Beyond image defined risk factors (IDRFs): a delphi survey highlighting definition of the surgical complexity index (SCI) in neuroblastoma.

PURPOSE: Preoperative evaluation of Image Defined Risk Factors (IDRFs) in neuroblastoma (NB) is crucial for determining suitability for upfront resection or tumor biopsy. IDRFs do not all carry the same weighting in predicting tumor complexity and surgical risk. In this study we aimed to assess and categorize a surgical complexity (Surgical Complexity Index, SCI) in NB resection. METHODS: A panel of 15 surgeons was involved in an electronic Delphi consensus survey to identify and score a set of shared items predictive and/or indicative of surgical complexity, including the number of preoperative IDRFs. A shared agreement included the achievement of at least 75% consensus focused on a single or two close risk categories. RESULTS: After 3 Delphi rounds, agreement was established on 25/27 items (92.6%). A severity score was established for each item ranging from 0 to 3 with an overall SCI range varying from a minimum score of zero to a maximum score of 29 points for any given patient. CONCLUSIONS: A consensus on a SCI to stratify the risks related to neuroblastoma tumor resection was established by the panel experts. This index will now be deployed to critically assign a better severity score to IDRFs involved in NB surgery.

Biometric and morphological features on magnetic resonance imaging of fetal bladder in lower urinary tract obstruction: new perspectives for fetal cystoscopy.

OBJECTIVES: Incompatibility between currently available fetoscopes and the anatomical constraints of the distended fetal bladder, with the resulting curvature around the bladder neck, account for most technical difficulties during fetal cystoscopy in lower urinary tract obstruction (LUTO). The aim of this anatomical study was to assess by magnetic resonance imaging (MRI) the variation in three bladder angles (bladder-neck angle (BNA), vesicourethral angle (VUA) and angle between bladder dome and posterior urethra (DUA)), according to gestational age (GA), bladder volume and the presence of LUTO. METHODS: From our fetal medicine database, we retrieved for review 46 MRI examinations of male fetuses between 2015 and 2019, including 17 with LUTO, examined at a mean GA of 28.1 (range, 17.3-35.0) weeks and 29 age-matched controls, examined at 29.9 (range, 21.9-35.0) weeks. We measured bladder volume, bladder-wall thickness and the three bladder angles, and used the Mann-Whitney U-test to compare values between groups. Variations according to GA and bladder volume were determined using analysis of variance (ANOVA). A reliability study was performed using the Bland-Altman method and Lin's correlation coefficient was calculated. RESULTS: Both bladder volume and bladder-wall thickness were significantly greater in the LUTO group (P < 0.01). BNA was significantly larger in LUTO compared with control fetuses: the mean (range) was 127.1° (101.6-161.6°) vs 111.2° (88.5-157.3°) (P < 0.01). DUA averaged 117° and showed no difference between the groups (P = 0.92). No statistical comparison was performed on VUA since this was not measurable in most control fetuses. ANOVA showed no variation of any angle with bladder volume in both LUTO fetuses and control fetuses. BNA in LUTO fetuses was the only angle to vary with GA, being larger after, compared with at or before, 25 weeks (P = 0.04). The reliability study showed an acceptable bias for both intra- and interobserver reproducibility for all three angles. CONCLUSION: The findings that BNA is increased by approximately 15° in fetuses with LUTO and DUA averages 117° could aid in development of a customized fetal cystoscope and help to overcome the current technical challenges of fetal cystoscopy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Indications and results of diagnostic biopsy in pediatric renal tumors: A retrospective analysis of 317 patients with critical review of SIOP guidelines.

