Advanced Solid Tumors Research Articles

Exploring the safety and efficacy of GT201 as a first-in-class autologous tumor-infiltrating lymphocyte monotherapy in advanced solid tumors.

2547 Background: GT201, featuring a membrane bound IL-15 stably expressed on tumor-infiltrating lymphocytes (TIL), aims to augment TIL persistence and function as well as ameliorate immune suppression within the tumor microenvironment, offering potential for durable responses in advanced solid tumor patients. We present data from 7 patients enrolled in an open-label, single-arm, multicenter clinical study (NCT05729399), investigating the safety profile and efficiency trend of GT201 therapy. Methods: The GT201 phase 1 trial is designed with the primary endpoint of DLT evaluation and the secondary endpoint of measuring preliminary efficacy parameters including overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), duration of response (DOR, and overall survival (OS) following the RECIST v1.1. Results: As of January 22, 2024, a cohort of 7 pts has been enrolled in the study, with a median age of 48 and a median of 3 prior lines of therapy. Among these patients, 1 pt has a history of bone metastases, 2 pts have a history of liver metastases, and 1 pt has a history of brain metastases. Following the standard FC lymphodepletion, pts underwent infusion with GT201 at doses ≥ 5x109 total viable cells. Five pts subsequently received IL-2 as part of the treatment protocol. Treatment-related AEs were observed in ≥ 50% of pts with no grade≥3 AEs. Grade ≥ 3 AEs related to FC lymphodepleting chemotherapy and IL-2 included decreased lymphocyte count, decreased neutrophil count, and decreased white blood cell count, pyrexia and increased heart rate. Notably, all grade ≥3 AEs were either recovered or downgraded to grade ≤ 2 within 14 days. Among the 7 response-evaluable patients across various indications, including Non-Small-Cell-Lung Cancer (NSCLC), melanoma malignant, cervical cancer, and ovarian cancer, 3 patients (42.9%) achieved a confirmed partial response (PR), and 2 patients (28.6%) demonstrated stable disease (SD) as their best response. Notably, among the NSCLC subgroup, disease control (SD ≥ 24 weeks or any PR) was observed in all 3 pts (3/3, 100 %). GT201 cells can be detected in all patients receiving treatment, indicated by both staining IL15RA protein on peripheral T cells and measuring the transgene copy number in peripheral white blood cells. GT201 cells expanded robustly in patients and persist in peripheral blood beyond at least 6 months post cell infusion. Conclusions: In patients with heavily pretreated advanced or metastatic solid tumor, GT201, when infused after FC lymphodepletion and followed by high dose IL-2, exhibits a manageable safety profile. Notably, GT201 has demonstrated a favorable clinical profile in NSCLC, with an encouraging objective response rate, response durability, and no GT201-treatment related grade≥3 AEs. Clinical trial information: NCT05729399 .

Phase 1 study of GT101 as an autologous tumor infiltrating lymphocyte (TIL) therapy in advanced solid tumors.

2548 Background: Adoptive cell therapy utilizing autologous TIL has demonstrated efficacy and durable long-term responses in patients with certain advanced solid tumors progressed after conventional therapies. We present data from 14 patients enrolled in the study of GT101, a Phase 1, open-label, single-arm, multicenter trial (NCT05430373) of autologous TIL therapy, aiming to investigate the safety profile, efficiency trend and the duration of response. Methods: The trial was designed with the primary endpoint on evaluating DLT and characterizing the safety profile of GT101 in solid tumor patients measured by the incidence of Grade ≥ 3 treatment-emergent adverse events (TEAEs). The secondary endpoints were to assess efficacy parameters including overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), duration of response (DOR), and overall survival (OS) according to RECIST v1.1. Results: As of November 10, 2023, a cohort of 14 patients received treatment with a median age of 46.9 and a median of 2.6 lines of prior therapies. Following a standard FC-based lymphodepletion, patients underwent GT101 infusion at doses ≥ 5x109 cells with median dose of 3.7x1010 cells, followed by high-dose IL-2 administration. Most of observed Grade ≥ 3 AEs were related to the FC conditioning regimen and IL-2, including decreased lymphocyte count, decreased white blood cell count, decreased neutrophil count, anemia, pyrexia and decreased platelet count. The majority of these AEs were recovered within 14 days, while a few were downgraded to ≤ Grade 2 within 4 weeks. Among 14 enrolled patients across various indications (small-cell-lung cancer, melanoma, cervical cancer), the ORR was 35.7%. Specifically, 4 pts (28.6%) had a confirmed partial response (PR), 1 pt (7.1 %) achieved complete response (CR), and 8 pts (57.1 %) had stable disease (SD) as their best response. One pt had unconfirmed disease progression (PD). Notably, among 11/14 patients with cervical cancer, the ORR was 45.5% (5/11) with 4 pts (36.4%) achieving PR and 1 pt (9.1 %) achieving CR. Disease control was observed in 10/11 pts (90.9%), and the median PFS was 4.2 months for this cohort. The CR patient underwent a long-term follow-up and the duration of CR and PFS (estimated by Kaplan-Meier) was 24 weeks and 36 weeks, respectively. Post GT101 infusion, T cell expanded robustly in the peripheral blood of all patients with median Tmax 6.83 days and average 15.9 days. Conclusions: In the GT101 Phase 1 study, no treatment-related SAEs and DLT were observed. In patients with heavily pretreated advanced or metastatic solid tumors, GT101 exhibited a manageable safety profile under the treatment protocol of lymphodepletion and high-dose IL-2 and a favorable clinical profile, particularly in cervical cancer, with an encouraging ORR and sustained response duration. Clinical trial information: NCT05430373 .

EXPRESS study: A trial exploring the association of low level of genomic alteration with exceptional and unexpected response to targeted therapies in patients with advanced solid tumors.

e15140 Background: Small subsets of pts treated with targeted therapies (TT) present exceptional and unexpected response (1-10%), which could be driven and correlated by a low level of genomic alterations in genes identified as causally implicated in cancer. Conversely, the multiplication of the genomic alterations in such genes would decrease the oncogenic de-addiction process. Methods: EXPRESS is an exploratory, multicenter, prospective trial conducted in pts with locally advanced or metastatic solid tumors, who presented an exceptional and unexpected response to an antineoplastic TT. This research aimed to explore whether tumors with a low level genomic alteration (mutation, amplification, deletion) as assessed by whole exome sequencing (WES) are associated with exceptional and unexpected response. Secondary endpoints including the identification of novel candidate somatic molecular profiles and host immunologic characteristics susceptible to drive exceptional and unexpected response will be reported later. Results: 439 pts were identified over 32 centres from December 2016 to April 2021. Out of 270 pts confirmed with an exceptional response by our review committee of cases, 183 were included in the EXPRESS study. Exceptional responder population is summarised (Table). Out of 183, WES analysis was performed for 103 pts (56.3%). Genomic analysis failure was predominant in the breast and lung cohort (60.9% and 52.5%). The number of genomic alterations in the EXPRESS cohort was lower than in the TCGA control cohort (median[Q1-Q3]: 11[7-17] vs 19 [11-32], p<0.001). A lower number of genomic alterations was also reported in the melanoma (8[5-13] vs 33[17-51], p<0.001) and lung cancer cohort (8[5-17] vs 22[13-34], p<0.001) but not in the breast and kidney cohorts (13[10-21] vs 17[10-29], p=0.41 and 12[9-14] vs 11[7-17], p=0.89). Conclusions: Compared to the TCGA cohort, a low level of genomic alteration is associated with exceptional response in pts with lung cancer and melanoma. A comparison with a matched population based on genomic criteria in the TCGA is undergoing and will be presented at the conference. Clinical trial information: NCT02701907 . [Table: see text]

A phase 1, first-in-human study of CUSP06, a cadherin-6 (CDH6) -directed antibody-drug conjugate, in patients with platinum-refractory/resistant ovarian cancer and other advanced solid tumors.

