Abstract 5616: Soluble, high affinity TCRs fused to anti-CD3 redirect T cells to kill cancer cells presenting MAGE-A3 and NY-ESO antigens

In the last decade, major efforts in the fight against cancer have focussed on galvanising the adaptive immune system to kill tumours. Many of these endeavours are based on the development and clinical use of monoclonal antibodies (mAb) which are the most successful class of immune modulating agent identified to date. However, while mAbs show promise against certain cancers, their specificity is limited to integral membrane proteins; this hinders their extensive development for the purposes of targeting cancer cells.

In contrast to mAbs, T cell receptors (TCRs) recognise peptides bound to major histocompatibility complex class I (MHC I) molecules. These peptides are derived from endogenously processed proteins, and therefore represent a different repertoire of targets to those recognised by mAbs. This alternate spectrum of antigens provides the potential to target cancers using an untapped source of well-validated epitopes. Naturally occurring TCRs, however, have relatively low affinities for their antigen compared to antibody binding. Advances in engineering techniques have allowed the generation of high affinity monoclonal TCRs (mTCRs) with picomolar affinities for their antigen. Using targeted mutagenesis and phage display, we have generated a number of soluble, high affinity mTCRs specific for several reported tumour-associated antigens. Through mTCR fusion to an anti-CD3 single chain variable fragment (scfv), we produced bifunctional proteins that redirect T cell immune specificity. These novel proteins are termed ImmTACs (Immune-mobilising mTCRs Against Cancer). We present data demonstrating the potential of two such ImmTAC molecules, NY-ESO-ImmTAC and MAGE-A3-ImmTAC, to treat certain cancers. NY-ESO1 and MAGE-A3 are both cancer testes antigens and therefore represent potentially very clean molecular targets. We demonstrate that both NY-ESO-ImmTAC and MAGE-A3-ImmTAC are capable of potently redirecting unstimulated peripheral blood mononuclear cells (PBMC) or CD8+ T cells against multiple myeloma, colorectal carcinoma and non-small cell lung cancer cell lines despite the presentation of extremely low antigen numbers (<100 epitopes/cell) on the surface of these cells. ImmTAC-redirected T cells respond with multiple effector functions including the production of granzyme B, IFNγ and IL-2, resulting in a high level of antigen-specific cancer cell killing over the course of 24 hours. The mechanism of killing is at least partly contributed by the caspase-3/7 apoptotic pathway. We also show that NY-ESO-ImmTAC and MAGE-A3-ImmTAC were inert by all our measures in the presence of normal primary cells including melanocytes, hepatocytes and astrocytes. Thus both MAGE-A3 and NY-ESO-ImmTACs possess the potential to be highly specific, potent cancer immunotherapies offering a targeting and therapeutic approach distinct from any other biologic in development.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5616.

An Australian experience of retrievable inferior vena cava filters in patients with increased risk of thromboembolic disease

AIM

Pulmonary embolism (PE) is a common cause of death and morbidity. Anticoagulant therapy reduces the risk of PE but is associated with bleeding. Inferior vena caval (IVC) filters protect against PE but have an increased long term risk of deep vein thrombosis (DVT). Temporary IVC filters allow protection against PE during high risk situations and may be later removed avoiding the need for long term anticoagulation.

METHODS

We present our experience with the Recovery (Bard, Tempe, AZ) and Tulip (Cook, Bloomington, IN) optionally retrievable filters.

RESULTS

Retrievable filters were planned for 121 patients. Mean age: 58.8 years; 72 male. The indications included: Established venous thromboembolism (VTE) and contraindication to anticoagulation; high risk of VTE and need for surgery with high risk of bleeding; VTE extension despite anti-coagulation. A retrievable filter was placed without significant incident in 113 patients. There were two proven cases of PE. In total there were 27 deaths of patients during the period of their follow up. There was 1 death related to confirmed filter migration. There was 1 sudden unexplained death in a patient with suspected malignancy. Filter removal was attempted in 58 cases at a mean of 44 days and was performed successfully in 52. Thromboembolus was found in the retrieved filter in 30 cases but did not prevent removal in 29.

