The Evidence for External Beam Radiotherapy in High-Risk Neuroblastoma of Childhood: A Systematic Review

A Randomised Phase II Trial to Evaluate the Feasibility of Radiotherapy Dose Escalation, Facilitated by Intensity-Modulated Arc Radiotherapy Techniques, in High-Risk Neuroblastoma

BACKGROUND AND PURPOSE

For high-risk neuroblastoma, planning target volume coverage is often compromised to respect adjacent kidney tolerance. This trial investigated whether intensity-modulated arc radiotherapy techniques (IMAT) could facilitate dose escalation better than conventional techniques.

MATERIALS AND METHODS

Children with high-risk abdominal neuroblastoma referred for radiotherapy to the primary tumour site and involved regional lymph nodes were randomised to receive either standard dose (21 Gy in 14 fractions) or escalated dose (36 Gy in 24 fractions) radiotherapy. Dual planning with both a conventional anterior-posterior parallel opposed pair radiotherapy technique and an IMAT technique was performed. The quality of target volume and organ-at-risk delineation, and dosimetric plans, were externally reviewed. Dosimetric parameters were used to judge the superior technique for treatment. This feasibility trial was not powered to detect improvement in outcome with dose escalation.

RESULTS

Between 2017 and 2020, 50 patients were randomised and dual-planned. The IMAT technique was judged more favourable in 48 patients. In all patients randomised to receive 36 Gy, IMAT would have permitted delivery of the full dose (median D50% 36.0 Gy, inter-quartile range 36.0-36.1 Gy) to the target volume, whereas dose compromise would have been required with conventional planning (median D50% 35.6 Gy, inter-quartile range 28.7-35.9 Gy).

CONCLUSION

IMAT facilitates safe dose escalation to 36 Gy in patients receiving radiotherapy for neuroblastoma. The value of dose escalation is now being evaluated in a current prospective phase III randomised trial.

Image guidance and interfractional anatomical variation in paediatric abdominal radiotherapy

OBJECTIVES

To identify variables predicting interfractional anatomical variations measured with cone-beam CT (CBCT) throughout abdominal paediatric radiotherapy, and to assess the potential of surface-guided radiotherapy (SGRT) to monitor these changes.

METHODS

Metrics of variation in gastrointestinal (GI) gas volume and separation of the body contour and abdominal wall were calculated from 21 planning CTs and 77 weekly CBCTs for 21 abdominal neuroblastoma patients (median 4 years, range: 2 - 19 years). Age, sex, feeding tubes, and general anaesthesia (GA) were explored as predictive variables for anatomical variation. Furthermore, GI gas variation was correlated with changes in body and abdominal wall separation, as well as simulated SGRT metrics of translational and rotational corrections between CT/CBCT.

RESULTS

GI gas volumes varied 74 ± 54 ml across all scans, while body and abdominal wall separation varied 2.0 ± 0.7 mm and 4.1 ± 1.5 mm from planning, respectively. Patients < 3.5 years (p = 0.04) and treated under GA (p < 0.01) experienced greater GI gas variation; GA was the strongest predictor in multivariate analysis (p < 0.01). Absence of feeding tubes was linked to greater body contour variation (p = 0.03). GI gas variation correlated with body (R = 0.53) and abdominal wall (R = 0.63) changes. The strongest correlations with SGRT metrics were found for anterior-posterior translation (R = 0.65) and rotation of the left-right axis (R = -0.36).

CONCLUSIONS

Young age, GA, and absence of feeding tubes were linked to stronger interfractional anatomical variation and are likely indicative of patients benefiting from adaptive/robust planning pathways. Our data suggest a role for SGRT to inform the need for CBCT at each treatment fraction in this patient group.

ADVANCES IN KNOWLEDGE

This is the first study to suggest the potential role of SGRT for the management of internal interfractional anatomical variation in paediatric abdominal radiotherapy.

