Miriam Kim

Pharmacoeconomic Implications of Lenalidomide Maintenance Therapy in Multiple Myeloma

We compared the three arms of the MM-015 randomized phase III clinical trial [melphalan and prednisone (MP), MP plus lenalidomide (MPR), and MPR plus lenalidomide maintenance (MPR-R)] to determine whether the addition of lenalidomide maintenance therapy for primary treatment of multiple myeloma is cost-effective. We used progression-free survival and adverse event data from the MM-015 study for the analysis. Two novel measures of cost-effectiveness termed the Average Cumulative Cost per Patient (ACCP) and the Average Cumulative Cost per Progression-Free Survivor (ACCPFS) were developed for the purpose of this analysis. The ACCP of MP was USD 18,218, compared to USD 167,862 for MPR and USD 309,173 for MPR-R. The ACCPFS was highest with MPR at USD 1,555,443, while MP was USD 313,592 and MPR-R was USD 690,111. MPR-R is superior to MPR in terms of preventing the first progression after initial therapy. However, the addition of lenalidomide to MP in the induction and also in the maintenance setting leads to significant costs.

Updates on the treatment of human epidermal growth factor receptor type 2-positive breast cancer.

Purpose of review To review the most recent developments in the treatment of human epidermal growth factor receptor type 2 (HER2)-positive breast cancer with novel HER2-targeting agents and combinations that have significantly improved clinical outcomes. Recent findings Since the approval of trastuzumab 15 years ago, the natural history of HER2-positive breast cancer has been altered with improvements in survival for both early and advanced disease with the addition of this agent to standard chemotherapy. The HER2 receptor pathway drives breast cancer growth and aggressiveness, and HER2-targeted agents can improve survival in early and advanced disease. In the advanced setting, two new drugs have been approved since 2012, pertuzumab and ado-trastuzumab emtansine (T-DM1), both of which improve survival without any reciprocal increase in toxicity. However, resistance almost always ensues, pointing to the need to understand the driving mechanisms and to biomarkers that will help individualize therapy and point to newer signal transduction and other modulators. Summary HER2-positive breast cancer represents a distinct subtype with more aggressive clinical characteristics. HER2-targeted therapies, usually in combination with chemotherapy, are the standard of care, improving the cure rate in early-stage breast cancer and lengthening survival in the advanced setting.

273. Genome Editing Using CRISPR-Cas9 to Increase the Therapeutic Index of Antigen-Specific Immunotherapy in Acute Myeloid Leukemia

Antigen-specific immunotherapy using chimeric antigen receptor (CAR) T cells or bispecific T cell engaging (BITE) antibodies directed against CD19 leads to elimination of malignant and normal B cells. These approaches have a broad therapeutic index in acute lymphoid leukemia (ALL) due to a combination of high anti-tumor activity and tolerability of prolonged B cell depletion. In contrast, in acute myeloid leukemia (AML) the absence of surface antigens specific to leukemia implies that potent myeloid-directed immunotherapy will eradicate normal as well as malignant cells, leading to protracted myeloablation and bone marrow failure, as has been shown in several preclinical studies of CD33 or CD123 directed CART cell therapy. We developed a novel approach to circumvent this problem by genetically modifying normal hematopoietic stem cells (HSCs) so that they do not express the antigen recognized by CART cells, thus generating normal myeloid progeny that is resistant to CART cell therapy.CD33 is expressed on the majority of AML as well on normal myeloid progenitors and its function is poorly characterized. We hypothesized that CD33 knockout HSCs and their myeloid progeny would develop normally yet be resistant to treatment with anti-CD33 CART cells (CART33). Electroporation of human CD34+ cells with Cas9 protein and in-vitro transcribed sgRNA generated deleterious mutations in the CD33 gene with 70-80% efficacy as measured by flow cytometry and DNA sequencing. Addition of a single-stranded oligonucleotide template with a short insertional mutation at the sgRNA cut site increased the knockout efficacy up to 90%. In vitro cytotoxicity assays showed CD33 KO HSC progeny are resistant to killing by CART33 compared to wild-type HSC controls (% live cells after CART33 co-culture: 60% vs. 18%, p=0.005). CD33 KO HSC progeny showed a similar growth and differentiation profile in Methocult semi-solid media compared to control cells that were electroporated with an unrelated sgRNA. The differentiated cells had normal neutrophil and macrophage morphology and immunophenotype. We also found that phagocytosis and cytokine secretion capabilities of the CD33 KO progeny were identical to WT control. NOD-SCID-g-/- (NSG) mice injected with CD33 KO HSCs showed normal engraftment with differentiation of both myeloid and lymphoid lineages. As expected, the percentage of CD33+ myeloid cells was lower in CD33 KO recipients than WT control (24% vs 63%, p<0.0001), yet the percentage of CD14+CD11b+ monocytes (45% vs 47%, p=0.77) and CD14-CD11b+ neutrophils (34% vs. 33%, p=0.87) were unaltered.This approach yields a potential strategy to treat AML with potent CD33-specific immunotherapy, followed by infusion of gene-modified CD33 KO HSCs, which will allow persistent antigen-specific immune attack along with reconstitution of effective hematopoiesis.

