractory solid tumors and non-Hodgkin lymphoma. CDX-1140 is given iv q 4 weeks at doses from 0.01 to 3 mg/kg utilizing a 3+3 design (first 2 cohorts are single-pts). In combination cohorts (solid tumors only), CDX-301 at 75 μg/kg daily x 5 is administered sc prior to cycles 1 and 2 of escalating doses of CDX-1140 starting at 0.09 mg/kg. Tumor-specific expansion cohorts are planned to further explore the activity of monotherapy or combination treatment. To date, 18 pts across 10 tumor types have been dosed in CDX-1140 monotherapy cohorts with doses ranging from 0.01 to 0.72 mg/kg and without identification of an MTD. There has been one DLT (0.18 mg/kg): grade 3 pneumonitis and hypoxia. One pt (0.72 mg/kg) experienced grade 3 fatigue requiring hospitalization 48 hrs after the first infusion. There have been 3 additional grade 3 treatment-related adverse events: dyspnea (0.18 mg/kg), nausea (0.36 mg/kg), and vomiting (0.36 mg/kg). The first combination cohort (n=5) has been completed. In monotherapy and combination cohorts there have been no significant drug-related changes in liver function tests to date. CDX-1140 PK is quantifiable at doses ≥ 0.09 mg/kg and exposure appears dose proportional. Expected dose-dependent PD effects have shown activation of peripheral blood lymphocytes and increases in pro-inflammatory cytokines and chemokines. Combination with CDX-301 has shown enhanced cytokine responses. The data suggest that CDX-1140 has the expected biologic and safety profile predicted from preclinical studies and may achieve dose levels optimal for systemic exposure. The addition of CDX-301 may enhance the activity of CDX-1140. Citation Format: Rachel E. Sanborn, Nashat Y. Gabrail, Nina Bhardwaj, Michael S. Gordon, Mark O'Hara, Danny Khalil, Thomas Hawthorne, Richard Gedrich, Laura Vitale, Mark Rogalski, Tianshu Li, Tracey Rawls, Tibor Keler, Michael Yellin. First-in-human Phase I study of the CD40 agonist mAb CDX-1140 and in combination with CDX-301 (rhFLT3L) in patients with advanced cancers: Interim results [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 LB-194.

Interruption of combination antiretroviral therapy in HIV-1-infected individuals leads to rapid viral rebound. Here we report the results of a phase IIa open label clinical trial evaluating 3BNC117,a broad and potent neutralizing antibody against the CD4 binding site of the HIV-1 Env protein, during analytical treatment interruption in 13 HIV-1-infected individuals. Participants with 3BNC117-sensitive virus outgrowth cultures were enrolled. Results show that two or four 30 mg kg(-1) 3BNC117 infusions,separated by 3 or 2 weeks, respectively, are generally well tolerated.Infusions are associated with a delay in viral rebound of 5-9 weeks after two infusions, and up to 19 weeks after four infusions, or an average of 6.7 and 9.9 weeks, respectively, compared with 2.6 weeks for historical controls (P < 0.00001). Rebound viruses arise predominantly from a single provirus. In most individuals,emerging viruses show increased resistance, indicating escape.However, 30% of participants remained suppressed until antibody concentrations waned below 20 μg ml(-1), and the viruses emerging in all but one of these individuals showed no apparent resistance to 3BCN117, suggesting failure to escape over a period of 9-19 weeks.We conclude that the administration of 3BNC117 exerts strong selective pressure on HIV-1 emerging from latent reservoirs during analytical treatment interruption in humans.

