Phase II testing of melphalan in children with newly diagnosed rhabdomyosarcoma: a model for anticancer drug development

Rabdomiossarcoma: Avaliação do Protocolo IRS III utilizado no Hospital do Câncer (INCA) Rio de Janeiro 1988-1993

Foram estudados 39 casos de pacientes menores de 21 anos portadores de rabdomiossarcoma matriculados no Hospital de Câncer no período entre 1988 a 1993. O estudo baseia-se no protocolo IRS III (Intergroup Rhabdomyosarcoma Study III) quanto aos regimes terapêuticos utilizados, a distribuição por sítios primários, histologia, grupos e estádios. As curvas de sobrevida foram determinadas para dois grupos e momentos distintos: O primeiro grupo incluiu todos os pacientes, o momento zero foi considerado como o do início do tratamento e o evento final, a data da última observação. Para o segundo grupo foi considerado como momento zero o término do tratamento para aqueles pacientes que se encontravam em remissão completa, e como evento final o momento da recidiva ou da última observação para aqueles que ainda permaneciam sem evidências de doença. Foi utilizado o Método de Kaplan-Meier.

Developing New Agents for Treatment of Childhood Cancer: Challenges and Opportunities for Preclinical Testing

Developing new therapeutics for the treatment of childhood cancer has challenges not usually associated with adult malignancies. Firstly, childhood cancer is rare, with approximately 12,500 new diagnoses annually in the U.S. in children 18 years or younger. With current multimodality treatments, the 5-year event-free survival exceeds 80%, and 70% of patients achieve long-term “cure”, hence the overall number of patients eligible for experimental drugs is small. Childhood cancer comprises many disease entities, the most frequent being acute lymphoblastic leukemias (25% of cancers) and brain tumors (21%), and each of these comprises multiple molecular subtypes. Hence, the numbers of diagnoses even for the more frequently occurring cancers of childhood are small, and undertaking clinical trials remains a significant challenge. Consequently, development of preclinical models that accurately represent each molecular entity can be valuable in identifying those agents or combinations that warrant clinical evaluation. Further, new regulations under the Research to Accelerate Cures and Equity for Children Act (RACE For Children Act) will change the way in which drugs are developed. Here, we will consider some of the limitations of preclinical models and consider approaches that may improve their ability to translate therapy to clinical trial more accurately.

Discussion of Trial Designs for Biomarker Identification and Validation Through the Use of Case Studies

With the launch of the National Cancer Institute's Precision Medicine Initiative in 2015, there has been a shift to trial designs that tailor health care solutions to individual patients by using a screening platform and by moving away from the one-trial/one-biomarker-at-a-time approach. To make precision medicine a reality, it is critical to identify and validate potential biomarkers to help select patients who will truly benefit from a targeted therapy. In this article, we discuss five trial designs: enrichment, umbrella, basket, subgroup, and window of opportunity. For each trial design, we describe the design characteristics, use ongoing or completed trials as case studies, provide any recent advances to the trial design, and discuss advantages and disadvantages of each design.

Challenges and Opportunities for Childhood Cancer Drug Development

Cancer in children is rare with approximately 15,700 new cases diagnosed in the United States annually. Through use of multimodality therapy (surgery, radiation therapy, and aggressive chemotherapy), 70% of patients will be "cured" of their disease, and 5-year event-free survival exceeds 80%. However, for patients surviving their malignancy, therapy-related long-term adverse effects are severe, with an estimated 50% having chronic life-threatening toxicities related to therapy in their fourth or fifth decade of life. While overall intensive therapy with cytotoxic agents continues to reduce cancer-related mortality, new understanding of the molecular etiology of many childhood cancers offers an opportunity to redirect efforts to develop effective, less genotoxic therapeutic options, including agents that target oncogenic drivers directly, and the potential for use of agents that target the tumor microenvironment and immune-directed therapies. However, for many high-risk cancers, significant challenges remain.

The Evaluation of Animal Models in the Development of Anticancer Agents: From Preclinical to Clinical Tests

BACKGROUND

One of the main reasons for most of the anticancer drugs to fail in the late preclinical testing and early clinical trials is the differences in drug effects observed from animals and patients, and the challenge has been to find a balance to reduce the inherent differences from species.

OBJECTIVE

Predicting safe starting doses and dosing schedules for human clinical trials is the main purpose of toxicological studies of anticancer drugs.

METHODS

Relevant information and data were assimilated from manuscripts, congress publications, and online sources.

RESULTS

We systematically overview the cons and pros of animal models and briefed the ways to determine human clinical starting doses derived from animal toxicological studies for anticancer drugs.

CONCLUSION

This information helps smart select the suitable predictive model for anti-cancer drugs with the different mechanisms and emphasized the pharmaceutical challenges behind and ahead.

Patient-derived xenograft models in musculoskeletal malignancies

Successful oncological drug development for bone and soft tissue sarcoma is grossly stagnating. A major obstacle in this process is the lack of appropriate animal models recapitulating the complexity and heterogeneity of musculoskeletal malignancies, resulting in poor efficiency in translating the findings of basic research to clinical applications. In recent years, patient-derived xenograft (PDX) models generated by directly engrafting patient-derived tumor fragments into immunocompromised mice have recaptured the attention of many researchers due to their properties of retaining the principle histopathology, biological behaviors, and molecular and genetic characteristics of the original tumor, showing promising future in both basic and clinical studies of bone and soft tissue sarcoma. Despite several limitations including low take rate and long take time in PDX generation, deficient immune system and heterologous tumor microenvironment of the host, PDXs offer a more advantageous platform for preclinical drug screening, biomarker identification and clinical therapeutic decision guiding. Here, we provide a timely review of the establishment and applications of PDX models for musculoskeletal malignancies and discuss current challenges and future directions of this approach.

