Full Receptor Occupancy Research Articles

A phase 1 study of REGN6569, a GITR mAb, in combination with cemiplimab in patients (pts) with advanced solid tumor malignancies: Initial dose-escalation results.

2650 Background: REGN6569 is a fully human immunoglobulin G1 monoclonal antibody (mAb) that is highly specific for glucocorticoid-induced tumor necrosis factor receptor–related protein (GITR). GITR is expressed on several immune cell subtypes, notably regulatory T cells (Tregs), and activated natural killer (NK) cells. REGN6569 demonstrated greater in vitro antibody-dependent cell-mediated cytotoxicity against GITR-expressing Tregs, as compared to GITR-expressing CD8+ T cells. Mouse studies showed that REGN6569 + cemiplimab (anti-PD-1) combination treatment achieved longer-term tumor responses compared with either drug alone. Methods: This is a first-in-human study (NCT04465487) evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity of REGN6569 administered intravenously (IV) every 3 weeks (Q3W) + cemiplimab 350 mg IV Q3W, in pts with advanced solid tumors for which immune checkpoint inhibitor therapies have not been approved or are not available. The study includes a dose-escalation part with 5 dose levels (DL1-DL5) for REGN6569 (“4+3” design), with an initial dose of REGN6569 monotherapy given as a safety lead-in followed by REGN6569 + cemiplimab in subsequent doses. Results: As of the data cutoff date Oct 20, 2023, the dose-escalation part has been completed. 29 pts (median age 58.0 years, 62.1% male) were treated with REGN6569 + cemiplimab, up to the 1200 mg dose level (DL5), across many solid tumor types. The most common tumor type was colorectal cancer (34.5%). One pt (40 mg DL2) experienced a dose-limiting toxicity (Grade 3 hepatic failure); maximum tolerated dose was not reached. Twelve pts (41.4%) had a Grade ≥3 treatment-emergent adverse event (TEAE) and 16 pts (55.2%) had a treatment-related TEAE (any grade). The most frequent TEAEs (any grade) were arthralgia (24.1%), infusion-related reactions, and abdominal pain (20.7% each). There were no treatment-related deaths; 19 (65.5%) pts had disease progression leading to death. Two pts achieved ongoing partial responses by investigator assessment with REGN6569 + cemiplimab treatment: 1 pt with mucoepidermoid tumor of the parotid gland treated with 120 mg (DL3) REGN6569 and 1 pt with B3 thymoma treated with 400 mg (DL4) REGN6569, with duration of responses, 5.6 and 10.4 months, respectively. Full receptor occupancy on circulating Tregs was observed in all dose cohorts following REGN6569 treatment. Increased frequency (~10–50%) of proliferating NK cells in peripheral blood was observed post REGN6569 treatment across all dose cohorts. Conclusions: In this dose-escalation study, REGN6569 was administered up to 1200 mg (DL5) in combination with cemiplimab with one dose-limiting toxicity. The study has progressed to dose-expansion cohorts in anti–PD-1-resistant head and neck cancer, with pts treated with REGN6569 (DL5) + cemiplimab. Clinical trial information: NCT04465487 .

EVICTION study: ICT01, an anti-Butyrophilin 3A monoclonal antibody activating γ9δ2 T cells in combination with pembrolizumab in checkpoint inhibitor refractory melanoma.

9534 Background: γ9δ2 T-cell tumor infiltration is associated with a favorable prognosis making these cells a new potential target for immunotherapy. The anti-BTN3A mAb ICT01 selectively activates γ9δ2 T cells and is being studied in the phase1/2a EVICTION Trial (NCT04243499). In preclinical studies, ICT01 induces upregulation of PD-1 on γ9δ2 T-cells and combination with pembrolizumab leads to enhanced cancer cell killing, providing scientific rationale to evaluate this combination. Here we present interim results from EVICTION of ICT01 in combination with pembrolizumab in patients with checkpoint inhibitor (CPI) refractory melanoma. Methods: EVICTION evaluated ICT01 (20 µg to 200 mg, Q3W) plus pembrolizumab (200mg IV Q3W) in a dose escalation solid tumor basket design that resulted in an ongoing expansion cohort of patients with CPI refractory melanoma (2 dose levels, 7 and 200 mg ICT01). Patients are selected based on higher baseline γ9δ2 T cells. Efficacy evaluations by i/RECIST 1.1 are conducted every 8 weeks. Disease Control Rate (DCR) as primary efficacy endpoint is defined as the sum of complete response (CR), partial response (PR) and stable disease (SD, minimum week 16). Baseline and on-treatment blood and biopsy specimens are collected for correlative translational work. Results: ICT01 plus pembrolizumab has a favorable safety profile with first-dose Grade 1/2 infusion related reactions (IRR) and cytokine release syndrome (CRS) as most common adverse events (in 38% and 19% of patients respectively, 5%and 2% Grade 3) among all doses and indications. To date, 35 CPI refractory melanoma patients have been enrolled, of which 65% have received 2+ prior lines of CPI. Currently 21 patients are evaluable at week 16 with a DCR of 42% (including 3 PR) and a 6-month progression free survival of 38%. In the circulation, full BTN3A receptor occupancy on immune cells was achieved at 7 mg dose, with down-modulation of BTN3A observed at doses greater than 20 mg. Clinical response was related to baseline tumoral BTN3A expression, sustained elevation of IFNg levels, and tumor microenvironment remodeling, including increased PD-L1 expression and CD8 T cells proliferation and activation. Conclusions: ICT01 in combination with pembrolizumab has a favorable safety profile and promising efficacy data. Patient selection based on BTN3A tumor expression will be further evaluated as an enrichment strategy. Clinical trial information: NCT04243499 .

