Preliminary Clinical Efficacy Research Articles

ADU-1604, a novel CTLA-4 blocking antibody, to modulate pharmacodynamic markers in patients with PD1 relapse/refractory melanoma.

9552 Background: Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a negative regulator of T-cell responses, also known as an immune checkpoint. The clinical relevance of CTLA-4 blockade was demonstrated by the approval of ipilimumab for the treatment of melanoma, both in the adjuvant as well as metastatic settings. ADU-1604 is a humanized hIgG1 CTLA-4 antagonist antibody. ADU-1604 binds a unique epitope on CTLA-4 demonstrating, in contrast to ipilimumab full blockade of both CD80 and CD86 interactions. In vitro and in vivo ADU-1604 demonstrates at least as potent efficacy as compared to ipilimumab, was well tolerated in non-human primates and demonstrated enhanced immunogenicity against hepatitis B vaccine in non-human primates. Methods: This is a phase 1, first-in-human (FIH), two-part, open-label clinical trial of intravenous (IV) administration of ADU-1604 given as monotherapy in subjects with advanced-stage, relapsed/refractory melanoma who relapsed or were refractory to a prior anti-PD-1/PD-L1 therapy. Main endpoints are safety of ADU-1604 monotherapy, pharmacokinetics, pharmacodynamics (upregulation of ICOS and Ki-67 on circulation CD4+ T cells and ALC, CD4+ and CD8+ T cells) as well as preliminary clinical efficacy. 20 subjects received escalating doses of ADU-1604 IV (25, 75, 225, 450 mg flat dose) Q3W. In the dose expansion part up to 20 additional patients will be treated with 225 mg dose to confirm recommended Phase 2 dose (RP2D). Safety and preliminary efficacy of ADU-1604 monotherapy in PD1 relapsed/refractory melanoma patients will be evaluated. The study was initiated in June 2022. Results: ADU-1604 was demonstrated to have a typical pharmacokinetic behavior for a human IgG1 antibody and similar exposure was observed as described for ipilimumab. Administration of ADU-1604 in cycle 1 and 2 showed a dose-dependent modulation of ICOS and Ki-67 on circulating CD4+ T cells. Similarly, in cycles 3 and 4 a dose-dependent increase of ALC and CD4+ and CD8+ T cells was detected. Notably, no DLTs across the 25, 75, 225 and 450 mg dose level have occurred. Of the patients treated at 225 and 450 mg dose levels (N=6 at 225 mg and N=6 at 450 mg), two Grade 2 severe adverse events (both immune-related enterocolitis) and two Grade 3 AESIs (ALT elevation and immune-related gastritis) suggesting that ADU-1604 has a relatively mild safety profile. Two patients at 225 mg and one patient at 450 mg demonstrated clinical efficacy. Conclusions: ADU-1604 Phase 1 dose-escalation data indicates clinical activity in line with what has been observed with other CTLA-4 blocking antibodies. Importantly, no DLTs and very limited safety signals were reported during the study. Dose expansion at 225 mg dose is ongoing in subjects with advanced-stage, relapsed/refractory melanoma who relapsed or were refractory to a prior anti-PD-1/PD-L1 therapy. Clinical trial information: 2021-002623-38 .

Phase 1 study of ZV0203, a first in class pertuzumab ADC, in patients with HER2 positive advanced solid tumors.