Therapy resistance in neuroblastoma: Mechanisms and reversal strategies

Neuroblastoma is one of the most common pediatric solid tumors that threaten the health of children, accounting for about 15% of childhood cancer-related mortality in the United States. Currently, multiple therapies have been developed and applied in clinic to treat neuroblastoma including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. However, the resistance to therapies is inevitable following long-term treatment, leading to treatment failure and cancer relapse. Hence, to understand the mechanisms of therapy resistance and discover reversal strategies have become an urgent task. Recent studies have demonstrated numerous genetic alterations and dysfunctional pathways related to neuroblastoma resistance. These molecular signatures may be potential targets to combat refractory neuroblastoma. A number of novel interventions for neuroblastoma patients have been developed based on these targets. In this review, we focus on the complicated mechanisms of therapy resistance and the potential targets such as ATP-binding cassette transporters, long non-coding RNAs, microRNAs, autophagy, cancer stem cells, and extracellular vesicles. On this basis, we summarized recent studies on the reversal strategies to overcome therapy resistance of neuroblastoma such as targeting ATP-binding cassette transporters, MYCN gene, cancer stem cells, hypoxia, and autophagy. This review aims to provide novel insight in how to improve the therapy efficacy against resistant neuroblastoma, which may shed light on the future directions that would enhance the treatment outcomes and prolong the survival of patients with neuroblastoma.

Prognostic value of texture analysis of the primary tumour in high-risk neuroblastoma: An 18 F-DOPA PET study

PURPOSE

To evaluate the prognostic value of texture analysis of the primary tumour with ¹⁸ fluorine-dihydroxyphenylalanine positron emission tomography/X-ray computed tomography (¹⁸ F-DOPA PET/CT) in patients affected by high-risk neuroblastoma (HR-NBL).

METHODS

We retrospectively analysed 18 patients with HR-NBL, which had been prospectively enrolled in the course of a previous trial investigating the diagnostic role of ¹⁸ F-DOPA PET/CT at the time of the first onset. Texture analysis of the primary tumour was carried out on the PET images using LifeX. Conventional indices, histogram parameters, grey level co-occurrence (GLCM), run-length (GLRLM), neighbouring difference (NGLDM) and zone-length (GLZLM) matrices parameter were extracted; their values were compared with the overall metastatic load, expressed by means of whole-body metabolic burden (WBMB) score and the progression-free/overall survival (PFS and OS).

RESULTS

There was a direct correlation between WBMB and radiomics parameter describing uptake intensity (SUV_mean : p = .004) and voxel heterogeneity (entropy: p = .026; GLCM_Contrast: p = .001). Conversely, texture indices of homogeneity showed an inverse correlation with WBMB (energy: p = .026; GLCM_Homogeneity: p = .006). On the multivariate model, WBMB (p < .01) and the first standardised uptake value (SUV) quartile (p < .001) predicted PFS; OS was predicted by WBMB and the N-myc proto-oncogene protein (MYCN) amplification (p < .05) for both.

CONCLUSIONS

Textural parameters describing heterogeneity and metabolic intensity of the primary HR-NBL are closely associated with its overall metastatic burden. In turn, the whole-body tumour load appears to be one of the most relevant predictors of progression-free and overall survival.

A Phase II Trial of a Personalized, Dose-Intense Administration Schedule of 177Lutetium-DOTATATE in Children With Primary Refractory or Relapsed High-Risk Neuroblastoma-LuDO-N

Background

Half the children with high-risk neuroblastoma die with widespread metastases. Molecular radiotherapy is an attractive systemic treatment for this relatively radiosensitive tumor. 131I-mIBG is the most widely used form in current use, but is not universally effective. Clinical trials of 177Lutetium DOTATATE have so far had disappointing results, possibly because the administered activity was too low, and the courses were spread over too long a period of time, for a rapidly proliferating tumor. We have devised an alternative administration schedule to overcome these limitations. This involves two high-activity administrations of single agent 177Lu-DOTATATE given 2 weeks apart, prescribed as a personalized whole body radiation absorbed dose, rather than a fixed administered activity. "A phase II trial of 177Lutetium-DOTATATE in children with primary refractory or relapsed high-risk neuroblastoma - LuDO-N" (EudraCT No: 2020-004445-36, ClinicalTrials.gov Identifier: NCT04903899) evaluates this new dosing schedule.

