Immune Pharmacodynamic Responses of the Novel Cancer Immunotherapeutic Imprime PGG in Healthy Volunteers.

Imprime PGG (Imprime) is an i.v. administered, yeast ß-1,3/1,6 glucan in clinical development with checkpoint inhibitors. Imprime-mediated innate immune activation requires immune complex formation with naturally occurring IgG anti-ß glucan Abs (ABA). We administered Imprime to healthy human volunteers to assess the necessity of ABA for Imprime-mediated immunopharmacodynamic (IPD) changes. Imprime (4 mg/kg) was administered i.v. in single and multiple infusions. Subsets of subjects were premedicated with antihistamine and corticosteroid. Peripheral blood was measured before, during and after Imprime administration for IPD changes (e.g., ABA, circulating immune complexes, complement activation, complete blood counts, cytokine/chemokine, and gene expression changes). IPD changes were analyzed based on pretreatment serum ABA levels: low-ABA (<20 µg/ml), mid-ABA (≥20-50 µg/ml), and high-ABA (≥50 µg/ml). At the end of infusion, free serum ABA levels decreased, circulating immune complex levels increased, and complement activation was observed. At ∼1-4 h after end of infusion, increased expression of cytokines/chemokines, a 1.5-4-fold increase in neutrophil and monocyte counts and a broad activation of innate immune genes were observed. Low-ABA subjects typically showed minimal IPD changes except when ABA levels rose above 20 µg/ml after repeated Imprime dosing. Mild-to-moderate infusion-related reactions occurred in subjects with ABA ≥20 µg/ml. Premedications alleviated some of the infusion-related reactions, but also inhibited cytokine responses. In conclusion, ABA levels, being critical for Imprime-mediated immune activation may provide a plausible, mechanism-based biomarker to identify patients most likely to respond to Imprime-based anticancer immunotherapy.

A randomized, controlled trial evaluating the efficacy and safety of BTH1677 in combination with bevacizumab, carboplatin, and paclitaxel in first-line treatment of advanced non-small cell lung cancer.

BACKGROUND: BTH1677, a beta-glucan pathogen-associated molecular pattern molecule, drives an anti-cancer immune response in combination with oncology antibody therapies. This phase II study explored the efficacy, pharmacokinetics (PK), and safety of BTH1677 combined with bevacizumab/carboplatin/paclitaxel in patients with untreated advanced non-small cell lung cancer (NSCLC). METHODS: Patients were randomized to the BTH1677 arm (N = 61; intravenous [IV] BTH1677, 4 mg/kg, weekly; IV bevacizumab, 15 mg/kg, once each 3-week cycle [Q3W]; IV carboplatin, 6 mg/mL/min Calvert formula area-under-the-curve, Q3W; and IV paclitaxel, 200 mg/m2, Q3W) or Control arm (N = 31; bevacizumab/carboplatin/paclitaxel as above). Carboplatin/paclitaxel was discontinued after 4-6 cycles and patients who responded or remained stable received maintenance therapy with BTH1677/bevacizumab (BTH1677 arm) or bevacizumab (Control arm). Efficacy assessments, based on blinded central radiology review, included objective response rate (ORR; primary endpoint), disease control rate, duration of objective response, and progression-free survival. Overall survival and adverse events (AEs) were also assessed. RESULTS: ORR was higher in the BTH1677 vs Control arm but the difference between groups was not statistically significant (60.4% vs 43.5%; P = .2096). All other clinical endpoints also favored the BTH1677 arm but none statistically differed between arms. PK was consistent with previous studies. Although a higher incidence of Grade 3/4 AEs occurred in the BTH1677 vs Control arm (93.2% vs 66.7%), no unexpected AEs were observed. Serious AEs and discontinuations due to AEs were lower in the BTH1677 vs Control arm. CONCLUSIONS: Improvements in tumor assessments and survival were observed with BTH1677/bevacizumab/carboplatin/paclitaxel compared with control treatment in patients with advanced NSCLC. TRIAL REGISTRATION: ClinicalTrials.gov registration ID: NCT00874107 . Registered 2 April 2009. First participant was enrolled on 29 September 2009.

Combination anti-CD137 and anti-CD40 antibody therapy in murine myc-driven hematological cancers.

In order to stimulate antigen presentation and T cell activity against cancer, we treated three different tumor models in mice with the monoclonal antibodies anti-CD40 plus anti-CD137 (BiMab). In a subcutaneous transplantable MC38 colon cancer model, there was significant enhancement in the survival of mice following BiMab treatment. Anti-CD40 has shown considerable success against lymphoma in previous studies by other investigators, and we also showed in this study that, in a model of Eµ-Myc lymphoma, there was a statistically significant enhancement of survival of mice following BiMab treatment. Following the success of the BiMab treatment in the previous two models, we wished to determine if it would be successful in a mouse model of multiple myeloma. Firstly, we tested a transplantable model of disease in which multiple myeloma cells derived from Vk*MYC mice were injected intravenously. A minor proportion of anti-CD137 and BiMab treated mice experienced prolongation of life beyond 250 days. Then we tested the therapy in a spontaneously occurring multiple myeloma model, in Vk*MYC transgenic mice. The majority of mice treated survived longer than control mice, although statistical significance was not demonstrated.

CD40 agonists alter tumor stroma and show efficacy against pancreatic carcinoma in mice and humans.