CONCLUSION

Retrievable IVC Filters are safe and effective in preventing PE in high risk patients. We have demonstrated success in retrieving filters up to 182 days following insertion, avoiding the need for long term anticoagulation.

Invasive group B streptococcal disease in the elderly, Minnesota, USA, 2003-2007

In Minnesota, incidence of invasive group B streptococcal disease was 3 times greater in older adults in long-term care facilities than in older adults in community settings (67.7/100,000 vs. 21.4/100,000) during 2003–2007. The overall case-fatality rate was 6.8%, and concurrent conditions were common among both groups.

Internalized weight stigma and its ideological correlates among weight loss treatment seeking adults

There are significant economic and psychological costs associated with the negative weight-based social stigma that exists in American society. This pervasive anti-fat bias has been strongly internalized among the overweight/obese. While the etiology of weight stigma is complex, research suggests that it is often greater among individuals who embrace certain etiological views of obesity or ideological views of the world. This investigation examined 1) the level of internalized weight stigma among overweight/obese treatment seeking adults, and 2) the association between internalized weight stigma and perceived weight controllability and ideological beliefs about the world ('just world beliefs', Protestant work ethic). Forty-six overweight or obese adults (BMI >or=27 kg/m2) participating in an 18- week behavioral weight loss program completed implicit (Implicit Associations Test) and explicit (Obese Person's Trait Survey) measures of weight stigma. Participants also completed two measures of ideological beliefs about the world ("Just World Beliefs", Protestant Ethic Scale) and one measure of beliefs about weight controllability (Beliefs about Obese Persons). Significant implicit and explicit weight bias was observed. Greater weight stigma was consistently associated with greater endorsement of just world beliefs, Protestant ethic beliefs and beliefs about weight controllability. Results suggest that the overweight/obese treatment seeking adults have internalized the negative weight-based social stigma that exists in American society. Internalized weight stigma may be greater among those holding specific etiological and ideological beliefs about weight and the world.

Concentration of antibodies to extractable nuclear antigens and disease activity in systemic lupus erythematosus

A hallmark of systemic lupus erythematosus (SLE) is the production of autoantibodies directed against intracellular antigens. Antibodies to double stranded DNA (dsDNA) are most closely associated with the clinical manifestations of the condition and appear to have a direct role in pathogenesis. On the contrary, the relationship between disease activity in SLE and anti-extractable nuclear antigen (ENA) antibodies has not been well demonstrated. Despite this, commercial assays for the quantification of anti-ENA antibodies are now widely available, although their usefulness in clinical practice is not known. The aim of this study was to investigate whether there is an association between disease activity in SLE and concentrations of individual anti-ENA antibodies. A prospective 2-year study of 45 patients with SLE, known to be positive for at least one anti-ENA antibody, was performed. Disease activity was assessed using the SLE Disease Activity Index (SLEDAI). Anti-ENA antibodies were quantified using a commercial antibody detection system. A total of 45 patients were studied over a 2-year period (median number of assessments 5, range 2–9). Of them 29 patients were positive for Ro, 8 for La, 9 for Sm and 27 for RNP antibodies. In the population as a whole, there was a weak relationship between peak SLEDAI score and anti-Sm concentration ( r = 0.57, NS), but no relation with the other anti-ENA antibodies. In a small number of patients, there appeared to be either a positive (Ro, Sm) or negative (La, Sm, RNP) association between ENA antibody concentration and disease activity over time; however, this was not apparent for the majority of individuals. These results show that in SLE, clinically significant changes in disease activity do not correlate well with concentrations of anti-ENA antibodies, either within the population as a whole or on an individual basis. Repeated quantitative measurement of anti-ENA antibodies does not therefore appear to provide useful additional information in assessing disease activity in SLE. The widespread application of commercial quantitative assays to routine clinical practice is not recommended.

