Award Title: Novel approaches to targeting pathogenic megakaryocytes and fibrosis in myelofibrosis
Funder: Cancer Research UK

Abstract: Background  Myeloproliferative neoplasms (MPNs) are bone marrow (BM) malignancies affecting 5-6 per 100,000 individuals/year. Myelofibrosis, the most severe MPN, causes destructive BM fibrosis, severe symptoms, and impaired survival, typically less than 5-10 years following diagnosis. Currently available drug therapies have little impact on fibrosis or survival, and new treatment strategies are urgently required. The key cellular drivers of fibrosis are the megakaryocytes, platelet-producing BM cells that are dramatically increased and over-produce fibrosis-stimulating factors in myelofibrosis.     I recently performed the first comprehensive analysis of haematopoietic stem/progenitor cells (hSPCs) and megakaryocytes from myelofibrosis patients and controls, identifying key cell surface targets and transcriptional regulators for possible therapeutic development. Using a combination of single-cell approaches including simultaneous single-cell mutational analysis/RNA-sequencing, I identified that co-expression of megakaryocyte and stem/progenitor surface antigens selectively identifies malignant-clone derived hSPCs, indicating that bispecific antibody therapies may be an exciting new approach for targeting the malignant clone in MPNs.    Aims  I will focus on cell-surface, cell-intrinsic and cell-extrinsic features of the myelofibrotic BM to identify candidate targets for pre-clinical validation in the following aims:   (1) Identification of candidate HSPC/megakaryocyte cell surface antigens for antibody-based therapeutic targeting;  (2) Determine the molecular drivers of abnormal megakaryocyte development and function in myelofibrosis;  (3) Determine the spatial relationship between megakaryocytes and stromal cells in myelofibrotic bone marrow and the cellular sources of abnormal matrix proteins.   (4) Functionally validate priority targets in vitro and in vivo in patient-derived murine xenografts.      Methods  State-of-the-art, ‘multi-omic’ single-cell approaches and novel imaging platforms will be used including: combined protein/transcriptome profiling using DNA-barcoded antibodies (CITE-Seq/10X Genomics); validating potential molecular drivers of abnormal megakaryopoiesis using forward programming of human pluripotent stem cells for large-scale megakaryocyte generation; imaging mass cytometry to examine cell-matrix interactions, and the MISTRG humanised mouse model to establish patient-derived xenografts.    How the results will be used  My goal is to develop new therapeutic pathways for MPNs focused on the two major unmet treatment needs: specific targeting of the malignant clone and amelioration of BM fibrosis. These strategies would significantly reduce disease progression and improve outcomes for patients with these malignancies.    Collaborating with industry partners in drug discovery and development (Evotec) and immunotherapy (Elstar Therapeutics) will help accelerate translation of research findings to novel therapeutics. Moreover, using single-cell transcriptome and proteome profiling to discover cancer cell-specific drug targets and to gain insight into tumour cell-niche interactions is highly relevant to other blood cancers as well as solid tumours.

Lay Abstract: Background  Myeloproliferative neoplasms (MPNs) are bone marrow (BM) malignancies affecting 5-6 per 100,000 individuals/year. Myelofibrosis, the most severe MPN, causes destructive BM fibrosis, severe symptoms, and impaired survival, typically less than 5-10 years following diagnosis. Currently available drug therapies have little impact on fibrosis or survival, and new treatment strategies are urgently required. The key cellular drivers of fibrosis are the megakaryocytes, platelet-producing BM cells that are dramatically increased and over-produce fibrosis-stimulating factors in myelofibrosis.     I recently performed the first comprehensive analysis of haematopoietic stem/progenitor cells (hSPCs) and megakaryocytes from myelofibrosis patients and controls, identifying key cell surface targets and transcriptional regulators for possible therapeutic development. Using a combination of single-cell approaches including simultaneous single-cell mutational analysis/RNA-sequencing, I identified that co-expression of megakaryocyte and stem/progenitor surface antigens selectively identifies malignant-clone derived hSPCs, indicating that bispecific antibody therapies may be an exciting new approach for targeting the malignant clone in MPNs.    Aims  I will focus on cell-surface, cell-intrinsic and cell-extrinsic features of the myelofibrotic BM to identify candidate targets for pre-clinical validation in the following aims:   (1) Identification of candidate HSPC/megakaryocyte cell surface antigens for antibody-based therapeutic targeting;  (2) Determine the molecular drivers of abnormal megakaryocyte development and function in myelofibrosis;  (3) Determine the spatial relationship between megakaryocytes and stromal cells in myelofibrotic bone marrow and the cellular sources of abnormal matrix proteins.   (4) Functionally validate priority targets in vitro and in vivo in patient-derived murine xenografts.      Methods  State-of-the-art, ‘multi-omic’ single-cell approaches and novel imaging platforms will be used including: combined protein/transcriptome profiling using DNA-barcoded antibodies (CITE-Seq/10X Genomics); validating potential molecular drivers of abnormal megakaryopoiesis using forward programming of human pluripotent stem cells for large-scale megakaryocyte generation; imaging mass cytometry to examine cell-matrix interactions, and the MISTRG humanised mouse model to establish patient-derived xenografts.    How the results will be used  My goal is to develop new therapeutic pathways for MPNs focused on the two major unmet treatment needs: specific targeting of the malignant clone and amelioration of BM fibrosis. These strategies would significantly reduce disease progression and improve outcomes for patients with these malignancies.    Collaborating with industry partners in drug discovery and development (Evotec) and immunotherapy (Elstar Therapeutics) will help accelerate translation of research findings to novel therapeutics. Moreover, using single-cell transcriptome and proteome profiling to discover cancer cell-specific drug targets and to gain insight into tumour cell-niche interactions is highly relevant to other blood cancers as well as solid tumours.

Research Activity Codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS;5.1 PHARMACEUTICALS
Health Categories: CANCER AND NEOPLASMS