ALBERT

Description: XmAb2513 is a novel humanized monoclonal antibody (mAb) that binds to the human cell surface antigen CD30 and demonstrates anti-proliferative activity against CD30-positive (CD30+) cell lines. XmAb2513 also has an engineered Fc region to enhance cell killing activity via recruitment of effector cells through increased binding affinity to Fcγ receptors (FcγRs). Consequently, XmAb2513 exhibits superior antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cell-mediated phagocytosis (ADCP), when compared to a native IgG1 (unengineered) version of the antibody. To evaluate the potential clinical activity of XmAb2513 in CD30+ diseases such as Hodgkin Lymphoma (HL) and Anaplastic Large Cell Lymphoma (ALCL), XmAb2513 was tested in murine subcutaneous xenograft models of HL using the CD30+ L540 cell line. In the ICR-SCID mouse strain, intraperitoneal (ip) administration of XmAb2513 at 3 mg/kg every 4 days for 10 doses (q4d ×10), gave a statistically significant reduction in tumor growth and enhanced survival relative to the control. At doses of 10 and 30 mg/kg XmAb2513 (ip, q4d ×10) tumor growth was not only slowed, but elimination of established tumors was observed in 3/9 and 5/9 animals respectively. The treatment was well-tolerated. Preclinical studies were conducted to evaluate the safety and pharmacokinetics of XmAb2513 in large animals. In vitro studies demonstrated that the cynomolgus monkey was the appropriate species for study. Binding affinities of XmAb2513 to both human and cynomolgus monkey CD30 and FcγRs were evaluated by Biacore methods and were found to be similar. Additionally, fluorescein-XmAb2513 gave similar staining patterns in immunohistochemistry cross-reactivity studies with normal human and cynomolgus monkey tissue panels. As evidenced by in-life observations single (0, 1 and 100 mg/kg XmAb2513, intravenous [iv] infusion) and repeat dose (0, 10, 30 and 100 mg/kg XmAb2513, q5d ×6, iv infusion) treatment with XmAb2513 was well-tolerated. Serum cytokines showed no trend that was indicative of an XmAb2513-related effect following single dose administration. The pharmacokinetics of XmAb2513 was also determined after either single or repeat dose administration. In the repeat dose study (0, 3, 10 and 30 mg/kg XmAb2513, q5d ×6, iv infusion) exposure increased in a dose proportional manner, and terminal half-life (t1/2) ranged from 12–17 days. In the single dose study (0, 1 and 100 mg/kg XmAb2513, iv infusion) exposure was also proportional to dose. The exposure and t1/2 data support an every other week dosing interval in the clinic. These preclinical data provide a rationale for the clinical testing of XmAb2513 in patients with hematologic malignancies that express CD30, specifically HL and ALCL, and support the safety of repeat administration of XmAb2513 in humans.

Description: CD19, a B cell–restricted receptor critical for B-cell development, is expressed in most B-cell malignancies. The Fc-engineered anti-CD19 antibody, XmAb5574, has enhanced Fcγ receptor (FcγR) binding affinity, leading to improved FcγR-dependent effector cell functions and antitumor activity in murine xenografts compared with the non–Fc-engineered anti-CD19 IgG1 analog. Here, we use XmAb5574 and anti-CD19 IgG1 to further dissect effector cell functions in an immune system closely homologous to that of humans, the cynomolgus monkey. XmAb5574 infusion caused an immediate and dose-related B-cell depletion in the blood (to

Description: Multiple treatment modalities are available for MF, but most result in inevitable relapse. Therefore, new treatment strategies that improve response rate and prolong response duration are greatly needed. TSEBT is a highly effective therapy in MF. LD-TSEBT (12 Gy) is much more tolerable than the conventional 36+ Gy dose, thereby allowing for re-treatment; however, LD-TSEBT has a less favorable complete response rate and response duration. Combining LD-TSEBT with immunostimulatory modalities in MF has a strong biological rationale, since radiation-induced exposure of cancer-specific antigens should be synergistic with concomitant stimulation of anti-cancer immune responses. Interleukin-12 is a robust candidate for radioimmunotherapy, as IL-12 has significant anti-MF activity as monotherapy, is very well tolerated without overlapping toxicity with TSEBT, and is a potent stimulator of innate and adaptive immunity. We report on a single-arm open-label phase 2a trial of combination of LD-TSEBT and NM-IL-12. Ten patients are planned for enrollment. Eligibility includes MF-type CTCL stages IB-IIIB and