Abstract P02-04: BDTX-1535, a CNS penetrant MasterKey inhibitor of common, uncommon and resistant EGFR mutations, demonstrates in vivo efficacy and has potential to treat osimertinib-resistant NSCLC with or without brain metastases

NSCLC accounts for approximately 85% of lung cancer cases worldwide. NSCLC harboring EGFR mutations constitutes 10-20% of all lung cancer cases in Europe and North America, and up to 50% of those in Asia. The majority (80-90%) of these mutations are either Exon19del or L858R. Uncommon EGFR mutations, of which G719X, S768I and L861Q are amongst the most frequent, account for 10-20% of EGFR mutations in NSCLC. Additionally, secondary EGFR mutations such as C797S that emerge during treatment with osimertinib occur in ~10% of patients. Current generation EGFR inhibitors with efficacy against common, uncommon and/or resistance mutations are either poorly brain penetrant or do not have broad spectrum activity against multiple mutations. BDTX-1535 is an irreversible, spectrum selective MasterKey inhibitor of common, uncommon and resistance EGFR mutations such as G719X and C797S that occur in NSCLC (IC50<10nM). BDTX-1535 is differentiated from many EGFR inhibitors by its CNS-penetrating properties. BDTX-1535 has a Kpuu, defined as the ratio of the unbound brain tissue concentration over the unbound plasma concentration, of 0.8 in rat. In studies of EGFR Exon19del+C797S, BDTX-1535 achieved pEGFR suppression exceeding 24 hours in vitro and following a single dose in vivo. BDTX-1535 has demonstrated robust tumor growth inhibition and regressions in multiple pre-clinical models, including PDX intracranial models. Thus, BDTX-1535 has potential to treat patients with NSCLC harboring a broad range of mutations, both common and uncommon, as well as those associated with resistance to the current standard of care TKIs. The CNS penetrating properties may help to treat CNS metastases or to prevent them from occurring. BDTX-1535 is currently being evaluated in IND-enabling studies.

Citation Format: Matthew C. Lucas, Melinda S. Merchant, Matthew O'Connor, Carl Cook, Sherri Smith, Anthony Trombino, Wu-Yan Zhang, Irache Visiers, Kate Tith, Reza Foroughi, Nigel Waters, Iwona Wrona, Michael Pickard, Sudharshan Eathiraj, Karsten Witt, Christopher Roberts, Rachel Humphrey, Elizabeth Buck. BDTX-1535, a CNS penetrant MasterKey inhibitor of common, uncommon and resistant EGFR mutations, demonstrates in vivo efficacy and has potential to treat osimertinib-resistant NSCLC with or without brain metastases [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P02-04.

Brain exposure of the ATM inhibitor AZD1390 in humans-a positron emission tomography study

BACKGROUND

The protein kinase ataxia telangiectasia mutated (ATM) mediates cellular response to DNA damage induced by radiation. ATM inhibition decreases DNA damage repair in tumor cells and affects tumor growth. AZD1390 is a novel, highly potent, selective ATM inhibitor designed to cross the blood-brain barrier (BBB) and currently evaluated with radiotherapy in a phase I study in patients with brain malignancies. In the present study, PET was used to measure brain exposure of 11C-labeled AZD1390 after intravenous (i.v.) bolus administration in healthy subjects with an intact BBB.

METHODS

AZD1390 was radiolabeled with carbon-11 and a microdose (mean injected mass 1.21 µg) was injected in 8 male subjects (21-65 y). The radioactivity concentration of [11C]AZD1390 in brain was measured using a high-resolution PET system. Radioactivity in arterial blood was measured to obtain a metabolite corrected arterial input function for quantitative image analysis. Participants were monitored by laboratory examinations, vital signs, electrocardiogram, adverse events.

RESULTS

The brain radioactivity concentration of [11C]AZD1390 was 0.64 SUV (standard uptake value) and reached maximum 1.00% of injected dose at Tmax[brain] of 21 min (time of maximum brain radioactivity concentration) after i.v. injection. The whole brain total distribution volume was 5.20 mL*cm-3. No adverse events related to [11C]AZD1390 were reported.

CONCLUSIONS

This study demonstrates that [11C]AZD1390 crosses the intact BBB and supports development of AZD1390 for the treatment of glioblastoma multiforme or other brain malignancies. Moreover, it illustrates the potential of PET microdosing in predicting and guiding dose range and schedule for subsequent clinical studies.

Results of the phase 1b soft-tissue sarcoma (STS) portion of the global randomized, double-blind, placebo-controlled study of tazemetostat (TAZ) plus doxorubicin (DOX) as frontline therapy for advanced epithelioid sarcoma (ES)

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Background: ES is a rare, aggressive subtype of STS for which cytotoxic chemotherapy has limited effectiveness. TAZ, an FDA-approved EZH2 inhibitor, has shown single-agent clinical activity and a favorable safety profile in patients with metastatic or locally advanced ES. In preclinical studies, TAZ has shown synergistic antitumor activity with DOX, which is often used as frontline treatment for STS. Here, we present results of the phase 1b study (NCT04204941), designed to assess the recommended phase 3 dose (RP3D), safety, and efficacy of TAZ + DOX in patients with advanced STS. Methods: The open-label, phase 1b portion of this study enrolled adult patients with previously untreated advanced STS. A standard 3 + 3 design was used to assess TAZ 400 mg, 600 mg, and 800 mg orally twice daily in combination with DOX (75 mg/m2 intravenously on day 1 of each cycle, for up to 6 cycles) as frontline therapy. Dose-limiting toxicities (DLTs) were predefined in the protocol. The RP3D of TAZ was determined by Scientific Review Committee review of the safety and pharmacokinetic data from the phase 1b trial, with a target DLT rate of < 33%. Results: As of February 1, 2021, 16 patients are enrolled, including 2 with ES; 10 are still receiving TAZ + DOX and 6 have discontinued (5 due to disease progression, 1 due to patient withdrawal). The median age was 49.5 years (range, 29–82) and all had unresectable STS. Median (range) time on treatment was 13 (0.1–51.1+) weeks across all dose levels evaluated. Two DLTs, both of febrile neutropenia, were observed, one in the TAZ 600 mg + DOX cohort (n = 1/6, 17%), and one in the TAZ 800 mg + DOX cohort (n = 1/3, 33%). When used in combination with DOX, the RP3D of TAZ was 800 mg. Grade 3 or 4 treatment-related treatment-emergent adverse events (TR-TEAEs) occurred in 13/16 (81.3%) patients. The most common (≥ 20%) TR-TEAEs were neutropenia (n = 11, 69%), anemia (n = 10, 63%), fatigue (n = 10, 63%), stomatitis (n = 9, 56%), nausea (n = 8, 50%), febrile neutropenia (n = 7, 44%), constipation (n = 6, 38%), vomiting (n = 6, 38%), and decreased appetite (n = 5, 31%). TR-TEAEs were defined as attributable to either study agent. Conclusions: The combination of TAZ + DOX was generally well tolerated in this dose finding study in patients with advanced STS. The RP3D to be tested in the phase 3 randomized, double blind, placebo controlled study is TAZ 800 mg twice daily + DOX. The safety profile of this combination is consistent with the respective safety information for TAZ and for DOX. The TR-TEAEs include known toxicities of DOX or TAZ. Further comparison with DOX + placebo in the phase 3 trial will aid in assessing efficacy and safety of the combination of TAZ + DOX. The global phase 3 confirmatory trial will enroll patients with ES who have unresectable disease and have had no prior systemic therapy. Clinical trial information: NCT04204941.

