SARS-COV-2 INFECTION AND INVOLVEMENT OF PERIPHERAL NERVOUS SYSTEM: A CASE SERIES OF CARPAL TUNNEL SYNDROME AGGRAVATION OR NEW ONSET WITH COVID-19 DISEASE AND A REVIEW OF LITERATURE

COVID-19 may be asymptomatic or have a typical presentation with fever, cough, anosmia, lymphocytopenia. In some cases, it occurs with a "chimeric" presentation, with more subtle and ambiguous symptoms which may be initially misdiagnosed and are referred to in long covid condition. A possible central and peripheral nervous system involvement has been recognized. We present our experience and review the literature about association between carpal tunnel syndrome (CTS) and hand's arthritis presenting a case series of patients who firmly state that their condition of CTS arised or got worse during a typical presentation of COVID-19. The outbreak of COVID-19 has resulted in significant global healthcare implications. While the respiratory manifestations of COVID-19 have been widely studied, there is emerging evidence suggesting potential associations between COVID-19 and various other health conditions. This review of the literature aims to investigate the potential relationship between COVID-19 and the development or exacerbation of CTS. By synthesizing the available literature on this topic, we aim to provide a comprehensive overview of the current knowledge and enhance our understanding of the potential implications of COVID-19 on CTS. Case series: In this article we report 13 cases of typical presentations of COVID-19 with fever, myalgia, and respiratory system involvement, with a simultaneous aggravation of the median nerve pre-existing neuralgia and some cases that developed a median nerve neuralgia during COVID-19, which came to the attention of the hand surgeon. Some cases had stable symptomatic CTS and were on waiting list for surgical carpal tunnel release, some cases were previously asymptomatic and developed a median nerve neuralgia during COVID-19. All patients referred to a rapid worsening of acral paraesthesia and neuralgic pain of the same quality of CTS and in the median nerve topography. Some patients developed typical COVID-19 symptoms and died; the others were surgically treated. CTS could be an atypical presentations of COVID-19 or a condition of long-covid disease and clinical and epidemiological significance needs to be fully studied. We presented cases of worsening of the median nerve neuralgia which presented among other symptoms of COVID infection. We conclude a causal relation may exist and needs to be further investigated.

Serum calcium levels are associated with cognitive function in hypoparathyroidism: a neuropsychological and biochemical study in an Italian cohort of patients with chronic post-surgical hypoparathyroidism

PURPOSE

Hypoparathyroidism (HypoPT) is a rare endocrine disease and conventional therapy is based on calcium and vitamin D analogues. Conventional therapy does not restore calcium homeostasis and patients complain with neuropsychological symptoms, which have been evaluated with nonspecific self-administered questionnaires. This study aims to evaluate cognitive functions of patients with chronic post-surgical (PS)-HypoPT compared to a control population, using a standardized neuropsychological approach and evaluating the relationship with serum calcium (Alb-Ca).

METHODS

Observational, monocentric study on 33 patients with PS-HypoPT and 24 controls, in whom biochemical testing and a standardized neuropsychological assessment by a trained psychologist were performed.

RESULTS

In patients with PS-HypoPT, low Alb-Ca correlated with a worse performance on semantic memory abilities and executive function, as suggested by a significant inverse correlation between Alb-Ca and Trail Making Test A (TMT-A) scores (r = - 0.423; p = 0.014) and by a positive correlation with Semantic Fluency Test scores (SF)(r = 0.510; p = 0.002). PS-HypoPT patients with Alb-Ca ≤ 8.9 mg/dl had a significantly lower test performance compared with PS-HypoPT patients with Alb-Ca > 8.9 mg/dl, both at the TMT-A test (mean score: 34.53-18.55; p < 0.0001) and at SF test (mean score: 41.94-48.68; p = 0.01) and also a significantly lower test performance compared with control patients' group at TMT-A (mean score: 34.53-25.5; p = 0.0057).

CONCLUSIONS

Patients with chronic PS-HypoPT in conventional therapy do not show a severe cognitive impairment; however, cognitive functions namely visuo-spatial attention, executive function and semantic memory appear to be modulated by Alb-Ca and impaired by its low levels.

Renal complications and quality of life in postsurgical hypoparathyroidism: a case-control study

PURPOSE

Conventional therapy (calcium and activated vitamin D) does not restore calcium homeostasis in patients with chronic hypoparathyroidism (HypoPT) and is associated with renal complications and reduced quality of life (QoL). The aim of this study was to evaluate in a case-control, cross-sectional study, the rate of renal complications and QoL in two sex- and age-matched cohort of patients with differentiated thyroid cancer with (n = 89) and without (n = 89) chronic post-operative HypoPT (PoHypoPT) and their relationship with the biochemical control of the disease.

METHODS

Serum and urinary parameters, renal ultrasound and QoL were assessed by SF-36 and WHO-5 questionnaires.

RESULTS

Forty-three (48.3%) PoHypoPT patients reported symptoms of hypocalcemia. Twenty-six (29.2%) patients were at target for all 6 parameters, 46 (51.6%) for 5. The most frequently unmet targets were gender-specific 24-h urinary calcium (44.9%) and serum calcium (37.1%). Serum phosphate, magnesium and 25(OH)D were in the normal range in > 90% of patients. Renal calcifications were found in 26 (29.2%) patients, with no correlation with 24-h urinary calcium. eGFR did not differ between patients and controls. Conversely, patients had a significant higher rate of renal calcifications and a lower SF-36, but not WHO-5, scores. SF-36 scores did not differ between PoHypoPT patients who were, or not, hypocalcemic.

