Amy Smith

Targetable Kinase-Activating Lesions in Ph-like Acute Lymphoblastic Leukemia

BACKGROUND Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is characterized by a gene-expression profile similar to that of BCR-ABL1-positive ALL, alterations of lymphoid transcription factor genes, and a poor outcome. The frequency and spectrum of genetic alterations in Ph-like ALL and its responsiveness to tyrosine kinase inhibition are undefined, especially in adolescents and adults. METHODS We performed genomic profiling of 1725 patients with precursor B-cell ALL and detailed genomic analysis of 154 patients with Ph-like ALL. We examined the functional effects of fusion proteins and the efficacy of tyrosine kinase inhibitors in mouse pre-B cells and xenografts of human Ph-like ALL. RESULTS Ph-like ALL increased in frequency from 10% among children with standard-risk ALL to 27% among young adults with ALL and was associated with a poor outcome. Kinase-activating alterations were identified in 91% of patients with Ph-like ALL; rearrangements involving ABL1, ABL2, CRLF2, CSF1R, EPOR, JAK2, NTRK3, PDGFRB, PTK2B, TSLP, or TYK2 and sequence mutations involving FLT3, IL7R, or SH2B3 were most common. Expression of ABL1, ABL2, CSF1R, JAK2, and PDGFRB fusions resulted in cytokine-independent proliferation and activation of phosphorylated STAT5. Cell lines and human leukemic cells expressing ABL1, ABL2, CSF1R, and PDGFRB fusions were sensitive in vitro to dasatinib, EPOR and JAK2 rearrangements were sensitive to ruxolitinib, and the ETV6-NTRK3 fusion was sensitive to crizotinib. CONCLUSIONS Ph-like ALL was found to be characterized by a range of genomic alterations that activate a limited number of signaling pathways, all of which may be amenable to inhibition with approved tyrosine kinase inhibitors. Trials identifying Ph-like ALL are needed to assess whether adding tyrosine kinase inhibitors to current therapy will improve the survival of patients with this type of leukemia. (Funded by the American Lebanese Syrian Associated Charities and others.).

Chondroitin Sulfate Proteoglycans Potently Inhibit Invasion and Serve as a Central Organizer of the Brain Tumor Microenvironment

Glioblastoma (GBM) remains the most pervasive and lethal of all brain malignancies. One factor that contributes to this poor prognosis is the highly invasive character of the tumor. GBM is characterized by microscopic infiltration of tumor cells throughout the brain, whereas non-neural metastases, as well as select lower grade gliomas, develop as self-contained and clearly delineated lesions. Illustrated by rodent xenograft tumor models as well as pathological human patient specimens, we present evidence that one fundamental switch between these two distinct pathologies–invasion and noninvasion–is mediated through the tumor extracellular matrix. Specifically, noninvasive lesions are associated with a rich matrix containing substantial amounts of glycosylated chondroitin sulfate proteoglycans (CSPGs), whereas glycosylated CSPGs are essentially absent from diffusely infiltrating tumors. CSPGs, acting as central organizers of the tumor microenvironment, dramatically influence resident reactive astrocytes, inducing their exodus from the tumor mass and the resultant encapsulation of noninvasive lesions. Additionally, CSPGs induce activation of tumor-associated microglia. We demonstrate that the astrogliotic capsule can directly inhibit tumor invasion, and its absence from GBM presents an environment favorable to diffuse infiltration. We also identify the leukocyte common antigen-related phosphatase receptor (PTPRF) as a putative intermediary between extracellular glycosylated CSPGs and noninvasive tumor cells. In all, we present CSPGs as critical regulators of brain tumor histopathology and help to clarify the role of the tumor microenvironment in brain tumor invasion.

Phase I and Pharmacokinetic Study of Cetuximab and Irinotecan in Children With Refractory Solid Tumors: A Study of the Pediatric Oncology Experimental Therapeutic Investigators' Consortium

PURPOSE To determine the dose of cetuximab that can be safely combined with irinotecan for treatment of pediatric and adolescent patients with refractory solid tumors. PATIENTS AND METHODS This open-label, phase I study enrolled patients ages 1 to 18 years with advanced refractory solid tumors, including tumors of the CNS. Patient cohorts by age group (children, ages 1 to 12 years; adolescents, ages 13 to 18 years) received escalating weekly doses of cetuximab (75, 150, 250 mg/m(2)) in a 3 + 3 design, plus irinotecan (16 or 20 mg/m(2)/d) for 5 days for 2 consecutive weeks every 21 days. The primary end points were establishing the maximum-tolerated dose (MTD), recommended phase II dose (RPIID), and pharmacokinetics of the combination. Preliminary safety and efficacy data were also collected. RESULTS Twenty-seven children and 19 adolescents received a median of 7.1 and 6.0 weeks of cetuximab therapy, respectively. Cetuximab 250 mg/m(2) weekly plus irinotecan 16 mg/m(2)/d (pediatric) or 20 mg/m(2)/d (adolescent) have been established as the MTD/RPIID. Dose-limiting toxicities included diarrhea and neutropenia. Mild to moderate (grade 1 to 2) acneiform rash occurred in a majority of patients; no grade 3 to 4 rashes were observed. Cetuximab demonstrated dose-dependent clearance in both children and adolescents, similar to that in adults. There were two confirmed partial responses, both in patients with CNS tumors. Stable disease was achieved in 18 patients overall, including 10 patients with CNS tumors (38.5%). CONCLUSION The cetuximab/irinotecan combination can be given safely to children and adolescents with cancer. Promising activity, particularly in CNS tumors, warrants phase II evaluation of this regimen.

