Topotecan is active against Wilms' tumor: results of a multi-institutional phase II study

Pediatric regimens in the treatment of adult-onset, metastatic Wilms tumor: A case report

The optimal treatment of adult-onset Wilms tumors (WTs) in elderly patients is a debated area, as pediatric protocols are thought to carry unacceptable toxicity. We treated a 62-year-old female with good performance status and Stage IV (T1b N1 M1) favorable histology WT using pediatric adjuvant and salvage chemoradiation protocols. Though she experienced nodal relapse and both adjuvant and salvage treatment were discontinued early due to toxicity, she obtained excellent oncologic outcomes, having remained disease-free for 32 months. We recommend considering pediatric protocols for elderly WT patients with good performance status, anticipating dose reductions and possible early chemotherapy termination.

Advances in the clinical management of high-risk Wilms tumors

Outcomes are excellent for the majority of patients with Wilms tumors (WT). However, there remain WT subgroups for which the survival rate is approximately 50% or lower. Acknowledging that the composition of this high-risk group has changed over time reflecting improvements in therapy, we introduce the authors' view of the historical and current approach to the classification and treatment of high-risk WT. For this review, we consider high-risk WT to include patients with newly diagnosed metastatic blastemal-type or diffuse anaplastic histology, those who relapse after having been initially treated with three or more different chemotherapeutics, or those who relapse more than once. In certain low- or low middle-income settings, socio-economic factors expand the definition of what constitutes a high-risk WT. As conventional therapies are inadequate to cure the majority of high-risk WT patients, advancement of laboratory and early-phase clinical investigations to identify active agents is urgently needed.

Advances in the clinical management of high-risk Wilms tumors

Outcomes are excellent for the majority of patients with Wilms tumors (WT). However, there remain WT subgroups for which the survival rate is approximately 50% or lower. Acknowledging that the composition of this high-risk group has changed over time reflecting improvements in therapy, we introduce the authors' view of the historical and current approach to the classification and treatment of high-risk WT. For this review, we consider high-risk WT to include patients with newly diagnosed metastatic blastemal-type or diffuse anaplastic histology, those who relapse after having been initially treated with three or more different chemotherapeutics, or those who relapse more than once. In certain low- or low middle-income settings, socio-economic factors expand the definition of what constitutes a high-risk WT. As conventional therapies are inadequate to cure the majority of high-risk WT patients, advancement of laboratory and early-phase clinical investigations to identify active agents is urgently needed.

Unmet needs for relapsed or refractory Wilms tumour: Mapping the molecular features, exploring organoids and designing early phase trials - A collaborative SIOP-RTSG, COG and ITCC session at the first SIOPE meeting

Wilms tumour (WT) accounts for about 6% of all childhood cancers and overall survival of WT is about 90% in international protocols. However, for WT subgroups with much poorer prognoses, i.e. typically high-risk (unfavorable) histology and/or relapse, there is an unmet need to better understand the biology of WT and to translate biological findings into clinics through early phase clinical trials that evaluate innovative therapies. The main challenges are the small numbers of children suitable for early phase trials, the genetic heterogeneity of WT and the low number of somatic mutations that are currently considered 'druggable'. Accordingly, a joint meeting between clinical and biology experts from the international cooperative groups of the Renal Tumour Study Group of the International Society of Paediatric Oncology, the Renal Tumour Committee of the Children's Oncology Group and the European Innovative Therapies for Children with Cancer consortium and parents representatives was organised during the first SIOPE meeting in Prague, 2019. We reviewed WT molecular features, ongoing/planned early phase trials and explored available knowledge on organoid technology. The key messages were: (1) relapsed WT should undergo whenever possible thorough molecular characterization and be enrolled in protocols or trials with systematic data collecting and reporting; (2) WT displays few known 'actionable' targets and currently no novel agent has appeared promising; (3) we need to improve the enrolment rate of WT candidates in early phase trials especially for the relatively small subgroup of relapses with an adverse prognostic signature; (4) despite some agnostic early phase trials existing, development of WT-focused trials are warranted; (5) growing organoids with parallel testing of drug panels seems feasible and may direct individual treatment and encourage clinical researchers to incorporate the most promising agents into early phase trials.

Dosing Recommendations for Pediatric Patients With Renal Impairment

A treatment gap exists for pediatric patients with renal impairment. Alterations in renal clearance and metabolism of drugs render standard dosage regimens inappropriate and may lead to drug toxicity, but these studies are not routinely conducted during drug development. The objective of this study was to examine the clinical evidence behind current renal impairment dosage recommendations for pediatric patients in a standard pediatric dosing handbook. The sources of recommendations and comparisons included the pediatric dosing handbook (Lexicomp), the U.S. Food and Drug Administration-approved manufacturer's labels, and published studies in the literature. One hundred twenty-six drugs in Lexicomp had pediatric renal dosing recommendations. Only 14% (18 of 126) of Lexicomp pediatric renal dosing recommendations referenced a pediatric clinical study, and 15% of manufacturer's labels (19 of 126) described specific dosing regimens for renally impaired pediatric patients. Forty-two products had published information on pediatric renal dosing, but 19 (45%) were case studies. When pediatric clinical studies were not referenced in Lexicomp, the renal dosing recommendations followed the adult and pediatric dosing recommendations on the manufacturer's label. Clinical evidence in pediatric patients does not exist for most renal dosing recommendations in a widely used pediatric dosing handbook, and the adult renal dosing recommendations from the manufacturer's label are currently the primary source of pediatric renal dosing information.