CONCLUSIONS

Our study shows that the rate of renal calcifications was higher in patients with PoHypoPT than in those without. This finding, together with the reduced QoL and the presence of hypocalcemic symptoms in about half patients, underscores that the treatment of chronic HypoPT with conventional therapy is suboptimal.

Optimized EGFR Blockade Strategies in EGFR Addicted Gastroesophageal Adenocarcinomas

PURPOSE

Gastric and gastroesophageal adenocarcinomas represent the third leading cause of cancer mortality worldwide. Despite significant therapeutic improvement, the outcome of patients with advanced gastroesophageal adenocarcinoma is poor. Randomized clinical trials failed to show a significant survival benefit in molecularly unselected patients with advanced gastroesophageal adenocarcinoma treated with anti-EGFR agents.

EXPERIMENTAL DESIGN

We performed analyses on four cohorts: IRCC (570 patients), Foundation Medicine, Inc. (9,397 patients), COG (214 patients), and the Fondazione IRCCS Istituto Nazionale dei Tumori (206 patients). Preclinical trials were conducted in patient-derived xenografts (PDX).

RESULTS

The analysis of different gastroesophageal adenocarcinoma patient cohorts suggests that EGFR amplification drives aggressive behavior and poor prognosis. We also observed that EGFR inhibitors are active in patients with EGFR copy-number gain and that coamplification of other receptor tyrosine kinases or KRAS is associated with worse response. Preclinical trials performed on EGFR-amplified gastroesophageal adenocarcinoma PDX models revealed that the combination of an EGFR mAb and an EGFR tyrosine kinase inhibitor (TKI) was more effective than each monotherapy and resulted in a deeper and durable response. In a highly EGFR-amplified nonresponding PDX, where resistance to EGFR drugs was due to inactivation of the TSC2 tumor suppressor, cotreatment with the mTOR inhibitor everolimus restored sensitivity to EGFR inhibition.

CONCLUSIONS

This study underscores EGFR as a potential therapeutic target in gastric cancer and identifies the combination of an EGFR TKI and a mAb as an effective therapeutic approach. Finally, it recognizes mTOR pathway activation as a novel mechanism of primary resistance that can be overcome by the combination of EGFR and mTOR inhibitors.See related commentary by Openshaw et al., p. 2964.

Hypercalciuria: its value as a predictive risk factor for nephrolithiasis in asymptomatic primary hyperparathyroidism?

CONTEXT

The latest guidelines of the 4th International Workshop on Asymptomatic Primary Hyperparathyroidism (aPHPT) reintroduced hypercalciuria (i.e. urinary calcium > 400 mg/day) as criterion for surgery. However, the value of hypercalciuria as a predictor of nephrolithiasis and the correct cut-off values still need to be confirmed.

OBJECTIVE

To evaluate the prevalence of silent kidney stones in a large series of patients with aPHPT and the sensibility, specificity and predictive value of different cut-off values of hypercalciuria in identifying patients with nephrolithiasis.

DESIGN

One hundred seventy-six consecutive patients with aPHPT were evaluated at our Institution by serum and urinary parameters and kidney ultrasound.

RESULTS

Silent nephrolithiasis was found in 38 (21.6%) patients. In the univariate and multivariate model, hypercalciuria was a predictor of nephrolithiasis using the criterion of 400 mg/24 h [(OR 2.30, (1.11-4.82) P = 0.025], 4 mg/kg/bw [OR 2.65, (1.14-6.25) P = 0.023], gender criterion [OR 2.79, (1.15-6.79) P = 0.023] and the cut-off value derived from the ROC analysis [(> 231 mg/24 h) OR 5.02 (1.68-14.97) P = 0.004]. Despite these several predictive criteria, however, hypercalciuria had a low positive predictive value (PPV), ranging from 27.4 to 32.7%.

CONCLUSIONS

Hypercalciuria is a predictor of nephrolithiasis, but its PPV is low.

Correction to: Whole exome sequencing in familial isolated primary hyperparathyroidism

Unfortunately, the 13th author name has been published incorrectly in the original publication.

Whole exome sequencing in familial isolated primary hyperparathyroidism

PURPOSE

Familial isolated hyperparathyroidism (FIHP) is a rare inherited disease accounting for 1% of all cases of primary hyperparathyroidism (PHPT). It is genetically heterogeneous being associated with mutations in different genes, including MEN1, CDC73, CASR, and recently GCM2. The aim of the study was to further investigate the molecular pathogenesis in Italian FIHP kindreds.

METHODS

We used whole exome sequencing (WES) in the probands of seven unrelated FIHP kindreds. We carried out a separate family-based exome analysis in a large family characterized by the co-occurrence of PHPT with multiple tumors apparently unrelated to the disease. Selected variants were also screened in 18 additional FIHP kindreds. The clinical, biochemical, and pathological characteristics of the families were also investigated.

RESULTS

Three different variants in GCM2 gene were found in two families, but only one (p.Tyr394Ser), already been shown to be pathogenic in vitro, segregated with the disease. Six probands carried seven heterozygous missense mutations segregating with the disease in the FAT3, PARK2, HDAC4, ITPR2 and TBCE genes. A genetic variant in the APC gene co-segregating with PHPT (p.Val530Ala) was detected in a family whose affected relatives had additional tumors, including colonic polyposis.