patients must be eligible for LD-TSEBT. TSEBT is started on study day 1 (fractionated 4 Gy/week, up to 12 Gy). NM-IL-12 is administered subcutaneously at 150 ng/kg on days 2 and 15, followed by 6 maintenance doses q4w at 100 ng/kg. The primary endpoint is safety with secondary endpoints being response rate and PFS. Currently, 6 patients are enrolled, 5 evaluable for response; 4 male; median age 55; three have stage IB, one IIB and one IIIB. Median number of previous therapies is 2 (0-6). The treatment was well-tolerated with only grade 1 or 2 AEs; most common AEs include grade 1 headache and chills. One patient achieved CR, 2 PR, and 2 SD. Median follow-up is so far 15 weeks and 5 patients remain on study. One patient has been withdrawn from the study due to development of a suspected PLC (pityriasis lichenoides chronica)-like skin reaction requiring topical steroid therapy. PK and PD analysis was completed in the first 4 patients. It demonstrated measurable drug levels in all patients studied, Cmax being 10.8-56.1 pg/ml achieved at 5-24 hours post injection. Interferon-γ and IP-10 (hallmark PD markers of IL-12 activity) were measurable after the first and the second injections in all patients. Levels of the inhibitory cytokine IL-10 were generally measurable after NM-IL-12 injections, but were very low (

Description: Interleukin-12 (IL-12) has potent immunoregulatory and hematopoietic properties, and exerts significant biological effects on natural killer (NK) cells, inducing IFNγ production and enhancing cytotoxicity. Two distinct NK cell populations correlate with their immunoregulatory functions. Mature CD56dimCD16bright NK cells represent 90% of the NK cells resident in the blood and can exert cytotoxic effects on transformed cells. Cytokine producing immature CD56brightCD16+/- NK cells exist in the blood (10% of total circulating NK cells) but are most prominently located in secondary lymphoid tissues. In the continued clinical development of recombinant human IL-12 (HemaMax™, rHuIL-12), to be used in combination with radiotherapy or chemotherapy for the treatment of cancer patients, we have performed a clinical safety study in healthy human subjects. A single subcutaneous (sc) dose of rHuIL-12 (12μg) was administered to 17 healthy human subjects. Placebo was administered to 5 healthy subjects. Peripheral blood samples were collected before rHuIL-12 administration, and up to Day 14 post administration. Immunophenotyping of blood cell populations was conducted by FACS. rHuIL-12 caused a transient decrease in peripheral blood CD56dimCD16bright NK cells, with a nadir (60% reduction from baseline) reached on Day 2 following rHuIL-12 administration. CD56dimCD16bright NK cell levels returned almost to baseline levels on Day 5. Placebo was without effect. Conversely rHuIL-12 caused an elevation in peripheral blood CD56brightCD16+/- NK cells, particularly between Days 2 and 3 after rHuIL-12 administration, which was sustained until a peak was reached on Day 5 (265% above baseline). Levels returned to baseline by Day 11, while placebo was without effect. rHuIL-12 did not impact the less functional CD56-CD16bright NK cell subset. CD56dimCD16bright NK cells expressing the IL-12 receptor β2 subunit (IL-12Rβ2+) showed a substantial, and transient, decrease in levels on Day 2. The plasma concentration of IFNγ was elevated to a peak over 35 fold above baseline level at 10hr. after rHuIL-12 administration. Human NK cells were negatively selected from highly enriched leukapheresis-derived blood and stimulated in vitro with 10 pM rHuIL-12. After 16hr. incubation these predominantly CD56dimCD16brightNK cells showed enhanced release of IFNγ and the increased killing of K562 cells, a human erythroleukemic cell line, when compared with vehicle controls. qPCR analysis of the human NK cell lysates showed rHuIL-12-induced elevation of CD56 (302%) and IL-12Rβ2 (587%) mRNA, when compared with vehicle controls. rHuIL-12 did not influence CD16 mRNA expression, but did increase the level of CD62L (L selectin, 206%) mRNA. The rapid 60% fall in circulating mature CD56dimCD16bright NK cells after rHuIL-12 administration to healthy human subjects suggests their immediate exit from peripheral blood into the tissue compartments. This could be mediated by the observed increase in NK cell CD62L mRNA expression seen in vitro. The sustained increase in immature CD56brightCD16+/- NK cell levels between Day 3 and 6 suggests their IL-12-induced development from CD34+ hematopoietic progenitor cells. In summary rHuIL-12 administration to healthy human subjects