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3192 Enhancing the Immune Surveillance in Multiple Myeloma Via CDK4/6 Inhibition

Program: Oral and Poster Abstracts
Session: 652. Myeloma: Pathophysiology and Pre-Clinical Studies, excluding Therapy: Poster III
Hematology Disease Topics & Pathways:
multiple myeloma, Diseases, Plasma Cell Disorders, Lymphoid Malignancies
Monday, December 7, 2020, 7:00 AM-3:30 PM

Yan Xu, MD1,2*, Yao Yao3*, Woojun Daniel Park4, Sanika Derebail, MS5*, Chandraditya Chakraborty, PhD6*, Shidai Mu2*, Rafael Alonso Fernández2,7*, Srikanth Talluri, PhD8,9*, Zuzana Chyra, PhD10,11,12*, Kenneth Wen13*, Qingsheng Yan3*, Osasenaga Idahor3*, Selene Cipri3*, Rao Prabhala9,14, Kenneth Anderson, MD15, Mehmet K. Samur, PhD16*, Mariateresa Fulciniti, PhD17 and Nikhil C. Munshi, MD9,18

1Institute of Hematology & Blood Diseases Hospital, Department of Lymphoma & Myeloma, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China
2The LeBow Institute for Myeloma Therapeutics and Jerome Lipper Multiple Myeloma Center, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
3Dana Farber Cancer Institute, Boston, MA
4Baylor College of Medicine, Houston, TX
5Dana-Farber Cancer Institute, Boston, MA
6Jerome Lipper Multiple Myeloma Center, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
7Translational Hematology Group, Hospital 12 de Octubre-CNIO, Madrid, Spain
8The LeBow Institute for Myeloma Therapeutics and Jerome Lipper Multiple Myeloma Center, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, West Roxbury, MA
9VA Boston Healthcare System, Boston, MA
10University Hospital Ostrava, Department of Haemato-Oncology, Ostrava, Czech Republic
11Faculty of Medicine, University of Ostrava, Ostrava, Czech Republic
12Department of Medical Oncology, Dana Farber Cancer Institute, Harvard Medical School, Boston
13Jerome Lipper Multiple Myeloma Center, LeBow Institute for Myeloma Therapeutics, Dana-Farber Cancer Institute, Boston, MA
14DFCI/VABHS/Harvard Med. School, West Roxbury, MA
15Jerome Lipper Multiple Myeloma Center, LeBow Institute for Myeloma Therapeutics, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
16The Jerome Lipper Multiple Myeloma Center, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
17Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
18Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA

Deregulation of cyclin D genes is a uniform event in multiple myeloma (MM) and represent a striking addiction as observed in pan-cancer genome-wide CRISPR screening data. However, early stage Cyclin D and other cell cycle kinases inhibitors have shown a lack of single agent activity suggesting that targeting of cell cycle regulation is insufficient to produce a durable response in MM. Recent evidence recognizes the Cyclin D and CDK4 activities within the immune tumor microenvironment, supporting a previously unrecognized immunomodulatory functions of CDK4/6. This is particularly important in MM, a highly heterogeneous disease that resides in a complex ecosystem comprising of immune, endothelial, and stromal cells. We here evaluated the tumor intrinsic and extrinsic effects of CDK4/6 inhibition in MM with the goal to define rationally designed combination strategies to effectively impact MM growth.

We have evaluated MM cell sensitivity to CDK4/6 inhibitors (both Palbociclib and Abemaciclib) in a panel of 32 MM cell lines and primary MM patients’ samples. As expected, both inhibitors were mostly cytostatic with G0/G1 cell cycle arrest and significant impact on the pRB–E2F axis both in vitro as well as in vivo. In luminescence subcutaneous SCID models engrafted with H929 or MM1S MM cells expressing an E2F-driven luciferase reporter, treatment with low dose Palbociclib or Abemaciclib caused regression of bulky tumors, evidenced by a ~40% reduction in tumor volume at the 14-day end-point and a decreased E2F1 reporter activity.

We next studied genome-wide transcriptional response to treatment using RNA-seq analysis in two MM cell lines using multiple doses and duration (24 and 72 hours) to evaluate the effect of short and long exposure to the drug. Gene set enrichment analysis (GSEA) of RNA-seq data confirmed significant downregulation of proliferation and E2F target genes at 24 hours post treatment. Interestingly, after longer exposure to both drugs we observed modulation of signatures for Ag presentation (including upregulation of HLA-A,B, and C; B2MG), innate immune response (ICAM-1 and 2; IL-8 and several CCLs) and interferon inducible genes IFN response (IRF1, IRF9, STAT1, STAT2, STAT4, OSA1, OSA2, MX1).

To confirm genomic data and evaluate if CDK4/6i promotes the induction of the senescence-associated secretory phenotype (SASP) program in MM cells, we performed cytokine profile to assess the secretion of 174 soluble factors in the MM cell supernatant upon CDK4/6i. We confirmed a significant increase of chemokines involved in NK cell recruitment (CCL2, CCL4, CCL5), as well as cytokines that promote NK cell proliferation and activation. Moreover, we found that intercellular adhesion molecule–1 (ICAM-1) and the NKG2D ligands ULBP2 and MICA, required for activation of NK cell cytotoxicity and tumor cell targeting, were induced after CDK4/6i in MM cells. Although not secretory per se, these NK cell ligands are part of the transcriptional module linked to the SASP. Overall, these data suggest that, in addition to a more stable cell cycle arrest, CDK4/6i may promote MM cell immune surveillance through induction of the SASP program.

To further confirm the immune effects, we tested freshly isolated NK cells from MM patients and healthy donors using in vitro MM-NK cell coculture assay and observed enhanced degranulation and cytokine production (intracellular IFN-γ and TNFα) by NK cells in response to MM cells.

We finally investigated the potential of combining CDK4/6i with daratumumab in a standard 4-h ADCC assays using NK cells from MM patients as effector and MM cell lines as target. Daratumumab-mediated ADCC against MM cells was significantly augmented in the combination compared to single agent.

In conclusion, we here report a novel anti-MM activity of CDK4/6i which is beyond the previously reported growth arrest. The observed ability to directly modulate the immune system along with decrease in the proliferative potential of MM cells may provide opportunities to develop unique combination approaches in MM.

Disclosures: Anderson: Celgene: Membership on an entity's Board of Directors or advisory committees; Millenium-Takeda: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Sanofi-Aventis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Oncopep and C4 Therapeutics.: Other: Scientific Founder of Oncopep and C4 Therapeutics.. Fulciniti: NIH: Research Funding. Munshi: Takeda: Consultancy; Karyopharm: Consultancy; Amgen: Consultancy; AbbVie: Consultancy; Legend: Consultancy; Janssen: Consultancy; Adaptive: Consultancy; BMS: Consultancy; OncoPep: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; C4: Current equity holder in private company.

*signifies non-member of ASH