Activity of Vincristine and Irinotecan in Diffuse Anaplastic Wilms Tumor and Therapy Outcomes of Stage II to IV Disease: Results of the Children's Oncology Group AREN0321 Study

PURPOSE

AREN0321 evaluated the activity of vincristine and irinotecan (VI) in patients with newly diagnosed diffuse anaplastic Wilms tumor (DAWT) and whether a regimen containing carboplatin (regimen UH1) in addition to regimen I agents used in the National Wilms Tumor Study 5 (NWTS-5; vincristine, doxorubicin, cyclophosphamide, and etoposide plus radiotherapy) would improve patient outcomes.

PATIENTS AND METHODS

Patients with stage II to IV DAWT without measurable disease received regimen UH1. Patients with stage IV measurable disease were eligible to receive VI (vincristine, 1.5 mg/m² per day intravenously on days 1 and 8; irinotecan, 20 mg/m² per day intravenously on days 1-5 and 8-12 of a 21-day cycle) in an upfront window; those with complete (CR) or partial response (PR) had VI incorporated into regimen UH1 (regimen UH2). The study was designed to detect improvement in outcomes of patients with stage II to IV DAWT compared with historical controls treated with regimen I.

RESULTS

Sixty-six eligible patients were enrolled. Of 14 patients with stage IV measurable disease who received VI, 11 (79%) achieved CR (n = 1) or PR (n = 10) after 2 cycles. Doses of doxorubicin, cyclophosphamide, and etoposide were reduced midstudy because of nonhematologic toxicity. Four patients (6%) died as a result of toxicity. Four-year event-free survival, relapse-free survival, and overall survival rates were 67.7% (95% CI, 55.9% to 79.4%), 72.9% (95% CI, 61.5% to 84.4%), and 73.7% (95% CI, 62.7% to 84.8%), respectively, compared with 57.5% (95% CI, 47.6% to 67.4%; P = .26), 57.5% (95% CI, 47.6% to 67.4%; P = .048), and 59.2% (95% CI, 49.4% to 69.0%; P = .08), respectively, in NWTS-5.

CONCLUSION

VI produced a high response rate in patients with metastatic DAWT. AREN0321 treatment seemed to improve outcomes for patients with stage II to IV DAWT compared with NWTS-5, but with increased toxicity. The UH2 regimen warrants further investigation with modifications to reduce toxicity.

Prospective use of the single-mouse experimental design for the evaluation of PLX038A

PURPOSE

Defining robust criteria for drug activity in preclinical studies allows for fewer animals per treatment group, and potentially allows for inclusion of additional cancer models that more accurately represent genetic diversity and, potentially, allows for tumor sensitivity biomarker identification.

METHODS

Using a single-mouse design, 32 pediatric xenograft tumor models representing diverse pediatric cancer types [Ewing sarcoma (9), brain (4), rhabdomyosarcoma (10), Wilms tumor (4), and non-CNS rhabdoid tumors (5)] were evaluated for response to a single administration of pegylated-SN38 (PLX038A), a controlled-release PEGylated formulation of SN-38. Endpoints measured were percent tumor regression, and event-free survival (EFS). The correlation between response to PLX038A was compared to that for ten models treated with irinotecan (2.5 mg/kg × 5 days × 2 cycles), using a traditional design (10 mice/group). Correlations between tumor sensitivity, genetic mutations and gene expression were sought. Models showing no disease at week 20 were categorized as 'extreme responders' to PLX038A, whereas those with EFS less than 5 weeks were categorized as 'resistant'.

RESULTS

The activity of PLX038A was evaluable in 31/32 models. PLX038A induced > 50% volume regressions in 25 models (78%). Initial tumor volume regression correlated only modestly with EFS (r2 = 0.238), but sensitivity to PLX038A was better correlated with response to irinotecan when one tumor hypersensitive to PLX038A was omitted (r2 = 0.6844). Mutations in 53BP1 were observed in three of six sensitive tumor models compared to none in resistant models (n = 6).

CONCLUSIONS

This study demonstrates the feasibility of using a single-mouse design for assessing the antitumor activity of an agent, while encompassing greater genetic diversity representative of childhood cancers. PLX038A was highly active in most xenograft models, and tumor sensitivity to PLX038A was correlated with sensitivity to irinotecan, validating the single-mouse design in identifying agents with the same mechanism of action. Biomarkers that correlated with model sensitivity included wild-type TP53, or mutant TP53 but with a mutation in 53BP1, thus a defect in DNA damage response. These results support the value of the single-mouse experimental design.

Determining success rates of the current pharmacokinetically guided dosing approach of topotecan in pediatric oncology patients

BACKGROUND

Topotecan is a chemotherapeutic agent that is active against many pediatric tumors. Although its effect is related to systemic exposure, the interpatient variability in systemic clearance makes it challenging to achieve desired topotecan targets. This study aims to evaluate the success of the pharmacokinetically (PK) guided dosing process, which was used to achieve a target topotecan area under the concentration-time curve (AUC).

METHODS

Patients received an empiric topotecan dosage on the first day; the topotecan lactone AUC was determined, and based upon these values the topotecan dosage was adjusted. The success rates of both the empiric and PK-guided strategies were calculated. Patient-specific covariates were collected to explain variability observed in the empiric and PK-guided results. A simulation study was performed to assess the differences in cumulative topotecan dosage and systemic exposure between a PK-guided and standard dosing approach.

