Minimum Anticipated Biological Effect Level Research Articles

Dosing Strategies and Quantitative Clinical Pharmacology for Bispecific T-Cell Engagers Development in Oncology.

Bispecific T-cell Engagers (TCEs) are promising anti-cancer treatments that bind to both the CD3 receptors on T cells and an antigen on the surface of tumor cells, creating an immune synapse, leading to killing of malignant tumor cells. These novel therapies have unique development challenges, with specific safety risks of cytokine release syndrome. These on-target adverse events fortunately can be mitigated and deconvoluted from efficacy via innovative dosing strategies, making clinical pharmacology key in the development of these therapies. This review assesses dose selection and the role of quantitative clinical pharmacology in the development of the first eight approved TCEs. Model informed drug development (MIDD) strategies can be used at every stage to guide TCE development. Mechanistic modeling approaches allow for (1) efficacious yet safe first-in-human dose selection as compared with in vitro minimum anticipated biological effect level (MABEL) approach; (2) rapid escalation and reducing number of patients with subtherapeutic doses through model-based adaptive design; (3) virtual testing of different step-up dosing regimens that may not be feasible to be evaluated in the clinic; and (4) selection and justification of the optimal clinical step-up and full treatment doses. As the knowledge base around TCEs continues to grow, the relevance and utilization of MIDD strategies for supporting the development and dose optimization of these molecules are expected to advance, optimizing the benefit-risk profile for cancer patients.

Translational PK/PD and the first-in-human dose selection of a PD1/IL15: an engineered recombinant targeted cytokine for cancer immunotherapy.

Interleukin 15 (IL-15) is a potential anticancer agent and numerous engineered IL-15 agonists are currently under clinical investigation. Selective targeting of IL-15 to specific lymphocytes may enhance therapeutic effects while helping to minimize toxicities. We designed and built a heterodimeric targeted cytokine (TaCk) that consists of an anti-programmed cell death 1 receptor antibody (anti-PD-1) and an engineered IL-15. This "PD1/IL15" selectively delivers IL-15 signaling to lymphocytes expressing PD-1. We then investigated the pharmacokinetic (PK) and pharmacodynamic (PD) effects of PD1/IL15 TaCk on immune cell subsets in cynomolgus monkeys after single and repeat intravenous dose administrations. We used these results to determine the first-in-human (FIH) dose and dosing frequency for early clinical trials. The PD1/IL15 TaCk exhibited a nonlinear multiphasic PK profile, while the untargeted isotype control TaCk, containing an anti-respiratory syncytial virus antibody (RSV/IL15), showed linear and dose proportional PK. The PD1/IL15 TaCk also displayed a considerably prolonged PK (half-life range ∼1.0-4.1 days) compared to wild-type IL-15 (half-life ∼1.1h), which led to an enhanced cell expansion PD response. The PD was dose-dependent, durable, and selective for PD-1+ lymphocytes. Notably, the dose- and time-dependent PK was attributed to dynamic TMDD resulting from test article-induced lymphocyte expansion upon repeat administration. The recommended first-in-human (FIH) dose of PD1/IL15 TaCk is 0.003mg/kg, determined based on a minimum anticipated biological effect level (MABEL) approach utilizing a combination of in vitro and preclinical in vivo data. This work provides insight into the complex PK/PD relationship of PD1/IL15 TaCk in monkeys and informs the recommended starting dose and dosing frequency selection to support clinical evaluation of this novel targeted cytokine.

Dose Escalation of HLA-A2-WT1 CD3 T-Cell Bispecific Antibody in a Phase I Study in Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML)