DOP81 Rosnilimab, a novel PD-1 agonist monoclonal antibody, reduces T cell proliferation, inflammatory cytokine secretion, and PD-1high expressing CD4 and CD8 T cells: Results from a Phase 1 healthy volunteer clinical trial

Abstract Background Programmed cell death protein 1 (PD-1) is expressed on activated T cells and is a key co-inhibitory node in immune regulation. By targeting regulatory mechanisms to modulate immune cells driving disease, there is an opportunity to restore immune balance. Rosnilimab is a PD-1 agonist antibody designed to reduce T cell proliferation and inflammatory cytokine secretion and deplete PD-1high T follicular helper, T peripheral helper, and T effector cells. It is being studied for ulcerative colitis (UC), where PD-1+ T cells are prevalent in inflamed lamina propria (>40%) and the periphery. The primary objective of this healthy volunteer Phase 1 study was to assess the safety and tolerability of single ascending doses (SAD) and multiple ascending doses (MAD) of rosnilimab. Findings from pharmacokinetic (PK) and pharmacodynamic (PD) assessments are summarized. Methods This single-centre study included 14 cohorts in SAD and 3 cohorts in MAD. Each cohort had 8 participants (6 active, 2 placebo [PBO]). Cohorts were enrolled sequentially in each phase. Intravenous (IV) and subcutaneous (SC) administration were assessed in SAD; SC route was assessed in MAD. Results A total of 144 participants were enrolled; 90 to active SAD cohorts, 18 to active MAD cohorts, and 30 and 6 to SAD and MAD PBO cohorts, respectively. Rosnilimab was well tolerated with no dose-limiting toxicities or deaths. Two serious adverse events were reported in SAD (deemed unrelated to treatment) and 0 in MAD. PD-1 expressing cells were reduced by ~50% in both CD4+ and CD8+ subsets, in a dose-dependent manner and in correlation with full receptor occupancy (RO) through Day 30 in SAD. PD activity was rapid with sustained reduction in PD-1+ T cells, and ex-vivo stimulation resulted in reduced T cell functional activity. This reduction was maximized on PD-1high expressing T cells: ~90% reduction vs baseline. There was no significant impact on the overall total T cell or regulatory T (Treg) cell numbers, resulting in restoration of T cell composition to a less activated state and a positive shift in the Treg:Teff ratio. An antigen-specific functional T cell assay measuring ex vivo interferon-gamma release in response to antigen challenge was inhibited up to ~90% vs baseline and the response lasted for more than 30 days following a single dose. Rosnilimab had a favourable PK profile consistent with full RO, a 2-week half-life, and dose-proportional exposure in IV and SC dosing. Conclusion Rosnilimab demonstrated favourable safety, PK, and PD activity. The role of PD-1 in UC pathophysiology coupled with these results and translational data, demonstrate proof of mechanism and support progression into a Phase 2 study of rosnilimab in UC. (NCT06127043)

Validation of a pharmacological imaging challenge using 11C-buprenorphine and 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography to study the effects of buprenorphine to the rat brain.

Buprenorphine mainly acts as an agonist of mu-opioid receptors (mu-OR). High dose buprenorphine does not cause respiratory depression and can be safely administered to elicit typical opioid effects and explore pharmacodynamics. Acute buprenorphine, associated with functional and quantitative neuroimaging, may therefore provide a fully translational pharmacological challenge to explore the variability of response to opioids in vivo. We hypothesized that the CNS effects of acute buprenorphine could be monitored through changes in regional brain glucose metabolism, assessed using 18F-FDG microPET in rats. First, level of receptor occupancy associated with a single dose of buprenorphine (0.1 mg/kg, s.c) was investigated through blocking experiments using 11C-buprenorphine PET imaging. Behavioral study using the elevated plus-maze test (EPM) was performed to assess the impact of the selected dose on anxiety and also locomotor activity. Then, brain PET imaging using 18F-FDG was performed 30 min after injection of unlabeled buprenorphine (0.1 mg/kg, s.c) vs. saline. Two different 18F-FDG PET acquisition paradigms were compared: (i) 18F-FDG injected i.v. under anesthesia and (ii) 18F-FDG injected i.p. in awake animals to limit the impact of anesthesia. The selected dose of buprenorphine fully blocked the binding of 11C-buprenorphine in brain regions, suggesting complete receptor occupancy. This dose had no significant impact on behavioral tests used, regardless of the anesthetized/awake handling paradigm. In anesthetized rats, injection of unlabeled buprenorphine decreased the brain uptake of 18F-FDG in most brain regions except in the cerebellum which could be used as a normalization region. Buprenorphine treatment significantly decreased the normalized brain uptake of 18F-FDG in the thalamus, striatum and midbrain (p < 0.05), where binding of 11C-buprenorphine was the highest. The awake paradigm did not improve sensitivity and impact of buprenorphine on brain glucose metabolism could not be reliably estimated. Buprenorphine (0.1 mg/kg, s.c) combined with 18F-FDG brain PET in isoflurane anesthetized rats provides a simple pharmacological imaging challenge to investigate the CNS effects of full receptor occupancy by this partial mu-OR agonist. Sensitivity of the method was not improved in awake animals. This strategy may be useful to investigate de desensitization of mu-OR associated with opioid tolerance in vivo.

