Angela Weirich

Twenty-four new cases of WT1 germline mutations and review of the literature: Genotype/phenotype correlations for Wilms tumor development

We report here 24 new Wilms tumor (WT) patients with germline WT1 alterations and a synopsis of our own previously described and literature cases in whom age of tumor‐onset, gender, and laterality were known. This combined database contains 282 patients, 117 patients with and 165 without WT1 germline alterations. Using this information we have determined the median age of tumor‐onset for patients with (12.5 months) and without WT1 gene alterations (36 months). The earliest onset was in patients with truncation (12 mo, 66 patients), followed by missense mutations (18 mo, 30 patients) and deletions (22 mo, 21 patients). Patients with the two most frequent nonsense mutations R362X and R390X and the Denys–Drash syndrome (DDS) hot spot mutation R394W/Q/L had a very early onset (9, 12, and 18 mo, respectively). The highest number of bilateral tumors was observed in the group of truncation mutations, with a higher percentage of bilateral tumors when truncations occurred in the 5′ half of the WT1 gene. In addition to genital tract anomalies (GU), early onset nephrotic syndrome with diffuse mesangial sclerosis and stromal‐predominant histology, tumor bilaterality, and early age of onset can now be added to the list of risk factors for carrying a germline WT1 mutation.

Allele loss in Wilms tumors of chromosome arms 11q, 16q, and 22q correlates with clinicopathological parameters

An extended analysis for loss of heterozygosity (LOH) on eight chromosomes was conducted in a series of 82 Wilms tumors. Observed rates of allele loss were: 9.5% (1p), 5% (4q), 6% (6p), 3% (7p), 9.8% (11q), 28% (11p15), 13.4% (16q), 8.8% (18p), and 13.8% (22q). Known regions of frequent allele loss on chromosome arms 1p, 11p15, and 16q were analyzed with a series of markers, but their size could not be narrowed down to smaller intervals, making any positional cloning effort difficult. In contrast to most previous studies, several tumors exhibited allele loss for multiple chromosomes, suggesting an important role for genome instability in a subset of tumors. Comparison with clinical data revealed a possible prognostic significance, especially for LOH on chromosome arms 11q and 22q with high frequencies of anaplastic tumors, tumor recurrence, and fatal outcome. Similarly, LOH 16q was associated with anaplastic and recurrent tumors. These markers may be helpful in the future for selecting high‐risk tumors for modified therapeutic regimens. Genes Chromosomes Cancer 22:287–294, 1998.

Complete necrosis induced by preoperative chemotherapy in Wilms tumor as an indicator of low risk: report of the international society of paediatric oncology (SIOP) nephroblastoma trial and study 9.

BACKGROUND The SIOP Nephroblastoma therapeutic protocols include a period of preoperative chemotherapy followed by nephrectomy and a period of postoperative chemotherapy. From the outset, identification of low-risk groups has been an aim of the SIOP Nephroblastoma Trials and Studies. Now that 90% of children with Wilms tumor can be cured, attention is even more focused on the identification of patients who could benefit from less aggressive postoperative therapy, thus minimizing the morbidity and late effects associated with treatment. The prognostic implications of total necrosis in nephroblastoma after chemotherapy have not been investigated hitherto. PROCEDURE Between November 1, 1987 and June 30, 1993, 599 patients referred to the SIOP-9 Nephroblastoma Trial and Study were preoperatively treated and classified as stages I-IV nonanaplastic Wilms tumor. RESULTS Of these 599 patients, pathologic examination of the nephrectomy specimen revealed a completely necrotic Wilms tumor (CNWT) with no viable tumor remaining in 59 (10%): these comprised 37 stages I-III and 22 stage IV. Of these patients, 58 (98%) had no evidence of disease at 5 years vs. 90% for the rest of the cohort (P < 0.05). Stages I-III patients represented 63% of CNWT and had a 97% overall survival rate. The only death was related to veno-occlusive disease and occurred in a stage I patient in the month following nephrectomy. Stage IV patients represented 37% of CNWT (vs. only 10% of all other cases of unilateral nonanaplastic Wilms tumor) and had a 100% rate of survival. Children with CNWT were older (mean 59 months vs. 43 months); their tumor at diagnosis was larger and had regressed more significantly at subsequent ultrasound examination. The data also uphold the hypothesis that Wilms tumors of blastemic pattern are most aggressive, but also are extremely responsive to chemotherapy. CONCLUSIONS Patients with unilateral nonanaplastic WT that showed total necrosis following preoperative chemotherapy had excellent outcome and should benefit from less aggressive postoperative treatment in further trials. Other very responsive tumors, such as Wilms with <10% viable tumor, should also be assessed.

