Retinoblastoma (Rb) é o tumor ocular mais frequente na infância e cada grande Centro deve conhecer o perfil dos seus pacientes. Foi realizado um estudo do tipo coorte retrospectivo e incluiu pacientes com Rb atendidos entre 1983 e 2012 nos Serviços de Oncologia Pediátrica, Oftalmologia e Genética Médica do Hospital de Clínicas de Porto Alegre (HCPA). De um total de 165 registros no período foram efetivamente incluídos 140 pacientes, sendo 95,0% destes provenientes de municípios do Rio Grande do Sul. Os sinais mais frequentes ao diagnóstico foram: leucocoria (73,6%) e estrabismo (20,7%). Identificamos a seguinte distribuição: doença unilateral (65,0%), bilateral (32,9%) sendo 80,4% com doença multifocal (p=0,015), trilateral (2,1%). A idade média dos pacientes por ocasião dos primeiros sinais e sintomas foi de 18,1 meses [mediana=12,0] e a idade média ao diagnóstico foi 23,5 meses [mediana=16,5]. Cinquenta pacientes (35,7%) foram diagnosticados no 1º ano de vida. O tempo de diagnóstico médio da coorte foi 5,4 meses [mediana=3,0], (amplitude=0-77,0). A idade média aos primeiros sinais e sintomas do grupo com critérios de hereditariedade foi de 12,3 meses enquanto a do grupo não hereditário foi de 21,6 meses (p=0,001), enquanto a idade média ao diagnóstico foi de 15,9 meses vs. 28 meses, respectivamente (p<0,001). Entretanto não houve diferença na sobrevida entre esses subgrupos. O estadiamento ocular dos pacientes ao diagnóstico na sua maioria foi avançado (classificação de Reese V em 76,5%, Internacional D ou E em 78,1%), sendo que 35,2% dos unilaterais e 34,8% dos bilaterais já apresentavam doença extraocular em pelo menos um olho ao diagnóstico. Quinze pacientes (10,7%) tinham doença metastática ao diagnóstico. Em relação ao tratamento, diferentes modalidades foram utilizadas, sendo a maioria dos pacientes submetidos à cirurgia, sendo esta enucleação em 88,1% e exenteração em 11,9%. Uma parcela significativa dos pacientes foi tratada com quimioterapia sistêmica (57,1%) e/ou radioterapia (37,1%). Do total de pacientes recrutados, 131 (93,6%) permaneceram vinculados ao hospital até 2012 ou até o óbito. Destes, 32 (22,9%) recidivaram, resultando em 19 óbitos com 84,2% por progressão do Rb. Uma segunda neoplasia primária esteve presente em 4,3% (N=6) e dentre esses, um paciente teve uma terceira neoplasia primária. O tempo de seguimento médio foi 323,2 meses [300,3; 346,1]. As sobrevidas nos diferentes subgrupos foram as seguintes: sobrevida global 86,4%; no não metastático 92,0%; no metastático 40,0%; entre os intraoculares 94,0%; entre os extraoculares 68,5%; entre os unilaterais e bilaterais ambos com cerca de 88,0%; entre os trilaterais (N=3) todos foram a óbito; entre os unilaterais intraoculares 94,9% e extraoculares 75,0% e entre os bilaterais intraoculares 94,5% e extraoculares 68,4%. No nosso meio, o diagnóstico de Rb ainda é feito predominantemente em estadios avançados o que reduz a sobrevida dos pacientes e o índice de preservação do olho e da visão, além de aumentar a intensidade dos tratamentos realizados e consequentemente, toxicidade e efeitos tardios destes. Avaliações clínicas e oftalmológicas periódicas nos primeiros anos de vida da criança oferecem maior oportunidade de um diagnóstico precoce e o encaminhamento rápido à um Centro de Referência multidisciplinar que contemple cuidados terciários em Oftalmologia e Oncologia Pediátrica é fundamental. Existe grande necessidade de investimentos regionais que facilitem o acesso ao diagnóstico e tratamento do Rb, o tumor ocular mais frequente na infância. / Retinoblastoma (Rb) is the most frequent ocular tumor diagnosed in children and every pediatric hospital must be familiar with its clinical presentation and patient characteristics. A retrospective cohort study was undertaken, with patients diagnosed with retinoblastoma from 1983 until 2012, treated at the Pediatric