Background: ErbB3 (HER3) and its ligand, neuregulin-1 (NRG1), are widely expressed in head and neck squamous cell carcinoma (HNSCC) and associated with tumor progression. Preclinically, treatment of primary tumor and cell line tumor models of HNSCC with CDX-3379, an anti-ErbB3 monoclonal antibody, results in significant tumor reduction and reduced tumor ErbB3 signaling (phosphorylation of ErbB3; pErbB3), and antitumor activity is enhanced when combined with cetuximab. In a Phase 1 clinical study, a patient (pt) with cetuximab- refractory HNSCC experienced a durable complete response to CDX-3379 and cetuximab. A “window-of-opportunity” study was conducted to evaluate the effect of CDX-3379 on pErbB3 and other potential tumor biomarkers in pts with HNSCC. Methods: Pts with newly diagnosed, operable HNSCC received CDX-3379 (1000 mg IV) at a 2-week interval prior to tumor resection. Pre- and post-treatment tumor samples were evaluated for expression of pErbB3 (VeraTag®); ErbB3 and NRG (quantitative in situ hybridization); and Ki67 and phosphatase and tensin homolog (PTEN) (quantitative immuno-fluorescence). Primary study objective was to demonstrate ≥ 50% reduction in pErbB3 in ≥ 30% of pts. Toxicity, pharmacokinetics, and tumor measurements were also assessed. Results: 12 pts with HNSCC (5 oral cavity, 4 oropharynx, 3 larynx; 3 HPV+, 9 HPV-; 10 stage IVA) received 2 CDX-3379 doses. Radiographic assessments and tumor resection were performed at a median (range) of 20.5 (15-26) and 27.5 (18-35) days from first CDX-3379 dose. CDX-3379 reduced pErbB3 levels in 10/12 (83%) pt samples, with ≥ 50% decreases in 7/12 (58%, P=0.04). Ki67 decreased in 5/12 (42%). In this small sample, NRG, ErbB3 or PTEN expression did not clearly correlate with changes in pErbB3, Ki67 or tumor measurements. Target trough CDX-3379 serum levels (50 µg/ml based on mouse xenograft models) were achieved in all pts. Treatment-related toxicity included diarrhea (n=6), fatigue (n=2), and acneiform dermatitis (n=2). 11/12 (92%) pts had RECIST stable disease prior to resection. A pt with HPV- HNSCC experienced significant tumor shrinkage (26% decrease in nodal metastasis radiographically; 92% in primary tumor by physical exam) on day 16, as well as marked improvement in pain and ability to eat. Tumor pErbB3 reduced from 0.45 to Conclusions: CDX-3379 is associated with molecular and clinical activity in HNSCC. CDX-3379 administration was well-tolerated and induced a significant decrease in pErbB3. In this small study of 2 CDX-3379 doses over 14 days, one pt experienced a marked clinical effect including reduced tumor size and symptomatology and 92% had RECIST stable disease pre-resection. A Phase 2 study has been initiated to evaluate the combination of CDX-3379 and cetuximab for pts with progressive HNSCC after prior cetuximab and checkpoint inhibition. Citation Format: Umamaheswar Duvvuri, Jonathan George, Seungwon Kim, Diego Alvarado, Veronique Neumeister, Ahmed Chenna, Thomas Hawthorne, Theresa LaVallee, Jennifer R. Grandis, Julie E. Bauman. Molecular and clinical activity of CDX-3379, an anti-ErbB3 monoclonal antibody, in head and neck squamous cell carcinoma: A preoperative "window of opportunity" study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT058.

The Organization for the Harmonisation of Commercial law in Africa (known by its French acronym : OHADA) aims at establishing a unified, secure and modern legal environment with a view to boosting economic activity and investment in its member States. The constitutive treaty states as its main objective the harmonisation of business law in its member States. This aim is to be achieved by means of the development of simple, modern rules in keeping with the state of the economies of the member States. These rules should furthermore be implemented by appropriate judicial procedures, and arbitration as the choice of form of dispute resolution should be promoted. Against this background of OHADA’s efforts at presenting a Uniform Act on contract law, it is necessary to present the hypothesis that to achieve economic development the existence of a strong formal contract law and contract enforcement mechanisms are essential.1 The Nobel laureate Douglass NORTH has held that the inability to develop effective institutions for the enforcement of contracts is the most important cause of historical stagnation and contemporary underdevelopment in the Third World.2

Author(s): Reardon, DA; Schuster, JM; Tran, DD; Fink, KL; Nabors, LB; Li, G; Bota, DA; Lukas, RV; Desjardins, A; Ashby, LS; Duic, JP; Mrugala, MM; Werner, A; Hawthorne, T; He, Y; Green, J; Yellin, MJ; Turner, CD; Davis, TA; Sampson, JH | Abstract: INTRODUCTION: EGFRvIII, a constitutively active EGFR deletion driver mutation, is associated with poor long-term survival in glioblastoma (GB). The investigational vaccine rindopepimut consists of a peptide sequence unique to EGFRvIII conjugated to keyhole limpet hemocyanin (KLH), delivered intradermally with granulocyte macrophage colony-stimulating factor. Three phase II studies in newly diagnosed, resected, EGFRvIII+ GB demonstrated encouraging progression-free survival (PFS), overall survival (OS), and safety profile. Compassionate-use experience suggests that rindopepimut may also provide benefit in relapsed GB, particularly with agents such as bevacizumab (BV). METHODS: In the Phase II "ReACT" study, BV-naive patients in 1st or 2nd relapse with EGFRvIII+ GB were randomly assigned 1:1 to BV plus double-blinded injection of rindopepimut or control (KLH). END POINTS: 6-month PFS (PFS6; primary), objective response rate (ORR), PFS, OS, and safety. RESULTS: Accrual is complete (n = 72); study follow-up continues (n = 30). Primary rindopepimut toxicity is grade 1 to 2 injection site reaction. For rindopepimut + BV vs KLH + BV (per investigator; RANO criteria): PFS6 = 27% (9/33) vs 11% (4/35) (P = .048, 1-side χ test); ORR = 24% (7/29) vs 17% (5/30). Central PFS/ORR assessment is underway. Median (95% CI) OS = 12.0 (9.7, -) vs 8.8 (6.8, 11.4) months (HR = 0.47 [0.25, 0.91]; P = .0208), with 8 vs 4 patients progression-free. OS analyses favor rindopepimut including when adjusted for various prognostic factors. Rindopepimut induced robust anti-EGFRvIII titers (1:12800-1:6553600) in 80% of patients. Rapid titer generation was associated with prolonged OS (HR = 0.47 [0.18, 1.27]; P = .128) within the rindopepimut arm, and was most frequent in patients with KPS ≥ 90 (odds ratio = 9.75; P = .007). Evaluation of humoral response quality and HLA typing vs outcome are underway. In an additional cohort of BV-exposed patients (n = 53), four patients experienced objective tumor response. CONCLUSION: These near-final data show that rindopepimut induces potent EGFRvIII-specific immune response and tumor regression, and appears to significantly prolong survival when administered with BV in patients with relapsed GB.

