Two-year follow-up of lisocabtagene maraleucel in relapsed or refractory large B-cell lymphoma in TRANSCEND NHL 001

ABSTRACT

Lisocabtagene maraleucel (liso-cel) demonstrated significant efficacy with a manageable safety profile as third-line or later treatment for patients with relapsed or refractory (R/R) large B-cell lymphoma (LBCL) in the TRANSCEND NHL 001 study. Primary end points were adverse events (AEs), dose-limiting toxicities, and objective response rate (ORR) per independent review committee. Key secondary end points were complete response (CR) rate, duration of response (DOR), progression-free survival (PFS), and overall survival (OS). After 2-year follow-up, patients could enroll in a separate study assessing long-term (≤15 years) safety and OS. Liso-cel-treated patients (N = 270) had a median age of 63 years (range, 18-86 years) and a median of 3 prior lines (range, 1-8) of systemic therapy, and 181 of them (67%) had chemotherapy-refractory LBCL. Median follow-up was 19.9 months. In efficacy-evaluable patients (N = 257), the ORR was 73% and CR rate was 53%. The median (95% confidence interval) DOR, PFS, and OS were 23.1 (8.6 to not reached), 6.8 (3.3-12.7), and 27.3 months (16.2-45.6), respectively. Estimated 2-year DOR, PFS, and OS rates were 49.5%, 40.6%, and 50.5%, respectively. In the 90-day treatment-emergent period (N = 270), grade 3 to 4 cytokine release syndrome and neurological events occurred in 2% and 10% of patients, respectively. The most common grade ≥3 AEs in treatment-emergent and posttreatment-emergent periods, respectively, were neutropenia (60% and 7%) and anemia (37% and 6%). Liso-cel demonstrated durable remissions and a manageable safety profile with no new safety signals during the 2-year follow-up in patients with R/R LBCL. These trials were registered at www.ClinicalTrials.gov as #NCT02631044 and #NCT03435796.

Mosunetuzumab in combination with CHOP in previously untreated DLBCL: safety and efficacy results from a phase 2 study

Up to 40% of patients with diffuse large B-cell lymphoma (DLBCL) are refractory to or relapse after first-line therapy, highlighting the need for better treatments. Mosunetuzumab is a CD20 × CD3 bispecific antibody that engages and redirects T cells to eliminate malignant B cells. In this phase 2, open-label study (NCT03677141), 40 patients (52.5% with international prognostic index ≥3) with previously untreated DLBCL initiated 6 cycles of IV mosunetuzumab with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy. Mosunetuzumab was administered in cycle 1 as step-up doses to mitigate cytokine release syndrome [CRS], and a dose of 30 mg was given on day 1 of cycles 2-6. Efficacy end points included objective and complete response rates, as determined by the investigator, via positron emission tomography-computed tomography, using Lugano 2014 criteria (87.5% and 85.0%, respectively). At a median follow-up of 32.0 months, the estimated 2-year progression-free survival and event-free survival rates were 65.4% (95% confidence interval [CI], 49.5-81.4) and 60.4% (95% CI, 44.7-76.1), respectively. CRS occurred in 60.0% of patients; all events were grade 1 (45.0%) or grade 2 (15.0%) and occurred primarily in cycle 1. Mosunetuzumab-related grade ≥3 neurologic adverse events (AEs) potentially consistent with immune effector cell-associated neurotoxicity syndrome occurred in 1 patient (2.5%). Grade 5 AEs were reported in 2 patients. Neutropenia occurred in 70.0% of patients, mostly during cycle 1 and was of short duration. These findings demonstrate promising activity and a manageable safety profile for mosunetuzumab-CHOP and warrant further investigation of mosunetuzumab in first-line combination regimens for DLBCL.

Molecular disease monitoring in patients with relapsed/refractory B-cell non-Hodgkin lymphoma receiving anti-CD19 CAR T-cell therapy

7531

Background: Chimeric antigen receptor (CAR) T-cell therapy has improved the historically poor outcomes for relapsed and refractory (R/R) B-cell non-Hodgkin’s lymphoma (NHL). However, nearly 60% of patients will either fail to respond or relapse after CAR T-cell therapy. Currently, PET/CT scans are used to assess response. Cell-free circulating tumor DNA (ctDNA) is released by tumor cells into the peripheral blood and can be measured for minimal residual disease (MRD) assessment. Methods: In this retrospective, IRB approved pilot study, archived lymphoma tissues and ctDNA from peripheral blood samples on day 0, 14, 28, 56, 80, 180, and 365 after CAR T-cell infusion from 10 patients with R/R NHL were collected for next-generation sequencing (NGS) of clonal variable-diversity-joining (VDJ) rearrangements [Adaptive biotechnologies (Seattle, WA)]. Response was assessed by PET/CT on days 30, 60, 90, 180 and 365 and graded according to the Lugano 2014 criteria. The primary endpoint was to determine the feasibility of detecting ctDNA to monitor disease response after anti-CD19 CAR T-cells. The secondary endpoint was to compare the sensitivity/specificity of MRD assessment from ctDNA to PET/CT imaging. Results: Nine out of 10 patients with a trackable sequence [median age 69 (range: 56-76); 55.6% male; median LDH 224], were included in this study. Each received tisagenlecleucel CAR T-cell therapy after median two prior treatments (range: 2-4). 7/9 patients had R/R diffuse large B-cell lymphoma (DLBCL), and 2/9 had transformed follicular lymphoma. At a median follow up of 12.7 months (range: 1.5-30 months), four patients were alive. By day 90, three patients (33.3%) achieved a radiographic complete response (CR) whilst six patients (66.6%) had progressive disease (PD). MRD and radiographic response are outlined in the Table. Detectable MRD on day 14 or day 28 had 83% sensitivity and 100% specificity for radiographic progression at any time before one year. For patients with PD, the median (interquartile range) MRD at day 0, 14, and 28 were 17.31 (1.01, 96.84), 9.12 (0.30, 18.8), and 23.77 (8.01, 137.53) copies per milliliter (mL), respectively. For patients with detectable MRD at day 28, mOS and mPFS were 205 and 38 days, respectively. Conclusions: Our pilot study demonstrated that monitoring MRD was a sensitive and specific method to detect disease response and relapse. In addition, MRD can be monitored more frequently, thus allowing for earlier detection of relapse. MRD and PET/CT identified progressive disease (PD) or complete response (CR) by day 90 in nine patients (A-I) with R/R NHL post CAR T-cell infusion.[Table: see text]

CELESTIMO: A phase III trial evaluating the efficacy and safety of mosunetuzumab plus lenalidomide versus rituximab plus lenalidomide in patients with relapsed or refractory follicular lymphoma who have received ≥ 1 line of systemic therapy