Cellular and In Vivo Preclinical Pharmacodynamics and Pharmacology of Nipocalimab, an Anti-FcRn Blocking Therapeutic Antibody (P10-5.011)

<h3>Objective:</h3> To characterize the mechanism of action, pharmacodynamics and pharmacology of nipocalimab in preclinical models. <h3>Background:</h3> Nipocalimab is a fully human antibody being evaluated in over 10 autoantibody diseases including MG and CIDP. Nipocalimab binds with high affinity to the neonatal Fc receptor (FcRn) inhibiting IgG recycling and inducing autoantibody destruction while permitting key immune functions including IgG production. Here, the molecular, cellular and in vivo pharmacology of nipocalimab are shown to be well aligned with the pharmacodynamic and pharmacological effects observed in MG patients. <h3>Design/Methods:</h3> Nipocalimab in vitro receptor occupancy (RO) was assessed in a fluorescence-activated cell sorting assay in human aortic endothelial cells. In vivo, RO in circulating monocytes and total serum IgG were evaluated in human FcRn transgenic mice (Tg32 strain) or cynomolgus monkeys after i.v. infusions of up to 100 or 300 mg/kg nipocalimab, respectively. <h3>Results:</h3> Nipocalimab exposure at picomolar concentrations results in full RO within 30 minutes and inhibits IgG recycling in endothelial cells. In vivo, full RO was established within 2 hours in mice and 4 hours in monkeys and maintained at picomolar concentrations. The onset of IgG lowering due to inhibition of IgG recycling was detected within 1–2 days and was maintained during the period of full FcRn saturation. Duration of RO in peripheral blood monocytes in both preclinical species was dose-dependent, as was the duration of IgG clearance, suggesting a relationship between RO and maintenance of an increased IgG clearance rate. Nipocalimab in vitro FcRn RO and IgG recycling correlated well with in vivo RO and IgG lowering. <h3>Conclusions:</h3> Nipocalimab is a potent FcRn blocker inducing rapid and sustained lowering of IgG and IgG autoantibodies in preclinical studies. These results are consistent with findings from the phase 1 healthy volunteer (NCT02828046) and phase 2 VIVACITY study in gMG patients (NCT03772587). <b>Disclosure:</b> Dr. Ling has received personal compensation for serving as an employee of Janssen Pharmaceuticals (Johnson&amp;Johnson). Dr. Ling has stock in Janssen Pharmaceuticals (Johnson&amp;Johnson). Dr. Ling has received intellectual property interests from a discovery or technology relating to health care. Dr. Ling has received intellectual property interests from a discovery or technology relating to health care. Dr. Choudhury has stock in Janssen Pharmaceuticals. Mr. Tyler has received personal compensation for serving as an employee of AVROBIO, INC . Mr. Tyler has received personal compensation for serving as an employee of Orna Therapeutics. Mr. Tyler has received personal compensation for serving as an employee of Genevant Sciences. Dr. Avery has received personal compensation for serving as an employee of Lyndra Therapeutics. Dr. Avery has received personal compensation for serving as an employee of Xilio Therapeutics. Dr. Avery has received personal compensation for serving as an employee of Kisbee Therapeutics. Dr. Avery has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Momenta Pharmaceutical. Dr. Avery has received stock or an ownership interest from Life Biosciences.

Abstract CT040: 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: Dose escalation study

Abstract Background: IO-108 is a fully human IgG4 monoclonal antibody with high affinity and specificity towards LILRB2 (also known as ILT4). It blocks the interaction of LILRB2 with the known ligands for LILRB2, including HLA-G, ANGPTLs, SEMA4A and CD1d. Methods: IO-108-CL-001 is a first-in-human, Phase 1a/1b study in patients with relapsed/refractory solid tumors (NCT05054348). The dose escalation phase enrolled patients into escalating dose cohorts of IO-108 (60-1800 mg, Q3W IV) as monotherapy or in combination with pembrolizumab. Patients with disease progression on monotherapy could crossover to the combination arm. Primary objectives were safety and tolerability, and identification of the recommended phase 2 dose (RP2D). Secondary and exploratory objectives include evaluation of pharmacokinetics (PK), immunogenicity, pharmacodynamic (PD) biomarker effects and anti-tumor activity as measured by objective response rate (RECIST 1.1). Results: Twenty-five relapsed/refractory solid tumor patients (median 4.5 prior lines of therapy for monotherapy and 3.6 for combination therapy) were treated with IO-108 monotherapy (n=12) or IO-108 + pembrolizumab (n=13). IO-108 was well-tolerated up to the maximal administered dose of 1800 mg Q3W as monotherapy and in combination with pembrolizumab, with no SAEs related to IO-108 and no DLTs observed. Maximum tolerated dose (MTD) was not reached. Full receptor occupancy through 21 days was achieved at ≥600 mg. The preliminary RP2D is 1200 mg Q3W. Dose-expansion cohorts of IO-108 monotherapy and IO-108 + anti-PD-1 are ongoing.Twenty-three patients were efficacy evaluable (11 monotherapy, 12 combination therapy plus 1 crossover). Overall response rate was 9% in monotherapy cohort (1 Merkel cell carcinoma, prior pembrolizumab followed by nivolumab/ipilimumab) and 23% in combination therapy (2 cholangiocarcinoma, 1 MSS CRC with neuroendocrine features)​. The best overall response was 1 CR, 4 SD among monotherapy, and was 3 PR, 4 SD among combination therapy.​ The 4 responding patients remain on study with an on-going treatment duration of 8 to 12 months as of abstract submission.Consistent with the MOA, clinical benefit correlated with baseline characteristics and post-treatment changes in PD biomarkers including reprogramming of myeloid cells and activation of T cells. Conclusion: The initial encouraging data support further development of IO-108, both as monotherapy and in combination with anti-PD-(L)1 for patients with advanced solid tumors. Citation Format: Matthew H. Taylor, Manish R. Patel, John D. Powderly, Paul Woodard, Luke Chung, Hongyu Tian, Xiang Hong, Kyu Hong, Donna Valencia, Tao Huang, Xiao Min Schebye, Charlene Liao, Aung Naing. 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: Dose escalation study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT040.