Pediatric PK/PD Phase I Trial of Pexidartinib in Relapsed and Refractory Leukemias and Solid Tumors Including Neurofibromatosis Type I-Related Plexiform Neurofibromas

PURPOSE

Simultaneously targeting the tumor and tumor microenvironment may hold promise in treating children with refractory solid tumors. Pexidartinib, an oral inhibitor of tyrosine kinases including colony stimulating factor 1 receptor (CSF-1R), KIT, and FLT3, is FDA approved in adults with tenosynovial giant cell tumor. A phase I trial was conducted in pediatric and young adult patients with refractory leukemias or solid tumors including neurofibromatosis type 1-related plexiform neurofibromas.

PATIENTS AND METHODS

A rolling six design with dose levels (DL) of 400 mg/m², 600 mg/m², and 800 mg/m² once daily for 28-day cycles (C) was used. Response was assessed at regular intervals. Pharmacokinetics and population pharmacokinetics were analyzed during C1.

RESULTS

Twelve patients (4 per DL, 9 evaluable) enrolled on the dose-escalation phase and 4 patients enrolled in the expansion cohort: median (lower, upper quartile) age 16 (14, 16.5) years. No dose-limiting toxicities were observed. Pharmacokinetics appeared linear over three DLs. Pharmacokinetic modeling and simulation determined a weight-based recommended phase II dose (RP2D). Two patients had stable disease and 1 patient with peritoneal mesothelioma (C49+) had a sustained partial response (67% RECIST reduction). Pharmacodynamic markers included a rise in plasma macrophage CSF (MCSF) levels and a decrease in absolute monocyte count.

CONCLUSIONS

Pexidartinib in pediatric patients was well tolerated at all DL tested, achieved target inhibition, and resulted in a weight-based RPD2 dose.

A phase I, open-label, multicenter study to assess the safety, pharmacokinetics, and preliminary antitumor activity of AZD4635 both as monotherapy and in combination in patients with advanced solid malignancies: Results from prostate cancer patients (NCT02740985)

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Background: AZD4635 inhibits adenosine 2a receptor (A2aR) signaling and improves immune activation and anti-tumor activity in preclinical models. This phase I study assessed the safety, pharmacokinetics, pharmacodynamics and efficacy of AZD4635 monotherapy (mono) and in combination (combo) with durvalumab (durva) in patients (pts) with refractory solid tumors. Here we present data for immune checkpoint-naïve pts with metastatic castrate-resistant prostate cancer (mCRPC). Methods: Pts with refractory mCRPC received AZD4635 mono (75 mg or 100 mg QD oral nanosuspension [(RP2D]) or in combination (75 mg or 100mg QD) with durva 1.5g IV q4wk. Results: Between 30Aug16 and 20Jun19 (data cutoff [DCO]) 94 mCRPC pts were treated with mono (n = 49) or combo (n = 45): median age 70.5 yrs; ECOG 0-1 = 99%. The median number of prior treatment regimens was 5 (range = 1-10); 61% of pts (57/94) had prior chemotherapy, 90% had prior new hormonal therapy. PK data suggest AZD4635 concentrations at 75-100 mg QD are above the in vitro IC50 for A2aR inhibition throughout the dosing interval. Modeling predicts 80-90% A2aR occupancy at steady state for doses at ≥75 mg QD. Most common treatment-related AEs ( > 10%) were nausea, vomiting, fatigue, decreased appetite, dizziness, and diarrhea. At the DCO in this ongoing study, 70 pts were evaluable for response by RECIST v1.1 (mono = 33, combo = 37). Confirmed response occurred in 8 pts: mono = ORR 6.1% (2PRs) and combo = 16.2% (2CRs, 4PRs). The duration of response across cohorts ranged from 1-18.5 mo (5 pts ongoing). PSA response (defined as ≥50% decrease from baseline of ≥1ng/ml) was observed in 6.4% (3/47 pts; 95% CI, 1.3-17.5) of mono-treated patients and 20% (9/45 pts; 95% CI, 9.6-34.6) of combo-treated patients. Patients with high adenosine (ADO) gene expression signature (N = 46) in peripheral blood, showed a median PFS of 21 weeks v. 8.7 weeks in ADO signature low patients (N = 46) (HR 0.5, CI 0.3-0.9) (DCO 20Jun19). In addition, baseline TCR clonality and diversity were linked with response. Conclusions: In mCRPC pts, AZD4635 alone or in combination with durva was tolerable and associated with clinical benefit. A mCRPC phase II trial is ongoing with continued exploration of predictors of response to treatment. Clinical trial information: NCT02740985 .

Nivolumab in children and young adults with relapsed or refractory solid tumours or lymphoma (ADVL1412): a multicentre, open-label, single-arm, phase 1-2 trial

BACKGROUND

Immune checkpoint inhibitors targeting PD-1 have shown clinical benefit in adults with cancer, but data on these drugs in children are scarce. We did a phase 1-2 study of nivolumab, a PD-1 blocking monoclonal antibody, to determine its safety, pharmacokinetics, and antitumour activity in children and young adults with recurrent or refractory non-CNS solid tumours or lymphoma.

METHODS

We did a multicentre, open-label, single-arm, dose-confirmation and dose-expansion, phase 1-2 trial in 23 hospitals in the USA. Eligible patients for part A (dose-confirmation phase) of the study were aged 1-18 years with solid tumours with measurable or evaluable disease (by Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) regardless of histology. Eligible patients for part B (dose-expansion phase) were aged 1-30 years with measurable disease (by RECIST criteria) in the following disease cohorts: rhabdomyosarcoma, Ewing sarcoma, osteosarcoma, neuroblastoma, Hodgkin lymphoma, non-Hodgkin lymphoma, and melanoma. Patients in part A and were given nivolumab 3 mg/kg intravenously over 60 min on days 1 and 15 of a 28-day cycle in a rolling 6 study design with de-escalation upon dose-limiting toxicities to establish the recommended phase 2 dose. Patients in part B were given the recommended phase 2 dose. The primary outcomes were the tolerability, systemic exposure, maximum tolerated dose, and the antitumour activity of nivolumab at the adult recommended dose in children and young adults. This trial is registered with ClinicalTrials.gov, NCT02304458, with follow-up ongoing and is closed to new participants.