Cure rates for children and young adults with osteosarcoma have remained stagnant over the past three decades. Targeting glycoprotein non-metastatic b (GPNMB) with the antibody-drug conjugate glembatumumab vedotin has improved outcomes for patients with melanoma and breast cancer. The potential utility of targeting GPNMB in osteosarcoma was explored.GPNMB protein expression was evaluated by immunohistochemistry in human osteosarcoma tumor samples and by enzyme-linked immunosorbent assay (ELISA) in osteosarcoma cell lines. mRNA expression was measured by quantitative PCR in primary osteosarcoma samples and cell lines. Surface GPNMB expression was evaluated by flow cytometry and correlated with in vitro and in vivo cytotoxicity of glembatumumab vedotin.Sixty seven human osteosarcoma samples were evaluated by immunohistochemistry, including 12 samples from initial biopsy, 38 samples from definitive surgery, and 17 from the time of disease recurrence. GPNMB was expressed in 92.5% (62/67) of osteosarcoma samples. All primary osteosarcoma samples expressed high levels of GPNMB mRNA. Glembatumumab induced cytotoxic effects in 74% (14/19) of osteosarcoma cell lines, and GPNMB protein levels correlated with glembatumumab in vitro cytotoxicity (r = -0.46, P = 0.04). All osteosarcoma cell lines demonstrated surface GPNMB expression.GPNMB is expressed in osteosarcoma and targeting GPNMB with the antibody-drug conjugate glembatumumab vedotin demonstrates osteosarcoma cytotoxic activity. Clinical trials are indicated to assess the efficacy of targeting GPNMB in patients with osteosarcoma.

Fms-like tyrosine kinase-3 ligand (Flt3L) uniquely binds the Flt3 (CD135) receptor expressed on hematopoietic stem cells (HSCs), early progenitor cells, immature thymocytes and steady-state dendritic cells (DCs) and induces their proliferation, differentiation, development and mobilization in the bone marrow, peripheral blood and lymphoid organs. CDX-301 has an identical amino-acid sequence and comparable biological activity to the previously tested rhuFlt3L, which ceased clinical development over a decade ago. This Phase 1 trial assessed the safety, pharmacokinetic, pharmacodynamic and immunologic profile of CDX-301, explored alternate dosing regimens and examined the impact of rhuFlt3L on key immune cell subsets. Thirty healthy volunteers received CDX-301 (1-75 μg/kg/day) over 5-10 days. One event of Grade 3 community-acquired pneumonia occurred. There were no other infections, dose-limiting toxicities or serious adverse events. CDX-301 resulted in effective peripheral expansion of monocytes, hematopoietic stem and progenitor cells and key subsets of myeloid DCs and plasmacytoid DCs, with no clear effect on regulatory T cells. These data from healthy volunteers support the potential for CDX-301, as monotherapy or in combination with other agents, in various indications including allogeneic HSC transplantation and immunotherapy, but the effects of CDX-301 will need to be investigated in each of these patient populations.

Purpose Glycoprotein NMB (gpNMB), a negative prognostic marker, is overexpressed in multiple tumor types. Glembatumumab vedotin is a gpNMB-specific monoclonal antibody conjugated to the potent cytotoxin monomethyl auristatin E. This phase II study investigated the activity of glembatumumab vedotin in advanced breast cancer by gpNMB expression. Patients and Methods Patients (n = 124) with refractory breast cancer that expressed gpNMB in ≥ 5% of epithelial or stromal cells by central immunohistochemistry were stratified by gpNMB expression (tumor, low stromal intensity, high stromal intensity) and were randomly assigned 2:1 to glembatumumab vedotin (n = 83) or investigator's choice (IC) chemotherapy (n = 41). The study was powered to detect overall objective response rate (ORR) in the glembatumumab vedotin arm between 10% (null) and 22.5% (alternative hypothesis) with preplanned investigation of activity by gpNMB distribution and/or intensity (Stratum 1 to Stratum 3). Results Glembatumumab vedotin was well tolerated as compared with IC chemotherapy (less hematologic toxicity; more rash, pruritus, neuropathy, and alopecia). ORR was 6% (five of 83) for glembatumumab vedotin versus 7% (three of 41) for IC, without significant intertreatment differences for predefined strata. Secondary end point revealed ORR of 12% (10 of 83) versus 12% (five of 41) overall, and 30% (seven of 23) versus 9% (one of 11) for gpNMB overexpression (≥ 25% of tumor cells). Unplanned analysis showed ORR of 18% (five of 28) versus 0% (0 of 11) in patients with triple-negative breast cancer (TNBC), and 40% (four of 10) versus 0% (zero of six) in gpNMB-overexpressing TNBC. Conclusion Glembatumumab vedotin is well tolerated in heavily pretreated patients with breast cancer. Although the primary end point in advanced gpNMB-expressing breast cancer was not met for all enrolled patients (median tumor gpNMB expression, 5%), activity may be enhanced in patients with gpNMB-overexpressing tumors and/or TNBC. A pivotal phase II trial (METRIC [Metastatic Triple-Negative Breast Cancer]) is underway.

