Oblimersen Sodium Research Articles

A phase I study of G3139 in combination with RICE chemotherapy in relapsed non-Hodgkin’s lymphoma (NHL)

17529 Background: Aggressive lymphomas are chemosensitive, but frequently relapse. Bcl-2 protein overexpression promotes tumor cell survival via anti-apoptosis, and is clinically correlated with shortened remission duration and decreased survival. The antisense oligonucleotide oblimersen sodium (G3139) downregulates bcl-2, has activity in NHL, and may be synergistic with chemotherapy. Methods: Pts had histologically confirmed aggressive NHL that relapsed after one prior anthracycline-based regimen. G3139 was given as a continuous infusion on Days 1–8 (168 hours) every 14 days, with stem cell collection following cycle 3. Standard RICE chemotherapy was given on Days 4–6, allowing 72 hrs pre- and 48 hrs post-chemo G3139. Dose-limiting toxicity (DLT) was defined as grade 3 or greater non-hematologic toxicity, grade 4 thrombocytopenia, duration of neutropenia <500/mL greater than 7 days despite growth factors, grade 3 hemolytic anemia, or prolonged severe anemia. Pharmacodynamic endpoints included measurement of bcl-2 protein in peripheral blood (FACS analysis) and tumor (IHC), and bcl-2 RT-PCR in blood and tumor. Results: 8 pts were enrolled. At dose level 1 (G3139 3 mg/kg/day), both enrolled pts had grade 4 thrombocytopenia. The next 6 patients were treated with G3139 2.5 mg/kg/day (Dose Level -1) without any DLT’s. There were no grade 3 or 4 non-hematologic toxicities. 7 evaluable pts had successful stem cell collections: median CD34+ 4.2 × 106/kg (range, 1.3–8.72 × 106/kg). Responses: 4 CR/CRu, 2 PR, 1 SD, 1 too early. There was no detectable decrease in bcl-2 protein in the blood using flow cytometry or RT-PCR. Conclusion: The maximum tolerated dose of G3139 given over 8 days in combination with RICE chemotherapy is 2.5 mg/kg/day. It is unlikely that this dose sufficiently suppresses bcl-2 levels. The protocol will thus be amended to shorten the G3139 infusion to 5 days with renewed efforts to escalate the dose. No significant financial relationships to disclose.

A Phase II study of Bcl-2 antisense (oblimersen sodium) combined with gemtuzumab ozogamicin in older patients with acute myeloid leukemia in first relapse

Oblimersen selectively targets Bcl-2 mRNA and has been shown to enhance the apoptotic activity of various antileukemic agents, including gemtuzumab ozogamicin (GO), in preclinical studies. We evaluated the efficacy and safety of oblimersen combined with GO in patients ≥60 years of age in first relapse with CD33+ acute myeloid leukemia. Oblimersen 7 mg/kg/day was given as a continuous intravenous infusion on days 1–7 and 15–21. GO 9 mg/m 2 was given intravenously on days 4 and 18. Twelve of 48 patients (25%) achieved a major response (five, complete response and seven, complete response without platelet recovery). Ten of the 12 patients who achieved a major response survived >6 months compared with six of 36 non-responders. Serious adverse events for the oblimersen/GO combination were qualitatively similar to those reported for GO alone. Oblimersen can be safely combined with GO. Assessment of incremental benefit will require a randomized trial.

Mechanisms Underlying the Development of Androgen-Independent Prostate Cancer

Prostate cancer continues to be the most common lethal malignancy diagnosed in American men and the second leading cause of male cancer mortality. The American Cancer Society estimates that during 2005, ∼232,090 new cases of prostate cancer will be diagnosed in the United States and 30,350 men

A phase I, pharmacokinetic and biologic correlative study of oblimersen sodium (Genasense™, G3139) and irinotecan in patients with metastatic colorectal cancer

Purpose: To assess the feasibility and antitumor activity of oblimersen sodium, an antisense oligonucleotide directed to the Bcl-2 mRNA, combined with irinotecan in patients with advanced colorectal carcinoma, characterize the pharmacokinetic behavior of both oblimersen sodium and irinotecan, and examine Bcl-2 protein inhibition in peripheral blood mononuclear cells (PBMC).Patients and methods: Patients were treated with escalating doses of oblimersen sodium administered by continuous intravenous infusion (CIVI) days 1–8, and irinotecan administered intravenously on day 6 once every 3 weeks.Results: Twenty patients received a total of 84 courses at doses ranging from 3 to 7mg/kg/day for oblimersen sodium and from 280 to 350mg/m2 for irinotecan. Febrile neutropenia and diarrhea limited escalation of oblimersen sodium and irinotecan to 5mg/kg/day and 350mg/m2, respectively. Other toxicities included nausea, vomiting, fever and fatigue. Steady-state plasma concentrations were achieved within 48h of beginning oblimersen sodium treatment and the agent was undetectable 24h after the discontinuation of the infusion. Reduction in levels of Bcl-2 protein in PBMC was documented following treatment with oblimersen sodium. One patient experienced a partial response and 10 additional patients had stable disease lasting 2.5–10 months.Conclusions: The combination is well tolerated at the recommended phase II oblimersen sodium dose of 7mg/kg/day CIVI days 1–8 with irinotecan 280mg/m2 intravenously on day 6 every 3 weeks.