TPS7588

Background: Despite significant progress with first-line immunochemotherapy, most patients with follicular lymphoma (FL) will eventually relapse with increasing refractoriness and decreasing duration of response to subsequent therapy lines (Rivas-Delgado et al. 2019). Mosunetuzumab (M) is a CD20xCD3 bispecific antibody that engages and redirects T-cells to eliminate malignant B cells (Sun et al. 2015). In an ongoing, pivotal Phase I/II trial of M monotherapy, patients with relapsed/refractory (R/R) FL who have received ≥2 prior treatment lines achieve deep and durable responses (NCT02500407; Budde et al. ASH 2021). Preliminary data from a Phase Ib study have suggested favorable safety and promising activity of M in combination with lenalidomide (Len), a potent immunomodulatory agent that has shown additive/synergistic activity with an anti-CD20 antibody in R/R indolent lymphoma (Leonard et al. 2019), in patients with R/R FL who have received ≥1 prior therapy (NCT04246086; Morschhauser et al. ASH 2021). The chemotherapy-free M-Len combination may represent a promising outpatient therapy option for future management of patients with R/R FL. The randomized, multicenter Phase III study has been initiated. Methods: CELESTIMO (NCT04712097) is a randomized, multicenter, open-label Phase III study evaluating the efficacy and safety of M-Len versus rituximab plus Len (R-Len) in patients with previously treated R/R FL. Patients must have histologically documented CD20+ FL (Grades 1–3a) requiring systemic therapy and have received ≥1 prior line of systemic therapy. Patients are randomized (1:1) to receive M-Len (M intravenously [IV] on Days [D] 1, 8 and 15 of Cycle [C] 1 [21-day cycle] and D1 of C2–12 [28-day cycles], plus Len orally [PO] on D1–21 of C2–12) or R-Len (R IV on D1, 8, 15 and 22 of C1 then on D1 of C3, 5, 7, 9, and 11, plus Len PO on D1–21 of C1–12 [all 28-day cycles]), and stratified by disease progression within 24 months of initial treatment (yes/no), number of prior lines of therapy (1 versus ≥2), and refractoriness to anti-CD20 therapy (refractory/non-refractory). The primary endpoint is progression-free survival (PFS) assessed by independent review committee; secondary endpoints include investigator-assessed PFS, complete and objective response, overall survival, and safety. Biomarkers predictive of response to M-Len and R-Len will also be investigated as exploratory endpoints. The study started recruitment in 2021 and plans to enroll ̃400 patients from approximately 16 countries and 150 sites globally. Clinical trial information: NCT04712097.

Highly aminated iron oxide nanoworms for simultaneous manufacturing and labeling of chimeric antigen receptor T cells

Cell based therapies including chimeric antigen receptor (CAR) T cells are promising for treating leukemias and solid cancers. At the same time, there is interest in enhancing the functionality of these cells via surface decoration with nanoparticles (backpacking). Magnetic nanoparticle cell labeling is of particular interest due to opportunities for magnetic separation, in vivo manipulation, drug delivery and magnetic resonance imaging (MRI). While modification of T cells with magnetic nanoparticles (MNPs) was explored before, we questioned whether MNPs are compatible with CAR-T cells when introduced during the manufacturing process. We chose highly aminated 120 nm crosslinked iron oxide nanoworms (CLIO NWs, ~36,000 amines per NW) that could efficiently label different adherent cell lines and we used CD123 CAR-T cells as the labeling model. The CD123 CAR-T cells were produced in the presence of CLIO NWs, CLIO NWs plus protamine sulfate (PS), or PS only. The transduction efficiency of lentiviral CD123 CAR with only NWs was ~23% lower than NW+PS and PS groups (~33% and 35%, respectively). The cell viability from these three transduction conditions was not reduced within CAR-T cell groups, though lower compared to non-transduced T cells (mock T). Use of CLIO NWs instead of, or together with cationic protamine sulfate for enhancement of lentiviral transduction resulted in comparable levels of CAR expression and viability but decreased the proportion of CD8+ cells and increased the proportion of CD4+ cells. CD123 CAR-T transduced in the presence of CLIO NWs, CLIO NWs plus PS, or PS only, showed similar level of cytotoxicity against leukemic cell lines. Furthermore, fluorescence microscopy imaging demonstrated that CD123 CAR-T cells labeled with CLIO NW formed rosettes with CD123+ leukemic cells as the non-labeled CAR-T cells, indicating that the CAR-T targeting to tumor cells has maintained after CLIO NW labeling. The in vivo trafficking of the NW labeled CAR-T cells showed the accumulation of CAR-T labeled with NWs primarily in the bone marrow and spleen. CAR-T cells can be magnetically labeled during their production while maintaining functionality using the positively charged iron oxide NWs, which enable the in vivo biodistribution and tracking of CAR-T cells.

Combined haploidentical and cord blood transplantation for refractory severe aplastic anaemia and hypoplastic myelodysplastic syndrome

Umbilical cord blood (UCB) transplantation is a potentially curative treatment for patients with refractory severe aplastic anaemia (SAA), but has historically been associated with delayed engraftment and high graft failure and mortality rates. We conducted a prospective phase 2 trial to assess outcome of an allogeneic transplant regimen that co-infused a single UCB unit with CD34⁺ -selected cells from a haploidentical relative. Among 29 SAA patients [including 10 evolved to myelodysplastic syndrome (MDS)] who underwent the haplo cord transplantation (median age 20 years), 97% had neutrophil recovery (median 10 days), and 93% had platelet recovery (median 32 days). Early myeloid engraftment was from the haplo donor and was gradually replaced by durable engraftment from UCB in most patients. The cumulative incidences of grade II-IV acute and chronic graft-versus-host disease (GVHD) were 21% and 41%, respectively. With a median follow-up of 7·5 years, overall survival was 83% and GVHD/relapse-free survival was 69%. Patient- and transplant-related factors had no impact on engraftment and survival although transplants with haplo-versus-cord killer-cell immunoglobulin-like receptor (KIR) ligand incompatibility had delayed cord engraftment. Our study shows haplo cord transplantation is associated with excellent engraftment and long-term outcome, providing an alternative option for patients with refractory SAA and hypoplastic MDS who lack human leucocyte antigen (HLA)-matched donors.

Lisocabtagene maraleucel for patients with relapsed or refractory large B-cell lymphomas (TRANSCEND NHL 001): a multicentre seamless design study

BACKGROUND

Lisocabtagene maraleucel (liso-cel) is an autologous, CD19-directed, chimeric antigen receptor (CAR) T-cell product. We aimed to assess the activity and safety of liso-cel in patients with relapsed or refractory large B-cell lymphomas.

METHODS

We did a seamless design study at 14 cancer centres in the USA. We enrolled adult patients (aged ≥18 years) with relapsed or refractory large B-cell lymphomas. Eligible histological subgroups included diffuse large B-cell lymphoma, high-grade B-cell lymphoma with rearrangements of MYC and either BCL2, BCL6, or both (double-hit or triple-hit lymphoma), diffuse large B-cell lymphoma transformed from any indolent lymphoma, primary mediastinal B-cell lymphoma, and follicular lymphoma grade 3B. Patients were assigned to one of three target dose levels of liso-cel as they were sequentially tested in the trial (50 × 10⁶ CAR⁺ T cells [one or two doses], 100 × 10⁶ CAR⁺ T cells, and 150 × 10⁶ CAR⁺ T cells), which were administered as a sequential infusion of two components (CD8⁺ and CD4⁺ CAR⁺ T cells) at equal target doses. Primary endpoints were adverse events, dose-limiting toxicities, and the objective response rate (assessed per Lugano criteria); endpoints were assessed by an independent review committee in the efficacy-evaluable set (comprising all patients who had confirmed PET-positive disease and received at least one dose of liso-cel). This trial is registered with ClinicalTrials.gov, NCT02631044.

FINDINGS

Between Jan 11, 2016, and July 5, 2019, 344 patients underwent leukapheresis for manufacture of CAR⁺ T cells (liso-cel), of whom 269 patients received at least one dose of liso-cel. Patients had received a median of three (range 1-8) previous lines of systemic treatment, with 260 (97%) patients having had at least two lines. 112 (42%) patients were aged 65 years or older, 181 (67%) had chemotherapy-refractory disease, and seven (3%) had secondary CNS involvement. Median follow-up for overall survival for all 344 patients who had leukapheresis was 18·8 months (95% CI 15·0-19·3). Overall safety and activity of liso-cel did not differ by dose level. The recommended target dose was 100 × 10⁶ CAR⁺ T cells (50 × 10⁶ CD8⁺ and 50 × 10⁶ CD4⁺ CAR⁺ T cells). Of 256 patients included in the efficacy-evaluable set, an objective response was achieved by 186 (73%, 95% CI 66·8-78·0) patients and a complete response by 136 (53%, 46·8-59·4). The most common grade 3 or worse adverse events were neutropenia in 161 (60%) patients, anaemia in 101 (37%), and thrombocytopenia in 72 (27%). Cytokine release syndrome and neurological events occurred in 113 (42%) and 80 (30%) patients, respectively; grade 3 or worse cytokine release syndrome and neurological events occurred in six (2%) and 27 (10%) patients, respectively. Nine (6%) patients had a dose-limiting toxicity, including one patient who died from diffuse alveolar damage following a dose of 50 × 10⁶ CAR⁺ T cells.

