Onco-Circuit Addiction and Onco-Nutrient mTORC1 Signaling Vulnerability in a Model of Aggressive T Cell Malignancy

How genetic lesions drive cell transformation and whether they can be circumvented without compromising function of non-transformed cells are enduring questions in oncology. Here we show that in mature T cells-in which physiologic clonal proliferation is a cardinal feature- constitutive MYC transcription and Tsc1 loss in mice modeled aggressive human malignancy by reinforcing each other's oncogenic programs. This cooperation was supported by MYC-induced large neutral amino acid transporter chaperone SLC3A2 and dietary leucine, which in synergy with Tsc1 deletion overstimulated mTORC1 to promote mitochondrial fitness and MYC protein overexpression in a positive feedback circuit. A low leucine diet was therapeutic even in late-stage disease but did not hinder T cell immunity to infectious challenge, nor impede T cell transformation driven by constitutive nutrient mTORC1 signaling via Depdc5 loss. Thus, mTORC1 signaling hypersensitivity to leucine as an onco-nutrient enables an onco-circuit, decoupling pathologic from physiologic utilization of nutrient acquisition pathways.

Vocal Emotion Recognition in Autism: Behavioral Performance and Event-Related Potential (ERP) Response

Autistic youth display difficulties in emotion recognition, yet little research has examined behavioral and neural indices of vocal emotion recognition (VER). The current study examines behavioral and event-related potential (N100, P200, Late Positive Potential [LPP]) indices of VER in autistic and non-autistic youth. Participants (N = 164) completed an emotion recognition task, the Diagnostic Analyses of Nonverbal Accuracy (DANVA-2) which included VER, during EEG recording. The LPP amplitude was larger in response to high intensity VER, and social cognition predicted VER errors. Verbal IQ, not autism, was related to VER errors. An interaction between VER intensity and social communication impairments revealed these impairments were related to larger LPP amplitudes during low intensity VER. Taken together, differences in VER may be due to higher order cognitive processes, not basic, early perception (N100, P200), and verbal cognitive abilities may underlie behavioral, yet occlude neural, differences in VER processing.

Reprogramming tumor-associated macrophages to outcompete endovascular endothelial progenitor cells and suppress tumor neoangiogenesis

Tumors develop by invoking a supportive environment characterized by aberrant angiogenesis and infiltration of tumor-associated macrophages (TAMs). In a transgenic model of breast cancer, we found that TAMs localized to the tumor parenchyma and were smaller than mammary tissue macrophages. TAMs had low activity of the metabolic regulator mammalian/mechanistic target of rapamycin complex 1 (mTORC1), and depletion of negative regulator of mTORC1 signaling, tuberous sclerosis complex 1 (TSC1), in TAMs inhibited tumor growth in a manner independent of adaptive lymphocytes. Whereas wild-type TAMs exhibited inflammatory and angiogenic gene expression profiles, TSC1-deficient TAMs had a pro-resolving phenotype. TSC1-deficient TAMs relocated to a perivascular niche, depleted protein C receptor (PROCR)-expressing endovascular endothelial progenitor cells, and rectified the hyperpermeable blood vasculature, causing tumor tissue hypoxia and cancer cell death. TSC1-deficient TAMs were metabolically active and effectively eliminated PROCR-expressing endothelial cells in cell competition experiments. Thus, TAMs exhibit a TSC1-dependent mTORC1-low state, and increasing mTORC1 signaling promotes a pro-resolving state that suppresses tumor growth, defining an innate immune tumor suppression pathway that may be exploited for cancer immunotherapy.