Efficacy and Safety of the Combination of Genasense™ (Oblimersen Sodium, Bcl-2 Antisense Oligonucleotide), Fludarabine and Rituximab in Previously Treated and Untreated Subjects with Chronic Lymphocytic Leukemia.

Bcl-2 is an anti-apoptotic protein closely linked to chemotherapy resistance and inferior survival in patients (pts) with CLL. Genasense (G) enhances apoptosis induced by fludarabine (F), dexamethasone, and rituximab (R) in vitro. Despite limited single-agent activity in heavily pre-treated CLL pts, G significantly increased the rate of durable complete responses (CR) in combination with fludarabine (F) and cyclophosphamide in relapsed or refractory CLL (Rai, ASH 2004). Down-regulation of Bcl-2 sensitizes CLL cells to apoptosis induced by F and R. In order to examine the impact of G on the FR combination, we initiated a phase II study of the combination of FRG in pts with either previously untreated (UT) or relapsed, previously treated (PT) CLL who require systemic treatment. Eligibility includes: plts ≥ 50,000/mm3; serum Cr ≤ 1.5 mg/dL; adequate organ function; negative Coombs; no history of autoimmune hemolytic anemia. In cycle 1, G is given by continuous intravenous infusion at 1.5 mg/kg/d days 1 to 7. R is given in a dose-escalating schema: 125 mg/m2 on day 4 and 250mg/m2 on day 6, with F (25 mg/m2/d) on days 6 to 8. In subsequent 28-day cycles (up to 6), the dose of G is escalated to 3 mg/kg/d days 1 to 7, with R 375 mg/m2 on day 5 and F days 5 to 7.Results: To date, 24 pts have been enrolled (19 PT and 5 UT). Characteristics included: median age, 56.5 yrs (range 25–82 yrs); Rai stage III, 6 pts (4 PT and 2 UT) and IV, 6 pts (6 PT and 0 UT). Median prior regimens (PT pts), 2; 13/19 (68%) had received F and R previously. Median # cycles administered: 6 (both UT and PT). Four PT pts discontinued treatment before completing 6 cycles, 2 due to disease progression, and 2 with prolonged (> 4 week) Grade 3 thrombocytopenia/neutropenia. One PT pt completed only 3 cycles of R due to an R-related infusion reaction, but completed 6 cycles of G and F. Among the 5 UT pts, there was 1 case of grade 4 neutropenia. Among the 19 PT pts, there were 2 cases each of grade 4 thrombocytopenia and neutropenia. One of 5 UT pts had an SAE of reversible acute renal insufficiency. Seven of 19 PT pts (8 events total) experienced an SAE. These included R-related infusion reactions (2 pts), bacteremia (2 pts) and 1 pt each with fever, lymph node abscess, pneumonia, and thrombocytopenia/neutropenia. Responses have been observed in 5/5 UT pts (1 molecular CR (mCR), 1 nPR and 3 PR) and 10/19 PT pts (1 mCR, 2 nPR and 7 PR).Conclusions: 24 pts have been treated with the combination of FRG. Employing a three-day regimen of F, good tolerability and efficacy have been noted in relapsed/refractory patients. Based on these results, an additional cohort receiving a full 5-day regimen of F is ongoing with measurement of Genasense PK and bcl-2 intracellular levels (mRNA and protein).

SPC2996 - A New Bcl-2 Inhibitor for the Treatment of CLL.

The proapoptotic oligonucleotide agent - SPC2996, has been developed by Santaris Pharma A/S, as a specific Bcl-2 mRNA antagonist. SPC2996 was selected from our inhouse discovery research in a library of short antisense oligonucleotides with Locked Nucleic Acid (LNA). LNA brings a significant increase in the affinity towards complementary RNA and in addition remarkably increases the bio-stability.Stability was evaluated in human and rodent plasma with SPC2996 capable of 20day half life in human serum. mRNA and protein analyses were used for showing specific downregulation of Bcl-2 in cancer cell lines and this reduction was associated with induction of apoptosis. Cellular Bcl-2 responses on mRNA and protein are seen from 1nM of SPC2996. These effects lead to apoptosis induction. Anti- tumor activity was studied in xenotransplanted athymic mice models of human cancer. SPC2996 was equally effective as Genasense in these models.That SPC2996 specifically dowregulates Bcl-2 was demonstrated in primate studies. Side by side comparison with Oblimersen sodium in these studies showed SPC2996 effectively downregulated Bcl-2 at 3mg/kg while Oblimersen sodium showed little or no target downregulation. Microarray analyses were used to demonstrate specificity of target downregulation.With SPC2996 we bring the first member of a new generation of safe, potent and specific mRNA antagonist drugs, exploiting the benefits of LNA. SPC2996 provides the cancer patient with the possibility of lower and less frequent dosing, which is unprecedented by any other oligonucleotide inhibitor of Bcl-2 used in clinical trials.

