PURPOSE Patients with metastatic colorectal cancer refractory to chemotherapy have limited treatment options. Ensituximab (NEO-102) is a novel chimeric mAb targeting a variant of MUC5AC with specificity to colorectal cancer. PATIENTS AND METHODS Single-arm, phase II trial assessed the efficacy and safety of ensituximab in patients with advanced, refractory cancer who expressed MUC5AC antigen in tumor tissue. Ensituximab was administered intravenously every 2 weeks with 3 mg/kg as recommended phase II dose (RP2D). A minimum sample size of 43 patients was required on the basis of the assumption that ensituximab would improve median overall survival (OS) by 7 months using a one-sided significance level of 10{\%} and 80{\%} power. Written informed consent was obtained from all patients. RESULTS Sixty-three patients with advanced, refractory colorectal cancer were enrolled and 53 subjects were treated in phase II arm. Median age was 58 years and 46{\%} of the patients were female. Among 57 evaluable patients, median OS was 6.8 months. No responses were observed, and stable disease was achieved in 21{\%} of the patients. The most common treatment-related adverse events (AE) at RP2D included fatigue (38{\%}), anemia (30{\%}), nausea (15{\%}), vomiting (11{\%}), increased bilirubin (9{\%}), constipation (8{\%}), decreased appetite (6{\%}), and diarrhea (6{\%}). Serious AEs at least possibly related to ensituximab occurred in 4 patients and included anemia, nausea, increased bilirubin, and hypoxia. No patients discontinued treatment due to drug-related AEs. CONCLUSIONS Ensituximab was well tolerated and demonstrated modest antitumor activity in patients with heavily pretreated refractory colorectal cancer.

Purpose: Despite high initial response rates with cytoreductive surgery, conventional chemotherapy and the incorporation of biologic agents, ovarian cancer patients often relapse and die from their disease. New approaches are needed to improve patient outcomes. This study was designed to evaluate the antitumor activity of NEO-201 monoclonal antibody (mAb) in preclinical models of ovarian cancer where the NEO-201 target is highly expressed. Experimental Design: Functional analysis of NEO-201 against tumor cell lines was performed by antibody-dependent cellular cytotoxicity (ADCC) assays. Binding of NEO-201 to tumor tissues and cell lines were determined by immunohistochemistry (IHC) and flow cytometry, respectively. Further characterization of the antigen recognized by NEO-201 was performed by mass spectrometry. Ovarian cancer models were used to evaluate the anti-tumor activity of NEO-201 in vivo. NEO-201 at a concentration of 250 g/mouse was injected intraperitoneally (IP) on days 1, 4, and 8. Human PBMCs were injected IP simultaneously as effector cells. Results: Both IHC and flow cytometry revealed that NEO-201 binds prominently to the colon, pancreatic, and mucinous ovarian cancer tissues and cell lines. Immunoprecipitation of the antigen recognized by NEO-201 was performed in human ovarian, colon, and pancreatic cancer cell lines. From these screening, carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and CEACAM6 were identified as the most likely targets of NEO-201. Our results confirmed that NEO-201 binds different types of cancers; the binding is highly selective for the tumor cells without cross reactivity with the surrounding healthy tissue. Functional analysis revealed that NEO-201 mediates ADCC killing against human ovarian and colorectal carcinoma cell lines in vitro. In addition, NEO-201 inhibited tumor growth in the presence of activated human PBMCs in orthotopic mouse models of both primary and metastatic ovarian cancer. Importantly, NEO-201 prolonged survival of tumor-bearing mice. Conclusions: These data suggested that NEO-201 has an antitumor activity against tumor cells expressing its antigen. Targeting an antigen expressed in tumors, but not in normal tissues, allows patient selection for optimal treatment. These findings strongly indicate that NEO-201 warrants clinical testing as both a novel therapeutic and diagnostic agent for treatment of ovarian carcinomas. A first in human clinical trial evaluating NEO-201 in adults with chemo-resistant solid tumors is ongoing at the NIH clinical Center.

Latent proviruses persist in central (TCM), transitional (TTM), and effector (TEM) memory cells. We measured the levels of cellular factors involved in HIV gene expression in these subsets. The highest levels of acetylated H4, active nuclear factor $\kappa$B (NF-$\kappa$B), and active positive transcription elongation factor b (P-TEFb) were measured in TEM, TCM, and TTM cells, respectively. Vorinostat and romidepsin display opposite abilities to induce H4 acetylation across subsets. Protein kinase C (PKC) agonists are more efficient at inducing NF-$\kappa$B phosphorylation in TCM cells but more potent at activating PTEF-b in the TEM subset. We selected the most efficient latency-reversing agents (LRAs) and measured their ability to reverse latency in each subset. While ingenol alone has modest activities in the three subsets, its combination with a histone deacetylase inhibitor (HDACi) dramatically increases latency reversal in TCM cells. Altogether, these results indicate that cellular HIV reservoirs are differentially responsive to common LRAs and suggest that combination of compounds will be required to achieve latency reversal in all subsets.