TPS3166 Background: Cadherin-6 (CDH6) is a transmembrane glycoprotein involved in cancer metastasis and invasion expressed in various tumor types including ovarian cancer (OC), renal cell carcinoma (RCC), papillary thyroid cancer, cholangiocarcinoma, hepatocellular cancer, glioma, uterine serous carcinoma and non-small cell lung cancer. CUSP06 is an antibody-drug conjugate composed of a human IgG1 monoclonal antibody against CDH6 conjugated with a protease-cleavable linker, T1000, to exatecan, a topoisomerase I inhibitor payload. In preclinical studies, CUSP06 showed CDH6-dependent cell growth inhibition in ovarian cancer cell lines. High CDH6-expressing ovarian and renal CDX and PDX models demonstrated tumor regression after treatment with CUSP06, as did low CDH6-expressing PDX models of other solid tumors. Methods: This is a Phase 1a/1b, open-label, multicenter dose escalation and expansion study to evaluate safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), recommended Phase 2 dose (RP2D), and preliminary efficacy of CUSP06 in patients with platinum-refractory/resistant ovarian cancer (PRROC), advanced RCC and other advanced CDH6-positive solid tumors. Patients with advanced solid tumors previously treated with standard of care systemic therapy, or for whom no standard therapy is available are eligible for enrollment. Prescreening for CDH6 expression will be required for those patients with solid tumors other than PRROC or RCC. CUSP06 will be administered intravenously every 21 days. Phase 1a will follow a standard 3+3 dose escalation design. Phase 1a also includes up to 3 dose enrichment cohorts at doses that have demonstrated safety, each with a maximum of 18 patients, to generate additional safety, PK, PD, and preliminary efficacy data to support an optimized dose for expansion. Phase 1b consists of several dose expansion cohorts including PRROC, RCC, and other CDH6-positive solid tumors, to be enrolled according to Simon's 2-stage design. Mandatory pre- and on-study biopsies in dose expansion cohorts will support a robust exploratory biomarker plan that may include correlation of CDH6 levels with response, and other RNA and protein markers of sensitivity and resistance. The study is currently enrolling in Phase 1a dose-escalation. Clinical trial information: NCT06234423 .

A phase I study of TAK-659 and paclitaxel in patients with taxane-refractory advanced solid tumors.

3152 Background: Paclitaxel resistance in patients is a clinical challenge that limits the durability of clinical benefit in patients with taxane-responsive advanced solid tumors. One proposed mechanism for this resistance is overexpression of spleen tyrosine kinase (SYK); which can be inhibited with new molecules including TAK-659. In this phase I study, we have investigated the combination of TAK-659 and paclitaxel in patients with taxane-refractory advanced solid tumors; hypothesizing that use of TAK-659 would help to overcome resistance to prior taxane-based therapy. Methods: We included patients with advanced solid tumors who received and progressed on prior taxane-based therapy. Patients received treatment with intravenous paclitaxel on day 1,8, and 15 in addition of daily TAK-659 in 28-day cycles. Six cohorts were treated during dose escalation at different dose levels followed by a dose expansion phase in patients with advanced ovarian cancer. We used the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 for evaluation of toxicity and Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 for assessment of preliminary efficacy. Results: We included 49 patients with advanced solid tumors. The maximum tolerated dose was not reached in this study; and no patients experienced treatment-related deaths. Most adverse events were either grade 1 or 2. Grade 3 or more adverse events were reported in 47% of patients (n=23). The most common grade ≥3 adverse events were decreased neutrophil count (n=7; 14%), elevated lipase (n=6; 12%), anemia (n=5; 10%), increased amylase (n=4; 8%), and decreased white blood cell counts (n=4; 8%). In 44 patients with taxane-refractory tumors who were evaluable for efficacy, 9% (n=4) had RECIST partial response and 27% (n=12) had RECIST stable disease, including 3 patients with prolonged stable disease for at least 6 months. Conclusions: The combination of paclitaxel and TAK-659 was well tolerated and showed preliminary modest efficacy which could be possibly overcoming resistance to taxane-based therapy in patients with advanced solid tumors. Clinical trial information: NCT03756818 .

A multicenter, open-label, phase 1a study of HC-5404 in patients with advanced solid tumors.

e15118 Background: Tumor cells have been shown to adapt to the endoplasmic reticulum (ER) stress resulting from activated oncogenes, nutrient stress, and hypoxia by activating one of the kinases in the Unfolded Protein Response (UPR) pathway, Protein kinase RNA-like Endoplasmic Reticulum Kinase (PERK). This adaptation enables them to survive these stresses and develop resistance to standard of care. Targeting PERK in cancer cells could disrupt their ability to thrive under adverse conditions, potentially leading to apoptosis. HC-5404 is a novel, highly selective and potent PERK inhibitor that demonstrates bioavailability and target engagement at efficacious doses across preclinical tumor models. Herein, we report clinical data from the Ph1a study evaluating HC-5404 in patients with advanced solid tumors. Methods: In this first-in-human trial, HC-5404 was administered orally in 21-day cycles to patients ≥18 years old with advanced solid tumors. A Bayesian Optimal Interval (BOIN) design was employed to escalate through 7 dose levels (25 mg to 600 mg BID). Dose Limiting Toxicity (DLT) was assessed during the first cycle. The primary objectives were to establish the Maximum Tolerated Dose (MTD) and evaluate the safety and tolerability of HC-5404. The secondary objectives included evaluating PK/PD and antitumor activity (response rate and survival outcomes). Results: 23 patients received HC-5404 across various dose levels. Of these, 47.8% were ≥ 65 years old, 52.2% were male, and 82.6% had received ≥3 prior therapies. Overall, 1 partial response (PR) with a duration of 130 weeks was observed in a renal cell carcinoma (RCC) patient who started at the 25 mg dose and was escalated to 50 mg, while 8 patients had stable disease (SD) as best overall response. Three DLTs were observed, including hyperglycemia (300 mg), increased AST, ALP, GGT (200 mg) and decreased ejection fraction (EF) (100 mg). Hyperglycemia was observed only at higher doses (≥300 mg) above clinically relevant exposures of 25-100 mg. The MTD was not established. Treatment-related adverse events (TRAEs) of any grade occurred in 69.6% of patients with common events (≥ 20%) including nausea, fatigue, diarrhea, and dry mouth. Grade ≥3 TRAEs occurred in 17.4% of patients and included hyperglycemia, acute myocardial infarction, decreased EF, increased troponin, AST, GGT, ALP, and lipase. HC-5404 PK analysis showed rough dose-proportionality across 25-600mg doses and PK/PD analyses demonstrated the human dose range of 25-100 to be functionally equivalent to the pre-clinical efficacious doses. Final analysis of safety and clinical response are ongoing. Conclusions: HC-5404 showed a favorable safety profile and encouraging preliminary efficacy in heavily pretreated patients with advanced solid tumors. Safety and exposure-response analyses support further exploration of the 25-100 mg dose level of HC-5404, as monotherapy and in novel combinations. Clinical trial information: NCT04834778 .