Background: RO7283420 (RG6007) is a 2+1 TCR-like (TCR-L) T-cell bispecific (TCB) antibody targeting CD3 and the RMFPNAPYL peptide of Wilms Tumor 1 (WT1) protein presented by the major histocompatibility complex-I HLA-A*02 on acute myeloid leukemia (AML) blasts and other antigen presenting cells. The pre-clinical evaluation of RO7283420 in our in vivo humanized AML xenografts and ex vivo AML co-culture models showed strong T-cell mediated AML cell killing (Augsberger C, et al. Blood 2021). A Phase 1 dose-escalation (DE) study (NCT04580121) evaluated the safety, tolerability, pharmacokinetics, anti-drug antibodies (ADAs), and anti-leukemic activity of RO7283420 in patients with relapsed/refractory (R/R) AML. Methods: In this open-label, multi-center study, DE was performed using a 3+3 design. Patients received RO7283420 every 3 weeks (Q3W, n=46), or every week (QW, n=4) as intravenous (IV) infusions. Preliminary anti-leukemic activity included response assessment according to European Leukemia Net (ELN) response categories (adapted from Döhner H, et al. Blood 2017). Results: As of 13 April 2023, 50 HLA-A2+ R/R AML patients received at least one dose of RO7283420. Patients had a median age of 65.5 years (range 35-84), presented with ECOG of 0 (56%) or 1 (38%) or 2 (6%), and 58% were male. Median prior line of therapy was 2 (range 1-5). Overall, 58% of patients had relapsed and 42% had primary refractory disease. According to the ELN 2017 risk stratification, patients were of adverse (48%), intermediate (38%) or favorable (8%) risk category, for 6% of patients the risk category missing. The most common genetic abnormalities reported were RUNX1 (21%), ASXL1 (17%), TP53 (10.6%), FLT3-ITD (6.4%) and NPM1 (6.4%) of the 47 patients tested. Median bone marrow blast percentage at baseline was 35% (range 3-90%), while the median of circulating blast was 17% (range 0-88%). Study patients received RO7283420 IV at 13 different dose levels, ranging from a Minimum Anticipated Biological Effect Level (MABEL) of 0.15 mg (flat) to 18 mg Q3W (with a preceding weekly 1/3 mg ‘double step-up’ during Cycle 1) and one QW dose level with 9 mg preceded by a 1/3 mg step-up. Maximum tolerated dose was reached at 1/3/12 mg double step-up Q3W. Explored alternative QW schedule was not tolerable at 1/3/9 mg. The most common (≥20%) adverse events (AEs) were cytokine release syndrome (CRS) occurring in 34 (68%), pneumonia 14 (28%), pyrexia 13 (26%), febrile neutropenia 13 (26%), hyperglycemia 12 (24%), hypokalemia 11 (22%), and nausea 10 (20%) of patients. Eight dose limiting toxicities (DLTs) were reported: five G3 CRS (at 1/3, 2/12, 1/6/12 mg dose levels), G3 stomatitis (at 1/3/12 mg), G3 myositis (at 1/3/18 mg), and G4 thrombocytopenia (at 1/3/18 mg). Eleven patients (22%) experienced Grade 5 AEs with pneumonia, sepsis, and hemophagocytic lymphohistiocytosis (HLH) reported in >1 patient; all Grade 5 events were considered unrelated to RO728342 except 1 (at 1/3/9 mg) of 2 HLH events. IV PK has been overall dose-linear and characterized by a terminal half-life of 29 to 84 hours and a clearance of 58 to 92 mL/h. Preliminary ADA incidence within the study population was 19%. In the dose ranges tested, a trend for study drug exposure-dependent blast reduction was observed in blood, while a clear exposure-response relationship could not be established with BM blast reduction. Furthermore, our preliminary pharmacodynamic analysis identified expansion of naive and memory CD8 T cells in blood and activated CD8+ T cells in bone marrow, in line with the expected mode of action (MoA) of RO7283420. Preliminary efficacy signals were observed with 3 complete responses (CR), including 1 CR with incomplete blood count recovery. Conclusions: RO7283420 is the first TCR-L TCB antibody evaluated in AML. We observed pharmacodynamic evidence of T-cell activation and expansion in the clinic, in line with the expected MoA of TCBs, however, at the explored doses, no clear exposure-response relationship and only a modest clinical activity were observed. The safety profile was shown to be consistent with the other TCBs and R/R AML population. Based on the totality of data, the study was discontinued.

Phase 1A, first-in-human study of ARB202, bispecific antibody to CDH17 and CD3, in advanced gastrointestinal malignancies expressing CDH17.

25 Background: Cadherin-17 (CDH17) is a highly specific therapeutic cancer target, of which aberrant expression has been reported in 50-95% in GI tumor samples (including stomach, pancreas, liver/bile duct, rectum, and colon). Normal CDH17 expression is primarily in the water-tight junction between mucosal epithelial cells which is potentially “masked” from the immune system (Feng, Z., et al., Nat Cancer, 2022). A bispecific T-cell engager ARB202 using CD3 to aid the formation of an immunological synapse CDH17 tumor cells and T-cells is being studied. Methods: In an ongoing dose-escalation phase IA part of a continuous study, patients with advanced CD17+ solid tumors are being given up to 3 doses of ARB202 bispecific. In part 1, 28 pts can be treated at dose levels from 0.0003 mg/kg to 10 mg/kg; Based on clinical response intra-dosing of tolerated (higher) doses can occur in for the 2nd and 3rd doses. Second and 3 doses are planned at the 4th cohort starting at a dose of 0.010 mg/kg when tissue levels are likely physiologically active. Minimum anticipated biological effect level (MABEL) dosing which is based on the most sensitive in vitro assay is being used to set the initial 3 doses to ensure safety of any T-cell engagement at low levels in circulation. Data cutoff 10.04.23. Results: Colorectal, gastric, pancreatic and cholangiocarcinoma patients have screened positive for CDH17 by semi-automated tissue immunostaining. Seven patients have completed dosing in the first 3 cohorts and have shown tolerability to 0.0003 to 0.003 mg/kg single IV doses. The Cmax measured within 1 hour of dosing has confirmed the circulating PK range of 10-20 ng/ml for the 2nd cohort and 40-50 ng/ml in the 3rd cohort consistent with the expected PK of antibody-like volume of distribution. The safety review committee has approved the dose escalation to proceed to the 4th cohort Identifier: NCT05411133. Conclusions: ARB202 a bispecific T-cell engager has shown tolerability up to 40ng/ml Cmax in circulation suggesting no clinically significant CD3 only binding cell activation at these levels. These data allow for higher dosing to achieve tissue ARB202 concentrations where anti-CDH17/CD3 aided synapse formation between tissue tumor cells and T-cells can lead to clinical evidence of bispecific target engagement and their expected effects. Clinical trial information: NCT05411133 .