Reprogramming tumour-associated macrophages to outcompete cancer cells

In metazoan organisms, cell competition acts as a quality control mechanism to eliminate unfit cells in favour of their more robust neighbours1,2. This mechanism has the potential to be maladapted, promoting the selection of aggressive cancer cells3-6. Tumours are metabolically active and are populated by stroma cells7,8, but how environmental factors affect cancer cell competition remains largely unknown. Here we show that tumour-associated macrophages (TAMs) can be dietarily or genetically reprogrammed to outcompete MYC-overexpressing cancer cells. In a mouse model of breast cancer, MYC overexpression resulted in an mTORC1-dependent 'winner' cancer cell state. A low-protein diet inhibited mTORC1 signalling in cancer cells and reduced tumour growth, owing unexpectedly to activation of the transcription factors TFEB and TFE3 and mTORC1 in TAMs. Diet-derived cytosolic amino acids are sensed by Rag GTPases through the GTPase-activating proteins GATOR1 and FLCN to control Rag GTPase effectors including TFEB and TFE39-14. Depletion of GATOR1 in TAMs suppressed the activation of TFEB, TFE3 and mTORC1 under the low-protein diet condition, causing accelerated tumour growth; conversely, depletion of FLCN or Rag GTPases in TAMs activated TFEB, TFE3 and mTORC1 under the normal protein diet condition, causing decelerated tumour growth. Furthermore, mTORC1 hyperactivation in TAMs and cancer cells and their competitive fitness were dependent on the endolysosomal engulfment regulator PIKfyve. Thus, noncanonical engulfment-mediated Rag GTPase-independent mTORC1 signalling in TAMs controls competition between TAMs and cancer cells, which defines a novel innate immune tumour suppression pathway that could be targeted for cancer therapy.

Postradioiodine Graves' management: The PRAGMA study

OBJECTIVE

Thyroid status in the months following radioiodine (RI) treatment for Graves' disease can be unstable. Our objective was to quantify frequency of abnormal thyroid function post-RI and compare effectiveness of common management strategies.

DESIGN

Retrospective, multicentre and observational study.

PATIENTS

Adult patients with Graves' disease treated with RI with 12 months' follow-up.

MEASUREMENTS

Euthyroidism was defined as both serum thyrotropin (thyroid-stimulating hormone [TSH]) and free thyroxine (FT4) within their reference ranges or, when only one was available, it was within its reference range; hypothyroidism as TSH ≥ 10 mU/L, or subnormal FT4 regardless of TSH; hyperthyroidism as TSH below and FT4 above their reference ranges; dysthyroidism as the sum of hypo- and hyperthyroidism; subclinical hypothyroidism as normal FT4 and TSH between the upper limit of normal and <10 mU/L; and subclinical hyperthyroidism as low TSH and normal FT4.

RESULTS

Of 812 patients studied post-RI, hypothyroidism occurred in 80.7% and hyperthyroidism in 48.6% of patients. Three principal post-RI management strategies were employed: (a) antithyroid drugs alone, (b) levothyroxine alone, and (c) combination of the two. Differences among these were small. Adherence to national guidelines regarding monitoring thyroid function in the first 6 months was low (21.4%-28.7%). No negative outcomes (new-onset/exacerbation of Graves' orbitopathy, weight gain, and cardiovascular events) were associated with dysthyroidism. There were significant differences in demographics, clinical practice, and thyroid status postradioiodine between centres.

CONCLUSIONS

Dysthyroidism in the 12 months post-RI was common. Differences between post-RI strategies were small, suggesting these interventions alone are unlikely to address the high frequency of dysthyroidism.

Trends in mortality from aortic stenosis in Europe: 2000–2017

Background

Trends in mortality from aortic stenosis across Europe are not well understood, especially given the significant growth in transcatheter aortic valve replacement (TAVR) in the last 10 years.

Purpose

To describe trends in mortality from aortic stenosis in European countries from 2000 to 2017.

Methods

Age-standardised death rates were extracted from the World Health Organisation Mortality Database, using the International Classification of Diseases 10th edition code for non-rheumatic aortic stenosis for those aged &gt;45 years between 2000 and 2017. The UK and countries from the European Union with at least 1,000,000 inhabitants and at least 50% available datapoints over the study period were included: a total of 23 countries. Trends were described using Joinpoint regression analysis.

Results

No reductions in mortality were demonstrated across all countries 2000–2017 (Figure 1). Large increases in mortality were found for Croatia, Poland and Slovakia for both sexes (&gt;300% change). Mortality plateaued in Germany from 2008 in females and 2012 in males, whilst mortality in the Netherlands declined for both sexes from 2007. Mortality differences between the sexes were observed, with greater mortality for males than females across most countries.

Conclusions

Mortality from aortic stenosis has increased across Europe from 2000 to 2017. There are, however, sizable differences in mortality trends between Eastern and Western European countries. Significant plateauing or declining mortality was observed for recent years in countries with greater access to TAVR, whilst increasing trends were observed in countries with the least TAVR use. The need for health resource planning strategies to specifically target AS, particularly given the expected increase with aging populations, is highlighted.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Joinpoint regression analysis for trends in age-standardised death rates from non-rheumatic aortic stenosis for those aged &gt;45 years in Europe from 2000 to 2017. Clear squares indicate males; filled circles indicate females. The lines (dotted for males, solid for females) represent modelled trends based on joinpoint data.