Immunosuppressive tumor microenvironments can restrain antitumor immunity, particularly in pancreatic ductal adenocarcinoma (PDA). Because CD40 activation can reverse immune suppression and drive antitumor T cell responses, we tested the combination of an agonist CD40 antibody with gemcitabine chemotherapy in a small cohort of patients with surgically incurable PDA and observed tumor regressions in some patients. We reproduced this treatment effect in a genetically engineered mouse model of PDA and found unexpectedly that tumor regression required macrophages but not T cells or gemcitabine. CD40-activated macrophages rapidly infiltrated tumors, became tumoricidal, and facilitated the depletion of tumor stroma. Thus, cancer immune surveillance does not necessarily depend on therapy-induced T cells; rather, our findings demonstrate a CD40-dependent mechanism for targeting tumor stroma in the treatment of cancer.

Immune modulation with weekly dosing of an agonist CD40 antibody in a phase I study of patients with advanced solid tumors.

BACKGROUND: Single-dose infusion of the agonistic anti-CD40 monoclonal antibody (mAb) CP-870,893 accomplishes immune activation and clinical responses in patients with advanced cancers, but repeat dosing of this agent has not been reported. RESULTS: Twenty-seven patients were enrolled. The most common adverse event was transient, infusion-related cytokine release syndrome (CRS). Dose-limiting toxicities included grade 3 CRS and grade 3 urticaria; the maximum tolerated dose (MTD) was estimated to be 0.2 mg/kg. Seven patients (26%) had stable disease as the best clinical response; no partial or complete responses were observed. At the MTD, patient B lymphocytes exhibited persistently increased expression of costimulatory and adhesion molecules without resetting to baseline between doses. In 4 of 8 patients (50%) evaluated at the MTD, there were marked declines in total CD3(+) T lymphocytes, as well as CD4(+) and CD8(+) subsets. PATIENTS AND METHODS: Patients with advanced solid tumor malignancies received weekly intravenous infusions of CP-870,893 in four dose level cohorts. Safety and immune pharmacodynamics were assessed. CONCLUSIONS: Weekly infusions of the agonist CD40 antibody CP-870,893 were well-tolerated, but there was little clinical activity in advanced cancer patients. Correlative studies demonstrate chronic B cell activation and in some patients, T cell depletion. Longer dosing intervals may be desirable for optimal immune pharmacodynamics.

Clinical activity and immune modulation in cancer patients treated with CP-870,893, a novel CD40 agonist monoclonal antibody.

PURPOSE: The cell-surface molecule CD40 activates antigen-presenting cells and enhances immune responses. CD40 is also expressed by solid tumors, but its engagement results in apoptosis. CP-870,893, a fully human and selective CD40 agonist monoclonal antibody (mAb), was tested for safety in a phase I dose-escalation study. PATIENTS AND METHODS: Patients with advanced solid tumors received single doses of CP-870,893 intravenously. The primary objective was to determine safety and the maximum-tolerated dose (MTD). Secondary objectives included assessment of immune modulation and tumor response. RESULTS: Twenty-nine patients received CP-870,893 in doses from 0.01 to 0.3 mg/kg. Dose-limiting toxicity was observed in two of seven patients at the 0.3 mg/kg dose level (venous thromboembolism and grade 3 headache). MTD was estimated as 0.2 mg/kg. The most common adverse event was cytokine release syndrome (grade 1 to 2) which included chills, rigors, and fever. Transient laboratory abnormalities affecting lymphocytes, monocytes, platelets, D-dimer and liver function tests were observed 24 to 48 hours after infusion. Four patients with melanoma (14% of all patients and 27% of melanoma patients) had objective partial responses at restaging (day 43). CP-870,893 infusion resulted in transient depletion of CD19+ B cells in blood (93% depletion at the MTD for < 1 week). Among B cells remaining in blood, we found a dose-related upregulation of costimulatory molecules after treatment. CONCLUSION: The CD40 agonist mAb CP-870,893 was well tolerated and biologically active, and was associated with antitumor activity. Further studies of repeated doses of CP-870,893 alone and in combination with other antineoplastic agents are warranted.

High-dose cyclophosphamide with autologous lymphocyte-depleted peripheral blood stem cell (PBSC) support for treatment of refractory chronic autoimmune thrombocytopenia.

Patients with refractory chronic autoimmune thrombocytopenia (AITP) have a significant risk of morbidity and mortality related to hemorrhage. High-dose (HD) cytotoxic therapy may produce remissions but entails risks related to myelosuppression. Hematopoietic stem cell support with lymphocyte-depleted grafts may accelerate hematologic recovery and concomitantly reduce repopulation by autoreactive immunocytes. Fourteen patients with chronic AITP, in whom multiple prior therapies including corticosteroids, splenectomy, intravenous immunoglobulin, and various cytotoxic or immunomodulatory regimens had failed, were treated with HD cyclophosphamide (50 mg/kg/d) and autologous granulocyte colony-stimulating factor (G-CSF)-mobilized leukocytes depleted of lymphocytes by immunomagnetic CD34(+) selection. There were no significant adverse events related to G-CSF, intravenous device insertion, or leukapheresis. Treatment-related complications included transient hemorrhagic cystitis (1 patient), vaginal bleeding (2 patients), gastrointestinal bleeding (1 patient), epistaxis (1 patient), and antibiotic-responsive febrile neutropenia (all patients). The mean time to absolute neutrophil count (ANC) more than 500/mm(3) was 9 +/- 0.6 days. Eight patients experienced antibiotic-responsive gram-positive bacteremia. A median of 2 platelet transfusions was required for stem cell mobilization, intravenous catheter insertion, and apheresis and a median of 9 platelet transfusions was required during hematopoietic recovery. Six patients obtained durable complete responses (platelet counts > 100 000/mm(3) without other therapy) with maximum follow-up of 42 months. Two additional patients obtained durable partial responses (platelet counts significantly increased over baseline with reduced medication requirements and cessation of bleeding complications). This therapeutic approach is feasible for patients with severe chronic AITP, a substantial proportion of whom may obtain durable remissions. Larger controlled trials are recommended.