Monotherapy Dose Research Articles

First-in-human phase 1 dose-escalation results with livmoniplimab, an antibody targeting the GARP:TGF-ß1 complex, as monotherapy and in combination with the anti-PD-1 antibody budigalimab in patients with advanced solid tumors.

Transforming growth factor (TGF)-ß1 is a pleiotropic cytokine that can promote tumor growth and suppress antitumor immune responses. Latent TGF-ß1 associates with glycoprotein-A repetition predominant (GARP) on the surface of regulatory T cells prior to its activation and release. Livmoniplimab is a monoclonal antibody (mAb) that binds the GARP:TGF-ß1 complex to inhibit activation and release of TGF-ß1. It is in clinical development in combination with budigalimab, an anti-programmed cell death protein 1 Fc-modified mAb. The first-in-human, phase 1, dose-escalation results are presented herein (ClinicalTrials.gov: NCT03821935). The dose-escalation phase enrolled adult patients with advanced solid tumors. Patients received escalating doses of livmoniplimab ranging from 3mg to 1500mg, once every 2 weeks (Q2W), as monotherapy or in combination with a 500mg fixed dose of budigalimab Q4W. The primary objective of the dose escalation was to determine the recommended phase 2 dose. Secondary objectives were to assess safety and pharmacokinetics (PK), and exploratory objectives included evaluating preliminary efficacy. Fifty-seven patients enrolled in the dose escalation: 23 in monotherapy cohorts and 34 in combination therapy cohorts. Dose-limiting toxicities were limited, no maximum tolerated dose was reached, and the maximum administered dose of 1500mg was selected for dose expansion. The most common adverse events reported in monotherapy-treated patients were fatigue, anemia, and nausea, and those in combination therapy-treated patients were pruritus, fatigue, nausea, and anemia. Livmoniplimab exhibited dose-proportional PK, and peripheral blood biomarker data demonstrated saturation of the GARP:TGF-ß1 complex on platelets at livmoniplimab doses within the linear PK range. No objective tumor responses were observed in the monotherapy dose escalation. However, the objective response rate was 15% in the combination dose escalation, with a median response duration of 8.4 months. Livmoniplimab was well-tolerated as monotherapy and in combination with budigalimab in the dose-escalation phase. Encouraging preliminary efficacy was demonstrated in the combination dose escalation in heavily pretreated patients, supporting further development of this novel drug combination in patients with advanced solid tumors.

One-year clinical outcome of aspirin-free prasugrel monotherapy following stent implantation in patients with chronic coronary syndrome: insight from ASET-JAPAN study

Abstract Background Single antiplatelet therapy with a potent P2Y12 inhibitor without aspirin after coronary stent implantation may provide an adequate balance between ischemic and bleeding risks in selected patients. The 3-month follow-up of the Acetyl-Salicylic Elimination Trial (ASET)-Japan pilot study demonstrated the feasibility and safety of Prasugrel monotherapy without aspirin after successful percutaneous coronary intervention (PCI) in selected patients with chronic coronary syndrome (CCS). Purpose The current study aimed to evaluate the 1-year clinical outcome in the ASET-Japan. Methods The ASET-Japan pilot study was designed to demonstrate the feasibility and safety of the approved dose of prasugrel monotherapy in Japan without aspirin after optimal PCI with a platinum-chromium everolimus-eluting stent in CCS population. After successful procedure, all patients were treated with a locally approved maintenance dose of 3.75 mg/day of Prasugrel monotherapy up to 3-month. After 3-month, the choice of antiplatelet therapy was left to the discretion of the investigators. Patients were followed up to 1 year. The target lesion-related endpoint was a composite of cardiac death, spontaneous target-vessel myocardial infarction (MI) >48 h after the index PCI or clinical-driven target lesion revascularisation. Patient-Oriented Composite Endpoint (POCE) was defined as a composite of all cause mortality, any stroke, any MI and any revascularisation. Spontaneous MI was defined according to Forth universal definition. The event rate was estimated by the Kaplan-Meier method. The event was adjudicated by an independent clinical event committee. Results A total of 208 patients were enrolled in the study. The average anatomical SYNTAX score was 7.96 (±4.6). After procedure, prasugrel monotherapy was immediately initiated. After 3-month, Prasugrel monotherapy was continued in 88.6% up to 1-year. Aspirin monotherapy was prescribed to 10 patients (5.0%), while 6 patients (3.0%) were on DAPT at 1-year. All-cause mortality rate was 1.49%, with no occurrence of cardiovascular death. Revascularisation occurred in 4.0% (n=8) with no occurrence of TLR, while one patient (0.5%) underwent a clinical driven target vessel revascularisation. In summary, 7 out of 8 revascularisations were non-target vessel revascularisation (6 clinically-driven non-TVR). Spontaneous non TV-MI occured in 0.5% (n=1) of patients. There was no definite/probable stent thrombosis up to 1 year. The target lesion related endpoint rate at 1-year was 0%, whereas 1-year POCE rate was 7.0% (n=14). Conclusion Discontinuation of Aspirin and Prasugrel monotherapy at a low maintenance dose of 3.75 mg/day following an angiographically successful stent deployment was feasible and safe in selected patients with CCS and low SYNTAX score. This safety profile is confirmed at 1 year while the investigators, in their large majority and at their own discretion, had maintained the prasugrel treatment.

Thirty days clinical outcomes following stent implantation with aspirin-free prasugrel monotherapy in non-ST segment elevation myocardial infarction. Interim report from ASET-Japan pilot study