Abstract CT209: A first-in-human phase 1 trial of IO-108, an antagonist antibody targeting LILRB2 (ILT4), as monotherapy and in combination with pembrolizumab in adult patients with advanced relapsed or refractory solid tumors (NCT05054348)

Abstract Cancer immunotherapy has entered the mainstream with approval of T-cell checkpoint inhibitors. However, most patients with advanced solid tumors do not derive benefits, or relapse after T-cell checkpoint blockade. Myeloid checkpoint inhibition is a new approach to cancer immunotherapy. LILRB2 is primarily expressed by myeloid cells and its expression in tumors is associated with high macrophage infiltration. Several LILRB2 ligands (HLA-G, ANGPTL2, and SEMA4A) are known to contribute to the immune suppressive microenvironment of solid tumors. Blockade of the LILRB2 pathway has the potential to reactivate or enhance anti-tumor T cell immune responses. IO-108 is a IgG4 monoclonal antibody that specifically binds LILRB2 to block ligands interaction and activation of LILRB2. In vitro, IO-108 treatment of primary immune cells results increased pro-inflammatory responses and an enhanced antigen presenting cell phenotypes. A Good Laboratory Practice repeat-dose, 15-day toxicology study in Cynomolgus monkeys at 0 (control), 1, 10, or 100 mg/kg/dose administered intravenously once weekly for a total of 3 doses showed that IO-108 was well-tolerated at all dose levels, with only non-statistically significant reduction of thyroid glands weight. No-observed-adverse-effect-level (NOAEL) of 100 mg/kg provides a sufficient safety margin for the IO-108 starting dose of 60 mg, which was derived using a MABEL (minimum anticipated biological effect level) approach. This clinical trial is a first-in-human, Phase 1, multicenter, open-label, dose-escalation, safety, pharmacokinetic (PK), and pharmacodynamic evaluation of intravenously administered IO-108, both as monotherapy and in combination with pembrolizumab, in adult patients with solid tumors that have failed standard of care therapies (NCT05054348). It is estimated that up to 36 patients will be enrolled in the study. IO-108 will be administered every 21 days, with a dose-limiting toxicity (DLT) evaluation period of 21 days. Patients will be enrolled into sequential cohorts and treated with increasing doses of IO-108 using mTPI (modified Toxicity Probability Interval) method. Safety, PK, and clinical activity will be evaluated on an ongoing basis. The primary objective of the study is to assess safety and tolerability at increasing dose levels of IO-108 in successive cohorts of adult patients (treated with or without with pembrolizumab) with advanced relapsed or refractory solid tumors, to estimate the maximal tolerated dose (MTD) or maximum administered dose (MAD) and select the recommended phase 2 dose (RP2D). Secondary objectives include characterizing PK, immunogenicity, and preliminary anti-tumor activity. Biomarker evaluation will include changes in myeloid cell markers and T-cells, LILRB2 expression level and receptor occupancy. Statistical analyses will be primarily descriptive in nature. Tabulations will be produced for appropriate disposition, demographic, baseline disease characteristics, safety, PK, pharmacodynamic, and clinical activity parameters. Response to treatment as assessed by RECIST v1.1 will be tabulated. To date, five patients have been dosed without DLT. Citation Format: John Powderly, Manish Patel, Paul Woodard, Luke Chung, Hongyu Tian, Elizabeth Wieland, Kyu Hong, Maria Jose Costa, X. Charlene Liao, Matthew Taylor. A first-in-human phase 1 trial of IO-108, an antagonist antibody targeting LILRB2 (ILT4), as monotherapy and in combination with pembrolizumab in adult patients with advanced relapsed or refractory solid tumors (NCT05054348) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT209.

Abstract 5318: Humanized STC10 is a monoclonal antibody to BTN1A1, a novel immunotherapeutic target to be evaluated in a planned phase 1 study

Abstract Butyrophilin 1A1 (BTN1A1) is a novel immune checkpoint protein that exhibits an expression pattern mutually exclusive to that of PD-1/PD-L1 and may represent a promising therapeutic target for tumors that are anti-PD-1/PD-L1 antibody refractory. BTN1A1 was identified as a potential stress-inducible candidate immune checkpoint using the STCube in vivo immune target discovery platform. Additional analyses revealed that BTN1A1 was highly expressed in multiple human tumor types including urothelial carcinoma and NSCLC, with no overlap between BTN1A1 and PD-1/PDL-1 expression patterns. Mouse studies demonstrated that an anti-BTN1A1 antibody exhibited antitumor activity both as a single agent and in combination with anti-PD-1/PD-L1 or radiation therapy. A humanized anti-BTN1A1 antibody, hSTC810, was developed and found to suppress tumor growth in A549 CDX humanized murine models. Further studies identified Galectin 9 (Gal9) as a BTN1A1 receptor that can form a three protein complex with BTN1A1 and PD-1, thereby suppressing T cell receptor signaling and T cell activation. As high Gal9 expression levels are correlated with poor prognosis in multiple cancers, our results highlight this BTN1A1-Gal9-PD-1 axis as a novel therapeutic target for immunotherapeutic drug development. Given these findings, a first in human study of hSTC810 is in development to evaluate the safety profile of this therapy and to identify a dose for its further evaluation as an anticancer therapy. PK modeling including allometric scaling was performed to conduct simulations to predict the PK profile of hSTC810 after IV administration in humans and to identify possible doses needed to achieve tumor concentrations corresponding to the minimum anticipated biological effect level (MABEL) of 20% receptor occupancy (RO), 80% RO, or 95% RO. The partition coefficient was used to predict concentrations at the tumor site based on predicted serum concentrations. Simulations were performed for 100 subjects after the administration of multiple Q2W doses. The dose of 0.1 mg/kg was predicted to have <20% RO, 0.3 mg/kg to have ~21-35% RO, 1 mg/kg to have ~47-65% RO and 15 mg/kg to have ~93-96% RO at steady state. We anticipate beginning study enrollment in the first quarter of 2022 at sites in the United States sand South Korea. The study is a standard 3+3 dose-escalation with a dose of 0.3 mg/kg for a single patient followed by a starting dose of 1 mg/kg. Citation Format: Lynn Jackson Howie, Ezra M. Chung, Young-Seung Kim, Yujin Jung, Hyunjin Jung, Stephen Yoo. Humanized STC10 is a monoclonal antibody to BTN1A1, a novel immunotherapeutic target to be evaluated in a planned phase 1 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5318.