Oncology Unit, Ophthalmology Unit, and Medical Genetics Unit of the Hospital de Clínicas de Porto Alegre (HCPA). Of a total of 165 registries during this time frame, 140 patients were included in this study, with 95% of them from the state of Rio Grande do Sul. The most frequent signs and symptoms at diagnosis were: leukocoria (73.6%) and strabismus (20.7%). The following distribution was identified: unilateral disease (65.0%), bilateral disease (32.9%), being 80.4% with multifocal disease, (P=0,015), and trilateral disease (2.1%). The average age of patients at the appearance of the first sign or symptom was 18.1 months [median=12.0] and the average age at diagnosis was 23.5 months [median=16.5]. Fifty patients (35.7%) were diagnosed during their first year of age. The average time to diagnosis was of 5.4 months [median=3.0], (amplitude=0-77.0). In the hereditary retinoblastoma group, the average age at the appearance of the first sign or symptom was 12.3 months, whereas the non-hereditary group presented the first sign or symptom on average at 21.6 months (P=0,001). The average age at diagnosis was 15.9 months vs. 28 months for the hereditary and non-hereditary patients, respectively (P<0.001). However, no significant difference in overall survival was found when both groups were compared. Ocular staging at diagnosis was, for the most part, advanced disease, (Reese V classification: 76.5%, Internacional Classification of Retinoblastoma D or E in 78.1% patients), being that 35.2% of cases were comprised of unilateral disease and 34.8% of patients with bilateral disease already presented with extraocular lesions in at least one eye at diagnosis. Fifteen patients (10.7%) presented with metastasis at diagnosis. With regards to treatment, differnet modalities were employed, being that most patients underwent surgery with enucleation in 88.1% and e exenteration in 11.9%. A significant number of patients received systemic chemotherapy (57.1%) and/or radiotherapy (37.1%). Of all patients included, 131 (93.6%) remained in follow up at the hospital until 2012 or until their demise. Of these patients, 32 (22.9%) relapsed, leading to 19 deaths, 84.2% of them due to disease progression. Secondary malignancies were present in 6 patients (4.3%) and, of these, one patient presented with two different secondary malignancies. The average time of patient follow up was 323.2 months [300.3; 346.1]. Overall survival was of 86.4%, with the following time frames among the different patient subgroups: 92.0% for non-metastatic patients, 40.0% for metastatic patients, intraoculares 94.0% for patients with intraocular disease, and 68.5% for patients with extraocular lesions. With regards to unilateral or bilateral disease, overall survival was of 88.0%; for patients with trilateral disease, (N=3) all patients expired. Survival of patients with unilateral and intraocular disease was of 94.9%; patients with unilateral and extraocular disease presented a overall survival of 75.0%. Patients with bilateral intraocular lesions overall survival was of 94.5%, whereas patients with bilateral and extraocular disease had an overall survival of 68.4%. In our setting, Rb diagnosis still occurs when the patients already manifest advanced disease, which reduces considerably their overall survival and preservation of the ocular globe and vision. Moreover, late diagnosis requires more agressive treatments, and consequently leads to more frequent toxicities and late side effects. Periodic clinical and ophthalmologic evaluations during the first years of a child's life offer a greater chance of early diagnosis and referral to a multidisciplinary pediatric oncology center, which is crucial for the patient’s well being. There is much need of further investments which facilitate patient access to diagnosis and treatment for Rb, which is the most common ocular tumor in children.