Quantum Mechanical Study of γ-Fe2O3 Nanoparticle as a Nanocarrier for Anticancer Drug Delivery

Using density functional theory (DFT), noncovalent interactions and four mechanisms of covalent functionalization of melphalan anticancer drug onto γ-Fe2O3 nanoparticles have been studied. Quantum molecular descriptors of noncovalent configurations were investigated. It was specified that binding of melphalan onto γ-Fe2O3 nanoparticles is thermodynamically suitable. Hardness and the gap of energy between LUMO and HOMO of melphalan are higher than the noncovalent configurations, showing the reactivity of drug increases in the presence of γ-Fe2O3 nanoparticles. Melphalan can bond to γ-Fe2O3 nanoparticles through NH2 (k 1 mechanism), OH (k 2 mechanism), C=O (k 3 mechanism) and Cl (k 4 mechanism) groups. The activation energies, the activation enthalpies and the activation Gibbs free energies of these reactions were calculated. Thermodynamic data indicate that k 3 mechanism is exothermic and spontaneous and can take place at room temperature. These results could be generalized to other similar drugs.

Preclinical Childhood Sarcoma Models: Drug Efficacy Biomarker Identification and Validation

Over the past 35 years, cure rates for pediatric cancers have increased dramatically. However, it is clear that further dose intensification using cytotoxic agents or radiation therapy is not possible without enhancing morbidity and long-term effects. Consequently, novel, less genotoxic, agents are being sought to complement existing treatments. Here, we discuss preclinical human tumor xenograft models of pediatric cancers that may be used practically to identify novel agents for soft tissue and bone sarcomas, and "omics" approaches to identifying biomarkers that may identify sensitive and resistant tumors to these agents.

Tumour volume reduction after neoadjuvant chemotherapy impacts outcome in localised embryonal rhabdomyosarcoma

BACKGROUND

Response (tumour volume reduction) to induction chemotherapy has been used to stratify secondary local and systemic treatment of Intergroup Rhabdomyosarcoma Study Group III (IRSG-III) embryonal rhabdomyosarcoma (RME) in consecutive CWS-trials. To evaluate its actual impact we studied response-related treatment and outcomes.

PROCEDURE

Patients with IRSG-III RME <21 years and non-response (NR, <33% volume reduction) in five consecutive CWS-trials were analysed and compared with partial responders (PAR, ≥ 33% reduction). The NR was reviewed and sub-classified as Objective Response (OR, <0%-33% reduction) or Stable/Progressive Disease (SPD).

RESULTS

Fifty-nine of 529 patients had NR (n = 34 OR, n = 25 SPD). Primary risk-factors including age, tumour size, and TN-classification did not differ between NR and PAR groups but NR had more patients with unfavourable sites comparatively (P = 0.04). There were no differences in primary risk-factors between OR and SPD. Significant factors associated with poor outcome in multivariate analysis were NR, TN-classification, age >10 years, tumour size >5 cm and therapy in older trials. After response assessment n = 24 NR continued to receive induction chemotherapy, n = 32 received other combinations and n = 3 no further chemotherapy. Forty-two non-responders were irradiated, and the tumours were completely resected in n = 20. After a median follow-up of 8 years, 34 NR are alive. Seventeen of 21 failures leading to disease-related deaths were locoregional. The five-year overall survival rate (OS) was 76 ± 4% for PAR, 79 ± 14% for OR, but only 40 ± 19% for SPD (P < 0.001).

CONCLUSION

Response to induction chemotherapy appears to be an important surrogate marker of poor outcome in patients with SPD largely due to ineffective local control.

Drug discovery in paediatric oncology: roadblocks to progress

Approval of new cancer drugs for paediatric patients generally occurs after their development and approval for treating adult cancers. As most drug development occurs in the industry setting, the relatively small market of paediatric oncology does not provide the financial incentives for companies to actively pursue paediatric oncology solutions. Indeed, between 1948 and January 2003 the FDA approved 120 new cancer drugs, of which only 30 have been used in children. This slow rate of development must be addressed in a meaningful way if we are to make progress in the most pressing settings in childhood cancer. In this Viewpoint article, the key opinion leaders in the field weigh in and offer practical advice on how to address this issue.

Non-invasive molecular imaging for preclinical cancer therapeutic development

Molecular and non-invasive imaging are rapidly emerging fields in preclinical cancer drug discovery. This is driven by the need to develop more efficacious and safer treatments, the advent of molecular-targeted therapeutics, and the requirements to reduce and refine current preclinical in vivo models. Such bioimaging strategies include MRI, PET, single positron emission computed tomography, ultrasound, and optical approaches such as bioluminescence and fluorescence imaging. These molecular imaging modalities have several advantages over traditional screening methods, not least the ability to quantitatively monitor pharmacodynamic changes at the cellular and molecular level in living animals non-invasively in real time. This review aims to provide an overview of non-invasive molecular imaging techniques, highlighting the strengths, limitations and versatility of these approaches in preclinical cancer drug discovery and development.

Initial testing of the hypoxia-activated prodrug PR-104 by the pediatric preclinical testing program

BACKGROUND

PR-104 is rapidly hydrolyzed to PR-104A in vivo, which is activated by reduction to the corresponding 5-hydroxylamine (PR-104H) and amine (PR-104M) to produce DNA interstrand cross-links. PR-104 activation can occur via hypoxia-dependent reductases and also independently of hypoxia by aldo-keto reductase (AKR) 1C3.

PROCEDURES

PR-104A was tested against the PPTP in vitro panel (10 nM to 100 µM), and PR-104 in vivo using a weekly × 6 schedule at its maximum tolerated dose (MTD) of 550 mg/kg. Subsequently PR-104 was tested at 270 and 110 mg/kg. Pharmacokinetics for PR-104 and its metabolites were determined, as were levels of AKR1C3 RNA and protein in xenografts.