Abstract Background Dual antiplatelet therapy with a P2Y12 inhibitor, in addition to aspirin, is the standard therapy after percutaneous coronary intervention (PCI) for non-ST-segment elevation acute coronary syndrome (NSTE-ACS) to prevent ischemic cardiovascular events. The Acetyl-Salicylic Elimination Trial (ASET) pilot studies conducted in Japan in patients with NSTE-ACS investigated the safety and feasibility of a low-dose prasugrel monotherapy after PCI. Purpose To ensure the safety of the patients, enrolment in the study was implemented only after confirmation of a successful procedure. The abstract reports our interim analysis, aimed at evaluating preliminary safety and feasibility. Methods The ASET-Japan pilot study was designed to explore the feasibility and safety of a low dose of prasugrel monotherapy (3.75mg/day), without adjunctive aspirin, after optimal PCI using Everolimus eluting stent (EES) in Japanese patients with non-ST-segment elevation acute coronary syndromes. The primary endpoint in the ASET-Japan NSTE-ACS (Phase 2) is a 12-month clinical outcome. The study is currently in the follow-up phase. All the target lesions were treated with a platinum-chromium everolimus-eluting stent. The primary ischemic endpoint was the composite of cardiac death, spontaneous target vessel myocardial infarction, or definite stent thrombosis, and the primary bleeding endpoint was Bleeding Academic Research Consortium types 3 and 5 bleeding up to 12-month. If more than 3 events occurred, trial enrollment would have to be terminated by the data and safety monitoring board. Results One hundred one patients were enrolled after successful index PCI and completed a 30 days follow-up. The mean age was 69.1±12.3 years and 75.2% was male. The mean anatomical SYNTAX score was 7.9±4.7. Unstable angina (UAP) and NSTEMI were seen in 24.8% (25/101) and 75.2% (75/101) patients, respectively. According to the Braunwald classification, 8 percent of the patients were categorised as Class IA UAP, 48% as Class IB, 20% as Class IIB, 4% as Class IIIA and 20% as Class IIIB. In NSTEMI patients, the median (IQR) pre-procedural troponin value (cardiac Troponin T or I) was 2.79 (1.12 – 22.27) times the Upper Limit of Normal. According to the PRECISE DAPT score, 36.6% of patients were categorised as High Bleeding Risk (HBR) with scores above 25. At one month, the primary ischemic endpoints of cardiac death, target-vessel spontaneous MI or definite Stent thrombosis did not occur. Two patients (2.0%) had BARC type 3a bleeding. Conclusion Prasugrel monotherapy in the first 30 days following platinum-chromium everolimus-eluting stent deployment is a feasible and safe strategy in NSTE-ACS patients with simple anatomy and successful PCI.

Subgroup results from KARDIA-2: impact of demographic and baseline disease characteristics on zilebesiran response in patients with hypertension uncontrolled by a standard oral antihypertensive

Abstract Background Zilebesiran is an investigational RNA interference therapeutic targeting hepatic angiotensinogen synthesis. In KARDIA-1, a single subcutaneous (SC) dose of zilebesiran monotherapy significantly reduced 24-hr mean ambulatory and office systolic blood pressure (SBP) from baseline to Months 3 and 6 versus placebo. The Phase 2 KARDIA-2 study assessed efficacy and safety of zilebesiran with a standard oral antihypertensive in patients with uncontrolled hypertension. Purpose Uncontrolled hypertension is a leading cause of cardiovascular morbidity and mortality, and medication non-adherence affects blood pressure control. Developing effective, long-lasting treatments is crucial for patients with hypertension uncontrolled by standard therapy. Methods KARDIA-2 enrolled adults with mild-to-moderate hypertension who were untreated or receiving stable therapy with ≤2 antihypertensives. Patients discontinued prior antihypertensive medication and were randomized 10:7:4 to open-label, once-daily oral treatment with 40 mg olmesartan, 5 mg amlodipine, or 2.5 mg indapamide. After ≥4 weeks on protocol-specified medication, patients with a 24-hr mean ambulatory SBP of 130–160 mmHg were randomized 1:1 in a double-blind manner to a single SC dose of zilebesiran 600 mg or placebo as add-on therapy. The primary endpoint was change from baseline to Month 3 in 24-hr mean ambulatory SBP versus placebo for each group. Efficacy and safety were also assessed in pre-specified subgroups: age (<65; ≥65 years), sex, race (Black; other), baseline 24-hr mean ambulatory SBP (<145; ≥145 mmHg), and baseline estimated glomerular filtration rate (≥60; <60 mL/min/1.73m2). Results The primary analysis included 667 patients (median age [range] 59 [27–75] years; 57% male, 28% Black). At Month 3, least-squares mean differences (LSMD) (95% confidence interval [CI]) between zilebesiran and placebo for the olmesartan, amlodipine, and indapamide groups were −4.0 (−7.6, −0.3), −9.7 (−12.9, −6.6), and −12.1 (−16.5, −7.6) mmHg, respectively, for 24-hr mean ambulatory SBP (all p<0.05). LSMD (95% CI) in office SBP for the same groups were −7.0 (−10.4, −3.6), −10.2 (−13.5, −6.9), and −18.5 (−22.8, −14.2) mmHg, respectively, (all p<0.001). SBP reductions were consistent across subgroups, except for a trend towards an attenuated response observed in Black patients (Figs 1, 2). More patients receiving zilebesiran (49–58%) than placebo (39–48%) experienced ≥1 adverse event through Month 6, with low rates of hyperkalaemia, hypotension, or acute kidney injury reported across all groups. Conclusion In KARDIA-2, a single dose of zilebesiran significantly reduced SBP versus placebo at Month 3 on top of a standard oral antihypertensive, with encouraging safety data. SBP reduction was consistent across most subgroups. Treatment with zilebesiran combined with standard antihypertensives may be effective for a broad population of patients with hypertension uncontrolled on monotherapy.

Comprehensive biomarker and modeling approach to support dose finding for BI 836880, a VEGF/Ang-2 inhibitor

BackgroundBI 836880 is a humanized bispecific nanobody® that binds to and blocks vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2). A comprehensive biomarker and modeling approach is presented here that supported dose finding for BI 836880.MethodsTwo Phase I dose-escalation studies (1336.1 [NCT02674152], 1336.6 [NCT02689505]) assessed BI 836880 in adults with confirmed locally advanced or metastatic solid tumors, refractory to standard therapy or for which standard therapy was not reliably effective. Two dosing schedules were investigated, 3 weeks (q3w) or once weekly (qw), starting at a dose of 40 mg. In a comprehensive biomarker approach, soluble pharmacodynamic markers (free and total plasma VEGF-A and Ang-2), as well as circulating angiogenic factors (soluble VEGF3, soluble Tie2 and placenta growth factor, amongst others) were analyzed to assess target engagement in peripheral blood for q3w doses. A Population based pharmacokinetics/pharmacodynamics (PopPK/PD) model was built using the limited Phase I dataset to support dose finding by simulations. In order to demonstrate drug activity in the tumor, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was applied.ResultsDCE-MRI scans supported target engagement in the tumor. Free VEGF-A was depleted at all doses, whereas free Ang-2 decreased dose-dependently, reaching depletion in most patients from 360 mg q3w onwards. While total VEGF-A levels increased in a dose-dependent manner, reaching saturation at 360 mg q3w, total Ang-2 levels increased, but did not plateau. Angiogenic biomarkers showed changes from doses ≥ 360 mg q3w. PopPK/PD modeling showed that doses ≥ 360 mg q3w led to > 90% inhibition of free Ang-2 at steady-state in most patients. By increasing the dose to ≥ 500 mg q3w, > 90% of patients are expected to achieve this level.ConclusionsThe comprehensive analyses of multiple target engagement markers support BI 836880 720 mg q3w as a biologically relevant monotherapy dose schedule.Trial registration: NCT02674152 and NCT02689505.