IND-Enabling Studies of a Switchable Chimeric Antigen Receptor-T Cell (CLBR001+SWI019) to Support First in Human Clinical Study

Despite the tremendous clinical benefits, adverse events associated with CAR-T cell therapy remain a challenge. Most frequent adverse events are cytokine release and immune effector cell-associated neurotoxicity syndromes due to the inability to modulate the level of activity of current CAR-T cell products after administration to patients. Additional challenges include on target, off tumor toxicities and antigen loss mediated relapse of disease.To address these challenges, we have developed a “switchable” CAR-T (sCAR-T) where the activity of the sCAR-T cells is controlled by an antibody-based switch. The switch targets the tumor antigen, and the sCAR recognizes a unique peptide engrafted on the switch. The switch creates a bridge between the sCAR-T cell and the tumor cell, activating the sCAR-T cells and inducing tumor cell killing. Combined, the switch and sCAR-T cells afford complete elimination of tumors in xenograft and syngeneic models, but individually, each is designed to be inactive. A short half-life of the switch allows for a rapid modulation of sCART-cell activity through the switch dosing. Moreover, by swapping different switches, sCAR-T cells can be modularly redirected against other tumor targets. Further, we have shown the cyclical on/off stimulation of the sCAR-T cells affords improved memory and persistence of the sCAR-T cells. Here, we report IND-enabling studies for an optimized CD19-targeted switch (SWI019) and sCAR-T cell (CLBR001) to support a first in human (FIH) clinical study of the combination.The preclinical development of a platform which includes a sCAR-T cell that lacks any endogenous antigen target, in combination with an antibody-based switch molecule that lacks intrinsic activity in the absence of the sCAR-T cell, necessitated development of novel approaches. Fidelity of such a system is essential to control, thus, to confirm CLBR001 cells did not activate in the presence of normal tissues, in vitro activity studies were performed by co-culturing CLBR001 cells, in the presence or absence of SWI019, and a panel of 14 primary cells. This panel represented a survey of vital tissues throughout the body. CLBR001 did not demonstrate activity in any of the 14 cell types tested, supporting a high fidelity of CLBR001 recognition for SWI019.Because SWI019 lacks activity in the absence of CLBR001 cells, traditional toxicology studies to identify the no adverse effect level (NOAEL) in support of the first in human starting dose were not applicable. In such cases, a minimal anticipated biological effect level (MABEL) is commonly used to support starting human dose based on the predicted Cmax; however, the femtomolar-level in vitro activity of SWI019 in combination with CLBR001 resulted in starting doses that were modeled to be far outside of the range of potential clinical activity. Therefore, an in vivo-based approach to determine MABEL was developed. CLBR001 cells were administered in NSG mice bearing CD19+ Nalm-6 cell tumors and a single dose titration of SWI019 was performed. Comparison of the SWI019 efficacious dose (ED 50) values for anti-tumor activity, peripheral cytokines, and CLBR001 cells in peripheral blood demonstrated that reduction in Nalm-6 tumor burden was the most sensitive marker of activity. Extravasation of CLBR001 cells from peripheral blood and all three cytokines (IFN-γ, IL-2, and TNF-α) exhibited weaker ED 50 values. Therefore, antitumor activity (Nalm-6 tumor burden reduction) was chosen as the parameter for which to determine in vivo MABEL. Allometric scaling, using mouse and NHP SWI019 PK data, was used to model a SWI019 recommended dose in humans corresponding to the ED 20 of the in vivo MABEL study. Compared to the dose modelled using the in vitro MABEL approach, the in vivo MABEL approach afforded a first in human starting point which was ~13000-fold higher. We expect this approach provides an excellent starting point for the first in human study which balances safety and the potential for patient benefit.In summary, the results presented in this abstract led to the initiation of clinical trial NCT04450069, the combination of CLBR001+SWI019 for the treatment of relapse/ refractory B cell malignancies. DisclosuresStone: Abbvie: Current Employment, Current equity holder in publicly-traded company. Trikha: Abbvie: Current Employment, Current equity holder in publicly-traded company. Young: Abbvie: Research Funding; Qihan Bio: Membership on an entity's Board of Directors or advisory committees; Shoreline Bio: Membership on an entity's Board of Directors or advisory committees.

Tolerability and Single Agent Anti-Neoplastic Activity of the CD3xCD123 Bispecific Antibody APVO436 in Patients with Relapsed/Refractory AML or MDS

Tolerability and Single Agent Anti-Neoplastic Activity of the CD3xCD123 Bispecific Antibody APVO436 in Patients with Relapsed/Refractory AML or MDS

A Clinical Phase 1B Study of the CD3xCD123 Bispecific Antibody APVO436 in Patients with Relapsed/Refractory Acute Myeloid Leukemia or Myelodysplastic Syndrome.