BACKGROUND: EGFRvIII, a constitutively active tumorigenic EGFR deletion mutation, is linked to poor long-term survival. The investigational vaccine rindopepimut consists of the unique EGFRvIII peptide sequence conjugated to keyhole limpet hemocyanin (KLH), delivered intradermally with GM-CSF. Three phase II studies of rindopepimut in newly diagnosed, resected, EGFRvIII+ glioblastoma have shown encouraging PFS and OS. Bevacizumab (BV), an agent with activity in glioblastoma, may augment EGFRvIII-specific immune response and antitumor activity through inhibition of VEGF and its immunosuppressive properties. METHODS: “ReACT” is a Phase II study of rindopepimut plus BV in patients with 1st or 2nd relapse of EGFRvIII+ glioblastoma. BV-naive pts (Group 1; n = 70) are randomized 1:1 to BV plus double-blinded injection of either rindopepimut or control (KLH). BV-refractory patients (progression within 2 months of BV; Group 2/2C, n = 98) receive BV plus open-label rindopepimut. RESULTS: 234/700 (33%) screened patients are EGFRvIII+. 115 patients (Group 1 = 72, Group 2/2C = 43) are enrolled. Primary toxicity is Grade 1-2 injection site reaction. In group 1, for rindopepimut + BV vs. KLH + BV, objective response rate (ORR; investigator-assessed, RANO criteria) is 23% (6/26) vs 12% (3/25) [35% vs. 20% including responses observed at a single time point (“unconfirmed”)]. In Group 2/2C (evaluable n = 30), one unconfirmed PR and one sustained PR (patient continues treatment at 15 months) occurred. Two additional patients had pre-study progression >2 months after BV; one maintained a CR for 11.1 months (peak anti-EGFRvIII titer = 1:3,276,800), while the second experienced an unconfirmed CR. Median peak rindopepimut-induced anti-EGFRvIII humoral response is 1:25,600 [range

Purpose The antibody-drug conjugate glembatumumab vedotin links a fully human immunoglobulin G2 monoclonal antibody against the melanoma-related glycoprotein NMB (gpNMB) to the potent cytotoxin monomethyl auristatin E. This study evaluated the safety and activity of glembatumumab vedotin in patients with advanced melanoma. Patients and Methods Patients received glembatumumab vedotin every 3 weeks (schedule 1) in a dose escalation and phase II expansion at the maximum-tolerated dose (MTD). Dosing during 2 of 3 weeks (schedule 2) and weekly (schedule 3) was also assessed. The primary end points were safety and pharmacokinetics. The secondary end points included antitumor activity, gpNMB expression, and immunogenicity. Results One hundred seventeen patients were treated using schedule 1 (n = 79), schedule 2 (n = 15), or schedule 3 (n = 23). The MTDs were 1.88, 1.5, and 1.0 mg/kg for schedules 1, 2, and 3, respectively. Grade 3/4 treatment-related toxicities that occurred in two or more patients included rash, neutropenia, fatigue, neuropathy, arthralgia, myalgia, and diarrhea. Three treatment-related deaths (resulting from pneumococcal sepsis, toxic epidermal necrolysis, and renal failure) occurred at doses exceeding the MTDs. In the schedule 1 phase II expansion cohort (n = 34), five patients (15%) had a partial response and eight patients (24%) had stable disease for ≥ 6 months. The objective response rate (ORR) was 2 of 6 (33%) for the schedule 2 MTD and 3 of 12 (25%) for the schedule 3 MTD. Rash was correlated with a greater ORR and improved progression-free survival. Conclusion Glembatumumab vedotin is active in advanced melanoma. The schedule 1 MTD (1.88 mg/kg once every 3 weeks) was associated with a promising ORR and was generally well tolerated. More frequent dosing was potentially associated with a greater ORR but increased toxicity.

The thermodynamic parameters of interactions between six variants of the anti-idiotypic monoclonal antibody (mAb) CGP 60686 produced by the hybridoma MK2-23 with an idiotypic mAb and five different anti-anti-idiotypic mAb were studied with high sensitivity titration calorimetry. CGP 60686 recognizes an epitope in the antigen-combining region of the human high-molecular-weight-melanoma-associated antigen (HMW-MAA)-specific mouse mAb CGP 76873 produced by the hybridoma 763.74. The five HMW-MAA-specific anti-anti-idiotypic mAbs GH 464, GH 518, GH 149, GH 386 and GH 586 were generated from mice immunization with mAb CGP 60686. All interactions between the anti-idiotypic mAb and the idiotypic mAb or the anti-anti-idiotypic mAb showed large exothermic binding enthalpies between -15 and -23 kcal/mol and binding affinities larger than 6 x 10(9) M-1. Four of the five anti-anti-idiotypic mAbs tested exhibited significantly higher binding enthalpies for the interaction with the anti-idiotypic than the idiotypic mAbs. Replacement of either the heavy or the light chain variable region of the anti-idiotypic mAbs with an unrelated variable region abolished the idiotype to anti-idiotype interaction. Thus, both the heavy and the light chain variable region of the anti-idiotypic mAbs are required for binding to the idiotype. The values of the binding enthalpy showed only small variations when binding of the idiotypic mAb CGP 76873 to four variants of the anti-idiotypic mAb CGP 60686 with different immunoglobulin constant regions, but identical variable regions were compared. Furthermore, Fab fragments of the idiotypic mAbs showed almost the same binding enthalpy per binding site as the whole IgG molecules. Immunoglobulin constant regions thus had little influence on the idiotype to anti-idiotype interactions. Taken together, the observed thermodynamic parameters suggest that the idiotype to anti-idiotype interactions studied here are enthalpy-driven processes with only minor entropic contributions. High sensitivity titration calorimetry was used to monitor protein-protein interactions within an anti-idiotypic antibody cascade. It was found that the direct measurement of the interaction enthalpy allowed a quantitative characterization of the binding processes studied.