Impact of early (&lt;24h) versus delayed (&gt;24h) intervention in patients with non ST segment elevation myocardial infarction (an observational study of 20882 patients)

Background

In patients presenting with non ST-segment elevation acute coronary syndromes (NSTE-ACS) an invasive approach has been shown to be superior to conservative management.

Purpose

We aimed to investigate the optimal timing of invasive coronary angiography and subsequent intervention.

Methods

We examined the impact ofearly (≤24h) versus delayed (&gt;24h) intervention in a large observational cohort of 20882 consecutive patients with acute NSTE myocardial infarction (NSTEMI) treated with PCI between 2005 and 2015 at 9 tertiary cardiac centers in London (UK) using Cox-regression analysis and propensity matching.

Results

Mean age was 64.5±12.7 years and 26.1% were females. A quarter (27.6%), were treated within 24h.Patients treated within 24h were slightly younger (62.8±12.8 vs. 65.2±12.6, p&lt;0.001), most commonly male (76% vs. 72.9%, p&lt;0.001) and were more frequently ventilated (2.3% vs. 1.4%, p&lt;0.001) and in cardiogenic shock (3.6% vs. 1.4%, p&lt;0.001) with dynamic changes on their ECG (84.5% vs. 76.1% p&lt;0.001). At a median follow up of 4.2 years (interquartile range 1.8 to 7) 17.7% of patients had died. Estimated 5-year survival in patients treated within 24h was 84.6% vs. 81% for those treated &gt;24h following their presentation (p&lt;0.001). This survival benefit remained following adjustment for confounders; HR (delayed vs. early management)1.11 (95% CI 1.003 to 1.23, p=0.046). In the propensity matched cohort of 4356 patients in each group, there remained a trend for higher survival in the early intervention group (p=0.061).

Conclusions

Notwithstanding the limitations of the retrospective design, this real-world cohort of NSTEMI patients suggests that an early intervention (≤24h) may improve mid term survival.

Figure 1

Funding Acknowledgement

Type of funding source: None

New onset left bundle branch block after transcatheter aortic valve implantation and the effect on long-term survival – a UK wide experience

Introduction

New onset left bundle branch block (LBBB) is the most common conduction disturbance associated with transcatheter aortic valve implantation (TAVI). It has been shown to adversely affect cardiac function and increase re-hospitalisation, although its impact on mortality remains contentious.

Methods

We conducted an observational cohort analysis of all TAVI procedures performed by 13 heart teams in the United Kingdom from inception of their structural programmes until 31st July 2013. The primary outcome was 1-year all-cause mortality. Secondary outcomes included left ventricular ejection fraction (LVEF) at 30 days and need for a post-TAVI permanent pacemaker (PPM).

Results

1785 patients were eligible for inclusion to the study. The primary analysis cohort was composed of 1409 patients with complete electrocardiographic (ECG) data pre- and post-TAVI. Pre-existing LBBB was present in 200 (14.2%) patients. New LBBB occurred in 323 (22.9%) patients post TAVI, which resolved in 99 (7%) patients prior to discharge. A balloon-expandable device was implanted in 968 (69%) patients, whilst 421 (30%) patients received a self-expandable valve. New LBBB was observed in 120 (12.4%) and 192 (45.6%) patients receiving a balloon- or self-expandable prosthesis respectively.

Overall 1-year all-cause mortality post TAVI was 18.7%. New onset LBBB was not associated with an increase in 1-year all-cause mortality (p=0.416). Factors that were associated with mortality included an increasing logistic EuroScore (p=0.05), history of previous balloon aortic valvuloplasty (p=0.001), renal impairment (p=0.003), previous myocardial infarction with pre-existing LBBB (p=0.028) and atrial fibrillation (p=0.039). Lower baseline peak and mean AV gradients were also associated with greater mortality at 1 year (p=0.001), likely reflecting underlying left ventricular dysfunction.

In the majority of patients, LVEF remained unchanged following TAVI. Interestingly, the presence or absence of new onset LBBB did not affect LVEF improvement at 30 days. 10% of patients required a PPM post TAVI. Predictors of PPM included new LBBB (OR 2.6, p&lt;0.001), pre-TAVI left ventricular systolic impairment (OR 1.2, p=0.037), a self-expandable device (p&lt;0.001), and pre-existing RBBB (OR 4.0, p&lt;0.001).

