Abstract Background: CD3-targeting T cell engagers (TCE) have been approved as therapy for various hematological and solid tumor oncology indications; however, they can often induce unwanted safety issues, including cytokine release syndrome (CRS) and liver enzyme elevations. TAK-280 is an investigational B7-H3 x CD3ε conditional bispecific redirected activation (COBRA) TCE. In its masked prodrug form, TAK-280 binds to B7-H3, but not to CD3ε. Once in the protease-rich tumor microenvironment, proteases mediate cleavage of the linker resulting in unmasking the prodrug, which allows for the formation of active CD3ε-binding dimers and ultimately CD3 T-cell activation and cytotoxic anti-tumor response against co-engaged B7-H3 expressing cells. We developed a mechanistic PK/PD modeling framework to describe the PK and safety of TAK-280, based on clinical data from a Phase 1 dose escalation study (NCT05220098) investigating TAK-280 for the treatment of patients with advanced, unresectable or metastatic cancer, with a focus on tumor types with enhanced B7-H3 expression. Methods: In the tumor compartment of the model, TAK-280 binds to B7-H3 expressed on tumor cells. Once the dimer is formed, it binds to CD3 to form the desired trimer complex composed of TAK-280, B7-H3 and CD3. It is assumed that this trimer complex is the only species that triggers cytokine release in the tumor compartment. Once cytokines are secreted in the tumor, they are assumed to move to systemic circulation. In the central compartment, cytokines undergo basal production and degradation. Results: A two-compartment model with linear elimination was sufficient to describe the PK. Cytokine dynamics were described using a three-population immune cell pool[1] (non-secreting, secreting and refractory) framework. Immune cell dynamics reveal that the cytokine Cmax attenuation over time is a consequence of immune cell de-sensitization by transitioning to the refractory state. This concept of de-sensitization or decreased cytokine release following TCE dosing is clinically well established and mechanistically it is attributed to fewer non-secreting immune cells that are available by the time the top dose is administered (in a lead-in dosing regimen). Conclusion: Using the model, we were able to show that lead-in dosing led to lower cytokine peak concentrations and therefore predicted lower probability for an adverse event. Model simulations demonstrated comparable safety outcomes for both QW and BIW dosing of the bispecific antibody. References: 1.Weddell et. al. CPT Pharmacometrics Syst Pharmacol. 2023; 12:1726-1737 Citation Format: Agnish Dey, Tao Long, Sabrina Collins, Dean Bottino, Jaydeep Srimani, John Gibbs. QSP modeling to inform dose and regimen selection for TAK-280: A bi-specific antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1825.

Interferon alfa has activity against multiple myeloma (MM). Modakafusp alfa is an immunocytokine comprising 2 attenuated interferon alfa-2b molecules and an anti-CD38 immunoglobulin G4 antibody, targeting delivery of interferon alfa to CD38-expressing (CD38+) immune and myeloma cells. This phase 1/2 trial enrolled patients with relapsed/refractory multiple myeloma with >= 3 prior lines of treatment and refractory to, or intolerant of, >= 1 proteasome inhibitor and >= 1 immunomodulatory drug. During dose escalation, modakafusp alfa was administered at 10 doses in 4 schedules across 13 cohorts. The primary end point was safety for dose escalation, and overall response rate (ORR) for dose expansion. We enrolled 106 patients who had received a median of 6.5 lines of prior therapy; 84% of patients had myeloma previously refractory to an anti-CD38 antibody. The most feasible dosing schedule was every 4 weeks (Q4W), at which the maximum tolerated dose was 3 mg/kg. Among 30 patients treated at 1.5 mg/kg Q4W, the ORR was 43.3%, with a median duration of response of 15.1 months (95% confidence interval [CI], 7.1-26.1); median progression-free survival was 5.7 months (95% CI, 1.2-14). Grade >= 3 adverse events (AEs) occurred in 28 (93.3%) patients, the most common were neutropenia (66.7%) and throm bocytopenia (46.7%); infections were reported in 8 (26.7%) patients (including grade 3 in 4 [16.7%]). Modakafusp alfa therapy induced upregulation of the type 1 interferon gene signature score, increased CD38 receptor density in CD38+ cells, and innate and adaptive immune cell activation. Modakafusp alfa resulted in antitumor activity and immune activation in patients with MM. AEs were primarily hematologic. This trial was registered at www.clinicaltrials.gov as #NCT03215030.

Recombinant interferon alpha (IFNα) has been used to treat cancer patients for over 30 years; however, its clinical utility has been limited by a narrow therapeutic index. Given the recognized anti-tumor and immunomodulatory impacts of IFNα, the development of novel strategies to harness these attributes while minimizing associated toxicity could provide significant benefit for patients. The concept of attenuating IFNα binding affinity for its receptor was conceived to address this challenge and led to the development of CD38-targeted Attenukine™, a CD38-targeted antibody attenuated IFNα immunocytokine. In this study, we sought to delineate the effects of targeting AttenukineTM specifically to tumor cells and/or immune cells using an antibody to CD38, a cell surface glycoprotein expressed on certain tumor and immune cells, using different mouse models and anti-human or anti-mouse CD38-targeted Attenukine™. Our results demonstrate that an anti-human CD38 AttenukineTM inhibits tumor growth through direct anti-proliferative effects of IFNα on CD38 + tumor cells as well as by indirectly modulating the anti-tumor immune response. In various in vivo models leveraging syngeneic mice bearing tumors with or without CD38 expression, administration of CD38-murine AttenukineTM mediated anti-tumor efficacy with increased immune activation and intra-tumoral infiltration. These data point to a potential dual mechanism of action for CD38-targeted Attenukine™, involving both tumor- and immune-directed effects, and highlight the potential benefit of a CD38-targeted attenuated IFNα therapy to deliver the known effects of IFNαtreatment to a broad spectrum of patients, while limiting the toxicity typically associated with recombinant IFNα.

