Clinical responses and pharmacokinetics of fully human BCMA targeting CAR T-cell therapy in relapsed/refractory multiple myeloma.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 8013-8013 ◽  
Author(s):  
chunrui li ◽  
Jianfeng Zhou ◽  
Jue Wang ◽  
Guang Hu ◽  
Aihua Du ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Rapid Response ◽  
High Dose ◽  
T Cell Therapy ◽  
Refractory Multiple Myeloma ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

8013 Background: Previous studies indicate patients with relapsed/refractory multiple myeloma (RRMM) who receive high-dose BCMA-targeting CAR-T cells may achieve better remission but have worse adverse events. Moreover, once the disease progresses again, the re-infusion of CAR-T cells is not effective. To solve this dilemma, we have developed a novel BCMA-targeting CAR-T (CT103A) with a lentiviral vector containing a CAR structure with a fully human scFv, CD8a hinger and transmembrane, 4-1BB co-stimulatory and CD3z activation domains. Methods: ChiCTR1800018137 is a single-center and single-arm trial of CT103A in patients with RRMM. The primary objectives are to characterize the safety and tolerability in patients with R/R MM. The secondary objectives include evaluation of anti-myeloma activity, cytokines, CAR-T cell persistence, and pharmacokinetics. Between September 21, 2018, and January 21, 2019, nine patients (including 3 patients having relapsed after being given a murine BCMA CAR-T) received CT103A in 3+3 dose-escalation trial (three doses at 1, 3, 6 ×106/kg) after a conditioning chemotherapy regimen of cyclophosphamide and fludarabine. All Patients had received a median of 4 prior lines (range 3 - 5) of MM therapy. Results: At the time of the February 4, 2019 data analysis, the overall response rate was 100% (Table), and all patients had a rapid response within 14 days, with 67% (2/3) reaching CR/sCR at the lowest dose. The pharmacokinetics of CT103A were assessed by a digital polymerase chain reaction. Robust expansions were seen even at the lowest dosage level. In addition, Cmax and AUC0-28 reached levels comparable to reported CD19 CAR-T. In the first two dose groups, the grade of cytokine release syndrome (CRS) was 0 - 2. In the 6 ×106 /kg dose group, DLT had been observed in one patient. Conclusions: Data from this early-stage clinical study showed the unparalleled safety and efficacy of CT103A. Major AEs were transient, manageable, and reversible. three patients who relapsed the murine BCMA CAR-T were treated with CT103A, two patients achieved CR, and one patient achieved VGPR. 100% ORR and a rapid response within 2 weeks, suggests CT103A could be developed as a competitive therapeutic to treat patients with RRMM. Treatment Response (Case 1,5 and 7 are patients who relapsed the murine BCMA CAR-T). Clinical trial information: ChiCTR1800018137. [Table: see text]

scholarly journals Paving the Way toward Successful Multiple Myeloma Treatment: Chimeric Antigen Receptor T-Cell Therapy

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 983 ◽  
Author(s):  
Ewelina Grywalska ◽  
Barbara Sosnowska-Pasiarska ◽  
Jolanta Smok-Kalwat ◽  
Marcin Pasiarski ◽  
Paulina Niedźwiedzka-Rystwej ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Side Effects ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

Despite the significant progress of modern anticancer therapies, multiple myeloma (MM) is still incurable for the majority of patients. Following almost three decades of development, chimeric antigen receptor (CAR) T-cell therapy now has the opportunity to revolutionize the treatment landscape and meet the unmet clinical need. However, there are still several major hurdles to overcome. Here we discuss the recent advances of CAR T-cell therapy for MM with an emphasis on future directions and possible risks. Currently, CAR T-cell therapy for MM is at the first stage of clinical studies, and most studies have focused on CAR T cells targeting B cell maturation antigen (BCMA), but other antigens such as cluster of differentiation 138 (CD138, syndecan-1) are also being evaluated. Although this therapy is associated with side effects, such as cytokine release syndrome and neurotoxicity, and relapses have been observed, the benefit–risk balance and huge potential drive the ongoing clinical progress. To fulfill the promise of recent clinical trial success and maximize the potential of CAR T, future efforts should focus on the reduction of side effects, novel targeted antigens, combinatorial uses of different types of CAR T, and development of CAR T cells targeting more than one antigen.