e15004 Background: ZV0203, a first in class (FIC) pertuzumab antibody-drug conjugate (ADC), targets HER2 positive tumor cells with tubulin inhibitor DUO5 as its payload via a stable and protease-cleavable valine-citrulline linker. In preclinical studies, ZV0203 demonstrated superior antitumor activity compared to Kadcyla in multiple tumor cell line xenograft models with no noticeable toxicity. GLP toxicity studies indicated that ZV0203 was well tolerated with an estimated therapeutic index of 35. Methods: This was an open-label, multicenter, phase 1, dose-escalation study in patients (pts) with HER2+ advanced solid tumors. Primary objectives were safety, tolerability and RP2D. Secondary objectives included PK, immunogenicity and preliminary clinical efficacy. ZV0203 was administered intravenously Q3W on a 21-day cycle. An accelerated titration design was used for the 0.3 and 0.6 mg/kg doses, followed by a 3+3 design for 1.2, 1.8, 2.7 and 3.6 mg/kg dose levels. Results: As of January 18, 2024, 15 pts with solid tumors (breast [11], colorectal [2], gastric [1], lung [1]) were enrolled across doses of 0.3-3.6 mg/kg with a median age of 52 years old (range 35-65), of which 9 pts received prior HER2-targeted therapy (trastuzumab ± pertuzumab) and 14 pts completed 21-day DLT assessment (0.3 mg/kg and 0.6 mg/kg [1 each], 1.2 mg/kg, 1.8 mg/kg, 2.7 mg/kg and 3.6mg/kg [3 each]) with no DLT incidence. Treatment-related adverse events (TRAE) occurred in 14 (93.3%) pts. The most frequent TRAEs were corneal epitheliopathy [9], elevated liver enzymes [6], dry eyes [6], neutropenia [4], anemia [4], leukopenia [3], and proteinuria [3], and most were grade 1-2 in severity. 5 pts experienced grade 3 TRAEs: lymphocytopenia (1.8mg/kg [1]) , corneal epitheliopathy (3.6 mg/kg [1]) and blurred vision (2.7 mg/kg [2], 3.6 mg/kg [1]), which were manageable during treatment. No unexpected safety signals were reported. TRAEs led to 13.3% (2/15) treatment discontinuation. Among 14 pts evaluated, 5 pts achieved a best tumor response of PR; 4 pts had SD; 1 pt had Non-CR/Non-PD per RECIST v1.1. Thus, disease control rate was 71.4% (10/14). PK results demonstrated that the PK profile of total antibody was similar to that of ZV0203 ADC, whose systematic exposure increased in a dose-dependent manner and remained stable after repeated administration. Concentration of DUO5 remained scarce, suggesting good stability of ZV0203. Conclusions: ZV0203 was well tolerated and showed clinically encouraging anti-tumor activity in heavily pretreated pts with HER2 positive cancer. Clinical trial information: NCT05423977 .

Efficacy and safety of lenvatinib plus durvalumab combined with hepatic arterial infusion chemotherapy for unresectable intrahepatic cholangiocarcinoma.

e16184 Background: The prognosis for unresectable intrahepatic cholangiocarcinoma (ICC) is poor and the efficacy of traditional chemotherapy remains unsatisfactory. Hepatic arterial infusion chemotherapy (HAIC) with oxaliplatin, leucovorin, and 5-fluorouracil (FOLFOX) is effective in patients with unresectable ICC. In this study, we determined the preliminary clinical efficacy and safety of lenvatinib plus durvalumab combined with FOLFOX-HAIC in patients with untreated, unresectable ICC. Methods: Between July 2021 and July 2023, patients with unresectable ICC who initially received lenvatinib plus durvalumab combined with FOLFOX-HAIC at the Sun Yat-Sen University Cancer Center (SYSUCC) were retrospectively reviewed for eligibility. Efficacy was evaluated by tumor response rate and survival, and safety was assessed by the frequency of key adverse events (AEs). Results: A total of 28 eligible patients were enrolled. The objective response rates (ORRs) based on mRECIST and RECIST 1.1 criteria were 65.2% and 39.1%, respectively. The median OS was 17.9 months (95% CI, 5.7–30.1) and the median PFS was 11.9 months (95% CI, 6.7–17.1). Most patients (92.9%) experienced adverse events (AEs), whereas 46.5% (13/28) experienced grade 3 or 4 AEs. Conclusions: Lenvatinib plus durvalumab combined with FOLFOX-HAIC showed promising antitumor activity and manageable AEs in patients with treatment-naive unresectable ICC. This regimen may be suitable as a novel first-line treatment option for this patient population.

Petosemtamab (MCLA-158) with pembrolizumab as first-line (1L) treatment of recurrent/metastatic (r/m) head and neck squamous cell carcinoma (HNSCC): Phase 2 study.

