Population Pharmacokinetics of Inotuzumab Ozogamicin in Pediatric Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia: Results of Study ITCC-059.

BACKGROUND AND OBJECTIVE: Inotuzumab ozogamicin is an antibody-drug conjugate approved for treating relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in adults. Pediatric pharmacokinetic data of inotuzumab ozogamicin are lacking. This study is the first to examine the population pharmacokinetics of inotuzumab ozogamicin in pediatric patients with relapsed/refractory BCP-ALL. METHODS: From 531 adult patients with B-cell non-Hodgkin's lymphoma, 234 adult patients with BCP-ALL, and 53 pediatric patients with BCP-ALL, 8924 inotuzumab ozogamicin serum concentrations were analyzed using non-linear mixed-effects modeling. A published adult inotuzumab ozogamicin population-pharmacokinetic model, a two-compartment model with linear and time-dependent clearance, was adapted to describe the pediatric data. RESULTS: Modifications in this analysis, compared to the published adult model, included: (i) re-estimating pharmacokinetic parameters and covariate effects; (ii) modifying covariate representation; and (iii) introducing relevant pediatric covariate effects (age on the decay coefficient of time-dependent clearance and ALL effect (disease type and/or different bioanalytical analysis methods) on initial values of time-dependent clearance). For patients with relapsed/refractory BCP-ALL, increasing age was associated with a decreasing decay coefficient of time-dependent clearance, reflecting that the target-mediated drug clearance declines more rapidly in children. In pediatric BCP-ALL, the median [interquartile range] cumulative area under the concentration-time curve was significantly higher among responders (n = 42) versus non-responders (n = 10) at the end of the first cycle (26.1 [18.9-35.0] vs 10.1 [9.19-16.1], × 103 ng*h/mL, p < 0.001). From simulations performed at the recommended pediatric phase II dose, inotuzumab ozogamicin exposure reached a similar level as observed in responding pediatric trial participants. CONCLUSIONS: The pharmacokinetic profile of inotuzumab ozogamicin in pediatric patients with relapsed/refractory BCP-ALL was well described in this study. No dose adjustment is required clinically for pediatric patients with BCP-ALL based on the simulated inotuzumab ozogamicin exposure at the recommended pediatric phase II dose, promising efficacy and acceptable tolerability.

Inotuzumab ozogamicin as single agent in pediatric patients with relapsed and refractory acute lymphoblastic leukemia: results from a phase II trial.

Inotuzumab Ozogamicin is a CD22-directed antibody conjugated to calicheamicin, approved in adults with relapsed or refractory (R/R) B cell acute lymphoblastic leukemia (BCP-ALL). Patients aged 1-18 years, with R/R CD22 + BCP-ALL were treated at the RP2D of 1.8 mg/m2. Using a single-stage design, with an overall response rate (ORR) ≤ 30% defined as not promissing and ORR > 55% as expected, 25 patients needed to be recruited to achieve 80% power at 0.05 significance level. Thirty-two patients were enrolled, 28 were treated, 27 were evaluable for response. The estimated ORR was 81.5% (95%CI: 61.9-93.7%), and 81.8% (18/22) of the responding subjects were minimal residual disease (MRD) negative. The study met its primary endpoint. Median follow up of survivors was 16 months (IQR: 14.49-20.07). One year Event Free Survival was 36.7% (95% CI: 22.2-60.4%), and Overall Survival was 55.1% (95% CI: 39.1-77.7%). Eighteen patients received consolidation (with HSCT and/or CAR T-cells therapy). Sinusoidal obstructive syndrome (SOS) occurred in seven patients. MRD negativity seemed correlated to calicheamicin sensitivity in vitro, but not to CD22 surface expression, saturation, or internalization. InO was effective in this population. The most relevant risk was the occurrence of SOS, particularly when InO treatment was followed by HSCT.

Blinatumomab in pediatric relapsed/refractory B-cell acute lymphoblastic leukemia: RIALTO expanded access study final analysis.

