Giles, Francis Joseph

Abstract Introduction: Primary myelofibrosis (MF) is a chronic clonal malignancy which is compounded by the presence of inflammation, bone marrow fibrosis/scarring and risk of transformation to acute myeloid leukemia (AML). Ruxolitinib (Rux), a JAK2 inhibitor, is beneficial for reduction of symptoms and splenomegaly, however, significant myelosuppression is also a toxic side effect of this treatment, limiting optimal drug dosage in many patients. 9-ING-41 is a small molecule GSK-3β inhibitor which has significant clinical activity in patients with advanced malignancies and causes no myelosuppression. We thus assessed the effect of 9-ING-41in MF alone or in combination with Rux. We performed ex-vivo colony assays with primary cells from cases with untreated MF along with normal bone marrow (BM). The experiments were designed to assess the effect of drug on the ability of MF stem/progenitor cells to proliferate/differentiate by evaluating the number, size, and the morphology of colonies, both with and without treatment. Methods: Primary peripheral blood mononuclear cells from MF patients and BM from controls were plated in methylcellulose in duplicate, containing cytokines promoting hematopoietic growth, in the presence of either no drug, Rux only (0.05µM), 9-ING-41 only (range: 0.125µM - 10µM), or a combination of 9-ING-41 (range: 0.125µM - 10µM) and Rux (0.05uM). Colonies were counted ten days later, and colony growth frequency, distribution, and morphology were calculated. Results: We observed an increasing presence of large primitive granulocytic/erythroid/macrophage/monocyte (GEMM) colonies proportional to no drug treatment and linear to increasing concentrations of 9-ING-41 in both MF cases relative to other colony types and normal BM, suggestive of a selective primitive proliferative and/or differentiation effect of GSK-3β inhibition on MF hematopoietic progenitor growth. We did not observe this effect in the combinatory treatments (9-ING-41 + Rux), and there was no significant difference on MF colony number or size in colonies grown without treatment or with Rux alone (Figure 1 A/C/E). However, the morphology of the colonies within different treatments was remarkable. In both MF cases, either without treatment or addition of Rux only (0.05µM), the colonies appeared similar to each other -irregular and disorganized relative to normal bone marrow (Figure 1, B/D/F). In the presence of 9-ING-41 alone, we observed morphologically very large, fully differentiated primitive colonies in both MF cases. However, the most striking observation was the comparison of colonies after combination of both inhibitors. These colonies appeared normal and healthy-looking -discreet, round size and similar in morphology to normal bone marrow colonies. Additional studies are currently underway to look at the signaling consequences, including proliferation, differentiation, and cell cycle effect. Our preliminary results suggest this same mechanism might be occurring in MF cases and could explain the selective presence of large differentiated primitive colonies in MF vs. normal BM in the presence of 9-ING-41. Combining 9-ING-41 with Rux may reduce the dose needed for optimal therapeutic response and/or reverse myelosuppression. A Phase 2 study of 9-ING-41 in patients with advanced MF will be conducted. Citation Format: Terra L. Lasho, Francis Giles, Christy Finke, Naseema Gangat, Ayalew Tefferi. 9-ING-41, a GSK-3β-selective small molecule inhibitor, in combination with ruxolitinib in JAK2617F primary myelofibrosis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5217.