BackgroundModakafusp alfa is a novel immunocytokine comprising two attenuated interferon-α2b molecules fused to an anti-CD38 IgG4 monoclonal antibody. Modakafusp alfa has shown immune cell activation and antitumor activity in preclinical mouse models, including in combination with an anti-programmed cell death (PD-1) receptor in tumors that do not express CD38, and demonstrated clinical responses and immune activation in patients with relapsed/refractory multiple myeloma.MethodsIn phase Ib, adult patients with advanced/metastatic solid tumors received escalating doses of modakafusp alfa 0.1–1.5 mg/kg intravenously every 3 weeks (Q3W) across six dosing cohorts. In phase II, patients with unresectable/metastatic cutaneous melanoma and resistance to ≤2 anti-PD-1 therapies in the metastatic setting received modakafusp alfa 1 mg/kg Q3W in combination with pembrolizumab Q6W. Primary objectives were to determine the safety/tolerability as a single agent in phase I, and efficacy in combination with pembrolizumab in phase II.ResultsA total of 21 and 24 patients were enrolled across phases Ib and II, respectively. The recommended phase II dose of modakafusp alfa was 1 mg/kg. The most common drug-related adverse events were infusion-related reactions (IRRs; 52.4%) and thrombocytopenia (28.6%) in phase Ib; and headache (58.3%), fatigue (54.2%), IRRs (41.7%), neutropenia (37.5%), and nausea (33.3%) in phase II. In phase Ib, seven patients had a best response of stable disease (SD); in phase II, one patient had a confirmed complete response, one had a confirmed partial response, and seven had SD. All immunogenicity-evaluable patients were anti-drug antibodies (ADAs) positive following treatment with modakafusp alfa; neutralizing ADAs were reported in 82.4% and 90.9% of patients in phases Ib and II, respectively, which was associated with drug exposure reduction. Pharmacodynamic analyses demonstrated innate and adaptive immune activation in peripheral blood and within tumors. Paired biopsy analysis revealed two subgroups of patients defined by differences in CD38 upregulation, accompanied by differential intratumoral pharmacodynamic changes. Correlative analysis was inconclusive.ConclusionsModakafusp alfa induces innate and adaptive immune responses, supporting its hypothesized mechanism of action (MoA) in patients with advanced solid tumors. High immunogenicity and the potentially limited treatment effect of the interferon MoA may have contributed to limited efficacy in these patients.Clinical trial registrationhttps://clinicaltrials.gov/study/NCT04157517, identifier NCT04157517.

Interferon-alpha has activity against multiple myeloma. Modakafusp alfa is an immunocytokine comprising two attenuated interferon-alpha2b molecules and an anti-CD38 IgG4 antibody, targeting delivery of interferon-alpha to CD38+ immune and myeloma cells. This phase I/II trial (NCT03215030) enrolled patients with relapsed/refractory multiple myeloma with ≥3 prior lines of treatment and refractory to or intolerant of ≥1 proteasome inhibitor and ≥1 immunomodulatory drug. During dose escalation, modakafusp alfa was administered at ten doses in four schedules across 13 cohorts. The primary endpoint was safety for dose escalation, and overall response rate for dose expansion. We enrolled 106 patients who had received a median of 6.5 lines of prior therapy; 84% of patients had myeloma previously refractory to an anti-CD38 antibody. The most feasible dosing schedule was every 4 weeks (Q4W), at which the maximum tolerated dose was 3 mg/kg. Among 30 patients treated at 1.5 mg/kg Q4W, the overall response rate was 43.3%, with a median duration of response of 15.1 months (95% CI, 7.1-26.1); median progression-free survival was 5.7 months (95% CI, 1.2-14.0). Grade ≥3 adverse events occurred in 28 (93.3%) patients, the most common were neutropenia (66.7%) and thrombocytopenia (46.7%); infections were reported in 8 (26.7%) patients (including grade 3 in 4 [16.7%]). Modakafusp alfa therapy induced upregulation of the type I interferon gene signature score, increased CD38 receptor density in CD38+ cells, and innate and adaptive immune cell activation. Modakafusp alfa resulted in anti-tumor activity and immune activation in patients with multiple myeloma. Adverse events were primarily hematologic.

Abstract Background: Modakafusp alfa (moda), a novel immunocytokine, is an innate immune enhancer comprising an anti-CD38 IgG4 antibody fused to 2 attenuated interferon (IFN) α2b molecules. Moda is being evaluated in phase 1/2 trials for multiple myeloma and in a phase 1/2 trial in solid tumors. Here, we present PD data in tumor biopsies and peripheral blood (PB) from the phase 1/2 study of moda as monotherapy in pts with advanced/metastatic solid tumors (NCT04157517). Methods: A total of 21 pts were treated with moda 0.1-1.5 mg/kg every 3 weeks. Tumor biopsy samples were collected at screening and on cycle 2, day 2 (C2D2). Biopsies were evaluated by multiplex immunofluorescence (using a Multiomyx platform) and RNASeq. PB samples were collected pre-dose on C1D1 and at timepoints after treatment. PB samples were evaluated by CyTOF to assess PD changes in immune cells. Results: No clinical tumor responses (partial or better) were observed in the 21 pts. Analysis of tumor biopsies revealed two subgroups defined by differences in upregulation of CD38 expression after moda treatment, with differential intratumoral PD changes. The CD38 gene has IFN response elements within its promoter region. Thus, correlation of tumor PD with changes in CD38 expression is of interest because, along with being a target of moda, an increase in CD38 expression may indicate drug activity in the tumor microenvironment. Interestingly, in the subset of pts in whom an increase in the percentage of CD38+ lymphocytes in response to moda was reported, there were also increases in CD8 and CD4 T cell activation, (%CD69) as well as CD8 T cell cytotoxic function (%GzB). Additionally, moda led to increase in CD14+CD16+ intermediate monocytes, indicating an enhanced myeloid response in several pts, and minimal changes in FoxP3+ Tregs regardless of changes in CD38 expression. Moda treatment led to an increase in activated and cytolytic natural killer (NK) and CD8 T cells in all pts. This was accompanied by increased NK and CD8 T cell proliferation (%Ki67) in PB, without sustained increase in exhaustion markers. CD4 T cells were also activated in response to moda and there was no increase in circulating FoxP3+ Tregs. Enhanced myeloid cell response, measured by increased proliferation of monocytes and dendritic cells, along with upregulation of costimulatory molecules, were also seen. Importantly, immune PD changes in the PB were seen in most pts and there were no immune PD differences identified between the two patient subsets defined in the biopsy analysis. Conclusion: PD biomarker data from this phase 1/2 trial in pts with advanced solid tumors demonstrated that moda enhances innate and adaptive immune activation in PB and within tumors. The presence of a differential intratumoral PD response in a subset of pts with elevated CD38+ cells highlights that tumor intrinsic factors may play a role in driving moda’s activity in tumors. Citation Format: Gurpanna Saggu, Janet L. Markman, Min Young Lee, Faith Dunbar, Adarsh Joshi, Shining Wang, Sabrina Collins. Modakafusp alfa shows intratumoral immune pharmacodynamics (PD) in a subset of patients (pts) in a phase 1b study in advanced/metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT065.