Pirtobrutinib, a highly selective, non-covalent (reversible) BTK inhibitor in patients with B-cell malignancies: analysis of the Richter transformation subgroup from the multicentre, open-label, phase 1/2 BRUIN study

Richter transformation usually presents as an aggressive diffuse large B-cell lymphoma, occurs in up to 10% of patients with chronic lymphocytic leukaemia, has no approved therapies, and is associated with a poor prognosis. Pirtobrutinib has shown promising efficacy and tolerability in patients with relapsed or refractory B-cell malignancies, including those who progress on covalent Bruton tyrosine kinase (BTK) inhibitors. This study aims to report the safety and activity of pirtobrutinib monotherapy in a subgroup of patients with Richter transformation from the multicentre, open-label, phase 1/2 BRUIN study. This analysis included adult patients (aged ≥18 years) with histologically confirmed Richter transformation, an Eastern Cooperative Oncology Group performance status score of 0-2, and no limit of previous therapies, with patients receiving first-line treatment added in a protocol amendment (version 9.0, Dec 15, 2021). Pirtobrutinib 200 mg was administered orally once a day in 28-day cycles. The primary endpoint of phase 1 of the BRUIN trial as a whole, which has been previously reported, was to establish the recommended phase 2 dose for pirtobrutinib monotherapy and the phase 2 primary endpoint was overall response rate. Safety and activity were measured in all patients who received at least one dose of pirtobrutinib monotherapy. This BRUIN phase 1/2 trial was registered with ClinicalTrials.gov and is closed to enrolment (NCT03740529). Between Dec 26, 2019, and July 22, 2022, 82 patients were enrolled, of whom five were enrolled during phase 1 and 77 during phase 2. All but one patient received a starting dose of 200 mg pirtobrutinib once a day as the recommended phase 2 dose. The remaining patient received 150 mg pirtobrutinib once a day, which was not escalated to 200 mg. The median age of patients was 67 years (IQR 59-72). 55 (67%) of 82 patients were male and 27 (33%) were female. Most patients were White (65 [79%] of 82). 74 (90%) of 82 patients received at least one previous Richter transformation-directed therapy. Most patients (61 [74%] of 82) had received previous covalent BTK inhibitor therapy for chronic lymphocytic leukaemia or Richter transformation. The overall response rate was 50·0% (95% CI 38·7-61·3). 11 (13%) of 82 patients had a complete response and 30 (37%) of 82 patients had a partial response. Eight patients with ongoing response electively discontinued pirtobrutinib to undergo stem-cell transplantation. The most common grade 3 or worse adverse event was neutropenia (n=19). There were no treatment-related deaths. Pirtobrutinib shows promising safety and activity among patients with Richter transformation, most of whom received previous Richter transformation-directed therapy, including covalent BTK inhibitors. These data suggest that further investigation is warranted of pirtobrutinib as a treatment option for patients with relapsed or refractory Richter transformation after treatment with a covalent BTK inhibitor. Loxo Oncology.

First-in-human study of AMG 193, an MTA-cooperative PRMT5 inhibitor, in patients with MTAP-deleted solid tumors: results from phase I dose exploration

Homozygous deletion of methylthioadenosine phosphorylase (MTAP) occurs in ∼10%-15% of solid tumors. AMG 193, a CNS-penetrant methylthioadenosine-cooperative protein arginine methyltransferase 5 (PRMT5) inhibitor, selectively induces synthetic lethality in MTAP-deleted tumor cells. Here, we report results of the completed monotherapy dose exploration evaluating AMG 193 in patients with MTAP-deleted solid tumors. In this first-in-human, multicenter, open-label, phase I study, patients with advanced CDKN2A-deleted and/or MTAP-deleted solid tumors received AMG 193 orally [once (o.d.) or twice (b.i.d.) daily] continuously in 28-day cycles. Primary objectives were safety and tolerability assessed by dose-limiting toxicities and determination of the maximum tolerated dose; secondary objectives included pharmacokinetics and preliminary antitumor activity measured by RECIST v1.1. As of 23 May 2024, 80 patients in dose exploration received AMG 193 at doses 40-1600 mg o.d. or 600 mg b.i.d. The most common treatment-related adverse events were nausea (48.8%), fatigue (31.3%), and vomiting (30.0%). Dose-limiting toxicities were reported in eight patients at doses ≥240 mg, including nausea, vomiting, fatigue, hypersensitivity reaction, and hypokalemia. The maximum tolerated dose was determined to be 1200 mg o.d. Mean exposure of AMG 193 increased in a dose-proportional manner from 40 mg to 1200 mg. Among the efficacy-assessable patients treated at the active and tolerable doses of 800 mg o.d., 1200 mg o.d., or 600 mg b.i.d. (n= 42), objective response rate was 21.4% (95% confidence interval 10.3% to 36.8%). Responses were observed across eight different tumor types, including squamous/non-squamous non-small-cell lung cancer, pancreatic adenocarcinoma, and biliary tract cancer. At doses ≥480 mg, complete intratumoral PRMT5 inhibition was confirmed in paired MTAP-deleted tumor biopsies, and molecular responses (circulating tumor DNA clearance) were observed. AMG 193 demonstrated a favorable safety profile without clinically significant myelosuppression. Encouraging antitumor activity across a variety of MTAP-deleted solid tumors was observed based on objective response rate and circulating tumor DNA clearance.