Glycoprotein non-metastatic melanoma B (GPNMB) is a transmembrane protein overexpressed in 30 - 40% of triple negative breast cancer (TNBC) and has shown to be associated with metastasis and disease recurrence. An anti-GPNMB antibody drug conjugate, Glembatumumab Vedotin (CDX-011), is currently in Phase II clinical trials for the treatment of metastatic TNBC patients, with promising outcomes. Positron Emission Tomography using radiolabeled antibodies could be advantageous in stratifying patients who may benefit from CDX-011, tracking the biodistribution of CDX-011, and assessing GPNMB expression in vivo. To this end, we radiolabeled the naked antibody, Glembatumumab (CR011), with the positron-emitting 89Zr (half life = 3.3 days). We characterized the stability, affinity, rate of cellular internalization, and specificity of 89Zr-CR011 using various cell-binding assays in human TNBC cell lines. We determined that 89Zr-CR011 is stable in serum solution for up to 5 days, binds specifically to GPNMB+ TNBC cells with high affinity (KD = 16 nM), and internalizes rapidly (50% within 30 - 60 min). We conducted a biodistribution study from 1 - 12 days post administration via tail vein in GPNMB+ MDA-MB-468 xenografts to determine the time point at which we achieve the optimal tumor-to-nontarget ratios. A subset of mice was administered a blocking dose of unlabeled CR011 (100-fold excess, 1 mg/mouse), where we observed a 2.5-fold reduction in 89Zr-CR011 tumor uptake, confirming the specificity of 89Zr-CR011 for GPNMB+ TNBC tumors. PET imaging studies and dosimetry calculations are currently in progress. This preliminary study demonstrates that 89Zr-CR011 may be an excellent companion diagnostic agent for CDX-011 therapy and an essential tool to assess the function of GPNMB in vivo. Citation Format: Bernadette V. Marquez, Supum Lee, Tibor Keler, Thomas Hawthorne, Jeremy Hoog, Shunqiang Li, Cynthia Ma, Suzanne E. Lapi. Targeting GPNMB with 89Zr-CR011 for PET imaging of triple negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4209.

Background: The duration of survival benefit from MAPKi in B-raf mutant melanoma (MEL) is limited by the near universal development of resistance (RES). Recently, MiTF, a transcription factor and master regulator of melanocyte differentiation - was identified as a hub of MAPKi RES. Given its dual role as both a tumor promoter and inducer of MEL senescence, MiTF is a problematic therapeutic target. Pigmentation is a MiTF-dependent feature of MELs correlates with poor survival. We have interrogated the MAPKi/MiTF-dependent regulation of a panel of MITF-regulated melanosomal differentiation antigens (MDAs) for their potential as therapeutic targets to overcome MAPKi RES. Methods: The TCGA MEL gene expression data set was interrogated. B-raf mutant MEL cells were exposed to dabrafenib (D), or trametinib (T). qRT-PCR, Immunoblot or FACS were used to assess MiTF and MDA expression. Serial biopsy tissue and serum samples from MEL patients taken before treatment, during treatment, and at progression with MAPKi therapy were obtained, and analyzed by IHC and qRT-PCR, RNAseq, and ELISA. Transient siRNA-mediated knockdown was used to assess the requirement for MiTF, in MAPKi-mediated induction of MDAs, including GPNMB. To assess the interaction between MAPKi and CDX011 (C), a GPNMB- targeted antibody drug conjugate, mice bearing A375 and WM2664 xenografts were treated with T or DT + C in combination. Results: MiTF is strongly correlated with MDAs, including GPNMB in gene-expression datasets derived from human MEL tumors. A MiTF driven MDA-gene-signature correlates with poor survival among 291 melanoma patients. MAPKi treatment increased MiTF and MDAs in MEL cells, and induced pigmentation in vivo. This phenotype was reversible as MEL acquired RES to MAPKi. Knockdown of MiTF leads to abrogation of MAPKi-mediated GPNMB induction. GPNMB promotes MEL invasion in vitro. MiTF and MDA were elevated in tumors and serum from patients receiving MAPKi treatment and returned to baseline in tumors that acquired RES. The addition of C to either T or DT led to, decreased pigmentation, prolonged tumor regression and inhibited the development RES to T or DT treatment in vivo. Tumors that acquired RES to DT displayed increased c-Met expression and MAPK activation; tumors treated with DT+C failed to develop this phenotype. Conclusions: MAPKi induce MDA in a MiTF-dependent manner in MEL. This process leads to melanocytic differentiation and increased pigmentation, which is subsequently reversed as a tumor acquires RES to MAPKi. This demonstrates the plasticity of MEL in response to MAPKi. The pigmented phenotype is less proliferative but more invasive which is in part mediated by GPNMB. This transient phenotype may allow tumors to acquire characteristics (ie. c-Met upregulation and MAPK re-activation) which contribute to MAPKi RES. Targeting a pro-invasive MDA, GPNMB with CDX-011 subverts this plasticity and impairs the development of MAPKi RES. Citation Format: April A.N. Rose, Matthew G. Annis, Dennie T. Frederick, Zhifeng Dong, Lawrence Kwong, Tibor Keller, Thomas Hawthorne, Ian R. Watson, Keith T. Flaherty, Peter M. Siegel. Targeting the melanosome: overcoming MAPK-inhibitor resistance in melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 296.