Simple SummaryAML is a common form of blood cancer in adults. This study was undertaken to evaluate if AML patients who have failed the available standard treatment options could tolerate and potentially benefit from a new form of therapy. This new therapy activates patients’ own immune system against AML cells. The findings from this research may provide the foundation for a potentially more effective future form of standard therapy that is less likely to fail.APVO436 is a recombinant T cell-engaging humanized bispecific antibody designed to redirect host T cell cytotoxicity in an MHC-independent manner to CD123-expressing blast cells from patients with hematologic malignancies and has exhibited single-agent anti-leukemia activity in murine xenograft models of acute myeloid leukemia (AML). In this first-in-human (FIH) multicenter phase 1B study, we sought to determine the safety and tolerability of APVO436 in R/R AML/myelodysplastic syndrome (MDS) patients and identify a clinically active recommended phase 2 dose (RP2D) level for its further clinical development. A total of 46 R/R AML/MDS patients who had failed 1–8 prior lines of therapy received APVO436 as weekly intravenous (IV) infusions at 10 different dose levels, ranging from a Minimum Anticipated Biological Effect Level (MABEL) of 0.3 mcg to 60 mcg. APVO436 exhibited a favorable safety profile with acceptable tolerability and manageable drug-related adverse events (AEs), and its maximum tolerated dose (MTD) was not reached at a weekly dose of 60 mcg. The most common APVO436-related AEs were infusion-related reactions (IRR) occurring in 13 (28.3%) patients and cytokine release syndrome (CRS) occurring in 10 (21.7%). The single dose RP2D level was identified as 0.2 mcg/kg. Preliminary efficacy signals were observed in both AML and MDS patients: Prolonged stable disease (SD), partial remissions (PR), and complete remissions (CR) were observed in R/R AML patients as best overall responses to APVO436 at the RP2D level. Three of six evaluable MDS patients had marrow CRs. The safety and preliminary evidence of efficacy of APVO436 in R/R AML and MDS patients warrant further investigation of its clinical impact potential.

Translational Approach of Using Ex Vivo Cytotoxicity and Early Clinical Data to Predict Teclistamab Efficacious Therapeutic Range in Multiple Myeloma Patients

B cell maturation antigen (BCMA; CD269; TNFRSF17) is a surface receptor, expressed on benign and malignant plasma cells. The restricted expression of BCMA on B-cell lineage makes it an ideal target for multiple myeloma (MM) immunotherapy. BCMAxCD3 bispecific antibody (Teclistamab; JNJ-64007957) has been developed to recruit CD3+ T-cells to BCMA+ MM cells. Teclistamab demonstrated potent cytotoxicity in a murine xenograft model and against ex vivo primary MM cells. Teclistamab clinical starting dose in the first in human (FIH) study in relapsed refractory MM patients began at the minimal anticipated biological effect level (MABEL) of 0.3 µg/kg using the EC20 of the in vitro cytotoxicity assay in the purified T cells model with MM.1R cell line. Since the MABEL dose is usually low, it is important to have guidance on the expected therapeutic range in patients. The therapeutic concentrations of teclistamab were estimated from an ex vivo cytotoxicity assay in which samples from MM patients (frozen purified mononuclear cells from bone marrow) were treated with healthy human purified T cells (1:1 ratio) spiked with teclistamab and incubated for 48 hours. The mean and range of EC50 and EC90 values of the cytotoxicity endpoint were estimated. The pharmacokinetic (PK) data following the first cycle doses in the low dose cohorts in the FIH study in MM patients were modeled using 2-compartment model and simulated to predict the doses that will have average and trough serum teclistamab concentrations in the expected therapeutic range (between EC50 and EC90). The predicted doses with average serum concentrations between the mean EC50 (372 ng/mL) and mean EC90 (2287 ng/mL) range were validated with the observed clinical data showing positive response in 2 out of 4 patients at the 38.4 µg/kg intravenous treatment dose level and their average serum teclistamab concentration overlaid within the estimated therapeutic range. This was also confirmed with the teclistamab concentrations in bone marrow samples (measured in a subset of MM patients in the study) where they were found to superimpose in the estimated therapeutic range. In addition, simulations predicted the dose that will have trough levels above the maximum EC90 (6070 ng/mL), to account for patients with high tumor burden, at which the observed clinical data have shown promising response rate and has been selected to be the recommended subcutaneous phase 2 dose of 1500 µg/kg. In conclusion, ex vivo cytotoxicity assay with MM patients bone marrow samples is an informative tool to predict the efficacious serum concentration of immuno-oncology drugs in MM patients. PK modeling and simulations of MM patients' data in FIH study coupled with the ex vivo cytotoxicity estimates provided guidance on the expected recommended phase 2 dose during the escalation phase of the FIH study. Disclosures Girgis: Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Wang Lin:Johnson & Johnson: Current Employment. Pillarisetti:Johnson & Johnson: Current Employment. Banerjee:Janssen: Current Employment. Goldberg:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Shetty:Johnson & Johnson: Current Employment. Stephenson:Johnson & Johnson: Current Employment, Current equity holder in private company. Hilder:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Hanna:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Smit:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Adams III:Genmab: Current Employment. Sun:Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Infante:Janssen: Current Employment. Elsayed:Johnson & Johnson: Current Employment. Sharma:Johnson & Johnson: Current Employment.

