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Gating strategy for immune subsets in pancreatic tumor

Amino acid sequence of anti-MUC1.IgE antibody

Pancreatic ductal adenocarcinoma (PDAC) represents 3% of all cancer cases and 7% of all cancer deaths in the United States. Late diagnosis and inadequate response to standard chemotherapies contribute to an unfavorable prognosis and an overall 5-year survival rate of less than 10% in PDAC. Despite recent advances in tumor immunology, tumor-induced immunosuppression attenuates the immunotherapy response in PDAC. To date, studies have focused on IgG-based therapeutic strategies in PDAC. With the recent interest in IgE-based therapies in multiple solid tumors, we explored the MUC1-targeted IgE potential against pancreatic cancer. Our study demonstrates the notable expression of FceRI (receptor for IgE antibody) in tumors from PDAC patients. Our study showed that administration of MUC1 targeted-IgE (mouse/human chimeric anti-MUC1.IgE) antibody at intermittent levels in combination with checkpoint inhibitor (anti-PD-L1) and TLR3 agonist (PolyICLC) induces a robust antitumor response that is dependent on NK and CD8 T cells in pancreatic tumor-bearing mice. Subsequently, our study showed that the antigen specificity of the IgE antibody plays a vital role in executing the antitumor response as nonspecific IgE, induced by ovalbumin (OVA), failed to restrict tumor growth in pancreatic tumor-bearing mice. Utilizing the OVA-induced allergic asthma-PDAC model, we demonstrate that allergic phenotype induced by OVA cannot restrain pancreatic tumor growth in orthotopic tumor-bearing mice. Together, our data demonstrate the novel tumor protective benefits of tumor antigen-specific IgE-based therapeutics in a preclinical model of pancreatic cancer, which can open new avenues for future clinical interventions.

Objective Cancer antigen (CA)-125 influences progression, metastasis, and outcomes in pancreatic cancer. This phase I/II trial (NCT01959672) evaluated the safety, efficacy, and immunologic correlates of chemoimmunotherapy (CIT) with oregovomab (anti-CA-125), followed by stereotactic body radiotherapy (SBRT) with the radiosensitizer nelfinavir. Materials and methods Following imaging, pathologic confirmation, and staging laparoscopy, subjects received three 3-week cycles of CIT (gemcitabine/leucovorin/fluorouracil/oregovomab). Thereafter, nelfinavir was delivered (1250 mg bid) for 5 weeks, with SBRT (40 Gy/5 fractions) occurring during the third week of nelfinavir. Following another cycle of CIT, pancreaticoduodenectomy was performed if resectable. Three more cycles of CIT were then delivered (total 7 cycles). In subjects with high (≥10 U/mL) CA-125, oregovomab (2 mg) was administered for 7 total doses (3 pre-SBRT, 1 between SBRT and resection, and 3 postoperatively). The enzyme-linked immunospot assay evaluated the development of CA-125-specific CD8 T-lymphocytes. Results The trial was prematurely closed because gemcitabine/leucovorin/fluorouracil was replaced by FOLFIRINOX and gemcitabine/nab-paclitaxel as the standard of care. Median follow-up was 13 months. Of 11 enrolled patients, 10 had high CA-125; 1 patient suffered an unexpected cardiac-related death, so 9 subjects received oregovomab. Ten received SBRT and 4 underwent resection. Overall, 6/11 patients experienced any grade ≥3 event. The median survival and time to progression were 13 and 8.6 months, respectively. Five patients had samples available for immunospot testing, of whom 2 (40%) developed CA-125-specific CD8 T-lymphocytes. Conclusion A combined pancreatic cancer multimodality approach using CIT and radiosensitized radiotherapy is feasible and safe; delivery of immunotherapy can lead to T-cell immunity. Re-evaluation with modern systemic paradigms is recommended.

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The standard-of-care (SOC) first-line therapy for ovarian cancer (OC) patients is plagued with high relapse rates. Several studies indicated the immune system’s prominent role changing the disease course in OC patients. Chemo-immunotherapy regimens, currently being explored, include oregovomab, which is a monoclonal antibody specific for the OC associated antigen carbohydrate/cancer antigen 125 (CA125) that yielded promising results when administered together with SOC in a previous study. The QPT-ORE-002 multi-site phase II randomized study demonstrated that in patients with advanced OC, oregovomab combined with first-line SOC improved overall and progression-free survival, compared to SOC alone. The study included an Italian cohort in which we demonstrated that adding oregovomab to SOC resulted in increased patient numbers with amplified CA125-specific CD8+T lymphocytes/ml peripheral blood counts, which might explain the improved therapeutic effect of SOC + oregovomab over SOC alone. Predictive for oregovomab efficacy was a less suppressive immune environment at baseline as indicated by low numbers of circulating myeloid-derived suppressor cells, subset type 4, and a low neutrophil-and-monocyte to lymphocyte ratio.

Background This randomized phase II study tested the hypothesis that schedule dependent chemo-immunotherapy with oregovomab improves progression free survival (PFS) and overall survival (OS) in optimally resected, Stage III/IV ovarian cancer. Methods Patients from both academic centers and private practice in the US and Italy with Stage III/IV optimally cytoreduced ovarian cancer were randomized to standard six cycle IV carboplatin-paclitaxel chemotherapy (CP) versus CP plus four immunizations with oregovomab (CPO). A translational assessment of a cellular immune response was the primary endpoint; PFS and OS were measured as secondary endpoints. Findings 97 patients at thirteen centers were accrued to the protocol, 47 to CPO and 50 to CP. Technical issues led to inconsistent performance of the primary CA125 ELISPOT leading to unevaluable results. At a median follow up of 42 months, PFS and OS outcomes revealed an unexpectedly large treatment effect for CPO relative to CP alone, with median PFS of 41.8 months (95% C.I.: 21.8 - N.E.) for CPO and 12.2 months (10.4–18.6) for CP (p = 0.0027, HR 0.46, CI 0.28–0.7). For OS, the median for CPO has not yet been reached (NE) (45.2-NE) and for CP was 43.2 months (31.8-NE) (p = 0.043, HR 0.35, CI 0.16–0.74). The oregovomab treatment resulted in no change in toxicity profile from CP. Interpretation The previously identified potential clinical benefit of IV CP when administered with oregovomab was further refined in this randomized phase II study. Increases of PFS and OS of statistically and clinically significant magnitude were evident in this study of a front line chemo-immunotherapy treatment of ovarian cancer.

A substantial body of evidence suggests the existence of MUC1-specific antibodies and cytotoxic T cell activities in pancreatic cancer patients. However, tumor-induced immunosuppression renders these responses ineffective. The current study explores a novel therapeutic combination wherein tumor-bearing hosts can be immunologically primed with their own antigen, through opsonization with a tumor antigen-targeted antibody, mAb-AR20.5. We evaluated the efficacy of immunization with this antibody in combination with PolyICLC and anti-PD-L1. The therapeutic combination of mAb-AR20.5 + anti-PD-L1 + PolyICLC induced rejection of human MUC1 expressing tumors and provided a long-lasting, MUC1-specific cellular immune response, which could be adoptively transferred and shown to provide protection against tumor challenge in human MUC1 transgenic (MUC.Tg) mice. Furthermore, antibody depletion studies revealed that CD8 cells were effectors for the MUC1-specific immune response generated by the mAb-AR20.5 + anti-PD-L1 + PolyICLC combination. Multichromatic flow cytometry data analysis demonstrated a significant increase over time in circulating, activated CD8 T cells, CD3+CD4-CD8-(DN) T cells, and mature dendritic cells in mAb-AR20.5 + anti-PD-L1 + PolyICLC combination-treated, tumor-bearing mice, as compared to saline-treated control counterparts. Our study provides a proof of principle that an effective and long-lasting anti-tumor cellular immunity can be achieved in pancreatic tumor-bearing hosts against their own antigen (MUC1), which can be further potentiated using a vaccine adjuvant and an immune checkpoint inhibitor.

