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Background: We assessed whether relapse-free survival (RFS; time until recurrence/death) is a valid surrogate for overall survival (OS) among resected stage II-III melanoma patients through a meta-analysis of randomized controlled trials., Methods: Individual patient data (IPD) on RFS and OS were collected from 5826 patients enrolled in 11 randomized adjuvant trials comparing interferon (IFN) to observation. In addition, IPD from two studies comparing IFN and vaccination in 989 patients were included. A two-level modeling approach was used for assessing Spearman's patient-level correlation (rho) of RFS and OS and the trial-level coefficient of determination (R²) of the treatment effects on RFS and on OS. The results were validated externally in 13 adjuvant studies without available IPD. We then tested the results on the European Organisation for Research and Treatment of Cancer (EORTC) 18071 double-blind trial comparing ipilimumab 10 mg/kg with placebo, which showed a statistically significant impact of the checkpoint inhibitor on RFS and OS. All statistical tests were two-sided., Results: With a median follow-up of seven years, 12 of 13 trials showed a consistency between the IFN vs No IFN differences regarding RFS (hazard ratio [HR]RFS = 0.88) and OS (HROS = 0.91), but the small trial, Eastern Cooperative Oncology Group 2696, was an outlier (HRRFS = 0.72 vs HROS = 1.11). Therefore, even if rho was high, R² was low and could not reliably be estimated. Based on the 12 trials, rho remained high (0.89), and the hazard ratios for RFS and OS were strongly correlated (R² = 0.91). The surrogate threshold effect for RFS was estimated to be 0.77. For the EORTC 18071 trial, the hazard ratio for RFS was 0.75, predicting an effect of ipilimumab on OS. This was subsequently confirmed (HROS = 0.72, 95.1% confidence interval = 0.58 to 0.88, P = .001)., Conclusions: In high-risk stage II-III melanoma, RFS appeared to be a valid surrogate end point for OS for adjuvant randomized studies assessing interferon or a checkpoint inhibitor. In future similar adjuvant studies, a hazard ratio for RFS of 0.77 or less would predict a treatment impact on OS., (© The Author 2017. Published by Oxford University Press.)

Background: Many randomised trials assessing interferon-α (IFN-α) as adjuvant therapy for high-risk malignant melanoma have been undertaken. To better assess the role of IFN-α, an individual patient data (IPD) meta-analysis of these trials was undertaken., Methods: IPD was sought from all randomised trials of adjuvant IFN-α versus no IFN-α for high-risk melanoma. Primary outcomes were event-free survival (EFS) and overall survival (OS). Standard methods for quantitative IPD meta-analysis were used. Subgroup analyses by dose, duration of treatment and various patient and disease-specific parameters were performed., Findings: Fifteen trials were included in the analysis (eleven with IPD). EFS was significantly improved with IFN-α (hazard ratio [HR] = 0.86, CI 0.81-0.91; P < 0.00001), as was OS (HR = 0.90, CI 0.85-0.97; P = 0.003). The absolute differences in EFS at 5 and 10 years were 3.5% and 2.7%, and for OS were 3.0% and 2.8% respectively in favour of IFN-α. There was no evidence that the benefit of IFN-α differed depending on dose or duration of treatment, or by age, gender, site of primary tumour, disease stage, Breslow thickness, or presence of clinical nodes. Only for ulceration was there evidence of an interaction (test for heterogeneity: P = 0.04 for EFS; P = 0.002 for OS); only patients with ulcerated tumours appeared to obtain benefit from IFN-α., Conclusion: This meta-analysis provides clear evidence that adjuvant IFN-α significantly reduces the risk of relapse and improves survival and shows no benefit for higher doses compared to lower doses. The increased benefit in patients with ulcerated tumours, and lack of benefit in patients without ulceration, needs further investigation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Multiple myeloma is a malignancy of plasma cells accounting for approximately 1% of cancers and 12% of haematological malignancies. The first-in-class proteasome inhibitor, bortezomib, is commonly