Phase I to II Multicenter Study of Oblimersen Sodium, a Bcl-2 Antisense Oligonucleotide, in Patients With Advanced Chronic Lymphocytic Leukemia

To determine the maximum-tolerated dose (MTD), efficacy, safety, and pharmacokinetics of oblimersen sodium in patients with advanced chronic lymphocytic leukemia (CLL). Eligible patients had relapsed or refractory CLL after treatment with fludarabine. Oblimersen was administered at doses ranging from 3 to 7 mg/kg/d as a 5-day continuous intravenous infusion in cycle 1 and as a 7-day continuous intravenous infusion in subsequent cycles every 3 weeks in stable or responding patients. Forty patients were enrolled and treated (14 patients in phase I and 26 patients in phase II). Dose-limiting reactions in phase I included hypotension and fever, and the MTD for phase II dosing was established at 3 mg/kg/d. Two (8%) of 26 assessable patients achieved a partial response. Other evidence of antitumor activity included > or = 50% reduction in splenomegaly (seven of 17 patients; 41%), complete disappearance of hepatomegaly (two of seven patients; 29%), > or = 50% reduction of lymphadenopathy (seven of 22 patients; 32%), and > or = 50% reduction in circulating lymphocyte counts (11 of 22 patients; 50%). Adverse events included transient hypotension, fever, fatigue, night sweats, diarrhea, nausea, vomiting, hypokalemia, and cough. Plasma concentrations of oblimersen (parent drug) and its major metabolites were variable. Renal clearance represented only a small portion of total parent drug clearance. Dosing with oblimersen sodium in patients with CLL is limited by development of a cytokine release syndrome that is characterized by fever, hypotension, and back pain. Oblimersen sodium has modest single-agent activity in heavily pretreated patients with advanced CLL, and further evaluation of its activity in combination with cytotoxic drugs is warranted.

Long-term survival results of a randomized multinational phase 3 trial of dacarbazine (DTIC) with or without Bcl-2 antisense (oblimersen sodium) in patients (pts) with advanced malignant melanoma (MM)

7506 Background: Chemotherapy resistance of MM has been linked to anti-apoptotic proteins, including Bcl-2 that is over-expressed in > 80% of pts. Oblimersen sodium (Genasense; G) targets bcl-2 mRNA and increases apoptosis when added to chemotherapy. We conducted a randomized trial of DTIC (D) alone compared with D plus G in pts with advanced MM. The results of this study, reported after all pts had been enrolled for a minimum of 6 mos, indicated a non-statistically significant difference (P=0.18) in overall survival (OS) for the intent-to-treat population (ITT). (Millward et al, JCO 2004; 22: 14S (abstract 7505)). However, there was a statistically significant difference in landmark analysis at 15 and 18 mos. We report here the update of OS 21 mos after completion of enrollment, as well as follow-up status of pts achieving a complete remission (CR) (11 on G/D vs 2 on D). Methods: 771 pts randomized to either G/D or D alone were followed every 2 mos for a total of 24 mos post-randomization. Data were coll...

Phase II study of oblimersen sodium and rituximab in patients with recurrent B-cell non-Hodgkin’s lymphoma

6611 Background: Oblimersen sodium (Genasense;GNS) is an 18-mer oligonucleotide that targets the mRNA of Bcl-2, a protein that inhibits apoptosis and confers treatment resistance. GNS has shown marked activity in xenograft models of non-Hodgkin’s lymphoma (NHL) and enhances the antitumor activity of rituximab (RIT). We are conducting a phase II study to determine the efficacy and toxicity of GNS + RIT in patients (pts) with recurrent B-cell NHL. Methods: GNS (3mg/kg/d) was administered as continuous IV infusion for seven days in weeks 1,3, and 5 (d1–7,15–21,29–35). RIT (375 mg/m2) was given weekly for 6 doses (d3,8,15,22,29,36). Patients whose disease did not progress were allowed to receive one additional cycle. Prior exposure to rituximab was permitted. Results: To date 29 have been enrolled. Thirteen pts had follicular lymphoma (FL), 5 large cell lymphoma (LCL), 5 small lymphocytic lymphoma (SLL), 3 mantle cell lymphoma (MCL), 2 mucosa-associated lymphoid tissue (MALT) lymphoma, and one B-cell lymphoma not further classified (NOS). Median number of prior treatments was 2 (range 1–3). Twenty-one pts are evaluable for response and toxicity. Eight pts (38%) responded to the combination therapy, 2 pts achieved a CR (1 MALT, 1 FL), 1 pt achieved an unconfirmed CR (FL), 5 pts achieved a PR (1 MCL, 2 FLCL, 1 SLL, 1FL). Two of the responses (1 CR,1 PR) were observed in rituximab-refractory pts. Common grade 3–4 toxicities included: reversible neutropenia in 7 pts (33%), thrombocytopenia in 2 pts (9%), non-neutropenic fever in 4 pts (19%). Conclusions: GNS can be safely combined with RIT and appears to be an active combination in recurrent B-cell lymphomas. Patients accrual is ongoing. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Genentech Genentech