Intracranial Germ Cell Tumors: A Single Institution Experience and Review of the Literature

There is little literature to guide therapy in children and young adults with intracranial germ cell tumors. We present 17 consecutively diagnosed intracranial germ cell tumors at The Childrens Hospital, Denver, from 1995 to 2001. Of 17 patients, 3 had considerable delay in diagnosis. Two with suprasellar tumors presented with dementia, blindness and pan-hypopituitarism and another with recurrent subarachnoid hemorrhage. Seven had germinoma, three were metastatic at diagnosis. Ten had non-germinomatous germ cell tumors (NGGCT), 5/10 were alpha feto-protein (AFP) positive only, one β-human chorionic growth (βHCG) factor positive only, 3 positive for AFP and βHCG, and 1 malignant teratoma. Therapy for metastatic patients consisted of chemotherapy followed by craniospinal radiation (CSI). Patients with localized disease received chemotherapy followed by focal radiation. Two patients received chemotherapy only, one because she died of sepsis while receiving chemotherapy and one because of neurologic injury incurred during surgery parents elected for no therapy. Three patients have died, one of tumor recurrence, one from a remote complication of surgery and one of sepsis. Twelve patients are alive without evidence of disease from 10 to 68 months (median 31.5 months). All five children with only AFP positivity, treated with chemotherapy and focal radiation are alive without evidence of disease at 10, 16, 22, 41 and 41 months. Thus, there is little evidence that CSI is necessary in non-metastatic germinomas and AFP positive NGGCTs when combined chemotherapy and radiation therapy is used. However, complications of delayed diagnosis, surgery and chemotherapy are important causes of mortality, with only one patient dying of tumor.

Second tumors in pediatric patients treated with radiotherapy to the central nervous system.

ObjectiveTo determine the rate of second tumors in pediatric patients treated with radiotherapy to the central nervous system (CNS) with long-term follow-up. MethodsWe retrospectively reviewed the charts of 370 consecutive pediatric patients with solid tumors and leukemia treated at the University of Florida from 1963 to 2006 with curative CNS radiotherapy. The median age was 8.1 years (range, 0.2 to 19.0 y). One hundred seventy-two (47%), 79 (21%), and 119 (32%) patients received focal, whole-brain, and craniospinal irradiation, respectively. Variables analyzed for prognostic value included primary tumor histology, patient age at primary treatment, volume of tissue irradiated, dose to the tumor bed, treatment with chemotherapy, and location of the primary tumor. ResultsEighteen second tumors were diagnosed in 16 patients. The actuarial incidences of second tumors were 3%, 8%, and 24% at 10, 20, and 30 years of follow-up, respectively. On univariate analysis, no single variable was found to be predictive of second tumor incidence. The most common second tumor after radiation for a primary solid CNS tumor was meningioma (63%), for which successful salvage was common (89%). Second gliomas were most common among patients treated for leukemia and were uniformly fatal. The most common cause of death among 5-year survivors was late relapse of their primary tumor. ConclusionsThe risk of second tumors after CNS radiation is significant and does not plateau with long-term follow-up. Most second tumors after radiotherapy for solid CNS tumors are meningiomas that can be successfully salvaged.

Clinical, Pathological, and Molecular Characterization of Infant Medulloblastomas Treated with Sequential High‐Dose Chemotherapy

High‐dose chemotherapy (HDC) strategies were developed to avoid unacceptable neurotoxicity associated with craniospinal irradiation in infants with embryonal brain tumors. However, the impact of molecular and pathological characterizations in such approaches and long‐term outcome have not been widely described in young children.

Temozolomide and oral VP-16 for children and young adults with recurrent or treatment-induced malignant gliomas

Children and young adults with recurrent or treatment‐induced malignant gliomas have limited responses to temozolomide or oral VP‐16 when either is administered as a single agent. We postulated that a combination of these two drugs for patients with recurrent or treatment‐induced malignant gliomas might result in better and more prolonged responses. A retrospective analysis was performed on patients treated with the combination of temozolomide and VP‐16.

