Targeting refractory/recurrent neuroblastoma and osteosarcoma with anti-CD3×anti-GD2 bispecific antibody armed T cells

BACKGROUND

The survival benefit observed in children with neuroblastoma (NB) and minimal residual disease who received treatment with anti-GD2 monoclonal antibodies prompted our investigation into the safety and potential clinical benefits of anti-CD3×anti-GD2 bispecific antibody (GD2Bi) armed T cells (GD2BATs). Preclinical studies demonstrated the high cytotoxicity of GD2BATs against GD2+cell lines, leading to the initiation of a phase I/II study in recurrent/refractory patients.

METHODS

The 3+3 dose escalation phase I study (NCT02173093) encompassed nine evaluable patients with NB (n=5), osteosarcoma (n=3), and desmoplastic small round cell tumors (n=1). Patients received twice-weekly infusions of GD2BATs at 40, 80, or 160×106 GD2BATs/kg/infusion complemented by daily interleukin-2 (300,000 IU/m2) and twice-weekly granulocyte macrophage colony-stimulating factor (250 µg/m2). The phase II segment focused on patients with NB at the dose 3 level of 160×106 GD2BATs/kg/infusion.

RESULTS

Of the 12 patients enrolled, 9 completed therapy in phase I with no dose-limiting toxicities. Mild and manageable cytokine release syndrome occurred in all patients, presenting as grade 2-3 fevers/chills, headaches, and occasional hypotension up to 72 hours after GD2BAT infusions. GD2-antibody-associated pain was minimal. Median overall survival (OS) for phase I and the limited phase II was 18.0 and 31.2 months, respectively, with a combined OS of 21.1 months. A phase I NB patient had a complete bone marrow response with overall stable disease. In phase II, 10 of 12 patients were evaluable: 1 achieved partial response, and 3 showed clinical benefit with prolonged stable disease. Over 50% of evaluable patients exhibited augmented immune responses to GD2+targets post-GD2BATs, as indicated by interferon-gamma (IFN-γ) EliSpots, Th1 cytokines, and/or chemokines.

CONCLUSIONS

This study demonstrated the safety of GD2BATs up to 160×106 cells/kg/infusion. Coupled with evidence of post-treatment endogenous immune responses, our findings support further investigation of GD2BATs in larger phase II clinical trials.

Phase I study targeting newly diagnosed grade 4 astrocytoma with bispecific antibody armed T cells (EGFR BATs) in combination with radiation and temozolomide

PURPOSE

The purpose of this study was to determine the safety, feasibility, and immunologic responses of treating grade 4 astrocytomas with multiple infusions of anti-CD3 x anti-EGFR bispecific antibody (EGFRBi) armed T cells (EGFR BATs) in combination with radiation and chemotherapy.

METHODS

This phase I study used a 3 + 3 dose escalation design to test the safety and feasibility of intravenously infused EGFR BATs in combination with radiation and temozolomide (TMZ) in patients with newly diagnosed grade 4 astrocytomas (AG4). After finding the feasible dose, an expansion cohort with unmethylated O6-methylguanine-DNA methyltransferase (MGMT) tumors received weekly EGFR BATs without TMZ.

RESULTS

The highest feasible dose was 80 × 109 EGFR BATs without dose-limiting toxicities (DLTs) in seven patients. We could not escalate the dose because of the limited T-cell expansion. There were no DLTs in the additional cohort of three patients with unmethylated MGMT tumors who received eight weekly infusions of EGFR BATs without TMZ. EGFR BATs infusions induced increases in glioma specific anti-tumor cytotoxicity by peripheral blood mononuclear cells (p < 0.03) and NK cell activity (p < 0.002) ex vivo, and increased serum concentrations of IFN-γ (p < 0.03), IL-2 (p < 0.007), and GM-CSF (p < 0.009).

CONCLUSION

Targeting AG4 with EGFR BATs at the maximum feasible dose of 80 × 109, with or without TMZ was safe and induced significant anti-tumor-specific immune responses. These results support further clinical trials to examine the efficacy of this adoptive cell therapy in patients with MGMT-unmethylated GBM.