used to treat newly diagnosed as well as relapsed/refractory myeloma, either as single agent or combined with other therapies., Objectives: We conducted a systematic review and meta-analysis to assess the effects of bortezomib on overall survival (OS), progression-free survival (PFS), response rate (RR), health-related quality of life (HRQoL), adverse events (AEs) and treatment-related death (TRD)., Search Methods: We searched MEDLINE, the Cochrane Central Register of Controlled Trials and EMBASE (till 27 January 2016) as well as conference proceedings and clinical trial registries for randomised controlled trials (RCTs)., Selection Criteria: We included randomised controlled trials (RCTs) that compared i) bortezomib versus no bortezomib with the same background therapy in each arm; ii) bortezomib versus no bortezomib with different background therapy in each arm or compared to other agent(s) and iii) bortezomib dose comparisons and comparisons of different treatment administrations and schedules., Data Collection and Analysis: Two review authors independently extracted outcomes data and assessed risk of bias. We extracted hazard ratios (HR) and their confidence intervals for OS and PFS and odds ratios (OR) for response rates, AEs and TRD. We contacted trial authors to provide summary statistics if missing. We estimated Logrank statistics which were not available. We extracted HRQoL data, where available., Main Results: We screened a total of 3667 records, identifying 16 relevant RCTs involving 5626 patients and included 12 trials in the meta-analyses. All trials were randomised and open-label studies. Two trials were published in abstract form and therefore we were unable to assess potential risk of bias in full.There is moderate-quality evidence that bortezomib prolongs OS (four studies, 1586 patients; Peto OR 0.77, 95% CI 0.65 to 0.92) and PFS (five studies, 1855 patients; Peto OR 0.65, 95% CI 0.57 to 0.74) from analysing trials of bortezomib versus no bortezomib with the same background therapy in each arm.There is high-quality evidence that bortezomib prolongs OS (five studies, 2532 patients; Peto OR 0.76, 95% CI 0.67 to 0.88) but low-quality evidence for PFS (four studies, 2489 patients; Peto OR 0.67, 95% CI 0.61 to 0.75) from analysing trials of bortezomib versus no bortezomib with different background therapy in each arm or compared to other agent(s).Four trials (N = 716) examined different doses, methods of administrations and treatment schedules and were reviewed qualitatively only.We identified four trials in the meta-analysis that measured time to progression (TTP) and were able to extract and analyse PFS data for three of the studies, while in the case of one study, we included TTP data as PFS data were not available. We therefore did not analyse TTP separately in this review.Patients treated with bortezomib have increased risk of thrombocytopenia, neutropenia, gastro-intestinal toxicities, peripheral neuropathy, infection and fatigue with the quality of evidence highly variable. There is high-quality evidence for increased risk of cardiac disorders from analysing trials of bortezomib versus no bortezomib with different background therapy in each arm or versus other agents. The risk of TRD in either comparison group analysed is uncertain due to the low quality of the evidence.Only four trials analysed HRQoL and the data could not be meta-analysed.Subgroup analyses by disease setting revealed improvements in all outcomes, whereas for therapy setting, an improved benefit for bortezomib was observed in all outcomes and subgroups except for OS following consolidation therapy., Authors' Conclusions: This meta-analysis found that myeloma patients receiving bortezomib benefited in terms of OS, PFS and response rate compared to those who did not receive bortezomib. This benefit was observed in trials of bortezomib versus no bortezomib with the same background therapy and in trials of bortezomib versus no bortezomib with different background therapy in each arm or compared to other agent(s). Further evaluation of newer proteasome inhibitors is required to ascertain whether these agents offer an improved risk-benefit profile, while more studies of HRQoL are also required.