6014 Background: EGFR is a known oncogenic driver in HNSCC, and the leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) is a receptor expressed on cancer stem cells, including in HNSCC. Petosemtamab is a human, common light chain, IgG1 bispecific antibody with ADCC-enhanced activity, targeting EGFR and LGR5. In the dose escalation part of a phase 1/2 study, the recommended phase 2 dose (RP2D) was determined to be 1500 mg every 2 weeks (Q2W). Interim data of petosemtamab monotherapy at the RP2D in 2L/3L HNSCC led to a 37.2% overall response rate (ORR; per investigator) with 6.0 months (mo) median duration of response (DOR) [Cohen, Cancer Research 2023]. Petosemtamab (RP2D) with pembrolizumab (400 mg Q6W) is being investigated in an expansion cohort of the ongoing phase 2 study (NCT03526835) in 1L HNSCC. Methods: Primary endpoints are safety and investigator-assessed ORR (RECIST v1.1). Secondary endpoints include DOR, progression-free survival (per investigator), and overall survival. Key eligibility criteria were r/m HNSCC with no prior systemic therapy, PD-L1 combined positive score ≥1, ECOG PS 0–1, measurable disease, and primary tumor location in oropharynx (regardless of p16 status), oral cavity, hypopharynx, or larynx. Results: No dose-limiting toxicities were observed in the safety run-in. As of a November 6, 2023 data cutoff, 26 pts were treated (24 continuing therapy at the data cutoff) and median follow-up was 1.35 mo. Median age was 62.5 years (range 23–80), ECOG PS 0/1 in 10/16 pts, and 65.4% were male. The most frequent primary tumor locations were oropharynx (34.6%), oral cavity (19.2%), and hypopharynx (19.2%). A median of 2 cycles (range 1–8) were administered. The combination was well tolerated and no significant overlapping toxicities were observed. Treatment-emergent adverse events (AEs) were reported in 26 pts, and most were Grade (G) 1 or 2 in severity (no G4–5 were observed). The most frequent AEs (all Gs/G3) were acneiform dermatitis (30.8%/0%), asthenia (26.9%/0%), and rash (26.9%/0%). Infusion-related reactions (composite term) were reported in 26.9% (all Gs) and 3.8% (G3) of pts, all occurred during the first infusion and resolved. Among 10 pts evaluable for efficacy (≥2 cycles and ≥1 post-baseline scan, or early progressive disease), there were 1 confirmed complete response, 2 confirmed and 3 unconfirmed partial responses (2 confirmed after data cutoff), 3 stable disease, and 1 progressive disease; with all 6 responders on treatment at data cutoff. Enrollment has been completed and updated data will be presented. Conclusions: Petosemtamab, a first-in-class EGFR x LGR5 bispecific antibody, in combination with pembrolizumab demonstrates a well-tolerated safety profile and promising preliminary clinical efficacy as 1L treatment for pts with r/m HNSCC. Clinical trial information: NCT03526835 .

Abstract PR005: Final results from a Phase I trial of intravesical chemoimmunotherapy with gemcitabine and Bacillus Calmette-Guérin (BCG) for patients with BCG-exposed high-grade non-muscle invasive bladder cancer

