Gemtuzumab ozogamicin (GO) as monotherapy and in combination with hypomethylation agents in the treatment of acute myeloid leukemia: a systematic meta-analysis.

OBJECTIVES: To explore whether the addition of HMA to GO could bring additional clinical benefits to AML patients. BACKGROUND: Several studies have shown the HMA plus GO combination showed exciting results. However, the comparison of the clinical efficacy and safety profile of this combination with GO monotherapy has not been witnessed. METHODS: We performed a systematic review and meta-analysis of 18 clinical trials regarding the mono-GO therapy alone or the HMA + GO combination. The random-effect model or fixed-effect model was applied to the study based on heterogeneity. RESULTS: Pooled data of HMA + GO combination are more effective than mono-GO therapy among the unfit acute myeloid leukemia (AML) patients, based on the evaluation of overall response rate (ORR) (HMA + GO vs. mono-GO, 48% vs. 25%), composite complete remission (CRc) (HMA + GO vs. mono-GO, 42% vs. 25%). But pooled data of CRc and ORR showed no notable difference among R/R AML patients. Safety profiles have demonstrated that the HMA + GO combination was tolerable, considering the relatively low toxicities. CONCLUSION: HMA + GO combination, more effective and better tolerated than mono-GO therapy should be recommended to treat unfit AML patients instead of R/R AML patients.

Outcomes of Adult Acute Myeloid Leukemia Treated With Gemtuzumab-Ozogamicin: Cue To Optimized Chemotherapy Backbone.

BACKGROUND: The optimal approach to combine gemtuzumab-ozogamicin (GO) with various chemotherapy backbones and other newer agents safely remains to be determined. MATERIALS AND METHODS: We performed a retrospective analysis of the safety and outcomes of adult patients with newly diagnosed acute myeloid leukemia (AML) treated with GO with intensified versus standard anthracycline doses (daunorubicin dose 90 mg/m2 vs 60 mg/m2) ± FLT3 inhibitors. The χ2 test and Mann-Whitney U test were used to compare categorical and continuous data. Survival estimates were calculated by Kaplan-Meier method and survival comparisons made using log-rank test. RESULTS: We report a 97% overall response rate in 34 patients with newly diagnosed AML with a median age of 54 years (19-75 years) treated with GO and standard induction. The 11 patients (100%) receiving GO plus daunorubicin dose 90 mg/m2 as part of 7 + 3 induction achieved complete response versus 91% (20/22) complete response in the standard daunorubicin dose group (P = NS). No increased toxicity was noted with the higher daunorubicin dose or when GO and 7 + 3 were combined with FLT3 inhibitors in 3 younger patients (<60 years). Two older patients treated with GO+7 + 3 and FLT3i experienced grade 3 or higher cardiotoxicity. We observed a longer estimated event-free survival for patients with newly diagnosed AML in our cohort (median, 24 months; 95% confidence interval, 17.2 to not reached) compared with historical data. CONCLUSION: We demonstrate that anthracycline dose intensification with GO may offer higher response rates without increased toxicity in younger patients presenting with de novo AML across European Leukemia Net risk categories.

Molecular classification and prognosis in younger adults with acute myeloid leukemia and intermediate-risk cytogenetics treated or not by gemtuzumab ozogamycin: Final results of the GOELAMS/FILO acute myeloid leukemia 2006-intermediate-risk trial.

In this randomized phase 3 study, the FILO group tested whether the addition of 6 mg/m2 of gemtuzumab ozogamycin (GO) to standard chemotherapy could improve outcome of younger patients with de novo acute myeloid leukemia (AML) and intermediate-risk cytogenetics. GO arm was prematurely closed after 254 inclusions because of toxicity. A similar complete remission rate was observed in both arms. Neither event-free survival nor overall survival were improved by GO in younger AML patients (<60 years) ineligible for allogeneic stem-cell transplantation. (P = .086; P = .149, respectively). Using unsupervised hierarchical clustering based on mutational analysis of seven genes (NPM1, FLT3-ITD, CEBPA, DNMT3A, IDH1, IDH2, and ASXL1), six clusters of patients with significant different outcome were identified. Five clusters were based on FLT3-ITD, NPM1, and CEBPA mutations as well as epigenetic modifiers (DNMT3A, IDH1/2, ASXL1), whereas the last cluster, representing 25% of patients, had no mutation and intermediate risk. One cluster isolated FLT3-ITD mutations with higher allelic ratio and a very poor outcome. The addition of GO had no impact in these molecular clusters. Although not conclusive for GO impact in AML patients <60 years, this study provides a molecular classification that distinguishes six AML clusters influencing prognosis in younger AML patients with intermediate-risk cytogenetic.

Gemtuzumab Ozogamicin Combined With Intensive Chemotherapy in Patients With Acute Myeloid Leukemia Relapsing After Allogenic Stem Cell Transplantation.