632P Results from the first-in-human study of ATR inhibitor, IMP9064 monotherapy dose escalation in patients with advanced solid tumors

632P Results from the first-in-human study of ATR inhibitor, IMP9064 monotherapy dose escalation in patients with advanced solid tumors

Efficacy and Safety of Salvage-line Nivolumab Monotherapy for Advanced Esophageal Squamous Cell Carcinoma: Comparison of 240 mg Versus 480 mg Doses

BackgroundNivolumab monotherapy is the standard second-line treatment for advanced esophageal squamous cell carcinoma (ESCC) after failure of platinum-based chemotherapy without anti-PD-1 antibody. Fixed dosing with 240 mg every 2 weeks was approved initially, followed by fixed dosing with 480 mg every 4 weeks based on pharmacokinetics data. However, information on the comparative efficacy and safety of the two doses remains limited.MethodsWe compared progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and the incidence of adverse events (AEs) between the two doses in 117 patients who received second-line (n = 85) or later-line (n = 32) nivolumab monotherapy at our institution between January 2016 and December 2021.ResultsIn the second-line group, patient characteristics for the 240 mg and 480 mg groups were as follows (240 mg vs. 480 mg): performance status (PS) 0/1/2 was 34/61/5% vs. 54/42/4%, and prior fluoropyrimidine plus platinum therapy (FP) was 81.3% vs. 42.3%. In the later-line group, the characteristics were: PS 0/1/2 was 28/60/12% vs. 14/86/0%, and prior FP was 60.0% vs. 42.8%. ORR was 11.9 vs. 24.0% in the second-line group (p = 0.19) and 0 vs. 14.3% in the later-line group (p = 0.22). Median PFS was 1.7 vs. 4.1 months on second-line (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.35–1.01, p = 0.056) and 1.4 vs. 1.8 months on later-line (HR 0.58, 95% CI 0.23–1.46, p = 0.25); AEs of any grade were observed in 58.3 vs. 69.7%, respectively.ConclusionsThe efficacy and safety of the two doses of nivolumab monotherapy were comparable in patients with advanced ESCC.

A phase 1/1b study of the IL-2 prodrug WTX-124 in patients with locally advanced or metastatic solid tumors after checkpoint inhibitor therapy: Initial results of the combination dose escalation with pembrolizumab.

2623 Background: High dose IL-2 can produce durable remissions in patients who have progressed on checkpoint inhibitors but is infrequently used due to its life-threatening toxicities such as vascular leak syndrome (VLS). WTX-124 is a half-life extended, masked cytokine (INDUKINE molecule) rationally engineered to release wild type IL-2 in tumors. We previously reported that WTX-124 is clinically active as a monotherapy at doses safely administered in the outpatient setting. Here we update the data and present initial results from the combination dose escalation with pembrolizumab (anti-PD-1; NCT05479812). Methods: In this first-in-human trial, WTX-124 is administered IV Q2W alone or with pembrolizumab 400 mg IV Q6W. Eligible patients are adults with relapsed/refractory solid tumors who have previously received standard of care checkpoint inhibitor regimens. Primary endpoints are safety and ORR; secondary endpoints are PK, PD, immunogenicity, and PFS/OS. The dose escalation is guided by a mTPI-2 study design. Results: As of January 29, 2024, 32 patients have been treated with WTX-124 in five monotherapy dose escalation cohorts (1-18 mg; N=24) and two combination cohorts (3-6 mg; N=8). The most common AEs related to WTX-124 monotherapy were arthralgias, myalgias, fatigue and pruritis. Of ten evaluable patients treated with 12 or 18 mg WTX-124 monotherapy, three had objective responses, including a confirmed CR in a patient with cutaneous squamous cell cancer and unconfirmed PRs in patients with melanoma and gastroesophageal junction cancer. On-treatment tumor biopsies showed evidence of increased lymphocyte activation and PD-L1 expression. Addition of pembrolizumab to 3-6mg WTX-124 did not change the character of AEs observed with WTX-124 monotherapy. Related AEs occurred more frequently for the combination than for 3-6mg WTX-124 monotherapy, but all were mild to moderate in severity (Gr1: 74.2%, Gr2: 25.8%) and there was no increase in the percentage of Gr2 events. No DLTs, related serious AEs, treatment discontinuations due to related toxicities, or occurrences of VLS have been observed in any patient treated to date with either WTX-124 or WTX-124/pembrolizumab. Pembrolizumab did not affect WTX-124 or IL-2 PK. WTX-124 has been escalated to 12 mg IV Q2W, the initial monotherapy dose that produced objective responses, in combination with pembrolizumab. Conclusions: WTX-124 administered as a monotherapy IV Q2W in the outpatient setting is well tolerated and clinically active in patients with relapsed/refractory solid tumors after checkpoint inhibitor therapy. Preliminary results from the ongoing combination dose escalation with pembrolizumab show no new safety signals. Updated data on safety, biomarkers, and preliminary clinical activity for the combination will be presented. Clinical trial information: NCT05479812 .

Dose optimization and exposure-response analyses to support optimal dose of ABBV-400, a novel C-met–targeting antibody drug conjugate, in patients with metastatic colorectal cancer (mCRC).