Abstract 4575: Chimeric antigen receptor macrophages (CARMA) for adoptive cellular immunotherapy of solid tumors

Chimeric antigen receptor (CAR) T cell immunotherapy has demonstrated profound results in hematologic malignancies but clinical efficacy in the solid tumor setting has not been observed. Barriers to T cell entry and function may partially explain this observation. As solid tumors actively recruit myeloid cells, we hypothesized that macrophages have the potential to be a powerful cellular immunotherapeutic agent in this setting if properly activated and redirected. We here describe the development of CAR macrophages (CARMA), demonstrating the feasibility, mechanism, and efficacy of this platform. To examine the function of CARs in macrophages, first generation anti-CD19, anti-mesothelin, or anti-HER2 CARs with a CD3ζ intracellular domain were introduced into the THP1 macrophage model. In vitro function was assessed via quantitative phagocytosis and luciferase-based specific killing assays. CARMA selectively phagocytosed and cleared cognate antigen-bearing tumor cells. To demonstrate the requirement for CAR-mediated intracellular signaling for activity, a CD3ζ-null CAR construct was tested in vitro. The deletion of CD3ζ significantly reduced the phagocytic and killing capacity (p 70% CAR expression). Ad5f35 transduction polarized human macrophages toward a durable immunostimulatory M1 phenotype and rendered CARMA resistant to subversion toward the immunosuppressive M2 phenotype, as defined by surface markers and metabolomics. CARMA enhanced the proliferative capacity of CD8+ T cells in phytohemagglutinin activation assays and secreted factors that activated by-stander macrophages. Primary human anti-HER2 CARMA demonstrated targeted phagocytosis and killing of HER2 expressing ovarian and breast cancer cell lines, and exhibited a six-fold higher luciferase-based killing capacity of SKOV3 cells compared to trastuzumab in vitro (p=0.002). Anti-HER2 CARMA was evaluated in vivo in an intraperitoneal (IP) SKOV3 ovarian cancer xenograft model. Mice that received IP CARMA had a decrease in tumor burden of approximately two orders of magnitude and had a 30-day survival benefit relative to untreated or control macrophage treated mice (p=0.018). In a systemically disseminated SKOV3 model, a single dose of IV CARMA led to a durable anti-tumor response (38-fold reduction relative to control on day 31 post-treatment; p=0.016) Lastly, we demonstrated that the blockade of the anti-phagocytic CD47/SIRPα axis enhanced the phagocytic capacity of CARMA. In summary, we here demonstrate that human macrophages engineered with a CAR exhibit targeted anti-tumor function in both in vitro and in vivo preclinical models. This novel cellular immunotherapeutic approach has a clear translational potential for the treatment of solid tumors. Citation Format: Michael Klichinsky, Marco Ruella, Olga Shestova, Saad S. Kenderian, Miriam Y. Kim, Roddy O9Connor, John Scholler, Carl June, Saar Gill. Chimeric antigen receptor macrophages (CARMA) for adoptive cellular immunotherapy of solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4575. doi:10.1158/1538-7445.AM2017-4575

EPHB4 is a therapeutic target in AML and promotes leukemia cell survival via AKT

EPHB4, an ephrin type B receptor, is implicated in the growth of several epithelial tumors and is a promising target in cancer therapy; however, little is known about its role in hematologic malignancies. In this article, we show that EPHB4 is highly expressed in ∼30% of acute myeloid leukemia (AML) samples. In an unbiased RNA interference screen of primary leukemia samples, we found that EPHB4 drives survival in a subset of AML cases. Knockdown of EPHB4 inhibits phosphatidylinositol 3-kinase/AKT signaling, and this is accompanied by a reduction in cell viability, which can be rescued by a constitutively active form of AKT. Finally, targeting EPHB4 with a highly specific monoclonal antibody (MAb131) is effective against AML in vitro and in vivo. EPHB4 is therefore a potential target in AML with high EPHB4 expression.

