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Patients with spinal muscular atrophy (SMA) have an autosomal recessive disease that limits their ability to produce survival motor neuron (SMN) protein in the CNS resulting in progressive wasting of voluntary muscles. Detailed studies over several years have demonstrated that phosphorothioate and 2'-O-methoxyethyl- modified antisense oligonucleotides (ASOs) targeting the ISS-N1 site increase SMN2 exon 7 inclusion, thus increasing levels of SMN protein in a dose- and time-dependent manner in liver, kidney and skeletal muscle, and CNS tissues only when administered intrathecally. On a dose basis, nusinersen was found to be the most potent ASO for SMN2 splicing correction in the CNS of adult mice. After nusinersen was found to increase levels of SMN protein in the CNS of mice and subhuman primates without causing significant adverse events, it was advanced into clinical studies in patients with SMA. These trials in SMA patients have demonstrated significant improvements in various measures of motor function and in progression to movement developments not normally seen in SMA patients. In addition, there have been significant extensions in life expectancy. These findings led to the U.S. and European approval of nusinersen for use in SMA patients of all ages., (Copyright 2017 Clarivate Analytics.)

A thorough analysis of clinical trial data in the Ionis integrated safety database (ISDB) was performed to determine if there is a class effect on platelet numbers and function in subjects treated with 2'-O-methoxyethyl (2'MOE)-modified antisense oligonucleotides (ASOs). The Ionis ISDB includes over 2,600 human subjects treated with 16 different 2'MOE ASOs in placebo-controlled and open-label clinical trials over a range of doses up to 624 mg/week and treatment durations as long as 4.6 years. This analysis showed that there is no class generic effect on platelet numbers and no incidence of confirmed platelet levels below 50 K/μL in subjects treated with 2'MOE ASOs. Only 7 of 2,638 (0.3%) subjects treated with a 2'MOE ASO experienced a confirmed postbaseline (BSLN) platelet count between 100 and 50 K/μL. Three of sixteen 2'MOE ASOs had >10% incidence of platelet decreases >30% from BSLN, suggesting that certain sequences may associate with clinically insignificant platelet declines. Further to these results, we found no evidence that 2'MOE ASOs alter platelet function, as measured by the lack of clinically relevant bleeding in the presence or absence of other drugs that alter platelet function and/or number and by the results from trials conducted with the factor XI (FXI) ASO.

The common chemical and biological properties of antisense oligonucleotides provide the opportunity to identify and characterize chemical class effects across species. The chemical class that has proven to be the most versatile and best characterized is the 2'-O-methoxyethyl chimeric antisense oligonucleotides. In this report we present an integrated safety assessment of data obtained from controlled dose-ranging studies in nonhuman primates (macaques) and healthy human volunteers for 12 unique 2'-O-methoxyethyl chimeric antisense oligonucleotides. Safety was assessed by the incidence of safety signals in standardized laboratory tests for kidney and liver function, hematology, and complement activation; as well as by the mean test results as a function of dose level over time. At high doses a number of toxicities were observed in nonhuman primates. However, no class safety effects were identified in healthy human volunteers from this integrated data analysis. Effects on complement in nonhuman primates were not observed in humans. Nonhuman primates predicted safe doses in humans, but over predicted risk of complement activation and effects on platelets. Although limited to a single chemical class, comparisons from this analysis are considered valid and accurate based on the carefully controlled setting for the specified study populations and within the total exposures studied.

Aims: Custirsen (OGX-011/TV-1011), a second-generation antisense oligonucleotide (ASO) that reduces clusterin production, is under investigation with chemotherapy in patients with solid tumours. Custirsen is associated with constitutional symptoms (CS) that may interfere with clinical pharmacology investigations, such as QT interval studies. Experience with other ASOs suggests NSAID premedication may ameliorate CS, but we observed suboptimal outcomes in healthy subjects given custirsen and NSAIDs. We sought to establish a custirsen regimen for future clinical pharmacology studies in healthy subjects., Methods: Subjects received custirsen (640 mg intravenously over 120 min) with dexamethasone premedication or increasing doses (320, 480, 640 mg over 6 days) of custirsen with dexamethasone premedication, then one full custirsen dose without premedication on day 8. Incidence/severity of adverse events (AEs) and extensive electrocardiogram readings were evaluated. Pharmacokinetic parameters were estimated., Results: AEs included CS, elevated transaminases and prolonged activated partial thromboplastin time (aPTT) that were predominantly grade 1/2. Administration of increasing custirsen doses and dexamethasone premedication reduced the incidence of CS associated with full dose custirsen. Transaminase elevation showed a dose-dependent effect (0% at days 2, 4, 27% at day 6) with the highest custirsen doses. Increasing doses of custirsen may have mitigated the severity but not incidence of aPTT prolongation. Neither regimen was associated with cardiac repolarization changes in QT values or concentration-effect analyses. The custirsen pharmacokinetic profile was consistent with previous experience., Conclusion: Escalation of custirsen dose combined with dexamethasone premedication reduced CS associated with full dose custirsen and should be considered in future clinical pharmacology studies of custirsen., (© 2015 The British Pharmacological Society.)