3030 Background: ABBV-400 is an antibody drug conjugate (ADC) consisting of a c-Met targeting antibody conjugated to a potent inhibitor of topoisomerase 1 (Top1) payload. ABBV-400 has shown encouraging activity and demonstrated tolerability of dosages up to 3.0 mg/kg Q3W as monotherapy in patients with advanced solid tumors in an ongoing phase 1 study (1). Dosage optimization is a critical aspect of oncology drug development and FDA Project Optimus has focused on reformulating the dosage selection paradigm for oncology products. The phase 1 study included a dose optimization phase in mCRC patients in which 3 doses were evaluated (1.6, 2.4 and 3.0 mg/kg Q3W) to determine the optimal dose for further development. Herein, exposure-response analyses are reported to determine optimal monotherapy dose in mCRC patients. Methods: Data across a range of doses (1.6 – 6.0 mg/kg Q3W) from the phase 1 study (NCT05029882) were used. Population pharmacokinetics (PK) and exposure-response (E-R) analyses were conducted to characterize ABBV-400 conjugate and unconjugated payload PK and the relationship between exposures and efficacy (objective response rate [ORR]) and safety (Grade (Gr) ≥ 3 neutropenia, anemia and thrombocytopenia) endpoints. Relative dose intensity (RDI) analysis was performed. Results: ABBV-400 conjugate and payload PK were adequately described by a combined multi-analyte population PK model with first order kinetics (n=204). ABBV-400 conjugate average concentration was a better predictor of response and showed that higher exposure correlated with higher probability of response (n=122 CRC, ORR, p < 0.05) and safety events (n=204, Gr ≥ 3 neutropenia, anemia and thrombocytopenia, p < 0.001). Dose intensity analyses showed greater number of dose reductions for 3 mg/kg Q3W with effective (actual) dose received of 2.6 mg/kg Q3W in mCRC patients. E-R analyses for safety and efficacy and dose intensity analyses in mCRC 3L+ patients indicate that both 2.4 and 3.0 mg/kg doses provided meaningful efficacy (ORR); while the 3.0 mg/kg dose may provide higher response rates, the 2.4 mg/kg Q3W dosing regimen provides an optimal balance of safety and efficacy compared to 3.0 mg/kg Q3W. Conclusions: Population PK, E-R for efficacy and safety and RDI analyses and totality of clinical data supported the selection of 2.4 mg/kg Q3W as optimal ABBV-400 monotherapy dose for further study in mCRC patients. 1. Sharma M, et al. ASCO 2023. Abstract 3015. Clinical trial information: NCT05029882 .

Correlative biomarker analyses for optimal therapeutic dose determination of ABBV-383, a B-cell maturation antigen (BCMA) x CD3 bispecific antibody, in patients with relapsed/refractory multiple myeloma (RRMM).

7532 Background: ABBV-383 is a BCMA x CD3 bispecific antibody with 2 high-affinity BCMA-binding domains and a low-affinity CD3 engaging arm that has been shown to decrease the negative impact of soluble BCMA (sBCMA) and drive sustained T-cell activation with reduced cytokine release in preclinical models of MM. Here, we describe correlative biomarker results of baseline and longitudinal sBCMA levels and immune profiles in the ongoing first-in-human trial that supports 60 mg Q4W as the optimal therapeutic dose of ABBV-383 monotherapy. Methods: Peripheral blood and serum samples from patients with RRMM enrolled in the phase 1 open-label, dose-expansion study (NCT03933735) who received ABBV-383 at 20, 40, or 60 mg Q3W or 60 mg Q4W were collected at baseline (post-dexamethasone, pre–ABBV-383), on treatment, and at disease progression. Samples were analyzed by flow cytometry for immune cell populations, Luminex for cytokines, and electrochemiluminescence ligand binding for sBCMA. Results: Median sBCMA levels at baseline were highly variable among patients, but did not associate with clinical response (≥ partial response [PR]) to ABBV-383 at the selected optimal dose level of 60 mg Q4W (<PR: 244.7 ng/mL; ≥PR: 52.2 ng/mL; P=0.13). Reduction in sBCMA levels over time associated with clinical response (Cmin at cycle 5: <PR, 244.7 ng/mL; ≥PR, 4.7 ng/mL; P=0.04). ABBV-383 treatment led to a rapid and transient increase of proinflammatory cytokines, including IL-6, IL-8, IL-10, TNF-α (Cmax within cycle 1: 29, 349.5, 1375, 456.5 pg/mL, respectively), and promoted T-cell redistribution (89% reduction of CD8+ T cells from periphery), activation (1.9-fold increase in CD69+CD8+ T cells), and proliferation (2-fold increase in Ki67+CD8+ T cells) within cycle 1 in 60-mg Q4W-treated patients. The frequency of baseline CD8+ T-cell exhaustion (PD-1/TIM3) did not impact clinical response at the optimal dose level of 60 mg Q4W ABBV-383 (<PR: 3.5%; ≥PR: 3.9%; P=0.9). Peak induction levels of proinflammatory cytokines during cycle 1 correlated with occurrence of cytokine release syndrome (≥G1) as well as clinical response across dose levels. Conclusions: High-avidity BCMA binding coupled to low-affinity T-cell engagement distinguishes the resulting mechanism of action for ABBV-383. Responses to 60 mg Q4W ABBV-383 were independent of baseline sBCMA levels and resulted in rapid and transient proinflammatory cytokine production that promoted robust T-cell redistribution, activation, and proliferation, indicating that the optimal dose of ABBV-383 maximizes its clinical potential as a convenient, safe, and effective therapy for MM. Clinical trial information: NCT03933735 .

A phase 1 dose-escalation and expansion study of CUE-101, given as monotherapy and in combination with pembrolizumab, in patients with recurrent/metastatic HPV16+ head and neck squamous cell cancer (R/M HNSCC).

6004 Background: Immuno-STATs are modular T cell engagers engineered to selectively activate tumor-antigen specific CD8+ T cells via targeted delivery of cytokines. CUE-101, the first Immuno-STAT in clinical trials, is composed of a human leukocyte antigen (HLA) complex, HLA-A*0201, a peptide epitope derived from the HPV16 E7 protein and 4 molecules of attenuated human interleukin-2 (IL-2), to bind, expand, and activate HPV16-specific CD8+ T cells for the treatment of HPV16+ HNSCC. Methods: CUE-101-01 is an ongoing first-in-human study in HLA-A*0201 patients with HPV16+ R/M HNSCC. Escalating doses of CUE-101 monotherapy (0.06 mg/kg to 8 mg/kg) were evaluated in R/M HNSCC refractory to ≥ 1 platinum or checkpoint inhibitor (CPI) based therapy, alone or combined with pembrolizumab (1 mg/kg to 4 mg/kg + 200 mg pembrolizumab) in the first line treatment of PD-L1+ R/M HNSCCs. Enrollment at the recommended phase 2 dose (RP2D) was expanded. Therapy was administered every 3 weeks (Q3W) until disease progression or intolerable toxicity. Safety, PK/PD, and antitumor activity were assessed. Results: Enrollment in both monotherapy and combination cohorts is now completed (N=80 patients, 49 in monotherapy and 31 CUE-101 plus pembrolizumab). Following dose escalation, 4 mg/kg Q3W of CUE-101 was selected for RP2D for both monotherapy and pembrolizumab combination cohorts. At data cut-off, adverse events (AEs) have been manageable and 92% grade ≤2. The most frequent grade 3 AEs reported include lymphocyte count decreased (7.6%), anemia (6.3%), decreased appetite (5.1%) and infusion-related reactions (5.1%). In combination with pembrolizumab no unanticipated significant safety concerns have emerged. Exposure-dependent PD effects of CUE-101 are consistent with IL-2 pharmacology and indicate preferential expansion of CUE-101 on E7-specific T cells. Among the 19 evaluable patients treated with the RP2D of CUE-101 plus pembrolizumab, an ORR of 47% (1 CR, 8 PRs), a Disease Control Rate (ORR + durable SDs) of 74%, and mPFS of 5.8 months [95% CI 2.56; NA] were observed. A median OS has not been reached. Of the 9 patients with confirmed objective responses, all achieved >99% reduction in HPV16 cfDNA in plasma during their treatment course. Among the 19 evaluable monotherapy RP2D patients, 1 PR and 6 durable SD (SD ≥ 12 weeks) and mOS of 20.8 months [95% CI 11.0; NA] were observed. Conclusions: An ORR of 47% and a mPFS of 5.8 months were observed in R/M HNSCC patients treated with CUE-101 4 mg/kg + pembrolizumab as 1L therapy. A median OS of 20.8 was observed in patients treated with CUE-101 monotherapy as post-platinum/CPI therapy. CUE-101 continues to demonstrate safety, tolerability and meaningful clinical benefit in patients with HPV16+ R/M HNSCC. Clinical trial information: NCT03978689 .

