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PD-1 Inhibition Enhances Blinatumomab Response in a UCB/PDX Model of Relapsed Pediatric B-Cell Acute Lymphoblastic Leukemia.

ABSTRACT: Immune therapies such as blinatumomab, CD19-directed bispecific CD3 T-cell Engager (BiTE), have resulted in significant improvements in outcomes for relapsed B-cell acute lymphoblastic leukemia (B-ALL). However, up to half of blinatumomab treated patients do not respond completely or relapse after therapy. As a result, there is a need to identify potential strategies to improve the efficacy of BiTE therapy. The anti-PD-1 antibody pembrolizumab has been shown to successfully activate T cells against a wide range of cancer types. Here, we tested the ability of umbilical cord blood (UCB) reconstituted mice to respond to blinatumomab therapy with or without concurrent pembrolizumab treatment. Humanized mice were engrafted with patient-derived xenograft (PDX) cells derived from pediatric and adolescent/young adult (AYA) B-ALL patients who had either failed to achieve remission with negative minimum residual disease (MRD negative) or experienced a relapse. Mock-treated humanized mice engrafted with PDX cells efficiently developed overt disease within 30 days of engraftment of B-ALL. However, single agent therapy with either blinatumomab or pembrolizumab reduced disease burden in engrafted mice, with some mice observed to be MRD negative after the 28-day treatment course. Combination therapy significantly improved the percentage of MRD negative mice and improved long-term survival and cure rates as compared to mice that were given blinatumomab alone. Importantly, no benefits were observed in treated mice that lacked human immune cell reconstitution. These results indicate that UCB-humanized NRGS mice develop activatable immune function, and UCB-humanized PDX leukemia models can be used in preclinical studies to evaluate specificity, efficacy, and cooperativity of immune therapies in B-ALL.

SUBMITTER: Wunderlich M

PROVIDER: S-EPMC8076590 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Adults with relapsed/refractory B-acute lymphoblastic leukemia (ALL) have a complete remission (CR) rate of 20-45% and median overall survival of 3-9 months, depending on the duration of the first remission and number of lines of salvage therapy. Allogeneic hematopoietic stem cell transplantation (alloHSCT) is the only curative option for adult patients with relapsed/refractory ALL, and achievement of CR is a crucial step before alloHSCT. Blinatumomab is a bispecific T-cell engager (BiTE®) antibody construct with dual specificity for CD19 and CD3, simultaneously binding CD3-positive cytotoxic T cells and CD19-positive B cells, resulting in T-cell-mediated serial lysis of normal and malignant B cells. It recently gained accelerated approval by the US Food and Drug Administration (FDA) for the treatment of relapsed/refractory Philadelphia chromosome-negative ALL, based on a large phase II trial of 189 adults with relapsed/refractory B-ALL, which showed a CR/CRh (CR with partial hematologic recovery) of 43% after two cycles of treatment. Toxicities include cytokine-release syndrome (CRS) and neurologic events (encephalopathy, aphasia, and seizure). CRS can be alleviated by step-up dosing and dexamethasone, without affecting the cytotoxic effect of blinatumomab. The cause of neurologic toxicity is unclear but is also observed with other T-cell therapies and may relate to variable expression of CD19 within the brain. This review encompasses the preclinical rationale of using the BITE® class of compounds (blinatumomab being the only one that is FDA approved), with clinical data using blinatumomab in the relapsed/refractory setting (pediatrics and adults), the minimal residual disease setting (adults), as well as Philadelphia chromosome-positive ALL. The review also examines the main adverse events: their prevention, recognition, and management; possible mechanisms of resistance; causes of relapse. It also summarizes future trials evaluating the drug earlier in the treatment course to improve activity.