INTERPRETATION

Use of liso-cel resulted in a high objective response rate, with a low incidence of grade 3 or worse cytokine release syndrome and neurological events in patients with relapsed or refractory large B-cell lymphomas, including those with diverse histological subtypes and high-risk features. Liso-cel is under further evaluation at first relapse in large B-cell lymphomas and as a treatment for other relapsed or refractory B-cell malignancies.

FUNDING

Juno Therapeutics, a Bristol-Myers Squibb Company.

A pilot trial of complement inhibition using eculizumab to overcome platelet transfusion refractoriness in human leukocyte antigen allo-immunized patients

Heavily transfused patients frequently develop human leukocyte antigen (HLA) allo-immunization resulting in platelet transfusion refractoriness and a high risk for life-threatening thrombocytopenia. Data suggest complement activation leading to the destruction of platelets bound by HLA allo-antibodies may play a pathophysiologic role in platelet refractoriness. Here we conducted a pilot trial to investigate the use of eculizumab, a monoclonal antibody that binds and inhibits C5 complement, to treat platelet transfusion refractoriness in allo-immunized patients with severe thrombocytopenia. A single eculizumab infusion was administered to 10 eligible patients, with four (40%) patients overcoming platelet refractories assessed measuring the corrected platelet count increment (CCI) 10-60 min and 18-24 h post transfusion. Responding patients had a reduction in the requirement for subsequent platelet transfusions and had higher post-transfusion platelet increments for 14 days following eculizumab administration. Remarkably, three of the four responders met CCI criteria for response despite receiving HLA-incompatible platelets. Our results suggest that eculizumab has the ability to overcome platelet transfusion refractoriness in patients with broad HLA allo-immunization. This study establishes proof of principle that complement inhibition can treat platelet transfusion refractoriness, laying the foundation for a large multicentre trial to assess the overall efficacy of this approach (ClinicalTrials.gov, identifier: NCT02298933).

Letermovir prophylaxis through day 100 post transplant is safe and effective compared with alternative CMV prophylaxis strategies following adult cord blood and haploidentical cord blood transplantation

We compared CMV outcomes of three prophylactic approaches used for CBT and haploidentical cord transplants from December 2009 through 2018: letermovir (n = 32) through day 100 post transplant, "valacyclovir day 100" (valacyclovir 2 g orally three times daily through day 100) (n = 60), and "valacyclovir hospital discharge" (valacyclovir 2 g orally three times daily through hospital discharge then acyclovir 800 mg twice daily) (n = 41). Through day 100, none in the letermovir group, six (10%) in the "valacyclovir day 100," and nine (22%) in the "valacyclovir hospital discharge" group required CMV directed treatment (p = 0.005 and 0.06 comparing letermovir to "valacyclovir hospital discharge" and "valacyclovir day 100"). Fewer patients in the letermovir group (n = 7, 22%) had any CMV reactivation versus the "valacyclovir day 100" group (n = 20, 33%) versus the "valacyclovir hospital discharge" group (n = 23, 57%) (p = 0.003 and 0.21 comparing letermovir to "valacyclovir hospital discharge" and "valacyclovir day 100"). Among patients not reactivating CMV before 100 days, reactivation rates between day 100 and 180 were higher in the letermovir and "valacyclovir day 100" groups than the "valacyclovir hospital discharge" group. Letermovir is safe and effective compared with alternative prophylaxis approaches following CBT through day 100. Reactivation and monitoring after day 100 remain potential concerns.

Chronic Myeloid Leukemia, Version 1.2019, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph), resulting from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor (TKI) therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML (CP-CML). The selection TKI therapy should be based on the risk score, toxicity profile of TKI, patient's age, ability to tolerate therapy, and the presence of comorbid conditions. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with CP-CML.

CD123 CAR T cells for the treatment of myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a group of heterogeneous disorders caused by ineffective hematopoiesis and characterized by bone marrow dysplasia and cytopenia. Current treatment options for MDS are limited to supportive care, hypomethylating agents, and stem cell transplant. Most patients eventually succumb to the disease or progress to leukemia. Previously, we found that CD123 can be used to delineate MDS stem cells in patients at high risk for MDS and that the CD123-positive population is biologically distinct from normal hematopoietic stem cells. Furthermore, selective targeting of MDS stem cells can dramatically reduce tumor burden in preclinical models. On the basis of these findings, we propose CD123 as a candidate target for chimeric antigen receptor (CAR) T-cell therapy in high-risk MDS patients. To test this concept, we employed a CAR lentiviral vector containing a CD123-specific single-chain variable fragment in combination with the CD28 costimulatory domain, CD3ζ signaling domain, and truncated estimated glomerular filtration rate. Utilizing this system, we illustrate that CD123 CAR can be expressed on both healthy donor and MDS patient-derived T lymphocytes with high efficiency, leading to the successful elimination of MDS stem cells both in vitro and in patient-derived xenografts. These results provide the concept for the use of CD123-targeted CAR T cells as a therapeutic option for patients with MDS.

Clickable Methyltetrazine-Indocarbocyanine Lipids: A Multicolor Tool Kit for Efficient Modifications of Cell Membranes

Cell-based therapeutics are one of the most promising and exciting breakthroughs in modern medicine. Modification of the cell surface with ligands, biologics, drugs, and nanoparticles can further enhance the functionality. Previously, we described the synthesis of a dioctadecyl indocarbocyanine Cy3 analog (aminomethyl-DiI) for efficient and stable modification (painting) of mouse erythrocytes with small molecules, enzymes, and biologics. Here, we synthesized a near-infrared aminomethyl dioctadecyl derivative of Cy7 (aminomethyl-DOCy7) and systematically compared it to aminomethyl-DiI as an anchor for the modification of human erythrocytes, Jurkat cells, and primary T cells with immunoglobulin G. To enable copper-free click chemistry modification of cell membranes, we conjugated a methyltetrazine (MTz) group to the amino-indocyanine lipids via a polyethylene glycol (PEG) linker. DOCy7-PEG3400-MTz showed over 99% modification efficiency of human red blood cells (RBCs) at 25 μM. Reaction of trans-cyclooctene (TCO) modified immunoglobulin G (IgG) with DOCy7-PEG₄-MTz-modified RBCs (2-step method) resulted in ∼80,000 IgG molecules per erythrocyte, whereas modification with a preconjugated DOCy7-PEG3400-IgG construct (1-step method) resulted in ∼20,000 IgG molecules per erythrocyte as detected by immuno dot-blot. The number of IgG/RBC was controlled by the concentration of IgG. The incubation of RBCs with DiI-PEG3400-MTz resulted in a similar number of IgG/RBC. Modification of the T-lymphocyte cell line Jurkat with IgG resulted in ∼1 × 10⁶ IgG/cell with the 1-step and 2-step methods, and the efficiency was similar for DOCy7 and DiI constructs. Finally, we used DOCy7 and DiI constructs to demonstrate efficient modification of primary CD3+T cells from healthy donors. In conclusion, click indocarbocyanine conjugates represent a novel multicolor chemical biology tool kit for efficient surface modification of different cells types and can be used for potential imaging and drug delivery applications involving engineered cells.