FINDINGS

85 patients were enrolled between Feb 22, 2015, and Dec 31, 2018, and 75 patients were fully evaluable for toxicity. Median follow-up was 30 days (IQR 27-83). In part A, 13 patients were enrolled and 12 were evaluable for toxicity. There were no dose de-escalations or dose-limiting toxicities and nivolumab 3 mg/kg was confirmed as the paediatric recommended phase 2. 72 patients were enrolled in part B and 63 were evaluable for toxicity. Five (7%) patients in part B had dose-limiting toxicities. The most common overall toxicity was anaemia (35 [47%] of 75 patients; five patients had grade 3 or grade 4) and non-haematological toxicity was fatigue (28 [37%] patients; none had grade 3 or grade 4). Responses were observed in patients with lymphoma (three [30%] of ten with Hodgkin lymphoma and one [10%] of ten with non-Hodgkin lymphoma; all responders had PD-L1 expression). Objective responses were not observed in other tumour types.

INTERPRETATION

Nivolumab was safe and well tolerated in children and young adults and showed clinical activity in lymphoma. Nivolumab showed no significant single-agent activity in the common paediatric solid tumours. This study defines the recommended phase 2 dose and establishes a favourable safety profile for nivolumab in children and young adults, which can serve as the basis for its potential study in combinatorial regimens for childhood cancer.

FUNDING

Bristol-Myers Squibb, Children's Oncology Group, National Institutes of Health, Cookies for Kids Cancer Foundation.

Antitumor Activity Associated with Prolonged Persistence of Adoptively Transferred NY-ESO-1 c259T Cells in Synovial Sarcoma

We evaluated the safety and activity of autologous T cells expressing NY-ESO-1^c259, an affinity-enhanced T-cell receptor (TCR) recognizing an HLA-A2-restricted NY-ESO-1/LAGE1a-derived peptide, in patients with metastatic synovial sarcoma (NY-ESO-1^c259T cells). Confirmed antitumor responses occurred in 50% of patients (6/12) and were characterized by tumor shrinkage over several months. Circulating NY-ESO-1^c259T cells were present postinfusion in all patients and persisted for at least 6 months in all responders. Most of the infused NY-ESO-1^c259T cells exhibited an effector memory phenotype following ex vivo expansion, but the persisting pools comprised largely central memory and stem-cell memory subsets, which remained polyfunctional and showed no evidence of T-cell exhaustion despite persistent tumor burdens. Next-generation sequencing of endogenous TCRs in CD8⁺ NY-ESO-1^c259T cells revealed clonal diversity without contraction over time. These data suggest that regenerative pools of NY-ESO-1^c259T cells produced a continuing supply of effector cells to mediate sustained, clinically meaningful antitumor effects.Significance: Metastatic synovial sarcoma is incurable with standard therapy. We employed engineered T cells targeting NY-ESO-1, and the data suggest that robust, self-regenerating pools of CD8⁺ NY-ESO-1^c259T cells produce a continuing supply of effector cells over several months that mediate clinically meaningful antitumor effects despite prolonged exposure to antigen. Cancer Discov; 8(8); 944-57. ©2018 AACR.See related commentary by Keung and Tawbi, p. 914This article is highlighted in the In This Issue feature, p. 899.

Vincristine Sulfate Liposomes Injection (VSLI, Marqibo®): Results From a Phase I Study in Children, Adolescents, and Young Adults With Refractory Solid Tumors or Leukemias

BACKGROUND

Vincristine sulfate liposome injection (VSLI; Marqibo®) is an encapsulated preparation of standard vincristine in sphingomyelin/cholesterol liposomes. Clinical trials in adults have demonstrated safety, tolerability, and activity, leading to Food and Drug Administration (FDA) approval for adults with relapsed acute lymphoblastic leukemia (ALL). Pediatric experience with VSLI is limited.

PROCEDURE

This single center, phase I dose escalation study examined the safety, toxicity, maximum tolerated dose, and pharmacokinetics of VSLI administered weekly to pediatric patients age <21 years with relapsed or chemotherapy-refractory solid tumors or leukemia.

RESULTS

Twenty-one subjects were treated in total. Median age was 13.3 years (range 2-19). Fourteen subjects completed one 28-day cycle of therapy and five subjects completed more than one cycle. No subject experienced dose-limiting toxicity (DLT) at the first dose level (1.75 mg/m(2) /dose, dose range: 2-3.7 mg). At the second dose level (2.25 mg/m(2) /dose, dose range: 1.3-4.5 mg), one subject had transient dose-limiting grade 4 transaminase elevation, and this dose level was expanded with no additional DLT observed. The second dose level then opened to an expansion phase to evaluate activity in ALL. Clinical activity included minimal residual disease negative complete remission in one subject with ALL and stable disease in nine subjects. Clearance of total vincristine was found to be approximately 100-fold lower in comparison to published data using standard vincristine.

CONCLUSIONS

Children tolerate 2.25 mg/m(2) /dose of weekly VSLI (the adult FDA-approved dose) with evidence for clinical activity without dose-limiting neurotoxicity. Future plans include studying VSLI as substitution for standard vincristine with combination chemotherapy in children with ALL.

Myeloid cells in peripheral blood mononuclear cell concentrates inhibit the expansion of chimeric antigen receptor T cells

BACKGROUND AIMS

Autologous chimeric antigen receptor (CAR) T-cell therapies have shown promising clinical outcomes, but T-cell yields have been variable. CD19- and GD2-CAR T-cell manufacturing records were reviewed to identify sources of variability.

METHODS

CD19-CAR T cells were used to treat 43 patients with acute lymphocytic leukemia or lymphoma and GD2-CAR T cells to treat eight patients with osteosarcoma and three with neuroblastoma. Both types of CAR T cells were manufactured using autologous peripheral blood mononuclear cells (PBMC) concentrates and anti-CD3/CD28 beads for T-cell enrichment and simulation.

RESULTS

A comparison of the first 6 GD2- and the first 22 CD19-CAR T-cell products manufactured revealed that GD2-CAR T-cell products contained fewer transduced cells than CD19-CAR T-cell products (147 ± 102 × 10(6) vs 1502 ± 1066 × 10(6); P = 0.0059), and their PBMC concentrates contained more monocytes (31.4 ± 12.4% vs 18.5 ± 13.7%; P = 0.019). Among the first 28 CD19-CAR T-cell products manufactured, four had poor expansion yielding less than 1 × 10(6) transduced T cells per kilogram. When PBMC concentrates from these four patients were compared with the 24 others, PBMC concentrates of poorly expanding products contained greater quantities of monocytes (39.8 ± 12.9% vs. 15.3 ± 10.8%, P = 0.0014). Among the patients whose CD19-CAR T cells expanded poorly, manufacturing for two patients was repeated using cryopreserved PBMC concentrates but incorporating a monocyte depleting plastic adherence step, and an adequate dose of CAR T cells was produced for both patients.