Bcl-2 biomodulation with oblimersen sodium in combination with FOLFOX4 chemotherapy: A phase I study in metastatic colon carcinoma

3158 Background: Bcl-2 overexpression occurs in 30–94% of human colorectal cancer (CRC) specimens, appears to be an early event in CRC tumorigenesis & correlates with a negative prognosis in Dukes C disease. In addition, bcl-2 overexpression confers a multi-drug resistant phenotype to tumor cells, including resistance to platinum. Oblimersen is an antisense oligonucleotide directed to the bcl-2 mRNA, & has demonstrated bcl-2 protein inhibition in vitro & in vivo. The objectives of this phase I trial were to: 1) determine the maximum tolerated dose; 2) characterize the main toxicities; 3) assess plasma pharmacokinetics (PKs); 4) determine relevant predictive biomarkers, & 5) document antitumor activity in CRC patients treated with escalating doses of oblimersen, in combination with fixed doses of 5-FU, oxaliplatin and leucovorin (FOLFOX4 regimen). Methods: Oblimersen was given as a continuous IV infusion (CIV) on days 1–7 and 15–21, and the FOLFOX4 regimen was administered on days 6–7 and 20–21 of a 28-day cycle. The protocol was subsequently amended to shorten the duration of oblimersen CIV to 5 days (days 1–5 and 15–20), while maintaining the same duration of FOLFOX4. Results: A total of 16 patients [7 male/9 female), median age 52 (range 37–76)] have received 34 cycles of the combination over 3 dose levels of oblimersen: 5 mg/kg/day x 7 days, 7 mg/kg/day x 7days, and 7 mg/kg/day x 5 days. Prolonged neutropenia resulting in dose delay > 14 days in cycle 1 was dose limiting in four patients, one each at dose levels one & two, & two at dose level three, respectively. Additionally, one patient treated at dose level 2 experienced treatment-related grade 3 fatigue Other toxicities were mild to moderate (grade 1–2) & included vomiting (3 patients), diarrhea (5 patients), oral mucositis (4 patients) & proteinuria (5 patients). One patient experienced a complete response after cycle 2, & 2 patients had partial responses in 13 evaluable patients. Mean [±SD] Oxaliplatin AUC, t1/2, and Cl were 3.7 [1.4] μg/mL*h, 14.9 [4.4] h, 220 [102] mL/min/m2, respectively. Conclusions: Although active, enhanced hematologic toxicity made FOLFOX 4 in combination with oblimersen not feasible at 7 mg/kg/day x 5 days. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Genta, Sanofi Aventis, Genta

Targeting programmed cell death pathways with experimental therapeutics: opportunities in high-risk neuroblastoma

Neuroblastoma is a pediatric solid tumor with high morbidity and mortality in association with particular high-risk biological and clinical features (such as MYCN proto-oncogene amplification or advanced tumor stage). Such high-risk neuroblastomas may be initially responsive to cytoreductive therapies, yet the majority will ultimately demonstrate de novo or acquired chemoresistance leading to tumor progression and death. Insight into the genetic alterations responsible for these phenotypes are beginning to be gained, and subversion of inherent programmed cell death pathways is a common theme. Intact apoptosis pathways protect cells against neoplastic transformation and provide the mechanisms by which cytotoxic agents exert their effects. When these pathways are abolished through alterations in the cell death machinery, they complement deregulated oncogenes to promote tumor initiation and therapy resistance. Currently, therapeutic intensity for high-risk neuroblastoma has been advanced to near-tolerance with only modest gains in survival, and it is likely that further improvements in outcome will require innovative approaches that target key regulatory pathways that potentiate currently available therapies. Efforts to abrogate the cancer cell ‘survival bias’ engendered by alterations in death pathways are now a major focus in experimental cancer therapeutics, and their application to the problem of high-risk neuroblastoma form the basis of this review. These include agents that activate death receptors (TRAIL-agonists) or restore DISC competency (CDDO, DNA methyltransferase and HDAC inhibitors); reduce pro-survival Bcl2 homologues (Oblimersen sodium [AS-Bcl2], AS-Mcl1) or deliver a pro-apoptotic BH3 protein burden (BH3 peptides, gossypol, ABT737); or repress IAPs (Smac/Diablo peptides, AS-XIAP, AS-Survivin). As our knowledge of apoptosis dysregulation in neuroblastoma evolves, the possibilities for pro-apoptotic therapeutics seems not only promising, but a realistic adjunct to conventional treatments.

