Oncogenic signaling by the Philadelphia chromosome-encoded BCR-ABL fusion kinase initiates and drives both Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myelogenous leukemia (CML). Food and Drug Administration (FDA)- approved BCR-ABL-specific kinase inhibitors (BCR-ABL–KIs) imatinib, dasatinib and nilotinib induce prolonged remissions in CML but poor leukemia-reduction and relapse-control in Ph+ ALL. The relative primary BCR-ABL–KI-resistance in Ph+ ALL patients carrying predominantly BCR-ABLWT disease cannot be attributed to drug-resistant BCR-ABL mutations (BCR-ABLMUTANTS), and remains poorly understood.
We established a cell-based platform to evaluate the modulation of anti-Ph+ ALL activity of drugs by both tumor-extrinsic cytokines normally present in the leukemia microenvironment and tumor-intrinsic vector-mediated alteration of candidate genes. We identified that BCR-ABLWT-driven Ph+ ALL cells are rendered significantly resistant against all FDAapproved BCR-ABL–KIs by 1) Several host-cytokines, but most dominantly by Interleukin7 (IL7), and 2) Cell-intrinsic functional-loss of IKAROS. Utilizing IL7-deficient recipient mice, we demonstrated that physiological levels of IL7 significantly attenuate the survival benefit derived from dasatinib monotherapy against Ph+ ALL. Follow-up mechanistic studies using cell signaling and gene expression comparisons indicated that IL7 imparts chemo-refractoriness by initiating IL7-pSTAT5-c-MYC signaling. Interestingly, IKAROS haploinsufficiency, which has been previously associated with poor clinical prognosis in patients with Ph+ ALL, was recently demonstrated to directly de-repress c-MYC expression. This suggested that both cell-extrinsic IL7 and cell-intrinsic IKAROS loss converge on c-MYC, which may act as node of leukemia BCR-ABL–KI-refractoriness. We confirmed that vector-mediated modifications imitating IL7 induction of STAT5 activity, functional-loss of IKAROS, and c-MYC over-expression, all selectively enrich Ph+ ALL cells during prolonged exposures to imatinib and dasatinib, thus revealing new chemo-refractory phenotypes.
Contemporary medicine advocates co-treatment with agents of complementary mechanism of drug-action to tackle drug resistance. To identify combination agents that could overcome the dasatinib-resistant phenotypes of Ph+ ALL, we screened a library of 3200 agents including known anti-infective and chemotherapy drugs. We discovered that a well known antimalarial drug dihydroartemisinin (DHA) killed host-IL7-protected BCR-ABLWT, c-MYC-overexpressing BCR-ABLWT and BCR-ABLMUTANT Ph+ ALL cells in vitro. In vivo, DHA displayed weak activity as a single agent but its addition synergistically augmented the leukemia reduction by dasatinib, relative to either of the two drugs alone. Remarkably, DHA and dasatinib combination regimen eliminated host-protected dasatinib-refractory persistent leukemia and improved long-term survival from 0 to >90% in a murine model that faithfully captures the BCR-ABL–KI drug-refractoriness of human Ph+ ALL.
This study: 1) Uncovers novel mechanisms of clinical drug-resistance against BCR-ABL–KIs, 2) Identifies increased levels of IL7, pSTAT5 and c-MYC protein, and IKAROS haploinsufficiency as potential biomarkers of BCR-ABL-targeted drug-resistance, 3) Strongly supports clinical exploration of the BCR-ABL–KI and DHA combinations for treating patients with Ph+ ALL, and 4) Establishes a paradigm for investigating frequently overlooked host-tumor-drug interactions.