CONCLUSIONS

Variability in CAR T-cell expansion is due, at least in part, to the contamination of the starting PBMC concentrates with monocytes.

MultiDimensional ClinOmics for Precision Therapy of Children and Adolescent Young Adults with Relapsed and Refractory Cancer: A Report from the Center for Cancer Research

PURPOSE

We undertook a multidimensional clinical genomics study of children and adolescent young adults with relapsed and refractory cancers to determine the feasibility of genome-guided precision therapy.

EXPERIMENTAL DESIGN

Patients with non-central nervous system solid tumors underwent a combination of whole exome sequencing (WES), whole transcriptome sequencing (WTS), and high-density single-nucleotide polymorphism array analysis of the tumor, with WES of matched germline DNA. Clinically actionable alterations were identified as a reportable germline mutation, a diagnosis change, or a somatic event (including a single nucleotide variant, an indel, an amplification, a deletion, or a fusion gene), which could be targeted with drugs in existing clinical trials or with FDA-approved drugs.

RESULTS

Fifty-nine patients in 20 diagnostic categories were enrolled from 2010 to 2014. Ages ranged from 7 months to 25 years old. Seventy-three percent of the patients had prior chemotherapy, and the tumors from these patients with relapsed or refractory cancers had a higher mutational burden than that reported in the literature. Thirty patients (51% of total) had clinically actionable mutations, of which 24 (41%) had a mutation that was currently targetable in a clinical trial setting, 4 patients (7%) had a change in diagnosis, and 7 patients (12%) had a reportable germline mutation.

CONCLUSIONS

We found a remarkably high number of clinically actionable mutations in 51% of the patients, and 12% with significant germline mutations. We demonstrated the clinical feasibility of next-generation sequencing in a diverse population of relapsed and refractory pediatric solid tumors. Clin Cancer Res; 22(15); 3810-20. ©2016 AACR.

Adjuvant Immunotherapy to Improve Outcome in High-Risk Pediatric Sarcomas

PURPOSE

Patients with metastatic or relapsed pediatric sarcomas receive cytotoxic regimens that induce high remission rates associated with profound lymphocyte depletion, but ultimately few survive long term. We administered adjuvant immunotherapy to patients with metastatic and recurrent pediatric sarcomas in an effort to improve outcomes.

EXPERIMENTAL DESIGN

Mononuclear cells were collected via apheresis, and tumor lysate was acquired via percutaneous biopsy at enrollment. Participants received standard antineoplastic therapy, followed by autologous lymphocytes, tumor lysate/keyhole limpet hemocyanin-pulsed dendritic cell vaccinations ± recombinant human IL7. Primary outcomes were toxicity and vaccine responses. Secondary outcomes were immune reconstitution, event-free survival, and overall survival (OS).

RESULTS

Forty-three patients enrolled and 29 received immunotherapy. The regimen was well tolerated. Intent-to-treat analysis demonstrated 5-year OS of 51% with significant differences based upon histologic group (63% vs. 0% for Ewing/rhabdomyosarcoma vs. other sarcomas) and response to standard therapy (74% no residual disease vs. 0% residual disease). Five-year intent-to-treat OS of patients with newly diagnosed metastatic Ewing/rhabdomyosarcoma was 77%, higher than previously reported in this population and higher than observed in a similar group treated with an earlier adjuvant immunotherapy regimen (25% 5-year OS). T-cell responses to autologous tumor lysate were identified in 62% of immunotherapy recipients, and survival was higher in those patients (73% 5-year OS with vs. 37% without immune response, P = 0.017). Immune reconstitution, measured by CD4 count recovery, was significantly enhanced in subjects treated with recombinant human IL7.

CONCLUSIONS

Adjuvant immunotherapy may improve survival in patients with metastatic pediatric sarcoma. Clin Cancer Res; 22(13); 3182-91. ©2016 AACR.

Phase I Clinical Trial of Ipilimumab in Pediatric Patients with Advanced Solid Tumors

PURPOSE

Ipilimumab is a first-in-class immune checkpoint inhibitor approved for treatment of metastatic melanoma but not studied in children until this phase I protocol.

EXPERIMENTAL DESIGN

This study examined safety, pharmacokinetics, and immunogenicity, and immune correlates of ipilimumab administered to subjects ≤21 years old with recurrent or progressive solid tumors. Dose escalation cohorts received 1, 3, 5, or 10 mg/m(2) intravenously every 3 weeks in a 3 + 3 design. Response was assessed after 6 weeks and 12 weeks, and then every 3 months. Treatment was continued until disease progression or unacceptable toxicity.

RESULTS

Thirty-three patients received 72 doses of ipilimumab. Patients enrolled had melanoma (n = 12), sarcoma (n = 17), or other refractory solid tumors (n = 4). Immune-related adverse events included pancreatitis, pneumonitis, colitis, endocrinopathies, and transaminitis with dose-limiting toxicities observed at 5 and 10 mg/kg dose levels. Pharmacokinetics revealed a half-life of 8 to 15 days. At day 21, subjects had increased levels of cycling T cells, but no change in regulatory T-cell populations. Six subjects had confirmed stable disease for 4 to 10 cycles (melanoma, osteosarcoma, clear cell sarcoma, and synovial sarcoma).

CONCLUSIONS

Ipilimumab was safely administered to pediatric patients using management algorithms for immune-related toxicities. The spectrum of immune-related adverse events is similar to those described in adults; however, many of the pediatric toxicities were evident after a single dose. Although no objective tumor regressions were observed with ipilimumab as a single agent, subjects with immune-related toxicities had an increased overall survival compared with those who showed no evidence of breaking tolerance.

Abstract 3882: Clinical exome and transcriptome sequencing for identification of actionable cancer targets: A pilot study for children and young adults with relapsed or refractory solid tumors

Background. With technological advances such as next-generation sequencing, recent gains in understanding pediatric cancer can aid in treatment decisions, especially in the setting of relapse. To discover expressed, clinically significant mutations for pediatric patients with relapsed tumors, we performed a pilot trial using a combination of whole exome sequencing (WES) of tumor/normal DNA and whole transcriptome sequencing (WTS) of tumors, complemented by single nucleotide polymorphism (SNP) arrays.

Objectives. We identified 48 pediatric and young adult patients with relapsed or refractory solid tumors with matched tumor/normal samples. Our goals were to determine the feasibility of performing comprehensive genomic analyses in this population, to compare the genomic profile of relapsed tumors to prior reports of primary tumors, and to delineate the percentage of patients with actionable mutations. Actionable changes were defined as reportable germ line mutations determined by the American College of Medical Genetics (ACMG), a change in diagnosis, and somatic changes targetable by FDA approved medications or drugs undergoing clinical trials.

Methods. WES was performed on matched tumor and normal samples to identify germ line and somatic mutations. WTS was performed on tumor samples to identify fusion genes, gene expression profiling, and expressed variants. SNP arrays were performed to identify copy number changes. Sanger validation confirmed reportable mutations.