Abstract 2129: Predictive response biomarkers from Phase I clinical trial of a SIRPalpha inhibitor BI765063, stand-alone and in combination with ezabenlimab, a PD1 inhibitor, in patients with advanced solid tumors

Abstract Background: Signal Regulatory Protein α [SIRPα] is an inhibitory membrane receptor expressed by myeloid cells (macrophages and myeloid-derived suppressor cells, MDSCs) and specifically binds to CD47. BI765063 is a selective anti-SIRPα monoclonal antibody acting as a checkpoint inhibitor of SIRPα/CD47 axis, promoting anti-tumor immunity through increase of dendritic cells antigen presentation, enabling MDSC differentiation, potentiating macrophage phagocytic/inflammatory properties and reinstating myeloid cell chemokine secretion and human T cell migration1. The escalation phase I study in advanced solid tumor patients (pts) showed preliminary efficacy as monotherapy (MONO), and in combination with PD-1 inhibitor ezabenlimab (COMBO). Our goal was to investigate BI765063 predictive response markers. Methods: A total of 68 patients (50 in MONO arm, 18 in COMBO arm) have been enrolled. Receptor occupancy (RO) was determined on peripheral CD14+ monocytes. Tumor biopsies were collected before treatment from 44 pts (62%) representative of overall population. Tumor microenvironment (TME) was analysed using a Brightplex® IHC panel comprised of CD68+ macrophages, CD11b+myeloid cells, SIRPα, and CD47. NanoString tumor profiling used PanCancer IO360 panel. Results: One partial response (PR) in MONO (Hepatocellular carcinoma HCC), and 4 PRs in COMBO (2 endometrial cancer, 1 HCC, 1 iRecist PR in MSS CRC) were observed2. BI 765063 full RO saturation was achieved in V1/V1 pts treated with doses of 6 mg/kg and higher, while V1/V2 patients showed a more heterogeneous RO ranging between 40-80%, reaching an apparent saturation at doses of 12 mg/kg and higher. Comparison of pts by best response showed that baseline tumor SIRPα+ expression in CD68+ macrophages and in CD11b+ myeloid cells were higher in PR versus PD pts. High percentage of CD11b+SIRPα+ myeloid cells at baseline significantly correlated with better OS (p=0.023), while CD68+SIRPα+ macrophages high expression in TME showed a trend for a better OS but did not reach statistical significance. The CD47 tumor expression did not correlate with the OS. Responder signature based on the top deregulated genes in responders versus non-responders at baseline was devised to sort relevant TCGA cohorts and showed strong positive correlation with TME MDSC infiltration (p≤0.0001). Conclusions: High levels of CD11b+SIRPα+ myeloid cells in TME at baseline, but not CD47 tumor expression, correlates with longer survival while MDSC signature in TME at baseline correlates with clinical response. Thus, suggesting that MDSCs expressing SIRPα in TME could represent a predictive efficacy biomarker.

Single dose tocilizumab for COVID-19 associated cytokine storm syndrome: Less is more.

We aim to evaluate the clinical pharmacokinetics of a single dose interleukin-6 (IL-6) antibody tocilizumab (TCZ) in methylprednisolone (MP)-treated COVID-19 patients with cytokine storm syndrome (CSS). MP pre-treated patients with COVID-19-associated CSS, defined as at least two elevations of C-reactive protein (CRP) >100 mg/L, ferritin >900 μg/L or D-dimers >1500 μg/L, received intravenous TCZ (8mg/kg, max. 800 mg) upon clinical deterioration. A nonlinear-mixed effects model was developed based on TCZ serum concentrations and dosing information. Population pharmacokinetic parameters were estimated and concentration-time profiles were plotted against individual predicted values. Fixed dose simulations were subsequently performed based on the final model. In total 40 patients (mean [SD] age: 62 [12] years, 20% female, body weight: 87 [17] kg) with COVID-19 induced CSS were evaluated on pharmacokinetics and laboratory parameters. A biphasic elimination of TCZ serum concentration was described by a homogeneous population pharmacokinetic model. Serum TCZ concentrations above the 1μg/L target saturation threshold were covered for 16 days in all evaluated patients treated with a single dose of 8mg/kg. In a simulation with TCZ 400 mg fixed dose, this condition of full IL-6 receptor occupancy at minimum serum concentration was also met. A single dose (8mg/kg, max. 800 mg) is sufficient to cover a period of 16 days of IL-6-mediated hyperinflammation in COVID-19-induced CSS in MP-treated patients. Based on body weight PK simulations, a fixed-dose tocilizumab of 400 mg should be considered to prevent overtreatment, future drug shortage and unnecessary drug expenditure.

Abstract CT198: Subcutaneous delivery of amivantamab in patients with advanced solid malignancies: Initial safety and pharmacokinetic results from the PALOMA study

Abstract Background: Amivantamab, an epidermal growth factor receptor (EGFR)-MET bispecific antibody, is approved for patients with advanced EGFR exon 20 insertion non-small cell lung cancer after progression on platinum-based chemotherapy. First-dose intravenous (IV) delivery leads to infusion-related reactions (IRR) among 66% of patients, resulting in dose interruptions and slower infusion restart rates (infusion duration ranges 2-4 hours) and necessitates splitting of the dose over 2 days (Park Ann Oncol 32[suppl_5]:S981). Subcutaneous (SC) administration of amivantamab, which could simplify and accelerate administration, is being investigated in an ongoing phase 1 study (PALOMA; NCT04606381). Preliminary safety (including IRR) and pharmacokinetics (PK) of SC formulations of amivantamab ± recombinant human hyaluronidase (rHuPH20) for enhanced absorption were evaluated. Methods: PALOMA is an ongoing phase 1 dose escalation study of amivantamab SC in patients with advanced solid tumors who may derive benefit from EGFR or MET-directed therapy. Eligible patients must have progressed after standard-of-care therapy for metastatic disease, be ineligible for, or have declined current standard therapies. The study objectives were to evaluate the feasibility of administration, safety, and PK of a low concentration formulation, 50 mg/mL of amivantamab ± rHuPH20 (Part 1) and a high concentration formulation, 160 mg/mL of amivantamab ± rHuPH20 (Part 2). Patients in Part 1 and Part 2 received the currently approved dosage of amivantamab, 1050 mg (1400 mg for bodyweight ≥80 kg) SC (weekly for the first 4 weeks and every other week thereafter). This study also evaluated administering the full dose of amivantamab on the first day. Results: The full safety, PK, bioavailability, and receptor occupancy data of patients enrolled in Part 1 (n=16) and Part 2 (n=17) will be presented. Compared to IV administration, initial SC experience demonstrates the co-formulation of high concentration amivantamab with rHuPH20 shortened the needed infusion time to less than 5 minutes, with initial bioavailability of approximately 65% of IV administration. Saturation of soluble free EGFR and MET was achieved after the first SC dose. The incidence of IRRs was 18.2%, with all events of grade 1-2 severity. The full amivantamab SC dose was safely given at first administration to 14 patients, potentially obviating the need for split dosing. Conclusions: Initial SC amivantamab ± rHuPH20 was well tolerated with improvements in time and ease of administration and associated with a meaningful reduction in IRRs, eliminating the need for split dosing compared with IV administration. Higher SC dose levels and alternative dosing schedules are being explored. Citation Format: Matthew G. Krebs, Melissa L. Johnson, Byoung Chul Cho, Se-Hoon Lee, Rachel Kudgus-Lokken, Donna Zemlickis, Anna Mitselos, Eileen Berkay, Joshua M. Bauml, Roland E. Knoblauch, Peter Hellemans, Anna Minchom. Subcutaneous delivery of amivantamab in patients with advanced solid malignancies: Initial safety and pharmacokinetic results from the PALOMA 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 CT198.