Better treatment is required for older patients with acute myeloid leukemia (AML) not considered fit for intensive chemotherapy. We report a randomized comparison of low-dose Ara-C (LDAC) vs the novel nucleoside, clofarabine, in untreated older patients with AML and high-risk myelodysplastic syndrome (MDS). A total of 406 patients with de novo (62%), secondary disease (24%), or high-risk MDS (>10% marrow blasts) (15%), median age 74 years, were randomized to LDAC 20 mg twice daily for 10 days every 6 weeks or clofarabine 20 mg/m(2) on days 1 to 5, both for up to 4 courses. These patients had more adverse demographics than contemporaneous intensively treated patients. The overall remission rate was 28%, and 2-year survival was 13%. Clofarabine significantly improved complete remission (22% vs 12%; hazard ratio [HR] = 0.47 [0.28-0.79]; P = .005) and overall response (38% vs 19%; HR = 0.41 [0.26-0.62]; P < .0001), but there was no difference in overall survival, explained by poorer survival in the clofarabine patients who did not gain complete remission and also following relapse. Clofarabine was more myelosuppressive and required more supportive care. Although clofarabine doubled remission rates, overall survival was not improved overall or in any subgroup. The treatment of patients of the type treated here remains a major unmet need.

Background: Bisphosphonates are specific inhibitors of osteoclastic activity and used in the treatment of patients with multiple myeloma (MM). While bisphosphonates are shown to be effective in reducing vertebral fractures and pain, their role in improving overall survival (OS) remains unclear. This is an update of a Cochrane review first published in 2002 and previously updated in 2010., Objectives: To assess the evidence related to benefits and harms associated with use of various types of bisphosphonates (aminobisphosphonates versus nonamino bisphosphonates) in the management of patients with MM. Our primary objective was to determine whether adding bisphosphonates to standard therapy in MM improves OS and progression-free survival (PFS), and decreases skeletal-related morbidity. Our secondary objectives were to determine the effects of bisphosphonates on pain, quality of life, incidence of hypercalcemia, incidence of bisphosphonate-related gastrointestinal toxicities, osteonecrosis of jaw and hypocalcemia., Search Methods: We searched MEDLINE, LILACS, EMBASE (December 2009 to October 2011) and the Cochrane Controlled Trials Register (all years, latest Issue September 2011) to identify all randomized trials in MM up to October 2011 using a combination of text and MeSH terms. We also handsearched relevant meeting proceedings (December 2009 to October 2011)., Selection Criteria: Any randomized controlled trial (RCT) assessing the role of bisphosphonates and observational studies or case reports examining bisphosphonate-related osteonecrosis of the jaw in patients with MM were eligible for inclusion., Data Collection and Analysis: Two review authors extracted the data. Data were pooled and reported as hazard ratio (HR) or risk ratio (RR) under a random-effects model. Statistical heterogeneity was explored using metaregression., Main Results: In this update, we included 2 studies (2464 patients) that were not part of our last Cochrane review published in 2010. In this review we included 16 RCTs comparing bisphosphonates with either placebo or no treatment and 4 RCTs with a different bisphosphonate as a comparator. The 20 included RCTs enrolled 6692 patients. Overall methodological quality of reporting was moderate. Thirty per cent (6/20) of trials reported the method of generating the randomization sequence. Forty per cent (8/20) of trials had adequate allocation concealment. Withdrawals and dropouts were described in 60% (12/20) of trials. Pooled results showed no direct effect of bisphosphonates on OS compared with placebo or no treatment (HR 0.96, 95% CI 0.82 to 1.13; P = 0.64). However, there was a statistically significant heterogeneity among the included RCTs (I(2) = 55%, P = 0.01) for OS. To explain this heterogeneity we performed a metaregression assessing the relationship between bisphosphonate potency and improvement in OS, which found indicating an OS benefit with zoledronate (P = 0.058). This provided a further rationale for performing network meta-analyses of the various types of bisphosphonates that were not compared head to head in RCTs. Results from network meta-analyses showed superior OS with zoledronate compared with etidronate (HR 0.43, 95% CI 0.16 to 0.86) and placebo (HR 0.61, 95% CI 0.28 to 0.98). However, there was no difference