The safety and efficacy of blinatumomab, a CD3/CD19-directed bispecific molecule, were examined in an open-label, single-arm, expanded access study (RIALTO). Children (>28 days and <18 years) with CD19+ relapsed/refractory B-cell precursor acute lymphoblastic leukemia (R/R B-ALL) received up to 5 cycles of blinatumomab by continuous infusion (cycle: 4 weeks on/2 weeks off). The primary end point was incidence of adverse events. Secondary end points included complete response (CR) and measurable residual disease (MRD) response within the first 2 cycles and relapse-free survival (RFS), overall survival (OS), and allogeneic hematopoietic stem cell transplant (alloHSCT) after treatment. At final data cutoff (10 January 2020), 110 patients were enrolled (median age, 8.5 years; 88% had ≥5% baseline blasts). A low incidence of grade 3 or 4 cytokine release syndrome (n = 2; 1.8%) and neurologic events (n = 4; 3.6%) was reported; no blinatumomab-related fatal adverse events were recorded. The probability of response was not affected by the presence of cytogenetic/molecular abnormalities. Median OS was 14.6 months (95% confidence interval [CI]: 11.0-not estimable) and was significantly better for MRD responders vs MRD nonresponders (not estimable vs 9.3; hazard ratio, 0.18; 95% CI: 0.08-0.39). Of patients achieving CR after 2 cycles, 73.5% (95% CI: 61.4%-83.5%) proceeded to alloHSCT. One-year OS probability was higher for patients who received alloHSCT vs without alloHSCT after blinatumomab (87% vs 29%). These findings support the use of blinatumomab as a safe and efficacious treatment of pediatric R/R B-ALL. This trial was registered at www.clinicaltrials.gov as #NCT02187354.

Other (Non-CNS/Testicular) Extramedullary Localizations of Childhood Relapsed Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma-A Report from the ALL-REZ Study Group.

Children with other extramedullary relapse of acute lymphoblastic leukemia are currently poorly characterized. We aim to assess the prevalence and the clinical, therapeutic and prognostic features of extramedullary localizations other than central nervous system or testis in children with relapse of acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) treated on a relapsed ALL protocol. PATIENTS AND METHODS: Patients with relapse of ALL and LBL, treated according to the multicentric ALL-REZ BFM trials between 1983 and 2015, were analyzed for other extramedullary relapse (OEMR) of the disease regarding clinical features, treatment and outcome. Local treatment/irradiation has been recommended on an individual basis and performed only in a minority of patients. RESULTS: A total of 132 out of 2323 (5.6%) patients with ALL relapse presented with an OEMR (combined bone marrow relapse n = 78; isolated extramedullary relapse n = 54). Compared to the non-OEMR group, patients with OEMR had a higher rate of T-immunophenotype (p < 0.001), a higher rate of LBL (p < 0.001) and a significantly different distribution of time to relapse, i.e., more very early and late relapses compared to the non-OEMR group (p = 0.01). Ten-year probabilities of event-free survival (pEFS) and overall survival (pOS) in non-OEMR vs. OEMR were 0.38 ± 0.01 and 0.32 ± 0.04 (p = 0.0204) vs. 0.45 ± 0.01 and 0.37 ± 0.04 (p = 0.0112), respectively. OEMRs have been classified into five subgroups according to the main affected compartment: lymphatic organs (n = 32, 10y-pEFS 0.50 ± 0.09), mediastinum (n = 35, 10y-pEFS 0.11 ± 0.05), bone (n = 12, 0.17 ± 0.11), skin and glands (n = 21, 0.32 ± 0.11) and other localizations (n = 32, 0.41 ± 0.09). Patients with OEMR and T-lineage ALL/LBL showed a significantly worse 10y-pEFS (0.15 ± 0.04) than those with B-Precursor-ALL (0.49 ± 0.06, p < 0.001). Stratified into standard risk (SR) and high risk (HR) groups, pEFS and pOS of OEMR subgroups were in the expected range whereas the mediastinal subgroup had a significantly worse outcome. Subsequent relapses involved more frequently the bone marrow (58.4%) than isolated extramedullary compartments (41.7%). In multivariate Cox regression, OEMR confers an independent prognostic factor for inferior pEFS and pOS. CONCLUSION: OEMR is adversely related to prognosis. However, the established risk classification can be applied for all subgroups except mediastinal relapses requiring treatment intensification. Generally, isolated OEMR of T-cell-origin needs an intensified treatment including allogeneic stem cell transplantation (HSCT) as a curative approach independent from time to relapse. Local therapy such as surgery and irradiation may be of benefit in selected cases. The indication needs to be clarified in further investigations.

Risk factors and outcomes in children with high-risk B-cell precursor and T-cell relapsed acute lymphoblastic leukaemia: combined analysis of ALLR3 and ALL-REZ BFM 2002 clinical trials.