Intravenous infusion (IV) or intracavitary perfusion (IP) of T3011, an oncolytic HSV expressing IL-12 and PD-1 antibody: Analyses of two phase 1 studies.

e14581 Background: T3011 is a recombinant HSV-1 oncolytic virus expressing both IL-12 and anti-human PD-1 antibody. Upon delivery, locally produced IL-12 and PD-1 induces IFN-γ production, enhances the oncolytic activity of NK cells and cytotoxic T lymphocytes, promotes anti-angiogenesis, and inhibits tumor growth. We present the results of T3011 monotherapy administered via IV in advanced solid tumors or IP for malignant pleural effusion/ascites. Methods: In a phase 1, dose-escalation and expansion study using a 3+3 design with 5 cohorts (1×106, 1×107, 1×108, 5×108, 1×109 PFU), T3011 was administered intravenously on Days 1, 4, 8, 11,15,18 of a 28-day cycle in pts with advanced solid tumors. The primary objective was to evaluate the safety and tolerability of IV T3011, characterize dose-limiting toxicities (DLTs), MTD or RP2D, pharmacokinetic and pharmacodynamic profiles. In another pilot study to evaluate the safety and efficacy of T3011 in pts with malignant pleural effusion or ascites, T3011 was infused into the pleural or peritoneal cavity through an indwelling catheter on Days 1, 4, 8, 11 with 2 cohorts (5×108, 2×109 PFU). The response of malignant pleural effusion or ascites was assessed by WHO criteria. Results: As of 15 Dec 2023, 18 pts were enrolled and treated with IV T3011,4 pts received IV T3011 therapy at the highest dose level, 1×109 PFU. T3011 was well tolerated without ≥ Grade 3 TRAEs or DLTs. MTD was not reached. The most common TRAEs (≥ 10%) were nausea and infusion-related reactions, diarrhea, etc. Among 14 evaluable pts with advanced solid tumors, 3 pts had confirmed SD per RECIST1.1 and tumor burden reduced significantly. All the pts had detectable T3011 DNA in blood within 0.5-2 hours after administration, which was cleared subsequently within 3-7 days. As of 5 Jan 2024, 6 pts (pleural effusion 3, ascites 3) were dosed with IP T3011. 2 pts received 5×108 PFU and 4 pts received 2×109 PFU. Most TEAEs were grade 1 or 2. Only 1 pt developed grade 3 leukopenia, which resolved with G-CSF. No SAE occurred. 3 pts with pleural effusion showed 1 CR, 1 PR and 1 SD. 3 pts with malignant ascites secondary to advanced colorectal cancer, 1 was evaluable with PR. Conclusions: IV T3011 monotherapy has a very manageable safety profile and some encouraging activity in advanced solid tumors. IP T3011 monotherapy is also well tolerated and demonstrates promising activity against malignant pleural effusion and ascites. Clinical trial information: NCT04780217 .

A phase 1 study of HRS-1167 (M9466), a highly selective PARP1 inhibitor, in patients (pts) with advanced solid tumors.

3154 Background: The use of first-generation dual PARP1/2 inhibitors is limited due to their hematological toxicities and inevitable drug resistance. Given that loss of PARP1 is the primary driver of synthetic lethality in homologous recombination repair (HRR) deficient tumors, and PARP2 is largely associated with hematological toxicities, development of next-generation PARPi with selectivity for PARP1 is warranted. Here, we present results of the dose escalation (D-ESC) and dose expansion (D-EXP) parts of a first-in-human study of HRS-1167 (M9466), a highly selective PARP-1 inhibitor, in pts with advanced solid tumors. Methods: Pts were eligible for the D-ESC part if they had advanced solid tumors that had progressed on standard therapies or for which no standard therapies were available. The D-ESC part began with accelerated titration (30 mg; QD) and then switched to the BOIN design (50, 100, 200, and 300 mg; QD). In the D-EXP part, previously treated pts harboring germline or somatic BRCA1/2, PALB2, or RAD51C/D mutations received HRS-1167 at 50, 100, and 200 mg QD. Prior PARPi was allowed. The primary objectives were to assess the safety and tolerability of HRS-1167. Results: As of Nov 20, 2023, 40 pts were enrolled (median lines of prior treatment, 2 [range, 1–5]; prior PARPi, 15.0%). No dose-limiting toxicities occurred, and the maximum tolerated dose was not reached. Grade ≥3 treatment-related adverse events occurred in 12 (30.0%) pts, with the most common being anemia (6 [15.0%]), decreased neutrophil count (5 [12.5%]), and decreased WBC count (5 [12.5%]). Of the 24 pts with HRR mutations who had at least one post-baseline assessment for tumor response, 10 (41.7%) pts had objective responses (8 ovarian cancer, 1 prostate cancer, and 1 pancreatic cancer). PK exposures were approximately dose-proportional. The median Tmax was 1.0–1.5 h, and the mean t1/2 was 10.5–15.0 h following a single dose of HRS-1167 at 30–300 mg. No obvious drug accumulation was observed (Rac, 1.08–1.30 for Cmax; 1.29–1.62 for AUC0-24). Conclusions: HRS-1167 was well-tolerated and exhibited favorable safety and PK profiles in pts with advanced solid tumors, and demonstrated promising anti-tumor activity in pretreated pts with HRR mutations. Clinical trial information: NCT05473624 .

A phase 1, open-label, dose escalation and dose expansion study to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of PF-07799544 (ARRY-134) as a single agent and in combination with PF-07799933 BRAF dimer inhibitor, in participants 16 years and older with advanced solid tumors.