Conclusions

These findings suggest that new onset LBBB post TAVI does not increase mortality at 1 year or adversely affect LVEF at 30 days.

Funding Acknowledgement

Type of funding source: None

P6516The association between prior coronary artery bypass graft surgery and outcome after percutaneous coronary intervention (PCI): an observational study of 123,780 patients

Background

Limited information exists regarding procedural success and clinical outcomes in patients with previous CABG undergoing percutaneous coronary intervention (PCI). We sought to compare outcomes in patients undergoing PCI with or without previous coronary artery bypass grafts (CABG).

Methods

This was an observational cohort study of 123,780 consecutive PCI procedures from the Pan-London (United Kingdom) PCI registry, from January 2005 to December 2015. The primary end-point was all-cause mortality at a median follow-up of 3.0 years (interquartile range 1.2–4.6 years).

Results

12,641 (10.2%) patients had a history of previous CABG, of whom 29.3% (n=3,703) underwent PCI to native vessels and 70.7% (n=8,938) to bypass grafts. There were significant differences in the demographic, clinical, and procedural characteristics of these groups. The risk of mortality during follow-up was significantly higher in patients with prior CABG (23.2%) (p=0.0005) compared to patients with no history of prior CABG (12.1%) and was seen for patients who underwent either native vessel (20.1%) or bypass graft PCI (24.2%, p<0.0001). However, after adjustment for baseline characteristics, there was no significant difference in outcomes seen between the groups when PCI was performed in native vessels in patients with previous CABG (HR 1.02, 95% CI 0.77–1.34; P=0.89) but a significant increase in mortality among patients with PCI to bypass grafts (HR 1.33 95% CI 1.03–1.71, P=0.026). This was seen after multivariate adjustment and propensity matching.

Figure 1. Kaplan-Meier Curves

Conclusion

Patients with prior CABG are older, with a greater comorbid burden and more complex procedural characteristics, but after adjustment for these differences clinical outcomes are similar to patients undergoing PCI without prior CABG. In these patients, native vessel PCI was associated with better outcomes compared to the treatment of vein grafts.

Probability-driven 3D pharmacophore mapping of antimycobacterial potential of hybrid molecules combining phenylcarbamoyloxy and N-arylpiperazine fragments

The current study examines in silico characterization of the structure-inhibitory potency for a set of phenylcarbamic acid derivatives containing an N-arylpiperazine scaffold, considering the electronic, steric and lipophilic properties. The main objective of the ligand-based modelling was the systematic study of classical comparative molecular field analysis (CoMFA)/comparative molecular surface analysis (CoMSA) performance for the modelling of in vitro efficiency observed for these phenylcarbamates, revealing their inhibitory activities against a virulent Mycobacterium tuberculosis H₃₇R_v strain. We compared the findings of efficiency modelling produced by a standard 3D methodology (CoMFA) and its neural counterparts (CoMSA) regarding multiple training/test subsets and variables used. Moreover, systematic space inspection, splitting values into the analysed training/test subsets, was performed to monitor statistical estimator performance while mapping the probability-driven pharmacophore pattern. Consequently, a 'pseudo-consensus' 3D-quantitative structure-activity relationship (3D-QSAR) approach was applied to retrieve an 'average' pharmacophore hypothesis by the investigation of the most densely populated training/test subpopulations to specify the potentially important factors contributing to the inhibitory activity of phenylcarbamic acid analogues. In addition, examination of descriptor-based similarity with a principal component analysis (PCA) procedure was employed to visualize noticeable variations in the performance of these molecules with respect to their structure and activity profiles.

Endoscopic lumbar discectomy under local anesthesia may be an alternative to microdiscectomy: A single centre's experience using the far lateral approach

OBJECTIVES

Since the turn of the century, minimally invasive surgery has become increasingly widespread. Discectomy surgery has evolved from wide open to microscopic and now endoscopic. This study aims to demonstrate that transforaminal endoscopic discectomy is an alternative and safe approach for degenerative disk surgery.

PATIENTS AND METHODS

Two year retrospective assessments of patients who underwent transforaminal endoscopic discectomy at a tertiary neurosurgical center in the United Kingdom by a single surgeon. Under strict confidentiality, data was collected from online patient data and PACS systems. Patient feedback was achieved using phone call follow up and clinic appointments. Standard statistical analysis was performed.