Results. In the exome, we noted a median of 33 somatic mutations per sample (range 1-375), a higher mutational burden compared to previously reported primary pediatric malignancies. Transcriptome data further refined results to a median of 7 expressed somatic mutations per sample (range 0-95). The majority of patients had one oncogenic driver. Sequencing relapsed tumors at multiple time points showed the continued presence of driver mutations but a shift in passenger mutations. Eleven of the 48 patients (23%) had a targetable mutation, such as ALK, BRAF, GNAQ, GNA11, IDH1, MTOR, PIK3CA, and SKP2. Two patients (4%) had a change in diagnosis due to the presence or absence of diagnostic fusion genes. In the germ line of 5 patients (10%) we discovered mutations in ACMG-reportable genes MUTYH, SCN5A, TP53, and MLH1. A total of 16 patients (33%) had actionable mutations.

Conclusions. Our study showed the feasibility of next-generation sequencing in relapsed pediatric solid tumors, with actionable mutations detected in a third of our patients. We demonstrated the utility in using exome and transcriptome sequencing with SNP arrays. Implementation of these techniques has the potential to change the practice of precision medicine. In summary, we have developed a prototype that will be utilized to design a national Pediatric Match trial in collaboration with the Children's Oncology Group. 

Citation Format: Wen-I Chang, Andrew S. Brohl, Rajesh Patidar, Jack F. Shern, Jun S. Wei, Young K. Song, Hongling Liao, Jimmy Lin, Sivasish Sindiri, Li Chen, Berkley Gryder, Marielle E. Yohe, Shile Zhang, Melinda S. Merchant, Brigitte C. Widemann, Javed Khan. Clinical exome and transcriptome sequencing for identification of actionable cancer targets: A pilot study for children and young adults with relapsed or refractory solid tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3882. doi:10.1158/1538-7445.AM2015-3882

Survival in metastatic Ewing sarcoma (EWS) and rhabdomyosarcoma (RMS) following consolidation immunotherapy with autologous lymphocyte infusion, dendritic cell vaccines ± CYT107 (rhIL-7)

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Background: Higher lymphocyte levels correlate with better survival in a variety of cancers, but it remains unclear whether there is a causal relationship between immune function and survival in cancer patients. A pilot study in high-risk pediatric sarcomas was undertaken to determine if a regimen designed to enhance immune reconstitution following standard cytotoxic therapy could improve survival. Methods: Forty-four patients (median 16 yrs, range 5-33) enrolled following a diagnosis of metastatic or late recurrent pediatric sarcoma, and underwent apheresis to collect mononuclear cells and tumor biopsy to generate tumor lysate, then received standard therapy at their home institution. After standard therapy, 29 patients received immunotherapy, comprising a single infusion of autologous lymphocytes depleted of CD4+CD25+regulatory T cells, plus dendritic cell vaccines pulsed with autologous tumor lysate and keyhole limpet hemocyanin (KLH, Q14d x 6). After the first 5 patients, CYT107 (rhIL-7, 20 mcg/kg SQ Q14d x 4) was added to the regimen. Intensive biologic analyses measured global and regulatory T cell immune reconstitution and vaccine responses. Results: This outpatient regimen was well tolerated with toxicities limited to rash, low-grade fever and mild constitutional symptoms. CYT107 dramatically enhanced global immune reconstitution and diminished regulatory T cell frequency. All patients developed immune responses to KLH and 31% developed immune responses to tumor lysate. Intent-to-treat analysis of all patients enrolled shows 56% 5-yr OS, with immunotherapy recipients having a 64% 5-yr OS (median f/u 30 mos, range 23-65). Intent-to-treat analysis of the subset of patients enrolled at the time of a new diagnosis of metastatic EWS or RMS shows 83% 5-yr OS and 54% 5-yr EFS (n=13, median f/u 35 mos, range 24-63), which is superior to previous outcomes reported for this population. Conclusions: A low intensity immunotherapy regimen focused on enhancing immune reconstitution following standard therapy may diminish recurrence in newly diagnosed metastatic EWS and RMS. Clinical trial information: NCT00923351.

Phase I trial and pharmacokinetic study of lexatumumab in pediatric patients with solid tumors

PURPOSE

Lexatumumab is an agonistic, fully human monoclonal antibody against tumor necrosis factor-related apoptosis-inducing ligand receptor 2 with preclinical evidence of activity in pediatric solid tumors.

PATIENTS AND METHODS

This phase I dose-escalation study examined the safety, tolerability, pharmacokinetics, and immunogenicity of lexatumumab at doses up to, but not exceeding, the adult maximum-tolerated dose (3, 5, 8, and 10 mg/kg), administered once every 2 weeks to patients age≤21 years with recurrent or progressive solid tumors.

RESULTS

Twenty-four patients received a total of 56 cycles of lexatumumab over all four planned dose levels. One patient had grade 2 pericarditis consistent with radiation recall, and one patient developed grade 3 pneumonia with hypoxia during the second cycle. Five patients experienced stable disease for three to 24 cycles. No patients experienced complete or partial response, but several showed evidence of antitumor activity, including one patient with recurrent progressive osteosarcoma who experienced resolution of clinical symptoms and positron emission tomography activity, ongoing more than 1 year off therapy. One patient with hepatoblastoma showed a dramatic biomarker response.

CONCLUSION

Pediatric patients tolerate 10 mg/kg of lexatumumab administered once every 14 days, the maximum-tolerated dose identified in adults. The drug seems to mediate some clinical activity in pediatric solid tumors and may work with radiation to enhance antitumor effects.

Ipilimumab: First results of a phase I trial in pediatric patients with advanced solid tumors

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Background: Ipilimumab is a fully-human IgG1 monoclonal anti-CTLA-4 antibody which has been approved by the FDA for adult patients with metastatic melanoma . Although the approved dose is 3mg/kg every 21 days, the dose of 10mg/kg IV every 21 days for 4 doses in combination with chemotherapy was well tolerated in a phase III trial enrolling adult patients with melanoma. Methods: This pediatric phase I, dose escalation study examined the safety, tolerability, pharmacokinetics, and immunogenicity of ipilimumab administered to patients <21yo with recurrent or progressive solid tumors. Ipilimumab was administered at 1, 3, 5, and 10mg/kg IV in a standard 3 + 3 design with 4 doses of induction therapy q3 weeks followed by maintenance q3 months until disease progression or unacceptable toxicity. Tumors were measured after 6 weeks, 12 weeks, and then every 3 months. Results: Twenty one patients (melanoma n=6, osteosarcoma n=6, soft tissue sarcomas n=7, neuroblastoma, and renal cell carcinoma) received a total of 57 doses of Ipilimumab to date. One of 6 patients treated at 5mg/kg developed a dose-limiting grade 3 pancreatitis. .At the highest dose level of 10mg/kg, two of three patients under 12yo developed DLT: grade 3 colitis and concurrent norovirus in one patient, and self-resolving grade 3 transaminitis in a second patient. Three of three patients between the ages of 12 and 21yo tolerated the 10mg/kg dosing schedule without DLT. Across all dose levels, grade 2 or 3 adverse events included colitis (n=1), transaminitis (n=3), pancreatitis (n=1), autoimmune thyroiditis (n=2), and hypophysitis (n=1) observed between C1D8 and C4D21. A single grade 1 rash was observed. Stable disease was the best response in 5 patients with a duration of 3 to 18 months. Conclusions: Ipilimumab can be safely administered to pediatric patients. Adolescents are able to tolerate the highest dose of 10mg/kg. Younger children (<12yo) had 2 DLTs in 3 patients at 10 mg/kg . Expansion of the 10 mg/kg cohort for adolescents and of the 5 mg/kg dose for the <12yo for further safety and pharmacokinetic information is underway. The spectrum of adverse events appears similar to those described in the adult trials, although there were no grade 2 or higher incidents of rash.