TPS3180 Background: The MAPK pathway plays a role in several key signaling and phosphorylation events that contribute to tumorigenesis. Inhibition of MEK, along with RAF kinases, has proven to be a successful transformative strategy for melanoma and other MAPK pathway-altered tumors. However, the duration of clinical benefit is limited by a narrow therapeutic index, de novo and acquired resistance and poor brain penetration. PF-07799544 is a next-generation, fully brain penetrant MEK inhibitor. PF-07799933 is an oral selective ATP-competitive small-molecule RAF kinase inhibitor that suppresses BRAF signaling in BRAF V600-mutant and non-V600-BRAF mutant tumors. It displays significantly less paradoxical activation than approved BRAFi and is not “pan RAF” as it spares non-BRAF mutated-containing RAF dimers. We describe here the design of the Phase 1 study of PF-07799544 as Monotherapy or in Combination with a next generation BRAF dimer inhibitor PF-07799933 in participants with BRAF mutated (BRAFm) advanced solid tumors. Methods: The purpose of this first-in-human study is to investigate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics, and potential clinical benefits of PF-07799544 administered as a single agent in participants with advanced solid tumors (Phase 1a) and in combination with PF-07799933 in participants with BRAF Class 1, 2 and 3 mutated solid tumors with or without brain involvement (Phase 1b). Phase 1a will enroll participants with advanced solid tumors who have progressed on standard of care. The primary objective is to determine monotherapy MTD/RDE of PF-07799544. Once PK measurements indicate the potential for significant WT MEK mutation target coverage, participants with untreated and symptomatic brain metastases (bm) will be allowed to enroll. Phase 1b is comprised of multiple sub-studies, all of which evaluate PF-07799544 in combination with PF-07799933 in participants with BRAFm solid tumors who have progressed on standard of care therapies, including Class 1 BRAFi where indicated. Sub-study B: BRAFm melanoma (V600 and non-V600) will determine the MTDc/RDEc of the combination (Part 1 primary objective), followed by dose expansion cohorts (Part 2) (~80 participants): Cohort 1: BRAF V600 melanoma (asymptomatic and untreated bm permitted), Cohort 2: BRAF V600 melanoma (symptomatic bm), Cohort 3 BRAFm Class 2/3 melanoma (asymptomatic and untreated bm permitted); Sub-study C: BRAFm Class 2 or 3 advanced solid tumor Cohort 1 (asymptomatic and untreated bm permitted and Cohort 2 (symptomatic bm) (~20 each cohort). The main objectives of the dose expansion cohorts in all substudies, will be to evaluate anti-tumor activity, safety, PK and PD. Clinical trial information: NCT05538130 .

A phase 1a/b, multi-regional, first-in-human study of CS5001, a novel anti-ROR1 ADC, in patients with advanced solid tumors and lymphomas.

3023 Background: Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an embryonic tyrosine kinase-like molecule implicated in multiple pathways promoting oncogenic signaling. ROR1 is overexpressed in a broad spectrum of solid tumors and hematological malignancies while notably absent in normal tissues. CS5001 is an antibody drug conjugate (ADC) composed of a human anti–ROR1 IgG1 monoclonal antibody which is site-specifically conjugated to a pyrrolobenzodiazepine dimer prodrug through a proprietary lysosomal cleavable β-glucuronide linker. Here, we report preliminary phase 1a results of CS5001 in patients (pts) with advanced solid tumors and lymphomas. Methods: This is a global, first-in-human, phase 1a/b study evaluating the safety, pharmacokinetics (PK), and anti-tumor activity of CS5001 in pts with advanced solid tumors and lymphomas. CS5001 was administered intravenously Q3W with a 42-day-DLT period. In phase 1a (dose escalation), pts who had progressed on or been intolerant to standard therapies were enrolled without baseline ROR1 expression testing; accelerated titration followed by Bayesian Optimal Interval design was employed; in parallel with dose escalation, additional pts were enrolled to selected dose levels deemed safe to further evaluate safety and efficacy. Results: As of 15 Jan 2024, 49 pts with lymphomas (n=17) and solid tumors (n=32) were treated across 8 dose levels (7 to 125 μg/kg). Median age was 57 years. Most (n=40, 81.6%) pts had received ≥3 lines of prior anti-tumor treatment. No DLT was observed and MTD was not reached. Treatment-related adverse events (TRAEs) occurred in 29 pts (59.2%); the most common TRAE was fatigue (n=8, 16.3%). Grade 3 TRAEs occurred in 7 pts (14.3%), with fatigue, gamma-glutamyltransferase increased and pneumonia being the most common (occurring in 2 pts [4.1%] each). No grade 4-5 TRAEs were reported. Drug exposure of CS5001 was proportional to dose in general, with an apparent half-life of about 5 days. The PK profile of CS5001 was similar to that of total antibody, indicating good stability of the ADC in the circulation. Among the 34 pts with post baseline tumor assessment (13 lymphomas and 21 solid tumors), objective responses were observed in pts at dose level 5 or above (n=23), including 2 complete responses (1 Hodgkin lymphoma [HL] and 1 diffuse large B-cell lymphoma) and 3 partial responses (2 HL and 1 pancreatic cancer). Stable diseases were observed in 3 pts (2 colorectal cancer and 1 renal cancer). Dose escalation is still ongoing, and more data will be available at the conference presentation. Conclusions: CS5001 was well tolerated with no DLT identified, PK characteristics were as expected, and encouraging antitumor activities were observed in various advanced solid tumors and lymphomas. Current data support continued evaluations for the recommended phase 2 dose and subsequent phase 1b dose expansion. Clinical trial information: NCT05279300 .

First-in-human study of HMPL-295, an ERK1/2 inhibitor, in patients with advanced solid tumors: Dose-escalation results of monotherapy.

e15112 Background: HMPL-295 (’295) is an extracellular signal-regulated kinase 1 and 2 (ERK1/2) inhibitor with potent activity in non-clinical studies. This is a first-in-human, dose escalation study of ’295 in patients (pts) with advanced solid tumors. Here, we report the results of the mono dose escalation stage. Methods: Pts with advanced solid tumors who have failed standard therapy were enrolled to receive ’295 once daily (QD) in 28-day cycles or ’295 QD 2 weeks on/1 week off (2w on/1w off) in 21-day cycles. The mTPI-2 design was used for dose escalation, having explored from 5 to 75 mg QD in 6 cohorts, as well as 75 mg and 100 mg QD 2w on/1w off. The study aims to determine the maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D), safety, tolerability, pharmacokinetics/pharmacodynamics (PK/PD), and preliminary efficacy (best of response, BOR). Results: As of Dec 11, 2023, 47 pts with advanced solid tumors were enrolled (n=1, 1, 3, 6, 12, 5, 13, 6 in 5, 10, 20, 40, 50, 75 mg QD cohorts, 75, 100 mg QD 2w on/1w off cohorts, respectively), with a median age of 58 years, 23 (48.9%) male pts. During the dose escalation from 5 to 75 mg QD cohort, 1 pt given 40 mg QD experienced a dose-limiting toxicity (DLT) of grade 3 dermatitis acneiform and 2 pts given 75 mg QD experienced DLTs of grade 3 rash and acute kidney injury (AKI). As for intermittent-administration cohorts, 2 pts given 100 mg QD 2w on/1w off experienced DLTs of grade 3 AKI and rash maculo-papular. After multiple-dose oral administration, ’295 plasma concentrations reach peak at 1.0-2.0 hours post dose and the exposure (Cmax and AUC) displayed dose dependent increase. The accumulation ratio (AUC) was 2.1–3.4 after repeat dosing, reaching steady-state around day 15. ’295 inhibited ribosomal S6 kinase (RSK) phosphorylation which is a downstream signaling molecule regulated by ERK1/2 and stimulated by phorbol 12-myristate 13-acetate (PMA). The BOR was partial response each in 1 pt with duodenal adenocarcinoma in 40 mg QD cohort,1 pt with endometrial cancer in 50 mg QD cohort and 1 pt with non-small cell lung cancer (NSCLC) in 75 mg QD 2w on/1w off cohort. Stable disease with tumor shrinkage was also observed in 2 pts with NSCLC on 50 mg QD and 75 mg QD 2w on/1w off cohort respectively, and 1 pt with pancreatic ductal adenocarcinoma in 100 mg QD 2w on/1w off cohort. 25 (53.2%) pts reported grade ≥3 TEAEs. The most common (≥10.0%) ≥ grade 3 TEAEs were rash (10.6%) and anemia (10.6%). Conclusions: Considering safety, tolerability, PK/PD and preliminary efficacy results, RP2D was determined to be 50 mg QD. Clinical trial information: NCT04908046 .