BACKGROUND: More than one-third of patients with acute myeloid leukemia (AML) will relapse after allogenic hematopoietic cell transplant (allo-HCT). The main challenge is to overcome disease resistance to achieve a new complete remission while avoiding excessive toxicity. Gemtuzumab ozogamicin (GO), a conjugate of calicheamicin linked to the humanized monoclonal anti-CD33 antibody, has been used for refractory or relapsed AML with promising response rates, but liver toxicity of GO has long been considered a limiting factor. PATIENTS AND METHODS: We included 18 consecutive patients with AML relapsing after a first allo-HCT and treated with fractioned GO (fGO) and intensive chemotherapy. The median age was 40 years (range, 18-65). RESULTS: The overall response rate was 72% (13/18), including 7 complete remissions. No death was attributed to treatment toxicity. The main liver toxicity was transient and consisted of transaminase level elevation and hyperbilirubinemia. No cases of veno-occlusive disease were observed after the GO treatment. From the time of salvage treatment initiation, 1- and 2-year OS rates were 54% (95% confidence interval, 28%-74%) and 42% (95% confidence interval, 19%-63%), respectively. CONCLUSIONS: Our study suggests the feasibility, efficacy, and safety of an fGO-based salvage regimen combined with intensive chemotherapy in patients with CD33+ AML in the case of early relapse after an allo-HCT.

Recent drug approvals for newly diagnosed acute myeloid leukemia: gifts or a Trojan horse?

Since 2017 the US Food and Drug Administration (FDA) has approved glasdegib, venetoclax, ivosidenib, midostaurin, CPX- 351, and gemtuzumab ozogamicin (GO) to treat persons with newly diagnosed acute myeloid leukemia. The European Medicines Agency (EMA) has done likewise for midostaurin, CPX-351, and GO. While increasing options for persons, particularly older ones, for whom current therapy is unsatisfactory, or simply not given, these approvals raise several concerns. Although the venetoclax and glasdegib approvals were for persons considered "unfit" for intensive induction, the criteria for fitness were not well defined (age ≥75 per se being insufficient) and are frequently subjective, making it likely that many subjects in the venetoclax and glasdegib registration trials were fit for intensive induction; for example, none had performance status 3-4. Fitness must be assessed together with the potential efficacy of a proposed therapy. We note the modest complete remission rates and durations in the venetoclax + hypomethylating agent trial. Although these formed the basis for FDA approval, it is unclear that better results might not have obtained with more intense induction, as several studies, with considerably longer-follow up, have suggested. Hence, we question the venetoclax (and glasdegib) approvals absent randomized comparisons with intense induction. Given the uncertain relation in older individuals between survival and complete remission (CR), much less responses less than CR, we are skeptical of the sole use of these responses in the ivosidenib and venetoclax approvals; we also question the use of survival, without event-free survival, in the glasdegib approval. Noting the midostaurin and CPX-351 approvals included populations not participating in the registration studies we suggest means to address this issue as well as those involving fitness, randomization, and endpoints.

MDSC targeting with Gemtuzumab ozogamicin restores T cell immunity and immunotherapy against cancers.

BACKGROUND: Targeting of MDSCs is a major clinical challenge in the era of immunotherapy. Antibodies which deplete MDSCs in murine models can reactivate T cell responses. In humans such approaches have not developed due to difficulties in identifying targets amenable to clinical translation. METHODS: RNA-sequencing of M-MDSCs and G-MDSCs from cancer patients was undertaken. Flow cytometry and immunohistochemistry of blood and tumours determined MDSC CD33 expression. MDSCs were treated with Gemtuzumab ozogamicin and internalisation kinetics, and cell death mechanisms determined by flow cytometry, confocal microscopy and electron microscopy. Effects on T cell proliferation and CAR-T cell anti-tumour cytotoxicity were identified in the presence of Gemtuzumab ozogamicin. FINDINGS: RNA-sequencing of human M-MDSCs and G-MDSCs identified transcriptomic differences, but that CD33 is a common surface marker. Flow cytometry indicated CD33 expression is higher on M-MDSCs, and CD33+ MDSCs are found in the blood and tumours regardless of cancer subtype. Treatment of human MDSCs leads to Gemtuzumab ozogamicin internalisation, increased p-ATM, and cell death; restoring T cell proliferation. Anti-GD2-/mesothelin-/EGFRvIII-CAR-T cell activity is enhanced in combination with the anti-MDSC effects of Gemtuzumab ozogamicin. INTERPRETATION: The study identifies that M-MDSCs and G-MDSCs are transcriptomically different but CD33 is a therapeutic target on peripheral and infiltrating MDSCs across cancer subtypes. The immunotoxin Gemtuzumab ozogamicin can deplete MDSCs providing a translational approach to reactivate T cell and CAR-T cell responses against multiple cancers. In the rare conditions of HLH/MAS gemtuzumab ozogamicin provides a novel anti-myeloid strategy. FUND: This work was supported by Cancer Research UK, CCLG, Treating Children with Cancer, and the alumni and donors to the University of Birmingham.