A Phase II, Pharmacokinetic, and Biological Correlative Study of Oblimersen Sodium and Docetaxel in Patients with Hormone-Refractory Prostate Cancer

To determine the antitumor activity and safety of oblimersen sodium, a phosphorothioate antisense oligonucleotide directed to the bcl-2 mRNA, with docetaxel in patients with hormone-refractory prostate cancer (HRPC) and to determine if relevant pharmacokinetic and pharmacodynamic variables of oblimersen or docetaxel influence response to this therapy. Patients with HRPC were treated with oblimersen sodium by continuous i.v. infusion on days 1 to 8 with docetaxel given i.v. over 1 hour on day 6 every 3 weeks. Plasma samples were analyzed to characterize the pharmacokinetic variables of both oblimersen and docetaxel, and paired collections of peripheral blood mononuclear cells were collected to determine Bcl-2 protein expression pretreatment and post-treatment. Twenty-eight patients received 173 courses of oblimersen (7 mg/kg/d continuous i.v. infusion on days 1-8) and docetaxel (75 mg/m(2) i.v. on day 6). Prostate-specific antigen responses were observed in 14 of 27 (52%) patients, whereas 4 of 12 (33%) patients with bidimensionally measurable disease had objective responses. The mean oblimersen steady-state concentration (C(ss)) was a significant determinant of antitumor activity; mean C(ss) values were higher in responders compared with nonresponders (6.24 +/- 1.68 versus 4.27 +/- 1.22; P = 0.008). The median survival of all patients was 19.8 months. Bcl-2 protein expression decreased a median of 49.9% in peripheral blood mononuclear cells post-treatment, but the individual incremental change did not correlate with either oblimersen C(ss) or response. Oblimersen combined with docetaxel is an active combination in HRPC patients demonstrating both an encouraging response rate and an overall median survival. The absence of severe toxicities at this recommended dose, evidence of Bcl-2 protein inhibition, and encouraging antitumor activity in HPRC patients warrant further clinical evaluation of this combination, including studies to optimize oblimersen C(ss).

Phase I Study of Oblimersen Sodium, an Antisense to Bcl-2, in Untreated Older Patients With Acute Myeloid Leukemia: Pharmacokinetics, Pharmacodynamics, and Clinical Activity

Pharmacologic downregulation of Bcl-2, an antiapoptotic protein overexpressed in cancer, might increase chemosensitivity in acute myeloid leukemia (AML). Herein, we investigated the feasibility of this approach in untreated elderly AML patients by administering oblimersen sodium (G3139), an 18-mer phosphorothioate antisense to Bcl-2, during induction and consolidation treatments. Untreated patients with primary or secondary AML (stratified to cohort 1 or 2, respectively) who were > or = 60 years received induction with G3139, cytarabine, and daunorubicin at one of two different dose levels (45 and 60 mg/m2) and, on achievement of complete remission (CR), consolidation with G3139 and high-dose cytarabine. An enzyme-linked immunosorbent assay (ELISA)-based assay was used to measure plasma and intracellular concentrations (IC) of G3139. Bcl-2 mRNA and protein levels were quantified by real-time reverse transcriptase polymerase chain reaction and ELISA, respectively, in bone marrow samples collected before induction treatment and after 72 hours of G3139 infusion, prior to initiation of chemotherapy. Of the 29 treated patients, 14 achieved CR. With a median follow-up of 12.6 months, seven patients had relapsed. Side effects of this combination were similar to those expected with chemotherapy alone and were not dose limiting at both dose levels. After 72-hour G3139 infusion, Bcl-2/ABL mRNA copies were decreased compared with baseline (P = .03) in CR patients and increased in nonresponders (NRs; P = .05). Changes in Bcl-2 protein showed a similar trend. Although plasma pharmacokinetics did not correlate with disease response, the median IC of the antisense was higher in the CR patients compared with NRs (17.0 v 4.4 pmol/mg protein, respectively; P = .05). G3139 can be administered safely in combination with intensive chemotherapy, and the degree of Bcl-2 downmodulation may correlate with response to therapy.

Early Results of a Phase I Trial of Oblimersen Sodium for Relapsed or Refractory Waldenström's Macroglobulinemia

Oblimersen sodium is an antisense oligonucleotide to the first 6 codons of the B-cell leukemia gene 2 (bcl-2) open reading frame. It prevents the expression of the bcl-2 gene product and leads to apoptosis in cells that express Bcl-2. bcl-2 is one of the major apoptosis regulatory gene families and is found in a variety of low-grade B-cell non-Hodgkin's lymphomas. The in vitro use of oblimersen in Waldenström's macroglobulinemia (WM) cell line results in enhanced toxicity when exposed to fludarabine, dexamethasone, or rituximab. Oblimersen should also enhance the cytotoxic effect of chemotherapy in WM. Presented herein are early data on the phase I portion of a phase I/II study of oblimersen in WM to identify the maximum tolerated dose and to evaluate response in patients with symptomatic WM.

An exploratory analysis of exposure-toxicity (E-T) relationships with oblimersen sodium; potential for patient management

Background Oblimersen sodium is a phosphorothioate antisense oligonucleotide in development for treatment of various cancers in combination with chemotherapy. Aims (1) to perform an exploratory analysis from pooled clinical data to examine oblimersen E-T relationships, (2) to evaluate effects of age and gender on oblimersen exposure. Methods Data analysis techniques were descriptive, including scatter and box plots for continuous and categorical variables, respectively. Linear and logistic regression methods were used to examine correlation of oblimersen exposure with safety indices. Results Data used in this analysis were from 60 subjects (26–76 years of age) from two Phase I/II studies in advanced malignant melanoma and chronic lymphocytic leukemia. Subjects received oblimersen doses ranging from 170–800 mg/day for 5–7 days. A total of 143 dose events were recorded (a dose event being defined as one cycle of oblimersen therapy), of which 60% was obtained from males and 40% from females. Exploratory trend analyses showed that occurrence/grade of fever and headache appeared correlated with oblimersen exposure; however, no statistical significance was observed (p-value > 0.2). Gender and age did not correlate with oblimersen exposure. Conclusions Results from this preliminary analysis of oblimersen E-T relationships provide a framework for formal examination of these relationships in future clinical trials to potentially define dose-adjustments for toxicity management. Clinical Pharmacology & Therapeutics (2005) 77, P87–P87; doi: 10.1016/j.clpt.2004.12.224