Safety and preliminary efficacy results of IBI389, an anti-CLDN18.2/CD3 bispecific antibody, in patients with solid tumors and gastric or gastro-esophageal tumors: A phase 1 dose escalation and expansion study.

2519 Background: CLDN18.2 expression has been observed in various solid tumors especially in gastric cancer, indicating its potential as a novel target for anti-tumor therapy. IBI389 is an anti-CLDN18.2/CD3 bispecific antibody that induces immune synapse formations by linking CD3 molecules in T-cell receptor complexes and CLDN18.2 antigens on the membrane of tumor cells. Herein, we report preliminary results from a phase I study to evaluate safety and efficacy of IBI389 in patients (pts) with advanced solid tumors. Methods: Eligible pts with advanced solid tumors who failed or were intolerant to standard treatments were enrolled. The dose escalation of IBI389 monotherapy used intra-patient dose escalation with accelerated titration and the classic 3+3 design (0.003 µg/kg to 600 µg/kg). Selected dose levels were expanded in pts with advanced gastric/gastroesophageal junction cancer (G/GEJ C) and pancreatic ductal adenocarcinoma (PDAC). The primary objective was safety. Secondary objective was efficacy assessed by investigator per RECIST v1.1 including objective response rate (ORR) and disease control rate (DCR). Results: As of January 9, 2024, a total of 114 pts were enrolled (males: 67.5%, median age: 60.0 years, G/GEJ C: 32.5%, PDAC: 57.9%, stage IV: 81.6%). No dose-limiting toxicity (DLT) was observed during dose escalation. The MTD was not reached. In all pts, treatment-emergent adverse events (TEAEs) occurred in 112 (98.2%) pts including 76 (66.7%) pts with grade ≥3 TEAEs. Treatment-related adverse events (TRAEs) occurred in 111 (97.4%) pts including 63 (55.3%) pts with grade ≥3 TRAEs. The most common grade ≥3 TRAEs (≥ 4%) were gamma-glutamyl transferase increased (21.9%), lymphocyte count decreased (13.2%) and nausea (4.4%). Cytokine release syndrome (CRS) related adverse events occurred in 65 (57.0%) pts including 1 (0.9%) pts with grade 3 CRS and no grade 4 or 5 CRS. TEAEs leading to dose interruption and treatment discontinuation occurred in 44 (38.6%) and 8 (7.0%) pts. Preliminary efficacy of IBI389 was observed in pts with CLDN18.2 expression ≥10% (immunohistochemistry 2+/3+). In G/GEJ C pts with previous treatments ≥2 lines receiving IBI389 at various dose levels ranging from 10µg/kg to 600 µg/kg (n=26), 8 pts had partial response (PR) and 11 pts had stable disease (SD). The ORR was 30.8% (95%CI: 14.3-51.8) and DCR was 73.1% (95%CI: 52.2-88.4). Conclusions: IBI389 showed manageable safety profiles in pts with advanced solid tumors and preliminary efficacy in CLDN18.2-positive pts with G/GEJ C. Clinical trial information: NCT05164458 .

Safety, tolerability, pharmacokinetics and clinical activity of AST-3424, an AKR1C3-activated bis-alkylating moiety prodrug, in subjects with advanced solid tumors in China: A phase I dose-escalation study.

3121 Background: Aldo-keto reductase family 1 member C3 (AKR1C3) modulates cellular differentiation and proliferation through indirect regulation of ligand access to hormone and nuclear receptor signaling. AKR1C3 is expressed at high levels in various human cancers, including hepatocellular carcinoma (HCC). AST-3424 is an AKR1C3-activated prodrug and releases a toxic bis-alkylating moiety (AST-2660) in the presence of AKR1C3, which forms intra- and inter-strand DNA crosslinks resulting in cell death. Here we report the results of a phase I dose escalation study of AST-3424 in patients with advanced solid tumors (NCT06239155). Methods: Patients with histologically and/or cytologically confirmed advanced solid tumors who failed standard treatment or no standard treatment, or not suitable for standard treatment were enrolled to receive AST-3424 intravenously (i.v.) at doses of 1, 2, 4, 6, 8 mg/m2 on Day 1 and Day 8 every 21 days. A parallel and accelerated titration for 1 and 2 mg/m2, and 3+3 dose escalation design for other cohorts were used to guide dose escalation and maximum tolerable dose (MTD) determination. Results: 21 subjects were enrolled and received at least one treatment (HCC=4, colorectal cancer=6, gastric cancer=4, pancreatic carcinoma=2, breast cancer=2, intrahepatic cholangiocarcinoma=1, prostate cancer=1, salivary gland cancer=1). 4 dose-limiting toxicities (DLTs) were observed (3 grade 4 platelet count decreased; 1 grade 2 gamma-glutamyltransferase increased, DLT reported due to dosing delayed more than 14 days). Safety Review Committee confirmed 6.0 mg/m2 as the MTD and recommended Phase 2 dose (RP2D). Grade≥3 adverse events (AEs) were observed in in 10 patients (47.6%). 8 patients (38.1%) had grade≥3 treatment-related AEs (TRAEs), being anemia (33.3%), platelet count decreased (19.0%), white blood cell count decreased (9.5%) and neutrophil count decreased (9.5%). Most of the grade≥3 AEs were observed in the 8.0 mg/m2 cohort. No patient had a fatal TRAE. 15 subjects with baseline target lesions had at least one post baseline assessment. 9 subjects (42.9%) had stable disease (SD); 1 subject (4.8%) had non-complete remission/non-disease progression (Non-CR/Non-PD); 5 subjects (23.8%) had progressive disease (PD). AST-3424 showed linear pharmacokinetic characteristics in the range of 1.0-8.0 mg/m2 with a half-life of 0.16-0.40 hours. AST-2660 showed linear pharmacokinetic characteristics in the range of 4.0-8.0 mg/m2 with a half-life of 1.59-2.08 hours. Conclusions: AST-3424 showed a tolerable safety profile and preliminary anti-tumor activity in advanced solid tumors. The phase II dose expansion phase of AST-3424 monotherapy is ongoing in subjects diagnosed as advanced HCC and with high AKR1C3 expression. Clinical trial information: NCT06239155 .