Abstract 1993: Biomarker analyses from the Phase I clinical trial of the first-in-class SIRPa immune checkpoint inhibitor BI765063 in patients with advanced solid tumors

Abstract Background: BI 765063 (OSE-172) is a humanised IgG4 monoclonal antibody which binds selectively to the V1 allele of Signal Regulatory Protein α [SIRPα] blocking the SIRPα/CD47 “don't eat me” pathway. Preclinical studies showed that SIRPα blockage led to macrophage and T-cell recruitment into tumor xenografts, and induced upregulation of chemokines, cytokines and adaptive immune function genes in human tumor explants (Gauttier et al., 2020). The goal of the biomarker analyses was to characterize the BI 765063 impact on peripheral blood immune cells (PBMCs) and the tumor microenvironment (TME). Methods: Fifty patients (26 V1/V1, 24 V1/V2) received BI 765063 IV from 0.02 mg/kg to 36 mg/kg every 3 weeks. Paired tumor biopsies were collected before and 2 weeks after first BI 765063 infusion. PBMCs were collected before, then 4 h, 1, 14, and 21 days after first infusion. BI 765063 receptor occupancy (RO) was determined on peripheral CD14+ monocytes. Immunophenotyping of PBMCs was performed by flow-cytometry. TME was analysed with a Brightplex® IHC panel including CD8+ T-cells, CD68+ macrophages, SIRPα, CD47, and PD-L1. Tumor gene expression profiling was performed using the Pan Cancer Immune gene set. Results: BI 765063 full RO saturation was achieved at trough levels (C2D1, pre-dose) in V1/V1 patients treated with doses of 6 mg/kg and higher, while V1/V2 patients showed a more heterogeneous RO ranging from 40-80%, reaching an apparent saturation at ≥ 12 mg/kg. An increase of activated CD80+/CD14+ and CD40+/CD14+ monocytes in PBMCs was observed at 24 h post-treatment in both, V1/V1 and V1/V2 patients. In paired tumor biopsies, IFNγ, MHCII antigen presentation gene pathways, and CCL7 transcripts appeared to be upregulated at C1D15 in patients with a systemic exposure of ≥ 100 µg/ml. One patient with hepatocellular carcinoma (HCC) and liver and lung metastases treated with BI 765063 monotherapy at 24 mg/kg achieved partial response (Champiat et al., ASCO, 2021). Baseline tumor biopsy of that patient showed that 66% of HCC tumor cells were CD47+ and 87% of CD68+ macrophages were SIRPα+. Furthermore, high levels of CD8+ T-cells were observed at baseline. At C1D15 increased CD68+ macrophage infiltration, sustained CD8 T-cell tumor accumulation and higher PD-L1 CPS (48% at baseline vs 75% at C1D15) were observed. Analysis of paired tumor biopsies in other patients showed that often, increased levels of tumor CD68+ macrophages were accompanied by CD8+ T-cell infiltration. Conclusion: This early biomarker analysis in patients with a wide range of solid tumors and treated with the first-in-class SIRPa inhibitor BI 765063 show encouraging signs of potentially mode-of-action related changes, both in peripheral blood and the TME. These early signals will be further evaluated in similar samples from the ongoing expansion cohorts in more homogeneous patient populations. Citation Format: Stephane Champiat, Philippe A. Cassier, Nuria Kotecki, Carlos Gomez-Roca, Aurélien Marabelle, Armelle Vinceneux, Christiane Jungels, Mabrouk Elgadi, Ralph Graeser, Thomas Vandewalle, Isabelle Girault, Nina Salabert-Le Guen, Nicolas Poirier, Bérangère Vasseur, Dominique Costantini, Claudia Fromond, Jean-Pierre Delord. Biomarker analyses from the Phase I clinical trial of the first-in-class SIRPa immune checkpoint inhibitor BI765063 in patients with advanced solid tumors [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 1993.

