Phase II window studies: 10 years of experience and counting

Preoperative therapy with pazopanib in high-risk soft tissue sarcoma: a phase II window-of-opportunity study by the German Interdisciplinary Sarcoma Group (GISG-04/NOPASS)

INTRODUCTION

For resectable soft tissue sarcoma (STS), radical surgery, usually combined with radiotherapy, is the mainstay of treatment and the only potentially curative modality. Since surgery is often complicated by large tumour size and extensive tumour vasculature, preoperative treatment strategies with the aim of devitalising the tumour are being explored. One option is treatment with antiangiogenic drugs. The multikinase inhibitor pazopanib, which possesses pronounced antiangiogenic effects, has shown activity in metastatic and unresectable STS, but has so far not been tested in the preoperative setting.

METHODS AND ANALYSIS

This open-label, multicentre phase II window-of-opportunity trial assesses pazopanib as preoperative treatment of resectable STS. Participants receive a 21-day course of pazopanib 800 mg daily during wait time for surgery. Major eligibility criteria are resectable, high-risk adult STS of any location, or metachronous solitary STS metastasis for which resection is planned, and adequate organ function and performance status. The trial uses an exact single-stage design. The primary end point is metabolic response rate (MRR), that is, the proportion of patients with >50% reduction of the mean standardised uptake value (SUVmean) in post-treatment compared to pre-treatment fluorodeoxyglucose positron emission tomography CT. The MRR below which the treatment is considered ineffective is 0.2. The MRR above which the treatment warrants further exploration is 0.4. With a type I error of 5% and a power of 80%, the sample size is 35 evaluable patients, with 12 or more responders as threshold. Main secondary end points are histopathological and MRI response, resectability, toxicity, recurrence-free and overall survival. In a translational substudy, endothelial progenitor cells and vascular epithelial growth factor receptor are analysed as potential prognostic and predictive markers.

ETHICS AND DISSEMINATION

Approval by the ethics committee II, University of Heidelberg, Germany (2012-019F-MA), German Federal Institute for Drugs and Medical Devices (61-3910-4038155) and German Federal Institute for Radiation Protection (Z5-22463/2-2012-007).

TRIAL REGISTRATION NUMBER

NCT01543802, EudraCT: 2011-003745-18; Pre-results.

Emerging molecular-targeted therapies in early-phase clinical trials and preclinical models

Within the context of modern cooperative group trials, modification of standard cytotoxic chemotherapy has not improved survival in patients with rhabdomyosarcoma (RMS) over the last 30 years. There is need and interest to incorporate novel targeted anticancer agents into the treatment plans for children and adolescents with newly diagnosed RMS; however, targets directly driven by FOXO1 translocation remain elusive, and molecular events driving translocation negative tumors similarly remain ill-defined. Thus, alternate pathways driving the tumors require identification and targeting. Herein, we describe targeted therapies that could be of interest in RMS, but whose inclusion in clinical trials is thus far limited by scientific and regulatory criteria. Sorafenib, pazopanib, crizotinib, TH-302, aurora-kinase inhibitors, and anaplastic lymphoma kinase (ALK)/c-MET inhibitors will be discussed. The current preclinical and clinical data available, as well as limitations and challenges for each, will be outlined.

Selecting multimodal therapy for rhabdomyosarcoma

Rhabdomyosarcoma is a typical tumor of childhood, characterized by a high grade of malignancy, local invasiveness and a marked propensity to metastasize, but also a generally good response to chemotherapy and radiotherapy. Multimodal therapy is essential to cure rhabdomyosarcoma patients, but different uses of surgery, radiotherapy and chemotherapy, and their intensity, need to be selected and modulated to different patient risk groups. This article attempts to give an account of the current treatment options, the open and debated issues and the potential novel strategies for the near future.