Molecularly matched therapies identified by comprehensive genomic profiling before the first-line setting to provide alternative treatment outcomes in patients with solid tumors: 1-year follow-up of the prospective FIRST-Dx study.

3137 Background: Comprehensive genomic profiling (CGP) test by next-generation sequencing has been reimbursed in Japan since 2019. However, only 9.4% of patients (pts) had received molecularly-matched treatment because CGP test in Japan is only indicated after standard of care (SoC). To determine the clinical utility of a CGP test (FoundationOne CDx) in the first-line setting for pts with advanced solid tumors, we previously reported the results of the FIRST-Dx study, in which the molecular tumor board identified molecular-based recommended therapy (MBRT) for 61% of pts (105/172) (Matsubara J, et al. JAMA Netw Open 2023). In this 1-year follow-up of the FIRST-Dx study, we investigated the clinical benefits provided by the upfront CGP test. Methods: The FIRST-Dx study was a multi-institutional, prospective study in 6 hospitals in Japan. Chemotherapy-naïve adult pts with advanced solid tumor (GI, Lung, Breast, GYN, Melanoma) and ECOG performance status of 0-1 were enrolled. This follow-up study was planned for 3 years and an interim analysis was prespecified at 1 year after the final patient enrollment in the FIRST-Dx study. Primary endpoint was overall survival (OS). Secondary endpoints were the proportion of pts who received MBRT, overall response rate, progression-free survival (PFS), and a PFS ratio (PFS on MBRT/PFS on prior therapy). Results: Data from 172 pts with a median follow-up of 15.1 months were available. Median OS was not reached (95% CI: 18.4 months to not reached). Thirty-nine pts (22.7%) had received MBRT. The total number of pts treated with MBRT were 21 in 1st-line, 20 in 2nd-line, 4 in 3rd-line, and 1 in 4th-line, respectively. Overall response rate was 56.3% [95% CI: 29.9-80.2%] in 1st-line MBRT group vs 42.3% [95% CI: 33.9-51.1%] in 1st-line SoC (N=137), and 26.3% [95% CI: 9.1-51.2%] in 2nd-line MBRT group vs 17.1% [95% CI: 9.7-27.0%] in 2nd-line SoC (N=82), respectively. Median PFS was 12.9 months [95% CI: 7.4 months to not reached] in 1st-line MBRT group vs 11.3 months [95% CI: 8.6-14.1 months] in 1st-line SoC, and 6.9 months [95% CI: 2.8 months to not reached] in 2nd-line MBRT group vs 5.7 months [95% CI: 3.7-7.4 months] in 2nd-line SoC, respectively. Regarding the PFS ratio of 2nd-line MBRT (N=15) (PFS on MBRT in 2nd-line/PFS on 1st-line therapy), median PFS ratio was 1.0 (range: 0.1-14.6) and 4 pts (27%) had the PFS ratio of >1.3, indicating that MBRT might be effective in changing the clinical outcome (Von Hoff DD, et al. J Clin Oncol 2010). Conclusions: We showed that MBRT identified by CGP test before the first-line setting provides better treatment outcomes than SoC in pts with solid tumors early in their disease course. Our data suggested that the timing of CGP test in Japan for pts with advanced solid tumors should be indicated before starting SoC. Clinical trial information: jRCT1050220041 .

First-in-human study of ZGGS15, a dual specific antibody targeting LAG-3 and TIGIT, as monotherapy in patients with advanced solid tumors.

e14678 Background: ZGGS15 is a recombinant humanized bispecific antibody composed of a monoclonal antibody against LAG-3 and TIGIT. It can specifically bind LAG-3 and TIGIT. It reverses LAG-3 and TIGIT immune suppression to T and NK cells, relieves suppression of Treg to T and NK cells, promotes the activation and proliferation of T and NK cells, and cytokines release. ZGGS15 restores T and NK cell functions to kill tumor cells. In non-clinical studies, we found that ZGGS15 had significant anti-tumor effects and synergistic anti-tumor effects with Anti-PD-1 antibody. Therefore, we conducted a Phase 1 clinical study to assess the tolerability, safety, and preliminary efficacy of this drug as monotherapy in patients with advanced solid tumors. Methods: During the dose escalation stage, an accelerated titration design (ATD) in the first dose (1 subject if ≤Grade 2 treatment-related adverse event occurred) and the standard "3+3" design in the rest doses were used. Subjects were patients with advanced solid tumors who failed to the available standard treatments. The dose groups were set from 0.3 to 30 (0.3, 1, 3, 10, 20, 30) mg/kg, intravenous infusion, once every 3 weeks. The first 21-day period was defined as the dose-limiting toxicity (DLT) observation period. Subjects could continue to receive ZGGS15 until treatment discontinuation criteria were met. Tumor response was assessed by RECIST1.1 and iRECIST. Pharmacokinetics (PK) and receptor occupancy (RO) profiles were also assessed in this study. Results: A total of 12 patients (4 males and 8 females) completed the DLT observation in the first four dose groups (0.3 to 10 mg), with a median age of 57 years. Eight (66.7%) of them received at least 3 lines of antineoplastic therapies, and five (41.7%) have been exposed to PD-1 or PD-L1 inhibitors. There was no DLT event observed. Thirty-eight treatment-related adverse events (TRAEs) occurred. Up to now, TRAEs were all grade 1 ~ 2. The most frequent TRAEs were proteinuria (33.3%, 4/12), hypokalemia (25%, 3/12), hypoalbuminemia (25%, 3/12), and hypertriglyceridemia (25%, 3/12). The Cmax and AUC increased from 0.3-1 mg/kg approximately in dose proportion. Nearly complete and sustained RO of T and NK cells in PBMCs was observed at 1 mg/kg dose of ZGGS15 for at least 3 weeks. Conclusions: The first four dose levels of ZGGS15 were very well tolerated. A good PK profile, and a long-lasting RO were observed in this escalation study. It is anticipated that this product could provide an additional benefit only when use in combination with an anti-PD-1 antibody. Clinical trial information: NCT05864573 .