Retinoblastoma (Rb) é o tumor ocular mais frequente na infância e cada grande Centro deve conhecer o perfil dos seus pacientes. Foi realizado um estudo do tipo coorte retrospectivo e incluiu pacientes com Rb atendidos entre 1983 e 2012 nos Serviços de Oncologia Pediátrica, Oftalmologia e Genética Médica do Hospital de Clínicas de Porto Alegre (HCPA). De um total de 165 registros no período foram efetivamente incluídos 140 pacientes, sendo 95,0% destes provenientes de municípios do Rio Grande do Sul. Os sinais mais frequentes ao diagnóstico foram: leucocoria (73,6%) e estrabismo (20,7%). Identificamos a seguinte distribuição: doença unilateral (65,0%), bilateral (32,9%) sendo 80,4% com doença multifocal (p=0,015), trilateral (2,1%). A idade média dos pacientes por ocasião dos primeiros sinais e sintomas foi de 18,1 meses [mediana=12,0] e a idade média ao diagnóstico foi 23,5 meses [mediana=16,5]. Cinquenta pacientes (35,7%) foram diagnosticados no 1º ano de vida. O tempo de diagnóstico médio da coorte foi 5,4 meses [mediana=3,0], (amplitude=0-77,0). A idade média aos primeiros sinais e sintomas do grupo com critérios de hereditariedade foi de 12,3 meses enquanto a do grupo não hereditário foi de 21,6 meses (p=0,001), enquanto a idade média ao diagnóstico foi de 15,9 meses vs. 28 meses, respectivamente (p<0,001). Entretanto não houve diferença na sobrevida entre esses subgrupos. O estadiamento ocular dos pacientes ao diagnóstico na sua maioria foi avançado (classificação de Reese V em 76,5%, Internacional D ou E em 78,1%), sendo que 35,2% dos unilaterais e 34,8% dos bilaterais já apresentavam doença extraocular em pelo menos um olho ao diagnóstico. Quinze pacientes (10,7%) tinham doença metastática ao diagnóstico. Em relação ao tratamento, diferentes modalidades foram utilizadas, sendo a maioria dos pacientes submetidos à cirurgia, sendo esta enucleação em 88,1% e exenteração em 11,9%. Uma parcela significativa dos pacientes foi tratada com quimioterapia sistêmica (57,1%) e/ou radioterapia (37,1%). Do total de pacientes recrutados, 131 (93,6%) permaneceram vinculados ao hospital até 2012 ou até o óbito. Destes, 32 (22,9%) recidivaram, resultando em 19 óbitos com 84,2% por progressão do Rb. Uma segunda neoplasia primária esteve presente em 4,3% (N=6) e dentre esses, um paciente teve uma terceira neoplasia primária. O tempo de seguimento médio foi 323,2 meses [300,3; 346,1]. As sobrevidas nos diferentes subgrupos foram as seguintes: sobrevida global 86,4%; no não metastático 92,0%; no metastático 40,0%; entre os intraoculares 94,0%; entre os extraoculares 68,5%; entre os unilaterais e bilaterais ambos com cerca de 88,0%; entre os trilaterais (N=3) todos foram a óbito; entre os unilaterais intraoculares 94,9% e extraoculares 75,0% e entre os bilaterais intraoculares 94,5% e extraoculares 68,4%. No nosso meio, o diagnóstico de Rb ainda é feito predominantemente em estadios avançados o que reduz a sobrevida dos pacientes e o índice de preservação do olho e da visão, além de aumentar a intensidade dos tratamentos realizados e consequentemente, toxicidade e efeitos tardios destes. Avaliações clínicas e oftalmológicas periódicas nos primeiros anos de vida da criança oferecem maior oportunidade de um diagnóstico precoce e o encaminhamento rápido à um Centro de Referência multidisciplinar que contemple cuidados terciários em Oftalmologia e Oncologia Pediátrica é fundamental. Existe grande necessidade de investimentos regionais que facilitem o acesso ao diagnóstico e tratamento do Rb, o tumor ocular mais frequente na infância. / Retinoblastoma (Rb) is the most frequent ocular tumor diagnosed in children and every pediatric hospital must be familiar with its clinical presentation and patient characteristics. A retrospective cohort study was undertaken, with patients diagnosed with retinoblastoma from 1983 until 2012, treated at the Pediatric Oncology Unit, Ophthalmology Unit, and Medical Genetics Unit of the Hospital de Clínicas de Porto Alegre (HCPA). Of a total of 165 registries during this time frame, 140 patients were included in this study, with 95% of them from the state of Rio Grande do Sul. The most frequent signs and symptoms at diagnosis were: leukocoria (73.6%) and strabismus (20.7%). The following distribution was identified: unilateral disease (65.0%), bilateral disease (32.9%), being 80.4% with multifocal disease, (P=0,015), and trilateral disease (2.1%). The average age of patients at the appearance of the first sign or symptom was 18.1 months [median=12.0] and the average age at diagnosis was 23.5 months [median=16.5]. Fifty patients (35.7%) were diagnosed during their first year of age. The average time to diagnosis was of 5.4 months [median=3.0], (amplitude=0-77.0). In the hereditary retinoblastoma group, the average age at the appearance of the first sign or symptom was 12.3 months, whereas the non-hereditary group presented the first sign or symptom on average at 21.6 months (P=0,001). The average age at diagnosis was 15.9 months vs. 28 months for the hereditary and non-hereditary patients, respectively (P<0.001). However, no significant difference in overall survival was found when both groups were