between zoledronate and other bisphosphonates. Pooled analysis did not demonstrate a beneficial effect of bisphosphonates compared with placebo or no treatment in improving PFS (HR 0.70, 95% CI 0.41 to 1.19; P = 0.18) There was no heterogeneity among trials reporting PFS estimates (I(2) = 35%, P = 0.20).Pooled analysis demonstrated a beneficial effect of bisphosphonates compared with placebo or no treatment on prevention of pathological vertebral fractures (RR 0.74, 95% CI 0.62 to 0.89; I(2) = 7%), skeletal-related events (SRE) (RR 0.80, 95% CI 0.72 to 0.89; I(2) = 2%) and amelioration of pain (RR 0.75, 95% CI 0.60 to 0.95; I(2) = 63%). The network meta-analysis did not show any difference in the incidence of osteonecrosis of the jaw (5 RCTs, 3198 patients) between bisphosphonates. Rates of osteonecrosis of the jaw in observational studies (9 studies, 1400 patients) ranged from 0% to 51%. The pooled results (6 RCTs, 1689 patients) showed no statistically significant increase in frequency of gastrointestinal symptoms with the use of bisphosphonates compared with placebo or no treatment (RR 1.23, 95% CI 0.95 to 1.60; P = 0.11).The pooled results (3 RCTs, 1002 patients) showed no statistically significant increase in frequency of hypocalcemia with the use of bisphosphonates compared with placebo or no treatment (RR 2.19, 95% CI 0.49 to 9.74). The network meta-analysis did not show any differences in the incidence of hypocalcemia, renal dysfunction and gastrointestinal toxicity between the bisphosphonates used., Authors' Conclusions: Use of bisphosphonates in patients with MM reduces pathological vertebral fractures, SREs and pain. Assuming a baseline risk of 20% to 50% for vertebral fracture without treatment, between 8 and 20 MM patients should be treated to prevent vertebral fracture(s) in one patient. Assuming a baseline risk of 31% to 76% for pain amelioration without treatment, between 5 and 13 MM patients should be treated to reduce pain in one patient. With a baseline risk of 35% to 86% for SREs without treatment, between 6 and 15 MM patients should be treated to prevent SRE(s) in one patient. Overall, there were no significant adverse effects associated with the administration of bisphosphonates identified in the included RCTs. We found no evidence of superiority of any specific aminobisphosphonate (zoledronate, pamidronate or ibandronate) or nonaminobisphosphonate (etidronate or clodronate) for any outcome. However, zoledronate appears to be superior to placebo and etidronate in improving OS.

Background: The role and dose of anticoagulants in thromboprophylaxis for patients with cancer receiving chemotherapy through central venous catheters (CVCs) is controversial. We therefore assessed whether warfarin reduces catheter-related thrombosis compared with no warfarin and whether the dose of warfarin determines the thromboprophylactic effect., Methods: In 68 clinical centres in the UK, we randomly assigned 1590 patients aged at least 16 years with cancer who were receiving chemotherapy through CVCs to no warfarin, fixed-dose warfarin 1 mg per day, or dose-adjusted warfarin per day to maintain an international normalised ratio between 1.5 and 2.0. Clinicians who were certain of the benefit of warfarin randomly assigned patients to fixed-dose or dose-adjusted warfarin groups. The primary outcome was the rate of radiologically proven, symptomatic catheter-related thrombosis. Analysis was by intention to treat. This trial is registered as an International Standard Randomised Controlled Trial, number ISRCTN 50312145., Findings: Compared with no warfarin (n=404), warfarin (n=408; 324 [79%] on fixed-dose and 84 [21%] on dose-adjusted) did not reduce the rate of catheter-related thromboses (24 [6%] vs 24 [6%]; relative risk 0.99, 95% CI 0.57-1.72, p=0.98). However, compared with fixed-dose warfarin (n=471), dose-adjusted warfarin (n=473) was superior in the prevention of catheter-related thromboses (13 [3%] vs 34 [7%]; 0.38, 0.20-0.71, p=0.002). Major bleeding events were rare; an excess was noted with warfarin compared with no warfarin (7 vs 1, p=0.07) and with dose-adjusted warfarin compared with fixed-dose warfarin (16 vs 7, p=0.09). A combined endpoint of thromboses and major bleeding showed no difference between comparisons. We did not note a survival benefit in either comparison., Interpretation: The findings show that prophylactic warfarin compared with no warfarin is not associated with a reduction in symptomatic catheter-related or other thromboses in patients with cancer and therefore we should consider newer treatments., Funding: Medical Research Council and Cancer Research UK.