Clusterin is a stress-induced cytoprotective chaperone that confers broad-spectrum treatment resistance and is overexpressed across a number of cancers. custirsen (OGX-011) is a promising novel second-generation antisense inhibitor of clusterin in clinical development. This article describes the mechanism of action and safety profile of OGX-011 and details the Phase I and II results in human solid organ malignancies. Two Phase III registration trials are currently under recruitment evaluating OGX-011 in combination with chemotherapy in patients with metastatic castration-resistant prostate cancer. These studies not only have the potential to significantly alter the standard of care in prostate cancer, but would also endorse a new class of targets and targeted therapy approach for cancer.

Trabedersen (AP-12009), which is being developed by Antisense Pharma GmbH, is a synthetic antisense oligodeoxynucleotide designed to block the production of TGFbeta2, a secreted protein that can exert protumor effects. Trabedersen is indicated for the treatment of malignant brain tumors and other solid tumors overexpressing TGFbeta2, such as those of the skin, pancreas and colon. Preclinical studies demonstrated that trabedersen reduced the secretion of TGFbeta2 in cultured tumor cells and exhibited antitumor activity ex vivo. It was also demonstrated that chronic intracerebral or intravascular administration of trabedersen did not cause life-threatening side effects in animals. This observation was confirmed in early clinical trials in patients with advanced cancer. In a phase IIb trial, improved survival was observed in patients with brain tumors who were intratumorally administered trabedersen, compared with patients receiving standard chemotherapy. However, this observation requires validation by an ongoing large-scale, phase III, randomized, controlled trial. Meanwhile, continued research on trabedersen should help to determine the roles of TGFbeta2 in cancer and also further the development of antisense technology.

Purpose: This phase I trial assessed the safety and tolerability of G3139 when given in combination with carboplatin and paclitaxel chemotherapy. The effect of G3139 treatment on Bcl-2 expression in peripheral blood mononuclear cells (PBMC) and paired tumor biopsies was also determined., Experimental Design: Patients with advanced solid malignancies received various doses of G3139 (continuous i.v. infusion days 1-7), carboplatin (day 4), and paclitaxel (day 4), repeated in 3-week cycles, in a standard cohort-of-three dose-escalation schema. Changes in Bcl-2/Bax transcription/expression were assessed at baseline and day 4 (prechemotherapy) in both PBMCs and paired tumor biopsies. The pharmacokinetic interactions between G3139 and carboplatin/paclitaxel were measured., Results: Forty-two patients were evaluable for safety analysis. Primary toxicities were hematologic (myelosuppression and thrombocytopenia). Dose escalation was stopped with G3139 at 7 mg/kg/d, carboplatin at area under the curve of 6, and paclitaxel at 175 mg/m(2) due to significant neutropenia seen in cycle 1 and safety concerns in further escalating chemotherapy in this phase I population. With G3139 at 7 mg/kg/d, 13 patients underwent planned tumor biopsies, of which 12 matched pairs were obtained. Quantitative increases in intratumoral G3139 with decreases in intratumoral Bcl-2 gene expression were seen. This paralleled a decrease in Bcl-2 protein expression observed in PBMCs., Conclusions: Although the maximal tolerated dose was not reached, the observed toxicities were consistent with what one would expect from carboplatin and paclitaxel alone. In addition, we show that achievable intratumoral G3139 concentrations can result in Bcl-2 down-regulation in solid tumors and PBMCs.