RESULTS

Data were collected from nine clinical trials open from 1996 to 2016 (n = 232 patients). The empiric dosing success rate was 35.5%, while the PK-guided rate was 64.4%. A difference in mean serum creatinine was observed between successful empiric studies and those above the AUC target. Compared to a standard dosing approach, the PK-guided group had a higher average cumulative dosage and systemic exposure.

CONCLUSION

The low empiric dosing success rate indicates that additional studies are needed to refine the initial topotecan dosage. The role of renal function, measured as serum creatinine, remains to be elucidated. However, the PK-guided targeting success rate highlighted the need to account for variable topotecan systemic clearance.

Pharmacotherapeutic Management of Wilms Tumor: An Update

Although differences exist in treatment and risk-stratification strategies for children with Wilms tumor (WT) between the European [International Society of Paediatric Oncology (SIOP)] and American [Children's Oncology Group (COG)] study groups, outcomes are very similar, with an overall survival of > 85%. Future strategies aim to de-intensify treatment and reduce toxicity for children with a low risk of relapse and intensify treatment for children with high-risk disease. For metastatic WT, response of lung nodules to chemotherapy is used as a marker to modify treatment intensity. For recurrent WT, a unified approach based on the use of agents that were not used for primary therapy is being introduced. Irinotecan is being explored as a new strategy in both metastatic and relapsed WT. Introduction of biology-driven approaches to risk stratification and new drug treatments has been slower in WT than in some other childhood cancers. While several new biological pathways have been identified recently in WT, their individual rarity has hampered their translation into clinical utility. Identification of robust prognostic factors requires extensive international collaborative studies because of the low proportion who relapse or die. Molecular profiling studies are in progress that should ultimately improve both risk classification and signposting to more targeted therapies for the small group for whom current therapies fail. Accrual of patients with WT to early-phase trials has been low, and the efficacy of these new agents has so far been very disappointing. Better in vitro model systems to test mechanistic dependence are needed so available new agents can be more rationally prioritized for recruitment of children with WT to early-phase trials.

Position paper: Rationale for the treatment of children with CCSK in the UMBRELLA SIOP-RTSG 2016 protocol

The International Society of Paediatric Oncology-Renal Tumour Study Group (SIOP-RTSG) has developed a new protocol for the diagnosis, treatment, and follow-up monitoring of childhood renal tumours - the UMBRELLA SIOP-RTSG 2016 protocol (the UMBRELLA protocol). This protocol has been designed to continue international collaboration in the treatment of childhood renal tumours and will be implemented in over 50 different countries. Clear cell sarcoma of the kidney, which is a rare paediatric renal tumour that most commonly occurs in children between 2 and 4 years of age, is specifically addressed in the UMBRELLA protocol.

Irinotecan for relapsed Wilms tumor in pediatric patients: SIOP experience and review of the literature-A report from the SIOP Renal Tumor Study Group

While irinotecan has been studied in various pediatric solid tumors, its potential role in Wilms tumor (WT) is less clear. We evaluated response and outcome of irinotecan-containing regimens in relapsed WT and compared our results to the available literature. Among 14 evaluable patients, one complete response (CR) and two partial responses (PRs) were observed in patients with initial intermediate-risk (CR and PR) and blastemal-type histologies (PR). Two patients were alive at last follow-up showing no evidence of disease. Our results and the reviewed literature suggest some effectiveness of irinotecan in the setting of relapsed WT.

Position paper: Rationale for the treatment of Wilms tumour in the UMBRELLA SIOP-RTSG 2016 protocol

The Renal Tumour Study Group of the International Society of Paediatric Oncology (SIOP-RTSG) has developed a new protocol for the diagnosis and treatment of childhood renal tumours, the UMBRELLA SIOP-RTSG 2016 (the UMBRELLA protocol), to continue international collaboration in the treatment of childhood renal tumours. This protocol will support integrated biomarker and imaging research, focussing on assessing the independent prognostic value of genomic changes within the tumour and the volume of the blastemal component that survives preoperative chemotherapy. Treatment guidelines for Wilms tumours in the UMBRELLA protocol include recommendations for localized, metastatic, and bilateral disease, for all age groups, and for relapsed disease. These recommendations have been established by a multidisciplinary panel of leading experts on renal tumours within the SIOP-RTSG. The UMBRELLA protocol should promote international collaboration and research and serve as the SIOP-RTSG best available treatment standard.

Review of phase I and II trials for Wilms' tumour - Can we optimise the search for novel agents?

Survival rates for patients with Wilms' tumour (WT) approximate 90% with refined use of currently available interventions. However, a subgroup of patients, with initial high-risk histopathology or relapsing disease, have a poor prognosis, and it is a challenge to identify and prioritise the development of new innovative approaches for these subgroups. We conducted a systematic literature search for published phase I and II clinical trials that registered patients with WTs and characterised the early phase trial activity, quantified response rates and highlighted avenues for further development. We identified 63 trials (48 phase I, three phase I/II, and 12 phase II trials) enrolling 214 patients with WTs, alongside other malignancies. The number of annually recruited WTs did not change significantly and was less than 20% of the potential candidates. The vast majority of the trials were conducted in North America, and 56 different interventions were investigated, including conventional chemotherapy and biologically targeted therapies. Overall, 33 WTs revealed some degree of tumour control. Of these, five patients demonstrated complete remission (2%), 15 patients partial response (7%) and 13 patients stable disease (6%). None of the included novel biologically targeted therapies emerged as promising interventions, and only conventional chemotherapy was able to induce a complete and partial response. We conclude that early phase trial recruitment of WTs is below expected levels, and the clinical outcome of the included patients is dismal. Improvement of the availability and recruitment to early phase trials for WTs, especially in Europe, is needed.