CLINICALTRIALS

gov Identifier: NCT03344250.

Phase II Trial of Pembrolizumab and Anti-CD3 x Anti-HER2 Bispecific Antibody-Armed Activated T Cells in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

A phase II study was conducted to evaluate the safety and efficacy of the combination of HER2 bispecific antibody (HER2Bi)-armed activated T cells (HER2 BAT) and programmed death 1 inhibitor, pembrolizumab.

PATIENTS AND METHODS

Patients with metastatic castration-resistant prostate cancer (mCRPC) with 0 to 1 performance status and normal liver, kidney, and marrow function, pre- or post-docetaxel chemotherapy were eligible. Primary endpoint was 6-month progression-free survival (PFS). Peripheral blood mononuclear cells were obtained by a single apheresis, shipped to University of Virginia, activated with OKT3 and expanded for 14 days in IL2, harvested, and armed with HER2Bi and cryopreserved. HER2 BATs were infused twice weekly for 4 weeks and pembrolizumab was administered every 21 days for a maximum duration of 6 months starting 1 to 3 weeks prior to HER2 BATs infusion.

RESULTS

Fourteen patients were enrolled with a median age of 69 (range 57-82 years) and median PSA of 143.4 (range 8.2-4210 ng/dL). Two patients had peritoneal metastases, 1 had lymph node (LN) only metastases and 11 had bone metastases of which 7 had bone and LN metastases. All were pretreated with androgen receptor axis targeted agents and 7 (50%) had prior docetaxel chemotherapy. The toxicities were grade1-2 infusion reactions with fever, chills, headaches, nausea and/or myalgias. Primary endpoint of 6 month PFS was achieved in 5 of 14 patients (38.5%; 95% confidence interval, 19.5%-76.5%). Median PFS was 5 months and median survival was 31.6 months.

CONCLUSIONS

The safety and promising efficacy makes this combination worthy of future investigation in mCRPC.

Phase II clinical trial using anti-CD3 × anti-HER2 bispecific antibody armed activated T cells (HER2 BATs) consolidation therapy for HER2 negative (0-2+) metastatic breast cancer

Background

Metastatic human epidermal growth receptor II (HER2) negative breast cancer remains incurable. Our phase I study showed that anti-CD3 × anti-HER2 bispecific antibody armed activated T cells (HER2 BATs) may be effective against HER2-tumors. This phase II trial evaluates the efficacy and immune responses of HER2 BATs given to patients with metastatic HER2-estrogen and/or progesterone receptor positive (HR+) and triple negative breast cancer (TNBC) as immune consolidation after chemotherapy. The primary objective of this study was to increase the traditional median time to progression after failure of first-line therapy of 2–4 months with the secondary endpoints of increasing overall survival (OS) and immune responses.

Methods

HER2- metastatic breast cancer (MBC) patients received 3 weekly infusions of HER2 BATs and a boost after 12 weeks.

Results

This phase II study included 24 HER2-HR+ and 8 TNBC patients who received a mean of 3.75 and 2.4 lines of prior chemotherapy, respectively. Eight of 32 evaluable patients were stable at 4 months after the first infusion. There were no dose limiting toxicities. Tumor markers decreased in 13 of 23 (56.5%) patients who had tumor markers. The median OS was 13.1 (95% CI 8.6 to 17.4), 15.2 (95% CI 8.6 to 19.8), and 12.3 (95% CI 2.1 to 17.8) months for the entire group, HER2-HR+, and TNBC patients, respectively. Median OS for patients with chemotherapy-sensitive and chemotherapy-resistant disease after chemotherapy was 14.6 (9.6–21.8) and 8.6 (3.3–17.3) months, respectively. There were statistically significant increases in interferon-γ immunospots, Th₁ cytokines, Th₂ cytokines, and chemokines after HER2 BATs infusions.