Purpose: To determine the maximum-tolerated dose, toxicity, pharmacokinetics, and biologic effects of G3139 when administered with doxorubicin and cyclophosphamide to children with relapsed solid tumors., Patients and Methods: Patients received a 7-day continuous infusion of 3, 5, or 7 mg/kg/d of G3139 every 21 days. Doxorubicin, cyclophosphamide, and dexrazoxane were administered on days 5 and 6 of the infusion. Pharmacokinetics and biology studies were performed during the first course., Results: Thirty-seven patients, median age 14 years (range, 1 to 19 years), were enrolled, of whom 29 were fully assessable for toxicity. Because of dose-limiting neutropenia, doses of doxorubicin 30 mg/m2/d for 2 days, dexrazoxane 300 mg/m2/d for 2 days, and cyclophosphamide 500 mg/m2/d for 2 days were reduced initially, but with the addition of granulocyte colony-stimulating factor (GCSF), could be re-escalated to starting doses. At the 7 mg/kg/d dose level, only one of six patients experienced DLT (neutropenia > 7 days). At this dose, the average (+/- standard deviation) steady-state G3139 concentration was 2.04 +/- 1 microg/mL, a concentration associated with biologic activity. Eleven of 15 patients had reduced bcl-2 expression in peripheral-blood mononuclear cells at the first assessable time point of G3139 exposure, and in eight of 14 patients with serial specimens this reduction persisted through day 6., Conclusion: The recommended phase II dose of G3139 is 7 mg/kg/d as a 7-day continuous infusion, with cyclophosphamide 500 mg/m2/d and doxorubicin 30 mg/m2/d on days 5 and 6, followed by GCSF. G3139 may accentuate the myelosuppressive effects of doxorubicin and cyclophosphamide. Evidence for biologic effects of G3139 was demonstrated.