RESULTS

In vitro, the leukemia models were most sensitive to PR-104A. In vivo, PR-104 induced objective responses at its MTD in 21/34 solid tumor models and maintained complete responses against 7/7 acute lymphoblastic leukemia (ALL) models. At 270 mg/kg and lower dose levels, PR-104 did not induce solid tumor regressions, suggesting a steep dose-response relationship. Pharmacokinetic analysis suggests higher systemic exposures to PR-104A and its metabolites in mice compared to those achievable in patients. Levels of AKR1C3 protein did not correlate with tumor responsiveness.

CONCLUSIONS

As monotherapy, PR-104 demonstrated a high level of activity against both solid tumor and ALL models at its MTD, but the activity was almost completely lost at half the MTD dose for solid tumors. Pharmacokinetic data at the PR-104 MTD from human trials suggest that PR-104 metabolites may not reach the plasma exposures in children that were associated with high-level preclinical activity.

Outcomes in paediatric metastatic rhabdomyosarcoma: results of The International Society of Paediatric Oncology (SIOP) study MMT-98

PURPOSE

Results are presented of the SIOP study MMT-98 for paediatric metastatic rhabdomyosarcoma (RMS), which evaluated intensive chemotherapy followed by low intensity 'maintenance' chemotherapy in standard risk patients (SRG). For poor risk patients (PRG), the value of a therapeutic window study, sequential high dose monotherapy to achieve a complete response (CR) followed by low dose maintenance chemotherapy was examined.

PATIENTS AND METHODS

From November 1998 to 2005, 146 patients aged 6 months to 18 years with metastatic RMS were entered. Forty-five were SRG, i.e. age<10 years and no bone marrow or bone involvement. Treatment was a 6-drug regimen with local therapy of surgery and/or radiotherapy followed by maintenance of 9 courses of vincristine, actinomycin D and cyclophosphamide (VAC). One hundred and one patients were PRG, i.e. >10 years, or with bone marrow or bone metastases. An upfront window study, high dose monotherapy, local treatment and then VAC maintenance therapy were given.

RESULTS

With a median follow-up of 1.52 years, the 3-year event-free survival (EFS) and overall survival (OS) for SRG were 54.92% and 62.14%, respectively, whilst for the PRG 16.17% and 23.17%. The corresponding adverse hazard ratio (HR) for the PRG was HR=2.65 (95% CI 1.63-4.31, p-value<0.001) for EFS and HR=2.51 (CI 1.53-4.11, p-value<0.001) for OS.

CONCLUSION

SRG patients' EFS and OS were comparable to those of previous studies. For PRG patients there was no improvement in survival.

The pediatric preclinical testing program: description of models and early testing results

BACKGROUND

The Pediatric Preclinical Testing Program (PPTP) is an initiative supported by the National Cancer Institute (NCI) to identify novel therapeutic agents that may have significant activity against childhood cancers. The PPTP has established panels of childhood cancer xenografts and cell lines to be used for in vivo and in vitro testing. These include panels for Wilms tumor, sarcomas (rhabdomyosarcoma, Ewing sarcoma, and osteosarcoma), neuroblastoma, brain tumors (glioblastoma, ependymoma, and medulloblastoma), rhabdoid tumors (CNS and renal), and acute lymphoblastic leukemia (ALL). Here, we describe the characteristics of the in vivo tumor panels and report results for the in vivo evaluation of two standard agents, vincristine and cyclophosphamide.

PROCEDURES

Solid tumors were grown subcutaneously in immune-deficient mice and tumor dimensions were measured weekly. ALL xenografts were inoculated intravenously and human CD45-positive cells were enumerated weekly.

RESULTS

Vincristine-induced objective responses in 6 of 24 (25%) and cyclophosphamide-induced objective responses in 18 of 28 (64%) solid tumor models. Comparable assessments of high levels of activity for these two agents were obtained using a tumor growth delay (TGD) measure. Both agents induced regressions in each of the ALL models evaluated.

CONCLUSIONS

We have established 51 solid tumor and 10 ALL in vivo models. The models identify vincristine and cyclophosphamide as having broad-spectrum activity. The PPTP tumor panels appear to generally recapitulate the activity of these agents against specific childhood cancers and to have the potential for identifying novel agents having significant clinical activity.

Pediatric oncology

Intensive use of cytotoxic agents in multimodality therapeutic regimens has resulted in almost 80% five-year disease-free survival and cure in the majority of childhood cancer patients. However, such success has come at the expense of severe acute or delayed toxicities and an increased occurrence of secondary cancers. With an increasing understanding of the genetic changes that underlie transformation in childhood cancer, rational approaches using agents that target these transforming events are being developed. Current and future strategies in developing tumor-selective therapy using inhibitors of signaling pathways dysregulated in leukemias (FLT3, NOTCH1) and solid/brain tumors (ErbB1-4, IGF-IR, PTCH1), and the challenges in developing less toxic, but equally effective treatments in pediatric oncology are presented.

Upfront window trial of topotecan in previously untreated children and adolescents with poor prognosis metastatic osteosarcoma: children's Cancer Group (CCG) 7943

BACKGROUND

Patients with metastatic osteosarcoma have a poor prognosis. The objectives of the study were to determine the antitumor activity and toxicity of topotecan (daily x5) in newly diagnosed patients with metastatic osteosarcoma followed by chemotherapy (ifosfamide, carboplatin, etoposide [ICE], alternating with cisplatin and doxorubicin [CD]).

METHODS

Newly diagnosed patients (< or =30 years of age) with extensive metastatic disease (primary and > or =5 pulmonary nodules and/or bone metastases) with normal hepatic, renal, and cardiac function were eligible. Patients were eligible to receive further topotecan after standard chemotherapy if they exhibited a response. Twenty-eight patients were enrolled. Seventeen had metastases to the lung only and 11 had metastases to the bone or multiple sites. Of 28 patients enrolled, 27 could be evaluated for response. A limited dose escalation was incorporated.