Modakafusp alfa (moda), a novel immunocytokine, is an innate immunity enhancer comprising two attenuated interferon (IFN) α2b molecules fused to an anti-CD38 IgG4 monoclonal antibody backbone, driving preferential IFNα signalling in CD38-expressing innate and adaptive immune cells as well as myeloma cells. Here, we present pharmacodynamic (PD) data from the first-in-human Phase 1/2 study of moda as a monotherapy in patients with RRMM (iinnovate-1; NCT03215030). A total of 37 patients treated with moda at 1.5 or 3 mg/kg every 4 weeks were included in the analysis. Peripheral blood (PB) and bone marrow (BM) samples were collected during screening or pre-dose on cycle 1 day 1 (C1D1) and at multiple timepoints after treatment. BM and PB samples were evaluated by cytometry time of flight (CyTOF) and bulk RNA sequencing (RNAseq) to assess pharmacodynamic changes in immune cell populations, cell activation, and gene expression. Administration of moda led to enhanced innate immune cell activation and cytotoxic function as demonstrated by increased proportions of CD69+ and granzyme B+ in peripheral NK cells analyzed by CyTOF. This was accompanied by a decrease in the proportion of TIGIT+ NK cells, indicating reduced inhibitory signaling. Furthermore, enhanced proliferation (%Ki67+) of NK cells was observed in both BM and PB. Moda also impacted myeloid cell populations in BM and PB. Dendritic cells (DCs) and monocytes in PB showed increased surface expression of the co-stimulatory molecule CD86, suggesting a potential for enhanced antigen presentation and co-stimulation ability. Increased proliferation (%Ki67) of DCs and monocytes was detected in both PB and BM, accompanied by a decrease in numbers of peripheral DCs which may indicate recruitment or homing to secondary lymphoid organs. Additionally, RNAseq analysis revealed that treatment with moda led to upregulation of CD68 expression in both PB and BM, indicating a proinflammatory M1 macrophage type response. Finally, CyTOF analysis also indicated that moda significantly impacted adaptive immunity. We observed enhanced activation (%CD69, %PD1 and %CD40L) and cytotoxic function (%granzyme B) of peripheral CD8 T cells, and increased CD8 T cell proliferation (%Ki67 CD8) in both PB and BM samples. Enhanced activation of peripheral CD4 T cells (%CD69, %CD40L) was also detected. Consistent with activation of the adaptive immune system, there was a reduction in naïve CD8 T cells accompanied by an increase in CD8 T effector memory cells in PB. Analysis of exhaustion markers (TIGIT, PD-1) in cycle 1 (C1D8, C1D15, and C2D1 predose) showed that moda did not induce CD8 T cell exhaustion in either PB or BM, and there was no change in FoxP3+ Treg cells. Moda-induced innate and adaptive immune cell phenotypic changes were evaluated for correlation with clinical response at timepoints with sufficient number of evaluable samples. While none of the associations were statistically significant after correcting for multiplicity testing (using the false discovery rate method), we observed trends warranting further investigation. There was a greater increase of CD40L+ NK cells and PD1+ CD8 cells in responders vs. non-responders at C1D2. Additionally, at C1D15 responders showed a lower increase in proliferation (%Ki67+) of classical monocytes, NK cells, and myeloid DCs in PBas compared to non-responders. A similar trend was also observed in the BM classical monocytes. Even though the peak of Ki67 expression was observed at C1D8, diminished increases of proliferating cells at C1D15 in responders was a surprising observation that needs further consideration. The PD biomarker data from this first-in-human clinical trial demonstrated that treatment with moda enhances both innate and adaptive immune cell activation in PB and BM. Importantly, moda-mediated immune activation did not result in T cell exhaustion during cycle 1, as evaluated in both PB and BM. We have observed interesting trends of immune phenotypic changes that may correlate with response. Follow-up analyses of the correlation of biomarkers with clinical response are in progress and will be presented. Further clinical trials are underway (iinnovate-2, NCT05556616; iinnovate-3, NCT05590377) to evaluate moda's novel immune activating mechanism in combination with standard of care anti-myeloma therapies.

2503 Background: Modakafusp alfa (TAK-573) is a first-in-class immune-targeting attenuated cytokine designed to deliver attenuated interferon alpha-2b (IFNα2b) moieties to CD38-expressing cells. It consists of two attenuated IFNα2b molecules genetically fused to the Fc portion of a humanized, anti-CD38, IgG4 monoclonal antibody. Specificity for CD38 and reduced IFN receptor binding affinity of the attenuated IFNα2b molecules significantly reduces the potential for off-target binding and toxicity. Modakafusp alfa has demonstrated immune cell activation and antitumor activities in preclinical mouse models, including tumor models that do not express CD38, and has shown strong clinical responses and immune activation in pts with refractory/relapsed multiple myeloma. The dose-escalation phase of this phase 1b/2 study (NCT04157517) investigated safety, pharmacokinetics, immunogenicity, pharmacodynamics (PD), and preliminary efficacy of modakafusp alfa in metastatic solid tumors. Methods: Adult pts with advanced/metastatic solid tumors received modakafusp alfa IV on day 1 of a 21-day cycle (Q3W). Dose escalation started at 0.1 mg/kg and proceeded based on cycle 1 safety data via a Bayesian model with overdose control principles. Results: Twenty-one pts were dosed in the escalation phase at 0.1 (n = 3), 0.2 (n = 3), 0.4 (n = 3), 0.75 (n = 3), 1.0 (n = 3), and 1.5 mg/kg (n = 6) Q3W; median age 63 y (range 42–80); male 57.1%; GI malignancies 71.4%; median prior lines of therapy 3 (range 2–7). Two pts had dose-limiting toxicities in cycle 1 at 1.5 mg/kg; 1 pt with baseline bone infiltration had grade 4 thrombocytopenia and 1 pt had grade 3 confusion. As of Nov 2021, across all doses, pts received a median of 2 treatment cycles (range 1–11). Modakafusp alfa treatment-related adverse events (TRAEs) reported in 81% of pts included infusion-related reactions (52.4%), chills (47.6%), and nausea (33.3%). Grade ≥3 TRAEs reported in 42.9% of pts included neutropenia (14.3%) and hypertension (9.5%). There was a greater than dose proportional exposure increase in the dose range 0.1–1.5 mg/kg, with no exposure accumulation after Q3W dosing. Incidence rate of post-treatment anti-drug antibody (ADA) was 100%. PD data suggested saturation of peak IFN pathway modulation at ≥0.2 mg/kg in the peripheral blood with duration of modulation increasing with dose. Among the 14 response-evaluable pts, 7 had best response of stable disease, including 1 with cutaneous melanoma who had 21% target lesion reduction. Conclusions: Modakafusp alfa had a manageable safety profile in the dose range 0.1–1.5 mg/kg in pts with solid tumors. Proof of mechanism was validated. The recommended phase 2 dose was determined as 1.0 mg/kg Q3W based on assessment of holistic data and will be tested in combination with a checkpoint inhibitor in selected tumor types. Characterization of ADA and its impact is ongoing. Clinical trial information: NCT04157517.