3507 Background: Overexpression of GSK-3β, a serine/threonine kinase, is associated with advanced stage malignancies, aggressive tumor growth, and chemotherapy resistance. 9-ING-41 is a GSK-3β inhibitor with significant broad spectrum pre-clinical antitumor activity, including chemotherapy-resistant models. This first-in-human study (NCT03678883) is evaluating the safety, pharmacokinetics (PK), and efficacy of 9-ING-41 monotherapy and in combination with chemotherapy in patients (pts) with refractory malignancies. Methods: 9-ING-41 is given intravenously (IV) twice-weekly as a single-agent (21-day cycle) or combined with gemcitabine, gemcitabine/nab-paclitaxel, carboplatin, carboplatin/paclitaxel, doxorubicin, lomustine or irinotecan in patients previously treated with the same chemotherapy. Results: As of Jan 2020, 101 pts were enrolled. Tumor types: 25 pancreatic (PDAC), 14 colorectal (CRC), 10 non-small cell lung cancer (NSCLC), 8 GBM and other gliomas, 7 melanoma, 5 appendiceal, 4 breast (BC), 30 others. Seven single agent dose levels (DL) completed (1, 2, 3.3, 5, 7, 9.3, 12.4 mg/kg) without any 9-ING-41-attributable SAEs. 9-ING-41 attributable AEs include: transient visual change (color perception; n = 29), starting at DL 3 (3.3mg/kg), all G1/2; infusion reactions (n = 14), all G1/2, starting at DL 5 (7mg/kg). 9-ING-41’s mean terminal half-life is 12-20 hrs. Cmax and AUC0-72, are dose proportional with no accumulation. One BRAFV600K-mutated melanoma with > 20 brain metastases, post checkpoint/BRAF/MEK failure has an ongoing CR starting at cycle 2 and sustained after 9 months on treatment. 32 (31%) pts had SD as best response (6 PDAC, 6 CRC, 3 appendiceal, 2 BC, 2 salivary gland, 2 melanoma, 1 Merkel cell, 2 GBM/glioma, 1 RCC, 1 HCC, 1 NSCLC, 1 esophageal, 1 parotid gland, 1 nasopharyngeal, 1 peritoneal, 1 T cell-ALL). 8 pts remained on study treatment > 5 months (1 melanoma, 3 PDAC, 1 appendiceal, 1 GBM, 1 peritoneal, 1 salivary gland) with median treatment duration of 198 days (range 163-261). 32 pts continue to receive 9-ING-41. Conclusions: 9-ING-41 has dose-proportional PK, is well tolerated with significant antitumor activity as monotherapy and in combination with chemotherapy in pts with refractory tumors. 1 ongoing CR was observed in a refractory BRAF-mutated melanoma. A biologically active dose has been reached, although MTD has not been determined. Enrollment is ongoing. Clinical trial information: NCT03678883 .

Abstract Idiopathic HES is a myeloproliferative disorder (MPD) characterized by persistent overproduction of eosinophils resulting in organ damage. In a small subset of patients (pts), the disease is caused by the FIP1L1-PDGFR-α fusion tyrosine kinase. Its expression has been associated with complete clinical responses to therapy with tyrosine kinase inhibitor (TKI) imatinib mesylate. In contrast, there is no specific therapy for pts with HES lacking FIP1L1-PDGFR-α expression and corticosteroids are used for palliation. Alemtuzumab (Campath-1H™) is a humanized rat monoclonal antibody directed against the CD52 antigen. Since CD52 is expressed on eosinophils, we evaluated its efficacy in pts with FIP1L1-PDGFR-α-negative symptomatic HES. A total of 9 pts (5 male, 4 female) received alemtuzumab in weekly cycles at the dose of 30 (8 pts) or 10 (1 pt) mg 3 times a week intravenously or subcutaneously. During the first week alemtuzumab was given in escalating doses (3→10→30mg) to assure tolerance. Median age was 53 years (range 24–70), time from HES diagnosis to alemtuzumab therapy 34 months (range 4–195), median WBC 17×109/L (range 6.9–82.4), absolute eosinophil count (AEC) 9×109/L (range 0.7–30), and bone marrow eosinophils 23% (range 10–68). Three pts had abnormal cytogenetics: del11(q23), +8, and t(5;6). Pts had received a median of 3 prior therapies (range 2–6), including corticosteroids (prednisone; n=9), imatinib (n=7), dasatinib (n=3), interferon-alpha (n=3), hydroxyurea (n=3), nilotinib (n=2), and cladribine (n=2). A total of 121 weekly cycles have been administered (median 13 cycles) thus far. A complete hematologic response (CHR; i.e. AEC normalization) was observed in 8 pts (89%) within 4 weeks of therapy; peripheral blood eosinophils were undetectable in 6 of 8 CHR pts. Follow-up bone marrow specimens were available in 3 pts while in CHR (after a median of 5.5 weekly alemtuzumab cycles) showing complete response in 2 and partial response in 1 pt. In addition, 3 pts that were on prednisone and 2 on hydroxyurea at the start of alemtuzumab discontinued them within 2 weeks into therapy. One pt had a remarkable partial response with reduction of AEC from 47.5 to 1×109/L after 8 weekly cycles of alemtuzumab; this patient was on 3g of hydroxyurea and 80mg of prednisone at the start of alemtuzumab and was able to discontinue hydroxyurea and decrease prednisone to 10mg while on alemtuzumab. Five pts who stopped alemtuzumab experienced relapse after a median time of 3.5 weeks (range, 1 to 10) and 1 relapsed while receiving alemtuzumab after 14 weekly cycles. Three pts are currently on alemtuzumab: 2 receiving 30 mg weekly as maintenance while in CHR after 8+ and 19+ weeks, respectively, and 1 with partial response is receiving 30mg 3 times a week. One relapsed pt was rechallenged with alemtuzumab and normalized AEC again. Alemtuzumab was generally well tolerated. Grade 3–4 drug-related toxicities occurred in 2 pts, 1 with neutropenia and 1 with infusion-related fever, which led to transient and complete alemtuzumab discontinuation, respectively. Two pts experienced CMV reactivation that required therapy. In summary, alemtuzumab was well tolerated and has remarkable activity in pts with FIP1L1-PDGFR-α-negative HES. Different dose schedules of alemtuzumab that include prolonged maintenance therapy are warranted to improve the response duration. Updated clinical results will be presented.

