RESUMEN
CRLF2 rearrangements, JAK1/2 point mutations, and JAK2 fusion genes have been identified in Philadelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL), a recently described subtype of pediatric high-risk B-precursor ALL (B-ALL) which exhibits a gene expression profile similar to Ph-positive ALL and has a poor prognosis. Hyperactive JAK/STAT and PI3K/mammalian target of rapamycin (mTOR) signaling is common in this high-risk subset. We, therefore, investigated the efficacy of the JAK inhibitor ruxolitinib and the mTOR inhibitor rapamycin in xenograft models of 8 pediatric B-ALL cases with and without CRLF2 and JAK genomic lesions. Ruxolitinib treatment yielded significantly lower peripheral blast counts compared with vehicle (P < .05) in 6 of 8 human leukemia xenografts and lower splenic blast counts (P < .05) in 8 of 8 samples. Enhanced responses to ruxolitinib were observed in samples harboring JAK-activating lesions and higher levels of STAT5 phosphorylation. Rapamycin controlled leukemia burden in all 8 B-ALL samples. Survival analysis of 2 representative B-ALL xenografts demonstrated prolonged survival with rapamycin treatment compared with vehicle (P < .01). These data demonstrate preclinical in vivo efficacy of ruxolitinib and rapamycin in this high-risk B-ALL subtype, for which novel treatments are urgently needed, and highlight the therapeutic potential of targeted kinase inhibition in Ph-like ALL.
Asunto(s)
Antineoplásicos/farmacología , Janus Quinasa 1/antagonistas & inhibidores , Janus Quinasa 2/antagonistas & inhibidores , Leucemia-Linfoma Linfoblástico de Células Precursoras B/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/farmacología , Pirazoles/farmacología , Sirolimus/farmacología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Enfermedad Aguda , Animales , Niño , Modelos Animales de Enfermedad , Evaluación Preclínica de Medicamentos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Inmunoglobulinas/genética , Inmunoglobulinas/metabolismo , Janus Quinasa 1/genética , Janus Quinasa 1/metabolismo , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Ratones , Terapia Molecular Dirigida , Nitrilos , Cromosoma Filadelfia , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras B/mortalidad , Pirimidinas , Receptores de Citocinas/genética , Receptores de Citocinas/metabolismo , Factor de Transcripción STAT5/genética , Factor de Transcripción STAT5/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Tasa de Supervivencia , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Adults and children with high-risk CRLF2-rearranged acute lymphoblastic leukemia (ALL) respond poorly to current cytotoxic chemotherapy and suffer unacceptably high rates of relapse, supporting the need to use alternative therapies. CRLF2 encodes the thymic stromal lymphopoietin (TSLP) receptor, which activates cell signaling in normal lymphocytes on binding its ligand, TSLP. We hypothesized that aberrant cell signaling occurs in CRLF2-rearranged ALL and can be targeted by signal transduction inhibitors of this pathway. In a large number of primary CRLF2-rearranged ALL samples, we observed increased basal levels of pJAK2, pSTAT5, and pS6. We thus characterized the biochemical sequelae of CRLF2 and JAK alterations in CRLF2-rearranged ALL primary patient samples via analysis of TSLP-mediated signal transduction. TSLP stimulation of these leukemias further induced robust JAK/STAT and PI3K/mTOR pathway signaling. JAK inhibition abrogated phosphorylation of JAK/STAT and, surprisingly, of PI3K/mTOR pathway members, suggesting an interconnection between these signaling networks and providing a rationale for testing JAK inhibitors in clinical trials. The PI3K/mTOR pathway inhibitors rapamycin, PI103, and PP242 also inhibited activated signal transduction and translational machinery proteins of the PI3K/mTOR pathway, suggesting that signal transduction inhibitors targeting this pathway also may have therapeutic relevance for patients with CRLF2-rearranged ALL and merit further preclinical testing.