Pediatric phase I trial of oral sorafenib and topotecan in refractory or recurrent pediatric solid malignancies

Targeted kinase inhibitors and camptothecins have shown preclinical and clinical activity in several cancers. This trial evaluated the maximum tolerated dose (MTD) and dose‐limiting toxicities of sorafenib and topotecan administered orally in pediatric patients with relapsed solid tumors. Sorafenib was administered twice daily and topotecan once daily on days 1–5 and 8–12 of each 28‐day course. The study utilized a standard 3 + 3 dose escalation design. Three dose levels (DL) were evaluated: (1) sorafenib 150 mg/m² and topotecan 1 mg/m²; (2) sorafenib 150 mg/m² and topotecan 1.4 mg/m²; and (3) sorafenib 200 mg/m² and topotecan 1.4 mg/m². Pharmacokinetics were ascertained and treatment response assessed. Thirteen patients were enrolled. DL2 was the determined MTD. Grade 4 thrombocytopenia delaying therapy for >7 days was observed in one of six patients on DL2, and grade 4 neutropenia that delayed therapy in two of three patients on DL3. A patient with preexisting cardiac failure controlled with medication developed a transient drop in the left ventricular ejection fraction that improved when sorafenib was withheld. Sorafenib exposure with or without topotecan was comparable, and the concentration‐time profiles for topotecan alone and in combination with sorafenib were similar. One objective response was noted in a patient with fibromatosis. We determined MTD to be sorafenib 150 mg/m² twice daily orally on days 1–28 combined with topotecan 1.4 mg/m² once daily on days 1–5 and 8–12. While these doses are 1 DL below the MTD of the agents individually, pharmacokinetic studies suggested adequate drug exposure without drug interactions. The combination had limited activity in the population studied.

Renal tumor in developing countries: 142 cases from a single institution at Shanghai, China

BACKGROUND

The clinical management of children with renal tumors including Wilms' tumor, clear cell sarcoma, rhabdoid tumor and other renal tumors in our center was designed according to the National Wilms' Tumor Study Group protocols.

METHODS

A total of 142 consecutive patients who had been diagnosed as having renal tumors at Shanghai Children's Medical Center were reviewed retrospectively in the period of December 1998 and September 2012. Diagnosis and treatment were decided by a multidisciplinary team including oncologists, surgeons, pathologists and sub-specialized radiologists.

RESULTS

The median age of the patients at the time of diagnosis was 27 months. The tumor stages of the patients were as follows: stage I 24.6%, stage II 23.2%, stage III 32.3%, stage IV 14.1%, and stage V 5.6%. Favorable histology was diagnosed in 80.3%, anaplasia in 4.2%, clear cell sarcoma in 9.8%, rhabdoid tumor in 4.9%, and other renal tumors in 0.7% of the patients. The event-free and overall 5-year survival rates were 80% and 83%, respectively. Tumor relapse and progress was seen in 25 patients (17.6%). The median relapse time was 6 months (range: 2-37 months). Seven relapsing patients were retreated and four of them got second complete remission (three in stage II, one in stage I).

CONCLUSION

A multi-disciplinary team work model is feasible in developing countries, and the renal tumors protocols basically from developed countries are safe in developing countries.

Treatment of relapsed Wilms tumour (WT) patients: experience with topotecan. A report from the SIOP Renal Tumour Study Group (RTSG)

BACKGROUND

Topotecan has been variably incorporated in the treatment of patients with relapsed Wilms tumour (WT) who failed initial treatment with three or more effective drugs. Our objective was to describe outcome and to retrospectively investigate the potential role of topotecan in relapsed WT patients.

METHODS

Children who were treated with topotecan as part of their chemotherapeutic regimens for relapsed WT were identified and included in our retrospective study. Patient charts were reviewed for general patient characteristics, histology and stage at initial diagnosis, number and type of relapse, salvage treatment schedules, toxicity, response to treatment and outcome.

RESULTS

From 2000 to 2012, 30 children (median age at relapse 5.5 years, range 1.6-14.5 years) were identified to have received topotecan as part of their salvage regimens (primary progressive disease n = 3, first, second and third relapse n = 13, 9 and 2 respectively, partial response n = 3). Topotecan was administered as a single agent (12 patients) or in combination with other drugs (18 patients). Sixteen patients had high-risk histology according to the SIOP classification, 15 died within 12 months because of progressive disease. Fourteen patients had SIOP intermediate-risk histology of which four patients displayed objective responses to topotecan. Overall, 6 out of 14 intermediate-risk patients survived (median follow up of 6 years), however, three of whom (stage V) had bilateral nephrectomy after topotecan treatment.

CONCLUSIONS

Topotecan does not seem to show effectiveness in the treatment of relapsed WT patients with initial high-risk histology. In patients with intermediate-risk histology, the role of topotecan might deserve further attention, to prove its efficacy.