A Phase I Study of a Novel Fully Human BCMA-Targeting CAR (CT103A) in Patients with Relapsed/Refractory Multiple Myeloma

Blood ◽  
2021 ◽  
Author(s):  
Di Wang ◽  
Jue Wang ◽  
Guang Hu ◽  
Wen Wang ◽  
Yi Xiao ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Phase I ◽  
Complete Response ◽  
Clinical Trial Registry ◽  
T Cell Therapy ◽  
Refractory Multiple Myeloma ◽  
Car T Cell ◽  
Car T

B cell maturation antigen- (BCMA) specific chimeric antigen receptor (CAR) T-cell therapies have shown efficacy in relapsed, refractory multiple myeloma (RRMM). Since the non-human originated antigen-targeting domain may limit clinical efficacy, we developed a fully human BCMA-specific CAR, CT103A, and report its safety and efficacy in a phase I trial. Eighteen consecutive RRMM patients, including four patients with prior murine BCMA CAR exposures, were enrolled. CT103A was administered at 1, 3, and 6 × 106 CAR-positive T cells/kg in the dose-escalation phase, and 1 × 106 CAR-positive T cells/kg in the expansion cohort. The overall response rate (ORR) was 100%, with 72.2% of the patients achieving complete response or stringent complete response (sCR). For the four murine BCMA CAR-exposed patients, three achieved sCR, and one achieved a very good partial response. At one year, the progression-free survival rate was 58.3% for all cohorts and 79.1% for the patients without extramedullary myeloma. Hematologic toxicities were the most common adverse events. 70.6% of the patients experienced grade 1 or 2 cytokine release syndromes. No immune effector cell-associated neurotoxicity syndrome was observed. To the cutoff date, CAR transgenes were detectable in 77.8% of the patients. The median CAR transgene persistence was 307.5 days. Only one patient was positive for the anti-drug antibody. Altogether, CT103A is safe and highly active in RRMM patients and can be developed as a promising therapy for RRMM. Patients who relapsed from prior murine BCMA CAR T-cell therapy may still benefit from CT103A. (Chinese Clinical Trial Registry ChiCTR1800018137)

scholarly journals Any closer to successful therapy of multiple myeloma? CAR-T cell is a good reason for optimism

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Faroogh Marofi ◽  
Safa Tahmasebi ◽  
Heshu Sulaiman Rahman ◽  
Denis Kaigorodov ◽  
Alexander Markov ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
Survival Rate ◽  
T Cell ◽  
Plasma Cells ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