Class I PI3 kinase inhibition by the pyridinylfuranopyrimidine inhibitor PI-103 enhances tumor radiosensitivity

Cell signaling initiated at the epidermal growth factor receptor (EGFR), RAS oncoproteins, or PI3K contributes to a common pathway that promotes tumor survival after radiation-induced DNA damage. Inhibition of signaling at the level of EGFR, RAS, and PI3K has been tested, but clinical applicability has been shown only at the level of the EGFR or by inhibiting RAS indirectly with prenyltransferase inhibitors. Inhibition of PI3K with LY294002 or wortmannin lacks specificity and has shown unacceptable toxicity in preclinical studies. We previously showed that inhibiting class I PI3K expression with siRNA resulted in enhanced radiation killing of tumor cells. Here, we tested the possibility of achieving specific tumor cell radiosensitization with a pharmacologic inhibitor of class I PI3K, the pyridinylfuranopyrimidine inhibitor PI-103. Our results show that inhibiting PI3K activity reduces phosphorylation of AKT at serine 473. Reduced survival is seen in cells with AKT activation and seems preferential for tumor cells over cells in which AKT activity is not elevated. Reduced survival is accompanied by persistence of DNA damage as evidenced by persistence of gamma H2AX and Rad 51 foci after irradiation in the presence of the inhibitor. Reduced survival does not result from cell cycle redistribution during the PI-103 treatment intervals tested, although combining PI-103 treatment with radiation enhances the G(2)-M delay observed after irradiation. These results indicate that pharmacologic inhibitors with enhanced specificity for class I PI3K may be of benefit when combined with radiotherapy.

Initial Australian experience with the recovery inferior vena cava filter in patients with increased risk of thromboembolic disease

Inferior vena cava (IVC) filters are an alternative treatment in venous thromboembolism where there are contraindications to anticoagulation. There are, however, concerns about the long-term safety of permanent IVC filters. Often, the period of risk from anticoagulation therapy is short, which supports the use of non-permanent IVC filters. In this series, 54 Recovery Filters (Bard, Tempe, AZ, USA) were placed since its approval for use in Australia in March 2004 (approved for removal up to 160 days after insertion). The most common indication for filter placement in this series was established thromboembolic disease with a temporary contraindication to anticoagulation. Twenty-two filters were successfully retrieved without complication. In one case, it was not possible to retrieve the filter because of extensive contained thrombus. No complication was experienced at filter placement or retrieval; however, a fatal complication occurred as a result of filter migration. Mean time from placement to retrieval was 48 days (range 7-90 days). We describe methods we found useful at filter retrieval to overcome filter tilting.

Minimally invasive surgery fellows would perform a wider variety of cases in their "ideal" fellowship

BACKGROUND

With the increase in minimally invasive surgery (MIS) fellowships, the concept of the ideal and standardized training curriculum is emerging in importance. The authors hypothesize that the procedure mix in current MIS training is different from what current MIS fellows would expect for their "ideal" fellowship.

METHODS

An anonymous survey of current MIS fellows examined their perceptions of the case diversity and volume they expect to perform in their fellowships as compared with an ideal fellowship. Differences between expected and ideal case volume were analyzed using Wilcoxon tests.

RESULTS

A total of 32 questionnaires were returned. Current MIS fellows believe their expected training will exceed the ideal volume of laparoscopic cholecystectomies (p = 0.002). They believe their expected training is equivalent to ideal training in laparoscopic gastric bypass, ventral herniorraphy, inguinal herniorraphy, antireflux procedures, appendectomy, and diagnostic endoscopy (nonsignificant difference). However, current expected training falls short of their "ideal" case volume in laparoscopic gastric banding, colectomy, common bile duct exploration, gastrectomy, esophagectomy, splenectomy, adrenalectomy, hepatectomy, nephrectomy, and pancreatectomy (p < 0.05). The current MIS fellows also expect that their thoracoscopic, therapeutic endoscopy, and robotic procedure volume will be less than "ideal" (p < 0.05).

CONCLUSION

In 13 of 20 procedure types, current MIS fellows expect to perform a smaller case volume than in an "ideal" fellowship. The ideal case volume in the MIS fellowship curriculum needs to be defined better.