Abstract 2273: Selection of first-in-human clinical dose range for the tumor-targeted 4-1BB agonist MP0310 (AMG 506) using a pharmacokinetic/pharmacodynamics modeling approach

Abstract Following the clinical success of checkpoint inhibitors, cancer immunotherapy is rapidly expanding into combination treatments to enhance response rates and duration. Engagement of co-stimulatory molecules from the tumor necrosis factor receptor (TNFR) superfamily, including 4-1BB, may be a promising approach to enhance the benefits of cancer immunotherapy. Agonistic antibodies against the costimulatory receptor 4-1BB (CD137) have been shown to effectively enhance the anti-tumor activity of checkpoint inhibitors and other agents in preclinical animal models. However, the clinical development of 4-1BB agonistic antibodies has met with limited success thus far. Anti-4-1BB monoclonal antibodies have either been reported to cause significant dose-limiting hepatotoxicity or demonstrated limited efficacy as single agent therapeutics. We generated a DARPin® therapeutic candidate, MP0310 (AMG 506), which comprises domains binding to 4-1BB and fibroblast activation protein (FAP). MP0310 triggers 4-1BB activation only if bound and clustered via FAP which is abundantly expressed by cancer associated fibroblasts present in many solid tumors. In vitro functional assays indicate that MP0310 is a potent T cell co-stimulator in the presence of FAP-expressing cells. In vivo activity of tumor-targeted 4-1BB agonism was assessed in the HT-29 colon carcinoma xenograft model in PBMC humanized mice in combination with a T cell engager. Consistent with tumor targeting, MP0310 enhanced intra-tumoral CD8 T cell expansion while showing only limited systemic activity. We used a translational pharmacokinetic-pharmacodynamic (PK-PD) modeling approach to integrate in vitro and in vivo data to support the estimation of a minimal anticipated biological effect level (MABEL) and the relevant dose range for first in human (FIH) studies. In addition to a PK model describing the MP0310 concentrations over time in mouse and monkey, direct and indirect response models were used to describe receptor occupancy (RO), intra-tumoral CD8 T cell infiltration and peripheral CD8 count kinetics. Predictions from the combined PK and PD models using average intra-tumoral and peripheral drug concentrations (Cav) provide a MABEL dose with minimal expected systemic PD effects at 20% RO as well as the anticipated therapeutic dose range in humans. In conclusion, our PK/PD-modeling approach provides support for the selection of a safe starting dose for MP0310 (AMG506) in patients. It provides a rationale for selecting the maximum tested dose, and may help reduce the number of cancer patients receiving sub-therapeutic doses. MP0310 (AMG 506) is currently being evaluated in a Ph1 clinical study. Citation Format: Alexander Link, Laurent Juglair, Heïdi Poulet, Guy Lemaillet, Christian Reichen, Patricia Schildknecht, Ivana Tosevski, Joanna Robinson, Niina Veitonmäki, Jörg Herbst, Keith Dawson, Christof Zitt, Camila de Almeida, Rik de Greef, Victor Levitsky, Michael T. Stumpp, Hong Ji, Elmar Vom Baur. Selection of first-in-human clinical dose range for the tumor-targeted 4-1BB agonist MP0310 (AMG 506) using a pharmacokinetic/pharmacodynamics modeling approach [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 2273.

Assessment of current approaches of starting dose selection and dose escalation for oncology biologics in first-in-patient trials.

e14093 Background: Current approaches for starting dose selection for first-in-patient (FIP) trials of oncology biologics vary according to pharmacological properties and modality of the investigational agent. For biologics with immune agonistic properties, the FIP starting dose is typically based on the minimal anticipated biological effect level (MABEL). For non-immune activating biologics, the starting dose is typically based on allometric scaling of a threshold toxic dose determined in the most appropriate animal species. The aim of this work is to assess the performance of current approaches of FIP starting dose selection and dose escalation for oncology biologics. Methods: FIP clinical trials for oncology biologics licensed by the US FDA from 2010 to 2019 were analyzed to extract information related to starting dose and dose escalation. Source materials for the relevant FIP trials included the Drugs@FDA database, PubMed, and conference proceedings. The data were further analyzed to evaluate parameters related to appropriateness of the starting dose and dose escalation efficiency, which include the number of cohorts to reach the maximum tolerated dose [MTD] (or, when MTD was not identified, the highest human dose [HHD]) and the ratio of MTD/HHD to starting dose. Results: The 26 oncology biologics licensed by the US FDA between 2010 and 2019 included 8 ADCs/immunotoxins, 7 checkpoint inhibitors and 11 other biologics (monoclonal antibody, fusion protein or CD3 bispecific construct). The majority (69%) of these biologics were well tolerated without MTD identified in the FIP trials. All 26 FIP trials with biologics appeared to follow ICH S9 Guidance for starting dose selection, and the dose increment ranged from 1.2- to 10-fold. These FIP trials had a median of 6 cohorts (range: 3-10) to reach MTD (or HHD) from the starting dose. About 50% of these trials involved ≥ 6 cohorts to reach MTD (or HHD). The MTD/HHD to starting dose ratio was > 100 for 4 of the biologics. The median label dose to starting dose ratio was 10 (range: 1-3200), suggesting that a large number of patients in these FIP trials received subtherapeutic dose levels. Conclusions: Current approaches of starting dose selection and dose escalation led to a very low starting dose and many dose escalation cohorts for the FIP trials of a large portion of recently licensed oncology biologics. There exist opportunities to improve current approaches to increase FIP trial efficiency and reduce the number of patients receiving subtherapeutic dose levels in these trials.

First in human dose calculation of a single-chain bispecific antibody targeting glioma using the MABEL approach

BackgroundFirst-in-human (FIH) clinical trials require careful selection of a safe yet biologically relevant starting dose. Typically, such starting doses are selected based on toxicity studies in a pharmacologically relevant animal...