OBJECTIVES: According to the Renal Tumor Study Group (RTSG) of the International Society of Paediatric Oncology (SIOP), diagnostic biopsy of renal tumors prior to neoadjuvant chemotherapy is not mandatory unless the presentation is atypical for a Wilms tumor (WT). This study addresses the relevance of this strategy as well as the accuracy and safety of image-guided needle biopsy. METHODS: Clinical, radiological, and pathological data from 317 children (141 males/176 females, mean age: 4 years, range, 0-17.6) consecutively treated in one SIOP-affiliated institution were retrospectively analyzed. RESULTS: Presumptive chemotherapy for WT was decided for 182 patients (57% of the cohort), 24 (8%) were operated upfront, and 111 (35%) were biopsied at diagnosis. A non-WT was confirmed after surgery in 5/182 (3%), 11/24 (46%), and 28/111 (25%), respectively. Age at diagnosis was the most commonly (46%) used criterion to go for biopsy but a nine-year threshold should be retrospectively considered more relevant. Tumor volumes of clear cell sarcoma of the kidney and WT were significantly higher than those of other tumors (P = 0.002). The agreement between core-needle biopsy (CNB) and final histology was 99%. No significant morbidity was associated with CNB. CONCLUSION: The use of SIOP criteria to identify patients eligible for presumptive WT neoadjuvant chemotherapy or upfront surgery avoided biopsy in 65% of children and led to a 97% rate of appropriate preoperative chemotherapy. Image-guided CNB is a safe and accurate diagnostic procedure. The relevance of SIOP biopsy criteria might be improved by using an older age threshold (9 years instead of 6 years) and by adding initial tumor volume.

Towards the perfect ARM center: the European Union's criteria for centers of expertise and their implementation in the member states. A report from the ARM-Net.

BACKGROUND: Pediatric surgeons and patient organisations agree that fewer centers for anorectal malformations with larger patient numbers are essential to reach better treatment. The European Union transacts a political process which aims to realize such centers of expertise for a multitude of rare diseases. All the centers on a specific rare disease should constitute an ERN on that disease. ARM-Net members in different countries report on first experiences with the implementation of national directives, identifying opportunities and risks of this process. METHODS: Relevant details from the official European legislation were analyzed. A survey among the pediatric surgeons of the multidisciplinary ARM-Net consortium about national implementation was conducted. RESULTS: European legislation calls for multidisciplinary centers treating children with rare diseases, and proposes a multitude of quality criteria. The member states are called to allocate sufficient funding and to execute robust governance and oversight, applying clear methods for evaluation. Participation of the patient organisations is mandatory. The national implementations all over Europe differ a lot in respect of extent and timeframe. CONCLUSIONS: Establishing Centers of Expertise and a ERN for anorectal malformations offers great opportunities for patient care and research. Pediatric surgeons should be actively engaged in this process.

Surgical management of thymic epithelial tumors in children: lessons from the French Society of Pediatric Oncology and review of the literature.

PURPOSE: We report the results of a French multicenter retrospective study based on a period of more than 30 years and a review of the literature in order to more clearly define the surgical approach and specific pediatric risk factors. METHODS: Clinical data of children comprising all histologic subtypes of thymic epithelial tumors (TET) treated between 1979 and 2009 in French pediatric oncology centers were retrospectively analyzed and discussed in the light of a review of all pediatric cases reported in the literature. RESULTS: Nine cases were identified, corresponding to five females and four males with a median age of 13 years (range: 7.5-17). Histologic subtypes were type AB (n = 1), type B (n = 5) and type C (n = 3). Treatment consisted of tumor resection (4 R0, 4 R1, 1 R2) via right anterior thoracotomy, posterolateral thoracotomy, left thoracoscopy, sternotomy and cervicosternotomy, and/or chemotherapy, mainly cyclophosphamide-doxorubicin-cisplatin (CAP; n = 5), and/or radiotherapy (n = 4). Two patients with TET type C died. All other patients are alive with a median follow-up of 4 years (range: 1.5-20). Review of a total of 93 pediatric cases reported in the literature showed statistically significant associations between less favorable histologic subtypes and male gender (P = 0.012), advanced Masaoka stage (P < 0.001) and quality of resection (P < 0.001) respectively. CONCLUSIONS: A review of the literature and our series identified several risk factors to take into account in the therapeutically decision. Complete resection through a sternotomy is highly recommended.

Malformations, genetic abnormalities, and Wilms tumor.