Methods

The LuDO-N trial is a phase II, open label, multi-center, single arm, two stage design clinical trial. Children aged 18 months to 18 years are eligible. The trial is conducted by the Nordic Society for Pediatric Hematology and Oncology (NOPHO) and it has been endorsed by SIOPEN (https://www.siopen.net). The Karolinska University Hospital, is the sponsor of the LuDO-N trial, which is conducted in collaboration with Advanced Accelerator Applications, a Novartis company. All Scandinavian countries, Lithuania and the Netherlands participate in the trial and the UK has voiced an interest in joining in 2022.

Results

The pediatric use of the Investigational Medicinal Product (IMP) 177Lu-DOTATATE, as well as non-IMPs SomaKit TOC® (68Ga-DOTATOC) and LysaKare® amino acid solution for renal protection, have been approved for pediatric use, within the LuDO-N Trial by the European Medicines Agency (EMA). The trial is currently recruiting. Recruitment is estimated to be finalized within 3-5 years.

Discussion

In this paper we present the protocol of the LuDO-N Trial. The rationale and design of the trial are discussed in relation to other ongoing, or planned trials with similar objectives. Further, we discuss the rapid development of targeted radiopharmaceutical therapy and the future perspectives for developing novel therapies for high-risk neuroblastoma and other pediatric solid tumors.

Risk of radiation-induced second malignant neoplasms from photon and proton radiotherapy in paediatric abdominal neuroblastoma

BACKGROUND AND PURPOSE

State-of-the-art radiotherapy modalities have the potential of reducing late effects of treatment in childhood cancer survivors. Our aim was to investigate the carcinogenic risk associated with 3D conformal (photon) radiation (3D-CRT), intensity modulated arc therapy (IMAT) and pencil beam scanning proton therapy (PBS-PT) in the treatment of paediatric abdominal neuroblastoma.

MATERIALS AND METHODS

The risk of radiation-induced second malignant neoplasm (SMN) was estimated using the concept of organ equivalent dose (OED) for eleven organs (lungs, rectum, colon, stomach, small intestine, liver, bladder, skin, central nervous system (CNS), bone, and soft tissues). The risk ratio (RR) between radiotherapy modalities and lifetime absolute risks (LAR) were reported for twenty abdominal neuroblastoma patients (median, 4y; range, 1-9y) historically treated with 3D-CRT that were also retrospectively replanned for IMAT and PBS-PT.

RESULTS

The risk of SMN due to primary radiation was reduced in PBS-PT against 3D-CRT and IMAT for most patients and organs. The RR across all organs ranged from 0.38 ± 0.22 (bladder) to 0.98 ± 0.04 (CNS) between PBS-PT and IMAT, and 0.12 ± 0.06 (rectum and bladder) to 1.06 ± 0.43 (bone) between PBS-PT and 3D-CRT. The LAR for most organs was within 0.01-1% (except the colon) with a cumulative risk of 21 ± 13%, 35 ± 14% and 35 ± 16% for PBS-PT, IMAT and 3D-CRT, respectively.

CONCLUSIONS

PBS-PT was associated with the lowest risk of radiation-induced SMN compared to IMAT and 3D-CRT in abdominal neuroblastoma treatment. Other clinical endpoints and plan robustness should also be considered for optimal plan selection.