Belzutifan plus lenvatinib (len) for Chinese patients (pts) with previously treated advanced clear cell renal cell carcinoma (ccRCC): Preliminary results of cohort 1 of the phase 1 LITESPARK-010 study.

4537 Background: Belzutifan, a first-in-class HIF-2α inhibitor, alone or in combination with a VEGFR-TKI, has shown durable antitumor activity in first- and subsequent-line settings of advanced ccRCC. LITESPARK-010 (NCT05030506) is a phase 1, 2-cohort, open-label study of belzutifan + len, with or without pembrolizumab, in Chinese pts with advanced ccRCC. We present preliminary results cohort 1. Methods: Chinese adults with histologically confirmed ccRCC who had 1-3 prior treatment regimens received belzutifan 120 mg PO QD for 3 wk followed by belzutifan 120 mg + len 20 mg PO QD until intolerable toxicity, disease progression, or pt withdrawal. The study included a dose-limiting toxicity (DLT) phase of 21 days after the start of combination treatment. Dual primary end points were safety and PK. Secondary end points included ORR, DOR, and PFS per RECIST v1.1 by investigator assessment and OS. Results: As of August 29, 2023, 24 pts were enrolled in cohort 1 and 23 received combination treatment; 1 pt discontinued in the monotherapy period because of treatment with non-study anti-cancer therapy. Median age was 61 years, 17 pts (71%) were male, and 14 (58%) had intermediate/poor IMDC risk. 14 pts (58%) received 1 prior line of therapy and 10 (42%) received ≥2 prior lines. Five pts (21%) received prior therapy with a PD-(L)1 inhibitor. As of the data cutoff date, 11 pts (46%) remained on treatment. Median follow up was 14.4 mo (range, 1.6-22.1). Ten pts were evaluated in the DLT phase, and 1 experienced a DLT (grade 2 treatment-related transient ischemic attack). All 24 pts (100%) experienced a treatment-related AE (TRAE) of any grade, most commonly anemia (100%) and proteinuria (88%). Grade 3 or 4 TRAEs occurred in 17 pts (71%), most commonly anemia (29%) and hypertension (29%). One pt (4%) experienced grade 3 hypoxia. No pts died (grade 5) due to a TRAE. After a single dose of belzutifan monotherapy, median Tmax was 1.8 h (range, 0.6-8.0), geometric mean AUC0-24 was 22,400 h·ng/mL (90% CI, 19,600-25,500), and geometric mean Cmax was 1640 ng/mL (90% CI, 1490-1820). Steady-state concentration was reached after 14 days of belzutifan monotherapy treatment; the accumulation ratio of AUC0-24 was 1.7 (90% CI, 1.5-1.9). Belzutifan + len treatment had similar PK to belzutifan monotherapy. In all 24 pts, confirmed ORR was 50% (95% CI, 29-71; all PRs). Median DOR was not reached (NR; range, 3.5-20.4+ months); 50% of responders remained in response for ≥12 mo per Kaplan-Meir estimate. Median PFS was 13.7 mo (95% CI, 8-NR) and median OS was NR (95% CI, NR-NR). The 12-mo PFS and OS rates were 57% and 75%, respectively. Conclusions: Preliminary data from the belzutifan + len showed promising antitumor activity in Chinese pts with previously treated ccRCC. The safety of belzutifan 120 mg + len 20 mg was consistent with the safety profiles of the individual drugs. Clinical trial information: NCT05030506 .

Covalent-103: A phase 1, open-label, dose-escalation and expansion study of BMF-500, an oral covalent FLT3 inhibitor, in adults with acute leukemia (AL).