Subversion of Systemic Glucose Metabolism as a Mechanism to Support the Growth of Leukemia Cells

From an organismal perspective, cancer cell populations can be considered analogous to parasites that compete with the host for essential systemic resources such as glucose. Here, we employed leukemia models and human leukemia samples to document a form of adaptive homeostasis, where malignant cells alter systemic physiology through impairment of both host insulin sensitivity and insulin secretion to provide tumors with increased glucose. Mechanistically, tumor cells induce high-level production of IGFBP1 from adipose tissue to mediate insulin sensitivity. Further, leukemia-induced gut dysbiosis, serotonin loss, and incretin inactivation combine to suppress insulin secretion. Importantly, attenuated disease progression and prolonged survival are achieved through disruption of the leukemia-induced adaptive homeostasis. Our studies provide a paradigm for systemic management of leukemic disease.

Characterization of clinical grade CD19 chimeric antigen receptor T cells produced using automated CliniMACS Prodigy system

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy is highly effective for treating acute lymphoblastic leukemia and non-Hodgkin's lymphoma with high rate complete responses. However, the broad clinical application of CAR T-cell therapy has been challenging, largely due to the lack of widespread ability to produce and high cost of CAR T-cell products using traditional methods of production. Automated cell processing in a closed system has emerged as a potential method to increase the feasibility of producing CAR T cells locally at academic centers due to its minimal reliance on experienced labor, thereby making the process less expensive and more consistent than traditional methods of production.

METHOD

In this study, we describe the successful production of clinical grade CD19 CAR T cells using the Miltenyi CliniMACS Prodigy Automated Cell Processor at University of Colorado Anschutz Medical Campus in a rapid manner with a high frequent CD19 CAR expression.

RESULTS

The final CAR T-cell product is highly active, low in immune suppression, and absent in exhaustion. Full panel cytokine assays also showed elevated production of Th1 cytokines upon IL-2 stimulation when specifically killing CD19+ target cells.

CONCLUSION

These results demonstrate the feasibility of producing CAR T cells locally in a university hospital setting using automated cell processor for future clinical applications.

Thiotepa-Based Intensified Reduced-Intensity Conditioning Adult Double-Unit Cord Blood Hematopoietic Stem Cell Transplantation Results in Decreased Relapse Rate and Improved Survival Compared with Transplantation Following Standard Reduced-Intensity Conditioning: A Retrospective Cohort Comparison

The "Minnesota" reduced-intensity conditioning (RIC) cord blood transplantation (CBT) regimen (standard RIC) of fludarabine (Flu) (200 mg/m²), cyclophosphamide (Cy) (50 mg/kg), and 200- or 300-cGy total body irradiation (TBI) is the most published RIC CBT regimen. Though well tolerated, high relapse rates remain a concern with this regimen. Intensification of conditioning may reduce relapse without increasing transplant-related mortality (TRM). We performed a retrospective cohort comparison of outcomes in adult patients who underwent first double-unit CBT with standard RIC as compared with the intensified regimen of Flu 150 mg/m², Cy 50 mg/kg, thiotepa 10 mg/kg, and 400-cGy TBI (intensified RIC). Of the 99 patients studied, 47 received intensified RIC. Acute myelogenous leukemia was the major indication for transplant. The median age at transplant was 67 years (range, 24 to 74 years) and 54 years (range, 25 to 67 years) in standard RIC and intensified RIC, respectively. Median hematopoietic stem cell transplantation comorbidity index was 3 (range, 0 to 5) and 1 (range, 0 to 6) in the standard RIC and intensified RIC groups, respectively. Median follow-up among survivors was 22 months (range, 3.7 to 79 months) following standard RIC and 15 months (range, 2.8 to 36 months) following intensified RIC. The cumulative incidence (CI) of relapse was significantly lower following intensified RIC compared with standard RIC (P = .0013); this finding maintained significance in multivariate analysis (P = .045). TRM was comparable between the 2 groups (P = .99). Overall survival (OS) was significantly improved following intensified RIC as compared with standard RIC (P = .03). Median OS was 17 months following standard RIC versus not reached followed intensified RIC. The CI of grade II to IV acute graft-versus-host disease (GVHD) was significantly higher in the intensified RIC cohort than the standard RIC-cohort (P = .007), while CI of grade III to IV acute GVHD, any chronic GVHD, and moderate-to-severe chronic GVHD was comparable in each cohort (P = .20, P = .21, and P = .61, respectively). This retrospective analysis shows an improvement in OS and decreased relapse without increase in TRM in patients receiving intensified RIC as compared with standard RIC. Our data suggest that consideration of thiotepa-based intensified RIC may improve outcomes in fit, older patients undergoing double-unit CBT.

Allogeneic transplantation using CD34+ selected peripheral blood progenitor cells combined with non-mobilized donor T cells for refractory severe aplastic anaemia

Allogeneic haematopoietic stem cell transplantation is curative for severe aplastic anaemia (SAA) unresponsive to immunosuppressive therapy. To reduce chronic graft-versus-host disease (GVHD), which occurs more frequently after peripheral blood stem cell (PBSC) transplantation compared to bone-marrow transplantation (BMT), and to prevent graft rejection, we developed a novel partial T-cell depleted transplant that infuses high numbers of granulocyte colony-stimulating factor-mobilized CD34⁺ selected PBSCs combined with a BMT-equivalent dose of non-mobilized donor T-cells. Fifteen patients with refractory SAA received cyclophosphamide, anti-thymocyte globulin and fludarabine conditioning, and were transplanted with a median 8 × 10⁶ CD34⁺  cells/kg and 2 × 10⁷ non-mobilized CD3⁺ T-cells/kg from human leucocyte antigen-matched sibling donors. All achieved sustained engraftment with only two developing acute and two developing chronic GVHD. With a 3·5-year median follow-up, 86% of patients survived and were transfusion-independent. When compared to a retrospective cohort of 56 bone-marrow failure patients that received the identical transplant preparative regimen and GVHD prophylaxis with the exception that the allograft contained unmanipulated PBSCs, partial T-cell depleted transplant recipients had delayed donor T-cell chimerism and relative reduction of 75% in the incidence of acute grade II-IV GVHD (13% vs. 52%; P = 0·010) and of 82% in chronic GVHD (13% vs. 72%; P = 0·0004). In multivariate analysis, partial T-cell depleted transplants remained significantly associated with a reduced risk of GVHD. In conclusion, for patients with refractory SAA, this novel transplant strategy achieves excellent engraftment and survival when compared to unmanipulated PBSC transplants and dramatically reduces the incidence of both acute and chronic GVHD.