Phase 2 study of safety and efficacy of nimotuzumab in pediatric patients with progressive diffuse intrinsic pontine glioma

BACKGROUND The prognosis of diffuse intrinsic pontine glioma (DIPG) remains poor, with no drug proven to be effective. METHODS Patients with clinically and radiologically confirmed, centrally reviewed DIPG, who had failed standard first-line therapy were eligible for this multicenter phase II trial. The anti-epidermal growth factor receptor (EGFR) antibody, nimotuzumab (150 mg/m(2)), was administered intravenously once weekly from weeks 1 to 7 and once every 2 weeks from weeks 8 to 18. Response evaluation was based on clinical and MRI assessments. Patients with partial response (PR) or stable disease (SD) were allowed to continue nimotuzumab. RESULTS Forty-four patients received at least one dose of nimotuzumab (male/female, 20/24; median age, 6.0 years; range, 3.0-17.0 years). All had received prior radiotherapy. Treatment was well tolerated. Eighteen children experienced serious adverse events (SAEs). The majority of SAEs were associated with disease progression. Nineteen patients completed 8 weeks (W8) of treatment: There were 2 PRs, 6 SDs, and 11 progressions. Five patients completed 18 weeks (W18) of treatment: 1 of 2 patients with PR at W8 remained in PR at W18, and 3 of 6 children with SD at W8 maintained SD at W18. Time to progression following initiation of nimotuzumab for the 4 patients with SD or better at W18 was 119, 157, 182 and 335 days, respectively. Median survival time was 3.2 months. Two patients lived 663 and 481 days from the start of nimotuzumab. CONCLUSIONS Modest activity of nimotuzumab in DIPG, which has been shown previously, was confirmed: A small subset of DIPG patients appeared to benefit from anti-EGFR antibody treatment.

A Multicenter, First-in-Pediatrics, Phase 1, Pharmacokinetic and Pharmacodynamic Study of Ridaforolimus in Patients with Refractory Solid Tumors

Purpose: Ridaforolimus (MK-8669, AP23573) is a potent and selective mammalian target of rapamycin (mTOR) inhibitor. Preclinically, ridaforolimus displays antiproliferative activity against a variety of human tumors in vitro and tumor xenograft models in vivo, with additive or synergistic activity when combined with other anticancer agents. Antitumor activity has been confirmed in adults. This phase I study determined the safety, pharmacological, biologic, and toxicity profiles of ridaforolimus in pediatric patients with refractory malignancies. Experimental Design: Eligible children ages 1 to 18 years with advanced solid tumors were enrolled in a 3 + 3 dose escalation design, to determine the safety, tolerability, and maximum tolerated dose (MTD)/dose-limiting toxicity (DLT) of ridaforolimus. Toxicities, pharmacokinetics, and pharmacodynamics were characterized. Results: Fifteen patients were treated. No DLT was observed at any dose level tested; therefore, an MTD was not identified. Most adverse events were mild to moderate; the most common grades 3 and 4 adverse events were hematologic, including thrombocytopenia and anemia. Nonhematologic adverse events were mostly electrolyte disturbances. The observed pharmacokinetic profile of ridaforolimus in children was consistent with that previously showed in adults. Pharmacodynamic confirms that the dose range tested has pharmacological/pharmacodynamic activity. Forty percent of patients achieved stable disease including four of six with central nervous system tumors and two of eight with sarcomas. Conclusions: This first-in-pediatrics study shows that the second-generation mTOR inhibitor ridaforolimus is well tolerated in heavily pretreated children with refractory solid tumors. No DLTs were observed over the dose range tested. Ridaforolimus may represent a therapeutic option for use in pediatric malignancies. Clin Cancer Res; 19(13); 3649–58. ©2013 AACR.

FUNCTIONAL SUBCLONE PROFILING FOR PREDICTION OF TREATMENT-INDUCED INTRA-TUMOR POPULATION SHIFTS AND DISCOVERY OF RATIONAL DRUG COMBINATIONS IN HUMAN GLIOBLASTOMA

Purpose: Investigation of clonal heterogeneity may be key to understanding mechanisms of therapeutic failure in human cancer. However, little is known on the consequences of therapeutic intervention on the clonal composition of solid tumors. Experimental Design: Here, we used 33 single cell–derived subclones generated from five clinical glioblastoma specimens for exploring intra- and interindividual spectra of drug resistance profiles in vitro. In a personalized setting, we explored whether differences in pharmacologic sensitivity among subclones could be employed to predict drug-dependent changes to the clonal composition of tumors. Results: Subclones from individual tumors exhibited a remarkable heterogeneity of drug resistance to a library of potential antiglioblastoma compounds. A more comprehensive intratumoral analysis revealed that stable genetic and phenotypic characteristics of coexisting subclones could be correlated with distinct drug sensitivity profiles. The data obtained from differential drug response analysis could be employed to predict clonal population shifts within the naïve parental tumor in vitro and in orthotopic xenografts. Furthermore, the value of pharmacologic profiles could be shown for establishing rational strategies for individualized secondary lines of treatment. Conclusions: Our data provide a previously unrecognized strategy for revealing functional consequences of intratumor heterogeneity by enabling predictive modeling of treatment-related subclone dynamics in human glioblastoma. Clin Cancer Res; 23(2); 562–74. ©2016 AACR.