Abstract Background: Although retreatment with BCG is considered standard of care for patients with BCG-exposed high-grade (HG) non-muscle invasive bladder cancer (NMIBC), less than 50% of patients are expected to respond. As such, the ability to augment the efficacy of BCG in this population remains a critical unmet need. Preclinical studies suggest that intravesical gemcitabine (Gem) may demonstrate synergistic efficacy with BCG by favorably altering the tumor microenvironment. We therefore sought to evaluate the safety, tolerability, and preliminary clinical efficacy of GemBCG in patients with BCG-exposed HG NMIBC through an IRB-approved Phase I/II clinical trial. Methods: Patients with BCG-exposed papillary HG NMIBC (Ta/T1) with or without carcinoma in situ (CIS) that recurred within 24 months of BCG therapy were eligible for this trial. Exclusion criteria included BCG-unresponsive disease, contraindication to BCG therapy, or ureteral/urethral urothelial disease. Consenting patients underwent complete transurethral resection of bladder tumors followed by intravesical Gem twice weekly (weeks 1, 4, 7, 10) for a total of 8 doses. Dose escalation of Gem was performed from 50-2000 mg using a Bayesian modified continual reassessment method. Intravesical Gem instillations alternated with weekly intravesical TICE BCG therapy (weeks 2, 3, 5, 6, 8, 9) for a total of 6 doses fixed at 50 mg followed by maintenance BCG in responders. Complete response (CR) rates and progression to muscle-invasive bladder cancer (MIBC) or cystectomy were evaluated at 12 months of follow up in the Phase I cohort. Results: A total of 25 patients was enrolled (median age 70 years [IQR 64-75]), all of which have at least 12 months of follow up. Of these, 88% (22/25) were male. Median duration of bladder cancer treatment prior to enrollment was 385 days (IQR 173-634), and 28% (7/25) previously received either maintenance therapy (3/25) or >1 induction courses of BCG (4/25). Based on centralized pathology review, a total of 68% had CIS ± papillary disease (8 HGTa, 5 HGT1, and 4 Tis), while 32% had papillary-only disease (4 HGTa and 4 HGT1). No dose limiting toxicities were observed, and 14/25 patients were treated at the maximum tolerated dose. The treatment was well tolerated with no patient experiencing treatment-related Grade 3-5 toxicity. CR rates at 6 months and 12 months were 96% (24/25) and 92% (23/25), respectively. No progression to MIBC or radical cystectomy was observed. Conclusion: Combination GemBCG in BCG-exposed HG NMIBC is well tolerated and appears to provide excellent cancer control. Based on these encouraging findings and the ongoing phase II portion (NCT04179162), a prospective randomized controlled trial comparing GemBCG to BCG alone for BCG-exposed NMIBC is planned through the National Clinical Trial Network (Alliance A032303). Citation Format: Syed M. Alam, Christopher D. Gaffney, Jessica Lavery, Merve Basar, Neeta D'Souza, Christian Hernandez, Melissa McCarter, Patricia Moran, Kristen Stasi, Kara Worth, Daniel Sjoberg, Guido Dalbagni, Timothy Donahue, Sherri Donat, Dean Bajorin, Bernard H. Bochner, Alvin Goh, Judy Sarungbam, Hikmat Al-Ahmadie, Eugene J. Pietzak. Final results from a Phase I trial of intravesical chemoimmunotherapy with gemcitabine and Bacillus Calmette-Guérin (BCG) for patients with BCG-exposed high-grade non-muscle invasive bladder cancer [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr PR005.

Efficacy and safety of lenvatinib plus durvalumab combined with hepatic arterial infusion chemotherapy for unresectable intrahepatic cholangiocarcinoma.

The prognosis for unresectable intrahepatic cholangiocarcinoma (ICC) is poor and the efficacy of traditional chemotherapy remains unsatisfactory. Hepatic arterial infusion chemotherapy (HAIC) with oxaliplatin, leucovorin, and 5-fluorouracil (FOLFOX) is effective in patients with unresectable ICC. In this study, we determined the preliminary clinical efficacy and safety of lenvatinib plus durvalumab combined with FOLFOX-HAIC in patients with untreated, unresectable ICC. Between July 2021 and July 2023, patients with unresectable ICC who initially received lenvatinib plus durvalumab combined with FOLFOX-HAIC at the Sun Yat-Sen University Cancer Center (SYSUCC) were reviewed for eligibility. Efficacy was evaluated by tumor response rate and survival, and safety was assessed by the frequency of key adverse events (AEs). A total of 28 eligible patients were enrolled. The objective response rates (ORRs) based on mRECIST and RECIST 1.1 criteria were 65.2% and 39.1%, respectively. The median OS was 17.9 months (95% CI, 5.7-30.1) and the median PFS was 11.9 months (95% CI, 6.7-17.1). Most patients (92.9%) experienced adverse events (AEs), whereas 46.5% (13/28) experienced grade 3 or 4 AEs. Lenvatinib plus durvalumab combined with FOLFOX-HAIC showed promising antitumor activity and manageable AEs in patients with treatment-naive unresectable ICC. This regimen may be suitable as a novel first-line treatment option for this patient population.