First-in-human clinical trial to assess pharmacokinetics, pharmacodynamics, safety, and tolerability of iscalimab, an anti-CD40 monoclonal antibody.

Iscalimab is a fully human, CD40 pathway blocking, nondepleting monoclonal antibody being developed as an immunosuppressive agent. We describe a first-in-human, randomized, double-blind, placebo-controlled study investigating the safety, tolerability, pharmacokinetics, and pharmacodynamics of iscalimab in healthy subjects and rheumatoid arthritis patients. Healthy subjects (n=56) received single doses of intravenous iscalimab (0.03, 0.1, 0.3, 1, or 3mg/kg), or subcutaneous iscalimab (3mg/kg), or placebo. Rheumatoid arthritis patients (n=20) received single doses of intravenous iscalimab (10 or 30mg/kg) or placebo. Iscalimab exhibited target-mediated drug disposition resulting in dose-dependent and nonlinear pharmacokinetics. Complete (≥90%) CD40 receptor occupancy on whole blood B cells was observed at plasma concentrations >0.3-0.4µg/mL. In subjects receiving 3mg/kg iscalimab, antibody responses to keyhole limpet hemocyanin were transiently suppressed. CD40 occupancy by iscalimab prevented ex vivo human rCD154-induced expression of CD69 on B cells in whole blood. All doses were generally safe and well tolerated, with no clinically relevant changes in any safety parameters, including no evidence of thromboembolic events. Iscalimab appears to be a promising blocker of the CD40-CD154 costimulatory pathway with potential use in transplantation and other autoimmune diseases.

EXTH-09. FIRST-IN-HUMAN DOSING CONSIDERATIONS OF A BISPECIFIC ANTIBODY FOR TREATING GLIOBLASTOMA

Abstract Current therapy for glioblastoma (GBM) is incapacitating and limited by non-specific toxicity to the surrounding brain. We have developed an immunotherapeutic approach that selectively targets GBM by redirecting the patients’ own T cells towards the tumor in an antigen-specific manner using a bispecific antibody. Our novel bispecific antibody (“BRITE”) binds GBM-specific surface marker EGFRvIII and the CD3 receptor on T cells, resulting in crosslinking and tumor-specific cell lysis. We previously showed in patient-derived and syngeneic murine glioma models, that treatment with BRITE leads to long-term survival in mice with glioblastoma. A pharmacokinetic analysis in a CD3 humanized mouse revealed that BRITE in plasma and whole blood has an initial half-life of ~8 minutes and a terminal half-life of ~2.5 hours. Given our preclinical success, we have initiated clinical trial-enabling studies, including studies of BRITE toxicology and GMP manufacturing of drug product. A crucial consideration for our proposed Phase 1 dose escalation trial is the starting dose in humans. To this end, we utilized the FDA-recommended minimum anticipated biological effect level (MABEL) of BRITE – a holistic approach that considers all available in vitro and in vivo data – to calculate the first-in-human starting dose of BRITE.

Imbalance in the Blood Concentrations of Selected Steroids in Pre-pubertal Gilts Depending on the Time of Exposure to Low Doses of Zearalenone.

Zearalenone (ZEN) is a mycotoxin that not only binds to estrogen receptors, but also interacts with steroidogenic enzymes and acts as an endocrine disruptor. The aim of this study was to verify the hypothesis that low doses, minimal anticipated biological effect level (MABEL), no-observed-adverse-effect level (NOAEL) and lowest-adverse-effect level (LOAEL), of ZEN administered orally for 42 days can induce changes in the peripheral blood concentrations of selected steroid hormones (estradiol, progesterone and testosterone) in pre-pubertal gilts. The experiment was performed on 60 clinically healthy gilts with average BW of 14.5 ± 2 kg, divided into three experimental groups and a control group. Group ZEN5 animals were orally administered ZEN at 5 μg ZEN/kg BW, group ZEN10 — at 10 μg ZEN/kg BW, group ZEN15 — at 15 μg ZEN/kg BW, whereas group C received a placebo. Five gilts from every group were euthanized on analytical dates 1, 2 and 3 (days 7, 14 and 42 of the experiment). Qualitative and quantitative changes in the biotransformation of low ZEN doses were observed. These processes were least pronounced in group ZEN5 (MABEL dose) where ZEN metabolites were not detected on the first analytical date, and where β-ZEL was the predominant metabolite on successive dates. The above was accompanied by an increase in the concentration of estradiol (E2) which, together with “free ZEN”, probably suppressed progesterone (P4) and testosterone (T) levels.

Pharmacokinetics, Pharmacodynamics, and Safety of E6011, a Novel Humanized Antifractalkine (CX3CL1) Monoclonal Antibody: A Randomized, Double-Blind, Placebo-Controlled Single-Ascending-Dose Study.