e17545 Background: Indirect immunization with tumor specific antibody is an approach to triggering therapeutic immunity to cancer through activated immune cells. O is a monoclonal IgG1 specific to CA125 (MUC16). O is currently in phase III evaluation of front-line chemoimmunotherapy (CIT), having shown benefit relative to chemotherapy alone in a randomized phase II study (Brewer, Gyn Onc 2020). H is a TLR3 agonist used as a stimulatory immune adjuvant. The dosing phase of the protocol established safety and compatibility of this combination. The primary safety and response outcomes were reported at IGCS-2019. Immune parameters and long-term outcome associations are the focus of this final update. Methods: Pts with heavily treated RECIST evaluable platinum resistant ovarian cancer (median of 5 prior Rx) received 4 IV infusions with 2 mg O followed by 2mg H IM 30 min & 48 hrs post O at wks 0, 3, 6, 9. At wk 12 imaging was performed and elective salvage Rx allowed. A fifth O+H was optional at wk 16. Study endpoints included immune associations after O+H, after second-line chemotherapy, and survival outcomes. Results: 17 pts were enrolled at 2 centers; 15 patients were dosed and 13 completed the specified minimum 3 infusions. The treatment was well tolerated with local reactions and mild flu like symptoms (13/15 pts) as the only reported adverse events. There was no treatment related serious adverse events. Median survival was 15.0 m [95% CI:10.8m-NE] and 4 patients remained alive at data lock (median 26.5 m). H stimulated an early humoral antibody response to O at wk 6 in 7 of 9 pts (78%). Interval administration of second-line Rx (bevacizumab, paclitaxel, carboplatin, &/or doxorubicin) and O were associated with further antibody spikes. Baseline neutrophil monocyte to lymphocyte ratio (NMLR), a measure of myeloid-derived immune suppression was inversely associated with survival. PROC patients with baseline NMLR ≤4x (n = 8) had median OS 19.6m [15.0 m -NE] vs median OS 10.8m [3.6m-NE] HR 2.44 [0.73-8.15], ( p= 0.13) for pts with NMLR > 4.0 (n = 7). Conclusions: H is a viable immune adjuvant for combination with O suitable for further study in immune resistant settings. Immune responsiveness was similar to that observed in a prior study of same day schedule of carboplatin-paclitaxel front-line immunotherapy (Braly, JIT 2009; Battaglia, Cll, 2020). Patterns of immune response to O in the setting of recurrent ovarian cancer are influenced by concomitant anti-neoplastic therapy. Clinical outcomes appear sensitive to myeloid burden (NMLR > 4) which may be more prevalent in patients with treatment resistant disease than in chemotherapy naïve patients, as previously observed in front-line CIT trials. A phase III study to further evaluate these associations in the front-line setting is currently underway NCT04498117. Clinical trial information: NCT03162562.

Recent years have witnessed an increased incidence of pancreatic adenocarcinoma (PDAC). Pancreatic tumors are poorly immunogenic; current immunotherapeutic strategies largely focus on boosting adaptive immunity while ignoring immunosuppressed innate immune players such as natural killer cells (NKs). NK cells respond to tumor insults by generating IFN-γ for T-cell activation. Multiple studies suggest that tumor cells evade NK cell-mediated killing by 1) developing “escape variants” and 2) regulating inhibitory and activating receptors on NK cells, imparting anergic/exhaustive phenotype inside the pancreatic tumor microenvironment. We posit that a therapeutic combination that not only overturns tumor-mediated NKs dysfunction but also boosts cytotoxic CD8 T cells will provide long-lasting therapeutic benefits in PDAC. Given this, we explored the efficacy of a unique therapeutic combination, tumor antigen-targeted IgE antibody (humanized anti-MUC1.IgE) in combination of anti-PD-L1 (for relieving T-cell exhaustion) and PolyICLC (for dendritic cell maturation) in a preclinical model of pancreatic cancer using mice transgenic for human MUC1 and FcϵRI (hMUC1/hFcϵRI). This therapeutic combination induced MUC1 specific rejection of two different human MUC1-expressing pancreatic tumor cell lines (Panc02.MUC1, KPC.MUC1) and prolonged the overall survival of mice challenged with subcutaneous and orthotopic tumors as compared to control counterparts. Additionally, this combination generated CD8 T-cell memory response as evidenced by MUC1 specific rejection/delays of tumors in mice rechallenged with MUC1-expressing tumors. Cytokine/chemokine profiling of anti-MUC1.IgE+anti-PD-L1+PolyICLC treated tumors further demonstrates a reduction in proinflammatory cytokines as compared to control counterparts. Most importantly, NK and CD8 T cells were involved in cell-mediated antitumor responses, as in vivo depletion of these subtypes abrogated the tumor-protective benefits in mice bearing orthotopic tumors. Anti-MUC1.IgE+anti-PD-L1+PolyICLC combination appears to increase circulating NKs and reverse NK cell exhaustion inside pancreatic tumor microenvironment. Additional data suggest that this therapeutic combination boosts tumor cell killing by NK cells in antibody-dependent cell cytotoxicity assays (ADCC). In sum, this is the first study to show that specific stimulation of IgE/FcϵRI axis in combination with PolyICLC and anti-PD-L1 can activate both CD8 T and NK cell effector pathways and provide long-lasting tumor-protective benefits against pancreatic cancer. This abstract is also being presented as Poster A48. Citation Format: Kamiya Mehla, Thomas C. Caffrey, Kelly A. O'Connel, Raghupathy Madiyalakan, Christopher F. Nicodemus, Michael A. Hollingsworth. A novel NK cell-targeted therapeutic strategy against pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr PR15.

Monoclonal antibodies remain a primary product option for novel cancer treatment. The properties of an antibody are a function of the antigen specificity and constant region incorporated. The rapid advance in molecular understanding of cancer biology and the host–tumor interaction has defined a new range of targets for antibody development. The clinical success of the checkpoint inhibitors has validated immune modulation and mobilization as a therapeutic approach. Solid cancers are distinguished from hematologic malignancies because the solid tumor stroma contains significant tumor promoting and immune dampening elements less prominent in hematologic cancer. This review highlights how engineered monoclonal antibody products are emerging as potential cornerstones of new more personalized cancer treatment paradigms that target both tumor and the stromal environment.

Toll-like receptors (TLRs) are highly conserved type 1 membrane proteins that initiate a multiplicity of transient gene transcriptions, resulting in innate and adaptive immune responses. These essential immune responses are triggered by common TLR pattern recognition receptors of microbial products expressed through the cytoplasmic carboxy-terminal Toll/IL-1 domain. Toll/IL-1 adapter protein cascades are induced by an activated Toll/IL-1 to induce transient transcription responses. All TLRs, with the exception of TLR3, use an MyD88 adapter to Toll/IL-1 to initiate a proinflammatory cascade. TLR3 uses the toll receptor 3/4 induction factor adapter to initiate a different cytosolic adapter cascade with double-stranded RNA agonists. This non-MyD88 pathway induces both NF-κB and type 1 interferon responses. By using a TLR3-restricted double-stranded RNA agonist, rintatolimod, we demonstrate significant unexpected differences in toxic responses between rats and primates. The mechanism of this differential response is consistent with a relative down-regulation of the NF-κB inflammatory cytokine induction pathway in the cynomolgus monkey and humans, but not observed systemically in rat. Our findings suggest evaluation of TLR3 agonists in drug therapy.

e16202Background: CA-125, a tumor marker expressed in > 50% pancreatic adenocarcinoma (PAC), was targeted with oregovomab (O), a monoclonal antibody currently in development as chemoimmunotherapy (...