Project description:INTRODUCTION:No head-to-head studies have compared inotuzumab ozogamicin (InO) and blinatumomab (Blina) for the treatment of adults with relapsed or refractory B cell precursor acute lymphoblastic leukemia (ALL). Indirect treatment comparisons (ITCs), namely network meta-analysis (NMA), anchored matching-adjusted indirect comparison (MAIC), and simulated treatment comparison (STC), were conducted to compare the relative efficacy of these therapies. METHODS:Patient-level data from a study that evaluated InO with standard of care (SoC) chemotherapy (INO-VATE-ALL) and published data from a study that evaluated Blina with SoC chemotherapy (TOWER) were used in the analyses. Endpoints evaluated included remission rate defined as complete remission or complete remission with incomplete hematologic recovery (CR/CRi), hematopoietic stem cell transplantation (HSCT), overall survival (OS), and event-free survival (EFS). For each outcome, treatment-effect modifiers were adjusted for in the anchored MAIC and STC analyses. RESULTS:Analyses showed statistically significant higher rates of remission and HSCT with InO compared to Blina irrespective of the ITC method used or measure of the effect (i.e., odds ratio [OR] or rate difference). The treatment effects derived from the MAIC and STC analyses were consistent and stronger than those estimated from the NMA. A trend favoring InO was detected for EFS. The ITC results for OS suggest no difference between InO and Blina. CONCLUSION:Results from these ITCs indicated a statistically significant advantage for InO over Blina for rates of remission and HSCT in adults with relapsed or refractory B cell precursor ALL. It was not possible to fully adjust for all treatment-effect modifiers, and the similarity in chemotherapy regimens used in the SoC comparator arms of the INO-VATE-ALL and TOWER studies is worthy of further exploration. Both studies, however, used chemotherapy regimens that have a low response rate; therefore, no significant differences in efficacy outcomes are expected between SoC arms. FUNDING:Pfizer Inc, New York, NY. Plain language summary available for this article.

Project description:BackgroundBlinatumomab is a CD19 BiTE (bispecific T-cell engager) immuno-oncology therapy that mediates the lysis of cells expressing CD19.MethodsA pooled analysis of long-term follow-up data from 2 phase 2 studies that evaluated blinatumomab in heavily pretreated adults with Philadelphia chromosome-negative, relapsed/refractory B-cell precursor acute lymphoblastic leukemia was conducted.ResultsA total of 259 patients were included in the analysis. The median overall survival (OS) among all patients, regardless of response, was 7.5 months (95% confidence interval [CI], 5.5-8.5 months); the median follow-up time for OS was 36.0 months (range, 0.3-60.8 months). The median relapse-free survival (RFS) among patients who achieved a complete remission (CR) or complete remission with partial hematologic recovery (CRh) in the first 2 cycles (n = 123) was 7.7 months (95% CI, 6.2-10.0 months); the median follow-up time for RFS was 35.0 months (range, 9.5-59.5 months). OS and RFS plateaued with 3-year rates of 17.7% and 23.4%, respectively. The cumulative incidence function of the time to relapse, with death not due to relapse considered a competing risk, for patients who achieved a CR/CRh within 2 cycles of treatment also plateaued with a 3-year relapse rate of 59.3%. For patients who achieved a CR/CRh with blinatumomab followed by allogeneic hematopoietic stem cell transplantation while in continuous CR, the median OS was 18.1 months (95% CI, 10.3-30.0 months) with a 3-year survival rate of 37.2%.ConclusionsThese data suggest that long-term survival is possible after blinatumomab therapy.Lay summaryImmuno-oncology therapies such as blinatumomab activate the patient's own immune system to kill cancer cells. This study combined follow-up data from 2 blinatumomab-related clinical trials to evaluate long-term survival in patients with relapsed and/or refractory B-cell precursor acute lymphoblastic leukemia at high risk for unfavorable outcomes. Among patients who achieved a deep response with blinatumomab, one-third lived 3 years or longer. These findings suggest that long-term survival is possible after treatment with blinatumomab.

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PD-1 Inhibition Enhances Blinatumomab Response in a UCB/PDX Model of Relapsed Pediatric B-Cell Acute Lymphoblastic Leukemia.

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