E6011 is a novel humanized antifractalkine (FKN) monoclonal antibody being developed as a therapeutic target for Crohn's disease, rheumatoid arthritis, and primary biliary cholangitis. This study was a randomized, double-blind, placebo-controlled single-ascending-dose study of intravenous administration of E6011 (0.0006-10mg/kg) in healthy Japanese adult men (n = 64). The starting dose was the minimum anticipated biological effect level (MABEL). MABEL was estimated by extrapolating results of a pharmacokinetic/pharmacodynamic (PK/PD) model relating E6011 exposure and suppression of free soluble FKN using data obtained from cynomolgus monkeys. Safety assessments consisted of monitoring and recording adverse events, laboratory tests, vital signs, intensive electrocardiograms, and chest x-rays. Blood samples to determine PK, PD (serum total FKN concentration), and serum anti-E6011 antibody were collected. Noncompartmental analysis was used to derive PK parameters. Single intravenous infusions of E6011 were safe and well tolerated in healthy subjects. Serum E6011 concentrations showed triphasic elimination. An increase in serum total FKN concentration was observed, confirming target engagement. The dose strategy for patient studies is to select regimens that will attain a minimum serum E6011 exposure of 10 μg/mL, identified as the minimum concentration needed to saturate the target-mediated elimination pathway. Model-based drug development from preclinical stage was successful in identifying dose regimens for clinical testing.

Current strategies in the non-clinical safety assessment of biologics: New targets, new molecules, new challenges

Nonclinical safety testing of biopharmaceuticals can present significant challenges to human risk assessment with these innovative and often complex drugs. Emerging topics in this field were discussed recently at the 2016 Annual US BioSafe General Membership meeting. The presentations and subsequent discussions from the main sessions are summarized. The topics covered included: (i) specialty biologics (oncolytic virus, gene therapy, and gene editing-based technologies), (ii) the value of non-human primates (NHPs) for safety assessment, (iii) challenges in the safety assessment of immuno-oncology drugs (T cell-dependent bispecifics, checkpoint inhibitors, and costimulatory agonists), (iv) emerging therapeutic approaches and modalities focused on microbiome, oligonucleotide, messenger ribonucleic acid (mRNA) therapeutics, (v) first in human (FIH) dose selection and the minimum anticipated biological effect level (MABEL), (vi) an update on current regulatory guidelines, International Council for Harmonization (ICH) S1, S3a, S5, S9 and S11 and (vii) breakout sessions that focused on bioanalytical and PK/PD challenges with bispecific antibodies, cytokine release in nonclinical studies, determining adversity and NOAEL for biologics, the value of second species for toxicology assessment and what to do if there is no relevant toxicology species.

Integrating data from the Investigational Medicinal Product Dossier/investigator's brochure. A new tool for translational integration of preclinical effects.

Integrating data from the Investigational Medicinal Product Dossier/investigator's brochure. A new tool for translational integration of preclinical effects.

Abstract 4088: First-in-human dose selection for ALKS 4230, an investigational immunotherapeutic agent

Abstract ALKS 4230 is an engineered fusion protein comprised of a circularly permuted interleukin-2 (IL-2) and the IL-2 receptor (IL-2R) α chain, CD25, designed to selectively activate the intermediate-affinity IL-2R, but not the high-affinity IL-2R. Selective activation of the intermediate-affinity IL-2R by ALKS 4230 has the potential to provide enhanced tumor killing as well as improved safety and tolerability. Various in vitro and in vivo studies were conducted to characterize the primary and secondary pharmacodynamics (PD) of ALKS 4230 as well as its pharmacokinetics (PK). The results guided the selection of the starting dose for the ALKS 4230 first-in-human (FIH) clinical study based upon the Minimal Anticipated Biological Effect Level (MABEL) approach. The PK-PD relationship for ALKS 4230 was evaluated in in vitro pharmacology studies in target cells from murine, non-human primate and human donors. The mean EC10 values for activation of NK cells, memory CD8 T-cells and Tregs in target cells from human donors were 0.09, 0.18 and 0.13 nM, respectively. Using the lowest EC10 value of 0.09 nM (0.0031µg/mL) as a surrogate for the MABEL, assuming IV administration to a 70 kg human with 3 L plasma volume, a dose of 0.1 µg/kg would be expected to result in an immediate post-dose concentration of 0.0031 µg/mL. The mean EC50 values for activation of NK cells, memory CD8 T cells and Tregs in target cells from human donors were 0.46, 1.1 and 0.59 nM, respectively. Using the EC50 value as surrogate for minimal effective ALKS 4230 concentration that induces activation of human IL-2R complex, the projected minimal efficacious dose (MED) in humans to achieve a concentration of 0.46 nM (0.016 µg/mL) to 1.1 nM (0.038 µg/mL) is 0.7- 1.6 µg/kg. Based on a MABEL dose of 0.1 µg/kg and projected MED of 0.7- 1.6 µg/kg, the proposed doses to be evaluated in the FIH Phase 1 study are 0.1, 0.3, 1, 3, 10, and 30 µg/kg. In comparison, the projected Cmax at the proposed starting dose of 0.1 µg/kg is > 750-fold lower than the Cmax at the no-observed adverse effect level (NOAEL) in a repeat-dose toxicology study in monkeys. It is also about 3-fold lower than the lowest concentration of ALKS 4230 (0.01 µg/mL) tested in the cytokine release assays at which only slight elevations were observed for IL-6, IL-8, and IFN-γ in a small number of whole blood samples from healthy human donors, similar to those in the low-response control across the concentration range evaluated. Therefore, 0.1 µg/kg is considered a safe starting dose for the FIH study. The PK, PD and toxicology assessments conducted to date support the FIH investigation of ALKS 4230 at the proposed starting dose of 0.1 µg/kg. Citation Format: Lei Sun, Heather C. Losey, Juan Alvarez, Lisa von Moltke, William J. Slichenmyer. First-in-human dose selection for ALKS 4230, an investigational immunotherapeutic agent [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4088. doi:10.1158/1538-7445.AM2017-4088