Inhibition of glycolysis and mitochondrial respiration promotes radiosensitisation of neuroblastoma and glioma cells

BACKGROUND

Neuroblastoma accounts for 7% of paediatric malignancies but is responsible for 15% of all childhood cancer deaths. Despite rigorous treatment involving chemotherapy, surgery, radiotherapy and immunotherapy, the 5-year overall survival rate of high-risk disease remains < 40%, highlighting the need for improved therapy. Since neuroblastoma cells exhibit aberrant metabolism, we determined whether their sensitivity to radiotherapy could be enhanced by drugs affecting cancer cell metabolism.

METHODS

Using a panel of neuroblastoma and glioma cells, we determined the radiosensitising effects of inhibitors of glycolysis (2-DG) and mitochondrial function (metformin). Mechanisms underlying radiosensitisation were determined by metabolomic and bioenergetic profiling, flow cytometry and live cell imaging and by evaluating different treatment schedules.

RESULTS

The radiosensitising effects of 2-DG were greatly enhanced by combination with the antidiabetic biguanide, metformin. Metabolomic analysis and cellular bioenergetic profiling revealed this combination to elicit severe disruption of key glycolytic and mitochondrial metabolites, causing significant reductions in ATP generation and enhancing radiosensitivity. Combination treatment induced G2/M arrest that persisted for at least 24 h post-irradiation, promoting apoptotic cell death in a large proportion of cells.

CONCLUSION

Our findings demonstrate that the radiosensitising effect of 2-DG was significantly enhanced by its combination with metformin. This clearly demonstrates that dual metabolic targeting has potential to improve clinical outcomes in children with high-risk neuroblastoma by overcoming radioresistance.

Pencil Beam Scanning Proton Therapy Case Selection for Paediatric Abdominal Neuroblastoma: Effects of Tumour Location and Bowel Gas

AIMS

Pencil beam scanning (PBS) proton therapy is an increasingly used radiation modality for childhood malignancies due to its ability to minimise dose to surrounding organs. However, the dosimetry is extremely sensitive to anatomical and density changes. The aims of this study were to investigate if there is a dosimetric benefit or detriment with PBS for paediatric abdominal neuroblastoma, assess gastrointestinal air variability and its dosimetric consequences, plus identify if there are factors that could assist case selection for PBS referral.

MATERIALS AND METHODS

Twenty neuroblastoma cases were double-planned with PBS and intensity-modulated arc therapy (IMAT). Cases were divided into unilateral, midline unilateral and midline bilateral locations in relation to the kidneys. Plans were recalculated after the gastrointestinal volume was simulated as air (Hounsfield Units -700) and water (Hounsfield Units 0), then compared with nominal plans (recalculated - nominal, ΔD). Forty-three weekly cone beam computed tomography scans were analysed to quantify gastrointestinal air variability during treatment.

RESULTS

PBS reduced the mean dose to normal tissues at all tumour locations, particularly unilateral tumours. However, 15% had better dosimetry with IMAT, all of which were midline tumours. Increased gastrointestinal air caused significant compromises to PBS versus IMAT plans for midline tumours [median/maximum ΔD95% clinical target volume (CTV) -2.4%/-15.7% PBS versus 1.4%/0% IMAT, P = 0.003], whereas minimal impact was observed for unilateral tumours (ΔD95% CTV -0.5%/-1.9% PBS versus 0.5%/-0.5% IMAT, P = 0.008). D95% CTV was significantly decreased in PBS plans if planning target volume (PTV) ≥400 cm3 (median -4.1%, P = 0.001) or PTV extension ≥60% anterior to vertebral body (-2.1%, P = 0.002). A larger variation in gastrointestinal air was observed in patients treated under general anaesthesia (median 38.4%) versus awake (11.5%); P = 0.004.

CONCLUSION

In this planning study, tumours at the unilateral location consistently showed improved dose reductions to normal tissue with minimal dose degradation from increased gastrointestinal air with PBS plans. Tumour location, PTV volume and anterior extension of PTV are useful characteristics in facilitating patient selection for PBS.