TPS6589 Background: FLT3 mutations occur in 25-35% of AML and result from an internal tandem duplication (ITD) of amino acids in the juxtamembrane domain of FLT3 kinase or point mutations in the tyrosine kinase domain (TKD). FLT3-ITD mutations are associated with increased relapse, shorter remission, and decreased disease-free and overall survival. BMF-500 is a novel oral, highly potent and selective covalent inhibitor of FLT3 including wild-type (WT), ITD, TKD, and resistance mutations (e.g., gatekeeper F691). BMF-500 has high affinity for FLT3, lack of cKIT inhibition, and sustained cell-killing despite drug washout (Law et al., ASH 2022 Abst 2756). BMF-500 shows sustained tumor regression and improved survival in subcutaneous and disseminated xenografts of FLT3-m AML. Methods: COVALENT-103 (NCT05918692) is a multicenter, first-in-human study evaluating the safety, tolerability, and antileukemic activity of escalating doses of daily BMF-500 in patients with relapsed or refractory (R/R) AL, including AML, ALL, or MPAL, with or without FLT3-m. The trial has 2 arms that dose escalate in parallel: Arm A (without) and Arm B (with) concomitant use of a CYP3A4 inhibitor. Using an accelerated titration design (ATD), doses of BMF-500 are escalated in single-subject cohorts until one subject experiences ≥Grade 2 related adverse event or dose-limiting toxicity (DLT). At that point, the cohort will switch to a classical “3 +3” design. Patients with WT FLT3 AL may enroll up to 33% per arm. Treatment continues in 28-day cycles until progression or intolerability. Expansion cohorts will enroll additional patients to obtain further safety and efficacy data. Patients must be refractory, relapsed or have progressed on or following discontinuation of the most recent anti-cancer therapy or be ineligible for any approved standard of care, including hematopoietic stem cell transplant (HSCT). FLT3-positive AML patients must have received a FLT3 inhibitor approved for R/R FLT3-m AML. Additional inclusion criteria include ECOG PS ≤2, adequate organ function, and documented FLT3 mutation status. Key exclusion criteria include known CNS disease, clinically significant cardiovascular disease, and WBC >50,000/µL (uncontrollable with cytoreductive therapy). The primary objective is to evaluate safety and tolerability and determine the optimal biological dose (OBD)/ recommended Phase 2 dose (RP2D) of BMF-500 monotherapy based on available pharmacokinetic/pharmacodynamic (PK/PD), safety and efficacy data. Secondary objectives include characterization of the PK/PD of BMF-500, and assessment of its antitumor activity per modified Cheson (2003) criteria or NCCN Clinical Practice Guidelines (ALL Version 1.2022) as determined by the investigator. The study was initiated in July 2023, is currently in dose escalation, and we plan to enroll approximately 110 patients total. Clinical trial information: NCT05918692 .

A phase 1 study evaluating the safety, pharmacokinetics, and efficacy of fadraciclib, an oral CDK2/9 inhibitor, in patients with advanced solid tumors and lymphoma.

3125 Background: Fadraciclib (formerly CYC065)is a highly selective inhibitor of CDK2 (IC50= 5 nM) and CDK9 (IC50=26 nM) causing mitotic catastrophe and apoptotic death of cancer cells at sub-micromolar concentrations. In a previous Phase 1 study of intravenous fadraciclib monotherapy, a heavily pretreated endometrial cancer patient with CDNK2A, CDKN2B and PRMT5 loss achieved confirmed CR. This is the first study to evaluate oral fadraciclib monotherapy. Methods: A global Phase 1/2, open-label, dose-escalation study in subjects with advanced solid tumors or lymphoma (NCT04983810). The Phase 1 portion is exploring both schedule and dose of oral fadraciclib monotherapy in 28-day cycles to identify MTD and/or RP2D using a standard 3+3 design. Results: As of January 31, 2024, 45 subjects have received fadraciclib at 8 dose levels (DL1-6a: 50-150 mg, bid given 3-5 days per week for 3-4 out of 4 weeks or DL6b: 125 mg, daily for 4/4 weeks). Heavily pretreated patients with breast, colorectal, gynecological cancers, and T cell lymphoma with ECOG PS 0:1 (9:36) were enrolled. Fadraciclib was well tolerated at dose levels 1 to 5 (up to 100 mg bid). Adverse events reported were nausea (n=31), vomiting (n=23), thrombocytopenia (n=6). Grade 3 DLT of hyperglycemia (1/2 DL6 and 2/6 DL6a) and nausea (1/2 DL6) was observed at doses above 125mg bid M-F, 4/4 weeks. Hyperglycemia was controlled after dose interruption and blood glucose levels returned to normal range after treatment. Preliminary PK analysis suggests dose dependent exposure. At DL5 and above, plasma concentration was above target concentration from CDK2 and CDK9 target engagement studies. Preliminary PD analysis of treated patient samples showed suppression of expression in multiple target genes, including MYC, MCL1, CCNE/cyclin E, CDKN2A, CDKN2B, and PRMT5. Preliminary efficacy data are available for 31 evaluable patients. Two PRs after the first cycle were observed in one patient with CTCL and one with angioimmunoblastic T-Cell Lymphoma (AITL). Twenty patients showed SD. Tumor size reduction was observed in 10 patients. A squamous NSCLC patient harboring a CDK2NB loss of function mutation and prior chemo- and immunotherapy achieved reduction of 22% in the sum of all target lesions after 1 cycle of treatment. Conclusions: Based on data from the CYC065-101 study, fadraciclib appears well tolerated from DL1 to 5. The MTD for the bid dosing schedule is 100mg bid, M-F, 4/4 weeks. The trial is ongoing with evaluation of a daily dosing schedule. Clinical trial information: NCT04983810 .

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 .

BLU-222, an investigational, oral, potent, and highly selective CDK2 inhibitor (CDK2i), as monotherapy in patients (pts) with advanced solid tumors and in combination with ribociclib (RIBO) and fulvestrant (FUL) in HR+/HER2− breast cancer (BC).