Abstract PO1-24-04: Gedatolisib, a pan-PI3K/mTOR inhibitor, shows superior potency and efficacy relative to other PI3K/AKT/mTOR pathway inhibitors in breast cancer models

Abstract Background: The PI3K, AKT, and mTOR (PAM) pathway is frequently activated in breast cancer (BC). Current standard-of-care therapy options for patients with advanced BC (ABC) include PAM inhibitors (PAMi), such as everolimus and alpelisib, and hormonal therapy, such as letrozole and fulvestrant. Most PAMi selectively inhibit one or only a few PAM pathway components, which can lead to drug resistance. To minimize drug resistance, a more comprehensive inhibition of the multiple PI3K isoforms and downstream mTOR complexes may be required. We hypothesized that gedatolisib, which potently inhibits all Class I PI3K isoforms, as well as mTORC1 and mTORC2, can be more effective in BC cells than a PAMi targeting single PAM pathway components. Methods: A panel of BC cell lines with mutated or non-mutated PAM pathway genes (PIK3CA, PTEN, AKT) were evaluated for their sensitivity to gedatolisib and other PAMi (PI3K-α: alpelisib; AKT: capivasertib; mTORC1: everolimus; pan-PI3K/mTOR: gedatolisib). Cell viability, growth rate inhibition, and cell death were evaluated by luciferase- and fluorescence-based assays, both in monolayer cultures and three-dimensional (3D) cultures on reconstituted basement membrane. Flow cytometry analytical assays were conducted to assess DNA synthesis (EdU incorporation), protein synthesis (OPP incorporation), and PAM pathway activity (RPS6 and 4EBP1 phosphorylation). BC xenograft studies evaluating gedatolisib in vivo were also performed. Results: Gedatolisib strongly inhibited PAM pathway activity and reduced cell viability and growth rate in the cell lines tested. Compared to the other PAMi, gedatolisib exhibited more potent and efficacious anti-proliferative and cytotoxic effects, regardless of the cell lines’ PI3K pathway mutational status. Gedatolisib effects were confirmed in 3D culture on reconstituted basement membrane, where gedatolisib inhibited tumor cell spheroid growth and induced regression. Mechanistically, gedatolisib decreased both DNA and protein synthesis more effectively than the other PAMi tested. Gedatolisib also exerted superior anti-proliferative and cytotoxic effects relative to the other PAMi tested in estrogen receptor-positive BC cell lines concomitantly treated with fulvestrant. BC xenografts confirmed growth inhibitory effects of gedatolisib in vivo. Conclusions: The pan-PI3K/mTOR inhibitor, gedatolisib, may more effectively address potential drug resistance mechanisms associated with narrowly targeted PAM inhibitors. Gedatolisib has previously demonstrated promising preliminary clinical efficacy and safety data in ABC in combination with hormonal therapy. A Phase 3 study (VIKTORIA-1) evaluating gedatolisib plus fulvestrant with and without palbociclib is underway in patients with ABC. Citation Format: Stefano Rossetti, Aaron Broege, Adrish Sen, Salmaan Khan, Ian MacNeil, Jhomary Molden, Igor Gorbatchevsky, Brian F. Sullivan, Lance Laing. Gedatolisib, a pan-PI3K/mTOR inhibitor, shows superior potency and efficacy relative to other PI3K/AKT/mTOR pathway inhibitors in breast cancer models [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-24-04.