Oblimersen is an antisense oligonucleotide developed by Genta for systemic use as an injection. It comprises a phosphorothioate backbone linking 18 modified DNA bases. Oblimersen targets the first six codons of Bcl-2 mRNA to form a DNA/RNA complex. The duplex is subsequently recognised as a foreign message and is cleaved enzymatically, thereby destroying the Bcl-2 message. The Bcl-2 protein, which is a potent inhibitor of apoptosis, is overexpressed in many cancers, including follicular lymphomas, breast, colon and prostate cancers, and intermediate-/high-grade lymphomas. By reducing the amount of Bcl-2 protein in cancer cells, oblimersen may enhance the effectiveness of conventional anticancer treatments. Genta has reported results from randomised phase III trials of oblimersen in four different indications: malignant melanoma, chronic lymphocytic leukaemia (CLL), multiple myeloma and acute myleoid leukaemia (AML). A negative opinion has been issued for the company's MAA for the product in the treatment of malignant melanoma in the EU; the EMEA has indicated an additional confirmatory trial is needed in this indication for approval. An NDA for CLL was deemed non-approvable by the US FDA; the company is appealing this decision. The phase III trials in multiple myeloma and AML did not meet their primary endpoints. Phase I and II trials are also underway or have been completed for a range of other cancer types. Genta and sanofi-aventis (formerly Aventis) entered into a collaboration agreement in 2002; however, this agreement was terminated by sanofi-aventis in May 2005. Genta became solely responsible for all costs relating to oblimersen at this time. Genta expanded its Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute in November 2001. The expanded collaboration was to investigate the use of oblimersen in combination with standard anticancer therapy in a broad range of cancers. This expansion occurred following the Gensynergy project, which showed that oblimersen was synergistic with other anticancer therapies. Genta signed a 5-year manufacturing agreement with Avecia Ltd in December 2002 to supply it with oblimersen. Genta's NDA was submitted to the FDA in December 2005 and accepted for review in March 2006. The application was based on data from a phase I/II trial (NCT00021749) of oblimersen alone in approximately 40 patients and a phase III study (NCT00024440) of 241 patients who received fludarabine and cyclo-phosphamide with or without oblimersen. Genta received a Special Protocol Assessment (SPA) from the FDA in October 2006 for a randomised, pivotal, clinical trial of oblimersen in CLL. The trial will be conducted in patients who have not received prior chemotherapy and who would be randomised to receive fludarabine and rituximab with or without oblimersen. This trial has not yet begun.Fast-track status was given to oblimersen for CLL in June 2003 by the FDA. Oblimersen previously obtained orphan drug status in the US and EU for CLL in September 2001. Genta previously submitted the MAA under the centralised licensing procedure and Spain and France were assigned as rapporteur and co-rapporteur countries, respectively. It was supported by an extended 24-month follow-up of patients from a phase III study (NCT00016263) of oblimersen plus dacarbazine. The EMEA validated the MAA for review in January 2006. Genta received a number of scientific questions from the EMEA in June 2006, which the company responded to. Genta intends to file a formal complaint and a request for correction of information with the FDA under the Federal Data Quality Act. The complaint is related to a key statistical analysis of the company's data for oblimersen in the treatment of melanoma used by the FDA at the Oncology Drug Advisory Committee (ODAC) in May 2004. Genta believes that analysis sought to discredit the finding that treatment with oblimersen significantly increased progression-free survival; ODAC previously agreed this endpoint would support full approval in the absence of a survival improvement in patients with advanced melanoma.A rolling NDA submission was submitted to the FDA in the third quarter of 2003; however, Genta and Aventis withdrew the NDA after the application failed to gain marketing approval from the FDA's Oncology Drug Advisory Committee (ODAC). In May 2004, ODAC voted that phase III trial results did not provide substantial evidence of effectiveness to outweigh toxicity of oblimersen treatment in patients with metastatic melanoma. Genta has the option to resubmit this application. The FDA gave oblimersen orphan drug status for malignant melanoma in August 2000. In October 1999, fast-track status was given to oblimersen by the FDA for malignant melanoma when used in combination with dacarbazine. In addition, oblimersen received orphan drug status for malignant melanoma in Australia in October 2006.A phase III study (NCT00016263) of oblimersen in combination with dacarbazine was conducted in patients with malignant melanoma. The combination treatment did not significantly increase overall survival time, but did significantly increase progression-free survival time, compared with dacarbazine treatment alone. The phase III trial enrolled 771 patients at 140 sites in 12 different countries. Patients were randomly assigned to receive dacarbazine alone or in combination with oblimersen. The primary endpoint of this trial was to compare the overall survival between the two treatment arms. Secondary endpoints included comparative analyses of progression-free survival and tumour response. Genta will conduct another phase III study of oblimersen in patients with advanced melanoma. The trial is designed to provide additional safety and efficacy evidence of the drug, in combination with dacarbazine, in patients who have not previously received chemotherapy. Approximately 300 patients are expected to be enrolled in the trial, which is planned to begin during mid-2007, at sites throughout Europe, Australia, and North and South America. Genta is conducting a phase I clinical trial (NCT00409383) to evaluate the combination of oblimersen, ABI 007, and temozolomide in chemotherapy-naive patients with advanced melanoma. This trial was initiated in November 2006 and is the first follow-on study to Genta's phase III trial of oblimersen plus dacarbazine. Oblimersen received orphan drug status in the US and EU for multiple myeloma in September 2001. In addition, fast-track designation was given to oblimersen by the FDA in the same month.A phase I/II clinical study (NCT00062244) of oblimersen was conducted by the NCI in patients with Waldenstrom's macroglobulinaemia, a disease that is similar to multiple myeloma. The study results indicated that oblimersen may be a useful treatment in this group of patients (all had high levels of Bcl-2 expression). In June 2003, Genta and Aventis announced the presentation of clinical data from a phase II trial of oblimersen in combination with docetaxel injection concentrate for patients with advanced HRPC. Researchers reported that these findings validated progression into phase III trials. Genta has licensed eight US patents relating to oblimersen and its backbone chemistry and these expire between 2008 and 2015. Genta has two pending US patent applications that relate to oblimersen. Corresponding patent applications have been filed in Canada, Europe and Japan. Genta owns three US patents relating to methods of using oblimersen that will expire in 2020, and also has approximately 45 corresponding foreign patent applications.

Targeting unique mRNA molecules using antisense approaches, based on sequence specificity of double-stranded nucleic acid interactions should, in theory, allow for design of drugs with high specificity for intended targets. Antisense-induced degradation or inhibition of translation of a target mRNA is potentially capable of inhibiting the expression of any target protein. In fact, a large number of proteins of widely varied character have been successfully downregulated using an assortment of antisense-based approaches. The most prevalent approach has been to use antisense oligonucleotides (ASOs), which have progressed through the preclinical development stages including pharmacokinetics and toxicological studies. A small number of ASOs are currently in human clinical trials. These trials have highlighted several toxicities that are attributable to the chemical structure of the ASOs, and not to the particular ASO or target mRNA sequence. These include mild thrombocytopenia and hyperglycemia, activation of the complement and coagulation cascades, and hypotension. Dose-limiting toxicities have been related to hepatocellular degeneration leading to decreased levels of albumin and cholesterol. Despite these toxicities, which are generally mild and readily treatable with available standard medications, the clinical trials have clearly shown that ASOs can be safely administered to patients. Alternative chemistries of ASOs are also being pursued by many investigators to improve specificity and antisense efficacy and to reduce toxicity. In the design of ASOs for anticancer therapeutics in particular, the goal is often to enhance the cytotoxicity of traditional drugs toward cancer cells or to reduce the toxicity to normal cells to improve the therapeutic index of existing clinically relevant cancer chemotherapy drugs. We predict that use of antisense ASOs in combination with small molecule therapeutics against the target protein encoded by the antisense-targeted mRNA, or an alternate target in the same or a connected biological pathway, will likely be the most beneficial application of this emerging class of therapeutic agent.

