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899 Evaluation of In Vivo CAR Transgene Levels in Relapsed/Refractory Pediatric and Young Adult ALL and Adult DLBCL Tisagenlecleucel-Treated Patients

Program: Oral and Poster Abstracts
Type: Oral
Session: 612. Acute Lymphoblastic Leukemia: Clinical Studies: Improving Outcomes with Cellular Therapy
Hematology Disease Topics & Pathways:
Biological, Therapies, CAR-Ts
Monday, December 3, 2018: 5:30 PM
Room 6A (San Diego Convention Center)

Rakesh Awasthi1*, Karen Thudium Mueller, PharmD, MSc1*, Gregory A. Yanik, MD2*, Constantine S. Tam, MBBS (Hons), MD, FRACP, FRCPA3, Susana Rives4*, Joseph P. McGuirk, DO5, Michael A. Pulsipher, MD6, Michael W. Boyer, MD7, Ulrich Jaeger, MD8, Andre Baruchel, MD9, Gary Douglas Myers, MD10*, Hyatt Balke-Want, MD11*, Stephen J. Schuster, MD12, Heather Stefanski, MD, PhD13, Michael R. Bishop, MD14, Edward R. Waldron, PhD, MSc, BSc15*, Özlem Anak, MD16*, Abhijit Chakraborty, PhD15*, Eric Bleickardt, MD15*, Stephane Wong, PhD, MBA17*, Lida Bubuteishvili Pacaud, MD15*, Edmund K. Waller, MD18 and Shannon L. Maude, MD, PhD19,20

1Novartis Institutes for BioMedical Research, East Hanover, NJ
2C.S. Mott Children’s Hospital, Ann Arbor, MI
3St Vincent’s Hospital and University of Melbourne, Peter MacCallum Cancer Centre, Melbourne, Australia
4Department of Pediatric Hematology and Oncology, Hospital Sant Joan de Déu de Barcelona, Barcelona, ESP
5Department of Blood and Bone Marrow Transplant, The University of Kansas Medical Center, Kansas City, KS
6Division of Hematology, Oncology, and Blood and Marrow Transplantation, Children’s Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, CA
7Department of Pediatrics and Internal Medicine, University of Utah, Salt Lake City, UT
8Dept. of Medicine I, Division of Hematology and Hemostasis, Medical University of Vienna, Vienna, Austria
9Department of Pediatric Hematology and Immunology, AP-HP, Robert Debré Hospital, Paris, Paris, France
10Children’s Mercy Hospital, Kansas City, MO
11Department for Hematology & Oncology, University Hospital of Cologne, Cologne, Germany
12Lymphoma Program, Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA
13Department of Pediatric Blood and Marrow Transplant, University of Minnesota, Minneapolis, MN
14Hematopoietic Cellular Therapy Program, The University of Chicago Medicine, Chicago, IL
15Novartis Pharmaceuticals Corporation, East Hanover, NJ
16Novartis Pharma AG, Basel, Switzerland
17Novartis Pharmaceuticals Corporation, Cambridge, MA
18Bone Marrow and Stem Cell Transplant Center, Winship Cancer Institute of Emory University, Atlanta, GA
19Division of Oncology, Center for Childhood Cancer Research and Cancer Immunotherapy Program, Children's Hospital of Philadelphia, Philadelphia, PA
20Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA

Background

Quantitative polymerase chain reaction (qPCR) is an analytical method that has been used to investigate the in vivo kinetics of chimeric receptor antigen (CAR) transgene following the infusion of tisagenlecleucel. B cell aplasia, likely an “on-target toxicity” of tisagenlecleucel, has been considered a measure of functional persistence. (Maude SL et al. Blood 2015;125(26):4017-4023) Although the CAR transgene can be detected in peripheral blood of tisagenlecleucel treated patients, it is unclear whether CAR transgene detection by qPCR could be reliably used to inform treatment decision in an individual patient.

Methods

Transgene levels in blood measured by qPCR from pivotal phase II studies in relapsed/refractory (r/r) pediatric and young adult acute lymphoblastic leukemia (B-ALL) patients (pts) (ELIANA [NCT02435849, N=75]; ENSIGN [NCT02228096, N=29]) and adult diffuse large B cell lymphoma (DLBCL) pts (JULIET [NCT02445248, N=93]) were used to investigate the relationship between transgene persistence and clinical response.

Results

To determine whether CAR qPCR measurements are associated with or predictive of response, CAR transgene levels and timing of peak levels were examined. In both ALL and DLBCL pts, there were detectable CAR transgene levels by qPCR in both responders and non-responders. The geometric mean maximal expansion (geo mean Cmax) was similar between responding and non-responding adult DLBCL pts, while 1.7 fold differences were observed in pediatric ALL pts (geo mean Cmax in copies/µg: responders, 32700, n=79; non-responders, 19500, n=10; Table 1). For both DLBCL and ALL pts, high inter-individual variability in transgene levels was noted. Similarly, higher CAR-T cell expansion from flow cytometry data pooled from responding pediatric ALL and chronic lymphocytic leukemia (CLL) pts were observed relative to non-responding pts (Mueller KT et al. Blood 2017;130(21):2317-2325), while the levels in DLBCL pts were comparatively lower in blood, likely due to partitioning of functional CAR-T cells to the target sites including lymph nodes.