AbstractDespite many recent advances on cancer novel therapies, researchers have yet a long way to cure cancer. They have to deal with tough challenges before they can reach success. Nonetheless, it seems that recently developed immunotherapy-based therapy approaches such as adoptive cell transfer (ACT) have emerged as a promising therapeutic strategy against various kinds of tumors even the cancers in the blood (liquid cancers). The hematological (liquid) cancers are hard to be targeted by usual cancer therapies, for they do not form localized solid tumors. Until recently, two types of ACTs have been developed and introduced; tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR)-T cells which the latter is the subject of our discussion. It is interesting about engineered CAR-T cells that they are genetically endowed with unique cancer-specific characteristics, so they can use the potency of the host immune system to fight against either solid or liquid cancers. Multiple myeloma (MM) or simply referred to as myeloma is a type of hematological malignancy that affects the plasma cells. The cancerous plasma cells produce immunoglobulins (antibodies) uncontrollably which consequently damage the tissues and organs and break the immune system function. Although the last few years have seen significant progressions in the treatment of MM, still a complete remission remains unconvincing. MM is a medically challenging and stubborn disease with a disappointingly low rate of survival rate. When comparing the three most occurring blood cancers (i.e., lymphoma, leukemia, and myeloma), myeloma has the lowest 5-year survival rate (around 40%). A low survival rate indicates a high mortality rate with difficulty in treatment. Therefore, novel CAR-T cell-based therapies or combination therapies along with CAT-T cells may bring new hope for multiple myeloma patients. CAR-T cell therapy has a high potential to improve the remission success rate in patients with MM. To date, many preclinical and clinical trial studies have been conducted to investigate the ability and capacity of CAR T cells in targeting the antigens on myeloma cells. Despite the problems and obstacles, CAR-T cell experiments in MM patients revealed a robust therapeutic potential. However, several factors might be considered during CAR-T cell therapy for better response and reduced side effects. Also, incorporating the CAT-T cell method into a combinational treatment schedule may be a promising approach. In this paper, with a greater emphasis on CAR-T cell application in the treatment of MM, we will discuss and introduce CAR-T cell’s history and functions, their limitations, and the solutions to defeat the limitations and different types of modifications on CAR-T cells.

scholarly journals Preclinical Evaluation of CD8+ Anti-Bcma mRNA CAR T-Cells for the Control of Human Multiple Myeloma

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1811-1811 ◽  
Author(s):  
Liang Lin ◽  
Lijie Xing ◽  
Shih-Feng Cho ◽  
Kenneth Wen ◽  
Phillip A Hsieh ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Advisory Board ◽  
Dependent Manner ◽  
T Cell Therapy ◽  
Safety Risk ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Chimeric antigen receptor (CAR) T cells targeting BCMA are positioned to transform treatment of multiple myeloma (MM), and virally-generated anti-BCMA CAR T cells have shown impressive early stage clinical results. However, the safety risk/benefit, manufacturing constraints, and relevant patient populations of viral anti-BCMA CAR T have yet to be fully defined. Here we present preclinical characterization of an autologous mRNA-generated anti-BCMA CAR T cell product (Descartes-08) designed to reduce safety risk and broaden the fitness-for-use of anti-BCMA CAR T cell therapy. Descartes-08 are autologous CD8+ T cells that express anti-BCMA CAR on up to 90% of cells with duration of CAR expression for several days with subsequent reduction in expression to background approximately 1 week after their generation. The manufacturing process is clinically scalable with high purity and viability of Descartes-08 following cryopreservation. Descartes-08 undergo cytotoxic degranulation and produce cytokines IFNg, TNFα, IL-2, in response to multiple BCMA-expressing multiple myeloma target cell lines in an effector-to-target-ratio-dependent manner. Furthermore, Descartes-08 kills MM lines that are both resistant and sensitive to lenalidomide and pomalidomide, and/or MM cells that are grown in the presence of bone marrow stromal cells that clinically support MM survival. Moreover, Descartes-08 are highly cytotoxic against MM cells from both newly-diagnosed and relapsed patients. The magnitude of cytolytic and cytokine responses correlates with duration of anti-BCMA CAR expression and declines after 4 days, indicating a temporal limit in activity that is predicted to dramatically decrease the risk of severe cytokine release syndrome. In a mouse model of disseminated human MM, Descartes-08 shows CAR-specific suppression of myeloma that is maintained throughout the duration of treatment. Taken together, these results illustrate features of RNA-generated anti-BCMA CAR T cells that promise key clinical advantages, thereby supporting ongoing clinical development of Descartes-08 for treatment of MM (NCT03448978). Disclosures Kurtoglu: Cartesian Therapeutics: Employment. Zhang:Cartesian Therapeutics: Employment. Stewart:Cartesian Therapeutics: Employment. Anderson:Sanofi-Aventis: Other: Advisory Board; OncoPep: Other: Scientific founder ; C4 Therapeutics: Other: Scientific founder ; Gilead Sciences: Other: Advisory Board; Janssen: Other: Advisory Board.