Phase Ib study of a high potent PI3K-mTOR dual inhibitor WX390 combined with toripalimab in patients with advanced solid tumors.

e14627 Background: WX390 is a high potent PI3K-mTOR dual inhibitor targeting pan-PI3K and mTOR. It modulates the tumor immune microenvironment by decreasing tumor Treg and myeloid-derived suppressor cells (MDSC) and improves the immune response to checkpoint inhibitors (CPI) in preclinical models. Methods: The Phase Ib study was designed to evaluate safety, pharmacokinetics (PK), and preliminary clinical activity, to determine recommended phase 2 dose (RP2D) of WX390 combined with Toripalimab in patients with advanced solid tumors. WX390 was administered orally daily at escalating doses of 0.7 mg, 0.9mg and 1.1mg, with Toripalimab at 240 mg IV every 3 weeks until confirmed progressive disease, intolerable toxicity or withdrawal of consent. Plasma PK samples were collected up to 24 hours after the first dose at C1D1, and up to 24 hours before and after the morning dose at C1D21. Results: As of December 31, 2023, total 18 patients had been treated in 3 WX390 cohorts: 0.7 mg (n = 3), 0.9 mg (n = 3), and 1.1 mg (n = 12) once daily (QD). No dose limit toxicity (DLT) was observed, and the RP2D of WX390 in combination was 1.1 mg QD, which was consistent with the single agent RP2D. The treatment related adverse events (TRAEs) (≥20%) included hyperglycemia (17/18, 94.4%), creatinine increased (12/18, 66.7%), weight loss (10/18, 55.6%), diarrhea (9/18, 50%), proteinuria (9/18, 50%), nausea (7/18, 38.9%), lymphocytopenia (7/18, 38.9%), vomiting (7/18, 38.9%), rash (7/18, 38.9%), decreased appetite (6/18, 33.3%), hypokalemia (6/18, 33%), fatigue (5/18, 27.8%), hyponatremia (4/18, 22.2%), and thrombocytopenia (4/18, 22.2%). Grade 3 TRAEs included hyperglycemia (5/18), lymphocytopenia (4/18), rash (2/18), weight loss (2/18), leukopenia (1/18), infusion-related reaction (1/18), nausea (1/18), and stomatitis (1/18). There was no TRAE leading to treatment permanent discontinuation and no grade 4/5 TRAE were observed. PK of WX390 in combination showed similar PK profile with the single agent. Among the 16 efficacy-evaluable patients with cervical (N=8), head and neck (N=5), and urothelial cancer (N=3), 5 patients (31.3%) previously received immune checkpoint inhibitors. 3 of 5 (60%) cervical cancer patients at RP2D and 2 of 5 head and neck cancer patient (40%) have achieved confirmed partial response (PR). In addition, 3 cervical patients who were treated with 0.7 or 0.9mg QD and 1of 3 urothelial carcer patients experienced tumor shrinkage (SD). The medium progression free survival (PFS) was 5.49 months (95% CI: 2.53, 6.37). Conclusions: WX390 in combination with Toripalimab had a manageable safety profile and encouraging antitumor effects in patients with advanced solid tumors. An RP2D of 1.1 mg qd of WX390 in combination was selected to be explored in further phase II study, which is ongoing in different tumor types. Clinical trial information: NCT06117566 .

A phase Ia, dose-escalation study of IMB071703 injection in patients (pts) with recurrent or metastatic, advanced solid tumors.

e14502 Background: IMB071703(XFab-α4-1BB/CD40L), a 4-1BB Fab and triCD40L fusion protein that activates dendritic cell and primes tumor-reactive T cells, mediates immune response, and further inhibits tumor development. We confirmed the expansion of antigen-specific T cells in various mouse models and potent tumor regression administrated by IMB071703 alone or in combination with gemcitabine in vivo, concomitant with improved tumor-reactive T-cell infiltration. IMB071703 showed no signs of liver toxicity at the dose levels up to 51 mg/kg in a repeated-dose study in non-human primates. Here, we describe initial data from a phase Ia study (CTR20230326). Methods: Eligible patients with recurrent or metastatic, advanced solid tumors were enrolled in this study. IMB071703 was administrated at escalating doses of 0.05, 0.15, 0.5,1.0 and 1.5 mg/kg intratumorally Q1W in Cycle 1 (C1:21days), and Q2W from Cycle 2 and subsequent cycles (Cn+1:28 days). Enrolled pts would first undergo DLT observative assessment (21 days). After pts were assessed safely during DLT observation, they would continue the scheduled dosage of IMB071703 until disease progression, intolerable toxicity or other reasons specified in the clinical protocol. The study objectives included the safety, tolerability, PK, pharmacodynamics, immunogenicity, and preliminary efficacy. Results: 7 pts with recurrent or metastatic, advanced solid tumors (median age 60 years, range 42-71; 4 male, 3 female; prior lines of therapy with range 1-6) were treated. Three dose levels, 0.05 mg/kg(n=1), 0.15 mg/kg(n=3), and 0.5mg/kg(n=3), had been evaluated. 1.0mg/kg dose escalation is ongoing. On cutoff date of 18 Dec. 2023, 1 pt is on the study and 6 pts had discontinued treatment. The reasons for discontinuation included confirmed disease progression (n=5) and other reason(n=1). 7 pts (100%) experienced treatment-emergent adverse events (TEAEs). 5 pts (71%) experienced treatment-related adverse events (TRAEs≥10%): Injection reaction (pain, fever, chill) (28%), fatigue (11%). All TRAEs were ≤grade 2. No DLT was observed. One death due to disease progression, as only a SAE, was identified to be unrelated. No objective response was observed in 6 evaluable pts. 1 pt was SD and 5 pts were PD. Pharmacodynamic data showed CD40 was occupied ≥50% in the 0.5 mg/kg level. The percentage of CTL (CD3+CD8+) in peripheral blood was increased (0.15mg/kg and 0.5mg/kg) Pharmacokinetic analysis also showed the mean half-life of IMB071703 was 2.45 hours in three dose levels. Biomarker analysis indicated 4-1BB up-regulation and PD-1 down-regulation was associated with the favorable response. Conclusions: IMB071703 Showed a good safety profile at the dose levels of 0.05 mg/kg, 0.15 mg/kg, and 0.5mg/kg. Both favorable tolerability and preliminary antitumor activity warrant further evaluation in patients with advanced malignancies. Clinical trial information: CTR20230326 .

A phase I/II open label, multicenter study to assess the safety, tolerability, pharmacokinetics, and efficacy of HB0028 in patients with advanced solid tumors.