Nature 522, 487–491 (2015); doi:10.1038/nature14411 In this Letter, the grant U19AI111825-01 Cooperative Centers on Human Immunology from NIH was erroneously included in the Acknowledgments section; this has been corrected in the online versions of the paper.

2009 Background: EGFRvIII, a constitutively active EGFR deletion driver mutation, is associated with poor long-term survival in glioblastoma (GB). The investigational vaccine rindopepimut consists ...

3024 Background: CD27, a member of the TNF receptor superfamily, is a co-stimulatory molecule that regulates T cell activation, survival, and memory responses through interaction with a tightly regulated ligand, CD70. CDX-1127 is an anti-CD27 human antibody shown to activate human T cells when combined with T cell receptor stimulation, and mediate anti-tumor activity in human CD27 transgenic mice challenged with syngeneic tumors. Methods: In a 3+3 dose-escalation (DE), patients (pts) with advanced B-cell lymphoma received CDX-1127 (0.1, 0.3, 1.0, 3.0 or 10 mg/kg IV) as a single dose with 28-day observation, followed by up to 5 treatment cycles (4 weekly doses / Day 85 restaging), until progression. Results: 19 pts (3 Hodgkin (HL), 5 follicular, 9 diffuse large B-cell, 2 unspecified non-Hodgkin) have received CDX-1127. DE has exceeded 3 mg/kg with no DLT; enrollment at 10 mg/kg is ongoing. Treatment-related toxicity, generally Grade 1-2, included fatigue, nausea, decreased appetite and anemia. A pt with St...

3027 Background: CD27 is a co-stimulatory molecule that regulates T cell activation, survival, and memory responses through interaction with a tightly regulated ligand, CD70. CDX-1127 is an anti-CD...

Introduction: Glembatumumab vedotin is an antibody-auristatin conjugate that targets cells expressing the transmembrane glycoprotein NMB (GPNMB, also known as osteoactivin, dc-HIL, and HGFIN). Because of the restrictive expression of GPNMB, testing was limited to the PPTP osteosarcoma (OS) xenograft panel as well as two non-GPNMB expressing rhabdomyosarcoma (RMS) xenografts. Methods: Glembatumumab vedotin was administered intravenously in 0.9% saline at a dose of 2.5 mg/kg using a weekly x 3 schedule. GPNMB was assessed at the RNA level (Agilent SurePrint3) and by IHC. Results: All of the six OS xenografts against which glembatumumab vedotin was tested expressed GPNMB at the RNA level as evaluated using Agilent gene expression arrays. By contrast, none of the RMS xenografts expressed GPNMB at the RNA level. Most OS xenografts showed GPNMB expression detectable by IHC (6/7), while none of the RMS xenografts showed tumor staining for GPNMB (0/6). Glembatumumab vedotin was well tolerated, and all 8 tested xenograft models were considered evaluable for efficacy. For the OS xenografts, glembatumumab vedotin induced significant differences in EFS distribution compared to control in each of the 6 models studied. Three of 6 OS xenografts showed maintained complete responses (MCR) to glembatumumab vedotin. Two other xenografts showed progressive disease with growth delay (PD2), with one of these showing near stable disease during the 6 weeks of treatment and observation. The final OS xenograft showed progressive disease with no growth delay (PD1). As expected, the two RMS xenografts showed limited responses to glembatumumab vedotin (PD1 and PD2), although one did show significant tumor growth inhibition with an EFS T/C value of 2.6. Two of the OS xenografts with MCR showed the highest GPNMB expression at the RNA level. Conversely, the xenograft with the lowest GPNMB gene expression had the poorest response to glembatumumab vedotin. For GPNMB protein expression assessed by IHC, 2 of the xenografts with MCR showed the highest expression level and highest percent tumor expression, but the other responding line showed GPNMB expression on only 5% of tumor cells, despite exhibiting one of the highest expression levels of GPNMB by mRNA. The two OS xenograft lines least responsive to glembatumumab vedotin were also the least responsive OS xenografts to vincristine and eribulin. Conclusions: Glembatumumab vedotin showed high-level activity against 3 of 6 OS xenografts. Response of OS xenografts to glembatumumab vedotin may be related to both GPNMB expression and to the intrinsic susceptibility of xenografts to tubulin inhibitors. RMS xenografts showed PD1 or PD2 responses to glembatumumab vedotin despite having known sensitivity to tubulin-binding agents such as eribulin. Glembatumumab vedotin is the first antibody-drug conjugate with documented in vivo activity against OS. (Supported by NO1-CM-42216) Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C207. Citation Format: Richard Gorlick, Anders Kolb, Jainrong Wu, Raushan Kurmasheva, Thomas Hawthorne, Peter Houghton, Malcolm Smith. Pediatric Preclinical Testing Program (PPTP) stage 1 evaluation of Glembatumumab Vedotin. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C207.