RESULTS

No responses were seen in the 11 patients treated at 3 mg/m(2)/day. One partial response (PR) and 1 clinical response (CLR) were reported among 15 patients who received topotecan at 3.5 mg/m(2)/day. No dose-limiting toxicity was observed. Principal nondose-limiting toxicities were hematologic and gastrointestinal. The 2- and 5-year event-free survival rates were low, 7% and 4%, respectively, but the 2- and 5-year overall survival rates were 44% and 22%, respectively.

CONCLUSIONS

Topotecan at dose of 3.5 mg/m(2)/day can be safely administered upfront to newly diagnosed patients without excessive toxicity. Insufficient activity was seen with topotecan in this schedule to warrant further studies in osteosarcoma. The combination of ICE and CD was tolerable when delivered after initial topotecan therapy.

Response to melphalan in up-front investigational window therapy for patients with metastatic Ewing's family tumours

The aim of the study was to determine the activity and toxicity of melphalan as a single agent given in up-front therapy for patients with newly-diagnosed Ewing's family tumours with bone/bone marrow metastases. Nineteen patients were enrolled from 2001 to 2004. The treatment consisted of up-front therapy with melphalan (two courses of 50 mg/m2, 3 weeks apart). The overall rate of response to melphalan (complete response+partial response, according to the RECIST criteria) was 78%. Transient grade 3-4 neutropenia, thrombocytopenia and anaemia were recorded in 97%, 81% and 28% of melphalan courses, respectively. No other relevant toxicities were recorded. Melphalan proved to be active in up-front treatment at non-myeloablative doses, and its toxicity was predictable and manageable. The schedule adopted did not interfere with any further intensive chemotherapy or myeloablative treatment in the majority of cases.

One- and two-stage designs for phase II window studies

The primary goal of phase II window studies in cancer is testing new single agents or combination therapies for newly diagnosed patients who are less likely to have multiple-drug-resistant tumours than the typical phase II patients who have failed one or more chemotherapeutic regimens. In addition, by utilizing newly diagnosed patients, one can assess the responsiveness in a population more representative of where the phase II agent might be applied in a true phase III setting. In general, the outcome of a patient on a phase II window study can be categorized as response, stable disease, or early disease progression. Phase II window studies sometimes require early stopping rules for both insufficient response rate and excessive early progression rates. In this paper, one-stage and two-stage designs for phase II window studies are developed, requiring the monitoring of two rates. It is shown that the power function is monotone in response rate and early disease progression rate. Consequently, the significance level and power are easy to compute. Computational procedures are described and examples are provided. The proposed method can be applied to other studies with categorical outcomes.

Pooled analysis of phase II window studies in children with contemporary high-risk metastatic rhabdomyosarcoma: a report from the Soft Tissue Sarcoma Committee of the Children's Oncology Group

PURPOSE

The Soft Tissue Sarcoma Committee of the Children's Oncology Group has conducted five upfront window trials in patients with newly diagnosed metastatic rhabdomyosarcoma to identify promising new treatment agents.

PATIENTS AND METHODS

This pooled analysis identified a total of 420 patients (115 from Intergroup Rhabdomyosarcoma Study III [IRS-III] and 305 from the five window trials). We assessed window therapy response rate, failure-free survival (FFS), and overall survival (OS).

RESULTS

Response rates (complete + partial response) assessed at week 6 of window therapy ranged from 41% to 55% and did not predict FFS (P = .073) or OS (P = .31). FFS was influenced by trial (P = .048); patients enrolled onto IRS-III and the ifosfamide/etoposide and ifosfamide/doxorubicin trials fared best. When grouped and compared with topoisomerase I poison trials, ifosfamide/topoisomerase II inhibitor trials had superior FFS (P = .013). However, there was no difference in survival.

CONCLUSION

Upfront phase II window trials can efficiently provide robust estimates of activity for new agents and combinations in newly diagnosed patients with high-risk rhabdomyosarcoma. Our data indicate that, for some phase II window trials, the risk of treatment failure may be increased but that the trend towards lower survival for some of the window trials compared with IRS-III is not statistically significant. Window nonresponders did not suffer worse FFS or OS than patients who responded to window therapy. Finally, these results provide a rationale for incorporating ifosfamide, etoposide, doxorubicin, and topoisomerase I poisons in future trials of high-risk metastatic rhabdomyosarcoma.

In vivo evaluation of ixabepilone (BMS247550), a novel epothilone B derivative, against pediatric cancer models

PURPOSE

Vinca alkaloids, agents that cause depolymerization of microtubules, are highly active in treatment of many pediatric cancers. In contrast, taxanes, agents that stabilize microtubules, are far less effective against the same cancer types. The purpose of the current study was to evaluate the antitumor activity of ixabepilone, an epothilone B derivative representing a new class of microtubule-stabilizing antimitotic agent in a wide variety of pediatric solid tumor models.

EXPERIMENTAL DESIGN

Ixabepilone was administered i.v. every 4 days for three doses to scid mice bearing s.c. human rhabdomyosarcoma (three lines), neuroblastoma (four), Wilms' tumors (six), osteosarcoma (four), or brain tumors (seven). Tumor diameters were measured weekly, and tumor growth or regressions were determined. Pharmacokinetic studies were done following a single administration of drug at the maximum tolerated dose (MTD) level (10 mg/kg).

RESULTS

At the MTD (10 mg/kg), ixabepilone induced objective responses (all tumors in a group achieved > or = 50% volume regression) in three of three rhabdomyosarcoma lines, three of five neuroblastomas, six of seven Wilms' tumor models, two of six osteosarcoma, and four of eight brain tumor models. However, the dose-response curve was steep with only 2 of 19 tumors models regressing (> or = 50%) at 4.4 mg/kg. In comparison, paclitaxel administered at the MTD on the same schedule failed to induce objective regressions of three tumor lines that were highly sensitive to treatment with ixabepilone. Pharmacokinetics following single i.v. administration of ixabepilone at its MTD (10 mg/kg) were biexponential with C(max) of 12.5 micromol/L, elimination half-life of 19.2 hours, and total area under the curve of 5.8 micromol/L-h. The achieved drug exposure of ixabepilone at this efficacious MTD dose level in mice is similar to those achieved in patients given the recommended phase II dose of 40 mg/m2 by either 1- or 3-hour infusion every 3 weeks, a regimen that has shown significant anticancer activity in phase II clinical trials in adult patients.