compared. Ocular staging at diagnosis was, for the most part, advanced disease, (Reese V classification: 76.5%, Internacional Classification of Retinoblastoma D or E in 78.1% patients), being that 35.2% of cases were comprised of unilateral disease and 34.8% of patients with bilateral disease already presented with extraocular lesions in at least one eye at diagnosis. Fifteen patients (10.7%) presented with metastasis at diagnosis. With regards to treatment, differnet modalities were employed, being that most patients underwent surgery with enucleation in 88.1% and e exenteration in 11.9%. A significant number of patients received systemic chemotherapy (57.1%) and/or radiotherapy (37.1%). Of all patients included, 131 (93.6%) remained in follow up at the hospital until 2012 or until their demise. Of these patients, 32 (22.9%) relapsed, leading to 19 deaths, 84.2% of them due to disease progression. Secondary malignancies were present in 6 patients (4.3%) and, of these, one patient presented with two different secondary malignancies. The average time of patient follow up was 323.2 months [300.3; 346.1]. Overall survival was of 86.4%, with the following time frames among the different patient subgroups: 92.0% for non-metastatic patients, 40.0% for metastatic patients, intraoculares 94.0% for patients with intraocular disease, and 68.5% for patients with extraocular lesions. With regards to unilateral or bilateral disease, overall survival was of 88.0%; for patients with trilateral disease, (N=3) all patients expired. Survival of patients with unilateral and intraocular disease was of 94.9%; patients with unilateral and extraocular disease presented a overall survival of 75.0%. Patients with bilateral intraocular lesions overall survival was of 94.5%, whereas patients with bilateral and extraocular disease had an overall survival of 68.4%. In our setting, Rb diagnosis still occurs when the patients already manifest advanced disease, which reduces considerably their overall survival and preservation of the ocular globe and vision. Moreover, late diagnosis requires more agressive treatments, and consequently leads to more frequent toxicities and late side effects. Periodic clinical and ophthalmologic evaluations during the first years of a child's life offer a greater chance of early diagnosis and referral to a multidisciplinary pediatric oncology center, which is crucial for the patient’s well being. There is much need of further investments which facilitate patient access to diagnosis and treatment for Rb, which is the most common ocular tumor in children.

Retinoblastoma (Rb) é o tumor ocular mais frequente na infância e cada grande Centro deve conhecer o perfil dos seus pacientes. Foi realizado um estudo do tipo coorte retrospectivo e incluiu pacientes com Rb atendidos entre 1983 e 2012 nos Serviços de Oncologia Pediátrica, Oftalmologia e Genética Médica do Hospital de Clínicas de Porto Alegre (HCPA). De um total de 165 registros no período foram efetivamente incluídos 140 pacientes, sendo 95,0% destes provenientes de municípios do Rio Grande do Sul. Os sinais mais frequentes ao diagnóstico foram: leucocoria (73,6%) e estrabismo (20,7%). Identificamos a seguinte distribuição: doença unilateral (65,0%), bilateral (32,9%) sendo 80,4% com doença multifocal (p=0,015), trilateral (2,1%). A idade média dos pacientes por ocasião dos primeiros sinais e sintomas foi de 18,1 meses [mediana=12,0] e a idade média ao diagnóstico foi 23,5 meses [mediana=16,5]. Cinquenta pacientes (35,7%) foram diagnosticados no 1º ano de vida. O tempo de diagnóstico médio da coorte foi 5,4 meses [mediana=3,0], (amplitude=0-77,0). A idade média aos primeiros sinais e sintomas do grupo com critérios de hereditariedade foi de 12,3 meses enquanto a do grupo não hereditário foi de 21,6 meses (p=0,001), enquanto a idade média ao diagnóstico foi de 15,9 meses vs. 28 meses, respectivamente (p<0,001). Entretanto não houve diferença na sobrevida entre esses subgrupos. O estadiamento ocular dos pacientes ao diagnóstico na sua maioria foi avançado (classificação de Reese V em 76,5%, Internacional D ou E em 78,1%), sendo que 35,2% dos unilaterais e 34,8% dos bilaterais já apresentavam doença extraocular em pelo menos um olho ao diagnóstico. Quinze pacientes (10,7%) tinham doença metastática ao diagnóstico. Em relação ao tratamento, diferentes modalidades foram utilizadas, sendo a maioria dos pacientes submetidos à cirurgia, sendo esta enucleação em 88,1% e exenteração em 11,9%. Uma parcela significativa dos pacientes foi tratada com quimioterapia sistêmica (57,1%) e/ou radioterapia (37,1%). Do total de pacientes recrutados, 131 (93,6%) permaneceram vinculados ao hospital até 2012 ou até o óbito. Destes, 32 (22,9%) recidivaram, resultando em 19 óbitos com 84,2% por progressão do Rb. Uma segunda neoplasia primária esteve presente em 4,3% (N=6) e dentre esses, um paciente teve uma terceira neoplasia primária. O tempo de seguimento médio foi 323,2 meses [300,3; 346,1]. As sobrevidas nos diferentes subgrupos foram as seguintes: sobrevida global 86,4%; no não metastático 92,0%; no metastático 40,0%; entre os intraoculares 94,0%; entre os extraoculares 