ALBERT

Description: Based on the favorable safety profile and the independent activity of rituximab in B-cell lymphoma, we evaluated its efficacy and toxicity after high-dose therapy (HDT) and autologous hematopoietic cell transplantation (HCT). Thirty-five patients with diffuse large cell (25 patients), mantle cell (3 patients), transformed (3 patients), or other (4 patients) subtypes of B-cell lymphoma received HDT followed by a purged autologous graft. The rituximab schedule was 4 weekly infusions (375 mg/m2) starting at day 42 after HCT and, for patients 5 to 35, a second 4-week course 6 months after HCT. All planned therapy was completed in 29 patients. With 30 months' median follow-up, the 2-year event-free survival (EFS) rate was 83% and the overall survival (OS) rate was 88%. For 21 patients with relapsed or refractory large cell lymphoma, the EFS rate was 81% and the OS rate was 85%. Grades 3 to 4 neutropenia occurred in 19 (54%) patients. A prospective study of immune reconstitution included measurements of lymphocyte subsets, immunoglobulins, and response to vaccination. Serious infections were not observed despite delayed B-cell recovery in all patients and suppressed immunoglobulin G (IgG) levels and low pneumococcus antibody titers in a subset. Rituximab after HDT and HCT is feasible, and these phase 2 data support the current US Intergroup phase 3 trial in recurrent/refractory diffuse large cell lymphoma.

Description: The influence of graft composition on clinical outcomes after non-myeloablative allogeneic hematopoietic transplantation is not well characterized. In this report we evaluated the influence of CD34+, CD3+, CD4+, and CD8+ cell doses on donor engraftment, graft-versus-host disease (GVHD), freedom from progression (FFP), and overall survival (OS). Patients (n=63) were given total body irradiation 200 cGy (n=8) or total body irradiation 200 cGy plus fludarabine (n=55) followed by allografting with granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cell (G-PBMC). The median age was 53 years, and donors were HLA-identical siblings (n=38) or HLA-matched unrelated individuals (n=25). Almost all patient were treated for a hematologic malignancy (n=60), with 30 patients (48%) characterized as having advanced diseases. G-PBMC cell doses were prospectively enumerated by FACS analysis at the time of collection. Median donor G-PBMC cell doses were 7.4x106 CD34+/kg (range: 1.9–17.7), 3.2x108 CD3+/kg (range: 0.8–6.4), 2.1x108 CD4+/kg (range: 0.4–4.1), and 1.1x108 CD8+/kg (range: 0.2–3.4). By univariate analysis only G-PBMC CD8+ T-cell dose ≥ the 50th percentile favorably correlated with attainment of full donor blood T-cell chimerism (P = .03). The incidences of grade 2–4 acute GVHD was 16.3% (95% CI: 6.9–25.8) and extensive chronic GVHD was 42.9% (95% CI: 27.8–57.9). No G-PBMC cell dose significantly influenced grade 2–4 acute or extensive chronic GVHD. With a median follow-up of 13 months (range: 5–45), estimates for FFP was 53.7% (95% CI: 37.7–69.7) and OS was 33.4% (95% CI: 17.4–49.4). G-PBMC CD8+ T-cell dose ≥ the 50th percentile T-cell dose was favorably prognostic for both FFP (P = .001) and OS (P = .01). Survival curves for FFP and OS are shown in Figure 1. Extensive chronic GVHD also predicted better FFP (P = .02), but in multivariate analysis only G-PBMC CD8 + T-cell dose (P = .004; RR = 0.2, 95% CI = 0.1–0.6) was associated with improved FFP. Infusion of low G-PBMC CD8+ T-cell dose for non-myeloablative allografting with total body irradiation 200 cGy plus fludarabine may adversely affect donor T-cell engraftment, disease progression and survival outcomes.