CONCLUSION

We confirm the role of GCM2 germline mutations in the pathogenesis of FIHP, although at a lower rate than in the previous WES study. Further studies are needed to establish the prevalence and the role in the predisposition to FIHP of the novel variants in additional genes.

A Comprehensive PDX Gastric Cancer Collection Captures Cancer Cell-Intrinsic Transcriptional MSI Traits

Gastric cancer is the world's third leading cause of cancer mortality. In spite of significant therapeutic improvements, the clinical outcome for patients with advanced gastric cancer is poor; thus, the identification and validation of novel targets is extremely important from a clinical point of view. We generated a wide, multilevel platform of gastric cancer models, comprising 100 patient-derived xenografts (PDX), primary cell lines, and organoids. Samples were classified according to their histology, microsatellite stability, Epstein-Barr virus status, and molecular profile. This PDX platform is the widest in an academic institution, and it includes all the gastric cancer histologic and molecular types identified by The Cancer Genome Atlas. PDX histopathologic features were consistent with those of patients' primary tumors and were maintained throughout passages in mice. Factors modulating grafting rate were histology, TNM stage, copy number gain of tyrosine kinases/KRAS genes, and microsatellite stability status. PDX and PDX-derived cells/organoids demonstrated potential usefulness to study targeted therapy response. Finally, PDX transcriptomic analysis identified a cancer cell-intrinsic microsatellite instability (MSI) signature, which was efficiently exported to gastric cancer, allowing the identification, among microsatellite stable (MSS) patients, of a subset of MSI-like tumors with common molecular aspects and significant better prognosis. In conclusion, we generated a wide gastric cancer PDX platform, whose exploitation will help identify and validate novel "druggable" targets and optimize therapeutic strategies. Moreover, transcriptomic analysis of gastric cancer PDXs allowed the identification of a cancer cell-intrinsic MSI signature, recognizing a subset of MSS patients with MSI transcriptional traits, endowed with better prognosis. SIGNIFICANCE: This study reports a multilevel platform of gastric cancer PDXs and identifies a MSI gastric signature that could contribute to the advancement of precision medicine in gastric cancer.

Prenatal diagnosis, natural history, postnatal treatment and outcome of 222 cases of spina bifida: experience of a tertiary center

OBJECTIVES

To report on the prenatal ultrasonographic diagnosis of spina bifida (SB) and its natural history, treatment and long-term outcome in a large tertiary referral center.

METHODS

All cases of SB diagnosed between February 1980 and December 2015 in the Obstetric Prenatal Diagnosis Day Unit of the Obstetrics and Gynecology Department at the Catholic University of the Sacred Heart, Rome, were reviewed. All infants with an open defect were delivered by elective Cesarean section and underwent early repair of the spinal defect. A ventriculoperitoneal (VP) shunt and/or third ventriculostomy was performed when needed. Complete postnatal follow-up was carried out by our multidisciplinary team in the majority of cases. The cohort was analyzed in two groups: Group 1 included patients referred between February 1980 and December 1999; Group 2 included patients referred between January 2000 and December 2015.

RESULTS

There was a total of 222 cases of SB with a prenatal diagnosis rate of 94.6% (n = 210), with the majority of defects being meningomyeloceles (n = 142 (64.0%)), affecting the lumbosacral level (n = 110 (49.5%)) and being ≥ 2 cm in size (n = 163/195 (83.6%)). There were 174 (78.4%) live births, with more terminations in Group 2 (26.1%) than in Group 1 (10.8%; P = 0.003). Postnatal surgical repair was conducted in 157 cases (99.4% of eligible cases), with death of an infant who was operated on occurring more often in Group 1 (14.1%) than in Group 2 (4.2%; P = 0.03). VP shunt placement was required in 60.3% of infants operated on after January 2000. Long-term follow-up was available for 136 children (111 with open defects and 25 with closed defects). Infants born since 2000 with an open defect had normal ambulation or a mild defect in 50% of cases and normal or mild deficit of sphincter function in 37.8% of cases. An intelligence quotient of ≥ 70 was observed in the majority of children (81.4%; 35/43 cases). Worse motor function was associated with progressive prenatal ventriculomegaly, level of lesion and VP shunt placement.

CONCLUSIONS

We describe the prenatal diagnosis, natural history and long-term outcome of a large contemporary cohort of SB fetuses and infants. In an era of pioneering fetal surgical techniques for in-utero SB repair, it is important to acknowledge that advances in conventional neonatology and pediatric neurosurgery have allowed increased life expectancy and improved quality of life in patients with SB. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Increased Lactate Secretion by Cancer Cells Sustains Non-cell-autonomous Adaptive Resistance to MET and EGFR Targeted Therapies

The microenvironment influences cancer drug response and sustains resistance to therapies targeting receptor-tyrosine kinases. However, if and how the tumor microenvironment can be altered during treatment, contributing to resistance onset, is not known. We show that, under prolonged treatment with tyrosine kinase inhibitors (TKIs), EGFR- or MET-addicted cancer cells displayed a metabolic shift toward increased glycolysis and lactate production. We identified secreted lactate as the key molecule instructing cancer-associated fibroblasts to produce hepatocyte growth factor (HGF) in a nuclear factor κB-dependent manner. Increased HGF, activating MET-dependent signaling in cancer cells, sustained resistance to TKIs. Functional or pharmacological targeting of molecules involved in the lactate axis abrogated in vivo resistance, demonstrating the crucial role of this metabolite in the adaptive process. This adaptive resistance mechanism was observed in lung cancer patients progressed on EGFR TKIs, demonstrating the clinical relevance of our findings and opening novel scenarios in the challenge to drug resistance.