Bcl-2 protein is upregulated in a wide variety of lymphoid malignancies, including chronic lymphocytic leukemia (CLL). The protein is thought to be responsible for maintaining the viability of malignant lymphoid cells and may contribute to chemotherapy and radiotherapy resistance. Previous studies have shown that reduction of bcl-2 expression by antisense therapy sensitizes cells to chemotherapy-induced apoptosis. In vitro, the Bcl-2 antisense drug oblimersen sodium (Genasense, previously known as G3139) enhances the apoptotic response in CLL cells to fludarabine (Fludara), corticosteroids, alemtuzumab (Campath), and rituximab (Rituxan). A phase I trial in patients with refractory/relapsed CLL showed that patients with CLL were more sensitive to oblimersen than patients with solid tumors. The maximum tolerated oblimersen dose was 3 mg/kg/d, and the most common dose-limiting reaction was hypotension, frequently in association with high spiking fever. In this study, oblimersen displayed limited single-agent activity, including tumor lysis syndrome, transient decreases in circulating CLL cells, and reduction of splenomegaly and size of lymph nodes. Major responses were observed in 9% of patients. Subsequently, a phase III trial evaluating fludarabine and cyclophosphamide with or without oblimersen (3 mg/kg/d for 7 days) was initiated in patients with relapsed or refractory CLL. This trial recently completed accrual of 241 patients.

Purpose: To assess the feasibility of administering oblimersen sodium, a phosphorothioate antisense oligonucleotide directed to the Bcl-2 mRNA, with docetaxel to patients with hormone-refractory prostate cancer; to characterize the pertinent pharmacokinetic parameters, Bcl-2 protein inhibition in peripheral blood mononuclear cell(s) (PBMC) and tumor; and to seek preliminary evidence of antitumor activity., Experimental Design: Patients were treated with increasing doses of oblimersen sodium administered by continuous i.v. infusion on days 1 to 6 and docetaxel administered i.v. over 1 h on day 6 every 3 weeks. Plasma was sampled to characterize the pharmacokinetic parameters of both oblimersen and docetaxel, and Bcl-2 protein expression was measured from paired collections of PBMCs pretreatment and post-treatment., Results: Twenty patients received 124 courses of the oblimersen and docetaxel combination at doses ranging from 5 to 7 mg/kg/day oblimersen and 60 to 100 mg/m(2) docetaxel. The rate of severe fatigue accompanied by severe neutropenia was unacceptably high at doses exceeding 7 mg/kg/day oblimersen and 75 mg/m(2) docetaxel. Nausea, vomiting, and fever were common, but rarely severe. Oblimersen mean steady-state concentrations were 3.44 +/- 1.31 and 5.32 +/- 2.34 at the 5- and 7-mg/kg dose levels, respectively. Prostate-specific antigen responses were observed in 7 of 12 taxane-naïve patients, but in taxane-refractory patients no responses were observed. Preliminary evaluation of Bcl-2 expression in diagnostic tumor specimens was not predictive of response to this therapy., Conclusions: The recommended Phase II doses for oblimersen and docetaxel on this schedule are 7 mg/kg/day continuous i.v. infusion days 1 to 6, and 75 mg/m(2) i.v. day 6, respectively, once every 3 weeks. The absence of severe toxicities at this recommended dose, evidence of Bcl-2 protein inhibition in PBMC and tumor tissue, and encouraging antitumor activity in HPRC patients warrant further clinical evaluation of this combination.