68,5%; entre os unilaterais e bilaterais ambos com cerca de 88,0%; entre os trilaterais (N=3) todos foram a óbito; entre os unilaterais intraoculares 94,9% e extraoculares 75,0% e entre os bilaterais intraoculares 94,5% e extraoculares 68,4%. No nosso meio, o diagnóstico de Rb ainda é feito predominantemente em estadios avançados o que reduz a sobrevida dos pacientes e o índice de preservação do olho e da visão, além de aumentar a intensidade dos tratamentos realizados e consequentemente, toxicidade e efeitos tardios destes. Avaliações clínicas e oftalmológicas periódicas nos primeiros anos de vida da criança oferecem maior oportunidade de um diagnóstico precoce e o encaminhamento rápido à um Centro de Referência multidisciplinar que contemple cuidados terciários em Oftalmologia e Oncologia Pediátrica é fundamental. Existe grande necessidade de investimentos regionais que facilitem o acesso ao diagnóstico e tratamento do Rb, o tumor ocular mais frequente na infância. / Retinoblastoma (Rb) is the most frequent ocular tumor diagnosed in children and every pediatric hospital must be familiar with its clinical presentation and patient characteristics. A retrospective cohort study was undertaken, with patients diagnosed with retinoblastoma from 1983 until 2012, treated at the Pediatric Oncology Unit, Ophthalmology Unit, and Medical Genetics Unit of the Hospital de Clínicas de Porto Alegre (HCPA). Of a total of 165 registries during this time frame, 140 patients were included in this study, with 95% of them from the state of Rio Grande do Sul. The most frequent signs and symptoms at diagnosis were: leukocoria (73.6%) and strabismus (20.7%). The following distribution was identified: unilateral disease (65.0%), bilateral disease (32.9%), being 80.4% with multifocal disease, (P=0,015), and trilateral disease (2.1%). The average age of patients at the appearance of the first sign or symptom was 18.1 months [median=12.0] and the average age at diagnosis was 23.5 months [median=16.5]. Fifty patients (35.7%) were diagnosed during their first year of age. The average time to diagnosis was of 5.4 months [median=3.0], (amplitude=0-77.0). In the hereditary retinoblastoma group, the average age at the appearance of the first sign or symptom was 12.3 months, whereas the non-hereditary group presented the first sign or symptom on average at 21.6 months (P=0,001). The average age at diagnosis was 15.9 months vs. 28 months for the hereditary and non-hereditary patients, respectively (P<0.001). However, no significant difference in overall survival was found when both groups were compared. Ocular staging at diagnosis was, for the most part, advanced disease, (Reese V classification: 76.5%, Internacional Classification of Retinoblastoma D or E in 78.1% patients), being that 35.2% of cases were comprised of unilateral disease and 34.8% of patients with bilateral disease already presented with extraocular lesions in at least one eye at diagnosis. Fifteen patients (10.7%) presented with metastasis at diagnosis. With regards to treatment, differnet modalities were employed, being that most patients underwent surgery with enucleation in 88.1% and e exenteration in 11.9%. A significant number of patients received systemic chemotherapy (57.1%) and/or radiotherapy (37.1%). Of all patients included, 131 (93.6%) remained in follow up at the hospital until 2012 or until their demise. Of these patients, 32 (22.9%) relapsed, leading to 19 deaths, 84.2% of them due to disease progression. Secondary malignancies were present in 6 patients (4.3%) and, of these, one patient presented with two different secondary malignancies. The average time of patient follow up was 323.2 months [300.3; 346.1]. Overall survival was of 86.4%, with the following time frames among the different patient subgroups: 92.0% for non-metastatic patients, 40.0% for metastatic patients, intraoculares 94.0% for patients with intraocular disease, and 68.5% for patients with extraocular lesions. With regards to unilateral or bilateral disease, overall survival was of 88.0%; for patients with trilateral disease, (N=3) all patients expired. Survival of patients with unilateral and intraocular disease was of 94.9%; patients with unilateral and extraocular disease presented a overall survival of 75.0%. Patients with bilateral intraocular lesions overall survival was of 94.5%, whereas patients with bilateral and extraocular disease had an overall survival of 68.4%. In our setting, Rb diagnosis still occurs when the patients already manifest advanced disease, which reduces considerably their overall survival and preservation of the ocular globe and vision. Moreover, late diagnosis requires more agressive treatments, and consequently leads to more frequent toxicities and late side effects. Periodic clinical and ophthalmologic evaluations during the first years of a child's life offer a greater chance of early diagnosis and referral to a multidisciplinary pediatric oncology center, which is crucial for the patient’s well being. There is much need of further investments which facilitate patient access to diagnosis and treatment for Rb, which is the most common ocular tumor in children.