miR-205 mediates adaptive resistance to MET inhibition via ERRFI1 targeting and raised EGFR signaling

The onset of secondary resistance represents a major limitation to long-term efficacy of target therapies in cancer patients. Thus, the identification of mechanisms mediating secondary resistance is the key to the rational design of therapeutic strategies for resistant patients. MiRNA profiling combined with RNA-Seq in MET-addicted cancer cell lines led us to identify the miR-205/ERRFI1 (ERBB receptor feedback inhibitor-1) axis as a novel mediator of resistance to MET tyrosine kinase inhibitors (TKIs). In cells resistant to MET-TKIs, epigenetically induced miR-205 expression determined the downregulation of ERRFI1 which, in turn, caused EGFR activation, sustaining resistance to MET-TKIs. Anti-miR-205 transduction reverted crizotinib resistance in vivo, while miR-205 over-expression rendered wt cells refractory to TKI treatment. Importantly, in the absence of EGFR genetic alterations, miR-205/ERRFI1-driven EGFR activation rendered MET-TKI-resistant cells sensitive to combined MET/EGFR inhibition. As a proof of concept of the clinical relevance of this new mechanism of adaptive resistance, we report that a patient with a MET-amplified lung adenocarcinoma displayed deregulation of the miR-205/ERRFI1 axis in concomitance with onset of clinical resistance to anti-MET therapy.

Rituximab Treatment Prevents Lymphoma Onset in Gastric Cancer Patient-Derived Xenografts

Patient-Derived Xenografts (PDXs), entailing implantation of cancer specimens in immunocompromised mice, are emerging as a valuable translational model that could help validate biologically relevant targets and assist the clinical development of novel therapeutic strategies for gastric cancer.

More than 30% of PDXs generated from gastric carcinoma samples developed human B-cell lymphomas instead of gastric cancer. These lymphomas were monoclonal, Epstein Barr Virus (EBV) positive, originated tumorigenic cell cultures and displayed a mutational burden and an expression profile distinct from gastric adenocarcinomas. The ability of grafted samples to develop lymphomas did not correlate with patient outcome, nor with the histotype, the lymphocyte infiltration level, or the EBV status of the original gastric tumor, impeding from foreseeing lymphoma onset. Interestingly, lymphoma development was significantly more frequent when primary rather than metastatic samples were grafted.

Notably, the development of such lympho-proliferative disease could be prevented by a short rituximab treatment upon mice implant, without negatively affecting gastric carcinoma engraftment.

Due to the high frequency of human lymphoma onset, our data show that a careful histologic analysis is mandatory when generating gastric cancer PDXs. Such care would avoid misleading results that could occur if testing of putative gastric cancer therapies is performed in lymphoma PDXs. We propose rituximab treatment of mice to prevent lymphoma development in PDX models, averting the loss of human-derived samples.

Downregulating Neuropilin-2 Triggers a Novel Mechanism Enabling EGFR-Dependent Resistance to Oncogene-Targeted Therapies

Neuropilins are a class of cell surface proteins implicated in cell migration and angiogenesis, with aberrant expression in human tumors. Here, we show that the expression of Neuropilin-2 (NRP2) controls EGFR protein levels, thereby impinging on intracellular signaling, viability, and response to targeted therapies of oncogene-addicted cells. Notably, increased NRP2 expression in EGFR-addicted tumor cells led to downregulation of EGFR protein and tumor cell growth inhibition. NRP2 also blunted upregulation of an EGFR "rescue" pathway induced by targeted therapy in Met-addicted carcinoma cells. Cancer cells acquiring resistance to MET oncogene-targeted drugs invariably underwent NRP2 loss, a step required for EGFR upregulation. Mechanistic investigations revealed that NRP2 loss activated NFkB and upregulated the EGFR-associated protein KIAA1199/CEMIP, which is known to oppose the degradation of activated EGFR kinase. Notably, KIAA1199 silencing in oncogene-addicted tumor cells improved therapeutic responses and counteracted acquired drug resistance. Our findings define NRP2 as the pivotal switch of a novel broad-acting and actionable pathway controlling EGFR signaling, and driving resistance to therapies targeting oncogene-addiction.Significance: These important findings identify the cell surface molecule Nrp2 as the pivotal switch of a novel, actionable pathway driving EGFR upregulation and resistance to oncogene- targeted therapies. Cancer Res; 78(4); 1058-68. ©2017 AACR.

Abstract 3851: Targeting HER2 in gastric cancer: Hints from a gastric PDX platform

Introduction: Gastric cancer is the 3rd leading cause of cancer mortality worldwide. Surgery is the only curative treatment strategy and conventional chemotherapy has shown limited efficacy. Trastuzumab (a HER2 mAb), is the only therapy targeting molecular alterations approved so far in gastric cancer, for HER2+ patients with advanced disease. However only a fraction (&lt;20%) of HER2 amplified patients benefits from treatment.