Purpose This phase III study tested the hypothesis that the CA-125–specific murine monoclonal antibody, oregovomab, administered as a monoimmunotherapy after front-line therapy in a selected ovarian cancer population would prolong time to relapse (TTR) and, ultimately, survival. Patients and Methods Patients with stage III to IV ovarian cancer with preoperatively elevated CA-125 and objectively defined characteristics were randomly assigned 4 to 12 weeks after front-line carboplatin and paclitaxel chemotherapy to maintenance monoimmunotherapy in a fully blinded protocol. Two mg of oregovomab or placebo was infused over 20 minutes at weeks 0, 4, and 8 and then 12 weeks until recurrence or up to year 5. Patients were evaluated with serial imaging and clinical evaluation for evidence of recurrence at quarterly visits. TTR was the primary end point. Results Three hundred seventy-three patients were accrued at more than 60 centers; 251 patients were assigned to oregovomab and 120 patients were assigned to placebo. The treatment arms were well balanced. There were no differences in the clinical outcomes between treatment groups. Median TTR measured from randomization after completion of chemotherapy for the integrated study was 10.3 months (95% CI, 9.7 to 13.0 months) for oregovomab and 12.9 months (95% CI, 10.1 to 17.4 months) for placebo (P = .29, log-rank test). The treatment was well tolerated. Grade 3 to 4 toxicity was reported in 24.6% of patients in the placebo group and 20.1% of patients in the oregovomab group, respectively. Conclusion Although oregovomab has demonstrated bioactivity, the strategy of monoimmunotherapy is not effective as maintenance therapy after front-line treatment of a favorable subset of patients with advanced ovarian cancer. Future studies of this or other tumor-antigen specific immunization strategies should seek ways to further augment induced immunity.

Oregovomab is a monoclonal antibody that recognizes CA125 and forms circulating immune complexes that can elicit immunity against both tumor antigen and tumor. This study was designed to assess combining this immunotherapy at 2 dosing schedules with front-line chemotherapy in patients with advanced ovarian cancer. Forty patients with stage III/IV carcinomas were randomized to receive a 2 mg oregovomab infusion either the same day [simultaneous infusion (SIM)] or 1 week after [1-week delayed (OWD)] standard carboplatin-paclitaxel chemotherapy at cycles 1, 3, and 5, then quarterly for up to 11 antibody doses. The primary end point was antibody response to oregovomab. Secondary end points included cellular immune response, response rate to front-line treatment, and progression-free survival. A different immune response pattern was observed between the SIM arm and the OWD arm, baseline plasma cytokines were balanced. Humoral immunity occurred more rapidly (P=0.0033) and with greater magnitude in the SIM arm. Absolute lymphocyte counts decreased in the SIM arm at cycles 3 and 5 compared with baseline. Treatment emergent CA125-specific cellular immunity was measured more commonly with SIM (P=0.04) and clinical parameters directionally favored this schedule. The immune responses were stronger than those measured in a previous maintenance monoimmunotherapy protocol. Immunotherapy-associated toxicity was minimal in this study. Front-line chemotherapy with carboplatin-paclitaxel has immune adjuvant properties when combined with oregovomab immunotherapy; however, schedule is important. SIM strategies of carboplatin and paclitaxel should be further studied with oregovomab and other antigen-specific cancer immunotherapy approaches.

Monoclonal antibodies, considered to be ‘magic bullets’ 20 years ago, may finally be realizing their full potential, particularly in the area of oncology, where > 10 monoclonal antibodies are approved for treatment. Monoclonal antibodies are being used to modulate tumor-specific immunity through several approaches: antibodies that direct cytotoxicity against the tumor through cellular or complement-mediated pathways; antibodies that directly modulate immune regulation; antibodies that alter tolerance to tumor antigens; and antibodies that act as antigen mimetics through the anti-idiotype network. Therapeutic progress in these areas is reviewed as well as the potential to combine these approaches with standard therapies.

Biologic therapy of ovarian cancer has been conducted using nonspecific biologic response modifiers, cytokines, monoclonal antibodies (MAbs), vaccines, and gene therapy. Antibodies directed toward her2/neu have also been studied. Phase I and II gene therapy trials using adenoviral vectors containing a wild-type or modified p53 have shown that the treatment is well tolerated. Phase II and III trials are ongoing with MAbs directed against CA-125 (MAb B43.13) and an antibody directed against HMFG1 (anti-HMFG1-yttrium-90-labeled antibody). The trials have shown that these agents are well tolerated and that immunologic responses occur, although the ultimate clinical value of these agents remains to be determined. Prolonged survival after MAb B43.13 treatment has been correlated with changes in several immune parameters, including human antimurine antibody, Ab2, anti-CA-125 antibody development, and induced T-cell immunity. Clinical trials using a MAb directed toward the encoded products of her2/neu have shown minimal activity against ovarian cancer in a phase I and II trial conducted by the Gynecologic Oncology Group. Cytokine therapies have been administered systemically and intraperitoneally. Intracavitary interferon alfa, interferon gamma, and interleukin-2 alone or in combination with cytotoxic therapy in phase I and II trials demonstrated intraperitoneal lymphoid cell stimulation and produced antitumor responses. A randomized trial of chemotherapy with or without interferon gamma in primary treatment produced a response and a progression-free survival advantage in the arm that incorporated the interferon gamma, without a statistically significant benefit in overall survival. A phase III study of interferon gamma in combination with first-line chemotherapy is currently ongoing.

This review identifies the role of antibodies in the field of therapeutic cancer vaccines. Ovarian cancer is used as a model to review advances in therapeutic vaccine development with a focus on antibodies as immunomodulators and antigen mimetics, highlighting research on B43.13 and ACA125. The interaction of biological immunomodulation and chemotherapy is discussed. Requirements of antigen processing and recent advances in the field of dendritic cell biology are critical to current understanding of potent immune response induction. Future directions including use of growth factors, adjuvants and cellular therapies to enhance effects may potentiate observed effects and provide clues for application in many cancers and beyond oncology.

5536 Background: In a phase II study of vaccination schedule in front-line combinatorial treatment of EOC (Braly JIT 2009), simultaneous day infusion dramatically enhanced the magnitude of induced immunity relative to a one week delayed schedule & other schedules historically evaluated. The current study is exploring the clinical & biological effects of the optimized 4 vaccine schedule relative to CP alone. Methods: Stage III/IV EOC patients (pts) optimally debulked to 2x ULN were randomized to CP+O (cycle 1,3,5, & C5 +12 weeks) vs CP and followed for clinical outcomes and immune reponse. A total of at least 80 evaluable pts were required for 80% power to detect a difference of 45% vs 15% for a primary comparative analysis of induced CA125 specific T cell immunity using an IFN-γ ELISpot. Clinical evaluations and safety were considered secondary endpoints. Results: 97 pts (47 OV+SOC & 50 SOC) were accrued at 13 centers in US & Italy. Analysis of immune markers and long term clinical outcomes is ongoing. The median duration of follow up at time of this analysis was 26 months (m). There was no difference in safety outcomes between the treatment groups. Grade 3-4 toxicity was observed in 24 (52%) CP+O vs 28 (58%) C-P pts. Toxicities were typical of standard IV C-P chemotherapy. K-M Analysis of recurrence free survival (RFS) showed median RFS not estimable for CP+O [95% CI: 21.3, NE] vs 15.4 m [10.9,19.3] for CP (p=0.0009 log rank). In the interim analysis of survival (OS), 4 deaths have been observed in CP+O vs 16 in CP (log rank p=0.0025). Cox proportional hazard analysis finds consistent results across centers, and no imbalance in identified risk factors explanatory for the emerging outcome Conclusions: This study suggests simultaneous day vaccination with O on alternate cycles of front line CP leverages CP associated temporal change in the tumor microenvironment permitting an immune treatment effect to enhance the outcomes achievable with CP alone. This observation will be further characterized in ongoing translational studies and confirmed in a future phase III study. Clinical trial information: NCT01616303.