BACKGROUND: Wilms Tumor (WT) can occur in association with tumor predisposition syndromes and/or with clinical malformations. These associations have not been fully characterized at a clinical and molecular genetic level. This study aims to describe clinical malformations, genetic abnormalities, and tumor predisposition syndromes in patients with WT and to propose guidelines regarding indications for clinical and molecular genetic explorations. PROCEDURE: This retrospective study analyzed clinical abnormalities and predisposition syndromes among 295 patients treated for WT between 1986 and 2009 in a single pediatric oncological center. RESULTS: Clinically identified malformations and predisposition syndromes were observed in 52/295 patients (17.6%). Genetically proven tumor predisposition syndromes (n = 14) frequently observed were syndromes associated with alterations of the chromosome WT1 region such as WAGR (n = 6) and Denys-Drash syndromes (n = 3), syndromes associated with alterations of the WT2 region (Beckwith-Wiedeman syndrome, n = 3), and Fanconi anemia (n = 2). Hemihypertrophy and genito-urinary malformations (n = 12 and n = 16, respectively) were the most frequently identified malformations. Other different syndromes or malformations (n = 10) were less frequent. Median age of WT diagnosis was significantly earlier for children with malformations than those without (27 months vs. 37 months, P = 0.0009). There was no significant difference in terms of 5-year EFS and OS between WT patients without or with malformations. CONCLUSIONS: The frequency of malformations observed in patients with WT underline the need of genetic counseling and molecular genetic explorations for a better follow-up of these patients, with a frequently good outcome. A decisional tree, based on clinical observations of patients with WT, is proposed to guide clinicians for further molecular genetic explorations.

The impact of anorectal malformations on anorectal function and social integration in adulthood: report from a national database.

AIM: The impact of anorectal malformation (ARM) on bowel function and social, educational and occupational end-points was investigated in adult patients entered on a national database. METHOD: Data from a national database of adult patients operated on between 1962 and 1999 for ARM were analysed. The database Malformations Ano-rectales et Pelviennes rares (MAREP) was part of a common information system, CEMARA, on rare congenital disorders. A self-administered questionnaire regarding bowel function, academic qualifications, employment and family status was mailed to patients. The type of ARM, subsequent follow-up and management including surgical interventions were retrospectively retrieved from medical records. RESULTS: Of 210 adult patients on the registry since 2008, 68 were included in this study. Only three (8.5%) had had regular follow-up. All reported some disturbance in bowel function. The fertility rate of 1.5 children per woman did not differ from the general population. CONCLUSION: Anorectal malformation ARM often leads to suboptimal bowel function in adulthood. This has an impact on social integration.

Germline mutations of the RET ligand GDNF are not sufficient to cause Hirschsprung disease.

Hirschsprung disease (HSCR, aganglionic megacolon) is a common congenital malformation leading to bowel obstruction, with an incidence of 1/5,000 live births. It is characterized by the absence of intrinsic ganglion cells in the myenteric and submucosal plexuses along variable lengths of the gastrointestinal tract. As enteric neurons are derived from the vagal neural crest, HSCR is regarded as a neurocristopathy. On the basis of a skewed sex-ratio (M/F = 4/1) and a risk to relatives much higher than the incidence in the general population, HSCR has long been regarded as a sex-modified multifactorial disorder. Accordingly, segregation analysis suggested an incompletely penetrant dominant inheritance in HSCR families with aganglionosis extending beyond the sigmoid colon. We and others have mapped a dominant gene for HSCR to chromosome 10q11.2 and have ascribed the disease to mutations in the RET proto-oncogene. However, the lack of genotype-phenotype correlation, the low penetrance and the sex-dependent effect of RET mutations supported the existence of one or more modifier gene(s) in familial HSCR. In addition, thus far, RET mutations only accounted for 50% and 15-20% of familial and sporadic HSCR patients, respectively. RET encodes a tyrosine kinase receptor whose ligand was unknown. Recently, the Glial cell line-derived neurotrophic factor (GDNF) has been identified to be a ligand for RET. Moreover, Gdnf-/- knockout mutant mice display congenital intestinal aganglionosis and renal agenesis, a phenotype very similar to the Ret-/- mouse. These data prompted us to hypothesize that mutations of the gene encoding GDNF could either cause or modulate the HSCR phenotype in some cases.