Background Despite recent success of monoclonal antibodies (mAb) and T cell redirecting therapies, relapsed/refractory (RR) multiple myeloma (MM) patients remain in urgent need of new therapies with distinct mechanisms of action (MoA). Modakafusp alfa, previously known as TAK-573, is a novel immune-targeted attenuated cytokine specifically designed to deliver interferon-alpha to CD38-expressing cells via a CD38-targeting IgG4 mAb. Preliminary results of a first in human phase 1 trial with modakafusp alfa monotherapy (1.5mg/kg, every four weeks) in RRMM patients (90% anti-CD38 mAb refractory; 37% anti-BCMA agent exposed) indicate a promising 40% overall response with manageable toxicity (Kaufman et al. EHA 2022 abstract S181). Prior studies suggest a unique and multimodal MoA of modakafusp alfa, including anti-proliferative effects on tumor cells as well as stimulation of CD38-positive immune effector cells. Towards a thorough understanding of these immunomodulatory effects, specifically regarding the activation of innate immunity, we here studied the effects of modakafusp alfa on the anti-MM activity of NK cells, which highly express CD38. Aims We assessed the ex vivo activity of modakafusp alfa on NK cell activation, degranulation, and antibody-independent cytotoxicity. In addition, we investigated the impact of modakafusp alfa on NK cell-mediated, antibody-dependent cellular cytotoxicity (ADCC) against MM cells using daratumumab (anti-CD38) or elotuzumab (anti-SLAMF7). Methods NK cell activation was explored by flow cytometry after 24-hour incubation of peripheral blood mononuclear cells (PBMC) from healthy donors with modakafusp alfa or negative/specificity controls. These pre-incubated PBMCs were also used to examine NK cell degranulation after subsequent 4 hour stimulation with K562 or PMA/Ionomycin, or in a 16-hour cytotoxicity assay against K562. In addition, modakafusp alfa pre-incubated PBMCs or enriched NK cells were assessed for antibody-independent cytotoxicity or daratumumab/elotuzumab-mediated ADCC in 24-48 hour assays against MM cell lines RPMI-8226, MM.1S or UM9. Alternatively, modakafusp alfa was directly added to the assays without pre-incubation steps. Results We found that incubation of PBMCs with modakafusp alfa for 24 hours resulted in upregulation of activation markers CD38 and CD69 on the surface of NK cells. In addition, modakafusp alfa pre-incubation significantly improved the degranulation of NK cells after 4-hour stimulation with K562 or PMA/Ionomycin. Importantly, overnight pre-incubation of PBMCs or enriched NK cells with modakafusp alfa showed enhanced antibody-independent cytotoxicity against K562 tumor cells and MM cell lines RPMI-8226, MM.1S or UM9. Consequently, this also resulted in augmented killing of MM cells in the presence of daratumumab or elotuzumab. We observed similar effects when modakafusp alfa was directly added to the cytotoxicity assays without pre-incubation of immune effector cells. Conclusions Modakafusp alfa rapidly activates NK cells, and improves their degranulation and anti-MM effectivity. This important MoA also results in improved efficacy of daratumumab or elotuzumab in short-term cytotoxicity assays. Our findings warrant clinical investigation of combining modakafusp alfa with NK cell-exploiting immunotherapies.