Pancreatic cancer is a fourth leading cause of cancer death in United States. Recent advances in tumor immunology have provided evidence for immune surveillance against pancreatic cancer. Previous studies have documented the presence of specific antibodies and cytotoxic T cell activities to Mucin 1 (MUC1), an antigen that is expressed in most pancreatic cancers. Hence, MUC1 remains a candidate for immunotherapeutic strategies for pancreatic cancer. Numerous attempts have been made to target this mucin glycoprotein; however, these efforts have shown only moderate success in part due to the complexity of the pancreatic tumor microenvironment. Previously, administration of murine monoclonal antibody BrevaRexAb-AR20.5 alone produced MUC1 specific immune response in a phase I study of advanced cancer patients, including increased human anti-MUC1 antibody levels and MUC1 specific T cell response in few patients. Though this was a phase I study, modest changes in tumor marker (CA15.3) but no anecdotal anti-tumor activity was observed in this small group of patients. Moving forward it is obvious that future immunization strategies should include other immune-modulators to amplify MUC1 specific immune responses of mAbAR20.5 and enhance other factors that contribute to tumor rejection. To that end, we investigated the anti-tumor effect of mAbAR20.5 in combination with anti-PD-L1 and poly (I:C) in murine models of pancreatic adenocarcinoma using human MUC1 expressing transgenic (hMUC1.Tg) mice, which are immunologically tolerant to MUC1. The therapeutic combination of mAb-AR20.5+anti-PD-L1+Poly (I:C) induced rejection or significant inhibition of tumor growth for two different MUC1 expressing pancreatic tumor cell lines, which was accompanied by persistent MUC1 specific memory immune response, which could be adoptively transferred to other mice and shown to protect against subsequent tumor challenge. We show that the anti-tumor response was effected by CD8 T cells, as their abrogation attenuated the anti-tumor response. Flow cytometric analysis of immunized mice demonstrated progressive increases in activated CD8 T cells in the peripheral circulation of combination treated mice. Together, these data support the hypothesis that targeting checkpoint induced immunosuppression (anti-PD-L1) together with the use of toll-like receptor 3 agonist as an adjuvant (poly (I:C) ) enhances the capacity of mAbAR20.5 to induce specific cell mediated immune responses to MUC1, which in turn provide long lasting anti-tumor response against pancreatic tumors. Our study supports the rapid translation of this strategy into clinical trials for pancreatic cancer patients. Citation Format: Kamiya Mehla, James A. Grunkemeyer, Kelly A. O'Connell, Maria M. Steele, Thomas Caffrey, Ragupathy Madiyalakan, Christopher F. Nicodemus, Michael A. Hollingsworth. AR20.5-based novel immunotherapy for pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A30.

Cells producing a T(H2)-cytokine profile play an important role in the onset and maintenance of atopic diseases, and therefore specific immunotherapy is aimed to induce a switch to cells producing a T(H1)- or T(H0)-cytokine profile. Recently, a novel form of immunotherapy making use of synthetic peptides from the major cat allergen Fel d 1 has been developed, but its mechanisms of action are unknown.We examined the effects of immunotherapy with Fel d 1 peptides on the response to bronchial provocation tests (PD20FEV1) with a standardized Fel d 1 cat extract on Fel d 1-specific serum IgE and IgG levels and in vitro IL-4 and IFN-gamma production.Patients allergic to cats received 6 weekly injections of 7.5 micro(g) (low dose), 75 micro(g) (medium dose), or 750 micro(g) (high dose) of Fel d 1 peptides (25 patients) or a placebo (6 patients).Six weeks after ending immunotherapy, posttreatment PD20FEV1 was not significantly different between the treated and placebo groups. However, in the medium- and high-dose groups there was a significant improvement between baseline and posttreatment days. IL-4 release was significantly reduced in the high dose-treated group (P.005, Wilcoxon W test), whereas it was unchanged in the low or medium dose- and in the placebo-treated groups. In all groups, IFN-gamma, IgE, and IgG levels remained unchanged.There was no correlation between the improvement of PD20FEV1 and the decrease in IL-4 production. These data suggest that peptide immunotherapy may act by shifting the Fel d 1-induced response of PBMCs in vitro from the T(H2)-like to the T(H0)-like phenotype.

Background: Peptide therapy targets T cells directly with short peptides containing multiple T-cell receptor epitopes. Murine studies suggest T-cell anergy as the mechanism of action; however, changes in T-cell cytokine profiles may be more relevant in human beings. Objective: We sought to study the effects of peptide therapy on ex vivo antigen-specific T-cell responses. Methods: Antigen-specific T-cell lines were generated from subjects enrolled in a double-blind, placebo controlled, two-dose study of the ALLERVAX CAT therapeutic, containing Fel d 1 peptides (ImmuLogic Pharmaceutical Corp., Waltham, Mass.) ( n = 7, 8, and 7, respectively, for groups receiving placebo, 75 μg, or 750 μg). Each subject had three lines propagated before and after receiving peptide therapy; antigens used were cat hair extract, Fel d 1 peptides, and tetanus toxoid (negative control). Proliferative responses and cytokine generation from each line were assessed after two restimulations with antigen and autologous antigen-presenting cells. Results: The Fel d 1 peptide lines showed a dose-dependent decrease of IL-4 production ( p = 0.02 and 0.025, respectively, for the 750 μg group vs both the 75 μg and placebo groups). IL-4 production from the cat hair allergen extract lines and interferon-γ production from both the Fel d 1 peptide lines and cat hair allergen extract lines showed no statistically significant changes. The control tetanus toxoid lines showed no changes in cytokine production; there were no significant changes in proliferation with any of the antigens in any of the treatment groups. In the clinical arm of the trial, only the 750 μg dose of peptides produced a significant response. Conclusions: Peptide therapy induces a significant, dose-dependent decrease in peptide-stimulated IL-4 production, consistent with either a shift in T-cell phenotype or peptide-specific T-cell tolerance. (J Allergy Clin Immunol 1998;101:506-13.)

Because in humans mast cells and basophils tend to possess nonsegmented and segmented/multi-lobular nuclei, respectively, nuclear morphology has been a major criterion for assessing the lineage of metachromatic cells of hematopoietic origin. Immature metachromatic cells with mono- and multi-lobular nuclei were both obtained when bone marrow cells from BALB/c mice were cultured for 3 weeks in the presence of interleukin-3. Analogous to the indigenous mature mast cells that reside in the peritoneal cavity and skin, both populations of in vitro–derived cells expressed the surface receptor c-kit, the chymase mouse mast cell protease (mMCP) 5, the tryptase mMCP-6, and the exopeptidase carboxypeptidase A (mMC-CPA). Immunogold electron microscopy confirmed the granule location of mMC-CPA and mMCP-6 in both populations of cells, and cytochemical analysis confirmed the presence of chymotryptic enzymes in the granules. Because mature mast cells possessing multi-lobular nuclei also were occasionally found in the skeletal muscle and jejunum of the BALB/c mouse, the V3 mouse mast cell line was used to investigate the developmental relationship of mast cells that have very different nuclear structures. After the adoptive transfer of V3 mast cells into BALB/c mice, v-abl–immortalized mast cells with mono- and multi-lobular nuclei were detected in the lymph nodes and other tissues of the mastocytosis mice that expressed c-kit, mMCP-5, mMCP-6, and mMC-CPA. These studies indicate that mouse mast cells can exhibit varied nuclear profiles. Moreover, the nuclear morphology of this cell type gives no insight as to its protease phenotype or stage of development.