Veno-occlusive disease of the liver in children treated for Wilms tumor.

INTRODUCTION Hepatotoxicity consistent with the clinical diagnosis of veno-occlusive disease (VOD) of the liver has been suspected after conventional anti-cancer chemotherapy in children. METHODS To establish the incidence of hepatotoxicity and its relationship with VOD, we analyzed toxicity data obtained on 511 children affected by Wilms tumor and treated according to the SIOP-9 protocol. They all received pre- and postnephrectomy chemotherapy using dactinomycin (AD) and vincristine (VCR) +/- other drugs +/- radiotherapy according to surgical stage and histology. RESULTS Sixty-four patients suffered at least one episode of hepatotoxicity and 41 satisfied the criteria for a clinical diagnosis of VOD. In this latter group, toxicity occurred during preoperative treatment in 15 patients and was confirmed histopathologically in 9 of the 16 liver biopsies obtained. There was a higher percentage of children aged less than 1 year at diagnosis in the VOD group than in the other patients (24% vs. 11.4%). The degree of liver damage in the younger patients seems important, as suggested by a higher increase in transaminases. VOD developed in 12% of the 68 irradiated children vs. 7% in the non-irradiated group. Statistical analysis showed an increased risk of VOD in younger patients (p < 0.001) and in those receiving radiotherapy (p < 0.001). All patients recovered after 6-180 days using supportive therapy only. CONCLUSIONS (1) 8% of children treated according to the SIOP-9 protocol, developed hepatotoxicity consistent with VOD. Excluding patients who received radiotherapy, the incidence was 6%. These figures are much higher than in earlier reports, though different diagnostic criteria were used. (2) Chemotherapy with AD and VCR seems to be a major cause of VOD. (3) Risk factors are young age and concomitant radiotherapy. (4) VOD does not prejudice positive outcome for these patients.

Evidence for susceptibility genes to familial Wilms tumour in addition to WT1, FWT1 and FWT2

Three loci have been implicated in familial Wilms tumour: WT1 located on chromosome 11p13, FWT1 on 17q12-q21, and FWT2 on 19q13. Two out of 19 Wilms tumour families evaluated showed strong evidence against linkage at all three loci. Both of these families contained at least three cases of Wilms tumour indicating that they were highly likely to be due to genetic susceptibility and therefore that one or more additional familial Wilms tumour susceptibility genes remain to be found.

Hepatotoxicity in patients treated according to the nephroblastoma trial and study SIOP-9/GPOH.