Description: Abstract 179 Background: Myeloproliferative neoplasms (MPNs), such as essential thrombocythemia (ET), are driven by neoplastic progenitor cells. The JAK2 V617F mutation can be detected in approximately 50% of patients (pts) with ET, and the JAK2 V617F allele burden can be used to measure the treatment-induced molecular response (MR) over time. Telomerase is upregulated in neoplastic progenitor cells and sustains indefinite replication. Imetelstat is a first in class, potent, specific inhibitor of telomerase which selectively distributes to bone marrow and inhibits thrombopoiesis. In vitro studies demonstrate that imetelstat selectively inhibits spontaneous megakaryocytic colony-forming unit (CFU-Meg) growth from the blood of pts with ET but not from healthy individuals. Phase I studies have demonstrated that imetelstat inhibits telomerase activity in pts at doses of 7.5 mg/kg and above. Therefore, unlike conventional cytoreductive therapy and JAK2 kinase inhibitors, imetelstat may be uniquely able to selectively inhibit proliferation of neoplastic clonogenic cells in pts with ET and modify the biology and progression of the disease. Methods: A phase II study enrolled pts with ET who had failed or were intolerant to at least one prior therapy, or who refused standard therapy. Pts were treated with imetelstat 7.5 mg/kg or 9.4 mg/kg IV weekly. After attainment of best platelet response in the induction phase, maintenance dosing with imetelstat was commenced with dosing based upon platelet count. Primary endpoint was best overall hematologic response (HR) with complete response (CR) defined as platelet count 10%) reached molecular partial responses (PR): one pt after 12 weeks, which has been maintained through 1 year, and 3 other pts at 24, 36 and 48 weeks of therapy. One additional pt with JAK2 V617F levels of 4.8% prior to therapy has also had a 75% reduction after 12 weeks of treatment. A reduction in the spontaneous growth of CFU-Meg was also observed in the 2 pts tested, with 93% and 96% reduction from baseline, respectively. Long-term administration of imetelstat was generally well tolerated. Common adverse events reported on therapy were mild to moderate gastrointestinal toxicities, reductions in neutrophil counts, and fatigue. Conclusions: Imetelstat rapidly induces and maintains hematologic responses in pts with ET who have failed or are intolerant to conventional therapies. Importantly, substantial MR is observed in all JAK2 V617F-positive pts and inhibition of the neoplastic clonogenic growth ex-vivo is demonstrated. The reduction in JAK2 V617F allele burden and cytokine-independent growth of CFU-Meg suggests that imetelstat has a relatively selective inhibitory effect on the growth of the neoplastic clone(s) which drive ET and has the potential to modify the underlying biology of MPNs. Additional data will be presented from this ongoing study. Disclosures: Baerlocher: Geron Corporation: Research Funding. Oppliger Leibundgut:Geron Corporation: Research Funding. Ayran:Geron Corporation: Employment. Blaney:Geron Corporation: Employment. Burington:Geron Corporation: Employment. Morfeld:Geron Corporation: Employment. Odenike:Sanofi Aventis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Reddy:Geron Corporation: Employment. Roeth:Geron Corporation: Research Funding. Stuart:OncoMed Pharmaceuticals: Consultancy; Geron Corporation: Consultancy, Employment.

