Tisagenlecleucel is a CD19 chimeric antigen receptor (CAR) T-cell therapy approved for treatment of pediatric and young adult patients with relapsed/refractory acute lymphoblastic leukemia (ALL) and adults with non-Hodgkin lymphoma (NHL). The initial experience with tisagenlecleucel in a real-world setting from a cellular therapy registry is presented here. As of January 2020, 511 patients were enrolled from 73 centers, and 410 patients had follow-up data reported (ALL, n = 255; NHL, n = 155), with a median follow-up of 13.4 and 11.9 months for ALL and NHL, respectively. Among patients with ALL, the initial complete remission (CR) rate was 85.5%. Twelve-month duration of response (DOR), event-free survival, and overall survival (OS) rates were 60.9%, 52.4%, and 77.2%, respectively. Among adults with NHL, the best overall response rate was 61.8%, including an initial CR rate of 39.5%. Six-month DOR, progression-free survival, and OS rates were 55.3%, 38.7%, and 70.7%, respectively. Grade ≥3 cytokine release syndrome and neurotoxicity were reported in 11.6% and 7.5% of all patients, respectively. Similar outcomes were observed in patients with in-specification and out-of-specification products as a result of viability <80% (range, 61% to 79%). This first report of tisagenlecleucel in the real-world setting demonstrates outcomes with similar efficacy and improved safety compared with those seen in the pivotal trials.

Astrocytomas account for the majority of malignant brain tumors diagnosed in both adult and pediatric patients. The therapies available to treat these neoplasms are limited, and the prognosis associated with high-grade lesions is extremely poor. Mer (MerTK) and Axl receptor tyrosine kinases (RTK) are expressed at abnormally high levels in a variety of malignancies, and these receptors are known to activate strong antiapoptotic signaling pathways that promote oncogenesis. In this study, we found that Mer and Axl mRNA transcript and protein expression were elevated in astrocytic patient samples and cell lines. shRNA-mediated knockdown of Mer and Axl RTK expression led to an increase in apoptosis in astrocytoma cells. Apoptotic signaling pathways including Akt and extracellular signal–regulated kinase 1/2, which have been shown to be activated in resistant astrocytomas, were downregulated with Mer and Axl inhibition whereas poly(ADP-ribose) poly-merase cleavage was increased. Furthermore, Mer and Axl shRNA knockdown led to a profound decrease of astrocytoma cell proliferation in soft agar and a significant increase in chemosensitivity in response to temozolomide, carboplatin, and vincristine treatment. Our results suggest Mer and Axl RTK inhibition as a novel method to improve apoptotic response and chemosensitivity in astrocytoma and provide support for these oncogenes as attractive biological targets for astrocytoma drug development.

Purpose: The Mer receptor tyrosine kinase, cloned from a B-lymphoblastoid library, is the mammalian orthologue of the chicken retroviral oncogene v-eyk and sends antiapoptotic and transforming signals when activated. To determine if Mer expression is ectopic in T-cell acute lymphoblastic leukemia (ALL) and potentially important in leukemogenesis, we analyzed Mer expression in normal human thymocytes and lymphocytes and in pediatric ALL patient samples. Experimental Design: Reverse transcription-PCR, flow cytometry, and immunohistochemistry were used to determine expression of Mer in sorted human thymocyte populations, lymphocytes, and lymphocytes activated by phytohemagglutinin or phorbol 12-myristate 13-acetate/ ionophore. Mer expression in 34 T-cell ALL (T-ALL) patient samples was evaluated by reverse transcription-PCR, and Mer protein expression in a separate cohort of 16 patient samples was assayed by flow cytometry and Western blot. Results: Mer expression was absent in normal thymocytes or lymphocytes, and in T cells activated with phytohemagglutinin or phorbol 12-myristate 13-acetate/ionophore. In contrast, Jurkat cells and T-ALL patient samples expressed unique 180 to 185 kDa Mer protein glycoforms. Substantial Mer RNA levels were principally observed in a subset of T-ALL patient samples that expressed B220 (P = 0.004) but lacked surface expression of CD3 (P = 0.02) and CD4 (P = 0.006), a phenotypic profile consistent with immature lymphoblasts. In addition, 8 of 16 T-ALL patient samples had Mer protein detected by flow cytometry and Western blot. Conclusions: Transforming Mer signals may contribute to T-cell leukemogenesis, and abnormal Mer expression may be a novel therapeutic target in pediatric ALL therapy.Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. The current 80% 5-year event-free survival rate is a product of national pediatric oncology cooperative group clinical trials that have optimized patient outcome. Future improvements will rely on a better understanding of the definition and pathogenesis of different ALL subtypes. Specifically, biologically targeted therapy against unique leukemia markers or signaling pathways is being tested in clinical trials and hopefully will complement current treatment regimens. In this study, we report a new potential biological marker in pediatric ALL.Mer was initially cloned by our group from a human B lymphoblastoid cDNA library, and Mer RNA transcript was also found to be expressed in T-cell ALL (T-ALL) cell lines (1). This was intriguing because Mer RNA was not detected in freshly isolated human (or mouse) T or B lymphocytes. Subsequent work has shown that Mer signaling, via activated Mer receptor tyrosine kinase domain, can be antiapoptotic (32D cells; ref.2), cytoskeletal regulatory, or frankly transforming [Ba/F3 pro-Blymphocytes (3) and NIH 3T3 fibroblasts (4)], depending on the cell type. The retrovirally transduced chicken orthologue v-eyk was also frankly transforming (5, 6). We now show that Mer expression is abs...