Interim Results from the First Clinical Study of CC-95251, an Anti-Signal Regulatory Protein-Alpha (SIRPα) Antibody, in Combination with Rituximab in Patients with Relapsed and/or Refractory Non-Hodgkin Lymphoma (R/R NHL)

Interim Results from the First Clinical Study of CC-95251, an Anti-Signal Regulatory Protein-Alpha (SIRPα) Antibody, in Combination with Rituximab in Patients with Relapsed and/or Refractory Non-Hodgkin Lymphoma (R/R NHL)

Phase 1/2a Clinical Trial of BI-1206, a Monoclonal Antibody to Fcγriib, in Combination with Rituximab in Subjects with Indolent B-Cell Non-Hodgkin Lymphoma That Has Relapsed or Is Refractory to Rituximab

Phase 1/2a Clinical Trial of BI-1206, a Monoclonal Antibody to Fcγriib, in Combination with Rituximab in Subjects with Indolent B-Cell Non-Hodgkin Lymphoma That Has Relapsed or Is Refractory to Rituximab

Safety, pharmacokinetics, efficacy, and preliminary biomarker data of first-in-class BI 765063, a selective SIRPα inhibitor: Results of monotherapy dose escalation in phase 1 study in patients with advanced solid tumors.

2623 Background: BI 765063 is a humanized IgG4 monoclonal antibody antagonist of SIRPα (Signal Regulatory Protein α), which blocks the “don't eat me” signal of the SIRPα/CD47 axis, a critical innate immune checkpoint. SIRPα is expressed on myeloid cells. BI 765063 binds to the V1 SIRPα allele with high affinity and to the V2 SIRPα allele with low affinity. BI 765063 lacks SIRPγ binding to preserve T-cell activation. We report results of the completed BI 765063 monotherapy dose escalation in patients with advanced solid tumors. Methods: This study involves a step 1 dose escalation to determine the dose-limiting toxicities (DLT) and maximum tolerated dose (MTD), then a step 2 dose-confirmation expansion at recommended phase 2 dose. In Step 1, BI 765063 ascending doses, given IV every 3 weeks, were tested using a Bayesian Logistic Regression Model (BLRM) approach with overdose control. The endpoints were safety, pharmacokinetics, receptor occupancy (RO) in peripheral CD14+ monocytes and efficacy (RECIST 1.1). Results: Fifty patients (26 V1/V1, 24 V1/V2) received at least one dose of BI 765063. The most frequent tumors were ovarian (9), colorectal (8), lung (5), breast (4), melanoma (3), and kidney (3). No DLTs were reported up to the highest dose tested. MTD was not reached. The most frequent related adverse events were infusion related reaction (IRR) (46%), fatigue (12%), headache (10%), arthralgia and diarrhea (8% each). All related adverse events were mild to moderate, except one case of IRR Grade 3. No related anemia nor thrombocytopenia were observed. BI 765063 showed dose proportional exposure and full RO saturation in Cycle 1 after the fourth dose level. Clinical benefit was observed in 21/47 (45%) patients evaluable per RECIST 1.1. One patient with hepatocellular carcinoma (HCC) with liver and lung metastases and 7 prior lines of therapy showed a durable partial response maintained for 27 weeks treatment (ongoing). The baseline tumor biopsy of this patient showed high CD8 T-cell and macrophage infiltration. There was an increase in CD8 T-cell infiltration and activation on treatment. An increase in PD-L1 expression on tumor cells 2 weeks after first dosing was also observed. Analysis of paired tumor biopsies in other patients is ongoing. Conclusions: The first-in-class SIRPα inhibitor BI 765063 was well-tolerated, showed monotherapy activity, and sustained RO saturation. A durable partial response was observed in an advanced HCC patient. The on-treatment biopsy of the responder showed an increase in CD8 T-cell infiltration and activation. PD-L1 expression on tumor cells also increased. BI 765063 dose escalation in combination with ezabenlimab (anti-PD1 antibody) is ongoing. Clinical trial information: NCT03990233.

Evaluating the Therapeutic Efficacy of Mono- and Bivalent Affibody-Based Fusion Proteins Targeting HER3 in a Pancreatic Cancer Xenograft Model.

Human epidermal growth factor receptor 3 (HER3) has been increasingly scrutinized as a potential drug target since the elucidation of its role in mediating tumor growth and acquired therapy resistance. Affibody molecules are so-called scaffold proteins with favorable biophysical properties, such as a small size for improved tissue penetration and extravasation, thermal and chemical stability, and a high tolerance to modifications. Additionally, affibody molecules are efficiently produced in prokaryotic hosts or by chemical peptide synthesis. We have previously evaluated the biodistribution profiles of five mono- and bivalent anti-HER3 affibody molecules (designated as 3) fused to an albumin-binding domain (designated as A), 3A, 33A, 3A3, A33, and A3, that inhibit ligand-dependent phosphorylation. In the present study, we examined the therapeutic efficacy of the three most promising variants, 3A, 33A, and 3A3, in a direct comparison with the HER3-targeting monoclonal antibody seribantumab (MM-121) in a preclinical BxPC-3 pancreatic cancer model. Xenografted mice were treated with either an affibody construct or MM-121 and the tumor growth was compared to a vehicle group. Receptor occupancy was estimated by positron emission tomography/computed tomography (PET/CT) imaging using a HER3-targeting affibody imaging agent [68Ga]Ga-(HE)3-Z08698-NODAGA. The affibody molecules could inhibit ligand-dependent phosphorylation and cell proliferation in vitro and demonstrated tumor growth inhibition in vivo comparable to that of MM-121. PET/CT imaging showed full receptor occupancy for all tested drug candidates. Treatment with 3A and 3A3 affibody constructs was more efficient than with 33A and similar to the anti-HER3 antibody seribantumab, showing that the molecular design of affibody-based therapeutics targeting HER3 in terms of the relative position of functional domains and valency has an impact on therapeutic effect.