demonstrates differential effects on the two key NK cell populations in peripheral blood, increasing CD56brightCD16+/- NK cell numbers, potentially stimulating IFNγ release from and enhancing the cytotoxicity of the CD56dimCD16bright NK cells, and preparing this population for migration into tissues. rHuIL-12 thus shows excellent potential as an immunotherapeutic and hematopoietic agent for the treatment of cancer patients, by impacting the maturation, activation, immunoregulation, and cytolytic properties of NK cells. Disclosures Thomas: Neumedicines: Employment, Equity Ownership. Lawrence:Neumedicines: Employment, Equity Ownership. Mar:Neumedicines: Employment, Equity Ownership. Kha:Neumedicines: Employment, Equity Ownership. Basile:Neumedicines: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Description: XmAb2513 is a novel second-generation humanized monoclonal antibody (mAb) directed against the human cell surface antigen CD30, with an Fc region engineered to enhance cell killing activity via recruitment of effector cells through increased binding affinity to Fcγ receptors (FcγRs). The CD30 antigen (Ki-1) is a member of the tumor necrosis factor superfamily and was originally identified as a cell surface antigen on primary and cultured Reed-Sternberg cells of Hodgkin Lymphoma (HL). Expression of CD30 is a hallmark for the identification of HL and a subset of T-cell lymphomas, including Anaplastic Large Cell Lymphoma (ALCL). Preclinical in vitro data demonstrated XmAb2513 to be more potent with regards to antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cell-mediated phagocytosis (ADCP) than the first generation anti- CD30 antibodies MDX-060 and SGN-30. Studies in cynomolgus monkeys demonstrated that XmAb2513 exposure was proportional to dose with half-lives (t½) ranging from 5 to 9 days in single dose studies and 12 to 17 days in repeat dose studies. The exposure and t½ data from these cynomolgus monkey studies supported an every other week dosing interval in clinical trials. Based on these favorable features, a Phase 1 study has been initiated to examine the safety and efficacy of XmAb2513 in patients with relapsed and refractory classical HL and ALCL. This ongoing Phase 1 Study is currently evaluating every other week dosing of XmAb2513 using a dose-escalation study design to establish the maximum tolerated dose (MTD). The dose levels under evaluation are 0.3, 1.0, 3.0, 6.0, 9.0, and 12.0 mg/kg, given intravenously over two hours. To date, seven patients are enrolled on the study in the first three dose levels. Pre-study simulation of human exposure based on the pharmacokinetic (PK) parameters obtained from cynomolgus monkeys predicted that 0.3 mg/kg XmAb2513 in humans would result in serum trough levels of 1–1.5 μg/mL after four infusions given every other week. Interim PK and immunogenicity results from the treated patients have been analysed and the results observed thus far are on track with these simulations. Additionally, immunogenicity assessment for human anti-XmAb2513 (HAHA) showed that the treated patients are so far negative for HAHA. Importantly XmAb2513 was well tolerated. As dose escalation continues, results for human PK, immunogenicity, and safety for additional dose cohorts of HL patients, and preliminary safety and response assessment data will be presented.

Description: Interleukin-12 (IL-12) is a heterodimeric cytokine with pleiotropic effects as a potent immunoregulatory molecule and a hematopoietic stimulatory factor. Studies in irradiated non-human primates (NHP) have shown the ameliorating effects of recombinant human IL-12 (HemaMaxTM, rHuIL-12) in a) regenerating hematopoietic tissue following radiation-induced bone marrow ablation, b) lowering the incidence of hemorrhage, and c) decreasing the risk of infections, collectively leading to an increase in NHP survival following lethal radiation exposure. A Phase 1b study was performed in healthy human subjects to evaluate the safety of rHuIL-12 following a single subcutaneously (sc) administered unit dose of 12μg to 32 healthy human subjects. Placebo was administered to 8 subjects. Peripheral blood samples were collected before and after rHuIL-12 administration and up to study day 14. Immunophenotyping of blood cell populations was conducted by Fluorescence Activated Cell Sorting (FACS). rHuIL-12 administration resulted in a transient decrease in peripheral blood mean CD45+ leukocytes, CD45+ lymphocytes, CD45+CD16+CD56+ NK cells, and CD45+CD34+ hematopoietic progenitor cells. Nadirs were reached on day 2, 24 hours after rHuIL-12 