Description: Background JAK inhibitors, including ruxolitinib, are to date incapable of inducing complete (CR) or partial (PR) remissions, reversal of bone marrow (BM) fibrosis or molecular responses in myelofibrosis (MF). This is consistent with the fact that JAK2 mutations are neither specific nor pathogenetically essential for the disease. Other currently available drugs in MF are equally ineffective in terms of disease-modifying activity. Methods In an investigator-sponsored single-center study (ClinicalTrials.gov Identifier: NCT01731951), imetelstat, a lipid-conjugated oligonucleotide inhibitor of human telomerase, was administered to patients with high or intermediate-2 risk MF (JCO 2011). Adverse events were monitored by common terminology criteria (Version 4.03) and responses by the International Working Group criteria (Blood 2013). Eligibility criteria included platelets ≥50 x 10(9)/L. Study drug and funding were provided by Geron Corporation (Menlo Park, CA, USA). Imetelstat was administered by a 2-hour intravenous infusion (9.4 mg/kg) every three weeks (cohort A) or weekly x 3 followed by every three weeks (cohort B). Mutations with prognostic (ASXL1 and SRSF2) or phenotypic (SF3B1 and U2AF1) relevance were screened by DNA sequencing. Quantitative PCR was used to measure JAK2V617F burden (assay sensitivity 0.01%). Laboratory correlative studies included analyses of granulocyte telomere length, mononuclear cell telomerase activity and human telomerase reverse transcriptase (hTERT) isoforms. Results Thirty-three patients were accrued; the first 18 patients enrolled and followed for a minimum of 3 months or discontinued are presented in this abstract: 11 cohort A and 7 cohort B; 44% PMF, 33% post-PV MF and 22% post-ET MF. Median age was 68 years and baseline risk was high in 56% and intermediate-2 in 44%. Seven patients were transfusion-dependent. Median spleen size was 13 cm and 11 patients had constitutional symptoms. Karyotype was abnormal in 7 patients and 89% were JAK2-mutated. Fifteen (83%) patients were previously treated including 7 with a JAK inhibitor and 3 with pomalidomide. i) Toxicity At a median f/u of 3.2 months, 16 (89%) patients remain on treatment; the two discontinuations were from unrelated death and disease progression. In cohort A, there were no grade-4 treatment-related adverse events; grade-3 events were limited to thrombocytopenia in 27% and anemia in 9%. In cohort B, two (29%) patients experienced grade-4 thrombocytopenia; grade-3 events were limited to thrombocytopenia, neutropenia and anemia in one patient each. Dose reduction was necessary in only two (11%) patients because of grade 3 or 4 myelosuppression. ii) Efficacy Overall response rate was 44%. This included five (28%) patients who met the BM and peripheral blood morphologic criteria for CR (n=4) or PR (n=1) and 3 patients with clinical improvement, pending validation of response duration and resolution of drug-induced grade-1 thrombocytopenia. The four (22%) CR patients experienced reversal of BM fibrosis and recovery of normal megakaryocyte morphology. Two CR patients were transfusion-dependent at baseline and became transfusion-independent. Complete molecular responses were documented in 2 CR patients: one had U2AF1Q157P and 10% JAK2V617F and the other SF3B1K666E and 50% JAK2V617F. A third CR patient had a 〉50% reduction in U2AF1 469_insAGTATG mutation. Among 13 patients with leukocytosis, 10 (77%) normalized their count or had 〉50% reduction. Eleven (61%) patients had complete or partial resolution of leukoerythroblastosis. iii) Laboratory correlative studies Three (50%) of 6 spliceosome-mutated vs. 1 (8%) of 12 unmutated (p=0.045) achieved CR. Spliceosome-mutated patients were also more likely to experience grade-3/4 myelosuppression (67% vs. 25% ; p=0.09). Treatment was associated with suppression of telomerase activity, shortening of telomere length and alteration of hTERT isoform pattern. Conclusions The current study signifies the potential value of telomerase-based treatment strategies in MF and identifies imetelstat as an active drug in that regard. The observed morphologic and molecular remissions confirm selective anti-clonal activity, which has thus far eluded other drugs in MF, including JAK inhibitors. The association between response and spliceosome mutations suggests a broader application for the drug in myeloid malignancies. Disclosures: Stuart: Geron: Consultancy.

Description: This study retrospectively analyzed data from 446 patients given hematopoietic cell transplants from HLA-matched related or unrelated donors after conditioning with 2 Gy total body irradiation with or without fludarabine and postgrafting immunosuppression with mycophenolate mofetil and cyclosporine following grafting. Fifty-three of 446 patients received donor lymphocyte infusion (DLI) with a median CD3 dose of 1 × 107 cells/kg. Their diagnoses included myelodysplastic syndrome (n = 10), acute leukemia (n = 10), chronic leukemia (n = 11), multiple myeloma (n = 9), lymphoma (n = 9), and solid tumors (n = 4). Patients received DLI for persistent disease (n = 8), disease relapse (n = 17), progressive disease (n = 12), low donor chimerism with disease (n = 11), or low chimerism with disease remission (n = 5). Seventeen of the 53 patients (32%) are alive with a median follow-up of 30 months; 5 are in complete remission (CR), 2 are in partial remission (PR), and 10 have stable or progressive disease. Nine of 53 patients (17%) developed grades II to IV acute graft-versus-host disease. Of 48 patients receiving DLI for treatment of disease, 7 achieved CR and 5 PR, with an overall response rate of 25%. Six of 16 patients who received DLI for chimerism had increases in donor chimerism leading to sustained engraftment, whereas 10 eventually rejected their grafts. In conclusion, DLI is a potential treatment strategy, with acceptable toxicity, for patients with persistent, relapsed, or progressive disease after nonmyeloablative hematopoietic cell transplantation.