AIM: Outcomes of children with high-risk (HR) relapsed acute lymphoblastic leukaemia (ALL) (N = 393), recruited to ALLR3 and ALL-REZ BFM 2002 trials, were analysed. Minimal residual disease (MRD) was assessed after induction and at predetermined time points until haematopoietic stem cell transplantation (SCT). METHODS: Genetic analyses included karyotype, copy-number alterations and mutation analyses. Ten-year survivals were analysed using Kaplan-Meier and Cox models for multivariable analyses. RESULTS: Outcomes of patients were comparable in ALLR3 and ALL-REZ BFM 2002. The event-free survival of B-cell precursor (BCP) and T-cell ALL (T-ALL) was 22.6% and 26.2% (P = 0.94), respectively, and the overall survival (OS) was 32.6% and 28.2% (P = 0.11), respectively. Induction failures (38%) were associated with deletions of NR3C1 (P = 0.002) and BTG1 (P = 0.03) in BCP-ALL. The disease-free survival (DFS) and OS in patients with good vs poor MRD responses were 57.4% vs 22.6% (P < 0.0001) and 57.8% vs 32.0% (P = 0.0004), respectively. For BCP- and T-ALL, the post-SCT DFS and OS were 42.1% and 56.8% (P = 0.26) and 51.6% and 55.4% (P = 0.67), respectively. The cumulative incidences of post-SCT relapse for BCP- and T-ALL were 36.9% and 17.8% (P = 0.012) and of death were 10.7% and 25.5% (P = 0.013), respectively. Determinants of outcomes after SCT were acute graft versus host disease, pre-SCT MRD (≥10-3), HR cytogenetics and TP53 alterations in BCP-ALL. CONCLUSION: Improvements in outcomes for HR ALL relapses require novel compounds in induction therapy to improve remission rates and immune targeted therapy after induction to maintain remission after SCT. TRIAL REGISTRATION: ALLR3: NCT00967057; ALL REZ-BFM 2002: NCT00114348.

A phase 1 study of inotuzumab ozogamicin in pediatric relapsed/refractory acute lymphoblastic leukemia (ITCC-059 study).

This phase 1 study investigated the recommended phase 2 dose (RP2D) of inotuzumab ozogamicin (InO), a CD22-directed antibody-drug conjugate, in pediatric patients with multiple relapsed/refractory (R/R) CD22+ acute lymphoblastic leukemia (ALL). Patients (age ≥1 year or <18 years) received 3 doses of InO (days 1, 8, and 15) per course. Dose escalation was based on dose-limiting toxicities (DLTs) during course 1. Dose level 1 (DL1) was 1.4 mg/m2 (0.6, 0.4, 0.4 mg/m2) and DL2 was 1.8 mg/m2 (0.8, 0.5, 0.5 mg/m2). Secondary end points included safety, antileukemic activity, and pharmacokinetics. Twenty-five patients (23 evaluable for DLTs) were enrolled. In course 1, the first cohort had 1 of 6 (DL1) and 2 of 5 (DL2) patients who experienced DLTs; subsequent review considered DL2 DLTs to be non-dose-limiting. Dose was de-escalated to DL1 while awaiting protocol amendment to re-evaluate DL2 in a second cohort, in which 0 of 6 (DL1) and 1 of 6 (DL2) patients had a DLT. Twenty-three patients experienced grade 3 to 4 adverse events; hepatic sinusoidal obstruction syndrome was reported in 2 patients after subsequent chemotherapy. Overall response rate after course 1 was 80% (95% confidence interval [CI], 59% to 93%) (20 of 25 patients; DL1: 75% [95% CI, 43% to 95%], DL2: 85% [95% CI, 55% to 98%]). Of the responders, 84% (95% CI, 60% to 97%) achieved minimal residual disease (MRD)-negative complete response, and 12-month overall survival was 40% (95% CI, 25% to 66%). Nine patients received hematopoietic stem cell transplantation or chimeric antigen receptor T cells after InO. InO median maximum concentrations were comparable to simulated adult concentrations. InO was well tolerated, demonstrating antileukemic activity in heavily pretreated children with CD22+ R/R ALL. RP2D was established as 1.8 mg/m2 per course, as in adults. This trial was registered at https://www.clinicaltrialsregister.eu as EUDRA-CT 2016-000227-71.

Improving Stratification for Children With Late Bone Marrow B-Cell Acute Lymphoblastic Leukemia Relapses With Refined Response Classification and Integration of Genetics.