RESULTS

201 patients had endoscopic discectomy and the mean age was 41 years. Male:female ratio was 1.3:1.0. Mean time of onset of symptoms was 5.5 months and the most common level was L4/5 (53%). All endoscopic discectomies were performed under local anesthesia. Theater time was on average 110 min. 10 patients were lost to follow up. 95% of patients were discharged within 7h post operatively. Visual acuity score of the pain dropped from an average of 7/10 pre-operatively to 0-1/10 in 95% of patients two weeks post operatively. 87% patients went back to their normal daily activities within two weeks. There were no cases of CSF leak, hematoma formation or wound infection. 1% of patients developed a nerve root injury. 6% of patients had recurrent herniation and require microdiscectomy.

CONCLUSION

Endoscopic discectomy can be an alternative approach to microdiscectomy. While it can take more expertise to perform endoscopic discectomy, our data shows that the far lateral endoscopic discectomy using the TESSYS technique has comparable outcomes to microdiscectomy.

Pegfilgrastim in colorectal cancer (CRC) patients (pts) receiving every-two-week (Q2W) chemotherapy (CT): Long-term results from a phase II, randomized, controlled study

4072

Background: Survival in advanced CRC is prolonged by adding oxaliplatin (Ox) and/or irinotecan (Iri) to Q2W 5-fluorouracil/leucovorin (5FU/LV). Combination therapy, however, has a higher incidence of febrile neutropenia (FN) and related toxicities. This study evaluated pegfilgrastim dosing on day 4 of Q2W regimens in CRC. Here we present long-term follow-up of these pts. Methods: Advanced CRC pts were randomized (1:1) to pegfilgrastim 6mg or placebo, which was stratified by CT regimen received: FOIL, FOLFOX, or FOLFIRI. We previously reported grade 3/4 neutropenia (primary endpoint) in 43% placebo and 13% pegfilgrastim pts in the 4-cycle treatment phase (odds ratio = 0.19, 95% CI: 0.10–0.37; p < 0.0001). After end of treatment, pts were followed long term for ≤ 2 years (inclusive of ≤ 8 additional cycles) for serious adverse events (SAEs), overall survival (OS), and progression-free survival (PFS). Median follow-up time was 519 days. Kaplan-Meier methods estimated OS and PFS from study day 1. The study was not powered to detect PFS or OS differences between treatment groups. Results: Of 241 pts analyzed (123 pegfilgrastim, 118 placebo), 49% received FOLFOX, 26% FOLFIRI, and 25% FOIL. In the treatment period, 8% placebo and 2% pegfilgrastim pts had grade 3/4 FN ( Table ). Pegfilgrastim was well tolerated with no dose delays attributed to leukocytosis. Pegfilgrastim and placebo had similar PFS and OS ( Table ). No SAEs related to study drug were reported in the follow-up period. Conclusions: In this randomized, placebo-controlled study, pegfilgrastim significantly lowered neutropenic risk. Bone pain incidence in this CRC population was lower than in breast cancer pts treated with a taxane (Vogel J Clin Oncol 2005); the incidence in pegfilgrastim pts was modestly increased over placebo. Leukocytosis was not a concern despite the 11-day dosing interval. Long-term results suggest similar PFS and OS in the pegfilgrastim and placebo pts in this CRC study.

[Table: see text]

[Table: see text]

Neurodegeneration associated with genetic defects in phospholipase A(2)

OBJECTIVE

Mutations in the gene encoding phospholipase A(2) group VI (PLA2G6) are associated with two childhood neurologic disorders: infantile neuroaxonal dystrophy (INAD) and idiopathic neurodegeneration with brain iron accumulation (NBIA). INAD is a severe progressive psychomotor disorder in which axonal spheroids are found in brain, spinal cord, and peripheral nerves. High globus pallidus iron is an inconsistent feature of INAD; however, it is a diagnostic criterion of NBIA, which describes a clinically and genetically heterogeneous group of disorders that share this hallmark feature. We sought to delineate the clinical, radiographic, pathologic, and genetic features of disease resulting from defective phospholipase A(2).

METHODS

We identified 56 patients clinically diagnosed with INAD and 23 with idiopathic NBIA and screened their DNA for PLA2G6 mutations.