A novel trial of topotecan, ifosfamide, and carboplatin (TIC) in children with recurrent solid tumors

BACKGROUND

Ifosfamide, carboplatin, and etoposide (ICE) in children with refractory or recurrent solid tumors and lymphomas has resulted in good overall response rates (ORR). Etoposide, a topoisomerase-II inhibitor, however, has been associated with a significant increase in secondary leukemia. The rationale for substituting topotecan, a topoisomerase-I inhibitor, for etoposide in this regimen, a topoisomerase-II inhibitor, includes its limited toxicity profile and decreased leukemogenicity. Furthermore, topotecan in combination with both alkylators and platinating agents are additive and/or synergistic against a variety of solid tumors.

PROCEDURE

Patients with relapsed/refractory solid tumors received ifosfamide (9 g/m² ) and carboplatin (area under the curve: 3 mg/ml/min). Topotecan was also administered at 0.5 mg/m² /day × 3 days (N = 12) and in a small cohort (N = 3) at 0.75 mg/m² /day.

RESULTS

Fifteen patients were entered onto study. Two patients developed seizures/encephalitis secondary to ifosfamide. One patient had dose-limiting thrombocytopenia secondary to TIC that resolved with supportive care. Patients received a median of three cycles (1-3) of TIC. Of the 14 evaluable patients for response, 4/14 had a complete response (CR), 2/14 had a partial response (PR), and 1/14 patients had stable disease (SD). The ORR (CR + PR) was 43%.

CONCLUSION

TIC chemotherapy is feasible and tolerable in children and adolescents with refractory/recurrent solid tumors and lymphomas and results in a 43% excellent ORR in this poor-risk group of patients. A larger cohort of patients, especially in Wilms tumor and central nervous system (CNS) tumors, should be studied in the future to attempt to confirm these preliminary findings. Pediatr Blood Cancer 2015;62:274-278. © 2014 Wiley Periodicals, Inc.

Treatment of multiply relapsed wilms tumor with vincristine, irinotecan, temozolomide and bevacizumab

As most active chemotherapy agents against Wilms tumor are incorporated into upfront therapy, particularly for those patients with high risk for recurrence, novel regimens are needed to treat children with relapsed Wilms tumor. We describe four consecutive patients with multiply relapsed Wilms tumor who were treated with a combination of vincristine, irinotecan, temozolomide, and bevacizumab. Two had a complete response, and two had a partial response to treatment. Hematological toxicity and diarrhea were the main side effects. This regimen has activity in patients with multiply relapsed Wilms tumor without excessive toxicity, and should be evaluated further in this setting.

Rapid screening of novel agents for combination therapy in sarcomas

For patients with sarcoma, metastatic disease remains very difficult to cure, and outcomes remain less than optimal. Treatment options have not largely changed, although some promising gains have been made with single agents in specific subtypes with the use of targeted agents. Here, we developed a system to investigate synergy of combinations of targeted and cytotoxic agents in a panel of sarcoma cell lines. Agents were investigated alone and in combination with varying dose ratios. Dose-response curves were analyzed for synergy using methods derived from Chou and Talalay (1984). A promising combination, dasatinib and triciribine, was explored in a murine model using the A673 cell line, and tumors were evaluated by MRI and histology for therapy effect. We found that histone deacetylase inhibitors were synergistic with etoposide, dasatinib, and Akt inhibitors across cell lines. Sorafenib and topotecan demonstrated a mixed response. Our systematic drug screening method allowed us to screen a large number of combinations of sarcoma agents. This method can be easily modified to accommodate other cell line models, and confirmatory assays, such as animal experiments, can provide excellent preclinical data to inform clinical trials for these rare malignancies.

Children's Oncology Group's 2013 blueprint for research: renal tumors

Renal malignancies are among the most prevalent pediatric cancers. The most common is favorable histology Wilms tumor (FHWT), which has 5-year overall survival exceeding 90%. Other pediatric renal malignancies, including anaplastic Wilms tumor, clear cell sarcoma, malignant rhabdoid tumor, and renal cell carcinoma, have less favorable outcomes. Recent clinical trials have identified gain of chromosome 1q as a prognostic marker for FHWT. Upcoming studies will evaluate therapy adjustments based on this and other novel biomarkers. For high-risk renal tumors, new treatment regimens will incorporate biological therapies. A research blueprint, viewed from the perspective of the Children's Oncology Group, is presented.

Favorable response of heavily treated Wilms' tumor to paclitaxel and carboplatin

BACKGROUND

Heavily treated Wilms' tumor responding to the combination of paclitaxel and carboplatin has not yet been reported.

CASE REPORT

A 17-year-old man presented with hematuria. He received a diagnosis of Wilms' tumor with multiple lung metastases and was treated with preoperative chemotherapy including vincristine, dactinomycin, and doxorubicin, a right nephrectomy, and adjuvant chemotherapy, followed by pulmonary metastasectomy. During the next 8 years, he suffered from 4 relapses and has been treated with multiple anticancer agents including high-dose chemotherapy with autologous peripheral blood stem cell transplantation. Finally, the disease progressed due to peritoneal and pleural metastases. With opioid administration for left shoulder pain due to pleural metastasis, he received combination chemotherapy with carboplatin (area under the curve = 4) and paclitaxel (175 mg/m(2)) on day 1. After 2 cycles, he achieved a partial response with mild toxicity. He received 7 cycles of the chemotherapy and the time to progression was 200 days.

CONCLUSION

In a refractory case after intensive treatments, we succeeded to control the disease for a while.