Methods: We have recently generated a molecularly annotated colony of gastro-esophageal PDXs (at the moment, &gt; 70 PDXs). The platform also comprises primary cell lines and 3D-cultured organoids derived from gastric cancer PDXs.

Results and Discussion: At present, we have identified several HER2+ PDXs and generated the corresponding in vitro derivatives. Four HER2+ PDXs, showing 3+ HercepTest score and HER2 amplification &gt; 8 copies (thus theoretically sensitive to Trastuzumab), were selected to undergo ‘xenotrials’ with the following anti-HER2 drugs/combos: Trastuzumab (T); Pertuzumab (P, anti-HER2 mAb); Lapatinib (L, a dual HER2-EGFR tyrosine kinase inhibitor). According to RECIST-like criteria, T induced tumor regression in only 1 out of 4 HER2+ PDXs. Interestingly, in all the tumors but one the combos T+P and T+L were able to bypass resistance to T monotherapy and to induce tumor regression. One tumor was resistant to all the tested therapeutic approaches.

Conclusion: We identified PDXs displaying HER2 gene amplification. Only a minor fraction of them benefited from the anti-HER2 mono-therapy, despite the presence of a strong HER2 gene amplification, while the association of two HER2 inhibiting drugs resulted in intense and prolonged response. This suggests that monotherapy with T might not be the most effective therapeutic approach in gastric cancer patients. We are currently investigating the cause of resistance to anti-HER2 drugs to identify mutations/CNV in tumors showing resistance to Trastuzumab.

Note: This abstract was not presented at the meeting.

Citation Format: Simona Corso, Cristina Migliore, Maria Apicella, Silvia Menegon, Eirini Pectasides, Tania Capeloa, Stefania Durando, Marilisa Cargnelutti, Paola Cassoni, Anna Sapino, Maurizio de Giuli, Adam Bass, Silvia Giordano. Targeting HER2 in gastric cancer: Hints from a gastric PDX platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3851. doi:10.1158/1538-7445.AM2017-3851

Targeted therapies for gastric cancer: failures and hopes from clinical trials

Gastric cancer is the third leading cause of cancer mortality worldwide. As surgery is the only curative treatment strategy and conventional chemotherapy has shown limited efficacy -with a median overall survival of 10 months- new treatments are urgently needed. Trastuzumab and Ramucirumab (targeting HER2 and VEGFR2, respectively) are the only targeted therapies approved so far. Indeed, most Phase III clinical trials evaluating molecular drugs in gastric cancer failed. This review will retrace the relevant clinical trials with molecular therapies performed in gastric cancer patients, discussing the possible reasons for their failure and indicating new perspective for a real improvement of the treatment of this disease.

Abstract A04: Combined anti–MET/EGFR treatment results in complete tumor regression and prevents resistance onset in a MET-amplified gastroesophageal xenopatient cohort

Gastric cancer is the world third leading cause of cancer mortality. In spite of the significant therapeutic advances, the overall clinical outcome for patients with advanced gastric cancer is poor, with 5-20% 5-year survival. The only targeted therapy approved so far are trastuzumab, and Ramucirumab which have given unsatisfactory results. Around 50% of gastric tumors bear genetic alterations affecting tyrosine kinase pathways (mainly EGFR, HER3, FGFR2 and MET pathways, besides HER2) but their clinical validation as tumor drivers is missing. The need for new therapeutic options and the possible presence of “druggable” targets prompted us to investigate potential targeted therapies for this disease.

Our project aims at identifying and validating targeted therapeutic strategies in gastric cancer, through the generation of a platform of gastric tumor patient-derived xenografts (PDXs), animal models in which tumor surgical specimens are directly transferred into mice. Upon engraftment, the tumor is split and re-implanted in a cohort of mice, allowing the simultaneous testing of different drugs on the same tumor. Thanks to the establishment of a network of 15 Italian centers for samples collection, we generated around 80 gastric PDXs and successfully derived cell lines and organoids from engrafted tumors. Among the tumors collected so far, we found HER2, EGFR, FGFR2, MET and KRAS amplifications. This gastric PDX platform will be exploited for: 1) Validation of candidate oncogenes as relevant targets and identification of efficient therapeutic strategies 2) Identification of novel molecular targets; 3) identification of genetic predictors of response/resistance.

In the PDX platform we identified one tumor bearing a high level of MET gene amplification (26 gene copies). We thus performed a preclinical study on a cohort of patient-derived xenografts generated from the MET-amplified gastroesophageal tumor. Despite the high amplification level, MET inhibitors induced only a partial response, while the combined anti-MET/EGFR treatment led to complete tumor regression. Most important, the combo treatment also prevented resistance onset. This data represent the proof of concept that a combined anti-MET/EGFR therapy can be more effective than anti-MET treatment alone in MET-amplified gastroesophageal tumors, in the absence of EGFR genetic lesions.

Citation Format: Simona Corso, Maria Apicella, Silvia Menegon, Marilisa Cargnelutti, Maria Stella Scalzo, Rossella Reddavid, Paola Cassoni, Anna Sapino, Maurizio De Giuli, Silvia Giordano. Combined anti–MET/EGFR treatment results in complete tumor regression and prevents resistance onset in a MET-amplified gastroesophageal xenopatient cohort. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A04.