Irinotecan and temozolomide for Ewing sarcoma: the Memorial Sloan-Kettering experience

BACKGROUND

The prognosis for recurrent/progressive Ewing sarcoma (ES) remains poor. Pre-clinical, adult phase I and II trials have demonstrated the combination of irinotecan and temozolomide to have schedule-dependent synergy and significant antitumor activity. A pediatric phase I trial has shown this regimen to be safe and active in advanced ES.

PROCEDURE

We conducted a retrospective chart review to identify patients with recurrent/progressive ES treated with irinotecan [20 mg/m(2)/day x 5(x2)] and temozolomide (100 mg/m(2)/day x 5) in our institution. The best response achieved, time to progression (TTP), and associated toxicities were recorded.

RESULTS

Twenty patients received a total of 154 cycles of therapy. Of 19 evaluable patients, there were 5 complete and 7 partial responses (a 63% overall objective response). Median TTP for 20 evaluable patients with recurrent/progressive ES was 8.3 months; for the subset of 14 patients with recurrent ES, it was 16.2 months. Median TTP was better for patients who sustained a 2-year first remission than for those who relapsed < 24 months from diagnosis and for patients with primary localized vs. metastatic disease. Significant toxicities included grade 3 diarrhea (7 cycles), grade 3 colitis (1 cycle), grade 3 pneumonitis in one patient receiving concurrent whole-lung RT, grade 3-4 neutropenia (19 cycles), and grade 3-4 thrombocytopenia (16 cycles).

CONCLUSIONS

Irinotecan and temozolomide is a well-tolerated and active regimen for recurrent/progressive ES. Prospective trials are necessary to define the role of this regimen in newly diagnosed ES.

Current approach to pediatric soft tissue sarcomas

The development of a new soft tissue lesion in an otherwise healthy child, adolescent, or young adult can present many challenges for pediatric or medical oncology teams. Although uncommon, the diagnosis of a soft tissue malignancy should always be considered in the differential diagnosis of persistent pain, even if no mass is palpable. The definitive diagnosis and treatment of a soft tissue mass is aided by timely scans, appropriate biopsy for anatomic and molecular pathology, and a treatment approach guided by the specific diagnosis. Because pediatric soft tissue sarcomas are rare, cooperative groups play a crucial role in defining the standard of care through retrospective series and well-designed prospective clinical trials. Enrollment of newly diagnosed patients in clinical studies should be encouraged in order to continue to improve outcomes and understanding of these rare tumors. This review focuses on the current recommendations for management of sarcomas that typically occur in the soft tissues of pediatric and young adult patients.

Interleukin 7 signaling in dendritic cells regulates the homeostatic proliferation and niche size of CD4+ T cells

Interleukin 7 (IL-7) and T cell receptor (TCR) signals have been proposed to be the primary drivers of homeostatic T cell proliferation. However, it is not known why CD4⁺ T cells undergo less efficient homeostatic proliferation than CD8⁺ T cells. Here we showed that systemic IL-7 concentrations rise during lymphopenia due to diminished IL-7 utilization, but that IL-7 signaling on IL-7Rα⁺ dendritic cells (DCs) in lymphopenic settings paradoxically diminishes CD4⁺ T cell homeostatic proliferation. This effect is mediated, at least in part, by IL-7-mediated downregulation of MHC class II expression on IL-7Rα⁺ DCs. These results implicate IL-7Rα⁺ DCs as regulators of the peripheral CD4⁺ T cell niche, and indicate that IL-7 signals in DCs prevent uncontrolled CD4⁺ T cell expansion in vivo.

Immune reconstitution prevents metastatic recurrence of murine osteosarcoma

Primary tumors developing in immunocompetent hosts escape immunosurveillance by acquiring immune evasive properties. This raises the prospect that metastases derived from such tumors will also evade immunity. To investigate whether immune surveillance plays a role in preventing metastases, we studied a murine model which mimics the clinical progression of osteosarcoma: primary tumor growth in the lower extremity, amputation, minimal residual disease followed by the development of overt metastases. K7M2 implants readily escaped immune surveillance since normal BALB/c mice, T cell deficient SCID and T/NK cell deficient SCID-bg mice showed no difference in the rate of growth of primary osteosarcomas. However, both SCID and SCID-bg mice had higher rates of metastases than immunocompetent mice. Similarly, immune reconstitution following transfer of naive T cells to SCID or SCID-bg mice did not impact primary tumor growth, but significantly diminished metastatic recurrence. T cells in osteosarcoma bearing mice produced IFNgamma in response to tumor and IFNgamma production by immune reconstituting T cells was required to prevent metastases. These results demonstrate an important role for T cell based immune surveillance in preventing metastases, even when metastases develop from tumors that adeptly evade immunosurveillance. The results further suggest that T cell depleting cancer therapies may eliminate beneficial immune responses and that immune reconstitution of lymphopenic cancer patients could prevent metastatic recurrence of solid tumors.

Interferon gamma enhances the effectiveness of tumor necrosis factor-related apoptosis-inducing ligand receptor agonists in a xenograft model of Ewing's sarcoma

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces selective apoptosis in a variety of tumors, including most cell lines derived from Ewing's sarcoma family of tumors, an aggressive sarcoma that afflicts children and young adults. To determine the in vivo efficacy of TRAIL receptor agonists in Ewing's sarcoma family of tumors, mice with orthotopic xenografts were treated with anti-TRAIL-R2 monoclonal antibody or TRAIL/Apo2L in a model that can identify effects on both primary tumors and metastases. Administration of either agonist slowed tumor growth in 60% of animals and induced durable remissions in 11 to 19% but did not alter the incidence of metastatic disease. Response rates were not improved by concurrent doxorubicin treatment. Cells recovered from both TRAIL receptor agonist-treated and nontreated tumors were found to be resistant to TRAIL-induced death in vitro unless pretreated with interferon (IFN) gamma. This resistance coincided with a selective down-regulation of TRAIL receptor expression on tumor cells. In vivo treatment with IFNgamma increased tumor expression of TRAIL receptors and caspase 8, but did not increase the antitumor effect of TRAIL receptor agonists on primary tumors. However, IFNgamma treatment alone or in combination with a TRAIL receptor agonist significantly decreased the incidence of metastatic disease and the combination of TRAIL receptor agonist therapy with IFNgamma-mediated impressive effects on both primary tumors and metastatic disease. These data demonstrate that in vivo growth favors TRAIL resistance but that TRAIL receptor agonists are active in Ewing's sarcoma family of tumors and that the combination of TRAIL receptor agonists with IFNgamma is a potent regimen in this disease capable of controlling both primary and metastatic tumors.