Prostate cancer (PCa) is the second leading cause of cancer deaths in men in the United States. The prostate-specific antigen (PSA), often found at high levels in the serum of PCa patients, has been used as a marker for PCa detection and as a target of immunotherapy. The murine IgG1 monoclonal antibody AR47.47, specific for human PSA, has been shown to enhance antigen presentation by human dendritic cells and induce both CD4 andCD8 T-cell activation when complexed with PSA. In this study, we explored the properties of a novel mouse/human chimeric anti-PSA IgE containing the variable regions of AR47.47 as a potential therapy for PCa. Our goal was to take advantage of the unique properties of IgE in order to trigger immune activation against PCa. Fil: Daniels-Wells, Tracy R. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; Fil: Helguera, Gustavo Fernando. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Tecnologia Farmaceutica; Argentina; University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; Fil: Leuchter, Richard K. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; Fil: Quintero, Rafael. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; Fil: Kozman, Maggie. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; Fil: Rodríguez, José A.. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; University of California. The Molecular Biology Institute; Estados Unidos de América; Fil: Ortiz-Sánchez, E. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; Biomedical Research in Cancer. Basic Research Division. National Institute of Cancerology; Mexico.; Fil: Martínez-Maza, Otonel. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; Fil: Schultes, Brigit C.. Advanced Immune Therapeutics; Estados Unidos de América; Fil: Nicodemus Christopher. Advanced Immune Therapeutics; Estados Unidos de América; Fil: Penichet, Manuel. University of California. David Geffen School of Medicine. Department of Surgery. Division of Surgical Oncology; Estados Unidos de América; University of California. The Molecular Biology Institute; Estados Unidos de América

Many potential users of the H1 antihistamine cetirizine are asthmatic and may be using inhaled albuterol. This study was conducted to assess the possible bronchodilatory effect of cetirizine in patients with mild-to-moderate asthma and to determine whether cetirizine interacts with albuterol.In a randomized, double-blind, placebo-controlled, crossover study, the effects on pulmonary function of 5, 10, and 20 mg oral doses of cetirizine with and without inhaled albuterol (180 micrograms) were determined in 12 patients at 11 time points over 8 hours. The primary measure of efficacy was forced expiratory volume in 1 second (FEV1).Cetirizine with or without albuterol significantly increased FEV1, peak expiratory flow rate, and forced expiratory flow rate between 25% and 75% of vital capacity relative to baseline and placebo but did not have a significant effect on forced vital capacity. The effect of 20 mg of cetirizine on FEV1 was generally greater than that of 10 or 5 mg, but the difference was statistically significant only at the 30-minute time point (p0.05). All three cetirizine doses produced significantly greater increases than placebo in FEV1 and forced expiratory flow rate between 25% and 75% of vital capacity for 8 hours and in peak expiratory flow rate for 7 hours (p0.02). Albuterol alone had a significant effect on the four pulmonary function variables from 1 to 5 hours after baseline (p0.05), which is consistent with albuterol's recommended dosing frequency of every 4 to 6 hours. Albuterol alone increased FEV1 significantly more than 5 mg of cetirizine alone but not 10 mg or 20 mg of cetirizine alone at 60, 90, and 120 minutes after baseline, but all three doses of cetirizine increased FEV1 significantly more than albuterol 7 and 8 hours after baseline (p0.05), indicating that the bronchodilatory action of cetirizine lasts longer than that of albuterol. Cetirizine neither potentiated nor inhibited the bronchodilatory action of albuterol, but the two drugs appeared to have an additive bronchodilatory effect. None of the cetirizine treatments caused a worsening of pulmonary function, and all were well tolerated.Cetirizine has a significant bronchodilatory effect in patients with mild-to-moderate asthma and can be used to treat concomitant conditions (e.g., allergic rhinitis) without concern that it will interfere with the bronchodilatory effect of albuterol or cause worsening of asthma by itself.

Breast and ovarian cancer are two of the leading causes of cancer deaths among women in the United States. Overexpression of the HER2/neu oncoprotein has been reported in patients affected with breast and ovarian cancers, and is associated with poor prognosis. To develop a novel targeted therapy for HER2/neu expressing tumors, we have constructed a fully human IgE with the variable regions of the scFv C6MH3-B1 specific for HER2/neu. This antibody was expressed in murine myeloma cells and was properly assembled and secreted. The Fc region of this antibody triggers in vitro degranulation of rat basophilic cells expressing human FcεRI (RBL SX-38) in the presence of murine mammary carcinoma cells that express human HER2/neu (D2F2/E2), but not the shed (soluble) antigen (ECDHER2) alone. This IgE is also capable of inducing passive cutaneous anaphylaxis in a human FcεRIα transgenic mouse model, in the presence of a cross-linking antibody, but not in the presence of soluble ECDHER2. Additionally, IgE enhances antigen presentation in human dendritic cells and facilitates cross-priming, suggesting that the antibody is able to stimulate a secondary T-cell anti-tumor response. Furthermore, we show that this IgE significantly prolongs survival of human FcεRIα transgenic mice bearing D2F2/E2 tumors. We also report that the anti-HER2/neu IgE is well tolerated in a preliminary study conducted in Macaca fascicularis (cynomolgus) monkeys. In summary, our results suggest that this IgE should be further explored as a potential therapeutic against HER2/neu overexpressing tumors, such as breast and ovarian cancers. Fil: Daniels, Tracy R.. University of California at Los Angeles; Estados Unidos Fil: Leuchter, Richard K.. University of California at Los Angeles; Estados Unidos Fil: Quintero, Rafaela. University of California; Estados Unidos Fil: Helguera, Gustavo Fernando. University of California at Los Angeles; Estados Unidos. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rodríguez, José A.. University of California at Los Angeles; Estados Unidos Fil: Martínez Maza, Otoniel. University of California at Los Angeles; Estados Unidos Fil: Schultes, Birgit C.. Advanced Immune Therapeutics, Inc.; Estados Unidos. Momenta Pharmaceuticals, Inc.; Estados Unidos Fil: Nicodemus, Christopher F.. Advanced Immune Therapeutics, Inc.; Estados Unidos Fil: Penichet, Manuel L.. University of California at Los Angeles; Estados Unidos

A human cell strain (designated HBM-M) that was derived from the bone marrow of a child with diffuse cutaneous mastocytosis was previously found to possess features that suggested it belonged in the mast cell/monocyte lineage. HBM-M cells synthesized approximately 150-Kd Pronase-resistant proteoglycans that were recognized by an antihuman secretory granule proteoglycan peptide core antibody. These cells also contained in relatively high abundance the same sized mRNA transcript that encodes the peptide core of proteoglycans that are normally localized to secretory granules of hematopoietic cells. However, unlike most other hematopoietic cells, HBM-M cells continuously released their newly synthesized 35S-labeled proteoglycans rather than retaining them in an intracellular storage compartment. Chondroitinase ABC, nitrous acid, and heparinase degraded approximately 76%, 17%, and 7%, respectively, of the HBM-M cell-derived 35S-labeled proteoglycans. As assessed by high performance liquid chromatography, 91% of the unsaturated 35S-labeled disaccharides generated by treatment with chondroitinase ABC were delta Di-4S. The remaining chondroitin sulfate 35S-labeled disaccharides appeared to be primarily a complex mixture of disulfated disaccharides. The 35S-labeled glycosaminoglycans that were not degraded by chondroitinase ABC migrated in two-dimensional cellulose acetate electrophoresis as if they were heparan sulfate or under-sulfated heparin. Thus, although the HBM-M cell-derived proteoglycans had some of the features of proteoglycans produced by normal human mast cells, the heparin-like and chondroitin sulfate glycosaminoglycans bound to the HBM-M cell proteoglycans were considerably less sulfated. Because the only human cell types that have so far been shown to synthesize proteoglycans that have heparin-like glycosaminoglycans bound to a protease-resistant peptide core are mast cells and basophilic leukocytes from patients with myelogenous leukemia, it is possible that the HBM-M cell is a mast cell progenitor cell.