RESULTS

Eighty percent of patients with INAD had mutations in PLA2G6, whereas mutations were found in only 20% of those with idiopathic NBIA. All patients with two null mutations had a more severe phenotype. On MRI, nearly all mutation-positive patients had cerebellar atrophy, and half showed brain iron accumulation. We observed Lewy bodies and neurofibrillary tangles in association with PLA2G6 mutations.

CONCLUSION

Defects in phospholipase A(2) lead to a range of phenotypes. PLA2G6 mutations are associated with nearly all cases of classic infantile neuroaxonal dystrophy but a minority of cases of idiopathic neurodegeneration with brain iron accumulation, and genotype correlates with phenotype. Cerebellar atrophy predicts which patients are likely to be mutation-positive. The neuropathologic changes that are caused by defective phospholipase A(2) suggest a shared pathogenesis with both Parkinson and Alzheimer diseases.

Physiology and pathophysiology of liver inflammation, damage and repair

The liver is the largest organ of the body. It is located between the portal and the general circulation, between the organs of the gastrointestinal tract and the heart. The main function of the liver is to take up nutrients, to store them, and to provide nutrients to the other organs. At the same time has the liver to take up potentially damaging substances like bacterial products or drugs delivered by the portal blood or microorganisms, which reach the circulation. The liver is not only an important power and sewage treatment plant of the body. In fact, the liver is probably the best example for a cheap recycling system. Both parenchymal and nonparenchymal liver cells participate in the clearance activities. The function of the liver as clearance organ, however, harbors the danger that the substances that should be degraded and/or eliminated lead to tissue damage. Thus, effective defense mechanisms are necessary. Among the nonparenchymal cells Kupffer cells, sinusoidal endothelial cells, and natural killer (NK) lymphocytes exert cellular defense functions for the whole body but also for the liver itself. Furthermore, each cell type of the liver, including the hepatocytes, possesses its own defense apparatus.

Panitumumab activity in metastatic colorectal cancer (mCRC) patients (pts) with low or negative tumor epidermal growth factor receptor (EGFr) levels: An updated analysis

4082

Background: Panitumumab, a fully human monoclonal antibody against EGFr, is approved for EGFr-expressing mCRC pts with disease progression (PD) on or after fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy. However, the predictive value of EGFr tumor-membrane staining as measured by immunohistochemistry (IHC) is undetermined. Methods: This multicenter, single arm, phase 2 study enrolled pts with documented PD during or after fluoropyrimidine and adequate doses of irinotecan and oxaliplatin, and within 6 months after the most recent chemotherapy regimen (determined by an independent eligibility review committee [IERC]), 2–3 prior regimens, and low (1%-9%) or negative (<1%) EGFr tumor membrane staining (by IHC). Pts received panitumumab 6mg/kg Q2W until PD or intolerability. Tumor assessments (modified WHO, blinded central review) were performed every 8 weeks until PD or discontinuation. Endpoints were objective response rate (ORR) through wk 16 (+ =4 wk confirmation; primary), overall ORR, response duration, progression-free survival (PFS), and safety (secondary). Results: In this interim analysis, 91 pts had =20 wks of potential follow-up and comprised the IERC efficacy set; 118 pts comprised the evaluable safety set (=20 wks potential follow-up). In the IERC efficacy set, 57% were male, 86% were white, and median age (range) was 61 (26–85) years. ORR through week 16 is shown; overall ORR was the same ( Table ). The most common adverse events (all, grade 3/4) were dermatitis acneiform (72%, 6%), erythema (69%, 6%), pruritus (65%, 4%), and hypomagnesaemia by lab values (53%, 10%). Four pts (3%) had an infusion reaction per investigator (1 was grade 3). Conclusions: This analysis confirms earlier findings that panitumumab has anti-tumor activity in pts with low or undetectable EGFr tumor membrane levels as measured by IHC. This study has completed enrollment, and updated data will be presented.

[Table: see text]

No significant financial relationships to disclose.

