Browne, Leslie J.

Abstract Eukaryotic translation initiation factor 5A (eIF5A) has been implicated in the regulation of cell proliferation, apoptosis, and inflammation, and is the only known protein to be modified by hypusination. Hypusinated eIF5A, the predominant form of eIF5A in cancer cells, is involved in cell survival and activation of inflammatory pathways. In contrast, accumulation of the unhypusinated form of eIF5A is associated with apoptosis and mutants of eIF5A that cannot be hypusinated (e.g. eIF5AK50R) are pro-apoptotic. SNS01-T was designed to treat B-cell cancers and consists of two active components: a plasmid DNA expressing the pro-apoptotic eIF5AK50R under the control of a B cell-specific promoter, and an siRNA against an untranslated region of native eIF5A mRNA. When these two components are combined with linear polyethyleneimine (PEI), the nucleic acids are condensed into nanoparticles for protection from degradation in the blood and enhanced cellular delivery. The mode of action of SNS01-T is siRNA-mediated inhibition of hypusinated eIF5A and simultaneous over-expression of pro-apoptotic eIF5AK50R to induce cell death. In vitro cell studies and in vivo xenograft studies have demonstrated the efficacy of this approach. The safety and tolerability of intravenous administration of SNS01-T is being investigated in a first-in-human Phase1b/2a study in patients with relapsed or refractory multiple myeloma (MM), mantle cell lymphoma (MCL) or diffuse large B cell lymphoma (DLBCL). Eligible patients are being enrolled sequentially into four cohorts at increasing doses. Each patient receives an intravenous infusion of SNS01-T twice weekly for 6 consecutive weeks. Eligible patients must have been diagnosed with MM according to IMWG criteria, or with MCL or DLBCL with histologic confirmation. Patients also must have measurable disease, have relapsed or refractory disease after two or more prior treatment regimens, have a life expectancy of at least 3 months, and not be eligible to receive any other standard therapy known to extend life expectancy. The primary objective is to evaluate the safety and tolerability of multiple escalating doses of SNS01-T. Secondary objectives include analysis of pharmacokinetics, immunogenicity, pro-inflammatory cytokines, and therapeutic efficacy. The required 3 patients per cohort have completed the dosing schedule in cohorts 1 and 2 from a total of 10 patients enrolled (9 patients with MM and 1 with DLBCL). Of the ten patients enrolled, four completed the full treatment period, two did not complete dosing but were evaluable for safety, and four (three in cohort 1 and one in cohort 2) discontinued treatment after fewer than 8 doses and were not evaluable. There were no drug-related serious adverse events or dose limiting toxicities in either cohort 1 or 2. In cohort 1 (0.0125 mg/kg SNS01-T), two of three evaluable patients did not progress on treatment and were considered stable at week 3 and week 6, the end of the dosing regimen. The third patient progressed after receiving 10 of the 12 doses and was evaluable for safety. In cohort 2 (0.05 mg/kg), 3 patients (2 with MM and 1 with DLBCL) were evaluable for safety. Stabilization of serum monoclonal protein levels was observed in one MM patient of cohort 2. Two patients (1 with MM and 1 with DLBCL) progressed after receiving 8 of the 12 doses and were evaluable for safety. Results from ongoing pharmacokinetic studies, immunogenicity studies, and quantification of pro-inflammatory cytokines will be discussed. The planned dose levels for the third and fourth groups are 0.2 and 0.375 mg/kg, respectively. The results to date of this first-in-human clinical trial indicate that SNS01-T can be administered safely and the MTD has not yet been reached (Clinical Trials.gov Identifier: NCT01435720). Disclosures: Barranco: Senesco Technologies: Consultancy. Usmani:Celgene, Onyx, Millenium: Consultancy, Research Funding, Speakers Bureau. van Rhee:Jansen&Jansen: Research Funding. Thompson:Senesco Technologies: Consultancy, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Taylor:Senesco Technologies: stock options Other. Dondero:Senesco Technologies: Employment. Browne:Senesco Technologies Inc.: Employment, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees. Siegel:Celgene, Millenium, Onyx (same for all): Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau.