9063 Background: CR011-vcMMAE, an ADC of fully-human monoclonal anti-GPNMB antibody (Ab) with monomethylauristatin E (MMAE), is in Ph I/II trials in pts with melanoma and breast cancer. We report PK and toxicity data from a Ph I study in melanoma pts treated every (q) 3 weeks (w), qw, or 2 of 3w. Methods: Enzyme-linked immunosorbent assays were used to measure ADC, total Ab (TA), soluble GPNMB (sGPNMB), and anti-ADC Ab in pt samples. Free MMAE was measured by liquid chromatography/mass spectrometry. Results: Initially, 32 pts were treated in 9 cohorts of 0.03 to 2.63 mg/kg iv q3w using standard 3+3 dose escalation. Noncompartmental PK analysis showed dose-proportional TA, ADC and free MMAE levels. As previously reported, maximum tolerated dose (MTD) was 1.88 mg/kg iv q3w; dose limiting toxicity (DLT) was rash. At MTD (n=15), terminal phase half life (T½) of TA was 41 ± 25h and T½ of ADC was 29 ± 13h. Mean maximum plasma concentrations of free MMAE was 1.3–2.9% of TA concentration across all doses. Mean sGPNMB at baseline was 12 ng/ml (range 1.3–32 ng/ml), corresponding to 0.024 % of TA concentration at MTD. Anti-ADC Ab were detectible in 8/240 (3.3%) samples (n=54). Based on the T½, two additional dose schedules (qw and 2 out of 3w) were initiated (n=14). Pts received 0.75 mg/kg (n=3) and 1.0 mg/kg (n=5) in the qw schedule and 1.25 mg/kg (n=3) and 1.5 mg/kg (n=3) in 2 of 3w. The most common adverse events (AEs) were rash (n=6), pruritus (n=5) and fatigue (n=4). 1 DLT (Gr 3 rash) was observed at 1.0 mg/kg qw. Enrollment is ongoing in both schedules. Conclusions: The relatively short T½ of CR011-vcMMAE (∼40h) does not appear to be due to immunogenicity or sGPNMB-mediated clearance. Preliminary data suggest that weekly dosing is tolerated at higher per-cycle cumulative doses than the q3w schedule. [Table: see text]

14092 Background: Belinostat (PXD101) is a hydroxamate HDAC inhibitor which demonstrates broad anti-neoplastic activity in vitro and in vivo. In Phase I studies in patients (pts) with advanced cancer, IV belinostat is well-tolerated up to 1000 mg/m2 daily x5. Preliminary results of an oral formulation of belinostat showed that the oral bioavailability was 20 - 50%. This Phase I trial of oral belinostat will determine the maximal tolerated dose (MTD) of once and twice daily dosing, tolerability and pharmacokinetics (PK) in pts with advanced solid tumors. Methods: Sequential cohorts of 3–6 pts with advanced solid tumors refractory to standard therapy or for which no standard therapy exists were administered belinostat 250–500mg once or twice daily in 4 week cycles. Fasting (day 1) and non-fasting (day 7) pharmacokinetic studies were performed on all patients along with serial ECGs to evaluate any potential effects on QTc prolongation. Patients were evaluated with routine blood work weekly and tumor imaging at the end of cycle 1 then every other cycle. Results: Sixteen pts have been treated in 3 dose levels at 250mg QD (6 pts), 500mg QD (6 pts) and 250mg BID (4 pts). The median number of cycles of therapy is 1 (range 1–5), nine pts continue to be treated. The most common reasons for discontinuation were adverse event (3 pts) and PD (3 pts). No DLTs were identified at 250mg QD or 250mg BID. DLTs of grade 3 dehydration and grade 3 fatigue were reported at 500mg QD. In pts from the first 3 dose cohorts, there were no grade 4/5 events reported. Other Grade 3 toxicities were fatigue (2 pts), abdominal pain (1 pt), ataxia (1 pt), prolonged INR (1 pt), prolonged PTT (1 pt) and confusion (1 pt). Symptoms were transient and usually resolved after drug was held. In > 500 ECG’s collected, there were no QTcF > 500 ms, and no QTcF increase > 60 ms above baseline. To date, the best clinical response observed has been SD in 7 patients. Conclusions: Oral belinostat at doses of 250mg QD and 250mg BID given on a continuous schedule appears to be well tolerated. Alternative dosing schedules are being explored to further dose escalate the belinostat. Updated safety, activity and pharmacokinetic data will be presented on these and alternate dose schedules. [Table: see text]