","abstract_html":"<p>Oncogenic signaling by the Philadelphia chromosome-encoded BCR-ABL fusion kinase initiates and drives both Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myelogenous leukemia (CML). Food and Drug Administration (FDA)- approved BCR-ABL-specific kinase inhibitors (BCR-ABL–KIs) imatinib, dasatinib and nilotinib induce prolonged remissions in CML but poor leukemia-reduction and relapse-control in Ph+ ALL. The relative primary BCR-ABL–KI-resistance in Ph+ ALL patients carrying predominantly BCR-ABLWT disease cannot be attributed to drug-resistant BCR-ABL mutations (BCR-ABLMUTANTS), and remains poorly understood.</p> <p>We established a cell-based platform to evaluate the modulation of anti-Ph+ ALL activity of drugs by both tumor-extrinsic cytokines normally present in the leukemia microenvironment and tumor-intrinsic vector-mediated alteration of candidate genes. We identified that BCR-ABLWT-driven Ph+ ALL cells are rendered significantly resistant against all FDAapproved BCR-ABL–KIs by 1) Several host-cytokines, but most dominantly by Interleukin7 (IL7), and 2) Cell-intrinsic functional-loss of IKAROS. Utilizing IL7-deficient recipient mice, we demonstrated that physiological levels of IL7 significantly attenuate the survival benefit derived from dasatinib monotherapy against Ph+ ALL. Follow-up mechanistic studies using cell signaling and gene expression comparisons indicated that IL7 imparts chemo-refractoriness by initiating IL7-pSTAT5-c-MYC signaling. Interestingly, IKAROS haploinsufficiency, which has been previously associated with poor clinical prognosis in patients with Ph+ ALL, was recently demonstrated to directly de-repress c-MYC expression. This suggested that both cell-extrinsic IL7 and cell-intrinsic IKAROS loss converge on c-MYC, which may act as node of leukemia BCR-ABL–KI-refractoriness. We confirmed that vector-mediated modifications imitating IL7 induction of STAT5 activity, functional-loss of IKAROS, and c-MYC over-expression, all selectively enrich Ph+ ALL cells during prolonged exposures to imatinib and dasatinib, thus revealing new chemo-refractory phenotypes.</p> <p>Contemporary medicine advocates co-treatment with agents of complementary mechanism of drug-action to tackle drug resistance. To identify combination agents that could overcome the dasatinib-resistant phenotypes of Ph+ ALL, we screened a library of 3200 agents including known anti-infective and chemotherapy drugs. We discovered that a well known antimalarial drug dihydroartemisinin (DHA) killed host-IL7-protected BCR-ABLWT, c-MYC-overexpressing BCR-ABLWT and BCR-ABLMUTANT Ph+ ALL cells in vitro. In vivo, DHA displayed weak activity as a single agent but its addition synergistically augmented the leukemia reduction by dasatinib, relative to either of the two drugs alone. Remarkably, DHA and dasatinib combination regimen eliminated host-protected dasatinib-refractory persistent leukemia and improved long-term survival from 0 to >90% in a murine model that faithfully captures the BCR-ABL–KI drug-refractoriness of human Ph+ ALL.</p> <p>This study: 1) Uncovers novel mechanisms of clinical drug-resistance against BCR-ABL–KIs, 2) Identifies increased levels of IL7, pSTAT5 and c-MYC protein, and IKAROS haploinsufficiency as potential biomarkers of BCR-ABL-targeted drug-resistance, 3) Strongly supports clinical exploration of the BCR-ABL–KI and DHA combinations for treating patients with Ph+ ALL, and 4) Establishes a paradigm for investigating frequently overlooked host-tumor-drug interactions.</p>","abstract_has_math":false,"creators":["Singh, Harpreet"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Biomedical Sciences","degree_department":null,"school":null,"contributors":["Gerard P. Zambetti, Ph.D. (for Richard T. Williams, M.D., Ph.D.)"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-08-01T07:00:00Z","date_published":"2012-08-01T07:00:00Z","updated_at":"2026-07-24T05:00:17Z","subjects":["High Throughput Drug Screening","Tumor Microenvironment","Ph+ Acute Lymphoblastic Leukemia","BCR-ABL Kinase Inhibitors","Dasatinib","Dihydroartemisinin","Chemicals and Drugs","Diseases","Medical Sciences","Medicine and Health Sciences","Neoplasms","Pharmaceutical Preparations","Pharmaceutics and Drug Design","Pharmacy and Pharmaceutical Sciences"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://dc.uthsc.edu/dissertations/249","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Gerard P. Zambetti, Ph.D. (for Richard T. Williams, M.D., Ph.D.)"]},{"key":"dc:creator","label":"Author","values":["Singh, Harpreet"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2016-06-15T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biomedical Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["High Throughput Drug Screening","Tumor Microenvironment","Ph+ Acute Lymphoblastic Leukemia","BCR-ABL Kinase Inhibitors","Dasatinib","Dihydroartemisinin","Chemicals and Drugs","Diseases","Medical Sciences","Medicine and Health Sciences","Neoplasms","Pharmaceutical Preparations","Pharmaceutics and Drug Design","Pharmacy and Pharmaceutical Sciences"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://dc.uthsc.edu/dissertations/249"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Oncogenic signaling by the Philadelphia chromosome-encoded BCR-ABL fusion kinase initiates and drives both Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myelogenous leukemia (CML). Food and Drug Administration (FDA)- approved BCR-ABL-specific kinase inhibitors (BCR-ABL–KIs) imatinib, dasatinib and nilotinib induce prolonged remissions in CML but poor leukemia-reduction and relapse-control in Ph+ ALL. The relative primary BCR-ABL–KI-resistance in Ph+ ALL patients carrying predominantly BCR-ABLWT disease cannot be attributed to drug-resistant BCR-ABL mutations (BCR-ABLMUTANTS), and remains poorly understood.