Abstract The FIP1L1-PDGFR-α fusion kinase induces hypereosinophilic syndrome (HES) in a subset of patients (pts). Imatinib is a potent inhibitor of PDGFR-α and has been associated with durable hematologic responses in pts with HES. However, development of kinase domain mutations may hamper TKI activity, underscoring the need for novel agents to prevent or overcome resistance. We evaluated the efficacy of the novel TKI EXEL-0862 in FIP1L1-PDGFR-α-expressing cells. In 72-hour MTS assay, EXEL-0862 inhibited EOL-1 cell proliferation with an IC50 of 1.0 nM and markedly decreased phosphorylation of STAT3 and Erk1/2, suggesting inhibition of downstream targets of PDGFR-α. More important, EXEL-0862 induced dose-dependent inhibition of PDGFR-α phosphorylation in peripheral blood mononuclear cells from a pt with HES. Exposure of EOL-1 cells to EXEL-0862 10 nM for 24 hours caused apoptosis as evidenced by flow cytometry (annexin-V/PI staining) and transmission electron microscopy. This was coupled with time-dependent cleavage of caspases-3, caspase-9, and PARP and with mitochondrial damage as reflected by cytochrome c translocation into the cytosol, and a diminished mitochondrial transmembrane potential. Of note, apoptotic features were not evident after 16 hours of EXEL-0862 exposure. Immunoblots showed marked downregulation of Mcl-1, but not of Bcl-2, Bcl-XL, or Bax. To elucidate the mechanism of Mcl-1 cleavage, EOL-1 cells were exposed to 10 nM EXEL-0862 for 6 hours followed by cycloheximide (5 μg/ml), a potent translation inhibitor, which resulted in marked Mcl-1 turnover. Treatment with the proteasome inhibitor MG-132 failed to abrogate EXEL-0862-induced Mcl-1 cleavage, suggesting proteasome-independent degradation. Rather, a decrease of pro-form Mcl-1 (p42) and increase of the cleaved Mcl-1 peptide form of Mcl-1 (p28) coincided with caspase-3 activation. Pretreatment with 20 μM pan-caspase inhibitor Z-VAD abolished EXEL-0862-induced Mcl-1 cleavage, pointing to a caspase--dependent mechanism. Collectively, our results establish EXEL-0862 as a solid candidate for the targeted treatment of pts with FIP1L1-PDGFR-α-positive HES.