851 Targeted Intracecal anti-α4β7 Integrin Antibody Results in Reduce Accumulation of α4β7 Memory T-cells in Gut Tissue in DSS-induced Colitis Mice

INTRODUCTION: Systemically administered anti-α4β7 integrin antibodies such as Vedolizumab have been approved for the treatment of Crohn's disease and ulcerative colitis. The objective of this study was to assess whether intracecally (IC) delivered anti-mouse α4β7 integrin antibody (DATK32) might penetrate the mucosa and confer efficacy compared with systemic intraperitoneal (IP) injection in DSS-induced colitis mice. METHODS: Animals underwent implantation of a cecal cannula for topical bolus delivery in the IC groups. Acute colitis was induced by exposure to 3% DSS drinking water from Day 0-5. DATK32 was administrated via IP (25 mg/kg) every 3 days (Q3D), IC (25 mg/kg) Q3D, or IC (25 or 5 mg/kg) every day (QD) from Day 0 to 14. At Day 14, plasma, colon content and tissue were collected for DATK32 measurement; and Peyer’s patches (PP), mesenteric lymph nodes (mLN), and whole blood were collected for α4β7 memory T-cell counts. RESULTS: Significantly higher colon content and tissue exposure but limited blood exposure of DATK32 were found in IC QD groups compared to IP Q3D group. Immunohistochemistry staining of DATK32 was found in all layers of colon tissue, and as deep as tunica muscularis when delivered IC. The α4β7 memory T-cell count was significantly reduced in mLN in all IC groups compared to vehicle control and IP groups. Similar findings were observed in PP with IC QD treatment. Finally, the α4β7 memory T-cell count in blood was significantly increased in IC QD but not IC Q3D groups compared to vehicle control and IP group. CONCLUSION: In this study, we demonstrated that targeted IC anti-α4β7 integrin antibody lead to significantly higher drug exposure in colon contents and tissues with limited blood exposure compared to IP. Targeted IC QD treatment showed a significantly reduced α4β7 memory T-cell counts in PP and mLN representing populations within inflamed jejunal and colon tissues. Additionaly, an increased number of α4β7 memory T-cells was found in blood with targeted IC DATK32 compared to IP, suggesting T cells that have trafficked from blood to tissue can undergo reverse trafficking. Recent publications have reported a dose dependent increase in efficacy with systemically delivered anti-α4β7 despite full T-cell receptor occupancy in blood. Results of this study point to the potential for increased efficacy with high concentrations in local inflamed tissues. Although the mechanism of action is unclear, results suggest topically delivered anti-α4β7 may be an efficacious treatment in IBD.

Interleukin-7 receptor blockade by an anti-CD127 monoclonal antibody in nonhuman primate kidney transplantation.

IL-7 is an important cytokine for T cell lymphopoiesis. Blockade of the IL-7 signaling pathway has been shown to induce long-term graft survival or graft tolerance in murine transplant models through inhibiting T cell homeostasis and favoring immunoregulation. In this study, we assessed for the first time the effects of a blocking anti-human cluster of differentiation 127 (CD127) mAb administered in combination with low-dose tacrolimus or thymoglobulin in a life-sustaining kidney allograft model in baboons. Contrary to our expectation, the addition of an anti-CD127 mAb to the treatment protocols did not prolong graft survival compared to low-dose tacrolimus alone or thymoglobulin alone. Anti-CD127 mAb administration led to full CD127 receptor occupancy during the follow-up period. However, all treated animals lost their kidney graft between 1 week and 2 weeks after transplantation. Unlike in rodents, in nonhuman primates, anti-CD127 mAb treatment does not decrease the absolute numbers of lymphocyte and lymphocyte subsets and does not effectively inhibit postdepletional T cell proliferation and homeostasis, suggesting that IL-7 is not a limiting factor for T cell homeostasis in primates.

Abstract 4100: Receptor occupancy and neo-epitope specific T-cell repertoires in patients with solid tissue tumors following anti-PD-1 therapy

Abstract Background: In patients undergoing chemotherapy and/or immune therapy, endogenous T cells within the tumor micro-environment (TME) and in the periphery are subject to dynamic changes. Particularly, exhausted T cells in the TME and peripheral blood mononuclear cells (PBMCs) isolated from whole blood express the inhibitory receptor, Programmed Cell Death Receptor 1 (PD-1). A small but significant number of these T cells can recognize neo-epitopes (neoE) arising from patient specific mutations. We determined receptor occupancy (RO) in patients treated with monoclonal anti-PD-1 antibody AB122, which is currently in clinical development. Methods: Multi-color flow cytometry was used to determine RO post-AB122 administration using a directly-conjugated competitive antibody to AB122. In addition, we determined RO values using the established method for nivolumab using a biotinylated anti-human IgG4 to detect bound anti-PD-1. The assays were also optimized to determine RO in whole blood from patients with solid tumors treated with AB122. Receptor occupancy using both methods were compared. Further, whole exome sequencing from archival formalin-fixed, paraffin-embedded (FFPE) tissue was performed and T cells that recognized patient-specific neoE resulting from tumor-specific mutations were identified in patient blood. Results: In the dose-escalation study for AB122 monotherapy arm, a variety of dosing regimens have been evaluated, including Q2W, Q3W and Q4W. The number of doses received ranged from 1 to 20. Data from patients in the 80 and 240 mg Q2W cohorts showed that AB122 serum concentrations ≥1.5 μg/mL (equivalent to 10 nM) are associated with full receptor occupancy. The RO associated with AB122 dosing is maintained when dosed in combination with the potent A2aR/A2bR dual adenosine receptor antagonist AB928 in an ongoing clinical trial. Conclusions: Full RO is observed with both cohorts of AB122 monotherapy (80 and 240 mg Q2W) and in the 240 mg Q2W combination with AB928. Study of peripheral target engagement and expansion of neoE-specific T cell populations in a longitudinal study of solid tumor patients treated with AB122 could provide insight towards designing successful combination immune therapy regimens in future clinical trials with AB122. Citation Format: Devika Ashok, Songming Peng, Benjamin Yuen, Matt Walters, Stephen W. Young, Lisa Seitz. Receptor occupancy and neo-epitope specific T-cell repertoires in patients with solid tissue tumors following anti-PD-1 therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4100.