Abstract CT142: Phase 1 study of BPI-23314, a novel BET inhibitor and degrader, in advanced myeloid leukemia (AML)

Abstract Background: The novel small-molecule inhibitor and degrader, BPI-23314, targeting of the bromodomain and extra-terminal domain (BET) family proteins, BPI-23314, has been showndemonstrated promising preclinical efficacy in hematologic malignancies. This Phase 1 study aims to evaluate the safety, pharmacokinetics, and preliminary efficacy of BPI-23314 monotherapy in patients with relapsed or refractory acute myeloid leukemia (R/R AML). Methods: This ongoing phase 1 study of BPI-23314 enrolled adult patients with R/R AML. Dose escalation was conducted using a standard 3+3 design, followed by additional expansion cohorts to further assess safety and preliminary efficacy. BPI-23314 tablets were administered orally once daily (QD) or twice daily (BID) in consecutive 21-day cycles. The key endpoints included determining the recommended Phase 2 dose (RP2D), safety, pharmacokinetics, and preliminary efficacy. Results: As of July 31, 2022, a total of 22 patients diagnosed with R/R AML were treated with BPI-23314 at seven different dose levels, ranging from 5 to 60 mg QD or 40 to 50 mg BID. The median age of the patients was 48 years (range: 19-68 years), and the median treatment duration was 6 weeks (range: 2-9 weeks). The median number of prior therapy lines was 3 (range: 1-4), with 15 (68.2%) being refractory to last line of therapy. Due to the high incidence of grade≥3 anemia, thrombocytopenia, and neutropenia among the patients at baseline, most treatment-emergent adverse events (TEAE) of hematologic toxicities were mainly correlated with disease progression. Only one patient experienced grade 3 treatment-related adverse events (TRAE) comprising anemia (4.5%) and neutropenia (4.5%). Non-hematologic TRAEs were predominantly of grade 1-2. The most common TRAEs (≥10%) were gastrointestinal reactions (10/22, 45.5%), hypertriglyceridemia (6/22, 27.3%), hyperbilirubinemia (4/22, 18.2%), elevated alanine aminotransferase levels (3/22, 13.6%), and increased gamma-glutamyl transferase levels (3/22, 13.6%). Gastrointestinal reactions characterized by nausea and/or diarrhea were the most commonly reported toxicities. The most common TEAEs associated with disease progression were infection and bleeding. No dose-limiting toxicity or treatment-related deaths were reported during the study period, and the maximum tolerated dose was not reached. Among the evaluable responses in all dose levels for R/R AML patients (n=21), one patient achieved complete response (CR) at a dosage of 40 mg BID while three patients maintained stable disease (SD) across various dosages, including QD at 60 mg and BID at both 40 mg and 50 mg. Furthermore, BPI-23314 demonstrated moderate elimination kinetics, with a plasma half-life ranging from 8.6 to 23.3 hours, while exhibiting dose-proportional exposure. Conclusion: BPI-23314 monotherapy exhibited preliminary clinical efficacy with manageable adverse events in patients with R/R AML. The study is ongoing. The satisfactory pharmacokinetic attribute and outstanding safety profile of BPI-23314 provide compelling rationales for further exploration of its therapeutic potential. Citation Format: Mingyuan Sun, Xiangyu Jin, Jing Guo, Xiaoyun Liu, Yan Xu, Hong Lan, Jiabing Wang, Jiangnan Zhen, Jing Yang, Lieming Ding, Junyuan Qi. Phase 1 study of BPI-23314, a novel BET inhibitor and degrader, in advanced myeloid leukemia (AML) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT142.

B7-H3 Inhibitors in Oncology Clinical Trials: A Review.

B7-H3 is a transmembrane receptor highly prevalent on malignant cells and plays an important role in adaptive immunity that is not fully elucidated. Targeted B7-H3 inhibitors, including antibody-drug conjugates, radioimmunotherapy, and monoclonal antibodies, are a new class of antineoplastic agents showing promising preliminary clinical efficacy, observed with several of these agents against multiple tumor types. Particularly promising treatments are enoblituzumab for prostate cancer, 131I-omburtamab for central nervous system malignancies, and HS-20093 for small-cell lung cancer but further studies are warranted. There are clinical trials on the horizon that have not yet enrolled patients examining chimeric antigen receptor T-cell therapies, bi- and tri-specific killer engagers, and dual-affinity retargeting proteins. These data will be telling of the efficacy of B7-H3 inhibitors in both hematologic and solid malignancies. This study aimed to compile available results of B7-H3 inhibitors in oncology clinical trials.