CONCLUSIONS

Administered at doses ranging from 66% to 100% of its MTD in mice, the epothilone B derivative ixabepilone shows broad spectrum activity against a panel of pediatric tumor xenograft models. Pharmacokinetic analysis indicates that the systemic ixabepilone exposure achieved in mice at its MTD is similar to that achieved in patients at the recommended phase II dose of 40 mg/m2 administered every 3 weeks. Importantly, the present results showed a clear distinction in sensitivity of pediatric solid tumors to this epothilone derivative compared with paclitaxel.

Current chemotherapeutic strategies for rhabdomyosarcoma

Rhabdomyosarcoma is a typical tumor of childhood and adolescence. Over the years there has been a gradual but important improvement in survival for patients with this tumor, despite its high grade of malignancy. These results are due to multidisciplinary treatment approaches including surgery, radiotherapy and especially chemotherapy. Rhabdomyosarcoma is a highly chemosensitive neoplasm, and the role of this therapeutic approach has also been clearly demonstrated in the adjuvant setting. This review covers current concepts on chemotherapy for rhabdomyosarcoma, with an overview of the results of the main clinical trials conducted over recent years and considerations of possible strategies for the near future. Recommendations for adult patients with rhabdomyosarcoma are also discussed, suggesting that these patients should be treated according to pediatric guidelines.

Childhood acute lymphoblastic leukaemia and relapse

Acute lymphoblastic leukaemia (ALL) is the most common childhood cancer. Treatment has improved but relapsed ALL remains more common than new cases of many 'common' paediatric malignancies. We have salvage regimens with substantial complete remission (CR) rates and increasing access to haematopoietic stem cell transplantation, but most patients who relapse die. We need better therapies. Insights into pharmacology may guide more effective use of existing agents. Novel agents with activity against resistant lymphoblasts offer an appealing strategy. However, most candidate agents fail, despite enthusiastic investigators, intriguing mechanisms of action and 'compelling' preclinical data. A number of existing combinations provide a 40% complete response rate in second or third relapse. Yet survival in third remission is <10%. Novel agents must, most likely, be integrated into multiagent combinations that provide a higher CR rate or better quality CR's than our conventional combinations in order to contribute substantially to cure. The march from bench to bedside requires careful consideration of the intermediate steps.

Rhabdomyosarcoma: new windows of opportunity

Rhabdomyosarcoma is a highly malignant, small blue cell tumor characterized by muscle differentiation. With modern treatment, more than 70% of children and adolescents with this disease are cured. Adequate biopsy to obtain sufficient tissue for accurate diagnosis and molecular characterization is critical. Patients must be assessed for tumor extent; the Intergroup Rhabdomyosarcoma Study (IRS) clinical group and Staging system is universally applied in North America. Multidisciplinary therapy is necessary to maximize cure rates. Local control relies on complete surgical excision when possible; those whose tumors are not completely excised and those with alveolar histology tumors require local irradiation to maximize local control. In North America, vincristine (Oncovin); Eli Lilly and Company, Indianapolis, http://www.lilly.com), dactinomycin (Cosmegen); Merck & Co., Inc., Whitehouse Station, NJ, http://www.merck.com), and cyclophosphamide are the standard chemotherapy agents. The IRS has used therapeutic window studies to confirm the predictive nature of preclinical xenograft models and to identify several new single agents and combinations of agents with activity in high-risk patient groups. Despite these efforts, the outcome for these high-risk patients remains poor. The next generation of Children's Oncology Group studies will evaluate the efficacy of topoisomerase-I inhibitors and dose-compression therapy approaches. New advances in molecular characterization of tumors, including gene-expression analysis, may identify new therapeutic targets that can be exploited by expanded preclinical drug discovery efforts, and hold the promise of revolutionizing risk-based therapies.

A phase II window trial of procarbazine and topotecan in children with high-grade glioma: a report from the children’s oncology group

The role of chemotherapy in the treatment of high-grade gliomas in children is unclear. Early reports were suggestive of improved outcome in children with high-grade glioma with the addition of chemotherapy after surgery and radiation therapy. Subsequent studies did not show similar favorable contribution of chemotherapy to the outcome of these children. Further efforts to identify active chemotherapy agents in children include use of agents that have shown efficacy in adult patients with high-grade glioma and agents that have shown promise in mice bearing human xenografts of brain tumors. A Pediatric Oncology Group (POG 9431) trial tested the activity of two such agents, procarbazine and topotecan in newly diagnosed patients with high-grade glioma who had measurable disease after diagnostic surgery. Neither agent showed efficacy within the confines of the statistical design of the study. This study showed that children with high-grade glioma have an innate resistance to alkylating agents based on mismatch repair deficiency and high levels of alkyguanine transferase (AGT). Future trials should consider strategies to overcome the resistance mechanisms in children with high-grade glioma.

Effectiveness of chemotherapy in rhabdomyosarcoma: example of orbital primary

The survival of patients with rhabdomyosarcoma has been progressively improved with successive protocols due to the development of multidisciplinary management and the data accumulated by international groups. Orbital rhabdomyosarcoma represents 10% of all cases and affects young children (median age: 6.8 years). It is a chemosensitive and radiosensitive tumour. Chemotherapy is designed to decrease the indications for local therapy (mainly radiotherapy) responsible for a high rate of sequelae (cosmetic, functional or secondary cancer). According to the International Society of Paediatric Oncology guidelines, local therapy is not indicated as first-line treatment in case of complete remission after chemotherapy. The 10-year survival of children with non-parameningeal orbital rhabdomyosarcoma is currently 87% and identical survivals are reported by the various collaborative groups despite the use of different treatments. Despite clinical trials demonstrating the efficacy of many types of chemotherapy (cisplatin, etoposide, doxorubicin, dacarbazine), the value of adding these drugs to combination chemotherapy comprising of an alkylating agent (cyclophosphamide or ifosfamide), vincristine and dactinomycin has not been formally demonstrated in terms of survival benefit for children with rhabdomyosarcoma. The authors review these various results and compare the current guidelines for the management of orbital rhabdomyosarcoma recommended by North American and European groups.