Adulte ou pédiatrique, les tumeurs solides ont besoin d’oxygène et de nutriments pour se développer et métastaser. Leur apport est assuré par la néo-vascularisation tumorale issue d’un processus multifactoriel appelé l’angiogénèse. Son équilibre est maintenu par une balance entre facteurs pro- et anti-angiogéniques. Elle fait partie des principales cibles pour traiter les cancers et l’inhibition de la voie VEGF en est un facteur clé. Cependant, la réponse aux agents anti-angiogéniques a montré, malgré des résultats encourageants, un effet transitoire associé à l’apparition d’une résistance adaptative de la tumeur.Nous avons étudié l’inhibition de l’angiogénèse et les mécanismes potentiels d’échappement dans les tumeurs pédiatriques solides, et principalement dans le neuroblastome. Le neuroblastome est une tumeur originaire de la crête neurale et atteint généralement l’enfant jeune. Nous avons exploré l’effet anti-tumoral de l’inhibition sélective des récepteurs 1, 2, 3 du VEGF à l’aide de l’inhibiteur à tyrosine kinase axitinib dans divers modèles précliniques de neuroblastome. L’axitinib a montré une activité anti-tumorale modérée associée à une inhibition de la vascularisation. Néanmoins, après un traitement prolongé in vitro, les cellules tumorales IGR-N91-Luc deviennent résistantes à l’axitinib. Elles prolifèrent normalement mais secrètent de «l’ hepatocyte growth factor» (HGF) et activent la voie MAPK. In vivo, le traitement prolongé par axitinib entraîne le développement d’un phénotype plus agressif de la tumeur avec l’augmentation du nombre d’animaux présentant des métastases, associée à une activation de la voie SRC. Ceci nous a conduit à explorer l’effet d’une inhibition ciblant principalement VEGFR2 et MET (récepteur à l’HGF) avec le cabozantinib. Ainsi nous avons contrôlé le développement tumoral en inhibant la néo-vascularisation et l’activation de SRC, et induit la mort cellulaire dans le modèle orthotopique IGR-N91-Luc et inhibé le développement métastatique dans le modèle systémique IMR-32-Luc. Par ailleurs, nous avons étendu notre exploration à d’autres facteurs jouant un rôle dans l’angiogénèse comme FGFR ou PDGFR car ils représentent, comme MET, de puissants oncogènes. Pour cibler simultanément VEGFR et PDGFR, nous avons utilisé l’inhibiteur multi-kinase regorafenib. In vivo, à des doses bien tolérées qui permettent un traitement prolongé, le regorafenib a montré une activité anti-tumorale significative. Cet effet a été associé principalement à une forte inhibition de la vascularisation mais également à l’induction de la mort cellulaire. En élargissant notre étude à d’autres modèles de tumeurs pédiatriques, nous avons observé que son activité est indépendante du type histologique. Compte tenu du caractère oncogénique de PDGFR, nous avons évalué cet inhibiteur dans des modèles présentant une amplification du gène PDGFRA, qui entraine une surexpression et une activation forte du récepteur. Combiné avec des thérapies standards capables d’induire des dommages à l’ADN telles que l’irradiation ou l’irinotecan, l’effet du regorafenib a été potentialisé, notamment dans les modèles amplifiés pour le gène PDGFRA se traduisant par des régressions tumorales. Ces évaluations précliniques soutiennent le développement d’une nouvelle stratégie thérapeutique pour les enfants atteints de tumeurs solides. / Solid tumors either adult or pediatric need oxygen and nutrients to grow and metastasize. Their input is provided by tumor neovascularization after a multifactorial process called angiogenesis. Balance is maintained by equilibrium between pro and anti-angiogenic factors. It is one of the main targets for treating cancers and the inhibition of the VEGF pathway is a key factor. However, despite encouraging results, the response to anti-angiogenic agents showed a transient effect associated with the development of an adaptive tumor resistance. We studied the inhibition of angiogenesis and potential escape mechanisms in solid pediatric tumors, mainly in neuroblastoma. Neuroblastoma is a solid tumor derived from the neural crest and it usually affects childhood. We investigated the anti-tumor effect of selective inhibition of VEGF receptors 1, 2, 3 using the tyrosine kinase inhibitor axitinib in various preclinical neuroblastoma l models. Axitinib showed a moderate anti-tumor activity associated with the inhibition of vascularization. However, after prolonged treatment in vitro, tumor cells IGR-N91-Luc become resistant to axitinib. They proliferate normally but secrete the "hepatocyte growth