scholarly journals Systematically optimized BCMA/CS1 bispecific CAR-T cells robustly control heterogeneous multiple myeloma

2020 ◽  
Author(s):  
Eugenia Zah ◽  
Eunwoo Nam ◽  
Vinya Bhuvan ◽  
Uyen Tran ◽  
Brenda Y. Ji ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
B Cell ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

ABSTRACTChimeric antigen receptor (CAR)-T cell therapy has shown remarkable clinical efficacy against B-cell malignancies but also demonstrated marked vulnerability to antigen escape and tumor relapse. Here, we report the rational design and systematic optimization of bispecific CAR-T cells with robust activity against multiple myeloma (MM), including heterogeneous MM that is resistant to conventional CAR-T cell therapy targeting B-cell maturation antigen (BCMA). We demonstrate that BCMA/CS1 bispecific CAR-T cells exhibit significantly higher CAR expression levels and greater antigen-stimulated proliferation compared to T cells that co-express individual BCMA and CS1 CARs. Compared to single-input BCMA- or CS1-targeting CAR-T cells, BCMA/CS1 bispecific CAR-T cells significantly prolong the survival of animals bearing heterogeneous MM tumors. Combination therapy with anti–PD-1 antibody further accelerates the rate of initial tumor clearance in vivo, but CAR-T cell treatment alone was able to achieve durable tumor-free survival even upon tumor re-challenge. Taken together, the BCMA/CS1 bispecific CAR presents a promising treatment approach to prevent antigen escape in CAR-T cell therapy against MM, and the vertically integrated optimization process can be used to develop robust cell-based therapy against novel disease targets.

scholarly journals Future of CAR T cells in multiple myeloma

Hematology ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 272-279 ◽  
Author(s):  
Kitsada Wudhikarn ◽  
Sham Mailankody ◽  
Eric L. Smith
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Early Clinical Trial ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

Abstract Despite the significant improvement in survival outcomes of multiple myeloma (MM) over the past decade, it remains an incurable disease. Patients with triple-class refractory MM have limited treatment options and a dismal prognosis. Chimeric antigen receptor (CAR) T-cell therapy targeting B-cell maturation antigen has transformed the treatment armamentarium of relapsed/refractory MM (RRMM), with unprecedented overall response rates in this difficult-to-treat patient population. However, a significant proportion of patients ultimately relapse despite achieving deep remission. Several innovative approaches, including alternative/dual-antigen–specific CAR T-cell constructs, genetically engineered “off-the-shelf” CAR T cells, and strategies to counteract an immunosuppressive microenvironment, may dramatically reshape the field of CAR T-cell therapy in the future. These strategies are being actively investigated in preclinical and early clinical trial settings with the hopes of enhancing the durability of responses and, thereby, improving the overall survival of RRMM patients after CAR T-cell therapy.

Bispecific CART cells in the treatment of relapsed and refractory multiple myeloma: A review of literature.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e20038-e20038
Author(s):  
Joshua Christy ◽  
Abdul Rafae ◽  
Nazma Hanif ◽  
Pranali Santhoshini Pachika ◽  
Emad Kandah ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Clinical Trials ◽  
T Cells ◽  
T Cell ◽  
Dose Range ◽  
Refractory Multiple Myeloma ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