Objective The purpose of this study was to explore the potential of toll-like receptor-3 stimulation, with polyI:C 12 U (poly[l].poly[C 12 ,U]; rintatolimod [Ampligen; Hemispherx Biopharma, Philadelphia, PA]) to enhance bioactivity of cancer immunotherapies. Study Design Several models of immune activation were assessed with polyI:C 12 U at concentrations that were achieved clinically. Dendritic cell maturation and antigen-specific immune responses were evaluated in vitro and in a murine model. The potential for polyI:C 12 U to enhance antibody-dependent cellular cytotoxicity against tumor was also evaluated. Results Dendritic cells are matured and T-cell stimulation is enhanced in the presence of polyI:C 12 U. In addition, polyI:C 12 U induced the release of proinflammatory chemokines and cytokines. Prostate-specific antigen-specific T-cell and antibody responses were enhanced significantly in a BALB/c prostate-specific antigen transgenic mouse model. Finally, rituximab-mediated antibody-dependent cellular cytotoxicity against tumor targets was improved significantly by the addition of polyI:C 12 U. Conclusion PolyI:C 12 U shows promise as a potential agent for selective enhancement of effect with currently available and future cancer immunotherapies.

This report presents final survival survey results from a previously reported study using oregovomab immunotherapy in patients with advanced ovarian epithelial cancer. Follow-up surveys to 5 years from randomization were collected for the cohort of stage III/IV ovarian cancer patients achieving initial remission who received subsequent maintenance immunotherapy with oregovomab or placebo. The relationship of time-to-relapse, survival postrelapse, and overall survival was analyzed. One hundred forty-five patients in the intent-to-treat population and the hypothesis generating subset of 67 patients (debulked to < or =2 cm, CA125 < or =65 U/mL before cycle 3, normal CA125 and no evidence of disease postchemotherapy) previously reported were evaluated for long-term outcomes. Patterns of relapse and survival were consistent in both groups for the intent-to-treat population. Median survival time was 57.5 months for oregovomab and 48.6 months for placebo with an adjusted hazard ratio of 0.72 (95% confidence interval, 0.41-1.25). Median survival has not been reached in the hypothesis generating subset of patients receiving oregovomab. Cox multivariate regression analysis identified velocity of CA125 rise at relapse to be a highly statistically significant predictor of postrelapse outcome (P = 0.006). Although time-to-relapse may be a useful surrogate of survival in ovarian cancer immunotherapy studies, 5 years of follow-up has proved insufficient to permit a definitive survival analysis and it has been extended in ongoing phase III studies of oregovomab. Velocity of CA125 rise at relapse is a highly significant predictor of survival after relapse.

Peptides have been designed to be T cell tolerogenic for the principal allergens of the cat. These have been administered in several dosage programs to cat-sensitive patients in multicenter blinded st

This prospective, open-label, pilot phase 2 study examined the clinical and immunologic effects of oregovomab (OvaRex) in heavily pretreated patients with recurrent ovarian cancer (OC). Thirteen women were administered intravenous oregovomab (2 mg) at weeks 0, 2, 4, 8, and 12, followed by quarterly doses for up to 2 years or disease progression. Concomitant chemotherapy was not permitted. Eligibility criteria included recurrence after one or more platinum-based chemotherapy regimens, CA125 >35 U/mL, evaluable or measurable disease. Tumor burden was evaluated by physical or radiologic methods pretreatment, weeks 12, 24, and every 24 weeks thereafter. Immune responses, including antibodies and T cells to oregovomab and CA125, were demonstrated in over half the patients. Stabilization of disease and survival >2 years was observed in 3 of 13 patients and coincided with robust immune responses. Shrinkage of marker lesions was not observed; however, four patients showed decreases in CA125 levels. Treatment was well tolerated without serious adverse events or discontinuations due to therapy. This pilot study supports immunologic activity and safety of oregovomab in recurrent OC. Further study of this agent in the consolidation and adjuvant setting is ongoing to establish its clinical utility.

Despite advances in understanding and treatment, ovarian cancer remains a major cause of cancer mortality worldwide. Debulking surgery and paclitaxel/carboplatin chemotherapy induce good initial responses in most patients, although most cases of advanced disease are not controlled. Monoclonal antibodies hold promise as a potential incremental advance for the treatment of the disease. Antibodies can be used to stimulate the immune response, target tumor-specific receptors to induce antibody-dependent cellular cytotoxicity or interfere with biologic pathways. They can also be used to deliver therapeutic radioisotopes to malignant cells. Oregovomab is in Phase III clinical trials as a consolidation treatment post front-line therapy to trigger tumor-specific cellular immunity. Bevacizumab, which blocks vascular endothelial growth factor, will be entering Phase III as an adjuvant to front-line chemotherapy with a direct effect on angiogenesis. Additional immunostimulating, immune counter-regulatory and receptor-targeting approaches are also reviewed. The family of epidermal growth factor receptors including epidermal growth factor receptor 1 (HER-1) and 2 (HER-2) are both expressed in ovarian cancer and are the subject of ongoing research and development. The recent disappointing results with 90-yttrium-labeled anti-HMFG by single intraperitoneal administration have left the radiopharmaceutical field without a Phase III candidate. Identification of novel targets may advance this therapeutic area in the future. The rapid advances in the fields of immunoregulation and tumor biology should permit an accelerated introduction of antibodies for the treatment of ovarian cancer. These antibodies could complement novel small molecules that are also in development.

Background: BrevaRex w mAb-AR20.5 is a murine anti-MUC1 monoclonal antibody generated to induce MUC1 antigen-specific immune responses through the formation of immune complexes with circulating MUC1 and/or MUC1-expressing tumor cells that may target these immune complexes (IC) to receptors on dendritic cells (DCs). Patients and methods: A phase I study focusing on safety and immunology evaluated 1, 2 and 4-mg doses. Seventeen patients with MUC1-positive cancers received intravenous infusions of the antibody over 30 min on weeks 1, 3, 5, 9, 13 and 17 of treatment. Results: mAb-AR20.5 was well-tolerated, not associated with dose-limiting toxicity, and did not induce hypersensitivity reactions. Overall, five of 15 evaluable patients developed human anti-mouse antibodies (HAMA), five developed anti-idiotypic antibodies (Ab2) and seven developed anti-MUC1 antibodies. Immune responses were most prominent in the 2-mg dose cohort for all parameters tested, and treatment-emergent MUC1-specific T-cell responses were detected in five of 10 evaluable patients treated with mAb-AR20.5. Conclusions: The injection of a murine antibody to MUC1 induces MUC1-specific immune responses in advanced cancer patients. Anti-MUC1 antibody increases correlated with decrease or stabilization of CA15.3 levels (P = 0.03). The 2-mg dose of mAb-AR20.5 showed strongest biological activity, and will be evaluated in future efficacy trials.