Integrating pharmacology and in vivo cancer models in preclinical and clinical drug development

Historically, cancer drug development has been a roller coaster. Numerous agents have shown exciting activity in preclinical models and yet have had minimal activity clinically. These disappointments have led to reasonable scepticism about the true value of both syngeneic and xenograft rodent tumour models in accurately identifying agents that will have important clinical utility. Whereas the development of newer techniques, including transgenic mouse models of cancer, offers the potential to develop more predictive models, the role of such mice in cancer drug development is not yet validated. To advance in our understanding of predictive model systems it may be wise to analyse both the successes and the failures of conventional models in order to understand some of their limitations and perhaps to avoid making the same mistakes in the future. Here we review the value and limitations of xenograft models, and the role of integrating preclinical pharmacology in developing new treatments for solid tumours of childhood.

Clinical and cellular pharmacology in relation to solid tumours of childhood

Our understanding of the clinical and cellular pharmacology of drugs commonly used in the treatment of childhood cancer have increased greatly over the past two decades. However, with the exception of childhood acute lymphoblastic leukaemia (ALL), our current knowledge of factors such as inter-patient pharmacokinetic variability and cellular determinants of chemosensitivity has not been utilized in the design of integrated clinical studies. Recent pre-clinical and clinical evaluation of the topoisomerase I inhibitors topotecan and irinotecan has highlighted the potential importance of pharmacological factors in their effectiveness as cytotoxics. In this review, the clinical and cellular pharmacology of vincristine, actinomycin D, doxorubicin, cyclophosphamide, ifosfamide, cisplatin, carboplatin and etoposide will be discussed in relation to the major paediatric solid tumours. For each disease type, knowledge of the clinical and cellular pharmacology of a candidate drug will be related to pharmacodynamic responses such as response, toxicity and prognosis. For diseases such as Wilms' tumour, osteogenic sarcoma and Ewing's tumour, histological response to initial induction chemotherapy is of prognostic significance, and the depth of response is increasingly recognised as an important determinant of prognosis for high-risk neuroblastoma. For several of these tumour types, the dose-intensity of chemotherapy may be an important variable in determining prognosis. However the relationship between pharmacokinetic variability, cellular pharmacology and the major determinants of chemosensitivity to those drugs employed in first line therapy is unknown. The study of these relationships, by means of up front window studies in children who present with high-risk disease, may be as important as the introduction of new agents. Indeed, the optimisation of current therapies may be required to allow a fully informed selection of those children for whom novel therapies are truly needed. Funding and international collaboration at the clinical and scientific level would be required to achieve these aims.

Activity of postoperative carboplatin, etoposide, and high-dose methotrexate in pediatric CNS embryonal tumors: results of a phase II study in newly diagnosed children

BACKGROUND

Chemotherapy is used as an alternative to irradiation or to minimize the irradiation exposure among infants with medulloblastoma or other CNS embryonal tumors. Adjuvant chemotherapy is commonly used in older children with high-risk medulloblastoma to improve survival or to allow a reduction in the craniospinal irradiation dose in standard-risk patients. However, optimal multimodality therapy, including the precise role of chemotherapy, has not been defined for these groups of patients. The objective of the present study is to assess the efficacy and toxicity of four postoperative courses of carboplatin, etoposide, and high-dose methotrexate in newly diagnosed children with medulloblastoma or other CNS embryonal tumors.

PROCEDURE

Twenty-eight children, aged from 0.3 to 15.9 years (median, 6.2 years) with post-operative measurable residual CNS embryonal tumors were enrolled, comprising medulloblastoma (n = 19), supratentorial PNET (n = 7), and pineoblastoma (n = 2). Post-operative chemotherapy comprised carboplatin 350 mg/m(2) and etoposide 100 mg/m(2) on Days 1 & 2, and methotrexate 8 g/m(2) on Day 3, repeated at 21-28-day intervals for a total of four courses. Therapy following completion of the initial Phase II study was influenced by patient age and investigator preference.

RESULTS

The combined complete response rate (CR, 7/19) and partial response rate (PR, 7/19) was 74% in patients with medulloblastoma, 89% for patients with PNET/pineoblastoma (CR, 2/9 and PR, 6/9), and for all patients it was 79%. Patients aged < 3 years at diagnosis had a combined PR and CR rate of 71% compared to 81% in patients aged > 3 years. Treatment was well tolerated although myelosuppression and thrombocytopenia were common.

CONCLUSIONS

The combination of carboplatin, etoposide, and high-dose methotrexate is highly active in pediatric patients with CNS embryonal tumors.

Vinorelbine in previously treated advanced childhood sarcomas: evidence of activity in rhabdomyosarcoma

BACKGROUND

Vinca alkaloids have proved active against a number of pediatric malignancies. The aim of this study was to assess the feasibility and effectiveness of using vinorelbine in previously treated pediatric patients with advanced sarcomas.

METHODS

From September 1998 to August 2001, 33 previously treated patients with progressive sarcoma were treated: 13 had rhabdomyosarcomas, 5 had other soft tissue sarcomas, 9 had Ewing sarcomas, and 6 had osteosarcomas. Vinorelbine was given intravenously on Days 1 and 8 of a 21-day treatment cycle. Four patients with uncontrolled pain or central nervous system invasion received concurrent radiotherapy and were only evaluated for toxicity.