e20038 Background: Chimeric antigen receptor T cells (CART) have shown promising results in the treatment of relapsed and refractory multiple myeloma (RRMM). Recently, bispecific-CART cells targeting 2 antigens are being evaluated in various clinical trials. Methods: A comprehensive literature search was done of Pubmed, Embase, and Cochrane. Data presented at annual hematology and oncology conferences were also included. Results: We included 4 phase I clinical trials with a total of 77 RRMM patients between the ages of 18 to 71 years. The median follow-up duration ranged from 1 month to 27.5 months. All were lymphodepleted with Cyclophosphamide and Fludarabine before receiving CAR-T cell therapy. The CAR-T cell targets include BCMA and CD38 (dose range 0.5 x 10^6 - 4 x 10^6 cells/kg), BCMA and TACI (dose range 15 - 900 x 10e6 CAR-T cells), BCMA and CD19 (1 x 10e5/kg - 3 x 10e5 CAR-T cells/kg), and BCMA and CD19 (dose 1 x 10e6 cells/kg). Overall response rate (ORR) was reported by 4 trials (87.5%, 43%, 93.8%, 95%). Complete response (CR) was also reported in 4 trials as 50%, 64%, 56.3% and 14% and partial response (PR) reported as 25%, 28%, 16.6%, 14%, 18% in 5 trials (table). The most common grade 3-4 adverse effects that were reported include cytokine release syndrome, neurotoxicity, neutropenia, lymphopenia, anemia, thrombocytopenia, diarrhea, increased LDH, lower respiratory tract infections (LRTI), dehydration, renal failure (table). Yan et al. reported one death due to cerebral hemorrhage which was considered unrelated to treatment. Jiang et al. reported one death from unknown cause of a patient who presented with fever during the COVID- 19 pandemic. Conclusions: Bispecific CART cells have shown promising results in the treatment of RRMM. However, the clinical trials are ongoing, and a longer follow-up is needed.[Table: see text]

scholarly journals Perspectives for the Use of CAR-T Cells for the Treatment of Multiple Myeloma

2021 ◽  
Vol 12 ◽  
Author(s):  
Marcin Jasiński ◽  
Grzegorz W. Basak ◽  
Wiesław W. Jedrzejczak
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Advantages And Disadvantages ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

During recent years considerable progress has been made in the treatment of multiple myeloma. However, despite the current improvements in the prognosis of this malignancy, it always ends with relapse, and therefore new therapy approaches for destroying resistant cancer cells are needed. Presently, there is great hope being placed in the use of immunotherapy against refractory/relapsed multiple myeloma which is unresponsive to any other currently known drugs. The most promising one is CAR-T cell therapy which has already shown tremendous success in treating other malignancies such as acute lymphoblastic leukaemia (ALL) and could potentially be administered to multiple myeloma patients. CAR-T cells equipped with receptors against BCMA (B-cell maturation antigen), which is a surface antigen that is highly expressed on malignant cells, are now of great interest in this field with significant results in clinical trials. Furthermore, CAR-T cells with other receptors and combinations of different strategies are being intensively studied. However, even with CAR-T cell therapy, the majority of patients eventually relapse, which is the greatest limitation of this therapy. Serious adverse events such as cytokine release syndrome or neurotoxicity should also be considered as possible side effects of CAR-T cell therapy. Here, we discuss the results of CAR-T cell therapy in the treatment of multiple myeloma, where we describe its main advantages and disadvantages. Additionally, we also describe the current results that have been obtained on using combinations of CAR-T cell therapies with other drugs for the treatment of multiple myeloma.

scholarly journals A Bispecific CAR-T Cell Therapy Targeting Bcma and CD38 for Relapsed/Refractory Multiple Myeloma: Updated Results from a Phase 1 Dose-Climbing Trial

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 930-930 ◽  
Author(s):  
Chenggong Li ◽  
Heng Mei ◽  
Yu Hu ◽  
Tao Guo ◽  
Lin Liu ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Phase 1 ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