Proton Beam Therapy for Children With Neuroblastoma: Experiences From the Prospective KiProReg Registry

Objective

Radiotherapy (RT) is an integral part of the interdisciplinary treatment of patients with high-risk neuroblastoma (NB). With the continuous improvements of outcome, the interest in local treatment strategies that reduce treatment-related side effects while achieving optimal oncological results is growing. Proton beam therapy (PBT) represents a promising alternative to conventional photon irradiation with regard to the reduction of treatment burden.

Method

Retrospective analysis of children with high or intermediate risk NB receiving PBT of the primary tumor site during first-line therapy between 2015 and 2020 was performed. Data from the prospective in-house registry Standard Protonentherapie WPE - Kinder- (KiProReg) with respect to tumor control and treatment toxicity were analyzed. Adverse events were classified according to CTCAE Version 4 (V4.0) before, during, and after PBT.

Results

In total, 44 patients (24 male, 20 female) with high (n = 39) or intermediate risk NB (n = 5) were included in the analysis. Median age was 3.4 years (range, 1.4-9.9 years). PBT doses ranged from 21.0 to 39.6 Gray (Gy) (median 36.0 Gy). Five patients received PBT to the MIBG-avid residual at the primary tumor site at time of PBT according to the NB-2004 protocol. In 39 patients radiation was given to the pre-operative tumor bed with or without an additional boost in case of residual tumor. After a median follow-up (FU) of 27.6 months, eight patients developed progression, either local recurrence (n = 1) or distant metastases (n = 7). Four patients died due to tumor progression. At three years, the estimated local control, distant metastatic free survival, progression free survival, and overall survival was 97.7, 84.1, 81.8, and 90.9%, respectively. During radiation, seven patients experienced higher-grade (CTCAE ≥ °3) hematologic toxicity. No other higher grade acute toxicity occurred. After PBT, one patient developed transient myelitis while receiving immunotherapy. No higher grade long-term toxicity was observed up to date.

Conclusion

PBT was a well tolerated and effective local treatment in children with high and intermediate risk NB. The role of RT in an intensive multidisciplinary treatment regimen remains to be studied in the future in order to better define timing, doses, target volumes, and general need for RT in a particularly sensitive cohort of patients.

MicroRNA-145 overexpression inhibits neuroblastoma tumorigenesis in vitro and in vivo

Neuroblastoma (NB) is responsible for 15% of all childhood cancer deaths. Despite advances in treatment and disease management, the overall 5-year survival rates remain poor in high-risk disease (25-40%). It is well known that miR-145 functions as a tumor suppressor in several types of cancer. However, the impact of miR-145 on NB is still ambiguous. Our aim was to investigate the potential tumor suppressive role and mechanisms of miR-145 in high-risk neuroblastoma. Expression levels of miR-145 in tissues and cells were determined using RT-qPCR. The effect of miR-145 on cell viability was evaluated using MTT assays, apoptosis levels were determined using TUNEL staining, and the MTDH protein expression was determined using western blot and RT-PCR. Luciferase reporter plasmids were constructed to confirm direct targeting for MTDH. The results showed that miR-145 expression was significantly lower in high-risk MYCN amplified (MNA) tumors and low miR-145 expression was associated with worse EFS and OS in our cohort. Over-expression of miR-145 reduced cell viability and increased apoptosis in SH-SY-5Y cells. We identified MTDH as a direct target for miR-145 in SH-SY-5Y cells. Targeting MTDH has the similar results as miR-145 overexpression. Our findings suggest that low miR-145 expression was associated with poor prognosis in patients with NB, and the overexpression of miR-145 inhibited NB cells growth by down-regulating MTDH, thus providing a potential target for the development of microRNA-based approach for NB therapy.