Assessment of Subcutaneous vs Intravenous Administration of Anti–PD-1 Antibody PF-06801591 in Patients With Advanced Solid Tumors

We assessed feasibility of monthly subcutaneous administration of PF-06801591, a humanized immunoglobulin G4 monoclonal antibody that binds to the programmed cell death (PD-1) receptor and blocks its interaction with PD-1 ligands. To evaluate the safety, efficacy, and pharmacokinetics of PF-06801591 administered intravenously vs subcutaneously. Ongoing phase 1, open-label, multicenter, dose-escalation study of 40 patients, 18 years or older, with locally advanced or metastatic solid tumors, enrolled between March 8, 2016, and March 5, 2018, from 4 US medical centers. An intravenous dose of 0.5, 1, 3, or 10 mg/kg of PF-06801591 was administered every 3 weeks or a subcutaneous dose of 300 mg was administered every 4 weeks. Dose escalation occurred after 2 to 4 patients were enrolled per dose level, with additional patients enrolled in each cohort for further assessment. The primary end points were dose-limiting toxic effects and safety. Secondary end points included pharmacokinetics, immunogenicity, PD-1 receptor occupancy, and efficacy. Of 40 enrolled patients (12 men and 28 women; mean [SD] age, 61 [13] years) in this phase 1 dose-escalation trial, 25 received PF-06801591 intravenously at escalating dose levels (0.5, 1, 3, or 10 mg/kg) and 15 patients received the monoclonal antibody subcutaneously at a single dose level. No dose-limiting toxic effects were observed. Grade 3 or higher treatment-related adverse events occurred in 4 (16%) patients treated intravenously and 1 (6.7%) patient treated subcutaneously. Immune-related adverse events occurred in 10 (40%) patients treated intravenously and 3 (20%) treated subcutaneously. No dose-adverse event associations were observed during intravenous dose escalation, and no serious skin toxic effects occurred with subcutaneous delivery. Responses were seen in 5 patients receiving PF-06801591 intravenously and in 2 patients treated subcutaneously for an overall objective response rate of 18.4%. Median overall survival was not reached with intravenous dosing vs 10.7 months with subcutaneous administration. Exposure to PF-06801591 increased in a dose-proportional manner over the range of intravenous doses. Median time to maximum observed serum concentration was 8 days after subcutaneous administration. Full PD-1 receptor occupancy was seen in all dose cohorts. Anti-PD-1 antibody PF-06801591 was tolerable and showed antitumor activity in a variety of tumor types across all dose levels of intravenous and subcutaneous administration. Monthly subcutaneous administration of PF-06801591 offers a convenient, effective alternative to currently available intravenously administered checkpoint inhibitors. ClinicalTrials.gov identifier: NCT02573259.

Anti-PD-1 antibody cetrelimab (JNJ-63723283) in patients with advanced cancers: Updated phase I/II study results.

31 Background: Cetrelimab (JNJ-63723283) is an IgG4, anti-programmed cell death protein-1 (PD-1) antibody. Here we present updated results from an ongoing phase 1/2 study of cetrelimab in patients (pts) with advanced or refractory solid cancers. Methods: Part 2 of the study evaluated safety and efficacy of cetrelimab at 240 mg Q2W, a recommended phase 2 dose selected in Part 1 (Calvo JCO 2018; 36 suppl 5:58). Tumor types for Part 2 included non-small cell lung cancer (NSCLC), melanoma (MEL), bladder, renal cell, small cell lung cancer (SCLC), microsatellite-high (MSI-H)/DNA mismatch repair deficient (dMMR; locally or centrally tested) colorectal cancer (CRC) and gastric/esophageal cancer (GCA/EC). Tumor response was assessed by the investigator following RECIST v1.1. Results: As of 3 Sep 2018, 192 pts have been treated with cetrelimab from 80–800 mg Q2W and 480 mg Q4W. Median age was 60 years (23–86), and median prior regimens was 2 (1–12). Median duration of treatment was 85 days (1–561); 82 pts remain on treatment. Full receptor occupancy was maintained throughout dosing interval. Most common adverse events (AEs) were asthenia (19%), fatigue (19%), dyspnea (16%) and diarrhea (16%). Grade ≥3 AEs, regardless of causality, were reported in 45% of pts; most common were anemia (6%), dyspnea (4%), increased ALT (3%) and increased AST (3%). Observed serious AEs were dyspnea (4%), pleural effusion and intestinal obstruction (3% each). All grade and grade ≥3 immune-related AEs were reported in 30% and 7% of pts, respectively. Among response-evaluable pts (n = 156) from Parts 1 and 2, overall response rate (ORR) was 15%, with 2 complete and 22 partial responses. Half of pts had stable disease or better. ORR was 26% (7/27) in NSCLC (42% [5/12] in PD-L1+ NSCLC [≥50% by IHC]), 25% (12/49) in MEL (28% [12/43] in non-uveal MEL), 50% (1/2) in renal cancer, 8% (2/26) in MSI-H/dMMR CRC (recruited later per amendment) and 14% (2/14) in GCA/EC. No responses were observed in bladder cancer (n = 4) or SCLC (n = 10). Conclusions: The safety profile and preliminary activity of cetrelimab in immune-sensitive advanced cancers is consistent with known PD-1 inhibitors. The study is ongoing and analysis by PD-L1 status will be reported later. Clinical trial information: NCT02908906.

A Clinical Study of Tomaralimab (OPN-305), a Toll-like Receptor 2 (TLR-2) Antibody, in Heavily Pre-Treated Transfusion Dependent Patients with Lower Risk Myelodysplastic Syndromes (MDS) That Have Received and Failed on Prior Hypomethylating Agent (HMA) Therapy

A Clinical Study of Tomaralimab (OPN-305), a Toll-like Receptor 2 (TLR-2) Antibody, in Heavily Pre-Treated Transfusion Dependent Patients with Lower Risk Myelodysplastic Syndromes (MDS) That Have Received and Failed on Prior Hypomethylating Agent (HMA) Therapy