Effect of Imatinib Mesylate on Neuroblastoma Tumorigenesis and Vascular Endothelial Growth Factor Expression

BACKGROUND

Alternative treatment options are needed for advanced neuroblastoma patients because their prognosis remains poor after intensive chemotherapy. Neuroblastoma cells express platelet-derived growth factor (PDGF), stem cell factor (SCF), and vascular endothelial growth factor (VEGF) and their respective receptors, PDGFR, c-Kit, and Flk-1. We therefore evaluated the effects of imatinib mesylate (imatinib), a selective inhibitor of the tyrosine kinase activities of c-Kit and PDGFR, on the growth of neuroblastoma cells in vivo and in vitro.

METHODS

We tested seven human neuroblastoma cell lines for their sensitivity to imatinib. Cell viability was assessed by trypan blue dye exclusion. Apoptosis was evaluated by nuclear staining, flow cytometry, and western blotting. Protein assays included immunoprecipitation, western blotting, enzyme-linked immunosorbent assays, and immunohistochemistry. mRNA expression was assessed by northern blotting. We used a xenograft model in SCID mice (10 mice per group) to evaluate the effects of imatinib oral therapy (50 or 100 mg/kg every 12 hours for 14 days) on neuroblastoma tumor growth. All statistical tests were two-sided.

RESULTS

All seven neuroblastoma cell lines treated with imatinib displayed concentration-dependent decreases in cell viability, which coincided with an induction of apoptosis, and with ligand-stimulated phosphorylation of c-Kit and PDGFR. The imatinib concentrations that caused 50% inhibition of growth and 50% inhibition of ligand-induced phosphorylation of these receptors were 9-13 micro M and 0.1-0.5 microM, respectively. Expression of VEGF, but not phosphorylation of Flk-1, its receptor, was reduced in neuroblastoma cells treated with imatinib at 10 microM or higher. Mice treated with imatinib at 50 mg/kg or 100 mg/kg had statistically significantly smaller tumors than control mice treated with vehicle (mean tumor volume in mice treated with imatinib at 50 mg/kg = 1546 mm3, in control mice = 2954 mm3; difference = 1408 mm3, 95% confidence interval [CI] = 657 to 2159 mm3; P<.001; mean tumor volume in mice treated with imatinib at 100 mg/kg = 463 mm3; difference = 2491 mm3, 95% CI = 1740 to 3242 mm3; P<.001).

CONCLUSIONS

Imatinib inhibited the growth of neuroblastoma cells in vitro and in vivo. This inhibition was associated with suppression of PDGFR and c-Kit phosphorylation and inhibition of VEGF expression.

Tumor Expression of 4-1BB Ligand Sustains Tumor Lytic T Cells

Inadequate costimulation by solid tumors is generally believed to induce immune tolerance during primary tumor growth. We looked for tumor-specific immunity vs. tolerance in patients with Ewing's sarcoma. Circulating T cells from patients with progressively growing Ewing's tumors displayed MHC restricted tumor-induced proliferation and robust tumor lysis. Tumor-reactive T cells reside within the memory CD3+CD8+ subset and are CD28-/4-1BB+. Autologous Ewing's tumors expressed 4-1BBL, and tumor-induced T cell proliferation and activation required costimulation by 4-1BBL. Stimulation of PBL with anti-CD3/4-1BBL, but not anti-CD3/anti-CD28 induced tumor lytic effectors. Similarly, in a xenograft model, anti-CD3/4-1BBL expanded T cells controlled primary growth and prevented metastasis of autologous tumors while nonactivated and anti-CD3/anti-CD28 activated CD8+ cells did not. These results question prevailing models of tumor induced tolerance accompanying progressive tumor growth; rather, we show coexistence of progressive tumor growth and anti-tumor immunity, with costimulation provided by the tumor itself. They further demonstrate a potential new therapeutic role for 4-1BBL mediated costimulation in expanding tumor reactive CTLs for use in the adoptive immunotherapy of cancer.

Beta-platelet-derived growth factor receptor mediates motility and growth of Ewing's sarcoma cells

The Ewing's sarcoma family of tumors (ESFT) contain a translocation, t(11;22), which results in the novel oncogenic fusion protein EWS/FLI1. Platelet-derived growth factors (PDGF) and their receptors (PDGFR) are involved in the induction and proliferation of numerous solid tumors and are the potential candidates for novel targeted antitumor therapy. Since a relation was reported between PDGF-C and EWS/FLI1, we sought to characterize the PDGF signaling pathway in ESFT. Eight out of nine ESFT cell lines were found to express significant levels of beta-PDGFR. Interestingly, none of the tested cell lines expressed alpha-PDGFR, which is the receptor isotype required for PDGF-C binding. By immunohistochemical staining 47 of 52 (90.4%) archival tumor samples from patients with ESFT were positive for beta-PDGFR. ESFT cell lines were treated with PDGF-AA or PDGF-BB ligands to evaluate downstream signaling. Autophosphorylation of beta-PDGFR and tyrosine phosphorylation of PLC-gamma, PI3Kp85 and Shc were detected only in PDGF-BB-stimulated cells that express beta-PDGFR. Receptor function was further evaluated using chemotaxis assays that showed TC-32 cell migration towards PDGF-BB. A specific PDGFR kinase inhibitor AG1295 blocked beta-PDGFR activation, downstream signaling, growth in cell culture and chemotaxis of TC-32 cells. AG1295 also delayed tumor formation and prolonged survival in an ESFT animal model. We conclude that ESFT express beta-PDGFR and that this is a functional and potentially crucial signaling pathway. Therefore, beta-PDGFRs may provide a novel therapeutic target in ESFT that can be utilized to design better treatment modalities.