Induction of allograft tolerance by monoclonal CD3 antibodies: a matter of timing.

Despite remarkable progress in organ transplantation through the development of a wealth of immunosuppressive drugs highly effective at controlling acute rejection, two major problems still remain, the loss of transplants due to chronic rejection and the growing number of sensitized recipients due to previous transplants, transfusions or pregnancies. Induction of immune tolerance appears to be the only way to curb this complex situation. Here we describe that a therapy, already successfully used to restore immune tolerance to self-antigens in overt autoimmunity, is effective at promoting transplant tolerance. We demonstrate that a short low-dose course with CD3 antibodies started after transplantation, at the time of effector T cell priming to alloantigens, induces permanent acceptance of fully mismatched islet allografts. Mechanistic studies revealed that antigen-specific regulatory and effector T cells are differentially affected by the treatment. CD3 antibody treatment preferentially induces apoptosis of activated alloreactive T cells which is mandatory for tolerance induction. In contrast, regulatory T cells are relatively spared from CD3 antibody-induced depletion and can transfer antigen-specific tolerance thus arguing for their prominent role in sustaining long-term graft survival.

Peri-operative management of an adult with POLG-related mitochondrial disease.

POLG-related mitochondrial disease is a rare mitochondrial disorder that is potentially associated with anaesthetic complications such as propofol-related infusion syndrome. A 19-year-old man with mitochondrial DNA deletions and POLG-related disorders presented for an elective robotic Heller-Dor myotomy for the treatment of oesophageal pseudo-achalasia associated with severe gastro-oesophageal reflux. The fasting period was minimised to reduce the risk of metabolic stress. The anaesthetic technique included a rapid sequence induction with propofol and rocuronium, a remifentanil and sevoflurane-based general anaesthesia with multimodal monitoring and peri-operative lactate-free intravenous fluids with added dextrose. The patient did not experience propofol-related infusion syndrome but did have delayed tracheal extubation due to residual neuromuscular blockade requiring a second dose of sugammadex. This report demonstrates the safety of single-use, low-dose propofol in this patient group. Patients with POLG-related mitochondrial disease may be at risk of prolonged neuromuscular blockade, and appropriate dosing of neuromuscular blocking agents with monitoring of neuromuscular blockade is strongly encouraged.

Minimally invasive surgery for neuroblastic tumours: A SIOPEN multicentre study: Proposal for guidelines.

INTRODUCTION: Surgery plays a key role in the management of Neuroblastic tumours (NB), where the standard approach is open surgery, while minimally invasive surgery (MIS) may be considered an option in selected cases. The indication(s) and morbidity of MIS remain undetermined due to small number of reported studies. The aim of this study was to critically address the contemporary indications, morbidity and overall survival (OS) and propose guidelines exploring the utility of MIS for NB. MATERIALS & METHODS: A SIOPEN study where data of patients with NB who underwent MIS between 2005 and 2018, including demographics, tumour features, imaging, complications, follow up and survival, were extracted and then analysed. RESULTS: A total of 222 patients from 16 centres were identified. The majority were adrenal gland origin (54%) compared to abdominal non-adrenal and pelvic (16%) and thoracic (30%). Complete and near complete macroscopic resection (>95%) was achieved in 95%, with 10% of cases having conversion to open surgery. Complications were reported in 10% within 30 days of surgery. The presence of IDRF (30%) and/or tumour volume >75 ml were risk factors for conversion and complications in multivariate analysis. Overall mortality was 8.5%. CONCLUSIONS: MIS for NB showed that it is a secure approach allowing more than 95% resection. The presence of IDRFs was not an absolute contraindication for MIS. Conversion to open surgery and overall complication rates were low, however they become significant if tumour volume >75 mL. Based on these data, we propose new MIS guidelines for neuroblastic tumours.