Abstract Background Eukaryotic translation initiation factor 5A (eIF5A) has been implicated in the regulation of cell proliferation, apoptosis, and inflammation. SNS01-T is a novel therapeutic with a dual mechanism of eIF5A modulation: inducing cell death via siRNA-mediated inhibition of hypusinated eIF5A while simultaneously causing over-expression of pro-apoptotic eIF5AK50R via a DNA plasmid with a B-cell promoter to induce tumor cell death, using a PEI vector. SNS01-T significantly inhibits tumor growth and increases survival in mouse models of myeloma (MM), mantle cell and diffuse large B-cell lymphoma. Methods This is an open label, phase 1-2 dose escalation study in pts with refractory B-cell cancers, comprising 4 SNS01-T dose cohorts: 0.0125, 0.05, 0.2 and 0.375 mg/kg twice weekly IV for 6 weeks. Key inclusion criteria are: MM per IMWG criteria or lymphomas or plasma cell leukemia with histologic confirmation; measurable disease, relapsed or refractory after ≥2 prior regimens; not eligible for standard therapy known to extend life expectancy. Primary endpoints are safety and tolerability of SNS01-T. Secondary endpoints include pharmacokinetics, tumor response (M protein, % plasma cells, radiologic response) and time to relapse or progression. Efficacy assessments were performed at baseline and after 12 infusions in all pts (week 6); myeloma pts were also assessed at week 3. Results All cohorts will have completed enrollment in August 2014 and dosing in cohort 4 will be complete by September. A total of 21 pts have been treated, of whom 18 currently have data available. Demographics are provided in Table 1. Abstract 4464. Table 1:DemographicsSNS01-T DoseOverall(n=18)0.0125 mg/kg(n=6)0.05 mg/kg(n=4)0.2 mg/kg(n=4)0.375 mg/kg(n=4)Median age (range)63 (55-77)61.5 (57-66)63 (60-77)68 (66-74)58 (55-71)Male, n (%)12 (67)5 (83)03 (75)4 (100)Caucasian, n (%)17 (94)6 (100)3 (75)4 (100)4 (100)Median weight in kg (range)84 (53-117)81 (69-103)58 (53-87)86 (77-92)97 (81-117)Median performance status (range)1 (0-2)1 (0-1)1 (0-2)0 (0-2)1 (0-1)Cancer type, n (%) Multiple myeloma DLBCL15 (83) 3 (17)6 (100) 03 (75) 1 (25)2 (50) 2 (50)4 (100) 0Median prior therapies (range)5 (2-17)4.5 (3-12)6.5 (2-13)7.5 (2-17)7 (5-14) Treatment-emergent adverse events (TEAE) were reported for all pts. The most frequently reported System Organ Classes were General Disorders and Administration Site Conditions (72%) and Gastrointestinal Disorders (56%), with somewhat higher reporting frequency in dose cohorts 3 and 4. The most commonly reported AEs were fatigue (50%), nausea (33%), infusion-related reaction (33%), chills (28%), thrombocytopenia (22%) and pyrexia (17%). Thrombocytopenia, nausea, fatigue, infusion reaction appeared to show some degree of dose relationship. Grade ≥3 TEAEs occurred in 50% of pts with no obvious dose relationship. The only grade ≥3 TEAE reported in >1 pt was thrombocytopenia (17%). There have been no treatment-related deaths. There was 1 DLT at dose level 4 (0.375 mg/kg). Pt 51-001 did not receive premedication prior to the third infusion of SNS01-T and consequently experienced a grade 4 infusion reaction, from which all symptoms resolved within 24 hours. Study treatment was discontinued and the protocol was amended to require the following premedication at each SNS01-T infusion: a corticosteroid, antihistamine and acetaminophen are obligatory, plus an opioid as clinically indicated. Preliminary efficacy was explored. To date, 2 pts have shown stable disease of myeloma at week 3 with some decrease in serum and urine disease markers and one pt with DLBCL had a 15% decrease in small lymph node disease with approximately a 5 month duration. These patients were in cohorts 3 and 4. Conclusions SNS01-T administration was feasible in all 4 dose cohorts with prophylaxis for infusion reactions. Early signs of potential efficacy are encouraging. Expansion of efficacy testing to more patients and combination studies are planned. Disclosures Siegel: Senesco: PI Other. McDonald:Senesco: PI Other. Novitzky:Senesco: PI Other. Bensinger:Senesco: PI Other. Craig:Senesco: PI Other. van Rhee:Senesco: PI Other. Gutierrez:Senesco: PI Other. Libby:Senesco: PI Other. Thompson:Senesco: Consultancy, Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Bexon:Senesco: Consultancy. Barranco:Senesco: Consultancy. Taylor:Senesco: Research Funding. Dondero:Senesco: Employment. Browne:Senesco: Employment. Kurman:Senesco: Consultancy. Lust:Senesco: PI Other.