Conclusions

In heavily pretreated HER2-patients, immune consolidation with HER2 BATs after chemotherapy appears to increase the proportion of patients who were stable at 4 months and the median OS for both groups as well as increased adaptive and innate antitumor responses. Future studies combining HER2 BATs with checkpoint inhibitors or other immunomodulators may improve clinical outcomes.

Clinical and immune responses to anti-CD3 x anti-EGFR bispecific antibody armed activated T cells (EGFR BATs) in pancreatic cancer patients

Purpose

This was a phase I/II adoptive T cell trial in 7 locally advanced and metastatic pancreatic cancer patients using 3–8 infusions of anti-CD3 x anti-EGFR bispecific antibody armed activated T cells (BATs) to determine safety, the maximum tolerated dose (MTD), immune responses, time to progression (TTP), and overall survival (OS). Study Design: T cells obtained by apheresis were expanded and armed with EGFRBi, cryopreserved for infusions. In a phase I dose escalation, five patients received three weekly infusions of 10–40 × 10⁹ BATs/infusion followed by a booster infusion 3 months later, and 2 patients received 8 infusions twice weekly for 4 weeks in a phase II. The trials were registered at http://www.clinicaltrials.gov, NCT01420874 and NCT02620865. Results: There were no dose-limiting toxicities (DLTs), and the targeted dose of 80 × 10⁹ BATs was met. The median TTP is 7 months, and the median OS is 31 months. Two patients had stable disease for 6.5 and 25+ months, and two patients developed complete responses (CRs) after restarting chemotherapy. Infusions of BATs induced anti-pancreatic cancer cytotoxicity, innate immune responses, cytokine responses (IL-12, IP-10), and shifts in CD4 and CD8 Vβ repertoire with enhanced cytoplasmic IFN-γ staining in the Vβ repertoire of the CD8 subset that suggest specific clonal TCR responses. Conclusions: Infusions of BATs are safe, induce endogenous adaptive anti-tumor responses, and may have a potential to improve overall survival.

Phase II clinical trial using anti-CD3 x anti-HER2 bispecific antibody armed activated T cells (HER2 BATs) for HER2-negative (0-2+) metastatic breast cancer

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Background: This study presents a phase II cell therapy trial in 32 women with metastatic or locally advanced HER2- breast cancer (BrCa) who received infusions of anti-CD3 x anti-HER2 bispecific antibody armed activated T cells (BATs). This phase II study (NCT 01022138) was conducted to determine if BATs infusions could improve time to progression (TTP) and overall survival (OS), as well as to confirm the toxicity profile of BATs. Methods: The phase II included 32 patients with a median of 4 lines of therapy (7 TNBC and 25 HR/PR+ HER2- patients) with an average age of 52.5 years (range 28-75 years). Twenty-one patients had ≥3 lines of prior therapy and 11 patients had 1-2 lines. Peripheral blood mononuclear cells (PBMC) were stimulated with anti-CD3 antibody and expanded in IL-2, armed with HER2Bi, and aliquoted for the clinical trial. Patients received oncologist’s choice of chemotherapy (4 cycles/4 months) followed by 3 infusions of BATs given once per week for 3 weeks and a boost given 12 weeks after the 3rd infusion. Results: Fifteen of 32 (ORR of 46.8%) who had received any cells had stable disease (SD) at 1 month after the last infusion, and 8 of 15 (25%) had SD > 4 months. For patients who completed 3 or 4 infusions (17-83 x 109 BATs), 8 of 31 patients had TTP > 4 months. One patient completed 2 infusions (17 x 109 BATs). There were no dose limiting toxicities (DLTs). Tumor markers decreased in 13 of 23 (56.5%) patients with evaluable markers. The median OS was 13.8, 16.5, and 12.4 months for all, ER/PR+, and TNBC, respectively. OS for all patients with chemosensitive (chemoS) and chemoresistant (chemoR) disease was 14.6 and 8.6 months (NS), respectively. OS for chemoS and chemoR disease in HER2- ER/PR+ patients was 16.5 and 8.6 months (NS), respectively. OS for chemoS and chemoR disease in TNBC patients was 12.4 and 22.6 months, respectively (NS). The median TTP for all, HER2- ER/PR+, and TNBC patients was 2.7, 2.9, and 1.4 months, respectively. Increases in serum IL-2 and IL-12 were associated with BATs infusions. Conclusions: Targeting HER2- tumors was safe. There were trends toward improved survival in patients who were HER2-/ER/PR+ TNBC, patients who were chemoS, was associated with increased TTP and OS in all groups, and was associated with decreased tumor markers in those who received 4 infusions. Immune studies showed evidence for induction of adaptive immunity directed at breast cancer antigens. Targeting metastatic HER2- BrCa with BATs shows promise. Clinical trial information: NCT 01022138.