administration, for lymphocytes (54.2% reduction from baseline), CD16+CD56+ NK cells (80.4% reduction from baseline), and CD34+ hematopoietic progenitor cells (37.9% reduction from baseline). Cell levels returned to approximately baseline levels on day 5 for CD16+CD56+ NK cells, by day 7 for lymphocytes and CD34+ cells and by day 9 for CD45+leukocytes. Placebo was without effect. Plasma concentrations of IFNγ (Interferon γ) and the chemokine CXCL10 (Interferon γ-induced protein 10), as determined by ELISA, were increased on days 3 and 4 in rHuIL-12-treated subjects. Placebo was without effect. Cell surface expression of IL-12Rβ2, a subunit of the heterodimeric receptor for IL-12, was also studied by flow cytometry. IL-12Rβ2+ NK (CD16+CD56+) cells showed a decrease in levels on day 2, with a reduction of 80.4% from baseline. In addition, the mean fluorescence intensity (MFI) was determined for bright CD56, on NK cells. There was an increase in CD56 MFI for the rHuIL-12-treated subjects, while no effect was seen in the placebo treated subjects. The peak of expression occurred on day 3 (an increase of 55.5%) and had returned to baseline by day 11. Increased CD56 expression is found on a NK subset uniquely equipped to traffic to sites of innate and adaptive immune responses. IL-12, initially called NK cell stimulating factor, can regulate NK cell recruitment to tissues by inducing migration and interaction with endothelial cells. The transient change in IL-12Rβ2+ NK (CD16+CD56+) cells after rHuIL-12 administration, together with the increase in bright CD56+NK cells, suggests that NK cells may be leaving the peripheral blood and migrating into the tissues, fulfilling their role of immune surveillance. Using human peripheral blood mononuclear cells (PBMC) obtained from healthy donors rHuIL-12 was shown by qPCR to induce IFNγ and CXCL10 mRNA expression. Furthermore rHuIL-12 induced a transient upregulation of co-receptors IL-12Rβ2 and CXCR3 (the Gαiprotein-coupled receptor for CXCL10) on lymphocytes, as determined by FACS. Our data indicate that rHuIL-12 administration to healthy human subjects induces IL-12Rβ2+, CD16+CD56+ NK cell migration from the peripheral blood into the tissue compartment, through a mechanism facilitated by IFNγ-induced CXCL10 chemokine and its receptor CXCR3. Further it is likely that this mechanism is the basis for the transient decrease of CD45+ leukocytes, CD45+ lymphocytes, CD45+CD16+CD56+ NK cells, and CD45+CD34+hematopoietic progenitor cells, described above, following rHuIL-12 administration to healthy human subjects. This project has been funded in part with Federal funds from the Biomedical Advanced Research and Development Authority, Office of the Assistant Secretary for Preparedness and Response, Office of the Secretary, Department of Health and Human Services, under Contract No. HHSO100201100037C. Disclosures: Thomas: Neumedicines: Employment. Lawrence:Neumedicines: Employment. Mar:Neumedicines Inc: Employment. Kha:Neumedicines: Employment. Vainstein:Neumedicines Inc.: Employment. Gokhale:Neumedicines Inc.: Employment. Basile:Neumedicines Inc.: Employment, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Patents & Royalties, Research Funding.

Description: XmAb®5574 is an Fc engineered humanized monoclonal antibody (mAb) that binds to the human cell surface antigen CD19 and demonstrates anti-proliferative activity against CD19-positive (CD19+) cell lines. XmAb5574 also has an engineered Fc region to enhance cell killing activity via recruitment of effector cells through increased binding affinity to Fcγ receptors (FcγRs). Consequently, XmAb5574 exhibits superior antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cell-mediated phagocytosis (ADCP), when compared to a native IgG1 (non Fc-engineered) or an Fc knock out (Fc KO; engineered to ablate FcγR interaction) version of the anti-CD19 antibody. To evaluate the potential clinical activity of XmAb5574 in CD19+ B cell malignancies such as non-Hodgkin’s lymphoma (NHL), XmAb5574 was tested in murine subcutaneous (sc) xenograft models using the CD19+ Ramos and Raji human lymphoma cell lines. XmAb5574, administered by intraperitoneal injection (ip, 2qw ×2), gave dose-related inhibition of tumor growth with these models. The efficacy against established sc Ramos tumors was shown to be FcγR-dependent and enhanced by Fc engineering. Fc KO antibodies had no effect at the doses used. Preclinical studies were conducted to evaluate the safety and pharmacokinetics of XmAb5574 in non-human primates. In vitro studies demonstrated that the cynomolgus monkey