Introduction Modakafusp alfa is a first-in-class, immune-targeting, attenuated cytokine. It consists of 2 attenuated interferon (IFN)α2b molecules genetically fused to the Fc portion of an anti-CD38 IgG4 monoclonal antibody (mAb), allowing targeted delivery of IFNα to innate and adaptive immune cells, as well as myeloma cells. We previously reported preliminary results from a cohort of 30 pts who received modakafusp 1.5 mg/kg every 4 weeks (Q4W) in this phase 1/2 study (NCT03215030) (Kaufman EHA 2022, S181). We now report the final safety and efficacy results of the study (parts 1 and 2), including minimal residual disease (MRD) status. Methods Pts had received ≥3 prior lines of treatment and were refractory to or intolerant of ≥1 proteasome inhibitor and ≥1 immunomodulatory drug. During dose escalation, modakafusp was administered intravenously at 10 dose levels between 0.001-6 mg/kg; weekly (QW; cycles 1-2 only; 0.001-0.75 mg/kg), every 2 weeks (Q2W; 0.2-0.3 mg/kg), every 3 weeks (Q3W; 0.4-0.75 mg/kg), or Q4W (0.75-6 mg/kg). As anti-myeloma response was detected during dose escalation, expansion cohorts were opened at 0.4 mg/kg Q3W and 1.5 mg/kg Q4W as a single agent. As dexamethasone (dex) is part of standard of care in MM, but could counteract the immune activation elicited by modakafusp, additional cohorts at 0.4 mg/kg Q3W and 1.5 mg/kg Q4W in combination with 40 mg dex QW were opened. Bone marrow aspirates (BMA) for MRD evaluation were collected at screening and at suspected CR and were assessed utilizing the clonoSEQ® next generation sequencing assay at a threshold of 10-5. Peripheral blood samples were collected and evaluated for CD38 receptor density determination by flow cytometry. Results At data cut-off (April 2022), 100 pts had been treated with modakafusp; 56 pts in dose escalation and 44 pts in expansion cohorts. During dose escalation, dose-limiting toxicities were reported with QW and Q2W dosing schedules. In the Q4W dosing schedule, the maximum tolerated dose (MTD) of modakafusp was exceeded at 6 mg/kg due to a grade (G) 3 infusion-related reaction (IRR) in 1 pt and a prolonged thrombocytopenia and neutropenia in 1 pt; the MTD was therefore determined as 3 mg/kg Q4W. During dose escalation, PRs were reported with 0.1 mg/kg and 0.4 mg/kg QW (n=1 each), an unconfirmed VGPR was observed with 0.4 mg/kg Q3W, and PRs (n=3) and a CR (n=1) were reported with 1.5-6 mg/kg Q4W. During expansion, of 8 pts receiving modakafusp 0.4 mg/kg Q3W, 5 had SD and 3 had PD. Of 3 pts in the 0.4 mg/kg Q3W + dex cohort, 2 had SD and 1 had PD. Among 30 pts treated with modakafusp 1.5 mg/kg Q4W (5 in dose escalation and 25 in expansion), the ORR was 43% (Table), median time to response was 1.2 months, and median duration of response was not reached (range 1.0-18.9 months). Median progression-free survival was 5.7 months (95% confidence interval 1.2-15.9). At 1.5 mg/kg Q4W, G≥3 treatment-emergent adverse events (TEAEs) occurred in 26 (87%) pts, including neutropenia (n=19, 63% [G4 n=9, 30%]), thrombocytopenia (n=14, 47% [G4 n=6, 20%]), and lymphopenia (n=11, 37% [G4 n=7, 23%]); 3 (10%) pts had G3 infections, and 1 (3%) pt had a G3 bleeding event. Except for 1 report of G4 hyperuricemia, there were no G4 non-hematological TEAEs; IRRs occurred in 11 pts (37% [G3 n=1, 3%]). Of 8 pts treated with modakafusp 1.5 mg/kg Q4W + dex, 1 pt had a VGPR and 1 pt had SD (1 pt was not evaluable and 5 pts had no post-baseline response assessment). At 1.5 mg/kg Q4W + dex, G≥3 TEAEs occurred in 7 (88%) pts, including thrombocytopenia (n=4, 50% [G4 n=1, 13%]), anemia (n=2, 25%), lymphopenia (n=2, 25% [G4 n=1, 13%]), pneumonia (n=2, 25%), and neutropenia (n=1, 13%). IRRs occurred in 2 pts (25%, none G≥3). Of 4 pts treated at 1.5 mg/kg Q4W with MRD samples collected at screening and suspected CR, 1 pt was MRD- at 10-5. Preliminary analysis showed no correlation between CD38 receptor density on peripheral blood immune cells and clinical response. Further evaluation to explore the association between clinical response and CD38 receptor density on MM cells within BMAs is underway. Conclusions Modakafusp alfa has a novel mechanism of action, a manageable safety profile, and encouraging anti-myeloma activity at 1.5 mg/kg Q4W, independent of peripheral blood immune cell CD38 expression. A randomized phase 2 study to compare fixed-dose levels of 120 and 240 mg (equivalent to 1.5 and 3.0 mg/kg) Q4W and to define the single-agent dose with the optimal benefit/risk profile is currently enrolling. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract Background: Modakafusp alfa (previously known as TAK-573) is a first-in-class immunocytokine designed to deliver interferon alpha-2b (IFNα2b) to CD38+ cells. It consists of two attenuated IFNα2b molecules genetically fused to the Fc portion of a humanized, anti-CD38, IgG4 monoclonal antibody (mAb). The specificity for CD38 and reduced IFN receptor binding affinity of the attenuated IFNα2b molecules significantly reduces the potential for off-target binding and toxicity. Furthermore, modakafusp alfa binds to a different epitope on CD38 than the currently approved anti-CD38 therapeutic mAbs, daratumumab and isatuximab. Preclinical evaluation of modakafusp alfa supports activation of type I IFN signaling in CD38+ cells, inducing direct anti-proliferative effects on myeloma cells, as well as direct and indirect immune cell activation. We have previously reported preliminary results from the first 59 patients (pts) in our first-in-human phase 1 trial of modakafusp alfa in pts with relapsed/refractory multiple myeloma (RRMM; NCT03215030), showing responses to single-agent therapy with doses starting at 0.1 mg/kg weekly; thrombocytopenia and neutropenia were dose-limiting toxicities when modakafusp alfa was administered weekly (QW), every 2 weeks (Q2W), and every 3 weeks (Q3W) (Vogl, Blood 2020). Here we report updated results from this trial, focusing on results from an expansion cohort with dosing every 4 weeks (Q4W). Methods: Eligible pts with RRMM who had received at least three previous lines of treatment received modakafusp alfa as a 1- to 4-hour intravenous infusion at 11 dose levels from 0.001 to 6 mg/kg following a 3+3 dose-escalation design. The initial dosing schedule was QW for 8 doses, then Q2W for 8 doses, and then monthly; subsequent cohorts evaluated dosing Q2W, Q3W or Q4W. Expansion cohorts were planned using modakafusp alfa at protocol-defined, biologically active doses that did not exceed the maximum tolerated dose (MTD). Results: As of May 2021, 83 pts had been treated across all planned dosing schedules. With Q4W dosing, the MTD was exceeded at the 6 mg/kg dose due to DLTs: a grade 3 infusion reaction and prolonged thrombocytopenia and neutropenia, which delayed the start of cycle 2 by >14 days. In total, 24 pts were treated with 1.5 mg/kg modakafusp alfa Q4W (5 pts during dose escalation and 19 pts in an expansion cohort). Analyses include data from all 24 pts. The median number of prior lines of therapy received was 6 (range 4-16); 21 pts (88%) were refractory to an anti-CD38 mAb, and 20 (83%) were triple class-refractory (to a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 mAb). Grade 3 or higher treatment-emergent adverse events (TEAEs) were reported in 18 pts (75%). The most frequent grade 3-4 TEAEs were neutropenia in 12 pts (50%; grade 4 in 6 [25%]), leukopenia in 9 (38%), decreased lymphocyte count in 9 (38%), anemia in 8 (33%), and thrombocytopenia in 8 (33%; grade 4 in 3 [13%]). One pt (4%) had a grade 3 bleeding event and continues on study treatment; 3 pts (13%) had infections (grade 3 in 2 [8%]); and 8 (33%) had infusion reactions (grade 3 in 1 [4%]). The overall response rate (ORR, ≥partial response [PR]) was 42% (complete response [CR], n=2; very good partial response [VGPR], n=5; PR, n=3), and the clinical benefit rate (ORR + minimal response [MR]) was 54% (MR, n=3). Median progression-free survival was 5.7 months (95% confidence interval [CI], 1.9-not reached [NR]), median time to response was 1.9 months (95% CI, 0.95-NR), and median duration of response was 7.4 months (95% CI, 2.3-NR). Among the 21 anti-CD38 mAb-refractory pts, the ORR was 43%, while among the 4 pts who received an anti-CD38 mAb in their most recent line of therapy prior to enrollment, the ORR was 75% (CR, n=1; VGPR, n=2). Correlative studies show evidence of T-cell and natural killer-cell activation, as well as activation of IFN signaling in CD38+ cells, including upregulation of CD38 expression. Conclusion: Modakafusp alfa (TAK-573) is a novel candidate for the treatment of RRMM, which has shown promising anti-myeloma activity in heavily pretreated pts, including anti-CD38 mAb-refractory pts and those who have received an anti-CD38 mAb in their most recent line of treatment. A Q4W dosing schedule of modakafusp alfa is feasible and the optimal dose and potential combinations are being explored. Disclosures Vogl: Takeda: Consultancy, Research Funding; Karyopharm: Consultancy; GSK: Consultancy; Oncopeptides: Consultancy; Janssen: Consultancy; Sanofi: Consultancy; CSL Behring: Consultancy; Active Biotech: Research Funding. Kaufman: Genentech, AbbVie, Janssen: Consultancy, Research Funding; Amgen: Research Funding; Janssen: Honoraria; Roche/Genetech, Tecnopharma: Consultancy, Honoraria; Fortis Therapeutics: Research Funding; Novartis: Research Funding; Incyte, celgene: Consultancy; Sutro, Takeda: Research Funding; Tecnofarma SAS, AbbVie: Honoraria; BMS: Consultancy, Research Funding; Incyte, TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Heidelberg Pharma: Research Funding. Holstein: Oncopeptides: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech, GSK, Janssen, Secura Bio, Sorrento: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Atrash: AMGEN: Research Funding; Jansen: Research Funding, Speakers Bureau; GSK: Research Funding. Nadeem: Takeda: Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees. Janakiram: Kyowa Kirin Therapeutics: Honoraria; Takeda Pharmaceuticals: Research Funding; FATE Therapeutics: Research Funding; ADC Therapeutics: Research Funding. Suryanarayan: Takeda: Current Employment. Liu: Takeda: Current Employment. Parot: Takeda Pharmaceuticals: Current Employment. OffLabel Disclosure: Modakafusp alfa (TAK-573) is a first-in-class immunocytokine consisting of 2 attenuated interferon alpha-2b molecules genetically fused to an anti-CD38, IgG4 monoclonal antibody. This abstract contains information about investigational use of modakafusp alfa in patients with relapsed/refractory multiple myeloma. Safety and efficacy have not been determined.