factor" (HGF) and activate the MAPK pathway. In vivo, prolonged treatment by axitinib results in the development of a more aggressive tumor phenotype with an increase in the number of animals exhibiting metastases associated with an activation of SRC signaling. This led us to explore the effect of inhibiting concomitant VEGFR2 and MET (HGF receptor), main cabozantinib targets. So we stabilized tumor growth by inhibiting the neovascularization and activation of SRC, induced cell death in the orthotopic model IGR-N91-Luc and inhibited metastatic development in the IMR-32-Luc systemic model. In addition, we extended our exploration of other factors that play a role in angiogenesis like FGFR or PDGFR because they represent, like MET, powerful oncogenes. To simultaneously target VEGFR and PDGFR, we used the multi-kinase inhibitor regorafenib. In vivo, at well-tolerated doses that allow prolonged treatment, regorafenib showed significant anti-tumor activity. This effect was mainly associated with a strong inhibition of vascularization, but also (with) induction of cell death. By expanding our study to other models of pediatric tumors, we observed that its activity was independent of histologic type. Given the oncogenic character of PDGFR, we evaluated the inhibitor in models which present a PDGFRA gene amplification, which results in a strong activation of the receptor. Combined with standard therapies that can induce DNA damages such as irinotecan or radiation, the effect of regorafenib was potentiated, mainly in PDGFRA gene amplified models, where tumor regressions were obtained. These preclinical evaluations support the development of a new therapeutic strategy for children with solid tumors.

Une des plus grandes avancées en cancérologie et en génétique au cours des vingt dernières années fût l'identification des formes héréditaires de cancer et des gènes deprédisposition impliqués. Chez une majorité de patients soupçonnés de présenter une formehéréditaire de cancer, les analyses centrées sur les gènes connus pour être impliqués dansles prédispositions mendéliennes au cancer restent bien souvent négatives. Aujourd'hui,grâce à l'émergence du séquençage à haut-débit (NGS), il est possible de séquencerl'ensemble des exons (exome) d'un individu ou plusieurs centaines de gènes dans un lapsde temps court et à des coûts raisonnables. Dans ce contexte, nous avons appliqué plusieurs stratégies basées sur ces nouveaux outils, avec l'objectif d'identifier de nouvellesbases moléculaires des cancers héréditaires à survenue précoce. Tout d’abord, nous avons employé une stratégie d'analyse exomique intrafamiliale dans une famille atypique présentant des chondrosarcomes de localisation thoracique pour lesquels aucune base moléculaire n'avait pu être mise en évidence. Grâce à cette stratégie, nous avons pu identifier une altération tronquante du gène EXT2 (NM_000401.3; c.237G>A; p.Trp79*). Les altérations perte de fonction documentées pour ce gène sont impliquées dans la maladie des ostéochondromes multiples (OM), des tumeurs bénignes. Or, dans cette famille, aucun signe clinique d'OM n'était présent. Ces travaux nous ont donc permis d'étendre le spectre phénotypique des mutations EXT2 et de modifier la prise en charge clinique de cette famille. Nous avons ensuite employé une stratégie d'analyse exomique soustractive de trio enfant malade / parents sains dans le but d’identifier des mutations de novo potentiellement responsables de la prédisposition génétique au cancer observée chez un jeune patient ayant développé un médulloblastome du cervelet à l’âge de 8 ans, suivi d’un méningiome à 22 ans. L’analyse exomique du trio a révélé l’existence chez ce patient d'une mutation de novo faux-sens affectant un acide aminé très conservé de la protéine HID-1. Cette dernière est particulièrement exprimée dans les cellules neuronales et sécrétrices, et semble fonctionner autour de l’appareil de Golgi pour réguler le tri des vésiculesnouvellement formées. Ainsi, notre hypothèse est qu’un défaut de la protéine HID-1, lié à une mutation du gène HID-1, perturberait la voie de sécrétion et participerait à la genèse du médulloblastome. Ces travaux, toujours en cours, démontrent à la fois la force de la stratégie exomique de trio pour identifier rapidement des mutations de novo et illustre toute la difficultéd'interprétation des variants détectés dans des gènes non impliqués dans le cancer. Par ailleurs, nous avons appliqué une stratégie exomique soustractive et interfamiliale à une cohorte de dix patients ayant développé un