RESULTS

One hundred seventy-eight treatment cycles were administered (median of four per patient, range 1-20). Grade 3 to 4 neutropenia occurred in 63% of patients, Grade 3 anemia in 9%, and Grade 3 thrombocytopenia in 3%. Nonhematological toxicity was mild or moderate, i.e., always lower than Grade 3, with the exception of one child who experienced paralytic ileus. Twenty-eight patients were assessable for response. Eight patients had a partial response, one patient had a minor response, and nine patients had stable disease. Objective responses were observed in 6 of 12 patients with rhadbomyosarcomas (five of six of the alveolar subtype), in one of five patients with osteosarcomas, and in one of seven patients with Ewing sarcomas. The median duration of response was 10 months (range, 3+ to 20).

CONCLUSIONS

Vinorelbine has a favorable toxicity profile with evidence of biological activity in already heavily treated pediatric patients with sarcomas. In particular, the objective response rate obtained for patients with alveolar rhabdomyosarcoma seems very promising. Due to the few cases considered here, further Phase II studies are needed to establish a potential role of vinorelbine in the treatment of these tumors.

High-dose chemotherapy in soft tissue sarcoma in children

Soft tissue sarcomas (STS) are highly malignant tumours that constitute 5-6% of all malignant childhood neoplasms. Of these, rhabdomyosarcoma (RMS) is the most common in children, and has a characteristic two-peak age incidence, 2-5 and 15-19 years. Most children with RMS are cured with conventional chemotherapy and local therapy (surgery with or without radiotherapy). Children with metastatic disease at presentation, particularly those older than 10 years or with bone marrow or bone involvement have a much poorer outcome. In this subgroup, high-dose therapy with stem cell rescue has been studied over the last two decades. Various single or multiagent chemotherapy regimens with or without radiotherapy and autologous stem cell rescue have been used as consolidation treatment with little success. Recent trials using sequential high-dose chemotherapy in the early phase of treatment have proved to be feasible, but the beneficial effect has to be confirmed. The role of purging remains unclear. Collaboration between different international groups is urgently required, in an attempt to improve the poor outcome of children with high risk STS.

Rhabdomyosarcoma and undifferentiated sarcoma in the first two decades of life: a selective review of intergroup rhabdomyosarcoma study group experience and rationale for Intergroup Rhabdomyosarcoma Study V

PURPOSE

To review the importance of prognostic factors in developing new protocols for children with rhabdomyosarcoma (RMS).

PATIENTS AND METHODS

Four studies conducted by the Intergroup Rhabdomyosarcoma Study (IRS) Group from 1972 through 1991.

RESULTS

Favorable prognostic factors are: (1) undetectable distant metastases at diagnosis; (2) primary sites in the orbit and nonparameningeal head/neck and genitourinary nonbladder/prostate regions; (3) grossly complete surgical removal of localized tumor at the time of diagnosis; (4) embryonal/botryoid histology; (5) tumor size < or = 5 cm; and (6) age younger than 10 years at diagnosis. The IRS-V protocols are risk-based and refine therapy by reducing exposure to cyclophosphamide and radiation therapy (XRT) in patients at low risk while adding new, active agents such as topotecan or irinotecan to the standard therapy of vincristine, actinomycin D, and cyclophosphamide (VAC) plus XRT for patients with unfavorable histology or advanced disease. Collection of biologic specimens from patients with newly diagnosed disease continues to identify other factors that may distinguish patients with favorable features from those who need more intensive therapy. A new protocol that takes into account their previous treatment is needed for patients with recurrent disease. This program (being planned) does not include bone marrow/stem cell reconstitution because this strategy has thus far failed to improve survival rates of patients with metastases at diagnosis.

CONCLUSION

Better understanding of biologic differences and new, active agents are needed to improve outcome of patients with unfavorable features at presentation.

Ifosfamide and etoposide are superior to vincristine and melphalan for pediatric metastatic rhabdomyosarcoma when administered with irradiation and combination chemotherapy: a report from the Intergroup Rhabdomyosarcoma Study Group

PURPOSE

This study was designed to estimate the partial and complete response rates (CR and PR) of two novel drug pairs (vincristine and melphalan vs. ifosfamide and etoposide) and to improve overall survival of previously untreated patients with metastatic rhabdomyosarcoma.

PATIENTS AND METHODS

One hundred twenty-eight patients were randomly assigned to phase II window therapy consisting of vincristine and melphalan (VM-containing regimen) or ifosfamide and etoposide (IE-containing regimen). Brief window therapy (12 wks) was immediately followed-up by vincristine, dactinomycin, and cyclophosphamide (VAC), chemotherapy, surgery, and irradiation, with continuation of either VM or IE in patients with initial response. Major endpoints were initial CR and PR rates after the phase II window phase of therapy, failure-free survival (FFS), and survival.

RESULTS

Patients who received the VM-containing regimen experienced significantly more anemia, neutropenia, thrombocytopenia, and had more cyclophosphamide dose reductions. The initial PR and CR rates were not significantly different for patients treated with either regimen (VM, 74%; IE, 79%; P = 0.428). However, FFS and overall survival (OS) at 3 years were significantly better with the IE-containing regimen (FFS: 33% vs. 19%; P = 0.043; OS: 55% vs. 27%; P = 0.012).

CONCLUSIONS

Although the VM-containing regimen produced a high response rate, inclusion of melphalan appeared to limit the cyclophosphamide dose that could be administered, and ultimately, this regimen was associated with a significantly worse outcome than was the IE-containing regimen. Also, the IE-containing regimen was associated with a gratifyingly high survival rate at 3 years (55%), which is significantly higher than has been observed on any previous Intergroup Rhabdomyosarcoma Study Group regimen for similar patients. We believe that this promising outcome indicates that this drug pair merits further randomized testing in metastatic rhabdomyosarcoma.

Carboplatin/ifosfamide window therapy for osteosarcoma: results of the St Jude Children's Research Hospital OS-91 trial

PURPOSE

To determine the activity of carboplatin/ifosfamide in patients with previously untreated osteosarcoma and to estimate patient outcomes after a multiagent chemotherapy protocol that eliminated cisplatin.