Soft tissue sarcoma in children, adolescents and young adults: Outcomes according to compliance with international initial care guidelines.

BACKGROUND: Outcomes for adults with soft tissue sarcoma are better when managed at referral centers. Care guidelines advise for 5 main criteria: 1-Imaging before biopsy; 2-Tumor biopsy before surgery; 3-Multidiscipinary team discussion (MTD) before biopsy; 4-Biopsy in "expert centers"; 5-Somatic molecular biology feasible. The aim is to describe and assess the prognostic impact of initial management of STS according to the type of referring centers and the number of optimal criteria. METHODS: Monocentric retrospective analysis of the management of 127 youths (0-25 years) with localized STS treated from 2006 to 2015. RESULTS: Median age at diagnosis was 9.6 years (range: 025). Overall, only 41% patients had 5/5, 28% 3-4, 31% ≤2. No adequate imaging was performed before surgery/biopsy for 18% patients, no biopsy before treatment for 29%. Patients referred by "expert centers" had higher compliance to guidelines (P = 0.025). Upfront surgery was performed in 59/127 patients. Immediate re-operation was inversely related to the number of criteria (0% when 5 criteria vs. 14% for 3-4, 46% if ≤ 2; P < 0.001). For malignant tumors, outcome was better when 5 criteria were reached: 5 year EFS 90.8% (81.4-100.0%) vs. 71.6 for (60.4-84.9%; ≤4 criteria; p = 0.033), OS 93.6% (85.5-100%) vs. 79.5% (68.9-91.8%; p = 0.11), and LRFFS 90.6% (81.0-100.0) vs. 73.1% (62.0-86.3%; p = 0.047). CONCLUSION: Less than half of the youths with STS are initially managed according to international guidelines, highlighting the need for better information about optimal management. These results plead for immediate management in reference centers to reduce initial burden of therapy.

Management of Wilms tumors in Drash and Frasier syndromes.

BACKGROUND: Children with WT1 gene-related disorders such as Denys-Drash syndrome (DDS) and Frasier syndrome (FS) are at increased risk of Wilms tumor and end-stage renal disease. We investigated whether Wilms tumors in these patients displayed a specific phenotype or behavior and whether nephron-sparing surgery was beneficial. PROCEDURE: We retrospectively studied all patients with DDS, FS, or other WT1 mutations treated at our institutions between 1980 and 2007. RESULTS: We identified 20 patients, of whom 18 had benign or malignant tumors. Wilms tumors occurred in 15 patients, being unilateral in 10 and bilateral in 5 (20 tumors). Median age at Wilms tumor diagnosis was 9 months. No patients had metastases. According to the International Society of Pediatric Oncology Working Classification, there were 19 intermediate-risk tumors and one high-risk tumor; no tumor was anaplastic. In patients with nephropathy who underwent unilateral nephrectomy for Wilms tumor or nephron-sparing surgery for bilateral Wilms tumor, mean time to dialysis was 11 or 9 months, respectively. Other tumors included three gonadoblastomas (in two patients), one retroperitoneal soft-tissue tumor, and one transitional cell papilloma of the bladder. Two patients, both with stage I Wilms tumor, died from end-stage renal disease-related complications. The median follow-up time for the 18 survivors was 136 months (range, 17-224 months). CONCLUSION: Most Wilms tumors in children with WT1-related disorders were early-stage and intermediate-risk tumors, with a young age at diagnosis. In patients without end-stage renal disease, nephron-sparing surgery should be considered for delaying the onset of renal failure.

Preserving fertility in prepubertal children.

BACKGROUND: As a result of advances in treatment, almost 80% of children and adolescents who currently receive a diagnosis of cancer become long-term survivors. Potential adverse consequences of treatment include impaired puberty and fertility due to gonadal removal, genital tract injury or damage to germ cells from adjuvant therapy. In recent years, treatment of solid tumors and hematological malignancies has been modified in an attempt to minimize damage to the reproductive system. Simultaneously, advances in assisted reproductive technologies have led to new possibilities for the prevention and treatment of infertility. We review experimental data in animal models and clinical experience in adults and discuss strategies to preserve fertility in prepubertal children. CONCLUSIONS: Fertility preservation should now be considered in children facing cancer treatment that has a high risk of gonadal toxicity including high-dose chemotherapy and bilateral irradiation of the gonads at toxic doses.