A Phase I Trial of Oblimersen Sodium (G3139) for Relapsed or Refractory Waldenstrom Macroglobulinemia.

IntroductionAntisense oligonucleotides are used to inhibit messenger RNA function and inhibit protein translation. Bcl-2 expression proteins have been implicated in mediating resistance to apoptotic cell death in Waldenstrom Macroglobulinemia (WM). Oblimersen sodium is a specific inhibitor of Bcl-2 expression and has shown activity in multiple myeloma and in Waldenstrom cell lines. The in vitro data led to the development of a phase I study for WM patients with relapsed or refractory disease.Materials and MethodsEligible patients had symptomatic WM who had failed prior cytotoxic chemotherapy. All patients had to have one of the following: a hemoglobin <11 g/dL, a platelet count <100,000/uL, bulky lymphadenopathy, or hyperviscosity syndrome. As a phase I study, the primary end point was toxicity assessment, but all patients were assessed for response, using monoclonal protein levels. Patients were enrolled and evaluated in cohorts of three. Drug was administered as a 24-hour continuous infusion for 7 days every 21 days, with intrapatient dose escalation each subsequent cycle beginning at 3 mg/kg/day up to a maximum of 7 mg/kg/day days 1–7 for a maximum of 8 cycles.ResultsTo date 9 patients have been accrued, six at dose level one and three patients at dose level two. Data is available for the first six entered. Five women and 1 man have been accrued with a median age of 74.5 years, ranging from 58 to 81. Four patients had relapsed from prior therapy, 2 were refractory. Three had a history of transfusions. The median number of prior regimens was 4 (range 2–7). One patient had a dose-limiting toxicity on the first cycle of therapy, which was grade 3 fatigue and anorexia, and the dose for this patient was reduced. Two patients had non-hematologic grade 3 toxicity, possibly related to therapy. Five out of six patients on dose level one had grade 3 or greater hematologic toxicity. These toxicities occurred after cycle 1 was completed, during the toxicity observation period and were not considered dose limiting toxicities influencing dose escalation. Three patients required dose reductions in subsequent cycles. To date one patient has had a partial response with her serum M spike falling from 3.6 to 1.1 g/dL. Her quantitative IgM fell from 6,000 mg/dL to 1,000 mg/dL(figure).ConclusionOblimersen was well tolerated at the first dose level in patients with WM. Hematologic toxicity is frequent in this cohort with heavily involved bone marrows when the dose was escalated during successive cycles. Dose reductions with subsequent cycles were frequently required. Evaluation of the maximum tolerated dose continues. Data on response for this dose level is promising, where efficacy will be fully evaluated in the phase II portion of this trial. [Display omitted]

A Pilot Study of Genasense® (Oblimersen Sodium, Bcl-2 Antisense Oligonucleotide), Fludarabine and Rituximab in Previously Treated and Untreated Subjects with Chronic Lymphocytic Leukemia.

Bcl-2 is an anti-apoptotic protein closely linked to chemotherapy resistance and inferior survival in patients (pts) with CLL. Genasense(GNS) enhances apoptosis induced by fludarabine (F), dexamethasone, and rituximab (R) in vitro, and has limited single-agent activity in heavily pre-treated CLL pts. Down-regulation of Bcl-2 may further sensitize CLL cells to apoptosis induced by F and R without exposing subjects to the toxicity of alkylating agents. CLL and NHL pts occasionally exhibit a “cytokine release syndrome” (spiking fever, back pain, and occasional hypotension) with GNS treatment. We hypothesized that a “step dosing” approach with GNS, similar to that sometimes used for R, could ameliorate these effects and allow safe and effective combination of this agent with F and R. We are currently evaluating this combination in pts with either previously untreated (UT) or relapsed, previously treated (PT) CLL who require systemic treatment. Eligibility includes: plts ≥ 50,000/mm3; serum Cr ≤ 1.5 mg/dL; adequate organ function; negative Coombs; no history of autoimmune hemolytic anemia. In cycle 1, GNS is given by continuous intravenous infusion at 1.5 mg/kg/d days 1 to 7. R is given on a dose-escalating schema (day 4, 125 mg/m2; day 6, 250 mg/m2). F (25 mg/m2/d) is given on days 6 to 8. In subsequent 28-day cycles (up to 6), the dose of GNS is escalated to 3 mg/kg/d days 1 to7 days, with R 375 mg/m2 on day 5 and F days 5 to7. To date, 20 pts have been enrolled (17 PT and 3 UT). Characteristics included: median age, 62 yrs (range 39 to 82 yrs); Rai stage III (2 pts) and IV (6 pts).Prior to administration of either F or R, single-agent GNS treatment at the initial reduced dose in Cycle 1 resulted in a median decrease in lymphocytes of 15% (among all patients regardless of decline in lymphocyte count) (Baseline: 48.3 cells x 103/ml; day 4: 40.1 cells x 103/ml). For the 13 pts who experienced a decline in lymphocyte count in cycle 1 prior to F and R, the median percentage change was 17%, with 4 pts having a > 25% decrease. Three PT pts discontinued from study treatment prior to completing 6 cycles, 2 due to disease progression, and 1 with Grade 3 thrombocytopenia that was unresolved after 4 weeks. Among the 20 pts treated to date (9 ongoing), the most common grade 3 or higher adverse events have been neutropenia, pyrexia and thrombocytopenia. Serious adverse events have been noted in only 6 of 20 pts (all PT pts) and have included 2 pts with fever (1 neutropenic), 2 R infusion reactions, 1 lymph node abscess and 1 tumor lysis syndrome (with sepsis).Conclusions: 20 pts have been treated with combination GNS, F and R. Single-agent activity with GNS has been observed at a reduced dose of 1.5 mg/kg/d in cycle 1. The “step dosing” approach appears to be a well-tolerated, alternative approach to the administration of GNS. Further details of safety and efficacy will be presented.