PATIENTS AND METHODS

Sixty-nine patients with newly diagnosed, previously untreated osteosarcoma received three cycles of carboplatin (560 mg/m(2) x 1) and ifosfamide (2.65 g/m(2)/d x 3). Assessment of response was evaluated after two (week 6) and three (week 9) chemotherapy cycles. At week 9, histologic response was assessed. Adjuvant therapy comprised two additional carboplatin/ifosfamide cycles, doxorubicin, and high-dose methotrexate. Patients were stratified at enrollment: stratum A, resectable primary tumor without metastases; stratum B, unresectable primary tumor; and stratum C, metastatic disease at diagnosis. Week 6 response was compared with that of a historic group that received only ifosfamide during the initial window evaluation.

RESULTS

The clinical and radiographic response rate to three cycles of carboplatin/ifosfamide was 67.7% (95% confidence interval, 55.0% to 78.8%). Compared with the historic population who received only ifosfamide, the combination of carboplatin and ifosfamide reduced the progressive disease rate at week 6 (31.9% v 9%, P: = .003). For patients in stratum A, the 3-year event-free survival and survival were 72.3% +/- 6.7% and 76.4% +/- 6.4%, respectively. Patients who received carboplatin-based therapy had less long-term renal toxicity and ototoxicity.

CONCLUSION

This pilot trial suggests that carboplatin/ifosfamide combination chemotherapy has substantial antitumor activity. In the context of a multiagent chemotherapy protocol comprising high-dose methotrexate and doxorubicin, we found that the addition of carboplatin/ifosfamide resulted in patient outcomes comparable to trials using cisplatin-based therapy with less long-term toxicity.

Up-front window trial of topotecan in previously untreated children and adolescents with metastatic rhabdomyosarcoma: an intergroup rhabdomyosarcoma study

PURPOSE

To investigate the antitumor activity and toxicity of topotecan, used alone and in combination with conventional therapy, in patients with metastatic rhabdomyosarcoma (RMS).

PATIENTS AND METHODS

Forty-eight patients younger than 21 years of age with newly diagnosed metastatic RMS received 2.0 to 2.4 mg/m(2) of topotecan intravenously daily for 5 days every 21 days before standard therapy. Two courses were given in the absence of progressive disease or excessive toxicity and response was assessed. Patients with at least a partial response (PR) to topotecan proceeded to therapy with alternating courses of vincristine 1.5 mg/m(2), dactinomycin 1.5 mg/m(2), and cyclophosphamide 2.2 g/m(2) (VAC) and vincristine 1.5 mg/m(2), topotecan 0.75 mg/m(2) daily x 5, and cyclophosphamide 250 mg/m(2) daily x 5. Patients who did not respond to topotecan received continuation therapy with VAC alone.

RESULTS

The overall response rate to topotecan was 46% (complete response, 4%; partial response 42%). Unexpectedly, patients with alveolar RMS had a higher rate of response (65%) than those with embryonal RMS (28%; P: = .08). The most common grade 3 or 4 toxicities were neutropenia (67%), anemia (33%), thrombocytopenia (25%), and infection (21%). Two-year failure-free survival and survival estimates were 24% and 46%, respectively. Response to window therapy did not correlate with survival.

CONCLUSION

The high response rate and acceptable toxicity profile of topotecan in children with advanced RMS support further evaluation of this agent in phase III trials. The superior responses in alveolar RMS are of interest.

Alveolar soft part sarcoma of the tongue

We report a case of alveolar soft part sarcoma--a rare malignancy that presented as a swelling at the base of the tongue in a 5-year-old child. Only about one-quarter of the few reported cases arise within the head and neck, the tongue and orbit being the favoured sites.

High-dose melphalan with autologous stem-cell rescue in metastatic rhabdomyosarcoma

PURPOSE

The European Collaborative MMT4-91 trial was conducted as a prospective nonrandomized study to evaluate the potential benefit of high-dose melphalan as consolidation of first complete remission in children with stage IV rhabdomyosarcoma.

PATIENTS AND METHODS

Fifty-two patients in complete remission after six courses of chemotherapy received "megatherapy": 42 received melphalan alone, whereas 10 received melphalan in combination with etoposide, carboplatin/etoposide, or thiotepa/busulfan and etoposide. The outcome of this group of patients was compared with that observed in 44 patients who were also in complete remission after six courses of identical chemotherapy (plus surgery or radiotherapy) but went on to receive a total of up to 12 courses of conventional chemotherapy (four cycles). No differences were found between the two groups regarding clinical characteristics, chemotherapy received before complete remission, or response to chemotherapy. In particular, there was no significant difference between the groups for site of primary tumor, histologic subtype, age at presentation, presence of bone or bone marrow metastases, or number of metastases.

RESULTS

The 3-year event-free survival (EFS) and overall survival (OS) rates were 29.7% and 40%, respectively, for those receiving high-dose melphalan or other multiagent high-dose regimens and 19.2% and 27.7%, respectively, for those receiving standard chemotherapy. The difference was not statistically significant (P =.3 and P =.2 for EFS and OS, respectively). There was a significant prolongation in the time from the last day of high-dose chemotherapy or the end of chemotherapy cycle 4 to the time of relapse in those receiving megatherapy (168 days for patients receiving megatherapy v 104 days for those receiving standard therapy; P =.05).

CONCLUSION

The addition of a high-dose alkylating agent to consolidation therapy may have prolonged progression-free survival in this poor-risk patient group, but it did not significantly improve the ultimate outcome.

Soft tissue sarcomas in children

In childhood, soft tissue sarcomas comprise a complex group of malignancies of varied histologic subtypes, the prognoses of which depend on the histology, age, site, extent of involvement and a variety of other factors. This paper discusses the varieties of tumors classified as soft tissue sarcomas in childhood and the multimodal approach taken to cure these tumors, with particular attention to the details of difficult surgical problems.