Clinical and immune responses using anti-CD3 x anti-EGFR bispecific antibody armed T cells (BATs) for locally advanced or metastatic pancreatic cancer

4135

Background: Conventional chemotherapy (chemo) for locally advanced pancreatic cancer (LAPC) and metastatic pancreatic cancer (MPC) has dismal responses and poor survival rates. Arming activated T cells (ATC) with anti-CD3 x anti-EGFR bispecific antibody (BATs) makes every ATC into an EGFR-specific cytotoxic T cell that secretes cytokines, proliferates, and kills tumor. Methods: We report on 5 phase I (P1) and 15 phase II (P2) patients. In our phase I study, BATs were used to treat LAPC or MPC patients at Karmanos Cancer Institute (NCT0140874) in a dose escalation involving 3 weekly infusions of 1, 2, and 4 x 1010 BATs/infusion, followed by a booster infusion at 3 months (mos) for a total of up to 8 x 1010 BATs. No dose limiting toxicities were observed in the outpatient infusions. Fifteen patients treated on a phase II (NCT02620865) at KCI and (NCT03269526) at University of Virginia received biweekly infusions of 1010 BATs/infusion over 4 weeks for a total of 8 x 1010 EGFR BATs. Results: Four patients had stable disease (SD) for 6.1, 6.5, 5.3, and 36 mos. Two patients had complete responses (CR) when chemo was restarted after BATs. The median overall survival (OS) for 17 evaluable patients (3 of 4 infusions in the P1 and all 8 infusions in the P2) was 31 mos, and the median OS for all 20 patients (3 in the P2 who did not complete 8 infusions) is 14.5 mos (95% CI, 7.5-45.2 mos). Patient IT20104 had an apparent “pseudoprogression” after 3 BATs infusions, but achieved a CR after restarting capcitabine and is alive off therapy at 54 mos (24 mos after stopping capecitabine). Immune evaluations on the P1 patients show specific cytotoxicity to MiaPaCa-2 by peripheral blood mononuclear cells (PBMC) increased from 21% to 31% 2 weeks after the 3rd infusion, and IFN-γ EliSpots increased from < 20 to 1000 IFN-γ EliSpots/106 PBMC (p < 0.03). Patient IT 20121 (SD for 36 mos) increased IFN-γ EliSpots from 250 to 3200/106 PBMC after 8 infusions. Innate cytotoxicity responses in the P1 patients increased significantly after infusions (p < 0.04). Levels of IP-10 increased significantly (p < 0.04), and levels of IL-8 decreased but not significantly (p < 0.07). Conclusions: Infusions of BATs are safe and induce endogenous adaptive anti-tumor responses. Targeting PC with BATs may stabilize disease, leading to improved OS, as well as evidence that BATs infusions can induce anti-tumor activity and immunosensitize tumors to subsequent chemo. Clinical trial information: NCT014084,NCT03269526,NCT02620865.