Description: Although the precise incidence, epidemiology, and impact of human respiratory syncytial virus (HRSV) infection may differ greatly from center to center, there is little debate about the potential for associated morbidity and mortality. We report our approach to infection control and clinical management to reduce the clinical impact of HRSV in our BMT population. An outbreak on our BMT unit was identified in the Winter of 2000–2001. RT-PCR and nucleotide (nt) sequencing of a 270 nt variable region of the HRSV G gene of 6 cases and 12 unrelated community controls was performed. Of the 6 cases, 4 were identified as group A (genotype GA2) and 2 were identified as group B (genotype GB3). Sequences of the GA2 hospital cluster cases were identical as were the 2 hospital case GB3 isolates and the hospital case sequences differed from their respective community controls. These data suggested that there were 2 separate introductions of virus from the community followed by nosocomial spread within the outpatient facility and we were able to direct our infection control efforts and treatment strategies accordingly. An educational campaign was implemented for staff and patients emphasizing the importance of early identification and isolation of patients with HRSV. All patients with either upper (URTI) or lower respiratory tract infection (LRTI) symptoms were isolated and a nasopharyngeal swab for HRSV direct detection and CXR were performed. Post-transplantation, patients with an URTI and a positive swab for HRSV received aerosolized ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide, 6g per day) and 1.5g per kg bodyweight per day of an intravenous immunoglobulin preparation (IVIg) for 3 days. Patients with a positive NP swab and an abnormal CXR or a requirement for supplemental oxygen also received IVIg and ribavirin; however, the treatment was continued until patients no longer required oxygen supplementation. Overall, 3 patients had received autologous and 19 had received allogeneic grafts (14 nonmyeloablative, 5 myeloablative). Steroid administration was not a risk factor for disease. Since the sentinel outbreak, there was a significant decrease in the case attack rates per 10,000 patient days (0.30, 0.27, 0.15, and

Description: Abstract 3843 Background/Aims: Essential thrombocythemia (ET), a clonal myeloproliferative neoplasia, is characterized by elevation of platelets in peripheral blood (PB) and excessive proliferation of megakaryocytes (megs) in bone marrow. Most ET patients exhibit spontaneous growth of megakaryocytic colony-forming units (CFU-Meg) in vitro. One of the most important pathways involved in clonal expansion is reactivation of telomerase, an enzyme complex which is able to compensate for the loss of telomere repeats due to cell divisions. Over 90% of malignancies demonstrate up-regulation of telomerase, which is an essential component for their immortalization. Imetelstat sodium (GRN163L) is a potent and specific telomerase inhibitor that has demonstrated in vitro and in vivo activity against various tumor types and cancer stem cells. Our aims were to study the growth of CFU-Meg and their levels of telomerase activity (TA) from cord blood (CB), mononuclear cells (MNC) from healthy individuals and ET patients, as well as to test whether TA inhibition by imetelstat could suppress CFU-Meg formation. Agents which inhibit clonal expansion in vitro may have promising clinical activity. Methods: CB cells were enriched for CD34 expressing cells using a negative cell separation system. Cells were incubated with imetelstat (1–15μM) in serum free liquid medium, StemSpan® SFEM containing a cytokine formulation designed for the development of meg progenitor cells. CB cells were cultured for a total of 17 days; at various time point cells were enumerated, assessed by flow cytometry for differentiation markers (CD41) and for TA. Mononuclear cells (MNC) from healthy individuals and from 11 ET patients (WHO 2009 criteria) were isolated from PB and suspended in IMDM or plated into collagen ± cytokines (TPO, IL3, IL6, SCF, EPO) and treated with 0, 0.1, 1 and 10 μM imetelstat or a mismatch control, and incubated for several hours (cell suspensions) or 