Bone-marrow relapse in paediatric acute lymphoblastic leukaemia

Marrow relapse is the major obstacle to cure for 10-15% of young patients with acute lymphoblastic leukaemia (ALL). Recent investigations into the biology of minimal residual disease indicate that many early relapses derive from residual cells present at first diagnosis, but some late relapses might represent new mutations in leukaemic cells not eliminated by conventional therapy. Treatment of marrow relapse involves higher doses and more intensive schedules of the drugs used for initial therapy with or without haemopoietic stem cell transplantation. In most reports, transplantation is better than continuation chemotherapy in early marrow relapse, but its role in later relapse is less clear. Current therapy cures 10% of patients with early marrow relapses and 50% of those with late relapses, but outcomes have changed little in the past two decades. Understanding the molecular biology of ALL underlies development of improved risk stratification and new therapies. Although better drugs are needed, introduction of new agents into clinical trials in paediatric disease has been difficult. Innovative trial designs and use of valid surrogate endpoints may expedite this process.

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.

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.

Analysis of prognostic factors in patients with nonmetastatic rhabdomyosarcoma treated on intergroup rhabdomyosarcoma studies III and IV: the Children's Oncology Group

PURPOSE

The outcome for localized rhabdomyosarcoma (RMS) or undifferentiated sarcoma (UDS) is affected by age, histology, primary anatomic site, extent of disease, and therapy.

PATIENTS AND METHODS

We evaluated patient and disease characteristics for their ability to predict outcome for patients with nonmetastatic RMS or UDS treated on Intergroup Rhabdomyosarcoma Study (IRS) -III (1984 to 1991) or IRS-IV (1991 to 1997).

RESULTS

The estimated 5-year failure-free survival (FFS) rate was 90% for patients with embryonal RMS (ERMS) stage 1, group I or IIa; stage 2, group I; or group III orbit. The estimated 5-year FFS rate was 87% for patients with ERMS stage 1, group IIb or IIc; stage 1, group III nonorbit; stage 2, group II; and stage 3, group I or II; and 73% for patients with ERMS stage 2 or 3, group III. The estimated 5-year FFS rate was poor for patients with stage 2 or 3, group III ERMS with invasive (T2) tumors who were age younger than 1 year or 10 years or older (56%) and patients with stage 2 or 3, group III extremity primary tumors (43%). Overall, outcomes for patients with alveolar RMS (ARMS) or UDS were worse than for patients with ERMS. However, the 5-year FFS rate was good for patients with ARMS/UDS at favorable sites with group I or II (80%) or group III (76%) disease. The FFS rate was poorer for patients with ARMS/UDS at unfavorable sites with group I or II (66%) or group III (45%) disease. The estimated 5-year FFS rate was 31% for patients with group III ARMS/UDS at unfavorable sites with regional lymph node disease, which is similar to metastatic RMS.

CONCLUSION

Patient and disease characteristics identify distinct subsets with different outcomes, allowing the Soft Tissue Sarcoma Committee of the Children's Oncology Group to refine risk-adapted therapy assignment.

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.

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.

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.

Design Issues of Randomized Phase II Trials and a Proposal for Phase II Screening Trials

Future progress in improving cancer therapy can be expedited by better prioritization of new treatments for phase III evaluation. Historically, phase II trials have been key components in the prioritization process. There has been a long-standing interest in using phase II trials with randomization against a standard-treatment control arm or an additional experimental arm to provide greater assurance than afforded by comparison to historic controls that the new agent or regimen is promising and warrants further evaluation. Relevant trial designs that have been developed and utilized include phase II selection designs, randomized phase II designs that include a reference standard-treatment control arm, and phase II/III designs. We present our own explorations into the possibilities of developing “phase II screening trials,” in which preliminary and nondefinitive randomized comparisons of experimental regimens to standard treatments are made (preferably using an intermediate end point) by carefully adjusting the false-positive error rates (α or type I error) and false-negative error rates (β or type II error), so that the targeted treatment benefit may be appropriate while the sample size remains restricted. If the ability to conduct a definitive phase III trial can be protected, and if investigators feel that by judicious choice of false-positive probability and false-negative probability and magnitude of targeted treatment effect they can appropriately balance the conflicting demands of screening out useless regimens versus reliably detecting useful ones, the phase II screening trial design may be appropriate to apply.

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.