Purpose: To assess the effect of adding interferon-alpha (IFN) +/- interleukin-2 (IL-2) to chemotherapy in patients with metastatic melanoma. METHODS A published data meta-analysis of trials of biochemotherapy versus chemotherapy in patients with metastatic melanoma was undertaken. End points evaluated were rates of partial response (PR), complete response (CR) and overall (partial + complete) response (OR); response duration; progression-free survival; overall survival (OS); and toxicity. The only subgroup analysis performed was by type of immunotherapy, with trials divided according to whether IFN only or IFN and IL-2 were administered in the biochemotherapy arm., Results: Eighteen randomized trials were identified: 11 trials of chemotherapy +/- IFN and seven trials of chemotherapy +/- IFN and IL-2. More than 2,600 patients were entered onto the trials, with 555 responses and 2,039 deaths. There was a clear benefit for biochemotherapy for PR (odds ratio = 0.66; 95% CI, 0.53 to 0.82; P = .0001), CR (odds ratio = 0.50; 95% CI, 0.35 to 0.73; P = .0003) and OR (odds ratio = 0.59; 95% CI, 0.49 to 0.72; P < .00001). For OR, these benefits were significant for both the IFN (odds ratio = 0.60; 95% CI, 0.46 to 0.79; P = .0002) and IFN + IL-2 (odds ratio = 0.58; 95% CI, 0.44 to 0.77; P = .0001) subgroups. In contrast, there was no benefit overall in OS (odds ratio = 0.99; 95% CI, 0.91 to 1.08; P = .9), but there was evidence of heterogeneity of treatment effect between the individual trials (P = .006)., Conclusion: This meta-analysis provides a comprehensive summary of all the data currently available, and shows that although biochemotherapy clearly improves response rates, this does not appear to translate into a survival benefit.

The optimum chemotherapy schedule for reinduction of patients with high-risk acute myeloid leukemia (relapsed, resistant/refractory, or adverse genetic disease) is uncertain. The MRC AML (Medical Research Council Acute Myeloid Leukemia) Working Group designed a trial comparing fludarabine and high-dose cytosine (FLA) with standard chemotherapy comprising cytosine arabinoside, daunorubicin, and etoposide (ADE). Patients were also randomly assigned to receive filgrastim (G-CSF) from day 0 until neutrophil count was greater than 0.5 x 10(9)/L (or for a maximum of 28 days) and all-trans retinoic acid (ATRA) for 90 days. Between 1998 and 2003, 405 patients were entered: 250 were randomly assigned between FLA and ADE; 356 to G-CSF versus no G-CSF; 362 to ATRA versus no ATRA. The complete remission rate was 61% with 4-year disease-free survival of 29%. There were no significant differences in the CR rate, deaths in CR, relapse rate, or DFS between ADE and FLA, although survival at 4 years was worse with FLA (16% versus 27%, P = .05). Neither the addition of ATRA nor G-CSF demonstrated any differences in the CR rate, relapse rate, DFS, or overall survival between the groups. In conclusion these findings indicate that FLA may be inferior to standard chemotherapy in high-risk AML and that the outcome is not improved with the addition of either G-CSF or ATRA.