Effect of high-dose plerixafor on CD34+ cell mobilization in healthy stem cell donors: results of a randomized crossover trial

Hematopoietic stem cells can be mobilized from healthy donors using single-agent plerixafor without granulocyte colony-stimulating factor and, following allogeneic transplantation, can result in sustained donor-derived hematopoiesis. However, when a single dose of plerixafor is administered at a conventional 240 μg/kg dose, approximately one-third of donors will fail to mobilize the minimally acceptable dose of CD34⁺ cells needed for allogeneic transplantation. We conducted an open-label, randomized trial to assess the safety and activity of high-dose (480 μg/kg) plerixafor in CD34⁺ cell mobilization in healthy donors. Subjects were randomly assigned to receive either a high dose or a conventional dose (240 μg/kg) of plerixafor, given as a single subcutaneous injection, in a two-sequence, two-period, crossover design. Each treatment period was separated by a 2-week minimum washout period. The primary endpoint was the peak CD34⁺ count in the blood, with secondary endpoints of CD34⁺ cell area under the curve (AUC), CD34⁺ count at 24 hours, and time to peak CD34⁺ following the administration of plerixafor. We randomized 23 subjects to the two treatment sequences and 20 subjects received both doses of plerixafor. Peak CD34⁺ count in the blood was significantly increased (mean 32.2 versus 27.8 cells/μL, P=0.0009) and CD34⁺ cell AUC over 24 hours was significantly increased (mean 553 versus 446 h cells/μL, P<0.0001) following the administration of the 480 μg/kg dose of plerixafor compared with the 240 μg/kg dose. Remarkably, of seven subjects who mobilized poorly (peak CD34⁺ ≤20 cells/μL) after the 240 μg/kg dose of plerixafor, six achieved higher peak CD34⁺ cell numbers and all achieved higher CD34⁺ AUC over 24 hours after the 480 μg/kg dose. No grade 3 or worse drug-related adverse events were observed. This study establishes that high-dose plerixafor can be safely administered in healthy donors and mobilizes greater numbers of CD34⁺ cells than conventional-dose plerixafor, which may improve CD34⁺ graft yields and reduce the number of apheresis procedures needed to collect sufficient stem cells for allogeneic transplantation. (ClinicalTrials.gov, identifier: NCT00322127)

Divalent cation-responsive myotonia and muscle paralysis in skeletal muscle sodium channelopathy

We report a patient with paramyotonia congenita/hyperkalemic periodic paralysis due to Nav1.4 I693T mutation who had worsening of myotonia and muscle weakness in the setting of hypomagnesemia and hypocalcemia with marked recovery after magnesium administration. Computer simulations of the effects of the I693T mutation were introduced in the muscle fiber model by both hyperpolarizing shifts in the Nav1.4 channel activation and a faster recovery from slow channel inactivation. A further shift in the Nav1.4 channel activation in the hyperpolarizing direction as expected with low divalent cations resulted in myotonia that progressed to membrane inexcitability. Shifting the channel activation in the depolarizing direction as would be anticipated from magnesium supplementation abolished the myotonia. These observations provide clinical and biophysical evidence that the muscle symptoms in sodium channelopathy are sensitive to divalent cations. Exploration of the role of magnesium administration in therapy or prophylaxis is warranted with a randomized clinical trial.

Translocation (8;21) acute myeloid leukemia presenting as severe aplastic anemia

We report a case of t(8;21) acute myeloid leukemia presenting as severe aplastic anemia. While initial bone marrow biopsy lacked any cytogenetic abnormalities in 20 analyzed metaphases, repeat bone marrow biopsy eight days later demonstrated this translocation. Initial cytogenetic analysis of 20 metaphases was therefore insufficient to make the diagnosis of hypocellular acute myeloid leukemia. We discuss that further complementary molecular tests, such as CGH, would likely provide a more robust diagnosis of hematopoietic diseases.

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It is difficult to distinguish between hypocellular MDS, hypocellular AML and SAA.

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Acute leukemia may present as SAA.

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20 Metaphases may be insufficient to diagnose hypocellular AML.

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Complementary methods, such as SNP based CGH arrays, would enhance the diagnosis.

PP2A interaction with Rb2/p130 mediates translocation of Rb2/p130 into the nucleus in all-trans retinoic acid-treated ovarian carcinoma cells

One of the mechanisms by which all-trans retinoic acid (ATRA) has been shown to suppress the growth of CAOV3 ovarian carcinoma cells involves an increase in the accumulation of Rb2/p130 protein, a member of the retinoblastoma family of tumor suppressors. This increase in accumulation of RB2/p130 by ATRA results from increased stability of Rb2/p130 protein as a result of an increase in dephosphorylation of the protein by the serine/threonine phosphatase PP2A. We show that upon ATRA treatment, PP2A interacts with the Rb2/p130 C-terminus and specifically dephosphorylates two residues (S1080 and T1097) adjacent to NLS1 and NLS2 of Rb2/p130. Moreover, co-immunoprecipitation studies reveal that Rb2/p130 can form a complex with the nuclear transport proteins, importin α and importin β, binding to the same dephosphorylated NLS1 and NLS2 sites. Finally, mutation of S1080 and T1097 results in retension of Rb2/p130 in the cytoplasm. Our studies suggest that one mechanism by which ATRA treatment of CAOV3 cells induces G0/G1 arrest involves the recruitment of PP2A to the C-terminus of Rb2/p130, resulting in the dephosphorylation of the S1080 and T1097 adjacent to the NLS and the subsequent interaction of Rb2/p130 with importins leading to transport of the Rb2/p130 to the nucleus where it inhibits cell-cycle progression.

c-Cbl and Cbl-b act redundantly to protect osteoclasts from apoptosis and to displace HDAC6 from beta-tubulin, stabilizing microtubules and podosomes

c-Cbl and Cbl-b are highly conserved adaptor proteins that participate in integrin signaling, regulating cytoskeletal organization, motility, and bone resorption. Deletion of both c-Cbl and Cbl-b in mice leads to embryonic lethality, indicating that the two proteins perform essential redundant functions. To examine the redundant actions of c-Cbl and Cbl-b in osteoclasts, we depleted c-Cbl in Cbl-b(-/-) osteoclasts by using a short hairpin RNA. Depleting both Cbl proteins disrupted both the podosome belt and the microtubule network and decreased bone-resorbing activity. Stabilizing the microtubules with paclitaxel or inhibiting histone deacetylase 6 (HDAC6), which destabilizes microtubules by deacetylating beta-tubulin, protected both the microtubule network and the podosome belt. Examination of the mechanism involved demonstrated that the conserved four-helix bundle of c-Cbl's tyrosine kinase binding domain bound to beta-tubulin, and both c-Cbl and Cbl-b displaced HDAC6. In addition to the effects on microtubules and the podosome belt, depleting both Cbls significantly increased the levels of the proapoptotic protein Bim and apoptosis relative to the levels induced by eliminating either protein alone. Thus, both c-Cbl and Cbl-b promote bone resorption via the stabilization of microtubules, allowing the formation of the podosome belt in osteoclasts, and by promoting osteoclast survival.

Identification and functional characterization of an Src homology domain 3 domain-binding site on Cbl

Cbl is an adaptor protein and ubiquitin ligase that binds and is phosphorylated by the nonreceptor tyrosine kinase Src. We previously showed that the primary interaction between Src and Cbl is mediated by the Src homology domain 3 (SH3) of Src binding to proline-rich sequences of Cbl. The peptide Cbl RDLPPPPPPDRP(540-551), which corresponds to residues 540-551 of Cbl, inhibited the binding of a GST-Src SH3 fusion protein to Cbl, whereas RDLAPPAPPPDR(540-551) did not, suggesting that Src binds to this site on Cbl in a class I orientation. Mutating prolines 543-548 reduced Src binding to the Cbl 479-636 fragment significantly more than mutating the prolines in the PPVPPR(494-499) motif, which was previously reported to bind Src SH3. Mutating Cbl prolines 543-548 to alanines substantially reduced Src binding to Cbl, Src-induced phosphorylation of Cbl, and the inhibition of Src kinase activity by Cbl. Expressing the mutated Cbl in osteoclasts induced a moderate reduction in bone-resorbing activity and increased amounts of Src protein. In contrast, disabling the tyrosine kinase-binding domain of full-length Cbl by mutating glycine 306 to glutamic acid, and thereby preventing the previously described binding of the tyrosine kinase-binding domain to the Src phosphotyrosine 416, had no effect on Cbl phosphorylation, the inhibition of Src activity by full-length Cbl, or bone resorption. These data indicate that the Cbl RDLPPPP(540-546) sequence is a functionally important binding site for Src.