Immune evaluation study of sipuleucel-T (Sip-T) in African-American and European-American men with castration-resistant prostate cancer

206

Background: Sipuleucel-T (Sip-T) is an autologous cellular immunotherapy indicated for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC) patients and targets the prostate antigen, prostatic acid phosphatase (PAP). In Phase 3 trials of Sip-T, there was a suggestion that AA men treated with Sip-T had enhanced OS benefit compared to the general population. This study was designed to evaluate the peripheral immune parameters in African American (AA) and European American (EA) prostate cancer patients receiving Sip-T treatment. Methods: Peripheral blood mononuclear cell and serum samples were evaluated for T- and B cell responses in 10 AA and 20 EA men with mCRPC. Antigen-specific T cell response was measured by IFN-γ Elispots, antigen-specific IgG and IgM responses to PA2024, PAP, PSMA, and PSA by ELISA, cytokine and chemokine levels by luminex and immune cell phenotyping by flow cytometry in the PBMC at baseline, 6-, and 10-week time points after completion of Sip-T treatment. Results: IFN-γ EliSpots were ≥ 2-fold higher when stimulated with PA2024 and PAP antigens in AA compared to EA patients post treatment. Humoral immune responses (IgM) to PA2024 and PAP was ≥ 100-fold higher at 6 and 10 weeks after completion of the 3rd infusion in both groups, however, there were no appreciable differences in antibody levels between AA and EA patients. Interestingly, there were ≥ 2-fold higher IgM titers for non-targeted PSA and PSMA at 6 and 10 weeks post treatment compared to baseline levels in both groups suggesting epitope spreading. Humoral responses (IgM) to PAP, PSA and PSMA at baseline were higher in AA patients compared to EA patients. The Th1 and Th2 cytokine and chemokine profiles showed no difference between AA and EA men except for inflammatory chemokine IL-8 which gradually decreased at 6 and 10 weeks from the baseline in AA patients compared to the transient decreases in EA patients. Conclusions: Our preliminary results are suggestive of slightly increased IFN-γ EliSpot responses in AA patients compared to EA patients. Both, AA and EA showed potent IgM antibody response to PA2024 and PAP antigens post treatment compared to the baseline levels. Clinical trial information: NCT01727154.

Preferential expression of functional IL-17R in glioma stem cells: potential role in self-renewal

Gliomas are the most common primary brain tumor and one of the most lethal solid tumors. Mechanistic studies into identification of novel biomarkers are needed to develop new therapeutic strategies for this deadly disease. The objective for this study was to explore the potential direct impact of IL-17−IL-17R interaction in gliomas. Immunohistochemistry and flow cytometry analysis of 12 tumor samples obtained from patients with high grade gliomas revealed that a considerable population (2–19%) of cells in all malignant gliomas expressed IL-17RA, with remarkable co-expression of the glioma stem cell (GSC) markers CD133, Nestin, and Sox2. IL-17 enhanced the self-renewal of GSCs as determined by proliferation and Matrigel^® colony assays. IL-17 also induced cytokine/chemokine (IL-6, IL-8, interferon-γ-inducible protein [IP-10], and monocyte chemoattractant protein-1 [MCP-1]) secretion in GSCs, which were differentially blocked by antibodies against IL-17R and IL-6R. Western blot analysis showed that IL-17 modulated the activity of signal transducer and activator of transcription 3 (STAT3), nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB), glycogen synthase kinase-3β (GSK-3β) and β-catenin in GSCs. While IL-17R-mediated secretion of IL-6 and IL-8 were significantly blocked by inhibitors of NF-κB and STAT3; NF-κB inhibitor was more potent than STAT3 inhibitor in blocking IL-17-induced MCP-1 secretion. Overall, our results suggest that IL-17–IL-17R interaction in GSCs induces an autocrine/paracrine cytokine feedback loop, which may provide an important signaling component for maintenance/self-renewal of GSCs via constitutive activation of both NF-κB and STAT3. The results also strongly implicate IL-17R as an important functional biomarker for therapeutic targeting of GSCs.