corticosurrénalome à un âge très précoce et pour lesquels aucune base moléculaire n'a pu être mise en évidence. Malheureusement, nous n'avons pas pu identifier de nouvelles bases moléculaires du corticosurrénalome de l'enfant par ces techniques. Enfin, sous l'hypothèse que des mutations rares ou privées dans un nombre limité de gènes impliqués dans le cancer contribueraient à des formes héréditaires de cancer, nous avons entrepris un projet visant à séquencer à haut débit 201 gènes fortement impliqués dans le cancer chez des patients ayant développé des tumeurs à un âge pédiatrique. Les premiers résultats de ce projet toujours en cours ont permis de confirmer la robustesse de cette technique et suggèrent une extension phénotypique du spectre des mutations DICER1 ainsi qu'une contribution oligogénique des gènes de réparation de l'ADN dans les tumeurs pédiatriques. L'ensemble de ces résultats seront bientôt compilés au sein d'une base de données et bénéficieront d'une analyse statistique fine avec l'objectif d'identifier des enrichissements en variants rares dans des gènes ou voies biologiques. / One of the greatest advances in oncology and genetics over the past 20 years has been the identification of hereditary forms of cancer and of the cancer genes. Nevertheless, in a majority of patients suspected to present an inherited form of cancer, analyses of the genes known to be involved in the Mendelian predispositions to cancer often remain negative. Today, thanks to the emergence of high-throughput sequencing (NGS), it is now possible to sequence all exons of an individual (exome) or several hundred genes in a short period of time and for a reasonable cost. In this context, we have applied several strategiesbased on these new tools in order to identify new molecular basis of early-onset cancers. First, we applied an intra-familial exome analysis strategy to an atypical family with chondrosarcomas of the chest, for which no molecular basis could be identified. Using this strategy, we were able to identify a truncating alteration of the EXT2 gene NM_000401.3; c.237G> A; p.Trp79 *). The documented loss of function alterations of this gene are implicated in a disease called multiple osteochondromas (OM), associated with benign lesions. Interestingly, these patients showed no clinical signs of OM indicating a potential phenotypic extension of EXT2 mutations. Plus, this work allowed us to change the clinical management of this family. We then used a strategy of subtractive exomic analysis of trio sick child/healthy parents in order to identify de novo mutations in a young patient who developed a medulloblastoma of the cerebellum at 8 years-old followed by a meningioma at 22 years-old. The analysis of the trio revealed the existence of a de novo mutation affecting a highly conserved amino acid of the HID-1 protein. HID-1 is specifically expressed in neuronal and secretory cells, and seems to function around the Golgi apparatus to regulate the sorting of newly formed vesicles. Our hypothesis is that a defect of the HID-1 protein linked to a mutation of the HID-1 gene, could alter the secretory pathway therefore contributing to the development of the tumor. This work, which is still ongoing, demonstrates both the strength of the trio strategy for the rapid identification of de novo mutations and illustrates all the difficulty of interpreting variants detected in genes not yet involved in cancer. Then, thanks to the recruitment of the Laboratory of Molecular Genetics of the CHU of Rouen, we have collected a cohort of 10 patients who developed an adrenocortical carcinoma (ACC) at a very early age and for which no molecular basis could be identified. Despite subtractive and inter-familial exomic analyses, we were unable to highlight new molecular bases for these cases of pediatric ACC. Finally, under the assumption that rare or private mutations in a limited number of genes involved in cancer could contribute to inherited forms of cancer, we undertook a project to sequence 201 genes involved in cancer in patients who developed tumors at a pediatric age. The first results of this project confirmed the robustness of this technique and suggested a phenotypic extension of the DICER1 mutation spectrum as well as an oligogenic contribution of DNA repair genes in pediatric tumors. Soon, these results will be compiled in a database and will benefit from a statistical analysis with the objective to identify enrichment of rare variants in specific genes or biological pathways in these patients compared to control individuals.