Intracellular Levels of Oblimersen Sodium and Target Downregulation Correlates to Clinical Activity of bcl-2 Antisense in Acute Myeoid Leukemia (AML).

Oblimersen sodium (Ob, Genasense™) is an 18 mer phosphorothioate antisense directed against bcl-2, an antiapoptotic protein that mediates chemoresistance in malignant cells. In order to assess whether detectable intracellular concentrations (ICs) of Ob are achievable in vivo, we have developed a sensitive and specific ELISA-based assay. This assay involves Ob hybridization to a 5′-end overhang of a 3′-biotinylated capture probe ligated to a digoxigenin (Dig)-labeled probe, and detection by an anti-Dig-alkaline phosphatase system. In K562 cell extract, the assay was linear within 50–2000 pM range with a limit of quantification (LOQ) of 50 pM (equivalent to 5.0 fmol/100 μL). The withtin-run coefficients of variation (CVs) in 4 spiked concentrations were between 3–7% in 6 replicates with accuracy values between 93–109%. The between-run CVs were between 6–12% and accuracy values between 97–102%. The specificity of the assay was demonstrated by low cross reactivity with mismatched oligonucleotides and putative 3′-end metabolites shortened by 1, 2 or 3 nucleotides. Validation of IC measurement was performed in vitro in K562 cells treated with fluorescent labeled Ob conjugated to oligofectamine. At Ob concentrations between 0.1 – 10 μM, Bcl-2 mRNA downregulation measured by real-time RT-PCR occurred efficiently. Nonlinear regression analysis of a dose-response curve showed that 50% Bcl-2 downregulation (IC50) occurred at approximately 0.29 μM, corresponding to an Ob IC concentration of 37 pmole/mg protein. Cellular uptake was confirmed by microscopy and flow cytometry. To validate these results in vivo, we measured Ob IC in bone marrow samples from untreated AML pts aged > 60 yrs enrolled on the phase I study OSU 0164. These pts were induced with Ob 7 mg/kg/d CIVI on days 1–10, cytarabine 100 mg/m2/d CIVI on days 4–10 and daunorubicin administered iv at two dose levels (45 mg/m2/d IV and 60 mg/m2/d) on days 4–6. Among 21 pts assessable for clinical response and Bcl-2 levels, at pretreatment, Bcl-2 copy numbers (normalized to ABL) were higher among 12 pts who achieved a CR (median 85,325; range 19,120–149,100) than among 9 non-responsive (NR) pts (32,100 bcl-2 /abl copies; range 1,488–163,500) (P=.04; Mann-Whitney test). Following 72 hr Ob infusion, a decrease (−38%) in median Bcl-2/ABL mRNA copies in CR patients and an increase (+115%) in Bcl-2/ABL copies in NR pts (P=.002; Mann-Whitney test) were observed by real time RT-PCR. A trend in higher median IC of Ob was observed in CR pts (17.0 pmole/mg protein; range 1.5–30.0) as compared to NR pts (4.4 pmole/mg protein; range 0.33–28.0) (P=.06; Mann-Whitney test). Six of 7 pts with IC above the median obtained a CR. No differences were observed in the Ob plasma PKs between the CR pts [median steady state concentration (Css) 2.8 μg/mL, area-under-the-curve (AUC) 772 μg*hr/mL and clearance (Cl) 9.6 L/hr) and the NR pts (median Css 3.4 μg/mL, AUC 752 μg*hr/mL, Cl 6.4 L/hr). Although the number of samples analyzed was small, our data suggest that, despite interpatient variability of both Bcl-2 mRNA expression and Ob uptake, this antisense can be successfully delivered to pts and result in clinically relevant target downregulation. A Cancer and Leukemia Group B phase III AML study to characterize prospectively the interplay of IC levels of the Ob and Bcl-2 downregulation is in progress.