Abstract 1758: Targeting EphB4 with a novel antibody in acute leukemia

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Introduction: EphB4, a receptor tyrosine kinase, binds to ephrinB2, a cell surface ligand, resulting in bidirectional signaling through both receptor and ligand. EphB4 stimulates cell proliferation and migration through the phosphatidylinositol 3-kinase (PI3K) and Akt signaling pathway. MAb131 is a novel anti-EphB4 monoclonal antibody that induces degradation of EphB4 through receptor endocytosis. We investigated the use of MAb131 as a therapeutic agent for acute leukemia. Methods: Peripheral blood or bone marrow specimens from patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) were obtained after informed consent. EphB4 and ephrinB2 expression in cells were profiled using flow cytometry. Cell lines and patient samples were treated with MAb131 at 0, 10 and 100ug/ml concentrations. Blocking experiment was performed with 200ug/ml sEphB4-HSA in combination with 10ug/ml MAb131. Downregulation of EphB4 was evaluated by flow cytometry. Phosphorylated AKT (pAKT) levels were measured by Western blot. Cell viability was measured by trypan blue exclusion. Results: EphB4 was highly expressed on the cell surface in the majority of leukemia cell lines of both myeloid (K562, Molm14, U937) and lymphoid (REH, RS4;11, Jurkat) origin; only one leukemia cell line evaluated, KG-1, did not express EphB4. In contrast, none of the lymphoma cell lines (BJAB, Ramos, Namwala) expressed EphB4. Of 9 AML patient samples evaluated, 4 expressed high levels of EphB4, and 5 expressed low levels of EphB4. Of 7 ALL patient samples evaluated, 2 expressed high levels of EphB4, 3 had low expression and 2 did not express EphB4. None of the cells showed robust expression of ephrinB2. Treatment of ALL and AML cell lines with MAb131 induced downregulation of EphB4, decreased levels of pAKT, and >90% cell death after 72h. Primary AML and ALL samples also showed downregulation of surface EphB4 and increased cell death with MAb131 treatment. A decoy receptor comprised of the soluble extracellular domain of EphB4 fused to albumin (sEphB4-HSA) was used to block MAb131 binding to EphB4 and confirm specificity of MAb131 activity. Conclusion: We present the first report that EphB4 signaling is active in acute leukemia and can be targeted therapeutically. MAb131, a novel anti-EphB4 antibody, has potent anti-leukemic activity as a single agent in vitro and is likely to sensitize leukemia to cytotoxic chemotherapy through downregulation of AKT signaling. Based on these results, clinical studies exploring the efficacy of EphB4/ephrinB2 antagonists in patients with acute leukemia should be pursued. Citation Format: Miriam Y. Kim, Aparna Jorapur, Amy R. McManus, Ren Liu, Valery Krasnoperov, Kranthi Naga, Parkash S. Gill, Akil Merchant. Targeting EphB4 with a novel antibody in acute leukemia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1758. doi:10.1158/1538-7445.AM2014-1758

Anemia of Chronic Kidney Disease in Diabetic Patients: Pathophysiologic Insights and Implications of Recent Clinical Trials

The goals for this chapter are to succinctly describe the definition of anemia, and to describe the pathophysiology and the epidemiology of anemia in diabetic patients with chronic kidney disease. In addition, the cardiovascular risk factors of anemic patients will be explained and a table will be included. A comprehensive visualization will be included which will incorporate the pathophysiology of anemia in chronic kidney disease and the negative impact of anemia on the cardiovascular system. Reasons to treat anemia in this population will be presented. Furthermore, the recent clinical trials on anemia treatment in the diabetic patient with chronic kidney disease will be discussed, including but not limited to the CHOIR, CREATE, ACORD and TREAT trials. Lastly, there will be a summary of the most important points of the chapter. CHOIR (Correction of Hemoglobin and Outcomes in Renal Insufficiency), CREATE (Cardiovascular Risk Reduction by Early Anemia Treatment with Epoetin Beta), ACORD (Anemia Correction in Diabetes) and TREAT (Trial to Reduce Cardiovascular Events with Aranesp Therapy) trials. With the ongoing pandemic of obesity, diabetes and hypertension, chronic kidney disease is becoming a leading global health problem. Diabetes is currently the most common cause of chronic kidney disease [1]. Patients with diabetes and chronic kidney disease have an increased risk for anemia. Anemia is a risk factor for cardiac dysfunction and is potentially modifiable. Therefore it should be screened for readily in the diabetic population, a particularly vulnerable population, and it should be identified and rectified promptly. However all too often this is not the case.