Abstract Background: We have previously identified Glycogen Synthase Kinase-3 beta (GSK-3β) nuclear accumulation as a hallmark of pancreatic ductal adenocarcinoma (PDAC) and demonstrated the antitumor effects of GSK-3β tool compound inhibitors in vivo (Ougolkov, Clin Cancer Res 2006). 9-ING-41 (Actuate Therapeutics Inc), a first-in-class, small-molecule potent selective GSK-3β inhibitor, has significant preclinical antitumor activity in PDAC. 9-ING-41 is synergistic with gemcitabine (GEM) in significantly reducing PDAC cell proliferation via impairment of ATR/Chk1 DNA damage response (Ding, Clin Cancer Res 2019). These data provided the rationale for inclusion of patients with PDAC in the 1801 phase 1/2 study evaluating 9-ING-41 alone and in combination with chemotherapy, including GEM and GEM plus nab-paclitaxel. Methods: Parts 1 and 2 of the 1801 phase 1/2 study evaluate the safety and tolerability of 9-ING-41 in patients with refractory malignancies. Part 1 establishes the recommended phase 2 study dose (RP2D) for 9-ING-41 monotherapy, while Part 2 assesses 9-ING-41 in combination with chemotherapies. For Part 1, patients received twice-weekly IV infusions of 9-ING-41 (21-day cycle). Based on prior treatment, Part 2 for those with PDAC consists of 9-ING-41 plus GEM (1000 to 1250 mg/m2 days 1 and 8; 21-day cycle) or 9-ING-41 plus GEM and nab-paclitaxel (125 mg/m2). Part 3 (Simon 2-stage phase 2 at the RP2D) will assess clinical benefit in patients with refractory PDAC treated with 9-ING-41-based combinations at the RP2D established in Part 2. Response is defined by response evaluation criteria in solid tumors (RECIST) criteria in evaluable lesions. The study is opening in 25 sites globally and will accrue approximately 300 patients. Results: To date, the study has accrued 34 patients with advanced solid tumors (n=33) or hematologic malignancies (n=1). Four dose levels (1, 2, 3.3, and 5 mg/kg) have been completed without dose-limiting toxicities (DLT). Part 2 of the study evaluating combination of 9-ING-41 with chemotherapy agents has been activated. Six patients with advanced PDAC have enrolled. One patient has completed 5 cycles of treatment with 9-ING-41 (1mg/kg) with stable disease (SD) as the best response. Another patient with SD as the best response has completed 6 cycles and now is joining the arm combining 9-ING-41 with GEM after disease progression. Four additional patients are awaiting first response assessment with enrollment ongoing. 9-ING-41-attributable AE to date are Grade 1 transient visual changes (color perception). Conclusions: 9-ING-41 is well tolerated. Preclinical data support the inclusion of patients with advanced PDAC on clinical studies of 9-ING-41. Citation Format: Benedito A. Carneiro, Malika Dhawan, Brittany Borden, Ludimila Cavalcante, Howard Safran, Andrey Ugolkov, Andrew P. Mazar, Daniel D. Billadeau, Francis J. Giles, Pamela Munster. GSK-3β blockade with 9-ING-41 in pancreas cancer: The 1801 phase 1/2 study [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr B09.

827 Background: 9-ING-41 is a selective GSK-3β inhibitor with significant pre-clinical antitumor activity in a broad spectrum of malignancies as a single agent and in combination with cytotoxic agents. GSK-3β is a serine/threonine kinase whose overexpression is associated with advanced stage, aggressive tumor growth, and chemotherapy resistance. We report the preliminary results of patients (pts) with gastrointestinal (GI) malignancies. Methods: Phase 1b/2 study evaluating safety and efficacy of 9-ING-41 as monotherapy and combination therapy in pts with refractory cancers. 9-ING-41 is administered intravenously twice-weekly as a single agent (21-day-cycle) or combined with chemotherapy agents, including gemcitabine (GEM), nab-paclitaxel + GEM, carboplatin, or paclitaxel. Study parts 1 and 2 evaluate the safety, describe dose-limiting toxicities (DLTs), determine the maximum tolerated dose and the recommended phase 2 study dose (RP2D) for 9-ING-41 as monotherapy (Part 1) and as combination therapy (Part 2). Part 3 (Simon 2-Stage Phase 2) assess clinical benefit in pts treated with 9-ING-41-based combinations at the RP2D established in Part 2. Response is assessed by RECIST 1.1 criteria in the evaluable lesions. Results: To date, the study accrued 63 pts. Five dose levels (1, 2, 3.3, 5 and 7 mg/kg) have been completed without DLTs. Part 2 of the study evaluating 9-ING-41-based chemotherapy combinations is ongoing. Five out of nine pts with pancreas cancer (PCa) enrolled had stable disease (SD) as the best response; 2 out of 9 pts had a 40-45% decline of CA 19-9. One pt completed 6 cycles with 9-ING-41, two pts completed 4 cycles with 9-ING-41/GEM. Two active pts are receiving 9-ING-41/GEM with SD after 3 and 4 cycles. Three out of four pts with adenocarcinoma of the appendix enrolled had SD as the best response; two pts in active treatment are receiving cycles 5 and 6. One out of 13 pts with colorectal cancer had SD. 9-ING-41-attributable AE to date are reversible grade 1 transient visual changes (color perception). Conclusions: 9-ING-41 is well-tolerated with encouraging SD among heavily pretreated pts with carcinoma of the pancreas and appendix. Clinical trial information: NCT03678883.