Drug development in oncology commonly exploits the tools of molecular biology to gain therapeutic benefit through reprograming of cellular responses. In immuno-oncology (IO) the aim is to direct the patient's own immune system to fight cancer. After remarkable successes of antibodies targeting PD1/PD-L1 and CTLA4 receptors in targeted patient populations, the focus of further development has shifted toward combination therapies. However, the current drug-development approach of exploiting a vast number of possible combination targets and dosing regimens has proven to be challenging and is arguably inefficient. In particular, the unprecedented number of clinical trials testing different combinations may no longer be sustainable by the population of available patients. Further development in IO requires a step change in selection and validation of candidate therapies to decrease development attrition rate and limit the number of clinical trials. Quantitative systems pharmacology (QSP) proposes to tackle this challenge through mechanistic modeling and simulation. Compounds' pharmacokinetics, target binding, and mechanisms of action as well as existing knowledge on the underlying tumor and immune system biology are described by quantitative, dynamic models aiming to predict clinical results for novel combinations. Here, we review the current QSP approaches, the legacy of mathematical models available to quantitative clinical pharmacologists describing interaction between tumor and immune system, and the recent development of IO QSP platform models. We argue that QSP and virtual patients can be integrated as a new tool in existing IO drug development approaches to increase the efficiency and effectiveness of the search for novel combination therapies.

Abstract Background: Despite improvements in outcome for patients treated with triplet and quadruplet based regimens, multiple myeloma is still a relapsing and ultimately fatal disease. We previously reported that targeting an investigational attenuated form of IFNα, or Attenukine™, to multiple myeloma (MM) tumor cells via direct fusion to an anti-CD38 antibody (TAK-573) has direct anti-proliferative activity on MM cancer cells in vitro and induces robust and durable responses in MM xenograft tumor models, alone and in combination with standard-of-care (SOC) agents. Here, we further elucidate the broad immunomodulatory impact and antitumor activity of a murine reactive version of TAK-573, anti-mouse CD38-attenuated murine IFNα (mCD38-mATT), alone and in combination with SOC agents in immunocompetent murine tumor models of MM. Methods: Murine CD38 receptor expression and direct sensitivity to murine IFNα (mIFNα) of 2 murine MM cell lines were characterized. Murine MM cell line-derived tumor models were established in immunocompetent mice and antitumor activity of mCD38-mATT treatment was evaluated alone and in combination with approved SOC agents for MM. Pharmacodynamic changes in the tumor immune microenvironment post-treatment were determined using multicolor flow cytometry. Results: Both MM murine tumor cell lines were insensitive to direct mIFNα treatment, indicating a reliance on immune-mediated antitumor activity when tested in vivo. Immunoprofiling analyses post-administration with single-agent mCD38-mATT indicated increased prevalence and activation of NK cells in peripheral blood and increased intratumoral CD8+ T: Treg and CD8+ T: CD4+ T cell ratios, compared to anti-mCD38 antibody or murine IFNα alone. Follow-on experiments evaluating single-agent mCD38-mATT indicated modest activity on tumor growth in vivo. Combination administration of mCD38-mATT with SOC agents had increased anti-tumor activity compared to either single-agent administration alone. Conclusion: Administration of mCD38-mATT induced broad immunomodulation and antitumor responses, alone and in combination with SOC agents in immunocompetent mouse models, highlighting the impact of this agent on CD38+ cells, both tumor and immune. These results support further investigation of combination therapies in the ongoing clinical evaluation of TAK-573 in a Phase 1 trial in patients with relapsed refractory MM. Citation Format: Tomoya Hara, Christina Wong, Jie Yu, Sabrina Collins, Haiqing Wang, Hiroshi Sugimoto, Hong Zhang, Pia Bjorck, Michael D. Curley. A murine reactive version of TAK-573 (anti-CD38 attenuated IFNα fusion protein) shows immunomodulatory and antitumor activity, alone and in combination with standard-of-care agents, in IFNa-insensitive, immunocompetent murine multiple myeloma tumor models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5546.

Background:

Background: TAK-573 is a first-in-class, humanized, anti-CD38, IgG4 monoclonal antibody genetically fused to 2 attenuated interferon alpha-2b (IFNα2b) molecules. The specificity for CD38 and reduced binding affinity of the attenuated IFNα molecules significantly reduces the potential for off-target toxicity. TAK-573 binds to a site on CD38 that is distinct from the binding sites of currently available therapeutic antibodies, and therefore does not compete for binding with daratumumab or isatuximab. Non-clinical studies have shown that TAK-573 has robust anti-tumor activity, including complete responses, in MM xenograft models. Patients and Methods: The first in human phase I trial (NCT03215030) enrolled patients (pts) with relapsed or refractory multiple myeloma (RRMM) after at least 3 previous lines of treatment. Pts received TAK-573 as a 1 to 4-hour IV infusion in 11 dose levels from 0.001 to 3 mg/kg. The initial schedule was weekly for 8 doses, then every 2 weeks for 8 doses, and then monthly. Subsequent cohorts are also exploring dosing once every 2 (Q2), every 3 (Q3) or every 4 weeks (Q4). Peripheral blood (PB) and bone marrow (BM) aspirates were collected before and after TAK-573 dosing. CD38 receptor occupancy (RO) and receptor density (RD) were determined using 9-color flow cytometry. Serum samples were analyzed using the Immuno-Oncology panel of Olink's proximity extension assay platform to measure changes in cytokine and chemokine levels. Whole transcriptome sequencing of bulk RNA was performed to determine the type I interferon (IFN) gene signature induction. Mass cytometry-based immunophenotyping was utilized to characterize changes in immune cell prevalence and activation status of cryopreserved cells from both the PB and BM. Results: As of June 2020, 59 patients had been treated on all schedules. The median number of prior lines of therapy was 7 (range: 3-20); 93% had received at least 1 daratumumab-containing regimen, and 14% had received previous CAR-T cell therapy. Thrombocytopenia was the most frequent TEAE (83%) and was Grade ≥3 in 28 (47%) pts. Prolonged thrombocytopenia was a dose limiting toxicity (DLT) in 7 pts, but was not associated with clinical bleeding, and 9 pts required platelet transfusions. Neutropenia was reported as a TEAE in 54% of pts (Grade ≥3 in 49% pts), and was a DLT in 4 patients, including one pt who had febrile neutropenia. The maximum tolerated dose for the initial schedule was 0.1 mg/kg, and evaluation of other schedules is ongoing. Myeloma responses have been observed starting at doses of 0.1 mg/kg on the initial schedule, 0.4 mg/kg q2 weeks, and 1.5 mg/kg q4 weeks (as shown in Table 1). Single administration of TAK-573 resulted in a dose dependent increase in CD38 RO of PB-derived immune cells, with saturation of CD38 RO 4 hours after the end of infusion (EOI) at doses ≥ 0.2 mg/kg. The duration of saturation was dose dependent, with doses ≥ 0.75 mg/kg TAK-573 saturating CD38 RO through 24 hours. CD38 RO in BM samples showed similar results, with added variability due to the timing of sample collection and individual patients' tumor burden. At all dose levels, TAK-573 administration resulted in increases in the type I IFN gene signature 24 hours after the dose. As CD38 is an IFN-stimulated gene, TAK-573 treatment resulted in CD38 RD increases, most notably on NK cells but also on other CD38 positive cells, including MM cells within the BM. BM MM cells also showed decreases in complement-inhibitory proteins CD55 and CD59 after TAK-573 treatment. Circulating levels of IFN-associated chemokines (IFNγ, CXCL10, MCP-1 and IL-15) also increased, with maximal induction 4 hours after EOI. CD69 expression, a marker of early activation, increased on BM CD8+ T cells in 7 of 9 patients analyzed; the CD8+ T-cells for 3 of those 7 patients also showed increases in IFNγ positivity, indicating that TAK-573 treatment can increase the cytolytic potential of CD8+ T-cells in the BM of a subset of patients. Conclusion: TAK-573 is a clinically and pharmacologically active molecule that mediates IFNAR pathway modulation and leads to myeloma responses. Additional biomarker data is being collected to further refine the MOA, which will inform the recommended phase 2 dose, optimal schedule of administration, and rational development of TAK-573. Disclosures Vogl: Active Biotech: Consultancy, Research Funding; Takeda: Consultancy; Karyopharm: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Oncopeptides: Consultancy; MorphoSys: Consultancy. Kaufman:Takeda: Consultancy, Honoraria; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Sanofi/Genyzme: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Tecnopharma: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; AbbVie: Consultancy. Holstein:GSK: Consultancy; Celgene: Consultancy; Sorrento: Consultancy; Sanofi: Consultancy; Oncopeptides: Consultancy, Research Funding; Takeda: Consultancy; Adaptive Biotechnologies: Consultancy; Genentech: Consultancy. Nadeem:Takeda: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees. Suryanarayan:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Collins:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Parot:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Chaudhry:Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: TAK-573 is a first-in-class, humanized, anti-CD38, IgG4 monoclonal antibody genetically fused to 2 attenuated interferon alpha-2b (IFNα2b) molecules

Background TAK-573, a humanized, anti-CD38, IgG4, monoclonal antibody genetically fused to two attenuated IFNα2b molecules, was designed for targeted delivery of attenuated IFNα2b to CD38 expressing (CD38+) cells, utilizing a unique epitope of CD38 that does not compete with current anti-CD38 therapies. Preclinical evaluation of TAK-573 confirmed activation of type I IFN signaling in CD38+ cells inducing direct anti-proliferative effects on multiple myeloma (MM) cells and direct and indirect immune cell activation. Here we provide the preliminary analyses of the pharmacodynamic data currently available from the ongoing Ph I/II TAK-573-1501 clinical study in patients with relapsed/refractory MM (NCT03215030). Methods Peripheral blood (PB) and bone marrow (BM) aspirates were collected from patients at pre- and post-dose time points for exploratory biomarker analyses. CD38 receptor occupancy (RO) and receptor density (RD) were determined using a 9-color flow cytometry assay. Whole transcriptome sequencing of bulk RNA was performed and analyzed to assess the type I IFN gene signature. Serum samples were analyzed using Olink’s Proximity Extension Assay Immuno-Oncology panel to measure changes in cytokine levels. Mass cytometry-based immunophenotyping was utilized to characterize changes in immune cell prevalence and activation status of cryopreserved cells. Results Administration of TAK-573 resulted in a dose dependent increase in CD38 RO of PB-derived immune cells with saturation detected 4 hours after the end of infusion (EOI) at doses ≥ 0.2 mg/kg. The duration of saturation was dose dependent with doses ≥ 0.75 mg/kg saturating CD38 RO through 24 hours. All dose levels tested resulted in increases in the type I IFN gene signature at 24 hours. Consistent with CD38 being an IFN stimulated gene, TAK-573 treatment resulted in CD38 RD increases most notably on NK cells, but also on other CD38+ cells including MM cells. Circulating levels of IFN-associated cytokines were also elevated, with maximal induction 4 hours after the EOI. CD8+ T-cells in BM showed increased CD69 expression in 7 of 9 patients analyzed, 3 of whom also showed increases in both IFNγ and granzyme B positivity suggesting TAK-573 treatment results in increased BM cytolytic CD8+ T-cells, in a subset of patients. Conclusions These preliminary biomarker data indicate that TAK-573 is a pharmacologically active molecule that mediates its effect through IFNAR pathway modulation. Additional data are being collected to further refine the mechanism of action (Image 1), which will inform the recommended phase 2 dose and optimal schedule of administration for the development of TAK-573. Trial Registration ClinicalTrials. gov: NCT03215030 Ethics Approval The TAK-573-1501 study is approved by WIRB-Copernicus Group, University of Nebraska Medical Center, Dana Farber Cancer Institute and Advarra IRBs.