We established a cell-based platform to evaluate the modulation of anti-Ph+ ALL activity of drugs by both tumor-extrinsic cytokines normally present in the leukemia microenvironment and tumor-intrinsic vector-mediated alteration of candidate genes. We identified that BCR-ABLWT-driven Ph+ ALL cells are rendered significantly resistant against all FDAapproved BCR-ABL–KIs by 1) Several host-cytokines, but most dominantly by Interleukin7 (IL7), and 2) Cell-intrinsic functional-loss of IKAROS. Utilizing IL7-deficient recipient mice, we demonstrated that physiological levels of IL7 significantly attenuate the survival benefit derived from dasatinib monotherapy against Ph+ ALL. Follow-up mechanistic studies using cell signaling and gene expression comparisons indicated that IL7 imparts chemo-refractoriness by initiating IL7-pSTAT5-c-MYC signaling. Interestingly, IKAROS haploinsufficiency, which has been previously associated with poor clinical prognosis in patients with Ph+ ALL, was recently demonstrated to directly de-repress c-MYC expression. This suggested that both cell-extrinsic IL7 and cell-intrinsic IKAROS loss converge on c-MYC, which may act as node of leukemia BCR-ABL–KI-refractoriness. We confirmed that vector-mediated modifications imitating IL7 induction of STAT5 activity, functional-loss of IKAROS, and c-MYC over-expression, all selectively enrich Ph+ ALL cells during prolonged exposures to imatinib and dasatinib, thus revealing new chemo-refractory phenotypes.
Contemporary medicine advocates co-treatment with agents of complementary mechanism of drug-action to tackle drug resistance. To identify combination agents that could overcome the dasatinib-resistant phenotypes of Ph+ ALL, we screened a library of 3200 agents including known anti-infective and chemotherapy drugs. We discovered that a well known antimalarial drug dihydroartemisinin (DHA) killed host-IL7-protected BCR-ABLWT, c-MYC-overexpressing BCR-ABLWT and BCR-ABLMUTANT Ph+ ALL cells in vitro. In vivo, DHA displayed weak activity as a single agent but its addition synergistically augmented the leukemia reduction by dasatinib, relative to either of the two drugs alone. Remarkably, DHA and dasatinib combination regimen eliminated host-protected dasatinib-refractory persistent leukemia and improved long-term survival from 0 to >90% in a murine model that faithfully captures the BCR-ABL–KI drug-refractoriness of human Ph+ ALL.
This study: 1) Uncovers novel mechanisms of clinical drug-resistance against BCR-ABL–KIs, 2) Identifies increased levels of IL7, pSTAT5 and c-MYC protein, and IKAROS haploinsufficiency as potential biomarkers of BCR-ABL-targeted drug-resistance, 3) Strongly supports clinical exploration of the BCR-ABL–KI and DHA combinations for treating patients with Ph+ ALL, and 4) Establishes a paradigm for investigating frequently overlooked host-tumor-drug interactions.