10–12 days (collagen plus 5% CO2) at 37° C. Megs were stained and the number of CFU-Meg was scored. In addition, TA was measured in CD34+ cells, megs and MNC by TRAP assay. Results: TA is low in CD34+ cells from CB of healthy individuals, but increases up to 9 times during early megakaryocytic differentiation (CD41a+CD34-) and peaks at day 3, followed by a decrease as the cells differentiate. Imetelstat (1–15 μM) significantly inhibited TA in a concentration-dependent manner in these progenitor cells (65% to 99%). Despite considerable TA inhibition, no significant inhibition in cellular growth and differentiation of megs was found in these CD34+ cell cultures from healthy CB donors. TA is low in MNC isolated from the PB of healthy individuals and of patients with ET. Imetelstat did not inhibit CFU-Megs in healthy individuals. In contrast, imetelstat significantly (p 〈 0.001) and concentration-dependently inhibited the spontaneous growth of CFU-Meg in each patient with ET (n=11, 7 JAKV617F-positive and 4 JAKV617F-negative). The growth of CFU-Meg (% of control) with various imetelstat concentrations in μM was: 100% (0 μM), 107% ± 8.6% (0.1 μM), 79% ± 11.8% (1 μM) and 33% ± 9.4% (10 μM). No correlation was found with the JAKV617F mutational status, other laboratory and clinical parameters, or with cytoreductive therapies. Conclusions: In summary, we can demonstrate telomerase activation with megakaryocytic proliferation and differentiation which precedes the decrease in cellular proliferation. Furthermore, we demonstrated concentration-dependent inhibition of TA by imetelstat in cells from healthy donors, but without inhibiting megakaryocytic proliferation. In contrast, TA inhibition by imetelstat results in a dose-dependent inhibition of spontaneous growth of CFU-Meg in ET patients. Inhibition was demonstrated at clinically relevant concentrations. This in vitro CFU-Meg inhibition is independent of the JAKV617F mutational status and of cytoreductive therapy. It appears that the transient inhibition of TA in normal megakaryocytic cells by imetelstat does not inhibit cellular proliferation, whereas TA inhibition by imetelstat in malignant cells significantly inhibited CFU-Meg proliferation. These findings suggest a specificity of imetelstat for malignant megakaryocytic cells. The impact of imetelstat's clinical activity is being explored in an ongoing phase 2 study in ET patients who have failed at least one prior therapy or who refuse standard of care. Disclosures: Go: Geron Corporation: Employment. Ninomoto:Geron Corporation: Employment. Kashani:Geron Corporation: Employment. Stuart:Geron Corporation: Employment. Oppliger Leibundgut:Geron Corporation: Service Contract; Novartis: Membership on an entity's Board of Directors or advisory committees, Service Contract; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Baerlocher:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Geron Corporation: Research Funding, Service Contract; Pfizer: Membership on an entity's Board of Directors or advisory committees.

Description: The influence of graft composition on clinical outcomes after reduced-intensity conditioning is not well-characterized. In this report we prospectively enumerated CD34+, CD3+, CD4+, and CD8+ cell doses in granulocyte colony-stimulating factor–mobilized peripheral blood mononuclear cell (G-PBMC) allografts in 63 patients who received transplants following non-myeloablative conditioning with total body irradiation 200 cGy plus fludarabine as treatment for malignant diseases. Donors were HLA-identical siblings (n = 38) or HLA-matched unrelated individuals (n = 25). By univariate analyses G-PBMC CD8+ T-cell dose in at least the 50th percentile favorably correlated with full donor blood T-cell chimerism (P = .03), freedom from progression (P = .001), and overall survival (P = .01). No G-PBMC cell dose influenced grade II to IV acute or extensive chronic graftversus-host disease. In multivariate analysis only G-PBMC CD8+ T-cell dose (P = .003; RR = 0.2, 95% CI = 0.1-0.6) was associated with improved freedom from progression. Infusion of low G-PBMC CD8+ T-cell dose for reduced-intensity allografting may adversely affect T-cell engraftment and survival outcome.