Abstract Background: The selective AURKA inhibitor alisertib (MLN8237) exhibits disease modifying activity in murine models of myelofibrosis by eradicating atypical megakaryocytes resulting in reduction of marrow fibrosis (Nat Med 2015). Here, we present long term follow-up results from the investigator initiated pilot study of alisertib in patients with myelofibrosis (clinical trials.gov Identifier NCT 02530619). Methods: 24 patients with DIPSS intermediate 1, intermediate-2, or high risk myelofibrosis who were in need of therapy, refractory/intolerant or unlikely to respond to JAK inhibitors with neutrophil count ≥ 1 x109/L, and platelet count ≥ 50 x109/L, received alisertib (provided by Millennium Pharmaceuticals Inc) at a dose of 50 mg twice daily for one week every 21 days. Toxicity assessment was performed by the standard common terminology criteria (Version 4.0). Response was assessed by the international working group for myelofibrosis research and treatment (IWGMRT) criteria. Correlative studies included assessments of JAK2V617F, CALR, and MPL mutant allele burden, degree of fibrosis and GATA1 expression in bone marrow samples obtained pre and post therapy. Results: We enrolled 17 patients with primary myelofibrosis, 4 with post essential thrombocythemia myelofibrosis and 3 with post polycythemia vera myelofibrosis. Median age was 72 years with 66% males. 79% of patients were DIPSS intermediate risk, and the remainder were high risk with 15 patients (62.5%) having received prior JAK inhibitor therapy. Driver mutational status was as follows; 58% JAK2V617F, 29% CALR, and 13% MPL mutated. At study entry, 54% of patients demonstrated palpable splenomegaly ≥ 5 cm below the left costal margin, 54% were transfusion dependent with all patients experiencing constitutional symptoms. At the time of data cut-off, patients received a median of 7.5 cycles (range; 1-29 cycles) of therapy. The 7 patients presently on study have received a median of 23 cycles (range; 8-29 cycles). Reasons for treatment discontinuation included progressive disease/lack of response in 11 (65%) patients, toxicity in 4 (24%) patients and refusal of further therapy in 2 (11%) patients.Safety and Efficacy assessments The most common treatment-emergent grade 3/4 adverse events included neutropenia (42%), thrombocytopenia (29%) and anemia (21%), with 4% each experiencing neutropenic fever, diarrhea, vertigo, elevated creatinine and elevated alanine aminotransferase. 22 patients were considered for response evaluation with 4 of 14 patients (29%) with palpable splenomegaly ≥ 5 cm achieving a spleen response, 1 of 13 patients (8%) becoming transfusion independent, and 5 of 22 patients (23%) experiencing symptom response with ≥ 50% reduction in the MPN-SAF total symptom score. However, when response assessment was restricted to 13 patients who had received a minimum of 5 cycles of therapy, spleen responses were observed in 4 of 7 (57%) patients, 1 of 5 (20%) achieved transfusion independence and 5 of 13 (38%) achieved symptom response. All patients presenting with leukocytosis (n=4) and thrombocytosis (n=2) had resolution with therapy. Of the 7 patients presently on study, four patients continue to demonstrate symptom response, two patients with both spleen and symptom response, and another patient with sustained anemia response. Correlative assessments We compared the intensity of staining of GATA1, a factor that is required for maturation, in sequential bone marrow biopsies from six patients at baseline and after a minimum of five cycles and observed a striking increase in the numbers of GATA1-positive megakaryocytes in five of six cases (Figure 1a). In addition, we observed a one grade reduction in marrow fibrosis in 4 of 6 paired samples (Figure 1b). This reduction in fibrosis was accompanied by sustained responses to the drug. Finally, we compared JAK2, MPL or CALR mutant allele burden in eight paired baseline and cycle 5 or 6 samples and observed decreases in 4 of 8 patients (Figure 1c). Conclusions: Alisertib is safe and well tolerated in patients with myelofibrosis with prolonged administration up to 1.7 years. In addition to providing clinical benefit, alisertib restored normal morphology and GATA1 expression in atypical megakaryocytes and reduced marrow fibrosis and mutant allele burdens. These findings demonstrate that AURKA inhibition should be further explored as a therapeutic option in myelofibrosis. Figure 1. Figure 1. Disclosures Swords: AbbVie: Employment. Watts:Jazz Pharma: Consultancy, Speakers Bureau; Takeda: Research Funding. Frankfurt:Celgene, Jazz, Agios: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees. Altman:Cyclacel: Other: payment to the institution to conduct clinical trial work; Epizyme: Other: payment to the institution to conduct clinical trial work; Ariad: Other: payment to the institution to conduct clinical trial work; Bayer: Other: payment to the institution to conduct clinical trial work; Celator: Other: payment to the institution to conduct clinical trial work; FujiFilm: Other: payment to the institution to conduct clinical trial work; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: payment to the institution to conduct clinical trial work; Agios: Other: Payment to the institution to conduct the trial ; Astellas Pharma: Other; Genetech: Other: Payment to the institution to conduct clinical trial work; Syros: Membership on an entity's Board of Directors or advisory committees; Incyte: Other: payment to the institution to conduct clinical trial work; GSK: Other: payment to the institution to conduct clinical trial work; Immune Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Boeringer Ingelheim: Other: payment to the institution to conduct clinical trial work; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Other: payment to the institution to conduct clinical trial work. Rampal:Celgene: Honoraria; Stemline: Research Funding; Incyte: Honoraria, Research Funding; Constellation: Research Funding; Jazz: Consultancy, Honoraria. Giles:Actuate Therapeutics Inc: Employment, Equity Ownership. Crispino:Forma Therapeutics: Research Funding; Scholar Rock: Research Funding.

Abstract Background: Nilotinib, a 2nd-generation BCR-ABL inhibitor, is 20–30 times more potent than imatinib in vitro. A phase II, open-label study of safety/efficacy of nilotinib in pts with imatinib-resistant/intolerant Ph+ CML-CP or -AP was reported. Planned starting dose was 400mg BID, with escalation to 600mg BID if response was inadequate. The objective of the post-hoc analysis was to evaluate safety/efficacy of nilotinib 600mg BID in CML-CP pts who had dose escalation. Methods: Starting dose was 400mg BID. If response was inadequate (failure to achieve complete hematologic response [CHR] by 3 mos, minimal cytogenetic response [CyR] by 6 mos, or major cytogenetic response [MCyR] by 12 mos; loss of HR, CyR, or progression), nilotinib to 600mg BID dosing was permitted. Imatinib resistance was defined as treatment with imatinib ≥600 mg/d with disease progression (≥50% increase in WBC, blasts, basophils, or platelets) or no HR in peripheral blood and/or bone marrow after 4 wks. Results: Of 320 enrolled pts in CP, 269 remained on nilotinib 400mg BID; 51 pts were dose-escalated to 600mg BID for inadequate responses (mean age 57.7 yrs; 68.6% male). All pts met the study criteria for imatinib resistance. Prior imatinib dose was ≥600mg QD in 98% pts and ≥800 mg QD in 53%. 43/51 (84%) pts had no baseline CHR; 38% had no prior history of complete cytogenetic response (CCyR). 35% had prior MCyR. Median time to dose escalation was 169 (114–211) d. 14 (27.5%) pts remain on therapy; median time to discontinuation from study was 307 (235–414) d. 5 pts with disease progression and no deaths were observed among pts who received 600mg BID. CHR was achieved in 58% of evaluable pts without CHR at baseline (n=43). MCyR occurred in 29% of evaluable pts (15/51) on 600mg BID; 10% (5/51) CCyR. Disease progression was low, occurring in 10% (5/51) of pts on 600mg BID. Median time to progression for CP pts on 600mg BID was 12 mos, substantially less than for pts who stayed on 400mg BID (median not observed yet, at least 20 mo). Nonhematologic AEs in 600mg BID pts were similar to those reported for the entire CP cohort from the phase II study. Grade 3/4 hematologic lab abnormalities were: anemia 13.8%, neutropenia 7.9%, thrombocytopenia 13.7%. Hyperglycemia and elevated bilirubin occurred in 6% and 10% of pts, respectively, on 600mg BID. Conclusions: Some HR and CyR after dose escalation to 600mg BID were observed. Safety/tolerability for 600mg BID were similar to the entire CP cohort. Based on these preliminary data, nilotinib dose escalation to 600mg BID in imatinib-resistant Ph+ CML-CP pts may be effective in pts with inadequate responses to 400mg BID. As might be expected in a more resistant population, response duration was shorter than reported for the phase II CP cohort. Additional follow-up is necessary. Use of 600mg BID is not currently recommended for imatinib-resistant CML-CP pts outside clinical studies.