High-grade glioma formation results from postnatal pten loss or mutant epidermal growth factor receptor expression in a transgenic mouse glioma model

High-grade gliomas are devastating brain tumors associated with a mean survival of <50 weeks. Two of the most common genetic changes observed in these tumors are overexpression/mutation of the epidermal growth factor receptor (EGFR) vIII and loss of PTEN/MMAC1 expression. To determine whether somatically acquired EGFRvIII expression or Pten loss accelerates high-grade glioma development, we used a previously characterized RasB8 glioma-prone mouse strain, in which these specific genetic changes were focally introduced at 4 weeks of age. We show that both postnatal EGFRvIII expression and Pten inactivation in RasB8 mice potentiate high-grade glioma development. Moreover, we observe a concordant loss of Pten and EGFR overexpression in nearly all high-grade gliomas induced by either EGFRvIII introduction or Pten inactivation. This novel preclinical model of high-grade glioma will be useful in evaluating brain tumor therapies targeted to the pathways specifically dysregulated by EGFR expression or Pten loss.

Rb2/p130 and protein phosphatase 2A: key mediators of ovarian carcinoma cell growth suppression by all-trans retinoic acid

Despite a number of attempts to improve treatment of ovarian cancer, it remains the most common cause of death from gynecological cancers. Thus, it is very important to identify more effective drugs for treatment and prevention of ovarian cancer. All-trans-retinoic acid (ATRA) has been shown to arrest the growth of ovarian carcinoma cells in G0/G1 and to significantly elevate levels of Rb2/p130 protein, a member of the retinoblastoma family of tumor suppressors. As ATRA treatment leads to a significant increase in the amount of Rb2/p130 protein but not mRNA, the elevated levels of Rb2/p130 protein is likely the result of increased stability. In studies to elucidate the mechanism by which ATRA alters Rb2/p130 stability in ovarian cancer cells, it was determined that PP2A, a serine/threonine phosphatase, binds and dephosphorylates Rb2/p130. Dephosphorylated Rb2/p130 exhibits decreased ubiquitination and thus is not degraded by the proteasome. The sites at which PP2A catalytic subunit (PP2Ac) interacts with Rb2/p130 have been localized to the NLS in the C-terminus of Rb2/p130. These sites are also involved in the interaction of Rb/p130 with importin beta and importin alpha, members of the nuclear transport machinery. It is known that importin alpha recognizes a NLS on a target protein and importin beta binds the nuclear pore complex. Moreover, it has been shown that the binding of importin alpha to NLS significantly decreases with phosphorylation of NLS. In ATRA-treated ovarian carcinoma cells, PP2A binds to Rb2/p130 and dephosphorylates the NLS of Rb2/p130 leading to the interaction of importin alpha with Rb2/p130. Importin beta then binds to the importin alpha-Rb2/p130 complex, leading to the translocation of the Rb2/p130 to the nucleus where it acts to arrest ovarian cancer cells in G1 and suppress proliferation.

Serum antibodies to EpCAM in healthy donors but not ulcerative colitis patients

PURPOSE

The gastrointestinal carcinoma-associated antigen epithelial cell adhesion molecule (EpCAM) has been a target for passive and active immunotherapy of gastrointestinal carcinoma patients. The antigen is expressed by both tumor and normal tissues. The immunogenicity of EpCAM in colorectal cancer patients has been described previously. The purpose of this study was to evaluate humoral and cellular immune responses of healthy individuals and ulcerative colitis patients to EpCAM and to relate immune responses to colonic tissue expression of EpCAM.

METHODS

An inhibition radioimmunoassay was used to detect anti-EpCAM serum antibodies. Anti-EpCAM antibodies of a healthy donor were expressed by phages and sequenced. (3)H-thymidine incorporation assay was used for detection of lymphoproliferative responses to stimulation with EpCAM. EpCAM tissue expression was determined by immunohistochemistry.

RESULTS

We detected anti-EpCAM serum antibodies in 4 of 10, and EpCAM-specific lymphoproliferation responses in 1 of 10 healthy volunteers. The majority of anti-EpCAM antibodies derived from a healthy donor were germline-encoded. In contrast, none of the 23 patients with ulcerative colitis showed serum antibodies to EpCAM (P=0.005). Antigen expression was greatly reduced and altered in ulcerative colitis patients, whereas colon from healthy individuals and uninvolved colon of colorectal cancer patients expressed high levels of EpCAM.

CONCLUSION

The results of these studies suggest an association between EpCAM antibody production and colonic EpCAM expression in healthy individuals and patients with ulcerative colitis. Decreased and altered colonic EpCAM expression in ulcerative colitis patients may be related to the disease induction, based on the previously demonstrated adhesion function of this molecule. Healthy individuals with anti-EpCAM immune responses and high risk for developing colorectal carcinoma are prime candidates for prophylactic immunization against EpCAM.

Interaction of PP2A catalytic subunit with Rb2/p130 is required for all-trans retinoic acid suppression of ovarian carcinoma cell growth

All-trans retinoic acid (ATRA) treatment causes CAOV3 ovarian carcinoma cells to growth arrest in the G0/G1 phase and to elevate the level of Rb2/p130 protein. PP2A, a serine/threonine phosphatase, binds and dephosphorylates Rb2/p130, thereby increasing the half-life of Rb2/p130 in the cell. In order to further characterize the interaction between Rb2/p130 and PP2A upon ATRA treatment, we examined the posttranslational modification of PP2A. ATRA treatment leads to hypophosphorylation of PP2A catalytic subunit (PP2Ac) that correlates with increased PP2A activity. In addition, the N-terminus of PP2Ac binds directly to NLS sequences located in the C-terminus of Rb2/p130. Furthermore, CAOV3 cells transfected with a truncated Rb2/p130 construct consisting of only the wt C-terminus grew more aggressively and were less sensitive to ATRA treatment when compared to parental CAOV3 cells. In contrast, CAOV3 cells transfected with a truncated Rb2/p130 construct consisting of only the C-terminus in which the NLS sites were mutated and which could not interact with PP2A, were as sensitive to ATRA treatment as parental CAOV3 cells. These studies suggest that ATRA treatment suppresses the growth of CAOV3 cells via a novel posttranscriptional mechanism involving PP2A.

Immune responses of breast cancer patients to mutated epidermal growth factor receptor (EGF-RvIII, Delta EGF-R, and de2-7 EGF-R)

Mutated epidermal growth factor receptor (EGF-RvIII, DeltaEGF-R, and de2-7 EGF-R) is the result of an 801-bp deletion within the extracellular domain of wild-type EGF-R and is expressed by breast carcinomas, but not by normal breast tissues. EGF-RvIII is expressed both on the surface and in the cytoplasm of tumor cells. Thus, EGF-RvIII is a potential tumor-specific target for both Abs and T cells. However, it is not known whether breast cancer patients can raise immune responses to EGF-RvIII expressed by their tumors. The demonstration of EGF-RvIII-specific immune responses in patients would suggest that immunization of patients with EGF-RvIII vaccines is feasible, because these vaccines may boost a pre-existing immune response. We have evaluated humoral and cellular immune responses to EGF-RvIII in 16 breast cancer patients and three healthy donors. Seven of 16 patients developed EGF-RvIII-specific Abs that bound to isolated EGF-RvIII protein or the protein expressed by EGF-RvIII-transfected mouse fibroblasts. The Abs that bound to EGF-RvIII did not bind to wild-type EGF-R, and anti-EGF-RvIII Abs were not found in the sera of healthy donors. Three patients had EGF-RvIII peptide-specific lymphoproliferative responses, and two of these patients also had humoral immune responses. Humoral and cellular immune responses correlated with EGF-RvIII expression by patients' tumors in most cases. These studies demonstrate that breast cancer patients specifically recognize EGF-RvIII with an overall immune response rate of 50%, suggesting that patients may benefit from vaccination against EGF-RvIII, boosting pre-existing immune responses.