2528 Background: HB0028 is a bifunctional fusion protein consisting of an anti-PD-L1 IgG1 single domain antibody and TGF-β RII receptor extracellular domain (TGFβRII-ECD). This is the first dose escalation and expansion phase I/II study to evaluate the safety and preliminary anti-tumor activity of HB0028 in advanced solid tumors. Methods: In the phase I portion of the study, the patients (pts) with advanced solid tumor were enrolled, and an accelerated titration followed by a standard 3+3 design was applied to dose escalation. The objectives were toxicity evaluation, maximum tolerable dose (MTD), and recommended phase 2 dose (RP2D). Eligible pts with advanced solid cancers of any histologic subtype, and ECOG performance status ≤ 1 were treated with HB0028 (0.3mg, 1mg, 3mg, 10mg, 20mg, Q3W), until unacceptable toxicity or disease progression. Radiologic tumor assessments (by RECIST v1.1) were performed every 6 weeks while on treatment. Results: 16 pts [12 females and 4 males; ECOG 0/1, 9/7; median age 52 years (range 36 – 60)] were enrolled in phase I (0.3 mg/kg [n = 1], 1 mg/kg [n = 3], 3 mg/kg [n = 3], 10 mg/kg [n = 3], 20 mg/kg [n = 6]). Median number of prior lines of systemic therapy was 2 (range 1-4). 8(50%) pts received and progressed upon prior anti-PD-1/L1 therapy. All pts had measurable metastatic disease. No DLT and Death occurred. MTD was not reached. As of DEC 25,2023, among 16 patients' safety data are evaluable for toxicity. Any grade treatment‐related adverse events (TRAEs) occurred in 15 subjects (93.8%), with 2 subjects (12.5%) reported with ≥ Grade 3 (G3 Anemia and G3 γ-glutamyltransferase). The most common TRAEs (all grades) were AST increased (n = 4, 25%), anemia (n = 7, 43.8%) and infusion-related response (n = 5, 31.3%). Two SAEs (G2 AST increased and G3 Neoplastic fevers) were reported, only AST increased was considered as possibly related to study drug, but recovered shortly. The efficacy data cutoff date of DEC 25,2023, 16 patients are evaluable for radiologic response. 1 subject with cervical cancer in HB0028 20 mg/kg group had a partial response (PR), 3 subjects (liver cancer, lung cancer, left submandibular gland cancer) had stable disease (SD) and 12 subjects had progressive disease (PD). The ORR per RECIST 1.1 by investigator was 6.25% (1/16; 95% CI, 0%-30.2%), and the DCR was 25% (4/16; 95% CI, 7.3%-52.4%). Durable clinical benefit (SD for > 32 weeks) was seen in 1 subject with malignant tumor in the left submandibular gland. To date, 2 responders are still on treatment. Conclusions: HB0028 was generally well tolerated, and therapy provided modest antitumor activity in patients with heavily pretreated advanced solid tumors. Based on these data, a phase II prospective clinical trial is being planned in specific cancer. Clinical trial information: NCT06223308 .

First-in-human study of ZG0895, a TLR8 selective agonist, as monotherapy in patients with advanced solid tumors.

e15103 Background: ZG0895 is a potent and novel Toll-like receptor (TLR) agonist that shows a highly selective activation of TLR8. It inhibits tumor growth by launching TLR8 downstream signal cascades, thus activating both innate and adaptive immune systems. We report preliminary results from a phase I, first-in-human, dose escalation study evaluating the safety, pharmacokinetics (PK) and antitumor activity of ZG0895 in patients with advanced solid tumors. Methods: Eligible patients previously treated with or intolerant to available standard systemic therapy(ies), received subcutaneous (s.c.) injection of ZG0895 weekly. If tolerated during the first treatment cycle (21 days per cycle), patients would continue weekly s.c. administrations of ZG0895 until disease progression, loss of clinical benefit, or development of unacceptable toxicity. Dose escalation scheme for ZG0895 was planned with eight dose levels (0.06, 0.18, 0.37, 0.75, 1.50, 2.25, 3.00, 3.75 mg/m2) according to an accelerated titration in the first two dose levels and the standard “3+3” design in the rest dose levels. Primary end points are the safety, tolerability, and recommended phase 2 dose (RP2D) of ZG0895. Secondary endpoints include overall response rate (ORR), disease control rate (DCR) and progression free survival (PFS) per the Response Evaluation Criteria in Solid Tumors version 1.1, as well as pharmacokinetics. Results: At data cut-off (December 25, 2023), 7 patients (5 males and 2 females), with the median age of 59 (range: 38-74) years old, received weekly s.c. injections of ZG0895 at the dose levels from 0.06 mg/m2 to 0.75 mg/m2 and completed the DLT observation period. Of the 7 patients, 4 (57.1%) received at least 3 lines of prior antineoplastic therapies, and 3 (42.9%) had exposed to PD-(L)1 inhibitors previously. No dose limiting toxicity events were reported. Five patients (71.4%) experienced grade 1 or 2 treatment-related adverse event (TRAE), and the most frequent events were injection site pain, hypertriglyceridaemia and proteinuria. None of patients experienced ≥grade 3 TRAE. Two patients experienced SAEs (intestinal obstruction and tumour haemorrhage), and both events were not related to ZG0895. The Cmax and AUC increased from 0.06 to 0.18 mg/m2 approximately in dose proportion. Conclusions: During the first 4 dose groups, ZG0895 was well tolerated in patients with advanced solid tumors. Phase I dose escalation of ZG0895 are underway in higher doses. Clinical trial information: NCT05877664 .

Evaluation of a predictive biomarker for antibody drug conjugates (ADCs).

3140 Background: Several ADCs are FDA-approved for patients with advanced solid tumors; dozens more are in trials. Predictive biomarkers are lacking, with ADC target expression alone performing poorly across ADCs/tumor types. We previously described the development of ADC Treatment Response Scores (ADC-TRS)—a tissue-based multivariate gene-expression test combining individual ADC target expression with proliferation and adhesion—with high correlation of per-ADC/tumor type biomarker frequency (TRS-High) with corresponding clinical trial ORRs for 9 ADCs (PO1-14-04; SABCS 2023). Here we evaluated ADC-TRS in two cohorts of patients treated with approved ADCs. Methods: Adults with advanced solid tumors from an observational trial (NCT03061305) treated with an ADC with TRS results from FFPE tissue (collected prior to 1st ADC treatment) were eligible; HER2+ patients previously treated with trastuzumab or with hormonal therapy treatment between sample collection/first ADC treatment were excluded. Kaiser Permanente Northern California (KPNC; limited to breast [BR] and bladder [BL] cancer) patients and non-KPNC patient (pan-solid tumor) cohorts were analyzed separately. We evaluated whether treatment-matched ADC-TRS status (High or Low) was significantly associated with overall survival (OS) after ADC treatment initiation by Cox proportional hazards models (adjusting for age, indication, and years since tissue collection). Additional analyses in the non-KPNC cohort evaluated whether proliferation/adhesion-related gene expression provided information on outcomes beyond ADC target expression only and predictive/prognostic effect. Results: Patients treated with an approved ADC were included in the non-KPNC (n=72; 5 ADCs/9 tumor types); most frequent sacituzumab govitecan/BR [43%]) and KPNC (n=127; 3 ADCs/two tumor types; most frequent enfortumab vedotin/BL[50%]) cohorts, respectively. In both cohorts, ADC TRS status was significantly associated with OS (High vs. Low, median OS 22.8 vs. 8.7 months [mo.], aHR 0.15, p=0.005, and median OS 15.3 vs. 8.3 mo., aHR 0.58, p=0.011, respectively). In the non-KP cohort, ADC-TRS significantly improved model fit for OS beyond target gene expression alone (likelihood ratio test [LRT] p=0.0008). A predictive biomarker effect was confirmed by lack of ADC-TRS status association with OS from systemic chemotherapy start in indication-matched patients not treated with an ADC (n=126, aHR 0.43-2.79, p=0.11-1.0 for the 9 individual TRS). In a 15,108 patient pan-tumor cohort (regardless of treatment), 26.7% were ADC-TRS High for at least 1 approved ADC outside approved indications. Conclusions: Results support ADC-TRS as a multivariate gene-expression-based biomarker that predicts ADC OS across tumor types and targets. More than 25% of all patients with advanced solid tumors have a greater likelihood of being responsive to one or more approved ADCs outside of approved indications.