Description: Abstract 4898 Despite improved response rates with the use of novel agents, the vast majority of patients with multiple myeloma (MM) experience disease relapse and progression. This clinical pattern suggests the cells responsible for tumor regrowth persist following treatment, and we previously demonstrated that highly tumorigenic and self-renewing MM cells are relatively resistant to a wide range of anti-myeloma agents. These MM CSCs are present in the peripheral blood circulation and express memory B cell surface antigens (CD19 and CD27) and the stem cell marker aldehyde dehydrogenase (ALDH). We have also studied cellular mechanisms regulating self-renewal and found that MM CSCs express increased levels of telomerase activity (TA). In preclinical models, the novel telomerase inhibitor imetelstat has been found to inhibit CSCs from a wide range of tumor types, and we reported that imetelstat reduced TA in MM CSCs resulting in the loss of self-renewal and clonogenic growth potential. In an open label phase II clinical trial initiated in February 2011, previously treated MM patients (pts) (n=6) with stable but detectable disease following treatment with an iMid or proteasome inhibitor received single agent imetelstat (7.5–9.4 mg/kg IV on days 1 and 8 every 21–28 days). Additional pts (n=4) receiving lenalidomide maintenance and whose disease was stable for at least three months have also been enrolled. Pts received imetelstat therapy until evidence of disease progression or toxicity. Median age is 62.5 years (range 53–68); median number of prior therapies is 1 (range 1–4) including 4 pts with prior autologous transplant and 1 pt with prior mini-allogeneic transplant; 8 pts with prior bortezomib use; 9 pts with prior iMiD use; and 4 pts with concurrent lenalidomide use with receipt of lenalidomide for a median of 11.38 months (range 4.51–19.21 months) prior to initiation of imetelstat. As of July 30, 2012, 6 pts remain on study. Four pts were discontinued from imetelstat therapy after receiving a median of 7 doses of imetelstat either due to disease progression (n=2) or hematologic toxicity (n=2). Cytopenias were the most frequently reported toxicity with 8 of 10 pts demonstrating grade 3–4 thrombocytopenia and neutropenia during cycle 2, often requiring dose reductions or holds in subsequent cycles. The frequency of circulating MM CSCs (CD19+CD27+ALDH+) was quantified by flow cytometry. Circulating MM CSCs could be detected prior to the initiation of imetelstat (mean 10.7 × 10e3 cells/ml, range 17–53 × 10e3) in 8 of the 9 pts who have completed at least 2 cycles of treatment with imetelstat. In the single remaining patient, circulating CSCs were assessed from Cycle 2 onwards. Over the course of treatment, the frequency of MM CSCs decreased significantly, on average 2 fold every 30 days (Fig 1), in 8 of the 9 patients studied despite no upgrades in clinical response as per IWG criteria. In two pts who received 4 and 6 cycles of single agent imetelstat respectively, standard responses detected as decreasing or plateaued serum M protein or light chain levels were sustained over 4 months following discontinuation (Fig 2). Moreover, these delayed responses occurred in the absence of any additional therapy. These findings demonstrate that imetelstat rapidly decreases circulating MM CSCs. In addition, several patients experienced delayed, but sustained, clinical responses as measured by standard criteria. Therefore, imetelstat may have therapeutic implications for MM and other malignancies driven by CSCs. Figure 1. Serial measurement of CSCs in patients (n=9) treated with imetelstat Figure 1. Serial measurement of CSCs in patients (n=9) treated with imetelstat Figure 2. Clinical response in Pts 003 and 004 based on changes in paraprotein level. Dashed line represents off study evaluation. Figure 2. Clinical response in Pts 003 and 004 based on changes in paraprotein level. Dashed line represents off study evaluation. Disclosures: Huff: Celgene: Scientific Advisory Board Other; Novartis: Consultancy. Jones:Cytomedix: Royalties, Royalties Patents & Royalties. Reddy:Geron Corp.: Employment. Nishimoto:Geron Corp: Employment. Stuart:Geron Corp: Consultancy, Employment; OncoMed Pharmaceuticals: Consultancy. Kelsey:Geron Corp: Employment. Matsui:Geron Corp.: Research Funding.