Background: It has been postulated that protein kinase C alpha (PKC-alpha) plays a pivotal role in signal transduction in tumor cancer cells. Aprinocarsen, a 20-base antisense oligonucleotide, has shown ability to inhibit PKC-alpha protein expression and inhibit tumor growth in human xenograft models. In a previous Phase I trial, the authors demonstrated the safety and some evidence of activity in ovarian carcinoma of aprinocarsen administered as a 21-day, continuous, intravenous infusion., Methods: In this Phase II trial, 36 patients with advanced ovarian carcinoma were treated with aprinocarsen at a dose of 2 mg/kg per day delivered as a 21-day, continuous, intravenous infusion. The primary objective was to determine the antitumor response, and the secondary objectives were to evaluate toxicity and to evaluate effects on quality of life (QOL)., Results: Between September 1997 and December 1999, 36 patients (median age, 58 years) were enrolled in this trial. Patients were stratified into 2 groups: a platinum-sensitive group (n = 12 patients) and a platinum-resistant group (n = 24 patients). All 36 patients were evaluable for toxicity, and 27 patients were fully assessable for antitumor response after 2 cycles of therapy. All patients had received prior treatments. No objective responses were noted in the platinum-sensitive group. In the platinum-resistant group, 1 patient had some evidence of antitumor activity indicated by a decrease in serum CA 125 and stable disease on imaging studies for 8 months. No changes were noted in overall patient ratings for any of the five QOL domains., Conclusions: When it was administered as a single agent, aprinocarsen did not have significant clinical activity in patients with advanced ovarian carcinoma. Further study may be warranted in combination with platinum-based regimens., (Copyright 2003 American Cancer Society.)

The regulation of apoptosis is an important potential target for anticancer therapy. The mitochondrial Bcl-2 protein inhibits apoptosis and is therefore an important mediator of resistance to treatment with traditional cytotoxic chemotherapy, radiotherapy and monoclonal antibody therapy. Oblimersen (Genasense, Aventis Pharmaceuticals / Genta Inc) is a 18mer antisense-oligonucleotide (ASO), which specifically binds to the first 6 codons of the human bcl-2 mRNA, resulting in degradation and destruction of the mRNA by RNAse H. Subsequently there is a significant decrease of bcl-2 translation. A growing number of preclinical and clinical studies suggests that the combination of cytotoxic therapy with Oblimersen results in synergistic anticancer efficacy in many hematologic and solid tumors. Due to its low toxicity profile, oblimersen is an ideal combination partner with conventional chemotherapy. Three randomized phase-III trials (malignant melanoma, chronic lymphocytic leukemia, multiple myeloma) have recently finished recruitment. The results of these studies will be available by the end of 2003. Based on preclinical data, a lot of nonrandomized phase-II studies on several different tumor types like AML, CML, NHL, prostate cancer and breast cancer are underway. The manipulation of proapoptotic and antiapoptotic factors in favor of proapoptotic factors by inhibition of the bcl-2 protein translation in order to enhance the efficacy of anticancer treatments represents a promising new treatment concept in oncology., (Copyright 2003 S. Karger GmbH, Freiburg)

Background: Hypermethylation and inactivation of tumor suppressor genes by the enzyme DNA methyltransferase may lead to neoplastic transformation. MG98, a phosphorothioate antisense oligodeoxynucleotide that is a specific inhibitor of mRNA for human DNA methyltransferase 1 (DNMT1), was evaluated in a phase I study., Patients and Methods: MG98 was given as a 2 h i.v. infusion twice weekly three weeks out of every four to patients with solid tumors. Pharmacokinetic evaluation was performed on days 1 and 15 of cycle 1 and mRNA expression of DNMT1 was measured in peripheral blood mononuclear cells (PBMCs)., Results: Nineteen patients were entered onto the study. A total of 74 cycles (range 1-18 cycles) were administered at dose levels from 40 to 480 mg/m(2). Dose limiting toxicity was seen in two of three patients at 480 mg/m(2) and consisted of a constellation of fever, chills, fatigue and, in one case, confusion beginning within 6 h after the first infusion. Other toxic effects included fatigue, anorexia, nausea, vomiting and diarrhea, reversible elevations in transaminases and partial thromboplastin time. Pharmacokinetic evaluation showed C(max) and AUC to be dose proportional with low inter- and intra-patient variability. No consistent changes in DNMT1 mRNA expression were noted in PBMCs. One partial response was documented in a patient with renal cell carcinoma treated at 80 mg/m(2)., Conclusions: The recommended dose of MG98 was 360 mg/m(2) given by 2 h infusion twice a week for three weeks out of every four. Phase II trials using this dose and schedule are underway.