Is laparoscopic management suitable for solid pseudo-papillary tumors of the pancreas?

PURPOSE: Solid pseudo-papillary tumors (SPT) are rare pancreatic neoplasms of low-malignant potential occurring mainly in young women. The purpose of this report is to describe our experience with laparoscopic management of these tumors with 4-year follow-up. METHODS: Three children with SPT were admitted to two hospitals in Paris, France, between February 2000 and December 2006. Diagnosis or treatment was carried out using laparoscopic techniques (biopsy and resection in one case and biopsy only in two). Long-term follow-up data were collected. RESULTS: All three patients presented recurrences within 3 years after resection, i.e., disseminated peritoneal recurrence in two patients and local recurrence in one. The two patients with peritoneal recurrences were treated by surgical resection and chemotherapy. The patient with local recurrence could not be treated due to contraindicating local factors. All three patients were alive at the time of this writing. CONCLUSION: This is the first report describing long-term follow-up after laparoscopic management of SPT. All three patients developed recurrences. These poor results contrast sharply with the low risk of local or disseminated recurrence after open laparotomy without chemotherapy that has been considered as the treatment of choice up to now. Recurrences after laparoscopic management may have been due to diffusion of tumor cells caused by gas insufflation especially during biopsy. Laparoscopic biopsy should not be performed in patients presenting SPT.

Transcription factors involved in pancreas development are expressed in paediatric solid pseudopapillary tumours.

AIMS: Solid pseudopapillary tumours (SPT) are rare pancreatic tumours, especially in children. The origin of this benign tumour remains unknown. Mutations of beta-catenin, a gene essential for pancreatic development, are constantly found, leading to delocalization of immunohistochemical signals from the cytoplasm to the nuclei of tumour cells. The aim was to report clinical and histological data of eight children with SPT and explore the immunohistochemical expression of pancreatic duodenal homeobox (PDX) 1 and Sox9, known to be crucial for pancreatic development and linked to the beta-catenin cascade. METHODS AND RESULTS: Eight children with features suggestive of SPT underwent surgical resection. Tumours displayed typical histological appearances. One was incompletely resected and recurred. Immunolabelling revealed nuclear location of beta-catenin in all cases and strong cytoplasmic but no nuclear expression of PDX1 or Sox9 in all but one case. CONCLUSIONS: The clinical behaviour of SPT in the paediatric population is similar to its adult counterpart. Complete surgical resection is essential. PDX1 and Sox9 proteins are exclusively expressed in the cytoplasmic compartment in SPT, suggesting overexpression of the corresponding genes linked to beta-catenin mutations. These findings favour the hypothesis that SPT originates from transformation of normally quiescent pancreatic stem cells.

Rhabdomyosarcoma an ubiquitous pediatric tumour.

Rhabdomyosarcoma is the most common soft tissue tumor in children. It occurs everywhere and its prognosis depends on the location and its histological type--embryonic or alveolar. The new immunohistochemical markers desmin and myogenin in combination with molecular biological detection of specific translocations in alveolar rhabdomyosarcoma improved diagnostic capacities. Less aggressive treatment in curable cases reduces the undesirable outcomes of therapy.

Abdominal desmoplastic small round cell tumor without extraperitoneal metastases: Is there a benefit for HIPEC after macroscopically complete cytoreductive surgery?