Dosimetric comparison of tomotherapy and volumetric-modulated arc therapy for children with neuroblastoma

Importance

Irradiation treatment for pediatric patients with neuroblastoma represents a major challenge due to the pediatric dose limits for critical structures and the necessity of sufficient dose coverage of the clinical target volume for local control.

Objective

To investigate dosimetric differences between tomotherapy (TOMO) and volumetric‐modulated arc therapy (VMAT) as retroperitoneal radiotherapy for children with neuroblastoma.

Methods

Eight patients who received retroperitoneal radiotherapy for neuroblastoma were selected for comparison of TOMO and VMAT treatment plans. The D_min, D_max, D_mean, D₉₅, D₂, and D₉₈ of planning target volume (PTV), conformity index (CI), heterogeneity index (HI), and organs at risk (OARs) parameters were compared. Delivery machine unit (MU) and image‐guide radiotherapy solution results were also compared.

Results

All patients received a cumulative dose of 19.5 Gy to the PTV. VMAT showed higher CI (0.93 ± 0.02), compared with TOMO (0.87 ± 0.03, P < 0.001). Notably, the average PTV HI was significantly better using TOMO (1.05 ± 0.01) than VMAT (1.08 ± 0.02, P = 0.003). Compared with VMAT, the D_min, D₉₅, and D₉₈ all exhibited increases in TOMO; D_max variation was less than 1% in TOMO. The D_0.1cc for the spinal cord and D_2cc for the small intestine were better in TOMO in terms of OARs. However, TOMO had more MUs and required a longer delivery time.

Interpretation

Both planning techniques are capable of producing high‐ quality treatment plans. TOMO is superior for PTV coverage, but inferior for CI. TOMO requires extra treatment time; its cost is greater than the cost of VMAT.

A phase IIa trial of molecular radiotherapy with 177-lutetium DOTATATE in children with primary refractory or relapsed high-risk neuroblastoma

PURPOSE

The objective of this phase IIa, open-label, single-centre, single-arm, two-stage clinical trial was to evaluate the safety and activity of 177-lutetium DOTATATE (LuDO) molecular radiotherapy in neuroblastoma.

METHODS

Children with relapsed or refractory metastatic high-risk neuroblastoma were treated with up to four courses of LuDO. The administered activity was 75 to 100 MBq kg-1 per course, spaced at 8- to 12-week intervals. Outcomes were assessed by the International Neuroblastoma Response Criteria (primary outcome), progression-free survival (PFS), and overall survival (OS).

RESULTS

The trial recruited 21 patients; eight received the planned four courses. There was dose-limiting haematologic toxicity in one case, but no other significant haematologic or renal toxicities. None of 14 evaluable patients had an objective response at 1 month after completion of treatment (Wilson 90% CI 0.0, 0.16; and 95% CI is 0.0, 0.22). The trial did not therefore proceed to the second stage. The median PFS was 2.96 months (95% CI 1.71, 7.66), and the median OS was 13.0 months (95% CI 2.99, 21.52).

CONCLUSION

In the absence of any objective responses, the use of LuDO as a single agent at the dose schedule used in this study is not recommended for the treatment of neuroblastoma. There are several reasons why this treatment schedule may not have resulted in objective responses, and as other studies do show benefit, the treatment should not be regarded as being of no value. Further trials designed to overcome this schedule's limitations are required.

TRIAL REGISTRATION

ISRCTN98918118; URL: https://www.isrctn.com/search?q=98918118.

Influence of Surgical Excision on the Survival of Patients With Stage 4 High-Risk Neuroblastoma: A Report From the HR-NBL1/SIOPEN Study

PURPOSE

To evaluate the impact of surgeon-assessed extent of primary tumor resection on local progression and survival in patients in the International Society of Pediatric Oncology Europe Neuroblastoma Group High-Risk Neuroblastoma 1 trial.