BACKGROUND A major problem for children receiving Wilms tumor (WT) chemotherapy is hepatotoxicity, which may even be life-threatening. Dactinomycin (AMD) has been shown to be an important factor, as has abdominal irradiation. PROCEDURE In the nephroblastoma trial and study SIOP-9 (SIOP-9) two different regimens for the application of AMD were used (standard dose over 3-5 days vs. double dose on a single day). In children at increased risk for local relapse, postoperative abdominal irradiation was given. We analyzed the influence of AMD and radiotherapy on the development of hepatotoxicity in 481 children treated in centers of the German Paediatric Oncology and Haematology Society (GPOH). A special questionaire was sent out for all patients with reduced treatment or delay of more than 1 week because of hepatotoxicity. Because SIOP and the National Wilms Tumor Study (NWTS) used different criteria to asses hepatotoxicity,we applied both definitions. RESULTS All 72 cases of mild or severe hepatotoxicity occurred during treatment with AMD over 3-5 days with the standard dose (9.4-22.5 microgram/kg/week) compared to none in the group receiving a double dose on 1 day (3.75-8 microgram/kg/week; P < 0.001). Irradiation of the right abdomen, including parts of the liver, enhanced liver toxicity significantly, with a relative risk (RR) of 2.6 (P < 0.003). Preoperative liver toxicity was more frequent in smaller children (P = 0.02) and especially if no dose reduction was done in children with body weight of less than 12 kg (RR 5.3, P = 0.01). If severe liver toxicity was defined according to NWTS criteria, 10% of all treated patients were affected compared to 4.8% if McDonalds criteria for hepatic veno-occlusive disease (VOD) were applied. CONCLUSIONS To diminish the hepatotoxicity of WT treatment, AMD dose intensity should be reduced (below 10 microgram/kg per week), especially in smaller children or when the liver is irradiated.

Clinical relevance of mutations in the Wilms tumor suppressor 1 gene WT1 and the cadherin‐associated protein β1 gene CTNNB1 for patients with Wilms tumors

Mutations in the Wilms tumor (WT) suppressor 1 gene (WT1) and the cadherin‐associated protein β1 gene (CTNNB1) are found predominantly in stromal type WT, defining a genetic subgroup. The clinical relevance of these mutations remains to be determined.

Abdominal Irradiation in Unilateral Nephroblastoma and its Impact on Local Control and Survival

PURPOSE The influence of abdominal radiotherapy was analyzed in 122 patients with unilateral Wilms tumor eligible for local irradiation according to postoperative SIOP-stage. MATERIAL & METHODS 122 of 454 children with Wilms tumor diagnosed between January 1989 and March 1994 in Germany were eligible for abdominal irradiation after preoperative chemotherapy and tumor resection according to SIOP9/GPOH protocol. There were 88 children with standard histology (SH; local Stage IIN+ and III) and 34 children with unfavorable histology (UH; anaplastic, clear cell and rhabdoid, local Stages II and III). Local irradiation was given postoperatively parallel to polychemotherapy according to protocol with appropriate dose reductions of Actinomycin D (dactinomycin) during the course of radiotherapy. Fifteen Gy to the tumor bed were prescribed in standard histology, with 30 Gy to regional lymph nodes, if histologically positive. Thirty Gy were given in unfavorable histology. Boost doses up to 15 Gy were possible for macroscopic residuals. Ages ranged between 6 months and 21 years (median 4.2 years). RESULTS Only 98 of 122 eligible children were irradiated. Reasons for ommission of radiotherapy were: Stage III only due to intraoperative biopsy (n = 6), due to resected cava thrombus (n = 5); young age (n = 2); undergrading/understaging (n = 7); other reasons (n = 4). There were 19 abdominal recurrences (4 of 88 with SH; 15 of 34 UH). In 5 patients, local recurrence was the only site of failure. There were 6 local failures in 24 nonirradiated but eligible children (25%) vs. 13 of 98 in irradiated children (13%); p = 0.15. In SH 0 of 15 nonirradiated vs. 4 of 73 treated children (p = NS) and in UH 6 of 8 nonirradiated vs. 9 of 26 irradiated children developed local recurrence (p < 0.05). Of 19 children with local recurrence as one site of failure, 18 have died. This comprises 67% of 27/122 children with fatal outcome in the observation period. In the patients eligible for abdominal radiotherapy, projected 3-year relapse-free survival is 85% for the group of children with standard histology and 41% for the children with unfavorable histology. CONCLUSION Despite impressive overall results for this multicenter trial in unilateral nephroblastoma, local recurrence remains a grave prognostic parameter. Evaluation of irradiated vs. eligible but not irradiated children suggests that radiotherapy to the tumor bed is of considerable impact for local control in the risk groups eligible for abdominal irradiation as defined in the SIOP9/GPOH protocol.