Abstract 622: Gastric cancer in the age of targeted agents: identification and validation of novel therapeutic strategies through the generation of a patient-derived xenografts platform

Gastric cancer is the world third leading cause of cancer mortality. In spite of the significant therapeutic advances, the overall clinical outcome for patients with advanced gastric cancer is poor, with 5-20% 5-year survival. The only targeted therapy approved so far are trastuzumab, and Ramucirumab which have given unsatisfactory results. Around 50% of gastric tumors bear genetic alterations affecting tyrosine kinase pathways (mainly EGFR, HER3, FGFR2 and MET pathways, besides HER2) but their clinical validation as tumor drivers is missing. The need for new therapeutic options and the possible presence of ‘druggable’ targets prompted us to investigate potential targeted therapies for this disease.

Our project aims at identifying and validating targeted therapeutic strategies in gastric cancer, through the generation of a platform of gastric tumor patient-derived xenografts (PDXs), animal models in which tumor surgical specimens are directly transferred into mice. Upon engraftment, the tumor is split and re-implanted in a cohort of mice, allowing the simultaneous testing of different drugs on the same tumor. Thanks to the establishment of a network of 15 Italian centers for samples collection, we generated around 80 gastric PDXs and successfully derived cell lines and organoids from engrafted tumors. Among the tumors collected so far, we found HER2, EGFR, FGFR2, MET and KRAS amplifications. This gastric PDX platform will be exploited for: 1) Validation of candidate oncogenes as relevant targets and identification of efficient therapeutic strategies 2) Identification of novel molecular targets; 3) identification of genetic predictors of response/resistance.

In the PDX platform we identified one tumor bearing a high level of MET gene amplification (26 gene copies). We thus performed a preclinical study on a cohort of patient-derived xenografts generated from the MET-amplified gastroesophageal tumor. Despite the high amplification level, MET inhibitors induced only a partial response, while the combined anti-MET/EGFR treatment led to complete tumor regression. Most important, the combo treatment also prevented resistance onset. This data represent the proof of concept that a combined anti-MET/EGFR therapy can be more effective than anti-MET treatment alone in MET-amplified gastroesophageal tumors, in the absence of EGFR genetic lesions.

Citation Format: Silvia Menegon, Maria Apicella, Cristina Migliore, Tania Capeloa, Marilisa Cargnelutti, Maurizio Degiuli, Anna Sapino, Paola Cassoni, Michele De Simone, Paolo M. Comoglio, Silvia Marsoni, Simona Corso, Silvia Giordano. Gastric cancer in the age of targeted agents: identification and validation of novel therapeutic strategies through the generation of a patient-derived xenografts platform. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 622.

Abstract B12: Understanding the role of the tumor microenvironment in mediating resistance to anti-MET drugs

Resistance to targeted therapy represents a major challenge to the treatment of cancer patients. Many data support the role of tumor stroma in modulating tumor progression, but little is known about its potential role in drug resistance. This is mostly due to the fact that resistance to targeted therapies has been mainly studied in vitro; thus in vivo tumor models that better mimic human tumors are absolutely needed.

Since MET, the tyrosine kinase receptor for Hepatocyte Growth Factor, is frequently implicated in resistance to kinase-targeted therapies and MET Tyrosine kinase inhibitors (TKIs) are currently in advanced phases of clinical trials, our aim was to investigate a possible role of non-cell-autonomous (microenvironment-mediated) mechanisms of resistance to MET-TKIs.

We generated in vivo models of MET-addicted tumors resistant to anti-MET treatment, subcutaneously injecting the non–small cell lung carcinoma cell line-EBC-1 and the gastric carcinoma cells GTL16 in NOD-SCID mice and treating them with MET inhibitors (JNJ-38877605 or CRIZOTINIB) until resistance onset. In parallel, untreated tumors were used as control.

We analyzed both tumors and cells (tumor cells and murine fibroblasts) isolated and put in culture from WT and resistant (RES) tumors. Through cell viability assays we demonstrated that six out of seven xeno-derived tumor cell lines were not or poorly resistant in vitro to MET inhibitors, suggesting a possible involvement of microenvironment in sustaining resistance.

We reasoned that the stroma of the resistant tumors could be qualitatively and/or quantitatively different from that of the wild-type tumors. To support this idea murine-gene arrays showed a significantly different gene expression profile between WT and resistant murine stroma. Gene-annotation enrichment analysis showed that inflammatory pathways and cancer-associated fibroblast (CAF) genes were particularly up-regulated in resistant versus wt tumors.

In order to understand whether the stroma may confer resistance to MET TKIs, we started to perform in vitro- and in vivo- co-colture experiments. In vitro experiments suggest that tumor cells co-cultured with fibroblasts were less sensitive to the MET inhibitors. We also performed preliminary in vivo experiments to demonstrate that the stroma of resistant tumors can induce resistance. We injected wild-type EBC1 cells (highly sensitive to MET inhibitors), transduced with the luciferase gene, into pre-existing wild-type or resistant tumors. Then we treated mice with the MET inhibitor JNJ-38877605 and monitored the luciferase signal. At the end of the experiment, by IVIS imaging analysis, we observed a decrease of the EBC1 luciferase signal (that is death of the WT labeled injected cells) in WT tumors treated with the MET inhibitor, but an increased luciferase signal in the resistant tumors (meaning that luciferase-labeled WT cells did not die in the presence of the MET inhibitor when in the contest of resistant tumors).

All together our experiments suggest that the microenvironment of resistant tumors can induce resistance to targeted therapies, protecting tumor cells from the effect of the drug.