Purpose: To evaluate the safety and pharmacokinetics of BCL-2 antisense oligonucleotide (G3139) administered by prolonged i.v. infusion in patients with advanced cancer., Experimental Design: A total of 35 patients was treated in cohorts of 3-6 with 0.6-6.9 mg/kg/day of BCL-2 antisense oligonucleotide as a continuous infusion for 14 or 21 days. Plasma levels of intact antisense oligonucleotide were measured in all patients., Results: G3139 was generally well tolerated. At the highest dose level examined in this study (6.9 mg/kg/day), fatigue and transient reversible elevations of serum transaminases (grades 2-3) became apparent after >or=7 days of treatment. Both reactions were believed to be drug related. Pharmacokinetic analyses showed that steady-state plasma concentrations of G3139 were reached approximately 10 h after starting the infusion and increased linearly across the range of doses administered

Antisense oligonucleotides offer the promise of therapeutic effect with few toxic effects, by virtue of their high selectivity. Preclinical studies have provided evidence of antisense effects in vitro and in vivo, and phase I clinical trials have demonstrated safety, feasibility and activity of antisense oligonucleotides for the treatment of cancer. This review summarizes the status of development of three anticancer antisense oligonucleotides from ISIS Pharmaceuticals.

Mixed-backbone oligonucleotides containing alternative phosphorothioate and phosphodiester linkages in the 2'-O-methylribonucleosides segment show increased affinity with complementary targets, increased stability towards nucleases in vitro and in vivo, and reduced phosphorothioate-related prolongation of partial thromboplastin time compared to phosphorothioate oligodeoxynucleotides, thereby providing antisense agents with reduced side effects.

There is increasing evidence that phosphorothioate oligonucleotides infused into the brain can cause a host of undesired side effects which compromise the antisense experiment. In studies on the corticotropin releasing factor type-2 receptor, several phosphorothioate oligonucleotides administered intraventricularly produced significant weight loss in rats. Four different phosphodiester and phosphorothioate oligonucleotide analogs were examined to identify molecules which could eliminate these side effects while maintaining good potency for antisense inhibition. Of these, chimeric oligonucleotides consisting of a mixed phosphodiester-phosphorothioate backbone, and having 2'-methoxyribonucleotide modifications in 60% of the oligonucleotide were the most optimal. Rats treated with these chimeric oligonucleotides gained weight at rates identical to that of saline-treated controls. In addition, the antisense oligonucleotide but not the mismatch control sequence reduced corticotropin releasing factor type-2 receptor binding of 125iodo-sauvagine in the lateral septum by 40-60% after 5 daily injections. Increasing the dosing period to 9 days reduced receptor binding by 78%. Reductions in protein binding were accompanied by comparable reductions in the in situ hybridization signal of the corticotropin releasing factor type-2 receptor mRNA. However, when an oligonucleotide analog incapable of supporting ribonuclease H activity was used, neither protein nor RNA binding levels were changed compared to saline-treated controls. These results suggest that ribonuclease H or enzymes with similar activity are critical to the antisense inhibition observed in the lateral septum., (Copyright 1998 Elsevier Science B.V.)

Background & Aims: Intercellular adhesion molecule 1 (ICAM-1) plays an important role in the trafficking and activation of leukocytes and is up-regulated in inflamed mucosa in Crohn's disease. ISIS 2302 is an antisense phosphorothioate oligodeoxynucleotide that inhibits ICAM-1 expression. The aim of this study was to obtain preliminary assessment of tolerability, pharmacology, and efficacy of ISIS 2302 in Crohn's disease., Methods: Twenty patients with active, steroid-treated Crohn's disease were randomized (3:1, ISIS 2302 to placebo) to receive over 26 days 13 intravenous infusions of ISIS 2302 (0.5, 1, or 2 mg/kg) or saline placebo in a double-blinded study. The patients were followed up for 6 months., Results: At the end of treatment. 47% (7 of 15) of ISIS 2302-treated and 20% (1 of 5) of the placebo-treated patients were in remission (Crohn's Disease Activity Index [CDAI] < 150). At the end of month 6, 5 of these 7 ISIS 2302-treated remitters were still in remission, and a 6th patient had a CDAI of 156. Corticosteroid usage was significantly lower (P = 0.0001) in the ISIS 2302-treated patients. These findings were corroborated by significant increases in beta7 and alpha d bearing CD3+ peripheral blood lymphocytes and by decreases in intestinal mucosal ICAM-1 expression during the treatment period., Conclusions: ISIS 2302 seems to be a well-tolerated and promising therapy for steroid-treated Crohn's disease.