"]},{"key":"dc:title","label":"Title","values":["Discovery of Dihydroartemisinin and Dasatinib Drug Combination to Cure Pooroutcome BCR-ABL+ Acute Lymphoblastic Leukemia"]}]}],"canonical_facts":{"dc:contributor":["Gerard P. Zambetti, Ph.D. (for Richard T. Williams, M.D., Ph.D.)"],"dc:creator":["Singh, Harpreet"],"dc:date.available":["2016-06-15T07:00:00Z"],"dc:description.abstract":["Oncogenic signaling by the Philadelphia chromosome-encoded BCR-ABL fusion kinase initiates and drives both Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myelogenous leukemia (CML). Food and Drug Administration (FDA)- approved BCR-ABL-specific kinase inhibitors (BCR-ABL–KIs) imatinib, dasatinib and nilotinib induce prolonged remissions in CML but poor leukemia-reduction and relapse-control in Ph+ ALL. The relative primary BCR-ABL–KI-resistance in Ph+ ALL patients carrying predominantly BCR-ABLWT disease cannot be attributed to drug-resistant BCR-ABL mutations (BCR-ABLMUTANTS), and remains poorly understood.
We established a cell-based platform to evaluate the modulation of anti-Ph+ ALL activity of drugs by both tumor-extrinsic cytokines normally present in the leukemia microenvironment and tumor-intrinsic vector-mediated alteration of candidate genes. We identified that BCR-ABLWT-driven Ph+ ALL cells are rendered significantly resistant against all FDAapproved BCR-ABL–KIs by 1) Several host-cytokines, but most dominantly by Interleukin7 (IL7), and 2) Cell-intrinsic functional-loss of IKAROS. Utilizing IL7-deficient recipient mice, we demonstrated that physiological levels of IL7 significantly attenuate the survival benefit derived from dasatinib monotherapy against Ph+ ALL. Follow-up mechanistic studies using cell signaling and gene expression comparisons indicated that IL7 imparts chemo-refractoriness by initiating IL7-pSTAT5-c-MYC signaling. Interestingly, IKAROS haploinsufficiency, which has been previously associated with poor clinical prognosis in patients with Ph+ ALL, was recently demonstrated to directly de-repress c-MYC expression. This suggested that both cell-extrinsic IL7 and cell-intrinsic IKAROS loss converge on c-MYC, which may act as node of leukemia BCR-ABL–KI-refractoriness. We confirmed that vector-mediated modifications imitating IL7 induction of STAT5 activity, functional-loss of IKAROS, and c-MYC over-expression, all selectively enrich Ph+ ALL cells during prolonged exposures to imatinib and dasatinib, thus revealing new chemo-refractory phenotypes.
Contemporary medicine advocates co-treatment with agents of complementary mechanism of drug-action to tackle drug resistance. To identify combination agents that could overcome the dasatinib-resistant phenotypes of Ph+ ALL, we screened a library of 3200 agents including known anti-infective and chemotherapy drugs. We discovered that a well known antimalarial drug dihydroartemisinin (DHA) killed host-IL7-protected BCR-ABLWT, c-MYC-overexpressing BCR-ABLWT and BCR-ABLMUTANT Ph+ ALL cells in vitro. In vivo, DHA displayed weak activity as a single agent but its addition synergistically augmented the leukemia reduction by dasatinib, relative to either of the two drugs alone. Remarkably, DHA and dasatinib combination regimen eliminated host-protected dasatinib-refractory persistent leukemia and improved long-term survival from 0 to >90% in a murine model that faithfully captures the BCR-ABL–KI drug-refractoriness of human Ph+ ALL.
This study: 1) Uncovers novel mechanisms of clinical drug-resistance against BCR-ABL–KIs, 2) Identifies increased levels of IL7, pSTAT5 and c-MYC protein, and IKAROS haploinsufficiency as potential biomarkers of BCR-ABL-targeted drug-resistance, 3) Strongly supports clinical exploration of the BCR-ABL–KI and DHA combinations for treating patients with Ph+ ALL, and 4) Establishes a paradigm for investigating frequently overlooked host-tumor-drug interactions.
"],"dc:identifier":["https://dc.uthsc.edu/dissertations/249"],"dc:subject":["High Throughput Drug Screening","Tumor Microenvironment","Ph+ Acute Lymphoblastic Leukemia","BCR-ABL Kinase Inhibitors","Dasatinib","Dihydroartemisinin","Chemicals and Drugs","Diseases","Medical Sciences","Medicine and Health Sciences","Neoplasms","Pharmaceutical Preparations","Pharmaceutics and Drug Design","Pharmacy and Pharmaceutical Sciences"],"dc:title":["Discovery of Dihydroartemisinin and Dasatinib Drug Combination to Cure Pooroutcome BCR-ABL+ Acute Lymphoblastic Leukemia"],"thesis:degree_discipline":["Biomedical Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T05:00:17Z"}