PURPOSE: Minimal residual disease (MRD) helps to accurately assess when children with late bone marrow relapses of B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) will benefit from allogeneic hematopoietic stem-cell transplantation (allo-HSCT). More detailed dissection of MRD response heterogeneity and the specific genetic aberrations could improve current practice. PATIENTS AND METHODS: MRD was assessed after induction treatment and at different times during relapse treatment until allo-HSCT (indicated in poor responders to induction; MRD ≥ 10-3) for patients being treated for late BCP-ALL bone marrow relapses (n = 413; median follow-up, 9.4 years) in the ALL-REZ BFM 2002 trial/registry (ClinicalTrials.gov identifier: NCT00114348). RESULTS: Patients with both good (MRD < 10-3) and poor responses to induction treatment reached excellent event-free survival (EFS; 72% v 65%) and overall survival (OS; 82% v 74%). Patients with MRD of 10-2 or greater after induction had reduced EFS (56%), and their MRD persisted until allo-HSCT more frequently than it did in patients with MRD of 10-3 or greater to less than 10-2 (P = .037). Patients with 25% or more leukemic blasts after induction (early nonresponders) had the poorest prognosis (EFS, 22%). Interestingly, patients with MRD of 10-3 or greater before allo-HSCT (late nonresponders) still had an EFS of 50% and OS of 63%, which in principle justifies allo-HSCT in these patients. From a panel of selected candidate genes, TP53 alterations (frequency, 8%) were the only genetic alteration with independent prognostic value in any MRD-based response subgroup. CONCLUSION: After induction treatment, MRD-based treatment stratification resulted in excellent survival in patients with late relapsed BCP-ALL. Prognosis could be further improved in very poor responders by intensifying treatment directly after induction. TP53 alterations can be defined as a novel genetic high-risk marker in all MRD response groups in late relapsed BCP-ALL. Here we identified early and late nonresponders to be considered as events in future trials.

Aneuploidy in children with relapsed B-cell precursor acute lymphoblastic leukaemia: clinical importance of detecting a hypodiploid origin of relapse.

Aneuploidy is common in paediatric B-cell precursor acute lymphoblastic leukaemia (ALL). Specific subgroups, such as high hyperdiploidy (>50 chromosomes or DNA Index ≥1·16) and hypodiploidy (<45 chromosomes), predict outcome of patients after primary treatment. Whether aneuploidy has a prognostic value for relapsed disease is yet to be determined. Using DNA index and centromere screening by multiplex ligation-dependent probe amplification, we investigated aneuploidy in 413 children treated for first relapse of B-cell precursor ALL according to the ALL-REZ BFM 2002 protocol. Ten-year event-free survival of patients with high hyperdiploid relapses approached 70%, whereas it was only 40% in low hyperdiploid relapses. Three patients with apparent hyperdiploid relapse had TP53 mutations. In these cases, array-based allelotyping revealed a hypodiploid origin with absence of the hypodiploid founder clone (masked hypodiploidy). Collectively, patients with evident or masked hypodiploid relapses showed an extremely low event-free survival rate of 9%. Importantly, the current relapse risk stratification did not identify cases with masked hypodiploidy as high-risk patients, due to their favourable clinical presentation. In multivariate analysis, hypodiploidy proved to be an independent prognostic factor. This finding supports stratification of relapses with hypodiploid origin into high-risk arms in future trials or allocation of patients to alternative treatment approaches.

Neurotoxic side effects in children with refractory or relapsed T-cell malignancies treated with nelarabine based therapy.

The prognosis in children with refractory or relapsed (r/r) T-cell acute lymphoblastic leukaemia (T-ALL) or lymphoblastic lymphoma (T-LBL) is poor. Nelarabine (Ara-G) has successfully been used as salvage therapy in these children, but has been associated with significant, even fatal, neurotoxicities. We retrospectively analysed 52 patients with r/r T-ALL/T-LBL aged ≤19 years who were treated with Ara-G alone (n = 25) or in combination with cyclophosphamide and etoposide (n = 27). The majority of patients (45/52) received 1-2 cycles of Ara-G. Seventeen patients (32·7%) had refractory disease, 28 (53·8%) were in first relapse and 7 (13·5%) were in second relapse. A response to Ara-G was achieved in 20 patients and 15 (28·8%) were in remission at last follow-up. Twelve patients (23·1%) had neurotoxic adverse effects (neuro-AE) of any grade, of whom 7 (13·5%) developed neurotoxicity ≥ grade III. The most frequent neuro-AEs were peripheral motor neuropathy (19·2%), peripheral sensory neuropathy (11·5%) and seizures (9·6%). Three patients died of central neuro-AE after 1-2 cycles of combination therapy. Patients with neurotoxicity were significantly older (median 15·17 years) than those without (10·34 years, P = 0·017). No differences were observed between mono- and combination therapy concerning outcome and neuro-AE. The incidence of neuro-AE was not associated with concurrent intrathecal therapy or prior central nervous system irradiation.