Citation Format: Simona Corso, Maria Apicella, Silvia Giordano. Understanding the role of the tumor microenvironment in mediating resistance to anti-MET drugs. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B12.

Amplification of the MET receptor drives resistance to anti-EGFR therapies in colorectal cancer

EGF receptor (EGFR)-targeted monoclonal antibodies are effective in a subset of metastatic colorectal cancers. Inevitably, all patients develop resistance, which occurs through emergence of KRAS mutations in approximately 50% of the cases. We show that amplification of the MET proto-oncogene is associated with acquired resistance in tumors that do not develop KRAS mutations during anti-EGFR therapy. Amplification of the MET locus was present in circulating tumor DNA before relapse was clinically evident. Functional studies show that MET activation confers resistance to anti-EGFR therapy both in vitro and in vivo. Notably, in patient-derived colorectal cancer xenografts, MET amplification correlated with resistance to EGFR blockade, which could be overcome by MET kinase inhibitors. These results highlight the role of MET in mediating primary and secondary resistance to anti-EGFR therapies in colorectal cancer and encourage the use of MET inhibitors in patients displaying resistance as a result of MET amplification.

NADPH oxidase activation and assembly during phagocytosis

Generation of superoxide (O2-) by the NADPH-dependent oxidase of polymorphonuclear leukocytes is an essential component of the innate immune response to invading microorganisms. To examine NADPH oxidase function during phagocytosis, we evaluated its activation and assembly following ingestion of serum-opsonized Neisseria meningitidis, serogroup B (NMB), and compared it with that elicited by serum-opsonized zymosan (OPZ). Opsonized N. meningitidis- and OPZ-dependent generation of reactive oxygen species by polymorphonuclear leukocytes peaked early and then terminated. Phosphorylation of p47phox coincided with peak generation of reactive oxygen species by either stimulus, consistent with a role for p47phox phosphorylation during NADPH oxidase activation, and correlated with phagosomal colocalization of flavocytochrome b558 (flavocytochrome b) and p47phox and p67phox (p47/67phox). Termination of respiratory burst activity did not reflect dephosphorylation of plasma membrane- and/or phagosome-associated p47phox; in contrast, the specific activity of phosphorylated p47phox at the phagosomal membrane increased. Most significantly, termination of oxidase activity paralleled the loss of p47/67phox from both NMB and OPZ phagosomes despite the continued presence of flavocytochrome b. These data suggest that 1) the onset of respiratory burst activity during phagocytosis is linked to the phosphorylation of p47phox and its translocation to the phagosome; and 2) termination of oxidase activity correlates with loss of p47/67phox from flavocytochrome b-enriched phagosomes and additional phosphorylation of membrane-associated p47phox.

Neutrophils exposed to bacterial lipopolysaccharide upregulate NADPH oxidase assembly

Bacterial LPS is a pluripotent agonist for PMNs. Although it does not activate the NADPH-dependent oxidase directly, LPS renders PMNs more responsive to other stimuli, a phenomenon known as "priming." Since the mechanism of LPS-dependent priming is incompletely understood, we investigated its effects on assembly and activation of the NADPH oxidase. LPS pretreatment increased superoxide (O2-) generation nearly 10-fold in response to N-formyl methionyl leucyl phenylalanine (fMLP). In a broken-cell O2--generating system, activity was increased in plasma membrane-rich fractions and concomitantly decreased in specific granule-rich fractions from LPS-treated cells. Oxidation-reduction spectroscopy and flow cytometry indicated LPS increased plasma membrane association of flavocytochrome b558. Immunoblots of plasma membrane vesicles from LPS-treated PMNs demonstrated translocation of p47-phox but not of p67-phox or Rac2. However, PMNs treated sequentially with LPS and fMLP showed a three- to sixfold increase (compared with either agent alone) in plasma membrane-associated p47-phox, p67-phox, and Rac2, and translocation paralleled augmented O2- generation by intact PMNs. LPS treatment caused limited phosphorylation of p47-phox, and plasma membrane-enriched fractions from LPS- and/or fMLP-treated cells contained fewer acidic species of p47-phox than did those from cells treated with PMA. Taken together, these studies suggest that redistribution of NADPH oxidase components may underlie LPS priming of the respiratory burst.

Use of pyocin to select a Haemophilus ducreyi variant defective in lipooligosaccharide biosynthesis

Haemophilus ducreyi, a cause of genital ulcer disease in developing countries, appears to facilitate the heterosexual transmission of the human immunodeficiency virus in Africa. Despite an increase in studies of this gram-negative human pathogen, little is known about the pathogenesis of chancroid. Our studies have shown that the lipooligosaccharides (LOS) of H. ducreyi may play an important role in ulcer formation. Monoclonal antibody and mass spectrometric analyses identified a terminal trisaccharide present on H. ducreyi LOS that is immunochemically similar to human paragloboside. This epitope is present on the LOS of Neisseria gonorrhoeae, and it may be the site of attachment for pyocin lysis. We have used pyocin, produced by Pseudomonas aeruginosa, to select LOS variants with sequential saccharide deletions from N. gonorrhoeae. On the basis of the similarities between N. gonorrhoeae and H. ducreyi LOS, we employed the same technique to determine if H. ducreyi strains were susceptible to pyocin lysis. In this study, we report the generation of a pyocin N-resistant H. ducreyi strain which synthesizes a truncated version of the parental LOS. Further studies have shown that this H. ducreyi variant has lost the terminal LOS epitope defined by monoclonal antibody 3F11. This report demonstrates that H. ducreyi is sensitive to pyocins and that this technique can be used to generate H. ducreyi LOS variants. Such variants could be used in comparative studies to relate LOS structure to biologic function in the pathogenesis of chancroid.