Abstract Background Systemic mastocytosis (SM) is characterized by abnormal proliferation and accumulation of neoplastic mast cells. Patients (pts) with SM are treated with recombinant interferon-alpha or cladribine. Responses to these agents are poor. Malignant mast cells in SM carry, in most cases, a mutation involving codon 816 of the c-KIT gene (D816V) resulting in constitutively activated c-kit receptor tyrosine kinase believed to be important for disease progression. Agents that antagonize this mutated form of c-kit may have clinical benefit in SM. Dasatinib is one such agent, proven effective in pre-clinical in vitro and in vivo models of SM. Study Design In pilot Phase II trial for SM, Dasatinib was administered at 70mg PO BID. Response was assessed after minimum of 3 months (3 cycles) of therapy. Therapy was discontinued in pts who showed no response after 6 cycles of therapy. Response was evaluated following guidelines proposed by Valent et al. (Leuk Res. 25;603–625, 2001). In addition, all symptoms related to SM were recorded and monitored. Results Thus far, a total of 30 pts have been treated; 24 are evaluable for response and toxicity, including 6 with aggressive SM (ASM), 4 with SM and associated hematologic non-mast cell disease (SM-AHNMD; 2 with chronic myelomonocytic leukemia and one each with myelofibrosis [SM-MF; JAK2 mutation positive and abnormal cytogenetics] and hypereosinophilic syndrome [SM-HES; FIP1L1-PDGFRa negative]) and 14 with indolent SM (ISM) with uncontrolled symptoms despite optimal supportive care measures. Median age is 57 years (range, 35–73); these were 10 males and 14 females; time from diagnosis to dasatinib therapy 49 months (range, 0–233), performance status 1 in 23 and 2 in 1 pt. Eleven patients were previously treated: imatinib mesylate in 6; denileukin diftitox in 4; and erythropoietin, interferon-alpha, or cladribine in 2 each. One pt, who had undergone splenectomy, had hepatomegaly prior to start of therapy. Median Hb 12.4g/dL (range, 8.5–15.4), WBC 6.7×109/L, (range, 3.5–53.3), and platelets 263×109/L (range, 60–377); no patient was transfusion dependent. Percent bone marrow mast cell varied from <10% in 9 pts, to 60% in 4 pts; blood tryptase level was ≤20ng/mL (not significant) in 7 pts and >200ng/mL (upper limit of the test) in 7 pts. A total of 94 cycles of therapy were administered. The median number of cycles was 4 (range, 1–8). Ten patients stopped therapy: 1 due to progression of AHNMD to acute leukemia, 1 lost a response (symptomatic improvement), 2 had no response after 3 months of therapy, and 6 due to toxicity. No grade 4 toxicity was observed. Twelve patients decreased the dose of dasatinib to 50mg PO BID, of which four to 40mg PO BID. Two patients (8%) achieved complete remission, one with SM-MF, and one with SM-HES. Both were c-KIT mutation negative and had low, not significant tryptase levels. Both were anemic (Hb 9.4g/dL) and failed erythropoietin therapy, and had abnormal WBC differential; one had low platelets (90×109/L). No significant response in % bone marrow mast cells (4 pts are too early in therapy) or blood tryptase levels have been observed in other patients so far. Symptoms related to SM improved significantly in 7 patients (29%). Conclusion Dasatinib is active in SM (overall response rate 37%). Updated clinical and molecular results will be presented.