Randomized Multicenter Phase 3 Trial of High-Dose Dexamethasone (dex) with or without Oblimersen Sodium (G3139; Bcl-2 antisense; Genasense) for Patients with Advanced Multiple Myeloma (MM).

Over-expression of Bcl-2 has been linked to acquired dex resistance in MM cells. Conversely, reduction of Bcl-2 using oblimersen has been shown to enhance dex-induced apoptosis in MM cell lines and in fresh MM cells in culture (Liu et al., Blood 101:4105, 2003). Preliminary non-randomized clinical studies have suggested that oblimersen may potentiate the activity of VAD and dex/thalidomide in patients (pts) with resistant MM. We have conducted a randomized, multinational, Phase 3 trial of pts with advanced MM using dex given with or without oblimersen. Eligibility requirements included: relapsed or refractory MM; measurable M-protein in serum or urine; ≤ 6 prior regimens; ECOG PS ≤ 3; serum Cr ≤ 1.5 mg/dL; ANC > 1,000/ml; plts ≥ 50,000/ml. Exclusions: previous allogeneic transplant; other significant medical disease. Pts were stratified according to number of prior treatments (1 or 2 vs. ≥ 3 regimens), prior autologous stem cell transplant (yes/no), and primary resistance to vs. relapse from primary treatment. All pts received dex 40 mg p.o. x 4 days during weeks 1, 2 and 3. Pts randomized to oblimersen received 7 mg/kg/d x 7 days by IV infusion, beginning 3 days before dex treatment during the 1st and 3rd weeks, and during all subsequent dex cycles. Beginning on week 5, additional 4-day dex cycles were repeated in stable or responding pts every 3 weeks, for a maximum of 12 months. All pts received prophylactic H-2 antagonists, TMP/SMZ, and a bisphosphonate. Response assessments were conducted prior to each treatment cycle. The primary endpoint of the study was to compare time-to-disease progression between the 2 treatment groups. Secondary endpoint comparisons included overall survival, event-free survival at 6 months, overall response rates, response duration, clinical benefit, and safety. A total of 224 pts were randomized into the study. All pts have completed > 12 mos follow-up, and final results of this trial will be presented.

Phase 2 Study of Oblimersen Sodium (G3139; Bcl-2 Antisense; Genasense®) Plus Gemtuzumab Ozogamcin (Mylotarg®) in Elderly Patients with Relapsed Acute Myeloid Leukemia (AML).

Patients with relapsed AML over the age of 60 have a poor prognosis. Gemtuzumab ozogamicin (GO) has been approved for older pts in first relapse, although many pts who attain complete remission (CR) do not fully recover normal platelet count (so-called CRp). In vitro studies have shown that oblimersen down-regulates Bcl-2 in AML cells and enhances apoptotic cell death induced by GO. We conducted a Phase 2 study to evaluate the safety and efficacy of GO combined with oblimersen for older pts with AML. Eligibility requirements included: age ≥ 60 yrs; AML in 1st relapse; ≥ 3 mos 1st CR duration; ≥ 25% CD33-positive AML cells. Pts received oblimersen at a dose of 7 mg/kg/d for 7 days by CIV beginning on days 1 and 15; GO was given at a dose of 9 mg/m2 IV over 2 hrs on days 4 and 18. A total of 48 pts were enrolled (ITT population), all of whom received at least 1 dose of oblimersen; 9 pts failed to receive the required 2 doses of GO (per-protocol population, n=39). The median age was 67 (range, 59 to 88 yrs). Duration of 1st CR: < 6 mos: 7 pts; (15%); 6 to 12 mos: 29 pts (60%); > 12 mos: 12 pts (25%). No. of prior regimens: 1 (17 pts, 35%); 2 or 3 (26 pts, 54%); ≥ 4 (5 pts, 10%). Among treated pts, 79% completed 21 days of protocol therapy. Overall, 12 pts achieved a major response, either CR (n=5) or CRp (n=7), for an ITT response rate of 25% and a per-protocol response rate of 31%. The median time to remission was 52 days. Ten of the 12 responders survived > 6 mos, whereas only 6 non-responders survived ≥ 6 mos. Serious adverse events for the oblimersen/GO combination were qualitatively similar to those reported for GO alone and included among other reactions: Grade 3-4 febrile neutropenia (42%) or thrombocytopenia 33%; nausea; fever; rigors, and dyspnea. Treatment-emergent adverse reactions led to discontinuation of protocol therapy in 10 pts (21%). The most common serious adverse event was febrile neutropenia (25%). One pt (2.1%) died during treatment (sepsis) and 16 pts (33%) died within 30 days of last study medication (infection, bleeding, respiratory failure, progressive AML, and other disease-related complications). No episodes of VOD were observed. Oblimersen can be safely combined with GO; however, pts enrolled in this study appear to have had more unfavorable characteristics at entry compared with prior studies using GO alone in pts with relapsed AML. Therefore, assessment of an incremental benefit from the addition of oblimersen will require a randomized trial.