Immunity to Haemophilus influenzae type b in young adults: correlation of bactericidal and opsonizing activity of serum with antibody to polyribosylribitol phosphate and lipooligosaccharide before and after vaccination

Naturally acquired humoral immunity is thought to protect adults against serious infections due to Haemophilus influenzae type b (Hib). Antibody to the polyribosylribitol phosphate (PRP) capsule is generally considered protective; antibody to lipooligosaccharide (LOS) or outer membrane protein (OMP) may also play a role. Serum from 23 of 50 healthy young adults had no bactericidal effect (BE) against Hib yet opsonized these organisms for approximately 30% uptake by polymorphonuclear leukocytes. The degree of bactericidal and opsonizing activity in serum from the other 27 subjects generally correlated with the level of antibody to PRP but not to LOS or OMP. However, serum from some individuals had levels of antibody to PRP as high as 4.9 micrograms/ml without BE, and seven of 27 subjects with BE had antibody levels of less than 1 microgram/ml. After vaccination with 20 micrograms of conjugated PRP, the level of antibody to PRP was greater than 5 micrograms/ml in all 50 subjects. BE appeared in 22 of those who originally lacked it, and opsonization increased to approximately 50%.

Antigenic and physical diversity of Neisseria gonorrhoeae lipooligosaccharides

We used mouse monoclonal antibodies (MAbs) to characterize Neisseria gonorrhoeae lipooligosaccharide (LOS). LOSs that bound two or more MAbs in a solid-phase radioimmunoassay usually bound them to different LOS components, as separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE); strains with multiple LOS components on SDS-PAGE usually bound more than one MAb. However, the LOS of some strains bound the same MAb to two LOS components with different relative molecular weights, and some individual LOS components bound more than one MAb. LOSs from different strains bound different amounts of the same MAb at saturation, reflecting differences in the quantitative expression of individual LOS components. Not all components recognized by MAbs were stained by silver after periodate oxidation. Treatment with NaOH variously affected epitopes defined by different MAbs. MAb 3F11 completely inhibited and MAb 2-1-L8 partially inhibited the binding of 125I-labeled 06B4 MAb to WR220 LOS and WR220 outer membranes in competitive binding studies. Other MAbs did not compete with the binding of 125I-labeled 06B4 to either antigen. We conclude that a strain of N. gonorrhoeae elaborates multiple LOSs that can be separated by SDS-PAGE and that are antigenically distinct. Epitope expression within these glycolipids is complex.

Moxalactam epimer disposition in patients undergoing continuous ambulatory peritoneal dialysis

The kinetics of the epimers of moxalactam (R-MOX, S-MOX) were investigated in patients without infections who were receiving continuous ambulatory peritoneal dialysis after both intravenous and intraperitoneal injections of moxalactam. R-MOX and S-MOX were well absorbed from the peritoneal cavity, with mean systemic availability of 0.71 +/- 0.18 and 0.79 +/- 0.18, respectively. After intravenous MOX, serum clearance was 10.2 +/- 3.4 (R-MOX) and 10.9 +/- 3.2 (S-MOX) ml/hr/kg. Net time-averaged peritoneal dialysis clearance of both epimers was minimal, about 10% of serum clearance. Serum and dialysate MOX concentrations were above the minimum inhibitory concentrations for susceptible bacteria for 24 hours after a 2.0 or 1.0 gm intravenous or intraperitoneal dose. Gastrointestinal side effects occurred after a 2.0 gm dose (both intravenous and intraperitoneal) but not after a 1.0 gm dose. There were no significant differences in the kinetics of R-MOX and S-MOX. A single 1.0 gm ip dose leads to serum and dialysate MOX concentrations above the minimum inhibitory concentration for susceptible pathogens for 24 hours.

Purification, characterization, and immunogenicity of cell-associated glucan from Streptococcus mutans

Appropriate immunization with whole cell vaccines of S mutans appear to induce antibodies that inhibit implantation of S mutans on tooth surfaces and associated dental caries. To better understand the mechanisms by which vaccination prevents S mutans implantation and dental caries, and to prepare antigens whose effectiveness and safety can be tested in animal models of caries, we set out to purify and chemically characterize the CAG of S mutans. The CAG of S mutans strain 6715 was prepared by extracting cells with potasssium hydroxide at 100 C. After neutralization and extensive washing, the water-insoluble product was characterized by a battery of chemical analyses and found to be a relatively pure glucan. The CAG was weakly immunogenic in rabbits when administered in Freund's complete adjuvant. In monkeys (M irus) immunized via the parotid duct with an aqueous solution of CAG, a definite but weak serum IgG, IgM, IgA, and salivary IgA antibody response was observed. Absorption experiments showed that the CAG induced antibodies that cross reacted with Sephadex G-25 and others that reacted with unique determinants on CAG. Retention of native antigenic determinants through the purification procedures was verified by the observations that antiserums to CAG reacted with whole cells of S mutans and by the fact that antiserums to S mutans cells reacted with CAG.