Joseph G. Jurcic

Severely impaired terminal erythroid differentiation as an independent prognostic marker in myelodysplastic syndromes

Anemia is the defining feature in most patients with myelodysplastic syndromes (MDS), yet defects in erythropoiesis have not been well characterized. We examined freshly obtained bone marrow (BM) samples for stage-specific abnormalities during terminal erythroid differentiation (TED) from 221 samples (MDS, n = 205 from 113 unique patients; normal, n = 16) by measuring the surface expression of glycophorin A, band 3, and integrin α-4. Clinical and biologic associations were sought with presence or absence of TED and the specific stage of erythroid arrest. In 27% of MDS samples (56/205), there was no quantifiable TED documented by surface expression of integrin α-4 and band 3 by terminally differentiating erythroblasts. Absence of quantifiable TED was associated with a significantly worse overall survival (56 vs 103 months, P = .0001) and SRSF2 mutations (7/23, P < .05). In a multivariable Cox proportional hazards regression analysis, absence of TED remained independently significant across International Prognostic Scoring System-Revised (IPSS-R) categories, myeloid/erythroid ratio, and mutations in several genes. In 149/205 MDS samples, the proportion of cells undergoing TED did not follow the expected 1:2:4:8:16 doubling pattern in successive stages. Absence of TED emerged as a powerful independent prognostic marker of poor overall survival across all IPSS-R categories in MDS, and SRSF2 mutations were more frequently associated with absence of TED.

Clinical Studies with Bismuth-213 and Actinium-225 for Hematologic Malignancies

OBJECTIVESnDue to the shorter range and higher linear energy transfer of α-particles compared to β-particles, targeted α-particle therapy may produce more efficient tumor killing while sparing neighboring healthy cells. We will review the clinical studies using α-particle therapy for Acute Myeloid Leukemia (AML).nnnMETHODSnA series of clinical trials were conducted to assess the safety, feasibility, and anti-leukemic effects of lintuzumab, an anti-CD33 humanized monoclonal antibody, labeled with the α-emitters bismuth- 213 (213Bi) and actinium-225 (225Ac).nnnRESULTSnAn initial phase I study conducted in 18 patients with relapsed or refractory AML demonstrated the safety and antitumor effects of 213Bi-lintuzumab. Subsequently, 213Bi-lintuzumab produced remissions in AML patients after partial cytoreduction with cytarabine in phase I/II trial. The 46- minute half-life of 213Bi and need for an onsite generator has limited its utility. Therefore, a secondgeneration construct was developed using 225Ac, a radiometal that yields four α-particle emissions. A phase I trial demonstrated that a single infusion of 225Ac-lintuzumab could be given safely at doses up to 111 kBq/kg with anti-leukemic activity across all dose levels studied. In a second phase I study, 28% of older patients with untreated AML had objective responses after receiving fractionated-dose 225Aclintuzumab and low-dose cytarabine.nnnCONCLUSIONnBased upon the encouraging results seen in phase I trials of 225Ac-lintuzumab, a phase II study of 225Ac-lintuzumab monotherapy for older patients with untreated AML is now in progress and is also being studied in a subset of patients with CD33-positive multiple myeloma.

Abstract B10: A novel high-throughput screen of primary leukemia cells to personalize therapy for relapsed/refractory acute myeloid leukemia (AML): Proof of concept and clinical implementation of precision medicine