Effect of all-trans retinoic acid on telomerase activity in ovarian cancer cells

Vitamin A is an essential nutrient important for growth, vision, embryonic development, immune response and reproduction. Various retinoids have been shown to be effective chemotherapeutic and chemopreventive agents for a number of human cancers. Telomeres are nucleoprotein structures found at the end of chromosomes. During cellular division, the telomeres in normal cells shorten progressively and thus, function as a "molecular clock". Telomerase is a ribonucleoprotein complex that extends and maintains telomeres. Activation of telomerase is required for cells to overcome proliferative crisis. Telomerase activation is observed in 90% of human cancers, but not in normal somatic cells. We examined the role of telomerase in mediating the growth suppression of ovarian carcinoma cells by all-trans-retinoic acid (ATRA). Using a number of cell lines with varying levels of growth sensitivity to ATRA, we found that cells that exhibit ATRA-dependant suppression of growth also contained significantly reduced telomerase activity. We also observed a reduction in expression of the telomerase components, hTERT and hTR in ATRA treated ovarian carcinoma cells. Our results suggest that one mechanism by which ATRA acid inhibits cancer cell growth is by suppressing telomerase activity, thereby pushing cells to proliferative crisis.

Protein phosphatase 2A associates with Rb2/p130 and mediates retinoic acid-induced growth suppression of ovarian carcinoma cells

Levels of Rb2/p130 protein are increased 5-10-fold following all-trans-retinoic acid (ATRA) treatment of the retinoid-sensitive ovarian adenocarcinoma cell line CAOV3, but not the retinoid-resistant adenocarcinoma cell line SKOV3. We found that this increase in Rb2/p130 protein levels in ATRA-treated CAOV3 cells was the result of an increased protein stability. Moreover, Rb2/p130 exhibited a decreased ubiquitination following ATRA treatment. Because phosphorylation frequently mediates ubiquitination of proteins, we examined the serine/threonine phosphatase activity in our CAOV3 cells following ATRA treatment. A significant increase in Ser/Thr phosphatase activity was found, which correlated with a rise in the level of protein phosphatase 2A (PP2A) catalytic subunit-alpha. In addition, co-immunoprecipitation and glutathione S-transferase pull-down studies demonstrated that PP2A and Rb2/p130 associate. We have made use of a battery of Rb2/p130 mutants to determine the sites dephosphorylated in response to ATRA treatment of CAOV3 cells. Obligate CDK4 phosphorylation sites seemed most important to the stability of the protein and are among the candidate sites that are dephosphorylated by PP2A following ATRA treatment. Finally, using both small interfering RNA specific to the catalytic subunit of PP2A and a variant of the SKOV3 cell line that overexpresses PP2A, we have shown that modulation of PP2A protein levels correlates with the ability of ATRA to inhibit growth of ovarian carcinoma cells. Our data suggest that ATRA mediates growth inhibition by stabilizing Rb2/p130 via a mechanism that involves induction of PP2A, an enzyme that can potentially dephosphorylate Rb2/p130, thereby protecting it from degradation by the proteasome.

Monoclonal anti-idiotypic antibody mimicking the gastrointestinal carcinoma-associated epitope CO17-1A elicits antigen-specific humoral and cellular immune responses in colorectal cancer patients

Monoclonal rat anti-idiotypic antibody (Ab2) BR3E4 mimicking the colorectal carcinoma (CRC)-associated epitope CO17-1A induced antigen-specific humoral and cellular immune responses in mice and rabbits. Ab2 BR3E4 was administered in a phase I trial to CRC patients either as intact IgG or as F(ab')(2) coupled to keyhole limpet hemocyanin (KLH). There was a trend for the F(ab')(2)-KLH-immunized patients to show higher immune response rates (18/21 and 5/15 patients with anti-anti-idiotypic antibodies and T cells, respectively) than the IgG-immunized patients (15/23 and 3/15 patients positive). Clinical responses were rare in these patients with liver metastases.

Induction of cellular immunity by anti-idiotypic antibodies mimicking GD2 ganglioside

Gangliosides are potentially useful targets for tumor destruction by antibodies. However, the role of gangliosides in T cell-mediated immunity to tumors is unclear. We produced three murine monoclonal anti-idiotypic antibodies (Ab2) against a monoclonal antibody (Ab1) that binds strongly to melanoma-associated GD2 ganglioside and weakly to GD3 ganglioside. All three Ab2 induced anti-anti-idiotypic antibodies (Ab3) with Ab1-like binding specificity to tumor cells and antigen in rabbits. The Ab3 specifically bound to GD2(+) tumor cells and isolated GD2, and shared idiotopes with the Ab1. Two of the three Ab2 induced GD2-specific delayed-type hypersensitivity responses in BALB/c and C57BL/6 mice, but not in C57BL/6/CD4(-/-) mice. Peripheral blood mononuclear cells (PBMC) from a melanoma patient proliferated specifically in response to in vitro stimulation with Ab2. Proliferation was accompanied by Th1-type cytokine production. Our studies demonstrate the induction of ganglioside-specific T cell-dependent immunity by Ab2 in mice. These T cells showed specific reactivity to ganglioside expressed by tumor cells.

Anti-idiotypic antibody (ab2) vaccines: coupling of Ab2 BR3E4 to KLH increases humoral and/or cellular immune responses in animals and colorectal cancer patients

The colorectal carcinoma (CRC)-associated CO17-1A/GA733 antigen (Ag) has been the target of a phase II/III randomized trial of passive immunotherapy with monoclonal antibody CO17-1A (Ab1), and phase I active immunotherapy trials with polyclonal anti-idiotypic antibodies (Ab2) mimicking the CO17-1A or GA733 epitope of the Ag. However, monoclonal rat Ab2 BR3E4 directed against Ab1 CO17-1A was superior to polyclonal Ab2 in inducing antigen-specific humoral and cellular immune responses in mice and rabbits. Various forms of Ab2 BR3E4, i.e., BR3E4-F(ab')2 precipitated with aluminum-hydroxide (alum), BR3E4-F(ab')2 coupled to KLH and precipitated or non-precipitated with alum, and BR3E4-IgG in alum or incomplete Freund's adjuvant were compared for their capacity to induce in rabbits anti-anti-idiotypic antibodies (Ab3) that specifically bind to the CO17-1A Ag. BR3E4-F(ab')2 coupled to KLH and precipitated with alum was shown to induce the highest Ab3 titers, followed by Ab2 BR3E4-IgG in alum. Therefore Ab2 BR3E4 as intact IgG (IgG group) or as F(ab')2 coupled to KLH (KLH group), was administered in a phase I trial to 45 patients with CRC, stage Dukes'D (UICC stage IV), with the goal to modulate patients' immune responses to their tumors. Fifteen of 23 patients in the IgG group developed Ab3 binding specifically to Ab2, and in four of these patients the Ab3 also specifically bound to Ag-positive CRC cells. Lymphoproliferative responses to Ab2 and/or GA733-2E Ag stimulation were observed in three of these patients. Eighteen of the 22 KLH group patients tested developed Ab3 and the Ab3 bound specifically to CRC cells in eight patients. Five of the 15 KLH group patients tested developed lymphoproliferative responses to Ab2 and/or GA733-2E Ag. Thus, there was a trend for the KLH group demonstrating higher immune response rates than the IgG group. Clinical responses were rare in these patients with liver metastases.