There are limited data on the genomic landscape of Small Cell Lung Cancer (SCLC), often limited by access to large biopsies. We sought to characterize the molecular profile of patients with relapsed and refractory SCLC (R/R SCLC) using circulating tumor cell (CTC) DNA and cell free DNA (cfDNA). Blood samples (7.5 ml for CTC enumeration and 10 ml for cfDNA isolation) were prospectively collected from patients with R/R SCLC at the time of documented progression. CTC were enumerated using CellSearch®. Next generation DNA sequencing (NGS) was carried out on CTC DNA, cfDNA and matched archived tumor biopsies using two panels, i. Personal genome diagnostic panel; (PGDx PlasmaSelectTM) with 63 genes, and ii. Custom panel with 90 genes. Twelve patients with R/R SCLC were enrolled (3 male, median age 63 years, 2 limited stage at diagnosis, 33% platinum-refractory). There was no association of CTC count with survival or disease stage at diagnosis. A positive association was seen between CTC count and quantity of cfDNA (Pearson’s correlation=0.77, p=0.0091). Multiple genetic alterations were identified from CTC DNA and cfDNA, including mutations in p53, Rb and gene amplification of the c-Myc, which are the most frequent genetic alterations reported in SCLC. Using PGDx PlasmaSelectTM panel, genetic alterations were identified in 11/12 patients from cfDNA and 9/12 patients from CTC DNA. Mutations in DNMT3A, AR, KIT, ATM and PIK3CA each were seen in ≥ 3 patients. Additional somatic mutations including APC, NOTCH3, SYNE 1, CREBBP, ATRX were identified using the custom panel, in 9/12 from cfDNA and 8/12 from CTC DNA. The most common mutation across all samples was p53 (n=10/11). Identical genetic mutations were identified in both CTC DNA and cfDNA from the same patients. Matched liquid and tumor biopsies were available for 6/12 patients. With the exception of p53, limited concordance was found between NGS from liquid and tumor biopsies. Concordance rate was noted to be higher for mutated genes in tissue samples with higher allelic frequency (AF>= 1%, concordance rate ∼ 10%, AF>= 20%, concordance rate ∼ 29%). Data from this pilot study demonstrate that it is feasible to use cfDNA and CTC for characterization of known genetic alterations in SCLC patients. Larger studies are needed to define its use in the clinical setting. Such approaches may ultimately prove useful in identifying prognostic, predictive and resistance biomarkers.

Abstract Background Spleen tyrosine kinase (SYK) is a nonreceptor cytoplasmic protein kinase and a key mediator of immunoreceptor signaling that has been shown to play an important role in the pathogenesis of both B-cell and myeloid malignancies. SYK has also been shown to directly bind and activate FMS-like tyrosine kinase 3 (FLT-3), a Class III receptor tyrosine kinase that is commonly mutated in approximately 30% of pts with AML (Puissant et al. Cancer Cell 2014;25:226-42). TAK-659 is an investigational, reversible, and potent dual inhibitor of SYK and FLT-3. Preclinical studies with TAK-659 have demonstrated growth inhibition of cell lines and xenograft tumor models of B-cell lymphoma or AML origin. Moreover, TAK-659 has exhibited antitumor activity in lymphoma pts in an ongoing clinical trial (Petrich et al. Blood 2015;126:2693). The primary objectives of the phase 1b dose-finding portion of this study are to evaluate the safety, tolerability, and maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D) of TAK-659, as well as preliminary efficacy in the phase 2 expansion study. Secondary objectives include evaluation of TAK-659 pharmacokinetics (PK) in this pt population. Methods During dose escalation using a 3x3 schema, adult pts with R/R AML received oral TAK-659 daily (QD) in 28-d cycles (C) starting with a dose of 60 mg. Adverse events (AEs) were assessed per NCI-CTCAE v4.03. Response per IWG criteria for AML was assessed between d22 and d28 of C1, C2, and C4. Blood samples for plasma pharmacokinetic (PK) assessments were collected pre-dose and at multiple times post-dose on d1 and d15 of C1. The pharmacodynamic effect of TAK-659 was assessed at multiple time points by measuring the phosphorylation of ribosomal protein S6 (pS6) in peripheral AML blasts using flow cytometry. FLT-3 mutation status (wild type [FLT-3-WT], FLT-3-ITD, or point mutation [FLT-3-D835Y]) was assessed using a PCR-based assay at a central laboratory. The effect of TAK-659 treatment on FLT-3-ITD phosphorylation was evaluated using a plasma inhibitory assay (PIA) as previously described (Levis et al. Blood 2006;108:3477-83). Results At data cut-off (June 9, 2016), 15 pts had been enrolled at TAK-659 QD 60 mg (n=4), 100 mg (n=7), or 120 mg (n=4). No dose-limiting toxicity per protocol has been observed. Dose escalation is currently ongoing at 160 mg QD. In the safety population (n=13), median age was 67 yrs (range 25-86), 69% of pts were male, and 38% had received ≥4 prior lines of therapy. Baseline mutation data was available for 12 pts: 6 pts were FLT-3-WT, 3 pts had FLT-3-ITD, 1 pt had FLT-3-D835Y, and 2 pts had concurrent FLT-3-ITD/D835Y mutations. In the safety population, all-grade drug-related AEs occurred in 12 (92%) pts overall; the most common were elevated AST (31%), ALT (23%), and amylase levels (23%). Grade ≥3 drug-related AEs occurred in 7 (54%) pts including: increased ALT, AST, and amylase levels, cataract, positive fungal test, macular fibrosis, pancreatitis, pneumocystis jirovecii pneumonia, rash, and fungal sinusitis (each 1pt). Blood LDH levels were increased in almost all pts (significance unknown). Three pts discontinued TAK-659 due to AEs and 3 pts died on study; none of these events were considered related to the study drug. Preliminary plasma PK of TAK-659 (n=11, 60-100 mg) was characterized by rapid absorption (median Tmax of 2 hours), moderate variability in steady-state exposures (42% coefficient of variation for C1 d15 dose-normalized AUCtau), and mean accumulation of 2.1-fold after repeated QD dosing for 15 days. Of 9 pts evaluated to date, pS6 was detected at baseline and reduced after dosing in 4 pts (2 FLT-3-ITD; 2 FLT-3-WT). At 60 mg and 100 mg TAK-659, up to 70% inhibition of FLT-3-ITD phosphorylation was observed as assessed by PIA. Early signs of clinical activity were observed, with decreases in peripheral blood myeloblasts observed in some pts. Assessment is ongoing and preliminary efficacy data will be presented. Conclusions TAK-659 has a unique mechanism of action with dual inhibition of SYK and FLT-3. Dose escalation to determine the MTD/RP2D is ongoing. TAK-659 exhibits an acceptable PK profile in R/R AML pts, supporting continuous oral QD dosing. Disclosures Kaplan: Seattle Genetics: Research Funding; Janssen: Research Funding. Morris:Boehringer-Ingelheim: Speakers Bureau. Altman:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Syros: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Wise-Draper:Merck: Research Funding. Collins:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Kannan:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Wang:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Faucette:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Lee:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Shou:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Levis:Millennium: Consultancy, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Daiichi-Sankyo: Consultancy, Honoraria.