Context: For patients with relapsed/refractory AML, therapeutic success is unpredictable with current chemotherapeutic regimens. Moreover, multiple courses of therapy have resulted in co-morbid conditions which can preclude the patient from receiving a potentially curative bone marrow transplant. Objective: In order to identify a successful chemotherapeutic regimen for these patients, we have developed a high-throughput assay that utilizes primary (patient-derived) leukemia cells and tested for chemo-sensitivity and resistance against a panel of FDA approved agents used to treat AML. Design: This assay was developed in 1536 well format and optimized against a panel of leukemia and lymphoma cell lines to determine optimal concentration of cells needed to achieve statistically significant reproducible results. Twelve point dose response curves were performed in duplicate for all agents. Alamar Blue reduction and Annexin V staining were used as indicators of cell viability. Results: Using this assay, we demonstrated in vitro resistance against drugs already clinically administered and importantly showed in vitro sensitivity to agents that had not been previously administered. The index patient was a 32-year-old woman with primary refractory AML who had received six different therapeutic regimens prior to testing, all of which demonstrated in vitro resistance using our assay. The blasts were sensitive, however, to 6-thioguanine with an inhibitory concentration (EC50) of 70 nanoM. Based on the in vitro data, she began a combination treatment regimen containing 6-thioguanine. Following a maintenance regimen, her circulating blast count decreased, and she had partial recovery of the neutrophil count, resulting in a dramatic decrease in the overall leukemia burden. This result was not seen with her previous therapies. After over six months of this therapy, her WBC began to rise and repeat testing indicated resistance to 6-thioguanine with EC50 > 10 microM, confirming the response seen in vivo. We have gone on to test samples from more than twenty-five patients with AML and have accurately predicted the in vivo clinical response (both sensitivity and resistance). In the above case, the treatment regimen identified from the screening results is now being tested in a Phase I clinical trial for patients with relapsed/refractory AML or elderly patients unfit to receive standard AML therapy. In other cases, the treatment regimen identified from the screen provided the needed bridge to allogeneic bone marrow transplantation. Conclusions: These data demonstrate that the technology described here to pharmacologically screen drug therapy for patients with relapsed/refractory AML is both clinically useful and has a role in designing individualized treatment regimens for these patients. Citation Format: David Shum, Ruth Santos, Mark Heaney, Renier Brentjens, Peter Maslak, Todd Rosenblat, Joseph Jurcic, Hakim Djaballah, Mark G. Frattini. A novel high-throughput screen of primary leukemia cells to personalize therapy for relapsed/refractory acute myeloid leukemia (AML): Proof of concept and clinical implementation of precision medicine. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B10.

Abstract A28: Use of a high-throughput screen of primary leukemia cells to personalize therapy for relapsed/refractory AML: Proof of concept and clinical implementation of precision medicine.

Context: For patients with relapsed/refractory AML, therapeutic success is unpredictable with current chemotherapeutic regimens. Moreover, multiple courses of therapy have resulted in co-morbid conditions which can preclude the patient from receiving a bone marrow transplant. Objective: In order to identify a successful chemotherapeutic regimen for these patients, we have developed a high-throughput assay that utilizes primary (patient-derived) leukemia cells and tested for chemo-sensitivity and resistance against a panel of FDA approved agents used to treat AML. Design: This assay was developed in 1536 well format and optimized against a panel of leukemia and lymphoma cell lines to determine optimal concentration of cells needed to achieve statistically significant reproducible results. Twelve point dose response curves were performed in duplicate for all agents. Alamar Blue reduction and Annexin V staining were used as indicators of cell viability. Results: Using this assay, we demonstrated in vitro resistance against drugs already clinically administered and importantly showed in vitro sensitivity to agents that had not been previously administered. The index patient was a 32-year-old woman with primary refractory AML who had received six different therapeutic regimens prior to testing, all of which demonstrated in vitro resistance using our assay. The blasts were sensitive, however, to 6-thioguanine with an inhibitory concentration (EC50) of 70 nanoM. Based on the in vitro data, she began a combination treatment regimen containing 6-thioguanine. Following a maintenance regimen, her circulating blast count decreased, and she had partial recovery of the neutrophil count, resulting in a dramatic decrease in the overall leukemia burden. This result was not seen with her previous therapies. After over six months of this therapy, her WBC began to rise and repeat testing indicated resistance to 6-thioguanine with EC50 > 10 microM, confirming the response seen in vivo. We have gone on to test samples from more than twenty-five patients with AML and have accurately predicted the in vivo clinical response (both sensitivity and resistance) in approximately 90% of cases. In the above case, the treatment regimen identified from the screening results is now being tested in a Phase I clinical trial for patients with relapsed/refractory AML or elderly patients unfit to receive standard AML therapy. In other cases, the treatment regimen identified from the screen provided the needed bridge to allogeneic bone marrow transplantation. Conclusions: These data demonstrate that the technology described here to pharmacologically screen drug therapy for patients with relapsed/refractory AML is both clinically useful and has a role in designing individualized treatment regimens for these patients. Citation Format: David Shum, Mark Heaney, Renier Brentjens, Peter Maslak, Joseph Jurcic, Hakim Djaballah, Mark G. Frattini. Use of a high-throughput screen of primary leukemia cells to personalize therapy for relapsed/refractory AML: Proof of concept and clinical implementation of precision medicine. [abstract]. In: Proceedings of the AACR Special Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(17 Suppl):Abstract nr A28.