Anti-idiotypic antibody and recombinant antigen vaccines in colorectal cancer patients

The colorectal carcinoma (CRC)-associated GA733 antigen (also known as CO17-1A, KS1-4, KSA or EpCAM) has been the target of a phase II/III randomized trial of passive immunotherapy with monoclonal antibody CO17-1A and phase I active immunotherapy trials with polyclonal anti-idiotypic antibodies mimicking the CO17-1A or GA733 epitope on the antigen. The CO17-1A antigen was molecularly cloned and the extracellular domain expressed in baculovirus (BV) GA733-2E. Whereas, anti-idiotypic antibody mimics a single epitope on the antigen, BV GA733-2E expresses multiple potentially immunogenic epitopes. In animals, the immunogenicity of BV GA733-2E in aluminum hydroxide was superior to that of anti-idiotype in the same adjuvant. Here, we compared the immunogenicity of anti-idiotypic antibody and GA733-2E antigen in CRC patients. These studies indicate that the antigen is superior to the anti-idiotype antibody in inducing humoral and cellular immunity in CRC patients.

Immunogenicity of recombinant GA733-2E antigen (CO17-1A, EGP, KS1-4, KSA, Ep-CAM) in gastro-intestinal carcinoma patients

Targeting the GA733 antigen (also known as CO17-1A, EGP, KS1-4, KSA, Ep-CAM) by monoclonal antibody CO17-1A or anti-idiotypic antibodies mimicking the CO17-1A or GA733 epitope has induced prolonged survival and specific immune responses to the antigen, respectively, in colorectal cancer (CRC) patients. In pre-clinical studies in mice and rabbits, recombinant baculovirus-derived GA733-2E antigen was superior to anti-idiotypic antibodies at modulating specific immune responses. Our aim was to evaluate the immunogenicity and potential toxicity of alum-precipitated GA733-2E in a phase I trial in patients with resected CRC or pancreatic cancer. Six patients with advanced pancreatic carcinoma and 6 with CRC Dukes' stage A, B or C received between 4 and 7 doses of alum-precipitated GA733-2E at 50, 200 or 800 microg/dose at monthly intervals. Antibody binding to GA733-2E or antigen-positive CRC cells was determined, as were antigen-specific proliferative, cytolytic T-lymphocyte and delayed-type hypersensitivity responses. Six of the 12 patients developed antigen-specific humoral immune responses after immunotherapy, and 8 developed cellular immune responses. The overall immune response rate, including patients with humoral and/or cellular immune responses, was 83%. Median overall survival of the CRC and pancreatic cancer patients was 39.8 and 11.2 months, respectively. Following 18 years of single-epitope targeting of the GA733 antigen, immunization of patients against multiple epitopes of the antigen frequently induces an immune response in the absence of significant toxicity, despite relatively widespread expression of this antigen on normal epithelial cells.

Cutting edge: C3, a key component of complement activation, is not required for the development of myelin oligodendrocyte glycoprotein peptide-induced experimental autoimmune encephalomyelitis in mice

Experimental autoimmune encephalomyelitis (EAE), an inflammatory demyelinating disease of the CNS, is regarded as an experimental model for multiple sclerosis. The complement has been implicated in the pathogenesis of multiple sclerosis. To clarify the role of C in mouse EAE, we immunized mice deficient in C3 (C3(-/-)) and their wild-type (C3(+/+)) littermates with myelin oligodendrocyte glycoprotein peptide 35-55. C3(-/-) mice were susceptible to EAE as much as the C3(+/+) mice were. No differences were found for the production of IL-2, IL-4, IL-12, TNF-alpha, and IFN-gamma between C3(+/+) and C3(-/-) mice. This finding shows that C3, a key component in C activation, is not essential in myelin oligodendrocyte glycoprotein peptide-induced EAE in mice.

Flow cytometric analysis of infiltrating cells in the peripheral nerves in experimental allergic neuritis

Experimental autoimmune neuritis (EAN) is an animal model that shares clinical, pathological and electrophysiological features with the human disease Guillain-Barré syndrome (GBS). In this study, we isolated and characterized by fluorescent activated cell sorter (FACS) phenotype of the inflammatory cells infiltrating cauda equina (CE) of Lewis rats at the active stage of the disease. We found that at this stage of EAN macrophages (Mphi) and alphabeta T cells were two major populations isolated from CE. We also found that among total cell population isolated from CE, gammadelta T and NK cells composed two small but distinct populations, while B cells were negligible. We characterized phenotype of alphabeta T cells in CE as CD45RC(+)CD8(+) (activated cytotoxic lymphocytes) and CD45RC(-)CD4(+) (memory Th cells). The phenotype of gammadelta T cells was found to be consisted of only CD45RC(+)CD8(+) cells. Both alphabeta and gammadelta T cells in CE expressed a higher level of CD25, CD44 and CD54 activation markers compared to the other tissues. Immunohistochemistry demonstrated that gammadelta T cells existed apart from the intense cellular infiltrate. This is the first report on the isolation and FACS analysis of CE-infiltrating cells, contributing a new and alternative approach to study the inflammatory lesions in EAN. We conclude that both alphabeta and gammadelta T cells have a unique activation/inflammatory phenotype required to traffic through and be retained in the peripheral nerves during EAN.

Colorectal cancer vaccines: antiidiotypic antibody, recombinant protein, and viral vector

The colorectal cancer antigen GA733 (also termed CO17-1A, KSI-4, Ep-CAM, KSA) has proved to be a useful target in passive immunotherapy with monoclonal antibody and in active immunotherapy with antiidiotypic antibodies in cancer patients. The GA733 antigen was molecularly cloned and expressed in baculovirus (BV), adenovirus (AV), and vaccinia virus (VV). Recombinant BV-, VV-, and AV-GA733 induced antigen-specific cytotoxic antibodies and proliferative and delayed-type hypersensitive lymphocytes. However, only the AV recombinant induced antigen-specific cytolytic T lymphocytes and regression of established tumors. Cured mice were protected against challenge with antigen-negative tumors, indicating antigen spreading of immune responses. In a model of active immunotherapy against the murine homologue of the human GA733 antigen, murine epithelial glycoprotein (mEGP), BV-derived mEGP protein in various adjuvants did not protect mice against a challenge with mEGP-positive tumors. AV mEGP, only when combined with interleukin-2, significantly inhibited growth of established mEGP-positive tumors. This is in contrast to the same vaccine expressing the human antigen that was effective without interleukin-2. AV GA733, in combination with interleukin-2, is a candidate vaccine for colorectal cancer patients.

Chemokine mRNA expression in the cauda equina of Lewis rats with experimental allergic neuritis

Chemokines play an important role in the migration of leukocytes to inflammatory sites. In this study, using the quantitative competitive reverse transcriptase PCR method, we analyzed sequential expression of certain chemokine mRNAs in the cauda equina (CE) of rats with experimental allergic neuritis (EAN). Interferon-gamma-inducible protein (IP)-10, monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, the regulated upon activation normal T cell expressed and secreted chemokine (RANTES), and lymphotactin were analyzed on days 0 (pre-immunization), 7 (preclinical stage), 10 (disease onset), 13 (clinical progression), 17 (disease peak), as well as on days 20, 24, and 34 post-immunization (p.i.) (recovery). MCP-1 message increased at the preclinical stage and peaked at day 17 p.i. The increase in the early stage was not detected in other tissues, indicating peripheral nerve-specific upregulation. MIP-1alpha and IP-10 messages surged at day 13, then returned to low in the recovery stage. RANTES message increased at day 13 and peaked at day 17 p.i.; however, unlike other chemokines, it showed a second peak of expression on day 24. Lymphotactin message was undetectable at any time point. MCP-1 protein was detected immunohistologically in endothelial cells at day 7 p.i. The sequential expression of these chemokines in relation to the inflammatory process in the nerve leading to demyelination is discussed.