1056 Background: CDK2 is implicated in CDK4/6 inhibitor (CDK4/6i) resistance in hormone receptor-positive/human epidermal growth factor receptor-2–negative (HR+/HER2−) BC. In addition, amplification and overexpression of cyclin E1 gene ( CCNE1), which leads to hyperactivation of cyclin E/CDK2 and CDK2 dependence, is associated with shorter survival in multiple aggressive cancers. CDK2 inhibition is thus an attractive novel anticancer approach. BLU-222 is an investigational, oral, potent, selective CDK2i in clinical development showing promise as a monotherapy and combination therapy. Methods: VELA (NCT05252416) is an international, open-label, phase 1/2 study evaluating BLU-222 safety and efficacy through dose escalation following a Bayesian Optimal Interval design. BLU-222 BID was administered in continuous 28-day cycles as monotherapy or in combination with RIBO + FUL. In monotherapy cohorts, pts with advanced relapsed/recurrent cancer were enrolled regardless of CCNE1 status. A combination cohort enrolled pts with HR+/ HER2− BC whose disease had progressed after treatment with a CDK4/6i. Results: As of January 22, 2024, 64 pts were included in the safety population: 53 in monotherapy cohorts (50-800 mg BID), 11 in the combination cohort (100-200 mg BID + 400 mg RIBO + 500 mg FUL). Median age was 63 y (range, 21-85); 88% were female. Most frequent cancer types in monotherapy cohorts were BC (32%, 17/53), ovarian (21%, 11/53), endometrial (8%, 4/53), and uterine (8%, 4/53). Pts had a median of 5 prior lines of therapy (LoT). Maximum tolerated dose had not been reached as of the data cutoff. With monotherapy, the most common treatment-emergent adverse events (TEAEs; ≥15%) included gastrointestinal events (nausea, diarrhea, vomiting), fatigue, anemia, photophobia, and hypokalemia. Dose-limiting toxicities occurred in 2 pts, 1 with grade 3 nausea at 800 mg BID and 1 with grade 3 blurred vision/photophobia at 600 mg BID; both improved after dose reduction. Increasing doses of BLU-222 monotherapy were associated with decreased TK1 activity and pRb. Eleven HR+/HER2− BC pts with a median of 5 prior LoT received BLU-222 with RIBO + FUL but have limited follow-up. The initial cohort of BLU-222 with RIBO + FUL was well tolerated. Updated combination data will be presented at the meeting. Conclusions: BLU-222 monotherapy was generally well tolerated in unselected heavily pretreated pts. In addition to encouraging safety, markers of cell cycle modulation and antitumor activity were seen. The initial cohort of BLU-222 with RIBO + FUL exhibited no additional safety concerns. Together, these data demonstrate the clinical potential of BLU-222 in CDK2-vulnerable tumors. Enrollment is ongoing for dose escalation and optimization. Clinical trial information: NCT05252416 .

Role of Vitamin C Supplementation in the Prevention of Premature Rupture of Membranes (PROM) and Preterm PROM: A Systematic Review and Meta-Analysis.

Vitamin C is a micronutrient assumed to have effects on the occurrence of "preterm premature rupture of membranes" (PPROM) and "premature rupture of membranes" (PROM). The objective of this review was to find the pooled incidence of PROM and/or PPROM between subgroups in relation to dose, mode of therapy (monotherapy vs. combination therapy) and history of PROM/PPROM in previous pregnancies. A search was conducted in the electronic databases (PubMed, Google Scholar, Scopus) from inception to November2022, using the search terms "Vitamin C", "Ascorbic acid", "preterm premature rupture of membrane" and "premature rupture of membrane". The lists of references of all the selected eligible articles were also searched to find studies of interest. A total of nine randomized controlled trials (published in English) with 16,076 participants involving the supplementation of vitamin C during pregnancywere picked up for analysis. Data management was done using the Review Manager (RevMan 5.3). A statistical test for publication bias was done in jamovi, version 2.3.18. In comparison to placebo, vitamin C supplementation was not found to be significantly effective in preventing the occurrence of PPROM/PROM. However, a low dose of vitamin Cand the monotherapy mode of administration significantly decreased the occurrence of PPROM/PROM. Vitamin C has significant beneficial effects in women with a history of PROM in a previous pregnancy. Hence, we conclude that vitamin C administered as monotherapy in low doses (preferably 100 mg/day) has definite benefits in preventing the occurrence of PROM/PPROM with greater advantages seen in those with a history of similar complications in a previous pregnancy.

A phase I/II, open-label, multicenter study to evaluate the safety, pharmacokinetics, pharmacodynamics, and efficacy of HB0036 in patients with advanced solid tumors.

e14504 Background: HB0036 is a bispecific IgG1 antibody targeting both human programmed death ligand 1 (PD-L1) and the T cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT). Here we report the initial results from the first-in human study ofHB0036 in patients with advanced malignancies. Methods: This is a first-in-human, phase I/II, multicenter, dose escalation and dose expansion study of HB0036 administered intravenously to adult pts with resistant/ refractory advanced or metastatic solid tumors who had failed standard therapies. Monotherapy of HB0036 will be conducted in 72 enrolled subjects. In the dose escalation phase (phase I), an accelerated titration followed by a 3+3 design was used to dose escalation by assessing the safety and tolerability of HB0036 monotherapy (dose range 0.04 mg/kg to 30 mg/kg), and determine the maximum tolerated dose (MTD). HB0036 was administered Q3w on a 21-day treatment cycle and dose-limiting toxicity (DLT) was observed in first treatment cycle. Tumor assessments per RECIST v1.1 were performed once every 6 weeks (2 cycles). HB0036 PK and PD analyses were performed. Results: At cutoff date of Jan 2, 2024, 19 pts (11 females and 8 males; ECOG 0/1, 3/16) with advanced refractory solid tumors have been enrolled in phase I (0.04 mg/kg [n = 1], 0.12 mg/kg [n = 1], 0.36 mg/kg [n = 1], 1 mg/kg [n = 3], 3 mg/kg [n = 3], 6 mg/kg [n = 3], 10 mg/kg [n = 4], 20 mg/kg [n = 3]). The median age was 59 (range 29-80) years. The pts were heavily pretreated with a median of 2 (range 1-4) prior lines of therapy. No DLT was observed. 13 (68.4%) pts experienced treatment-related adverse events (TRAEs), with 1 pt (5.3%) experienced grade ≥3 TRAEs. No grade 5 TRAE occurred. The incidence or severity of AE was not associated with the dose. The most common TRAEs (≥10%) were blood bilirubin increased, anemia, infusion-related reaction, AST elevated, ALT elevated, bilirubin conjugated increased, fever, hypertriglyceridemia, hypoalbuminemia, hypothyroidism and pyrexia. No SAEs related to HB0036 have been reported. As of DEC 25,2023, in 13 pts who had undergone at least 1 post-baseline tumor assessment, the investigator-assessed best response included 9 SDs and 4 PDs. The DCR was 69% (9/14, 95% CI, 38.6%-90.9%). Durable clinical benefit (SD for > 36 weeks) was seen in 1 subject (3 mg/kg) with lung sarcomatoid carcinoma. HB0036 has presented safe and well-tolerated profile up to doses of 20 mg/kg. To date, 5 responders are still on treatment. The dose escalation is still in progress. Conclusions: HB0036 showed an acceptable safety profile and promising anti-tumor activity in advanced solid tumors, which supports further studies to explore the safety and efficacy of HB0036 as a monotherapy and combination with other anti-tumor agents. Based on these data, phase II monotherapy and combination studies are in preparation. Clinical trial information: NCT05417321 .