The prognostic significance of FLT3 mutations in acute promyelocytic leukemia (APL) is not firmly established and is of particular interest given the opportunities for targeted therapies using FLT3 inhibitors. We studied 203 patients with PML-RARA-positive APL; 43% of the patients had an FLT3 mutation (65 internal tandem duplications [ITDs], 19 D835/I836, 4 ITD+D835/I836). Both mutations were associated with higher white blood cell (WBC) count at presentation; 75% of the patients with WBC counts of 10 x 10(9)/L or greater had mutant FLT3. FLT3/ITDs were correlated with M3v subtype (P < .001), bcr3 PML breakpoint (P < .001), and expression of reciprocal RARA-PML transcripts (P = .01). Microarray analysis revealed differences in expression profiles among patients with FLT3/ITD, D835/I836, and wild-type FLT3. Patients with mutant FLT3 had a higher rate of induction death (19% vs 9%; P = .04, but no significant difference in relapse risk (28% vs 23%; P = .5) or overall survival (59% vs 67%; P = .2) at 5 years. In in vitro differentiation assays using primary APL blasts (n = 6), the FLT3 inhibitor CEP-701 had a greater effect on cell survival/proliferation in FLT3/ITD+ cells, but this inhibition was reduced in the presence of ATRA. Furthermore, in the presence of CEP-701, ATRA-induced differentiation was reduced in FLT3/ITD+ cells. These data carry implications for the use of FLT3 inhibitors as frontline therapy for APL.

Background: We conducted a randomized comparison of hydroxyurea with anagrelide in the treatment of essential thrombocythemia., Methods: A total of 809 patients with essential thrombocythemia who were at high risk for vascular events received low-dose aspirin plus either anagrelide or hydroxyurea. The composite primary end point was the actuarial risk of arterial thrombosis (myocardial infarction, unstable angina, cerebrovascular accident, transient ischemic attack, or peripheral arterial thrombosis), venous thrombosis (deep-vein thrombosis, splanchnic-vein thrombosis, or pulmonary embolism), serious hemorrhage, or death from thrombotic or hemorrhagic causes., Results: After a median follow-up of 39 months, patients in the anagrelide group were significantly more likely than those in the hydroxyurea group to have reached the primary end point (odds ratio, 1.57; 95 percent confidence interval, 1.04 to 2.37; P=0.03). As compared with hydroxyurea plus aspirin, anagrelide plus aspirin was associated with increased rates of arterial thrombosis (P=0.004), serious hemorrhage (P=0.008), and transformation to myelofibrosis (P=0.01) but with a decreased rate of venous thromboembolism (P=0.006). Patients receiving anagrelide were more likely to withdraw from their assigned treatment (P<0.001). Equivalent long-term control of the platelet count was achieved in both groups., Conclusions: Hydroxyurea plus low-dose aspirin is superior to anagrelide plus low-dose aspirin for patients with essential thrombocythemia at high risk for vascular events., (Copyright 2005 Massachusetts Medical Society.)

Background: Several randomised trials have compared interferon-alpha with control as adjuvant therapy for high-risk malignant melanoma. The results of the individual trials have been either inconclusive or even apparently conflicting. To assess all the available evidence we performed a meta-analysis of these trials., Methods: Standard methods for quantitative meta-analysis based on published data were used. Endpoints evaluated were recurrence-free survival and overall survival. A subgroup analysis by dose of interferon-alpha was performed., Findings: Twelve trials, comprising 14 comparisons of interferon-alpha with control, with results available were identified. Recurrence-free survival was improved with interferon-alpha: hazard ratio 0.83, 95% confidence interval 0.77 to 0.90, p=0.000003. The benefit on overall survival was less clear (0.93, 0.85 to 1.02, p=0.1) and the confidence interval is compatible both with no benefit and with a moderate, but clinically worthwhile, benefit. There was some evidence of a dose response relationship with a significant trend for the benefit of interferon-alpha to increase with increasing dose for recurrence-free survival (test for trend: p=0.02) but not for overall survival (trend: p=0.8)., Interpretation: This meta-analysis provides the most reliable synthesis of the data currently available. Adjuvant interferon-alpha produces clear reductions in recurrence of high-risk melanoma, with some evidence of an effect of dose of interferon-alpha, but it is unclear whether this translates into a worthwhile survival benefit or not. Additional and more mature data are needed to resolve these issues and an individual patient data meta-analysis should be performed.