Induction of caspase 8 by interferon gamma renders some neuroblastoma (NB) cells sensitive to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) but reveals that a lack of membrane TR1/TR2 also contributes to TRAIL resistance in NB

The resistance of neuroblastoma (NB) cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis has been attributed to a lack of caspase 8 expression. Here we demonstrate a clinically applicable molecular targeting strategy that not only increases caspase 8 expression ex vivo in NB cell lines but also in the tumor tissues of NB patients receiving IFN-gamma treatment. We identify the functional caspase 8 promoter, which is different from the methylated region reported previously, and show promoter activity is up-regulated by IFN-gamma through a IFN-gamma activation site-containing region. IFN-gamma also induces TRAIL expression in NB cell lines. However, the IFN-gamma restoration of caspase 8 in some NB cells revealed persistent TRAIL resistance in most NB cell lines examined. This additional lesion in the TRAIL path is because of a loss of cell membrane TRAIL receptors (TR1/TR2) not only in cell lines but in most of the NB tumor tissues evaluated. Restoration of TR2 expression by transfection enhances IFN-gamma-induced TRAIL sensitivity. Furthermore, we have found that we can improve TRAIL sensitivity in NB by reconstituting caspase 8 with IFN-gamma and TR2 with chemotherapeutic agents.

Potential use of imatinib in Ewing's Sarcoma: evidence for in vitro and in vivo activity

BACKGROUND

Ewing's sarcoma cells express c-kit, a receptor tyrosine kinase, and its ligand, stem cell factor (SCF), creating a potential autocrine loop that may promote tumor survival. We thus examined whether the specific tyrosine kinase inhibitor imatinib mesylate (hereafter imatinib; formerly STI571) could inhibit the proliferation of Ewing's sarcoma cells in vitro and in vivo.

METHODS

The effect of imatinib on c-kit expression and phosphorylation in Ewing's sarcoma cells was examined by immunoblotting. The effect of imatinib on cell growth and apoptosis was examined with an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay and with a morphologic test and Annexin V staining, respectively. The effect of imatinib oral therapy (every 12 hours for 5-7 days) on primary tumor growth was assessed in Ewing's sarcoma xenografts in SCID/bg mice (5 or 10 mice per group).

RESULTS

All Ewing's sarcoma cell lines tested were sensitive to imatinib-mediated apoptosis with a concentration inhibiting growth by 50% (IC50) of 10-12 micro M. Imatinib inhibited SCF-mediated c-kit phosphorylation (IC50 = 0.1-0.5 microM). In the xenograft model, imatinib treatment resulted in the regression or control of primary Ewing's sarcomas. After 6 days of treatment, the mean lower extremity volume including xenograft tumor was 3744 mm3 (95% confidence interval [CI] = 3050 to 4437 mm3), 1442 mm3 (95% CI = 931 to 1758 mm3), and 346 mm3 (95% CI = 131 to 622 mm3) in mice treated with carrier alone or with imatinib at 50 mg/kg or at 100 mg/kg, respectively.

CONCLUSIONS

Imatinib interferes with growth of all Ewing's sarcoma cell lines tested in vitro and in vivo. Targeted inhibition of tyrosine kinase-dependent autocrine loops, therefore, may be a viable therapeutic strategy for Ewing's sarcoma.

Autoantibodies inhibit interleukin-7-mediated proliferation and are associated with the age-dependent loss of pre-B cells in autoimmune New Zealand Black Mice

Surface IgM+B220+ B cell precursors can be categorized as either leukosialin (CD43/S7) negative (late stage pre-B cells) or positive (pro-B/early pre-B cells). In autoimmune New Zealand Black (NZB) mice, bone marrow small pre-B cells (IgM-CD43-B220+) and pro-B/early pre-B cells (IgM-CD43+B220+) declined significantly with age. In particular, subpopulations of pro-B/early pre-B cells expressing the heat stable antigen (HSA) were found in lower proportions with age. Significant decreases in interleukin-7 (IL-7) colony forming units (CFU) were also seen in NZB mice by 6 to 8 months of age and accompanied alterations in the numbers of pro-B and pre-B cells in bone marrow. Concomitant with reduced numbers of B lineage precursor cells and IL-7 CFU in vivo, NZB mice produced serum IgM antibodies that strongly inhibited IL-7 CFU responses in vitro. Two monoclonal IgM antibodies (5G9, 2F5) derived from LPS stimulated 10-month-old NZB splenocytes recognized pre-B cell surface antigens on both pre-B cell lines and on IL-7 stimulated bone marrow pro-B/pre-B cells. However, these monoclonal antibodies (MoAb) failed to significantly stain ex vivo bone marrow cells. The 5G9 and 2F5 MoAbs also partially inhibited IL-7 CFU in vitro. These results suggest that NZB bone marrow becomes increasingly deficient in B cell precursors and especially in IL-7 responsive pre-B cells with age. IgM serum antibodies and monoclonal IgM antibodies derived from older NZB mice inhibit pre-B cell growth to IL-7. The production of such autoantibodies may interfere with B cell development in aging NZB mice by preventing IL-7-mediated proliferation.

B220- bone marrow progenitor cells from New Zealand black autoimmune mice exhibit an age-associated decline in Pre-B and B-cell generation

New Zealand Black (NZB) autoimmune mice exhibit progressive, age-dependent reduction in bone marrow pre-B cells. To ascertain the capacity of NZB bone marrow B220- cells to generate pre-B cells in a supportive environment, B-lineage (B220+) cell-depleted and T-cell-depleted bone marrow cells from NZB mice at 1 to 3, 6, and 10 to 11 months of age were adoptively transferred into irradiated (200R) C.B17 severe combined immunodeficient (SCID) mice. Bone marrow pre-B cells (sIgM- CD43[S7]- B220+) were assessed 3 and 10 weeks posttransfer. Pre-B cells and B cells were reconstituted in SCID recipients of older NZB progenitor cells by 10 weeks posttransplant, in contrast to the very low numbers of pre-B cells present in the donor bone marrow. However, B220- bone marrow progenitor cells from greater than 10-month-old NZB donors were deficient in the reconstitution of both pre-B and B cells in SCID recipients at 3 weeks post-transfer. This reflected a slower kinetics of repopulation, because older NZB-->SCID recipients had numbers of both pre-B and B cells similar to recipients of young NZB progenitor cells by 10 weeks posttransplant. Adoptive transfer of equal mixtures of BALB/c and older NZB bone marrow B220- progenitor cells into irradiated C.B17 SCID recipients failed to demonstrate active suppression. These results suggest that, with age, NZB bone marrow has reduced numbers and/or function of early B220- B-lineage progenitors. Consistent with this hypothesis, B220- bone marrow cells from older NZB mice were deficient in progenitors capable of yielding interleukin-7 (IL-7) responsive pre-B cells in vitro on stimulation with the pre-B-cell potentiating factor, insulin-like growth factor 1 (IGF-1).

Case management: managing financial and clinical outcomes in ophthalmic nursing

Case management is emerging in nursing as an effective and cost efficient model of care delivery for patients with complex nursing, medical, and psychosocial needs. The term "case management" first appeared in the social welfare literature in the early seventies and then later appeared in nursing literature (ANA, 1988). Nursing's concept of case management has been defined and interpreted to fit various health care settings. The purpose of this paper is to address a case management model and demonstrate through a case study how the case management model benefits the patient, the health care team, and the health care agency.