Targeted delivery of siRNA to activated T cells via transferrin-polyethylenimine (Tf-PEI) as a potential therapy of asthma

Asthma is a worldwide health problem. Activated T cells (ATCs) in the lung, particularly T helper 2 cells (Th2), are strongly associated with inducing airway inflammatory responses and chemoattraction of inflammatory cells in asthma. Small interfering RNA (siRNA) as a promising anti-sense molecule can specifically silence inflammation related genes in ATCs, however, lack of safe and efficient siRNA delivery systems limits the application of siRNA as a therapeutic molecule in asthma. Here, we designed a novel pulmonary delivery system of siRNA, transferrin-polyethylenimine (Tf-PEI), to selectively deliver siRNA to ATCs in the lung. Tf-PEI polyplexes demonstrated optimal physicochemical properties such as size, distribution, zeta-potential, and siRNA condensation efficiency. Moreover, in vitro studies showed significantly enhanced cellular uptake and gene knockdown mediated by Tf-PEI polyplexes in human primary ATCs. Biodistribution of polyplexes in a murine asthmatic model confirmed that Tf-PEI polyplexes can efficiently and selectively deliver siRNA to ATCs. In conclusion, the present work proves the feasibility to target ATCs in asthma via Tf receptor. This strategy could potentially be used to design an efficient siRNA delivery system for asthma therapy.

Microenvironment generated during EGFR targeted killing of pancreatic tumor cells by ATC inhibits myeloid-derived suppressor cells through COX2 and PGE2 dependent pathway

Background

Myeloid-derived suppressor cells (MDSCs) are one of the major components of the immune-suppressive network, play key roles in tumor progression and limit therapeutic responses. Recently, we reported that tumor spheres formed by breast cancer cell lines were visibly smaller in a Th₁ enriched microenvironment with significantly reduced differentiation of MDSC populations in 3D culture. In this study, we investigated the mechanism(s) of bispecific antibody armed ATC mediated inhibition of MDSC in the presence or absence of Th₁ microenvironment.

Methods

We used 3D co-culture model of peripheral blood mononuclear cells (PBMC) with pancreatic cancer cells MiaPaCa-2 [MiaE] and gemcitabine resistant MiaPaCa-GR [MiaM] cells to generate MDSC in the presence or absence of Th₁ cytokines and EGFRBi armed ATC (aATC).

Results

We show significantly decreased differentiation of MDSC (MiaE, p<0.005; MiaM, p<0.05) in the presence of aATC with or without Th₁ cytokines. MDSC recovered from control cultures (without aATC) showed potent ability to suppress T cell functions compared to those recovered from aATC containing co-cultures. Reduced accumulation of MDSC was accompanied by significantly lower levels of COX2 (p<0.0048), PGE₂ (p<0.03), and their downstream effector molecule Arginase-1 (p<0.01), and significantly higher levels of TNF-α, IL-12 and chemokines CCL3, CCL4, CCL5, CXCL9 and CXCL10 under aATC induced Th₁ cytokine enriched microenvironment.

Conclusions

These data suggest aATC can suppress MDSC differentiation and attenuation of their suppressive activity through down regulation of COX2, PGE₂ and ARG1 pathway that is potentiated in presence of Th₁ cytokines, suggesting that Th₁ enriching immunotherapy may be beneficial in pancreatic cancer treatment.