Background: Anti-B cell maturation antigen (BCMA) chimeric antigen receptor(CAR) T cell therapy has shown promising results from a series of clinical trials. But short progression-free survival (PFS) due to BCMA-negative or positive relapse is pretty much the agenda.Here we constructed a dual-target BM38 CAR incorporating the anti-CD38 and anti-BCMA single-chain variable fragment in tandem plus 4-1BB signaling and CD3 zeta domains and conducted the first-in-human clinical trial(ChiCTR1800018143) in patients with RRMM to evaluate the safety, efficacy and duration of BM38 T cells. Methods:Patients with relapsed or refractory multiple myeloma(RRMM), who had received at least 2 prior treatment regimens, including a proteasome inhibitor and an immunomodulatory agent, were enrolled in the phase 1 dose-climbing trial of the bispecific CAR-T cell therapy. Patients were subjected to a lymphodepleting regimen with Cy(250 mg/m2, d-5 to d-3) and Flu(25 mg/m2, d-5 to d-3) daily prior to the CAR-T infusion (d0). The dose gradients of infused CAR-T cells were 0.5, 1.0, 2.0, 3.0 and 4.0×106 cells/kg and at least 2 patients were involved at every dose level. The efficacy was assessed by the International Uniform Response Criteria for Multiple Myeloma (2016), and the toxicity was graded by CTCAE 5.0. Results: As of 31 July 2019, 16 pts consisting of 10(62.5%) with genetic abnormalities and 5(31.25%) with extramedullary lesions,had received BM38 CAR-T cells in the 5 dose-climbing cohorts. At a median follow-up of 36 weeks, no DLTs and no grade ≥ 3 neurotoxicities were observed. Cytokine release syndrome (CRS), mainly grade 1-2, was reported in 10 of 16 (62.5%) pts; 4 pts had grade ≥ 3 CRS that resolved by tocilizumab and supportive treatment. Almost all the pts were observed with hematological toxicities relieved in the first month after infusion.14(87.5%) pts achieved an overall response with 8(50%) sCR, 2(12.5%) VGPR and 4(25.00%) PR and 14(87.5%) reached bone marrow minimal residual disease(MRD)-negative status. The longest duration of sCR was over 51 weeks and 5(62.5%) of 8 patients had still maintained sCR and 2 transformed to VGPR and 1 to PR. The median duration of progression-free survival(PFS) had not been reached; PFS rates at 9 months was 75%. More encouragingly, 5(100%)extramedullary lesions were eliminated.Up to the observed day, the BM38 CAR-T cells still exist in the patients' peripheral blood by flow cytometry(FCM) and quantitative polymerase chain reaction(q-PCR). The peak time of CAR-T cells proliferation of sCR patients was about the 2nd week after infusion, which was earlier than other patients. 4.0 × 106 CAR T cells (pt11, 12 and 15) were selected for the optimal dose with superior response and acceptable toxicities and expansion cohort would be conducted. Conclusions:Our study demonstrates an improved efficacy with the bivalent BM38 CAR-T therapy for RRMM with a high ORR, especially a higher rate and a longer duration of sCR and effective elimination for extramedullary lesions. No neurotoxicity was observed. CRS and other toxicities were manageable. These initial data provide strong evidence to support the further development of the dual-target CAR-T therapy for RRMM. Clinical trial information: ChiCTR1800018143 Disclosures No relevant conflicts of interest to declare.

scholarly journals Developing a Safer Anti-CD44v6 Chimeric Antigen Receptor T Cell Against Hematological Cancers By Mitigating on-Target Off-Tumor Toxicity

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2796-2796
Author(s):  
Dennis Awuah ◽  
Lawrence Stern ◽  
Ian Schrack ◽  
Tae Yoon Kim ◽  
Joseph Cohen ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Soluble Scfv