was an appropriate species for study. XmAb5574 bound to a CD19-expressing cynomolgus monkey cell line and CD20+ peripheral lymphocytes from either cynomolgus monkey or human whole blood samples. Binding affinities of XmAb5574 to both human and cynomolgus monkey FcγRs were evaluated by Biacore methods and were found to be similar. Additionally, XmAb5574 gave similar staining patterns in immunohistochemistry cross-reactivity studies with normal human and cynomolgus monkey tissue panels. Single dose administration of XmAb5574 (0, 0.3, 1.0, 3.0, and 10.0 mg/kg, intravenous [iv] infusion) to cynomolgus monkeys gave an immediate and sustained depletion of peripheral B cells in a dose-dependent manner. B cells were reduced in the bone marrow and lymph node with the spleen showing involuted germinal centers and decreased CD20 immunostaining. B cell recovery, peripherally evident after 57 days, was observed in lymphoid tissues after 85 days. The native anti-CD19 IgG1 (non Fc-engineered) did not induce B cell depletion at 3 mg/kg, in contrast to almost complete B cell depletion by XmAb5574 at the same dose. The pharmacokinetics of XmAb5574 were determined in cynomolgus monkeys after a single iv infusion at 0.3, 1, 3, or 10 mg/kg. Blood samples were collected throughout the study, processed to serum, and XmAb5574 concentration determined using an ELISA method. Exposure was approximately dose proportional for the 1–10 mg/kg dose levels but decreased at the 0.3 mg/kg level indicating dose-dependent clearance for XmAb5574 in this species. Among the 1–10 mg/kg dose levels, the clearance and half-life ranged from 4.3–5.8 mL/day and 7.7–10.7 days, respectively. Single iv infusions of XmAb5574 (0.3–10 mg/kg) were well tolerated in cynomolgus monkeys. These preclinical data provide a rationale for the clinical testing of XmAb5574 in patients with B cell malignancies.

Description: Despite advances in the treatment of leukemia patients, response rates with intensive chemotherapy regimens remain less than 30% for relapsed or refractory acute leukemias and advanced chronic myelogenous leukemias. SNS-595, is a novel naphthyridine analog small molecule, a class of drugs not previously used in cancer treatment. SNS-595 acts specifically during the S-phase of the cell cycle to induce rapid apoptosis of cells that are actively synthesizing DNA, and a subsequent cell cycle arrest in the G2 phase of the cell cycle. Sunesis Pharmaceuticals, Inc., is developing SNS-595 for the treatment of both solid and hematologic malignancies. SNS-595 was previously evaluated in two models of hematologic cancer in nu/nu mice, causing a dose-dependent tumor growth inhibition (97% to 99%, n=6 mice per treatment group) in a LM-3 Jck (human acute lymphoma) hematologic xenograft. All 6 mice treated at 30 mg/kg had a major reduction in tumor volume, with 2 mice showing a complete response. SNS-595 also significantly inhibited tumor growth in mice bearing CCRF-CEM (human acute lymphoblastic leukemia) xenograft tumors. In phase I clinical trials in solid tumors the dose-limiting toxicity was neutropenia, and the incidence of gastrointestinal effects, nausea, and vomiting was low. No mucositis or peripheral neuropathies were observed. In the present study, CD1 mice (n=4 per treatment group) were administered either SNS-595 15 mg/kg or 20 mg/kg, by IV bolus on days 0 and 4, or the S-phase acting drug, cytarabine (Ara-C) 150 mg/kg, BID, by IP injection on days 0 and 4. SNS-595 was well tolerated, with no body weight loss observed through to day 16. Bone marrow isolated from the femurs showed a dose-dependent reduction in cellularity on day 6, 48hr after the second of the two SNS-595 administrations; at 15 and 20 mg/kg, cellularity was reduced to 15% (±2.9, n=4) and 7.5% (±1.4, n=4) respectively. SNS-595, 20 mg/kg, reduced absolute neutrophils to a nadir of 51 ±24 cells/μL blood (n=4) on day 8, from 1244 ±55 cells/μL at day 0 (n=4), but subsequently rebounded to normal levels by day 16. Total WBCs also reached a nadir on day 8, returning to normal by day 16. In the same timeframe cytarabine caused bone marrow ablation, with absolute neutrophil counts substantially reduced at day 8 and returning to normal by day 16. In conclusion SNS-595 has significant anti-tumor activity in hematologic xenografts, as well as significant ability to reversibly ablate murine bone marrow cells. These properties, combined with the good clinical safety profile observed in phase I patients, suggest that SNS-595 has the potential to demonstrate anti-tumor activity in patients with hematologic malignancies.