Summary Background Gemtuzumab ozogamicin was the first example of antibody-directed chemotherapy in cancer, and was developed for acute myeloid leukaemia. However, randomised trials in which it was ...combined with standard induction chemotherapy in adults have produced conflicting results. We did a meta-analysis of individual patient data to assess the efficacy of adding gemtuzumab ozogamicin to induction chemotherapy in adult patients with acute myeloid leukaemia. Methods We searched PubMed for reports of randomised controlled trials published in any language up to May 1, 2013, that included an assessment of gemtuzumab ozogamicin given to adults (aged 15 years and older) in conjunction with the first course of intensive induction chemotherapy for acute myeloid leukaemia (excluding acute promyelocytic leukaemia) compared with chemotherapy alone. Published data were supplemented with additional data obtained by contacting individual trialists. The primary endpoint of interest was overall survival. We used standard meta-analytic techniques, with an assumption-free (or fixed-effect) method. We also did exploratory stratified analyses to investigate whether any baseline features predicted a greater or lesser benefit from gemtuzumab ozogamicin. Findings We obtained data from five randomised controlled trials (3325 patients); all trials were centrally randomised and open label, with overall survival as the primary endpoint. The addition of gemtuzumab ozogamicin did not increase the proportion of patients achieving complete remission with or without complete peripheral count recovery (odds ratio OR 0·91, 95% CI 0·77–1·07; p=0·3). However, the addition of gemtuzumab ozogamicin significantly reduced the risk of relapse (OR 0·81, 0·73–0·90; p=0·0001), and improved overall survival at 5 years (OR 0·90, 0·82–0·98; p=0·01). At 6 years, the absolute survival benefit was especially apparent in patients with favourable cytogenetic characteristics (20·7%; OR 0·47, 0·31–0·73; p=0·0006), but was also seen in those with intermediate characteristics (5·7%; OR 0·84, 0·75–0·95; p=0·005). Patients with adverse cytogenetic characteristics did not benefit (2·2%; OR 0·99, 0·83–1·18; p=0·9). Doses of 3 mg/m2 were associated with fewer early deaths than doses of 6 mg/m2 , with equal efficacy. Interpretation Gemtuzumab ozogamicin can be safely added to conventional induction therapy and provides a significant survival benefit for patients without adverse cytogenetic characteristics. These data suggest that the use of gemtuzumab ozogamicin should be reassessed and its licence status might need to be reviewed. Funding None.
Summary Background Chromosomal abnormalities in childhood acute lymphoblastic leukaemia are well established disease markers and indicators of outcomes. However, the long-term prognosis and ...independent prognostic effect of some abnormalities has been questioned. Also, little is known about the association between cytogenetics and the characteristics of relapse (eg, time and site of relapse) that are known to predict outcome after relapse. Methods We analysed cytogenetic data from 1725 children with B-cell precursor acute lymphoblastic leukaemia who were included in the UK Medical Research Council ALL97/99 study and followed up for a median time of 8·2 years. Univariate and multivariate analysis were done to examine risk of relapse, event-free survival, and overall survival associated with 21 chromosomal abnormalities and three cytogenetic risk groups constructed from these data. Findings Two chromosomal abnormalities were associated with a significantly better outcome ( ETV6–RUNX1 , hazard ratio HR 0·51, 95% CI 0·38–0·70 and high hyperdiploidy, 0·60, 0·47–0·78), whereas five abnormalities were associated with an increased risk of relapse (intrachromosomal amplification of chromosome 21 iAMP21, 6·04, 3·90–9·35; t(9;22), 3·55, 2·21–5·72; MLL translocations, 2·98, 1·71–5·20; abnormal 17p, 2·09, 1·30–3·37; and loss of 13q, 1·87, 1·09–3·20). Multivariate analysis incorporating age, white-cell count, and treatment parameters showed that six cytogenetic abnormalities ( ETV6–RUNX1 , high hyperdiploidy, iAMP21, t(9;22), loss of 13q, and abnormal 17p) retained their significance for effect on relapse risk. Based on these data, patients were classified into good, intermediate, and poor cytogenetic risk groups. Slow early treatment response correlated with cytogenetic risk group: 34 of 460 (7%) in the good-risk group, 22 of 211 (10%) in the intermediate-risk group, and 27 of 95 (28%) in the poor-risk group had a slow response (p<0·0001). Additionally, the proportion of patients with a very early (<18 months) relapse varied by cytogenetic risk group: eight of 129 (6%) patients in the good-risk group had a very early relapse, compared with 24 of 98 (24%) in the intermediate-risk group, and 37 of 82 (45%) in the poor-risk group (p<0·0001). However, there was no difference in the site of relapse by cytogenetic risk group. Interpretation Individual chromosomal abnormalities are strong independent indicators of outcome, especially risk of relapse. Diagnostic cytogenetics identifies patients with a higher rate of relapse and those who are likely to have a high-risk relapse. Funding Leukaemia and Lymphoma Research (LLR).