Purpose To assess oregovomab as consolidation treatment of advanced ovarian cancer and refine the immunotherapeutic strategy for subsequent study. Patients and Methods Patients with stage III/IV ovarian cancer who had a complete clinical response to primary treatment were randomly assigned to oregovomab or placebo administered at weeks 0, 4, and 8, and every 12 weeks up to 2 years or until recurrence. The primary end-point was time to relapse (TTR). Results One hundred forty-five patients were treated with oregovomab (n = 73) or placebo (n = 72). For the population overall, median TTR was not different between treatments at 13.3 months for oregovomab and 10.3 months for placebo (P = .71). Immune responses were induced in most actively treated patients. This was associated with prolonged TTR. Quality of life was not adversely impacted by treatment. Adverse events were reported with similar frequency in oregovomab and placebo groups, indicating a benign safety profile. A long-term survival follow-up is ongoing. Cox analysis of relapse data identified significant factors: performance status, CA-125 before third cycle, and baseline CA-125. Further evaluation identified a subpopulation with favorable prognostic indicators designated as the successful front-line therapy (SFLT) population. For the SFLT population, TTR was 24.0 months in the oregovomab group compared with 10.8 months for placebo (unadjusted hazard ratio of 0.543 [95% CI, 0.287 to 1.025]), a hypothesis-generating observation. Conclusion Consolidation therapy with oregovomab did not significantly improve TTR overall. A set of confirmatory phase III studies has been initiated to determine whether the SFLT population derives benefit from oregovomab treatment.

The role of antibodies as therapeutic cancer vaccines includes two distinct approaches, which are summarised in this review, namely anti-idiotypic vaccines and antigen-antibody complex therapies. Bispecific antibodies directed against T cells or antigen-presenting cells are also referenced. The report focuses on theoretical issues, laboratory data on the mechanism of action, examples of humoral and cellular immune induction, and novel therapeutic advances in vaccine development. The biology of antigen processing and recent advances in the field of dendritic cell biology are critical to understanding the potent immune response induction. Future directions include combination therapies to manipulate immune regulatory mechanisms and to enhance clinical effects. Additional applications of antibodies targeting costimulatory or regulatory receptors on antigen-presenting cells and T cells, neutralising immune suppressive cytokines, and depleting T regulatory cells hold promise for future mono- and particularly combination therapies.

Objective: We evaluated the therapeutic efficiency of the murine monoclonal antibody-B43.13 in the treatment of patients with recurrent ovarian cancer. Study Design: This was a retrospective study of immune responses and survival in 44 patients who were treated with technetium 99m-labeled monoclonal antibody-B43.13, a murine monoclonal antibody that is directed against the tumor-associated antigen CA125. Most patients were pretreated heavily. Biologic activity was quantified by the assay of immune responses to the human anti-murine antibodies against the monoclonal antibody-B43.13 variable region (Ab 2 ) and antibodies that target the CA 125 antigen itself (anti-CA 125 antibody). Results: More than one half of patients (56.8%) survived for >12 months after the first dose of monoclonal antibody B43.13; 34.1% of the patients survived >24 months. To date, 6 of the 44 patients are alive, with survival times of 4 to 7.5 years after the start of the antibody treatment. More than 60% of the evaluable patients met predefined criteria for robust, treatment-emergent human anti-murine antibodies and Ab 2 responses, and these responses were associated with improved survival rates. Median survival time increased approximately 3-fold for human anti-murine antibody responders (22.6 months) versus nonresponders (7.2 months; P 2 responders (18.3 months) versus nonresponders (9.3 months). No serious drug-associated adverse events were reported. Conclusion: The associations between multiple types of immune response and improved clinical outcomes suggest that monoclonal antibody-B43.13 should be further evaluated for potential use as an immunotherapy for CA125-expressing malignancies. (Am J Obstet Gynecol 2003;189:28-36.)

More than 2,000 patients have been dosed in the clinical development programs for Allervax Cat and Ragweed products in North America, Europe and Japan. Two peptides derived from Fel d 1 and three peptides derived from Amb a 1 were selected for clinical development following T cell epitope mapping of these major allergens. Clinical activity has been demonstrated in several dose regimens containing 75 and 750 microg of each component peptide given in 4-6 doses over 2-4 weeks. Greater activity has been seen with higher doses. Immediate hypersensitivity to treatment peptides is rarely seen and can be avoided through patient screening. A putative pathway resulting in histamine-mediated but IgE-independent allergic symptoms, similar in nature and severity to natural allergen exposure, has been identified in association with treatment. These manifestations are more pronounced in cat than ragweed allergy and are consistent with the respective diseases. When desired, the symptoms may be ameliorated with administration of H1 blockers prior to symptom appearance. The seasonal rise in allergen-specific IgE is blunted in association with therapy. Antigen-specific antibody levels (IgE and IgG), T cell primary proliferation and immediate skin test sensitivity will be followed in longer-term studies.

Prostate cancer (PCa) is the second leading cause of cancer deaths among men in the United States. The prostate-specific antigen (PSA), often found at high levels in the serum of PCa patients, has been used as a marker for PCa detection and as a target of immunotherapy. The murine IgG1 monoclonal antibody AR47.47, specific for human PSA, has been shown to enhance antigen presentation by human dendritic cells and induce both CD4 and CD8 T-cell activation when complexed with PSA. In this study, we explored the properties of a novel mouse/human chimeric anti-PSA IgE containing the variable regions of AR47.47 as a potential therapy for PCa. Our goal is to take advantage of the unique properties of the IgE molecule in order to trigger immune activation against PCa. The properly assembled and secreted anti-PSA IgE binds the antigen and the Fc epsilon RI (FcεRI) as demonstrated by ELISA and flow cytometry, respectively. This novel IgE antibody is capable of triggering effector cell degranulation in vitro as determined by the release of β-hexosaminidase from rat basophil leukemic effector cells that express human FcεRI (RBL SX-38). Furthermore, the IgE triggered degranulation in vivo in human FcεRIα transgenic mice using the passive cutaneous anaphylaxis assay. Degranulation was only observed when the IgE was artificially cross-linked, but not in the presence of the natural soluble antigen, suggesting that such an interaction will not trigger systemic anaphylaxis in patients. Importantly, when incubated in vitro with human dendritic cells the anti-PSA IgE complexed with the antigen (PSA) triggered autologous CD4 and CD8 T-cell activation, suggesting enhancement of antigen presentation. Immune activation was also observed in vivo where a prophylactic vaccination with the anti-PSA IgE complexed to PSA significantly prolonged the survival of human FcεRIα transgenic mice challenged with PSA-expressing tumors, under conditions in which its chimeric mouse/human anti-PSA IgG1 counterpart failed to confer protection. Our results provide initial proof-of principle that the anti-PSA IgE can stimulate immune activation against tumor cells expressing PSA, and further studies on the anti-tumor activity of this antibody are warranted. These studies belong to the new field of AllergoOncology that aims to reveal the function of IgE-mediated immune responses against cancer and develop novel IgE-based cancer therapies. Citation Format: Tracy R. Daniels-Wells, Gustavo Helguera, Richard K. Leuchter, Rafaela Quintero, Maggie Kozman, Jose A. Rodríguez, Elizabeth Ortiz-Sánchez, Otoniel Martínez-Maza, Birgit C. Schultes, Christopher F. Nicodemus, Manuel L. Penichet. IgE-mediated immune activation targeting the prostate specific antigen: a potential prostate cancer therapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2848. doi:10.1158/1538-7445.AM2013-2848