Abstract Introduction eIF5A is the only known protein to be modified by hypusination and is highly conserved across species. Hypusinated eIF5A, the predominant form in normal and cancer cells, is involved in cell survival and inflammatory pathway activation. siRNAs targeting eIF5A inhibit NF-kB activation and reduce pro-inflammatory cytokine production. Accumulation of the unhypusinated lysine form of eIF5A is associated with apoptosis. Mutants of eIF5A that cannot be hypusinated (e.g. eIF5AK50R) are pro-apoptotic in vitro and have anti-tumoral activity in vivo in multiple cancer types including melanoma and lung cancer. SNS01-T is a novel therapeutic with a dual mechanism of eIF5A modulation: inducing cell death via siRNA-mediated inhibition of hypusinated eIF5A while simultaneously causing over-expression of pro-apoptotic eIF5AK50R via a DNA plasmid with a B-cell promoter to induce tumor cell death. SNS01-T significantly inhibited tumor growth and increased survival in mouse models of myeloma (MM), mantle cell and diffuse large B-cell lymphoma. The phase 1-2 study of SNS01-T has completed 4 planned dosing cohorts 0.0125, 0.05, 0.2 and 0.375 mg/kg twice weekly IV for 6 weeks in pts with refractory B-cell cancers. Methods PK and PD secondary endpoints included characterization of PK by measuring pExp5A plasmid DNA and eIF5A siRNA in blood and bone marrow (BM), assessing potential immunogenicity of SNS01-T by measuring serum concentrations of antibodies against SNS01-T nanoparticles, and measuring serum concentrations of select proinflammatory cytokines by enzyme-linked immunosorbent assay in serum and plasma samples. Blood PK timepoints were 30 minutes before the first infusion and at 30 minutes, 2, 6, and 24 hours after the first infusions on Week 1, Week 3, and Week 6 and at the 4, 8, and 12 week visits after the last infusion; BM samples were collected 1 day after the final infusion. Serum and plasma PD sampling timepoints were 30 minutes before and at 2, 6, and 24 hours after the first infusion on Week 1, Week 3, and Week 6, and at 4 weeks after the final infusion. Cytokines assayed included TNF-α, IFN-α, IFN-ß, IFN-g, CXCL1, IL-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, and IL-12. Results Table 1 shows data available for interpretation as of August 2014. The remaining samples are under analysis and will be presented. Abstract 2121. Table 1:Data available for interpretation (number of patients)SNS01-T DoseOverall(n=18)0.0125 mg/kg(n=6)0.05 mg/kg(n=4)0.2 mg/kg(n=4)0.375 mg/kg(n=4)Blood PK DNA and RNA156441Bone marrow PK82321Serum antibodies to SNS01-T nanoparticles186444Serum and plasma cytokines156441 Plasmid and siRNA blood levels generally peaked 30 minutes post-dosing at weeks 1, 3 and 6 of dosing. Both plasmid and siRNA exhibited rapid clearance from the blood, with levels dropping to near pre-dosing levels within 24 hours of administration. pExp5A plasmid DNA was detectable in the bone marrow of 2 pts at cohort 1, 2 at cohort 2, 1 at cohort 3 and 1 at cohort 4. eIF5A siRNA was not detectable in bone marrow. No antibodies to SNS01-T nanoparticles were detected at any timepoint at any dose level. Cytokines remained within the expected range of inter-patient variability, similar to baseline across all timepoints at the first 2 dose levels. At dose level 3, levels of IL-6, IL-8 and TNF-α in particular increased at the 2 and 6 hour timepoints but had recovered to baseline levels 24-hours post dosing. This effect was more pronounced at the first infusion. Conclusions PCR analysis demonstrated the presence of both plasmid DNA and siRNA components of SNS01-T in blood at all dose levels, with a dose-dependent increase in plasmid copy number. Plasmid DNA was also detected in bone marrow collected 24 hours after the final infusion of SNS01-T. Pro-inflammatory cytokines did increase within hours of infusion but returned to baseline within 24 hours, synchronous with the clinical infusion reactions (see Abstract 70148). No evidence of an anti-SNS01-T antibody response was observed in any subject. Phase 2 trials are planned. Disclosures Bexon: Senesco: Consultancy. Craig:Senesco: PI Other. Siegel:Senesco: PI Other. Bensinger:Senesco: PI Other. Novitzky:Senesco: PI Other. McDonald:Senesco: PI Other. Gutierrez:Senesco: PI Other. Libby:Senesco: PI Other. van Rhee:Senesco: PI Other. Heidel:Senesco: Consultancy. Thompson:Senesco: Consultancy, Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Barranco:Senesco: Consultancy. Taylor:Senesco: Research Funding. Browne:Senesco: Employment. Kurman:Senesco: Consultancy. Lust:Senesco: PI Other. Dondero:Senesco: Employment.