Abstract Abstract 750 Background: DKK1 is a negative regulator of the Wnt signaling pathway in bone that is overexpressed in a subset of newly-diagnosed MM patients with osteolytic lesions as well as in refractory and relapsed patients. Expression also correlates with the number of osteolytic lesions in untreated MM patients. BHQ880 is a novel anti-DKK1 human monoclonal antibody. Alleviation of DKK1 inhibition by BHQ880 results in activation of the Wnt signaling pathway, leading to increased bone mass mediated via upregulation of osteoblasts in mice and monkeys. In murine models of MM bone disease; this anabolic activity of BHQ880 increased trabecular and cortical bone density. Lytic bone disease in MM is caused by osteoclast activation and osteoblast inhibition. Current approved therapies for the treatment of MM bone disease are focused on osteoclast inhibition (e.g., bisphosphonates) and BHQ880 therapy may be able to reverse the effects of DKK1-induced osteoblast inhibition. Therefore, dual therapy with zoledronic acid to decrease bone resorption and BHQ880 to increase new bone formation may provide an effective treatment strategy for MM bone disease. Methods: In the phase I portion of this phase I/II study, patients with relapsed or refractory MM with prior skeletal-related event (SRE) were treated with BHQ880 as an IV infusion Q28 days. Patients also received Zol (4 mg) and approved MM Tx (bortezomib not allowed). Bone markers and total DKK1 levels along with bone mineral density are being measured. Full PK profiles were collected during the first and second cycle, after which predose (trough) samples were collected to assess accumulation. Results: Ten pts (6:M, 4:F), median age: 66.5 yrs (range 41- 70), performance status-0(5 pts), 1(4 pts), 2 (1 pts) have been enrolled in the following dose levels (mg/kg) 3 (2 pts), 10 (starting dose level -4 pts), 20 (4 pts) and have been on treatment for 1 day to 5 28-day cycles. No BHQ880-related AE's have been observed to date. Bone mineral density (BMD) data from the first two patients treated at 10 mg show the following: a.) Pt 1 (hip +5.8%, spine N/A due to surgery, wrist -1.8%); b.) Pt 2 (hip -0.2%, spine +6.1%, wrist not done). The biomarker data from these patients show: a.) Pt 1 shows a maximal +98% change over baseline in PINP at day 15 post-treatment, while osteocalcin (OC) changes +17% at day 15, reaching a +56% change over baseline at cycle 4 day 1; uNTx/Cr changes – 43 % at cycle 2 day 15. b) Partial data from Pt 2 suggests a -44 % change in PINP and –73 % change in OC and a +73% change in uNTx/Cr. Baseline total DKK1 levels on 3 patients ranged from 8.8 to 21.5 ng/mL. Preliminary PK analysis is available in 1 out of 3 patients treated at 10mg/kg. The Cmax achieved after the first infusion was 165 ug/mL and 201 ug/mL after the second infusion. Calculated t1/2 was 188 hours after the first infusion and 254 hours after the second infusion. Regarding overall exposure, AUC0-672 hours after first infusion was 36081 hr*ng/mL and 48533 hr*ng/mL after the second infusion. Conclusion: BHQ880 given IV Q28 days appears to be well tolerated in combination with Zol and chosen MM Tx. Once safety of 40 mg/kg BHQ880 or the MTD dose has been determined, pts will be enrolled in the phase II portion to assess activity on a SRE endpoint. Updated safety, efficacy, bone density and biomarker data will be presented on all patients at the upcoming ASH meeting. Disclosures: Padmanabhan: Genentech: Consultancy, Honoraria; GSK: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau. Off Label Use: BHQ880, a novel osteoblast activating, anti-DKK1 antibody. Dzik-Jurasz:Novartis: Employment, Equity Ownership. Gangolli:Novartis: Employment, Equity Ownership. Ettenberg:Novartis: Employment, Equity Ownership. Miner:Novartis: Employment, Equity Ownership. Bilic:Novartis: Employment, Equity Ownership. Whyte:Novartis: Employment, Equity Ownership. Mehdi:Novartis: Employment, Equity Ownership. Chiang:Novartis: Employment, Equity Ownership. Rae:Novartis: Employment, Equity Ownership. Shah:Novartis: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Millenium: Research Funding, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Elan: Consultancy. Giles:Novartis: Consultancy, Research Funding; BMS: Research Funding; Merck: Research Funding; Clavis: Research Funding. Stewart:Novartis: Consultancy; Amgen: Consultancy; Millenium: Consultancy, Research Funding; Proteolix: Consultancy; Celgene: Honoraria.