A potent adjuvant is the key for a successful vaccine against tumor antigens. We evaluated the adjuvant effect of a TLR3 agonist, Ampligen® on the growth of breast cancer in a transgenic mouse model. Ampligen® [rintatolimod; poly(I)·poly(C12,U)] is a synthetic mismatched double strand RNA that specifically stimulates TLR3 (Hemispherx Biopharma, Philadelphia, PA). A neu-tg mice [strain name, FVB/N-TgN (MMTVneu) 202Mul] over-expressing both neu and IGFBP-2 tumor associated antigens (Park KH et al CR 2008) were used for this study. Three IGFBP2 peptides were used as immunogen. The mice were vaccinated with the peptides and Ampligen® three times, 2 weeks apart, with PBS, peptides alone, and Ampligen® alone as controls. Syngeneic MMC tumor cells were injected into the mice two weeks after the last vaccine, and the growth of tumors was monitored afterwards. Three other immune modulators (GM-CSF, TLR7 agonist Imiquimod and TLR9 agonist CpG ODN 2395) were also used to evaluate the efficacy of Ampligen® and combination adjuvant approaches. Our results indicate that peptides alone did not mediate an anti-tumor effect. Although Ampligen® alone at high concentration (100ug) had a weak anti-tumor effect as compared to the control with 23% tumor inhibition, vaccination with IGFBP2 antigen and Ampligen® remarkably inhibited tumor growth by 60%. A dose response of Ampligen® was observed with 20ug as the optimal dose. The analysis of the levels of multiplex cytokines (IL-12p70, IL-1a, IL-1b, IL-2, IL-5, IL-10, IL-17, IFNg and TNFa) in serum two days after last vaccine showed that the level of IL-12p70 was increased in peptides/Ampligen® treated mice as compared to control (5.9±0.9 vs. 3.1±0.8 pg/ml;n=5; p=0.041) or other adjuvants. The serum levels of other cytokines were not statistically different. We compared the adjuvant effect of Ampligen® with GM-CSF, Imiquimod and ODN 2395. Besides Imiquimod, all these adjuvants significantly inhibited tumor growth as compared with peptides alone (p Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 748. doi:10.1158/1538-7445.AM2011-748

5507 Background: Translating cancer specific immune stimulation into clinical benefit is a challenge. This ph III study tested the hypothesis that oregovomab (o) mono-immunotherapy IT following fro...

To the Editor: In their article, Sabbatini et al. ([1][1]) describe the phase I data of abagovomab, a murine anti-idiotype antibody to the CA125-specific monoclonal antibody OC125. In their Introduction, they compare abagovomab's mechanism of action to oregovomab's, a murine Ab1 antibody to CA125.

3024 Background: Chemotherapy (C) induced bone marrow suppression has been assumed to inhibit the generation of augmented immune responses. This has limited investigation of front-line C-IT in OC. Temporal relationship of IT administration relative to C has not been established. Oregovomab is a CA125 specific MAb in development as an OC adjuvant treatment to induce tumor specific immunity. Methods: Patients (pts) awaiting staging laparotomy for presumptive OC were consented to the study and contributed primary tumor samples. Qualifying pts were subsequently randomized to concurrent C-IT with antibody administered at cycles 1, 3, and 5 (Arm A) or 8 ± 2 days following cycles 1, 3, and 5 (Arm B) of standard C-P. Both arms received additional infusions of oregovomab every 12 weeks until progression; response to C-IT was assessed at 36 weeks. Results: Forty stage III/IV pts (18 Arm A; 22 Arm B) were randomized and dosed. More pts in Arm A (39%) were stage IV vs Arm B (14%) however 27% of Arm B pts had >2cm residual disease vs. 11% in Arm A. Complete clinical response (CR) to surgery and C-IT was achieved in 15 pts (83%) in Arm A and 17 pts (77%) in Arm B. For pts with = 2 cm residual disease, 88% in Arm A had = 65 U/mL CA125 prior to/at cycle 3, normalized CA125 and a CR post C-IT compared to 75% of pts in Arm B. Robust Ab2 antibody response (>100 ng/mL) was achieved in 94% of Arm A and 68% of Arm B pts. The immune response developed earlier in Arm A. After one injection of oregovomab, 31% of pts in Arm A vs. 0% in Arm B generated HAMA > 3000 ng/mL and Ab2 > 100 ng/mL (P=0.016 Fisher’s Exact Test). Such an early and vigorous response pattern has not been seen in previous oregovomab studies which have not included concomitant front-line C. There were no IT related serious adverse events. Conclusions: Contrary to expectations, concurrent C-P resulted in enhanced immune stimulation with oregovomab. Interestingly, concurrent infusion of oregovomab was more immunogenic than delayed infusion. Clinical activity was favorable and safety profiles were similar to that expected for C alone. Further randomized evaluation of front-line CP-oregovomab vs CP is warranted. [Table: see text]

The murine MAb-AR47.47 (IgG1κ) recognizes all circulating forms of PSA and targets the epitope EPEEFLT. In vitro studies showed that human and murine dendritic cells process PSA more efficiently in immune complexes (IC) with MAb-AR47.47. IC induced CD4+ and CD8+ IFN-γ producing T cells, whereas PSA alone or PSA combined with a non-specific antibody mainly stimulated CD4+ T cells. We have further investigated the activation of PSA-specific immune responses with IC in male PSA-transgenic mice, which express human PSA in the prostate. Mice were immunized with PSA and MAb-AR47.47 alone or IC consisting of MAb-AR47.47 and PSA at various concentrations. To investigate the need for foreign antibody in inducing immune responses, rabbit and goat polyclonal anti-PSA antibodies or MAb-AR47.47-ovalbumin were tested in parallel. The mice only generated a weak T helper 2 response to immunization with PSA alone. Robust T helper 1 and 2, CTL and antibody responses were induced in mice immunized with AR47.47-PSA IC. Interestingly, IC with PSA and the polyclonal goat or rabbit antibodies or MAb-AR47.47-ovalbumin induced stronger T helper cell responses to PSA, but resulted in weaker CTL induction relative to IC with MAb-AR47.47. This data indicates that AR47.47-PSA IC can prime B cells, T helper cells and CTL against the tumor antigen PSA in vivo in a setting where PSA is a self antigen.

5079 Background: Ov is a monoclonal antibody specific for CA125 currently in two phase III studies as a consolidation immunotherapy for OC. A five year outcome follow up for patients participating in the prior randomized phase II study used to design the current pivotal trials has been completed. An assessment of survival post relapse (SPR) as a function of identifiable risk factors, and implications for long term survival survey methodology were reviewed. Methods: OC patients with no evaluable disease post front-line chemotherapy were randomized to IV infusions of OV or Pbo Q4 wks × 3, then Q12 wks. At relapse, therapy was stopped and second-line Rx was initiated without restriction. All patients were surveyed quarterly for long term outcomes for a pre-specified 5 years from initial randomization. A Kaplan-Meier (KM) analysis of overall survival and Cox multivariate analysis of SPR was completed. Results: 145 randomized participants were followed, including 67 designated as the successful front-line (SFLT) subpopulation identified to have characteristics favorable for intervention with immunotherapy (basis of ongoing phase III program). At five years, 47% of Ov (n = 73) and 37% of Pbo (n = 72) patients were alive overall, and 56% of Ov (n = 34) and 32% of Pbo (n = 33) were alive in the SFLT population. KM estimates of median survival are 57.5 mo [44.5-non-estimable (ne)] for Ov and 48.6 mo [30.9-ne] for Pbo in the overall population and ne mo [50.5-ne] for Ov and 48.6 mo [24-ne] for Pbo (p = 0.11) in the subpopulation. For relapsed patients, improved survival post relapse was most associated (Cox regression p < 0.10) with lower CA125 velocity at relapse, treatment (Ov), and longer time to relapse. Conclusions: Survival data was consistent with previously reported time to relapse data in this study. For the SFLT, the 5 yr duration of survival survey and sample size were insufficient for a definitive outcome. However, results support the hypothesis that treatment with OvaRex may provide clinical benefit. The ongoing phase III studies will include a 10 year survival survey of 354 patients to definitively assess the impact of this treatment on long term survival. [Table: see text]

5035 Background: OV (oregovomab) is a MAb specific for CA125, currently in Phase III testing as an immunotherapy for consolidation of advanced OC. This study was designed to identify an optimal dos...