The median time to maximal transgene level ranged from 9-10 days in DLBCL responders and non-responders and pediatric ALL responders, while non-responding pediatric ALL pts showed delayed expansion with median Tmax of 20 days. The median time corresponding to last quantifiable transgene level (Tlast), an indicator of persistence, was higher in responding pts compared to non-responding pts, indicating a trend for longer persistence in both DLBCL and ALL pts with continued response (Table 1). Similarly, the half-life estimated from the terminal slope of the cellular kinetic profile, an additional indicator of persistence, was higher in responding pts relative to non-responding pts for both DLBCL and ALL (Table 1). Despite this general trend, in some cases, transgene levels were not detectable at later time points in pts with continued response.

The swimmer plot for representative responder ALL (Figure 1a) and DLBCL pts (Figure 1b) with responses and transgene levels demonstrate that although the majority of responding pts show persistent transgene levels, some pts maintained a favorable clinical response despite a decline in transgene levels to below the level of quantification of 50 copies/µg.

Conclusion

In both ALL and DLBCL, CAR transgene is initially detected at high levels with high variability in both responders and non-responders. While the majority of responding pts tend to have persistent transgene levels, some pts maintain favorable clinical responses despite a lack of quantifiable transgene. These results indicate that qPCR testing for CAR transgene in blood of tisagenlecleucel treated pts should not be used for making treatment decisions for individual pts. In addition, the qPCR measurements in peripheral blood do not reflect on the trafficking of CAR positive cells to sites outside peripheral blood.

The assessment by flow cytometry remains an important assay to distinguish high expression in responding vs non-responding pts in ALL and CLL, and further evaluation of target tissue is needed in DLBCL to understand the utility of CAR expression as a means to distinguish responder and non-responders. Also, further data are needed to improve our understanding of how CAR transgene levels relate to disease burden and duration of response and whether this information is clinically useful.

Disclosures: Awasthi: Exelixis: Equity Ownership; Celgene: Equity Ownership; Novartis Institutes for Biomedical Research: Employment. Mueller: Novartis Institutes for Biomedical Research: Employment; Novartis Pharmaceuticals Corporation: Equity Ownership, Other: Patent pending. Tam: Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; BeiGene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Rives: Amgen: Other: Travel and accommodation for medical congresses, Speakers Bureau; Jazz Pharma: Honoraria, Other: Travel and accommodation for medical congresses, Speakers Bureau; Shire: Honoraria, Other: Travel and accommodation for medical congresses, Speakers Bureau; Servier: Honoraria, Other: Travel and accommodation for medical congresses, Speakers Bureau; Novartis Pharmaceuticals Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel and accommodation for medical congresses, Speakers Bureau; Baxalta: Honoraria, Other: Travel and accommodation for medical congresses, Speakers Bureau; Erytech Pharma: Other: Travel and accommodation for medical congresses, Speakers Bureau. McGuirk: Bellicum Pharmaceuticals: Research Funding; Fresenius Biotech: Research Funding; Novartis Pharmaceuticals Corporation: Honoraria, Other: speaker, Research Funding; Astellas Pharma: Research Funding; Gamida Cell: Research Funding; Kite Pharma: Honoraria, Other: travel accommodations, expenses, speaker ; Pluristem Ltd: Research Funding. Pulsipher: Amgen: Honoraria; CSL Behring: Consultancy; Novartis: Consultancy, Honoraria, Speakers Bureau; Adaptive Biotech: Consultancy, Research Funding. Jaeger: MSD: Research Funding; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Infinity: Membership on an entity's Board of Directors or advisory committees; Takeda-Millenium: Membership on an entity's Board of Directors or advisory committees; Takeda-Millenium: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bioverativ: Membership on an entity's Board of Directors or advisory committees. Baruchel: Novartis: Membership on an entity's Board of Directors or advisory committees; Shire: Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Travel, accommodations or expenses; Amgen: Consultancy; Roche: Consultancy; Servier: Consultancy; Celgene: Consultancy. Myers: Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Research Funding, Speakers Bureau. Balke-Want: Novartis Pharmaceuticals Corporation: Honoraria. Schuster: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Novartis Pharmaceuticals Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Honoraria, Research Funding; Dava Oncology: Consultancy, Honoraria; Nordic Nanovector: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Research Funding. Stefanski: Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Speakers Bureau. Bishop: Novartis Pharmaceuticals Corporation: Speakers Bureau; Juneau Therapeutics: Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees; United Healthcare: Employment. Waldron: Novartis Pharmaceuticals Corporation: Employment, Equity Ownership. Anak: Novartis Pharma AG: Employment. Chakraborty: Novartis Institutes for Biomedical Research: Employment. Bleickardt: Novartis Pharmaceuticals Corporation: Employment. Wong: Novartis Pharmaceuticals Corporation: Employment, Equity Ownership. Bubuteishvili Pacaud: Novartis Pharmaceuticals Corporation: Employment, Equity Ownership. Waller: Pharmacyclics: Other: Travel Expenses, EHA, Research Funding; Cambium Medical Technologies: Consultancy, Equity Ownership; Novartis Pharmaceuticals Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celldex: Research Funding; Kalytera: Consultancy; Cambium Oncology: Equity Ownership; Humanigen: Consultancy. Maude: Novartis Pharmaceuticals Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees.

*signifies non-member of ASH