Abstract Adoptively transferred chimeric antigen receptor (CAR) T cells have shown significant promise in targeted immunotherapy against hematological tumors, despite concerns with safety and antigen escape. The CD44 adhesion molecule, which binds components of ECM such as collagen and hyaluronan, has been implicated in growth and survival as well as metastasis of tumor initiating stem cells (TSCs). A splice variant of CD44, CD44v6 is broadly expressed on malignant tumors including AML, CML and multiple myeloma (MM), where it aids tumor migration and predicts poor disease prognosis 1. Moreover, the expression of CD44v6 on healthy tissues including keratinocytes, presents a significant challenge in 'on-target, off-tumor' toxicity 2,3. We have developed a second generation, anti-CD44v6 CAR T cell (CD44v6CAR) that mediates potent cytotoxic and effector function against AML and MM in-vitro. Additionally, we observed lesser potency of our CD44v6CAR T cells against MM in comparison with AML in-vivo. Interestingly, higher levels of soluble CD44v6 antigen were also detected in mice engrafted with MM.1S compared to THP1. Possibly, the presence of soluble CD44v6 in mouse serum culminated in reduced anti-tumor activity against MM in-vivo, most likely due to CAR scFv blockade with antigen. Here, we provide an alternative strategy for improving the CD44v6 CAR T cell therapy and mitigating on-target off-tumor toxicity using CD44v6 CAR T cells that secrete a soluble protease-susceptible version of the CAR-expressed CD44v6 scFv that will block CAR binding in healthy tissue, but will be cleaved by cancer-specific proteases in the tumor site, allowing for CAR T cell binding and activation (Figure 1). We leveraged the presence of matrix metalloproteinase (MMP)-2, which is significantly overexpressed in multiple myeloma tumor microenvironment 4 to develop a modified CAR T construct (sCD44v6CAR) with engineered MMP-2 cut site in the linker between the heavy and light chains of the soluble CD44v6scFv. Kinetic analysis with varying MMP-2 concentration and digestion time showed moderate proteolytic susceptibility of our scFv construct, with digestion efficiency increasing in a dose-dependent manner. Furthermore, our engineered protease-liable scFv demonstrated higher affinity for CD44v6 antigen binding in titration assays compared to CAR scFv suggesting that engineered scFv are able to 1) bind and neutralize soluble antigen and 2) bind antigen on healthy tissues with high affinity to mitigate off-tumor toxicity. As expected, both conventional (CD44v6CAR) and modified sCD44v6 CAR T cells showed effective cytotoxicity against AML in vitro. Interestingly, cytotoxic activity against MM.1S using the modified T cells (sCD44v6CAR) was significantly suppressed, likely resulting from secretion of soluble scFv. The addition of recombinant MMP-2 in co-culture assays cleaved soluble scFvs, rescuing CAR-mediated tumor killing. Taken together, the data confirms our proof-of-concept hypothesis and highlights the protective capacity of engineered sCD44v6CAR T cells, with its ability to potentially neutralize off-target toxicity and improve anti-MM activity in future studies, which has impact on the CAR T cell therapy as a general strategy. Figure 1: Schematic representation of CAR T Cell mitigating off-disease recognition. Presence of protease-susceptible linker in soluble scFv is efficiently cleaved by tumor-specific proteases in tumor microenvironment enabling CAR binding and activation. Lack of specific proteases in healthy tissues leads to high affinity, soluble scFv-target binding and effective blocking. References 1. Heider, K. H., Kuthan, H., Stehle, G. & Munzert, G. CD44v6: a target for antibody-based cancer therapy. Cancer Immunol Immunother 53, 567-579, (2004). 2. Casucci, M. et al. CD44v6-targeted T cells mediate potent antitumor effects against acute myeloid leukemia and multiple myeloma. Blood 122, 3461-3472, (2013). 3. Riechelmann, H. et al. Phase I trial with the CD44v6-targeting immunoconjugate bivatuzumab mertansine in head and neck squamous cell carcinoma. Oral Oncology 44, 823-829, (2008). 4. Shay, G. et al. Selective inhibition of matrix metalloproteinase-2 in the multiple myeloma-bone microenvironment. Oncotarget 8, 41827-41840, (2017). Figure 1 Figure 1. Disclosures Forman: Allogene: Consultancy; Mustang Bio: Consultancy, Current holder of individual stocks in a privately-held company; Lixte Biotechnology: Consultancy, Current holder of individual stocks in a privately-held company. Wang: Pepromene Bio, Inc.: Consultancy.

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