Dependence of Wilms tumor cells on signaling through insulin-like growth factor 1 in an orthotopic xenograft model targetable by specific receptor inhibition

We have previously demonstrated an increased DNA copy number and expression of IGF1R to be associated with poor outcome in Wilms tumors. We have now tested whether inhibiting this receptor may be a useful therapeutic strategy by using a panel of Wilms tumor cell lines. Both genetic and pharmacological targeting resulted in inhibition of downstream signaling through PI3 and MAP kinases, G(1) cell cycle arrest, and cell death, with drug efficacy dependent on the levels of phosphorylated IGF1R. These effects were further associated with specific gene expression signatures reflecting pathway inhibition, and conferred synergistic chemosensitisation to doxorubicin and topotecan. In the in vivo setting, s.c. xenografts of WiT49 cells resembled malignant rhabdoid tumors rather than Wilms tumors. Treatment with an IGF1R inhibitor (NVP-AEW541) showed no discernable antitumor activity and no downstream pathway inactivation. By contrast, Wilms tumor cells established orthotopically within the kidney were histologically accurate and exhibited significantly elevated insulin-like growth factor-mediated signaling, and growth was significantly reduced on treatment with NVP-AEW541 in parallel with signaling pathway ablation. As a result of the paracrine effects of enhanced IGF2 expression in Wilms tumor, this disease may be acutely dependent on signaling through the IGF1 receptor, and thus treatment strategies aimed at its inhibition may be useful in the clinic. Such efficacy may be missed if only standard ectopic models are considered as a result of an imperfect recapitulation of the specific tumor microenvironment.

A phase I/II study of CY and topotecan in patients with high-risk malignancies undergoing autologous hematopoietic cell transplantation: the St Jude long-term follow-up

Fifty-eight consecutive children with high-risk malignancies were treated with CY, and targeted topotecan followed by autologous hematopoietic cell transplantation (AHCT) in a phase I/II Institutional Review Board-approved study. Twelve participants enrolled in phase I; 5 received dose level 1 of topotecan 3 mg/m(2) per day, with subsequent doses targeted to total systemic exposure of 100±20 ng h/mL and CY 750 mg/m(2) per day. Seven participants received dose level 2. CY dose escalation to 1 g/m(2) per day was considered excessively toxic; one died from irreversible veno-occlusive disease and two experienced reversible hepatotoxicity. These adverse events halted further dose escalation. A total of 46 participants were enrolled in phase II; results are on the 51 participants who received therapy at dose level 1, the maximum tolerated dose. Diagnoses included neuroblastoma (26), sarcoma (9), lymphoma (8), brain tumors (5), Wilms (2) and retinoblastoma (1). Twenty participants (39.3%) were in CR1 at enrollment; median age was 5.1 years. Most common non-hematological grade III-IV toxicity was gastrointestinal (n=37). Neutrophil and platelet engraftment occurred at a median of 15 and 24 days, respectively. Twenty-six (51%) participants remain alive at a median of 6.4 years after AHCT. CY 3.75 g/m(2), and targeted topotecan followed by AHCT are feasible and produce acceptable toxicity in children with high-risk malignancies.

Double high-dose chemotherapy and stem cell transplantation in adult Wilms’ tumor

High-dose chemotherapy intensification and hematopoietic stem cell support remains a valuable treatment option for the rare patient with relapsed Wilms’ tumor. We report a 22-year-old adult male with an initially diagnosed stage II Wilms’ tumor, treated by nephrectomy followed by adjuvant chemotherapy. After 1 year, an intra-abdominal relapse was treated with salvage ifosfamide carboplatin etoposide chemotherapy followed by autologous hematopoietic stem cell mobilization. It was intended that he would receive two tandem cycles of high-dose chemotherapy; the first consisting of melphalan etoposide carboplatin; however, the patient did not return to receive the second cycle while in remission, but did return later with grossly relapsed disease. He was then treated with a novel preparative regimen incorporating high-dose topotecan (topotecan, melphalan and cyclophosphamide). This case confirms the feasibility of double high-dose chemotherapy with hematopoietic stem cell support in relapsed Wilms’ tumor. A detailed discussion with an extensive review of the literature, regarding studies evaluating the role and indications of high-dose chemotherapy in Wilms’ tumor is provided.

Phase I study of topotecan in combination with temozolomide (TOTEM) in relapsed or refractory paediatric solid tumours

PURPOSE

To evaluate maximum tolerated dose and recommended dose (RD) for phase II studies of topotecan (TPT) combined with temozolomide (TMZ) (TOTEM) in children and adolescents with relapsed or refractory solid malignancies.

PATIENTS AND METHODS

Multicentre, phase I study with a standard '3+3' design in five dose increments. Eligible patients: aged 6 months to 21 years, diagnosis of a solid malignancy failed at least 2 previous lines of therapy. TMZ was administered orally, starting at 100 mg/m(2)/d, and TPT intravenously over 30 min, starting at 0.75 mg/m(2)/d over 5 consecutive days every 28 d. A pharmacokinetics analysis was performed on Day 1 and Day 5 of cycle 1.

RESULTS

Between February and October 2007, 16 patients were treated. The median age was 8.5 years (range, 3-19 years). Dose-limiting toxicity (grade 4 neutropenia and/or thrombocytopenia lasting more than 7 d) during the first cycle occurred in 2 of 3 patients at level 3 (TMZ 150 mg/m(2)/d and TPT 1.0 mg/m(2)/d) and was always manageable. Confirmed complete and partial responses were observed in 4 patients (25%), three with metastatic neuroblastoma and one with high-grade glioma. Seven patients had a stable disease. Pharmacokinetic data show a wide inter-individual variability. No significant differences were observed between plasma TMZ and TPT concentrations on Day 1 and Day 5 indicating the absence of pharmacokinetic interaction between the drugs.