Healthy male volunteers received single or multiple intravenous infusions of an intercellular adhesion molecule-1 antisense phosphorothioate oligodeoxynucleotide, ISIS 2302, in a rising-dose (0.06-2.00 mg/kg infused over 2 hr), double-blind, placebo-controlled trial. Brief, dose-related increases in activated partial thromboplastin time were seen at the time of peak plasma concentration (C(max)). Clinically insignificant increases in C3a were seen after higher, repeated doses, but C5a, blood pressure and pulse were unaffected. No adverse events or other laboratory abnormalities were related to treatment with the drug. ISIS 2302 C(max) was linearly related to dose and occurred at the end of infusion. Plasma half-life for intact drug (53-54 min) and total oligonucleotide (67-74 min) were similar at the two doses (0.5 and 2.0 mg/kg) at which extensive pharmacokinetic data were collected. Nonlinear changes in area under the plasma concentration/time curve and steady-state volume of distribution with increasing dose suggested a saturable component to disposition. Metabolites co-migrating with n-1, n-2 and n-3 chain-shortened versions of ISIS 2302 appeared very rapidly in plasma, and disposition and metabolism appeared unaltered by repeated dosing. ISIS 2302 was well tolerated and behaved reproducibly with respect to plasma pharmacokinetics and expected side effects.

Purpose: The phosphoprotein p53 is involved in transcriptional regulation and is detected in hematologic malignancies. In vitro incubation of acute myelogenous leukemia with OL(1)p53, a 20-mer phosphorothioate oligonucleotide complementary to p53 mRNA, results in leukemic cell death. A phase I dose-escalating trial was conducted to determine the toxicity of OL(1)p53 following systemic administration to patients with hematologic malignancies., Patients and Methods: Sixteen patients with either refractory acute myelogenous leukemia (n = 6) or advanced myelodysplastic syndrome (n = 10) participated in the trial. Patients were given OL(1)p53 at doses of 0.05 to 0.25 mg/kg/h for 10 days by continuous intravenous infusion., Results: No specific toxicity was directly related to the administration of OL(1)p53. One patient developed transient nonoliguric renal failure. One patient died of anthracycline-induced cardiac failure. Approximately 36% of the administered dose of OL(1)p53 was recovered intact in the urine. Plasma concentrations and area under the plasma concentration curves were linearly correlated with dose. Leukemic cell growth in vitro was inhibited as compared with pretreatment samples. There were no clinical complete responses., Conclusion: A phosphorothioate oligonucleotide, OL(1)p53, can be administered systemically without complications. This type of modified oligonucleotide can be administered without complete degradation, as it was recovered from the urine intact. This oligonucleotide may be useful in combination with currently available chemotherapy agents for the treatment of malignancies.

Human pharmacokinetics of an antisense oligodeoxynucleotide phosphorothioate (GEM 91) developed as an anti-human immunodeficiency virus (HIV) agent was carried out in this study. 35S-Labeled GEM 91 was administered to six HIV-infected individuals by means of 2-hour intravenous infusions at a dose of 0.1 mg/kg. Plasma disappearance curves for GEM 91-derived radioactivity could be described by the sum of two exponentials, with half-life values of 0.18 +/- 0.04 and 26.71 +/- 1.67 hours. The radioactivity in plasma was further evaluated by polyacrylamide gel electrophoresis, showing the presence of both intact GEM 91 and lower molecular weight metabolites. Urinary excretion represented the major pathway of elimination, with 49.15% +/- 6.80% of the administered dose excreted within 24 hours and 70.37% +/- 6.72% over 96 hours after dosing. The radioactivity in urine was associated with lower molecular weight metabolites. No drug-related toxicity was observed.

A synthetic phosphorothioate oligonucleotide was administered systemically to five patients with either relapsed or refractory acute myelogenous leukemia (AML), or myelodysplastic syndrome (MDS). Patients received a 10-day continuous intravenous infusion of this compound, which is complementary to p53 mRNA. No major toxicity attributable to a dose of 0.05 mg/kg/hr was observed. A range of approximately 9 to 18% of the administered dose was recovered in the urine as intact oligonucleotide. Evaluation of malignant cells recovered from bone marrow and peripheral blood at intervals before, during, and after treatment reveals no enhanced growth potential following oligonucleotide administration. Hence, a phosphorothioate oligonucleotide complementary to p53 mRNA can be administered at this dose level to humans without major toxicity. Higher doses need to be evaluated for toxicity and potential clinical efficacy.