An mTORC1/2 dual inhibitor, AZD2014, acts as a lysosomal function activator and enhances gemtuzumab ozogamicin-induced apoptosis in primary human leukemia cells.

Gemtuzumab ozogamicin (GO), an anti-CD33 antibody linked to calicheamicin via an acid-labile linker, is the first antibody-drug conjugate (ADC). The acidic environment inside lysosomes of target cells is an important intracellular determinant of the cytocidal action of GO, as the linker is hydrolyzed under acidic conditions. However, lysosomal activity in acute myeloid leukemia (AML) blasts in GO therapy has been insufficiently evaluated. It has been suggested that lysosome activity is suppressed in AML due to hyperactivation of the phosphoinositide 3-kinase/Akt pathway. We therefore hypothesized that agents which activate lysosomal function would potentiate the cytotoxicity of GO. Here, we found that a clinically useful mTORC1/2 dual inhibitor, AZD2014, reduced pH in the acidic organelles, including lysosomes, as shown by increased LysoTracker fluorescent intensity, and synergistically enhanced the cytotoxic effect of GO in primary leukemia cells. GO-induced cytotoxicity appeared to be enhanced with the increase in lysosomal activity by AZD2014. These results indicate that AZD2014 activated lysosomal function in primary leukemia cells, which in turn enhanced the cytotoxicity of GO. Enhancement of lysosomal activity may represent a new therapeutic strategy in the treatment of GO and other ADCs, particularly in cases with low lysosomal activity.

Pharmacokinetic/Pharmacodynamic Modeling to Support the Re-approval of Gemtuzumab Ozogamicin.

Gemtuzumab ozogamicin (Mylotarg; Pfizer, New York, NY) was the first antibody-drug conjugate to be approved for CD33-positive acute myeloid leukemia (AML). However, it was voluntarily withdrawn from the US market due to lack of clinical benefit in the confirmatory phase III trial. In 2012, several investigator cooperative studies using a different dosing regimen showed efficacy, but pharmacokinetic (PK) data were not collected in these trials. Through simulation of expected concentrations for new dosing regimens, PK/pharmacodynamic modeling was able to support the safety and efficacy of these regimens. Significant exposure-response relationships were found for the attainment of complete remission with and without platelet recovery, attainment of blast-free status, the time course of myelosuppression, several grade ≥ 3 hepatic adverse events, and veno-occlusive disease. Gemtuzumab ozogamicin received full approval by the US Food and Drug Administration (FDA) in September 2017 for newly diagnosed and relapsed AML in adult patients and relapsed AML in pediatric patients aged 2-17 years.

FDA Approval: Gemtuzumab Ozogamicin for the Treatment of Adults with Newly Diagnosed CD33-Positive Acute Myeloid Leukemia.

On September 1, 2017, the FDA granted approval for gemtuzumab ozogamicin (Mylotarg; Pfizer Inc.) in combination with daunorubicin and cytarabine and as a monotherapy for the treatment of adult patients with newly diagnosed CD33-positive acute myeloid leukemia (AML). Gemtuzumab ozogamicin is a CD33-targeted antibody-drug conjugate joined to calicheamicin. Approval of gemtuzumab ozogamicin combination treatment was based on a randomized trial of 271 patients with newly diagnosed AML treated with daunorubicin and cytarabine with or without 3 mg/m2 fractionated gemtuzumab ozogamicin, which resulted in an event-free survival (EFS) of 13.6 months for gemtuzumab ozogamicin + daunorubicin and cytarabine and 8.8 months for daunorubicin and cytarabine alone [HR = 0.68 (95% confidence interval (CI), 0.51-0.91)]. Hemorrhage, prolonged thrombocytopenia, and veno-occlusive disease were serious toxicities that were more common in patients treated with gemtuzumab ozogamicin + daunorubicin and cytarabine. Approval of gemtuzumab ozogamicin monotherapy was based on a randomized trial of 237 patients with newly diagnosed AML treated without curative intent. Median overall survival (OS) was 4.9 months with gemtuzumab ozogamicin versus 3.6 months on best supportive care [HR = 0.69 (95% CI, 0.53-0.90)]. Adverse events were similar on both arms. Postapproval, several studies are required including evaluation of fractionated gemtuzumab ozogamicin pharmacokinetics, safety of combination gemtuzumab ozogamicin in the pediatric population, immunogenicity, and the effects of gemtuzumab ozogamicin on platelet function. Clin Cancer Res; 24(14); 3242-6. ©2018 AACR.