Potentiation of in vivo neuroprotection by BclXL and GDNF co-expression depends on post-lesion time in deafferentiated CNS neurons

To elucidate effective and long-lasting neuroprotective strategies, we analysed a combination of mitochondrial protection and neurotrophic support in two well-defined animal models of neurodegeneration, traumatic lesion of optic nerve and complete 6-hydroxydopamine (6-OHDA) lesion of nigrostriatal pathway. Neuroprotection by BclX(L), Glial cell line-derived neurotrophic factor (GDNF) or BclX(L) plus GDNF co-expression were studied at 2 weeks and at 6-8 weeks after lesions. In both lesion paradigms, the efficacy of this combination approach significantly differed depending on post-lesion time. We show that BclX(L) expression is more important for neuronal survival in the early phase after lesions, whereas GDNF-mediated neuroprotection becomes more prominent in the advanced state of neurodegeneration. BclX(L) expression was not sufficient to finally inhibit degeneration of deafferentiated central nervous system neurons. Long-lasting GDNF-mediated neuroprotection depended on BclX(L) co-expression in the traumatic lesion paradigm, but was independent of BclX(L) in the 6-OHDA lesion model. The results demonstrate that neuroprotection studies in animal models of neurodegenerative diseases should generally be performed over extended periods of time in order to reveal the actual potency of a therapeutic approach.

Panitumumab antitumor activity in patients (pts) with metastatic colorectal cancer (mCRC) expressing low (1–9%) or negative (<1%) levels of epidermal growth factor receptor (EGFr)

3547

Background: Panitumumab is a fully human monoclonal antibody directed against EGFr. We investigated the antitumor activity of panitumumab in pts with mCRC who failed prior therapy and had low or negative EGFr tumor expression. Methods: In this multicenter, phase 2 study of 150 planned pts, pts had documentation of disease progression (PD) during or after adequate doses of fluoropyrimidine, irinotecan, and oxaliplatin (centrally confirmed refractory disease [CCRD]), 2–3 prior regimens, ECOG score 0–2, and low or negative EGFr staining (by IHC) in evaluable tumor cells. Pts received panitumumab at 6 mg/kg Q2W until PD or drug intolerability. Tumor assessments (modified WHO, blinded central review) were taken periodically from wk 8 until PD. Endpoints were objective response (OR) through wk 16 (+ ≥ 4 wk confirmation; primary) and OR throughout study, response duration, progression-free survival (PFS) time, survival time, and safety (secondary). Results: In this interim analysis (6/05), 88 pts were enrolled and had ≥ 1 dose of panitumumab (safety set); 23 pts had ≥ 20 wks before the cutoff and CCRD (efficacy set). The efficacy set consisted of 16M/7W, median age of 65 (range: 46, 85) yrs, 83% white, 100% with ECOG ≤ 1, 74% colon cancer and 26% rectal cancer; all received ≥ 2 prior regimens (equivalent characteristics for safety set). 2/11 (18%) pts with EGFr-negative tumors and 1/12 (8%) with low EGFr staining had a partial response. Duration was up to 16 wks. 7/23 (30%) of all pts had SD. Median (95% CI) PFS was 7.9 (7.0, 23.0) wks. In the safety set, all pts had a treatment-related adverse event; 19% grade (gr) 3; 2% gr 4. Integument and eye toxicities were: 92% skin, 17% eye, 28% nail, 8% hair, and 2% chelitis. 20 (23%) had diarrhea (1 gr 3); 7 (8%) had hypomagnesemia (2 gr 3/4). Three pts had an infusion reaction-1 gr 3 (led to panitumumab discontinuation) and 2 gr 1/2. In 65 pts with both a baseline and post-baseline sample, no human anti-human antibodies to panitumumab were detected. Updated data will be presented. Conclusions: Responses to panitumumab were seen in pts with mCRC with both low and negative EGFr levels. Efficacy appears similar to that in other studies with panitumumab in pts with higher EGFr tumor levels.

[Table: see text]

Treatment options for von Hippel-Lindau's haemangioblastomatosis: the role of gamma knife stereotactic radiosurgery

Haemangioblastomas secondary to von Hippel-Lindau (VHL) disease can be difficult to manage surgically, which has lead to an interest in the use of stereotactic radiosurgery. Retrospectively reviewed here are 30 tumours treated in 14 patients with a mean +/- SD follow-up of 34 +/- 24 months. During this time, three of the 14 patients (21%) died, two of generalized progressive disease. Before radiosurgery, the median time between interventions for cranial haemangioblastomas was 3 years (mean 3.9 +/- 5.0 years). After radiosurgery, the tendency for cranial disease progression was similar, 50% of patients developing further disease by 5 years. Local tumour control was achieved in the majority of cases and estimates of this are included. Radiosurgery is a useful palliative measure controlling the majority of haemangioblastomas, although its efficacy in these patients is limited by the tendency of further disease to develop or progress intracranially.