BACKGROUND: Desmoplastic Small Round Cell Tumor (DSRCT) is a rare disease affecting predominantly children and young adults and for which the benefit of hyperthermic intraperitoneal chemotherapy (HIPEC) after complete cytoreductive surgery (CCRS) remains unknown. METHODS: To identify patients with DSRCT without extraperitoneal metastases (EPM) who underwent CCRS between 1991 and 2015, a retrospective nation-wide survey was conducted by crossing the prospective and retrospective databases of the French Network for Rare Peritoneal Malignancies, French Reference Network in Sarcoma Pathology, French Sarcoma Clinical Network and French Pediatric Cancer Society. RESULTS: Among the 107 patients with DSRCT, 48 had no EPM and underwent CCRS. The median peritoneal cancer index (PCI) was 9 (range: 2-27). Among these 48 patients, 38 (79%) had pre- and/or postoperative chemotherapy and 23 (48%) postoperative whole abdominopelvic radiotherapy (WAP-RT). Intraperitoneal chemotherapy was administered to 11 patients (23%): two received early postoperative intraperitoneal chemotherapy (EPIC) and nine HIPEC. After a median follow-up of 30 months, the median overall survival (OS) of the entire cohort was 42 months. The 2-y and 5-y OS were 72% and 19%. The 2-y and 5-y disease-free survival (DFS) were 30% and 12%. WAP-RT was the only variable associated with longer peritoneal recurrence-free survival and DFS after CCRS. The influence of HIPEC/EPIC on OS and DFS was not statistically conclusive. CONCLUSION: The benefit of HIPEC is still unknown and should be evaluated in a prospective trial. The value of postoperative WAP-RT seems to be confirmed.

WT1 splicing alterations in Wilms' tumors.

Hereditary and sporadic forms of tumors are generally related to germ-line and somatic mutations of the same tumor suppressor gene. Unexpectedly, in Wilms' tumor, somatic mutations of the WT1 gene were found only occasionally in sporadic cases, although constitutional mutations of this gene are clearly associated with predisposition. It has been suggested that abnormal splicing may be another mode of somatic WT1 alteration. However, this idea was based on the analysis of a small series of tumors, precluding accurate evaluation of the frequency of such changes. To investigate WT1 changes at the somatic level in more detail, we analyzed the levels of the four isoform transcripts produced by alternative splicing events in a large series of 50 tumors, normal mature kidneys, and fetal kidneys. We characterized splicing alterations in 63% of sporadic Wilms' tumors. Moreover, taking into account the decreased and increased overall levels of WT1 mRNA, the percentage of sporadic tumors with changes in WT1 expression reached 90%. Whether and how these alterations of expression play a role in the tumorigenic process remain to be evaluated.

Prevention of bone marrow and cardiac graft rejection in an H-2 haplotype disparate mouse combination by an anti-LFA-1 antibody.

The aim of the present study was to compare the preventive effect of a nondepleting monoclonal antibody specific for the LFA-1 alpha chain (CD11a) on the rejection of bone marrow, vascularized cardiac, and nonvascularized skin grafts in the same haplotype-disparate mouse strain combination. A 7-day treatment with a total dose of 0.5 mg of anti-LFA-1 antibody (H-129) had no effect on the rejection of BDF1(H-2b/d) skin grafts by CDF1 (H-2k/d)-treated mice. In contrast, the same treatment regimen significantly prolonged the survival of BDF1 cardiac allografts in CDF1 mice: 7 out of 10 mice had a functional graft after 70 days, whereas all control mice had rejected their graft by 11 days. Nevertheless, cardiac allografts were ultimately rejected. In contrast, infusion of anti-LFA-1 antibody was able to promote definitive engraftment of T-depleted BDF1 marrow in 9 gray-irradiated CDF1 recipients: in surviving mice, engraftment increased from 10% in controls to 78% in antibody-treated recipients. In mice that tolerated their cardiac graft for more than 70 days, there was a slight delay in the rejection of donor skin graft but no in vitro evidence of tolerance. In contrast, mice with successful marrow engraftment did not reject donor skin graft and failed to mount proliferative and cytotoxic responses against donor alloantigens, whatever the percentage of engrafted donor leukocytes. These results indicate that a nondepleting anti-LFA-1 antibody can efficiently protect against rejection of MHC-incompatible heart and bone marrow. The protective effect of anti-LFA-1 antibody was associated with the induction of T cell tolerance toward donor antigens after bone marrow transplantation.