3501 Background: PXD101 is a hydroxamate HDAC inhibitor that has broad anti-neoplastic activity in vivo and in vitro. Preclinical data showing PXD101 down-regulation of thymidylate synthase (TS), an in vivo target of 5-fluorouracil (5-FU) provide a rationale for combination of PXD101 with 5-FU. Methods: This is a phase Ib/II trial of PXD101 plus 5-FU in patients with advanced solid tumors, with dose escalation to establish the maximum tolerated dose (MTD) and an expansion at the MTD in colorectal cancer (CRC) patients. Patients (pts) must be = 18 yrs, have measurable disease, and had disease progression after standard chemotherapy. PXD101 was administered as a 30-min IV infusion on Days 1–5 of a 3-wk cycle. 5-FU was administered from cycle 2 on, as a continuous 96-hr IV infusion starting on Day 2 of the same 3-wk cycle. The primary endpoints were safety, and effect of belinostat on TS expression in patients’ tumors. Dose-limiting toxicities (DLTs) were PXD101-related = Gr 3 non-hematologic or Gr 4 hematologic toxicities. Expression of TS mRNA was measured by RTQ-PCR. Results: Twenty pts have been treated for a median of 2 cycles (range 1–8). Cohorts of 3–6 pts were tested at 5 dose levels of PXD101/5-FU (mg/m2/d): 300/250, 600/250, 1,000/250, 1,000/500, and 1,000/1,000. Two pts did not complete cycle 2, and one pt at the 600/250 dose level received 1,000 mg/m2/d 5-FU. There were no DLTs in the first 4 dose cohorts; the 5th cohort is ongoing. In the first 4 dose cohorts (17 pts), the most frequent AEs were fatigue, nausea/vomiting, dysgeusia, dehydration, constipation, edema, anorexia and anemia. There were 2 Gr 4 AEs (pulmonary embolism, bacteremia); Gr 3 AEs in = 2 pts were fatigue and dehydration. All Gr 3/4 events were assessed as not related to PXD101. One pt with stage IV CRC treated at 600/1,000 mg/m2/d PXD101/5-FU had stable disease (SD) for 8 cycles, and one pt with stage IV esophageal cancer treated at the 1,000/250 mg/m2/d dose had SD for 4 cycles. Conclusions: PXD101 in combination with 5-FU has been well tolerated up to 1,000/500 mg/m2/d PXD101/5-FU. The study is ongoing and data from the MTD expansion part, including effect of PXD101 on tumor TS expression, will be presented. No significant financial relationships to disclose.

Oral mucositis (OM) is a common complication in cancer patients receiving chemotherapy (CT). OM is characterized by damage to the epithelium of the oral-pharyngeal cavity. CG53135-05, a recombinant human fibroblastic growth factor 20 (rhFGF-20) protein, has demonstrated epithelial and mesenchymal cell proliferation stimulating activity in vitro and reduces OM using single doses in a hamster mucositis model. The goal of this dose-escalating tolerance study was to assess the safety, tolerability and pharmacokinetics of CG53135-05 in cohorts of four patients (pts) at 0.03, 0.1, 0.33, and 1mg/kg (concentrations are determined by the UV method which are equivalent to 0.1, 0.3, 1.0, and 3.0 mg/kg by the Bradford method previously used). Dose escalation was stopped due to tolerability information at 0.33 mg/kg delivered in 15 min (reported in another Phase I study) and the protocol was amended to add a 0.2 mg/kg dose. The World Health Organization (WHO) OM and OMAS scoring systems were used to measure the incidence and severity of OM. The interim results are reported: Ten pts received CG53135-05 at 0.03 mg/kg (n=4) or 0.1 mg/kg (n=6) as a single 100-ml intravenous infusion administered 3 days after completion of the CT. After infusion, CG53135-05 reached maximum plasma concentration within 1h. The mean terminal exponential half-life was 49 min (range: 16.2–87 min, n=5). No pts discontinued the trial due to adverse experiences. Adverse events (number pts) that may be related to the study drug include: nausea (2); chills (2); fever (2); vomiting (1); dizziness (1); vision - “lights flashing” (1) and astigmatism (1); neuropathy (1); tachycardia (1); headache (1); and premature atrial complex (1). All reported incidences were mild to moderate. No grade 3 or 4 laboratory toxicity associated with the study drug was noted. Three serious adverse events deemed unrelated to study drug were noted from two pts including cancer progression, catheter infection, and small intestinal obstruction. Among the treated pts, no grade 3 or 4 OM was observed. Three pts developed Grade 2 mucositis that lasted between 1–5 days. No pts required total parenteral nutrition. Approximately 72–84% of pts receiving CPT-11 experience diarrhea. Of the six pts who received CPT-11 as part of CT in this trial, two pts (both receiving 0.03mg/kg of CG53135-05) experienced mild to moderate diarrhea. Conclusions: CG53135-05 is well tolerated with single dose administration at 0.03 and 0.1 mg/kg. Dosing at 0.2 mg/kg is ongoing. The full results of this study will be presented.