CONCLUSIONS

The RD for the combination is TMZ 150 mg/m(2)/d and TPT 0.75 mg/m(2)/d with dose-limiting haematological toxicity. The observed activity deserves further evaluation in paediatric malignancies.

Efficacy of high-dose chemotherapy and autologous stem cell transplant for recurrent Wilms' tumor: a meta-analysis

Long-term survival of relapsed Wilms' tumor patients is about 40% to 70%. Modern second-line treatment consists of either (a) salvage chemotherapy+/-radiation therapy (CT) or (b) chemotherapy followed by high-dose chemotherapy and autologous hematopoietic stem cell rescue (ASCR). Here, we conduct an individual patient data meta-analysis on 100 patients collected from 6 studies to determine characteristics that predict survival in relapsed patients who received ASCR therapy. We compare these results with survival data on 118 CT treated patients from 2 recently published studies. Four year overall survival among the combined ASCR treated patients was 54.1% (95% CI: 42.8-64.1%). The ASCR patients who only relapsed in the lungs had higher 4-years survival rates 77.7% (58.6% to 88.8%) than those who relapsed in other locations and/or suffered multiple relapses 41.6% (24.8% to 57.6%). Although lung-only relapse is considered a favorable prognostic factor, there was no clear advantage for the patients treated with salvage chemotherapy. Four-year survival rates among stage I-II patients were about 30% higher with CT than ASCR, but the 2 were comparable for stage III-IV patients. These findings suggest salvage chemotherapy is typically the better choice for relapsed Wilms' tumor patients, ASCR could be considered for stage III-IV patients with a lung-only relapse.

Initial testing of topotecan by the pediatric preclinical testing program

BACKGROUND

Topotecan is a small molecule DNA topoisomerase I poison, that has been successful in clinical trials against pediatric solid tumors and leukemias. Topotecan was evaluated against the Pediatric Preclinical Testing Program (PPTP) tumor panels as part of a validation process for these preclinical models.

PROCEDURES

In vivo three measures of antitumor activity were used: (1) an objective response measure modeled after the clinical setting; (2) a treated to control (T/C) tumor volume measure; and (3) a time to event (fourfold increase in tumor volume for solid tumor models, or > or =25% human CD45+ cells in the peripheral blood for acute lymphoblastic leukemia, ALL models) measure based on the median event-free survival (EFS) of treated and control animals for each xenograft.

RESULTS

Topotecan inhibited cell growth in vitro with IC(50) values between 0.71 and 489 nM. Topotecan significantly increased EFS in 32 of 37 (87%) solid tumor xenografts and in all 8 of the ALL xenografts. Seventy-five percent of solid tumors met EFS T/C activity criteria for intermediate (n = 17) or high activity (n = 7). Objective responses were noted in eight solid tumor xenografts (Wilms, rhabdomyosarcoma, Ewing sarcoma, neuroblastoma). Among the six neuroblastomas, three achieved a PR. For the ALL panel, two maintained CRs, three CRs, and two PRs were observed.

CONCLUSIONS

Topotecan demonstrated broad activity in vitro and in vivo against both the solid tumor and ALL panels, with significant tumor growth delay generated in all the panels. These results further demonstrate the validity of the PPTP panel for preclinical testing of new drugs.

FDG positron emission tomography/computed tomography studies of Wilms' tumor

PURPOSE

The purpose of this analysis was to evaluate the utility of FDG PET/CT scanning in patients with Wilms' tumors.

METHODS

A total of 58 scans were performed in 27 patients (14 male, 13 female; ages: 1.9-23 years, median: 7 years) with proven Wilms' tumor. Twenty-six patients (56 scans) were studied at the time of suspected relapse, progressive disease, persistent disease, or for monitoring of therapy.

RESULTS

In the 27 patients with Wilms' tumor, 34 scans showed areas of abnormal uptake consistent with metabolically active tumors. Of the patients, 8 (24 scans) had pulmonary metastases larger than 10 mm in diameter, 10 (12 scans) had hepatic metastases, 11 (11 scans) had regional nodal involvement, 3 (3 scans) had bone metastases, 1 (1 scan) had chest wall involvement, 2 (2 scans) had pancreatic metastasis, and 5 (5 scans) had abdominal and pelvic soft tissue involvement. Two of eight patients with lung metastases had variable uptakes. Lung lesions 10 mm or smaller were not consistently visualized on PET scans. One patient with a liver metastasis showed no uptake on PET scan after treatment (size decreased from 45 to 15 mm).

CONCLUSION

Most Wilms' tumors concentrate FDG. However, small pulmonary metastases may be better visualized with CT. FDG PET/CT appears useful for defining the extent of involvement and assessing the response to treatment.

Treatment of relapsed Wilms tumors: lessons learned

Treatment regimens for recurrent Wilms tumor (WT) are currently designed to include drugs that are not used during primary chemotherapy, using a risk-stratified approach. Therapy of recurrent disease depends on the nature of initial treatment, and of recognized prognostic indicators inherent in the primary tumor. Several highly effective chemotherapy regimens, including ifosfamide-carboplatin-etoposide, cyclophosphamide-etoposide and carboplatin-etoposide, are considered first treatment choice for recurrent disease. While intense-dose chemotherapy is uniformly accepted to treat high-risk recurrent WTs, the optimal therapy for standard-risk children has yet to be defined, owing to the small number of such patients and their relatively better prognosis compared with high-risk recurrences. Recurrent tumors among those defined as very-high risk are likely to develop chemoresistant disease, and novel therapeutic strategies will be necessary to cure these patients. Evidence on how to properly administer surgery and radiotherapy at relapse is more fragmentary. The authors have reviewed the available experiences concerning the treatment of recurrent WT, and have attempted to provide the most up-to-date recommendations regarding the optimal risk-based treatment for these patients.