Pan-Bcl-2 inhibitor AT-101 enhances tumor cell killing by EGFR targeted T cells

Pancreatic cancer is a deadly disease and has the worst prognosis among almost all cancers and is in dire need of new and improved therapeutic strategies. Conditioning of tumor cells with chemotherapeutic drug has been shown to enhance the anti-tumor effects of cancer vaccines and adoptive cell therapy. In this study, we investigated the immunomodulatory effects of pan-Bcl-2 inhibitor AT-101 on pancreatic cancer (PC) cell cytotoxicity by activated T cells (ATC). The effects of AT-101 on cytotoxicity, early apoptosis, and Granzyme B (GrzB) and IFN-γ signaling pathways were evaluated during EGFR bispecific antibody armed ATC (aATC)-mediated killing of L3.6pl and MiaPaCa-2 PC cells pre-sensitized with AT-101. We found that pretreatment of tumor cells with AT-101 enhanced susceptibility of L3.6pl and MiaPaCa-2 tumor cells to ATC and aATC-mediated cytotoxicity, which was in part mediated via enhanced release of cytolytic granule GrzB from ATC and aATC. AT-101-sensitized L3.6pl cells showed up-regulation of IFN-γ-mediated induction in the phosphorylation of Ser⁷²⁷-Stat1 (pS⁷²⁷-Stat1), and IFN-γ induced dephosphorylation of phospho-Tyr⁷⁰⁵-Stat3 (pY⁷⁰⁵-Stat3). Priming (conditioning) of PC cells with AT-101 can significantly enhance the anti-tumor activity of EGFRBi armed ATC through increased IFN-γ induced activation of pS⁷²⁷-Stat1 and inhibition of pY⁷⁰⁵-Stat3 phosphorylation, and resulting in increased ratio of pro-apoptotic to anti-apoptotic proteins. Our results verify enhanced cytotoxicity after a novel chemotherapy conditioning strategy against PC that warrants further in vivo and clinical investigations.

Activated T cells from umbilical cord blood armed with anti-CD3 × anti-CD20 bispecific antibody mediate specific cytotoxicity against CD20+ targets with minimal allogeneic reactivity: a strategy for providing antitumor effects after cord blood transplants

BACKGROUND

In this study, we asked whether anti-CD3-activated T cells (ATCs) from cord blood (CB) could be expanded and targeted to solid tumors or hematologic malignancies for infusions after unrelated CB stem cell transplant and whether cord blood ATCs (CBATCs) could reduce alloresponsiveness.

STUDY DESIGN AND METHODS

CB mononuclear cells (MNCs) were activated with anti-CD3 (20 ng/mL) and expanded for 14 days in interleukin-2 (100 IU/mL). CBATCs were armed with anti-CD3 × anti-CD20 (CD20Bi) or anti-CD3 × anti-Her2 (Her2Bi) bispecific antibodies (CBaATCs) and tested for specific cytotoxicity, cytokine secretion, and alloresponsiveness.

RESULTS

Our results show the mean expansion of CBATCs to be 37-fold after 14 days of culture from either frozen (n=4) or fresh (n=4) CB units. Cytotoxicity was optimal when CBATCs were armed with 50 ng of CD20Bi/10(6) cells. Cytotoxicity peaked between Day 8 and Day 10 for both bispecific antibodies. At an effector-to-target ratio of 25:1, the mean cytotoxicities of CBATCs armed with Her2Bi or CD20Bi were 40% (n=4) and 30% (n=4), respectively. CBaATCs exhibited peak specific interferon-γ enzyme-linked immunosorbent spots on Day 10. CBATCs and CBaATCs suppressed responsiveness to alloantigens by 20% to 50% when compared with normal allogeneic peripheral blood MNC response.

CONCLUSION

We showed that armed CBATCs mediate specific cytotoxicity, secrete low levels of cytokines and chemokines, and demonstrate attenuated response to alloantigens.

Granular shear flow dynamics and forces: experiment and continuum theory

We analyze the main features of granular shear flow through experimental measurements in a Couette geometry and a comparison to a locally Newtonian, continuum model of granular flow. The model is based on earlier hydrodynamic models, adjusted to take into account the experimentally observed coupling between fluctuations in particle motion and mean-flow properties. Experimentally, the local velocity fluctuations are found to decrease more slowly with distance from the shear surface than the velocity. This can be explained by an effective viscosity that diverges more rapidly as the random-close-packing density is approached than is predicted by Enskog theory for dense hard-sphere systems. Experiment and theory are in good agreement, especially for the following key features of granular flow: The flow is confined to a small shear band, fluctuations decay approximately exponentially away from the sheared wall, and the shear stress is approximately independent of the shear velocity. The functional forms of the velocity and fluctuation profiles predicted by the model agree with the experimental results.