PATIENTS AND METHODS

Patients recruited between 2002 and 2015 with stage 4 disease > 1 year or stage 4/4S with MYCN amplification < 1 year who had completed induction without progression, achieved response criteria for high-dose therapy (HDT), and had no resection before induction were included. Data were collected on the extent of primary tumor excision, severe operative complications, and outcome.

RESULTS

A total of 1,531 patients were included (median observation time, 6.1 years). Surgeon-assessed extent of resection included complete macroscopic excision (CME) in 1,172 patients (77%) and incomplete macroscopic resection (IME) in 359 (23%). Surgical mortality was 7 (0.46%) of 1,531. Severe operative complications occurred in 142 patients (9.7%), and nephrectomy was performed in 124 (8.8%). Five-year event-free survival (EFS) ± SE (0.40 ± 0.01) and overall survival (OS; 0.45 ± 0.02) were significantly higher with CME compared with IME (5-year EFS, 0.33 ± 0.03; 5-year OS, 0.37 ± 0.03; P < .001 and P = .004). The cumulative incidence of local progression (CILP) was significantly lower after CME (0.17 ± 0.01) compared with IME (0.30 ± 0.02; P < .001). With immunotherapy, outcomes were still superior with CME versus IME (5-year EFS, 0.47 ± 0.02 v 0.39 ± 0.04; P = .038); CILP was 0.14 ± 0.01 after CME and 0.27 ± 0.03 after IME (P < .002). A hazard ratio of 1.3 for EFS associated with IME compared with CME was observed before and after the introduction of immunotherapy (P = .030 and P = .038).

CONCLUSION

In patients with stage 4 high-risk neuroblastoma who have responded to induction therapy, CME of the primary tumor is associated with improved survival and local control after HDT, local radiotherapy (21 Gy), and immunotherapy.

Extended induction chemotherapy does not improve the outcome for high-risk neuroblastoma patients: results of the randomized open-label GPOH trial NB2004-HR

BACKGROUND

Long-term survival of high-risk neuroblastoma patients is still below 50% despite intensive multimodal treatment. This trial aimed to address whether the addition of two topotecan-containing chemotherapy courses compared to standard induction therapy improves event-free survival (EFS) of these patients.

PATIENTS AND METHODS

An open-label, multicenter, prospective randomized controlled trial was carried out at 58 hospitals in Germany and Switzerland. Patients aged 1-21 years with stage 4 neuroblastoma and patients aged 6 months to 21 years with MYCN-amplified tumors were eligible. The primary endpoint was EFS. Patients were randomly assigned to standard induction therapy with six chemotherapy courses or to experimental induction chemotherapy starting with two additional courses of topotecan, cyclophosphamide, and etoposide followed by standard induction chemotherapy (eight courses in total). After induction chemotherapy, all patients received high-dose chemotherapy with autologous hematopoietic stem cell rescue and isotretinoin for consolidation. Radiotherapy was applied to patients with active tumors at the end of induction chemotherapy.

RESULTS

Of 536 patients enrolled in the trial, 422 were randomly assigned to the control arm (n = 211) and the experimental arm (n = 211); the median follow-up time was 3.32 years (interquartile range 1.65-5.92). At data lock, the 3-year EFS of experimental and control patients was 34% and 32% [95% confidence Interval (CI) 28% to 40% and 26% to 38%; P = 0.258], respectively. Similarly, the 3-year overall survival of the patients did not differ [54% and 48% (95% CI 46% to 62% and 40% to 56%), respectively; P = 0.558]. The response to induction chemotherapy was not different between the arms. The median number of non-fatal toxicities per patient was higher in the experimental group while the median number of toxicities per chemotherapy course was not different.

CONCLUSION

While the burden for the patients was increased by prolonging the induction chemotherapy and the toxicity, the addition of two topotecan-containing chemotherapy courses did not improve the EFS of high-risk neuroblastoma patients and thus cannot be recommended. CLINICAL TRIALS.

GOV NUMBER

NCT number 03042429.