Background: The survival of older patients with acute myeloid leukemia has not improved. Few clinical trials have been available for older patients who are not considered fit for an intensive chemotherapy approach.Methods: Between December 1998 and November 2003, as part of National Cancer Research Institute Acute Myeloid Leukemia 14 Trial, 217 patients, who were deemed unfit for intensive chemotherapy were randomized to receive low-dose cytarabine (Ara-C) (20 mg twice daily for 10 days) or hydroxyurea with or without all-trans retinoic acid (ATRA).Results: Low-dose ara-C produced a better remission rate (18% vs 1%; odds ratio [OR], 0.15; 95% confidence interval [95% CI], 0.06-0.37; P = .00006) and better overall survival (OR, 0.60; 95% CI, 0.44-0.81; P = .0009), which was accounted for by the achievement of complete remission (CR) (duration of CR: 80 weeks vs 10 weeks for patients with no CR). Patients who had adverse cytogenetics did not benefit. ATRA had no effect. Toxicity scores or supportive care requirements did not differ between the treatment arms.Conclusions: Older, less fit patients have a poor outcome, and few trials have been conducted in this patient group. Low-dose ara-C treatment was superior to best supportive care and hydroxyurea because it had greater success in achieving CR, and it could represent standard care against which new treatments may be compared in this patient group. [ABSTRACT FROM AUTHOR]

Background Based on the randomised Euro-EWING99-R1 trial, vincristine, adriamycin, cyclophosphamide (VAC) may be able to replace vincristine, adriamycin, ifosfamide (VAI) in the treatment of standard-risk Ewing sarcoma. However some heterogeneity of treatment effect by gender was observed. The current exploratory study aimed at investigating the influence of gender on treatment efficacy and acute toxicity. Patients and methods Impact of gender on event-free survival (EFS), acute toxicity by course, switches between treatment arms and cumulative dose of alkylating agents was evaluated in multivariable models adjusted for age including terms to test for heterogeneity of treatment effect by gender. The analysis of the EFS was performed on the intention-to-treat population. Results EFS did not significantly differ between the 509 males and 347 females ( p = 0.33), but an interaction in terms of efficacy was suspected between treatment and gender ( p = 0.058): VAC was associated with poorer EFS than VAI in males, hazard ratio (HR) (VAC/VAI) = 1.37 [95% confidence interval (CI), 0.98–1.90], contrasting with HR = 0.81 [95%CI, 0.53–1.24] in females. Severe toxicity was more frequent in females, whatever the toxicity type. Thirty patients switched from VAI to VAC (9/251 males, 4%, and 21/174 females, 12%) mostly due to renal toxicity, and three from VAC to VAI (2/258 males, 0.8%, and 1/173 females, 0.6%). A reduction of alkylating agent cumulative dose >20% was more frequent in females (15% versus 9%, p = 0.005), with no major difference between VAC and VAI (10% versus 13%, p = 0.15). Conclusion Differences of acute toxicity rate and cumulative doses of alkylating agents could not explain the marginal interaction observed in the Euro-EWING99-R1 trial data. Effects of gender-dependent polymorphism/activity of metabolic enzymes (e.g. known for CYP2B6) of ifosfamide versus cyclophosphamide should be explored. External data are required to further evaluate whether there is heterogeneity of alkylating agent effect by gender. Trial numbers NCT00987636 and EudraCT 2008-003658-13. [ABSTRACT FROM AUTHOR]