Application of a highly specific and sensitive fluorescent HPLC method for topotecan lactone in whole blood

Individualization of topotecan dosing reduces inter-patient variability in topotecan exposure, presumably reducing toxicity and increasing efficacy. However, logistical limitations (e.g. requirement for plasma, intensive bedside plasma processing) have prevented widespread application of this approach to dosing topotecan. Thus, the objectives of the present study were to develop and validate an HPLC with fluorescence detection method to measure topotecan lactone in whole blood samples and to evaluate its application to individualizing topotecan dosing. Plasma samples (200 microL) were prepared using methanolic precipitation, a filtration step and then injection of 100 microL of the methanolic extract onto a Novapak C(18), 4 microm, 3.9 x 150 mm column with an isocratic mobile phase. Analytes were detected with a Shimadzu Fluorescence RF-10AXL detector with an excitation and emission wavelength of 370 and 520 nm, respectively. This method had a lower limit of quantification of 1 ng/mL (S/N >or= 5; RSD 4.9%) and was validated over a linear range of 1-100 ng/mL. Results from a 5-day validation study demonstrated good within-day and between-day precision and accuracy. Data are presented to demonstrate that the present method can be used with whole blood samples to individualize topotecan dosing in children with cancer.

Current and emerging chemotherapy treatment strategies for Wilms tumor in North America

Wilms tumor is the most common primary renal malignancy occurring in childhood. Approximately 500 children are diagnosed with Wilms tumor annually in the US alone, most of whom are aged <5 years. Several prognostic factors have been identified, including stage of disease, tumor histology, patient age, tumor weight, and tumor-specific loss of heterozygosity for chromosomes 1p and 16q. During the period from 1969 to 2002, the National Wilms Tumor Study Group coordinated five multicenter Wilms tumor studies. The overall survival rate for Wilms tumor has risen to >90% for patients with tumors of favorable histology. However, the treatment of patients with Wilms tumor with anaplastic histology remains challenging. The optimal treatment strategies for Wilms tumor in relapse will be studied via international collaboration in the near future. Goals of emerging studies include minimizing toxicity while maintaining the outstanding cure rates for patients with a good prognosis and, through advancing biologic understanding and developing novel therapeutic approaches, improving the prognosis for those patients in whom effective cure of their disease continues to elude physicians.

Treatment of high-risk relapsed Wilms tumor with dose-intensive chemotherapy, marrow-ablative chemotherapy, and autologous hematopoietic stem cell support: experience by the Italian Association of Pediatric Hematology and Oncology

BACKGROUND

We evaluated an intensified chemotherapy strategy in children with Wilms tumor who relapsed with high-risk features.

PROCEDURES

From January 2001 to June 2006, we treated 20 consecutive children with reinduction chemotherapy (using ifosfamide/carboplatin/etoposide in 15/20 cases), with (n = 15) or without (n = 5) subsequent high-dose chemotherapy and hematopoietic stem cell support, surgery where feasible, and radiation therapy. The median time to relapse was 10 months after nephrectomy. All but two children initially received doxorubicin as first-line therapy.

RESULTS

All patients were assessed for outcome: 13 are currently alive, 12 of them in remission a median 25 months since their relapse, one with progressing tumor. The treatment was unsuccessful in eight children: the disease progressed during reinduction in three, and relapsed in five. There was one toxic death. All transplanted patients engrafted to a neutrophil count >0.5 x 10(3)/microl after a median 11 days, and to an unsustained platelet count >25,000/microl after a median of 13 days. Three-year disease-free and overall survival rates were 56 +/- 12% and 55 +/- 13%, respectively. Neither recurrence within 12 months of nephrectomy nor extra-lung recurrence negatively affected outcome. A survival advantage was demonstrated in patients without disease evidence prior to transplant.

CONCLUSION

A disease-free survival rate nearing 50% is a realistic target in children with high-risk recurrent Wilms tumor. The benefit of autologous hematopoietic stem cell transplantation for consolidation deserves to be investigated in a randomized, controlled study.

Topotecan distribution in an anephric infant with therapy-resistant bilateral Wilms tumor with a novel germline WT1 gene mutation

The therapeutic strategy for bilateral Wilms tumor (WT) remains a challenge. Especially in cases with chemotherapy resistant disease, bilateral nephrectomy is sometimes inevitable. For optimal cure rates stage V WT patients benefit from adjuvant treatment; however, there are limited data available on chemotherapy pharmacokinetics in anephric children. In this report, we describe a 10-month old girl with bilateral Wilms tumor and a novel germline WT1 gene mutation. This patient hardly showed any response on preoperative chemotherapy, and ultimately, underwent sequential bilateral tumor-nephrectomy. Subsequently, during peritoneal dialysis, she received topotecan as adjuvant chemotherapy based on plasma levels, indicating that this is a reasonable option as adjuvant treatment in therapy-resistant Wilms tumor patients after bilateral nephrectomy. This case showed a novel germline WT1 gene mutation of which the correlation with resistant phenotype has to be confirmed in larger cohorts of WT patients.