Psilocybin-assisted therapy for severe alcohol use disorder: protocol for a double-blind, randomized, placebo-controlled, 7-month parallel-group phase II superiority trial

BackgroundA significant number of individuals with alcohol use disorder remain unresponsive to currently available treatments, which calls for the development of new alternatives. In parallel, psilocybin-assisted therapy for alcohol use disorder has recently yielded promising preliminary results. Building on extant findings, the proposed study is set to evaluate the feasibility and preliminary clinical efficacy of psilocybin-assisted therapy when incorporated as an auxiliary intervention during inpatient rehabilitation for severe alcohol use disorder. Moreover, it intends to pinpoint the modifications in the two core neurocognitive systems underscored by dual-process models of addiction.MethodsIn this double-blind, randomized, placebo-controlled, 7-month parallel-group phase II superiority trial, 62 participants aged 21–64 years will be enrolled to undergo psilocybin-assisted therapy as part of a 4-week inpatient rehabilitation for severe alcohol use disorder. The experimental group will receive a high dose of psilocybin (30 mg), whereas the control group will receive an active placebo dose of psilocybin (5 mg), both within the context of a brief standardized psychotherapeutic intervention drawing from key elements of acceptance and commitment therapy. The primary clinical outcome is the between-group difference regarding the change in percentage of heavy drinking days from baseline to four weeks posthospital discharge, while safety and feasibility metrics will also be reported as primary outcomes. Key secondary assessments include between-group differences in terms of changes in (1) drinking behavior parameters up to six months posthospital discharge, (2) symptoms of depression, anxiety, trauma, and global functioning, (3) neuroplasticity and key neurocognitive mechanisms associated with addiction, and (4) psychological processes and alcohol-related parameters.DiscussionThe discussion outlines issues that might arise from our design.Trial registrationEudraCT 2022-002369-14 and NCT06160232.

A mixed-methods study to evaluate the feasibility and preliminary efficacy of delivering the optimal health program (OHP) for youth at clinical high risk (CHR) for psychosis: A study protocol.

Individuals with clinical high risk (CHR) for psychosis experience significant distress, impaired general functioning and a high lifetime risk of self-harm and attempted suicide. The CHR period is an important phase in an individual's mental health where appropriate interventions may reduce the risk of progression to several negative outcomes, including the development of schizophrenia. Given that up to 80% of individuals with CHR have another diagnosable mental illness and almost half experience poor psychosocial functioning, developing interventions that address psychosocial functioning in young people with CHR is of great importance. This mixed-methods study aims to employ qualitative and quantitative methods to adapt an evidence-based comprehensive psychosocial and mental health self-efficacy program, the Optimal Health Program (OHP), and evaluate the feasibility, acceptability and preliminary clinical efficacy in young people with CHR. We aim to recruit 30 CHR participants (age 16-29 years) in a single-arm 12-week exploratory clinical trial. Feasibility metrics will include recruitment, retention, and data completion rates. Acceptability will be informed by the Client Satisfaction Questionnaire. Clinical assessments (psychosis spectrum symptoms, depression, and anxiety), functional measures, and cognitive outcomes will be completed at study entry and repeated post-intervention at 12-weeks. We will run pre-post test data analysis to examine changes following engagement in the OHP intervention. Qualitative interviews will be conducted post-intervention to further evaluate the acceptability of the intervention and the trial design, and will be analyzed using thematic analysis. OHP may enhance the long-term mental health, well-being and functioning of CHR youth. However, the intervention must first be adapted to a CHR population; then, the feasibility and preliminary efficacy of delivering an intervention tailored around the varied needs of the CHR group must be established before a larger-scale appropriately powered study is pursued. Trial registration: The trial is registered with ClinicalTrials.gov NCT05757128.

AsCas12a Gene Editing of HBG1/2 Promoters with EDIT-301 Results in Rapid and Sustained Normalization of Hemoglobin and Increased Fetal Hemoglobin in Patients with Severe Sickle Cell Disease and Transfusion-Dependent Beta-Thalassemia

Background: Sickle cell disease (SCD) and transfusion-dependent β-thalassemia (TDT) are hereditary blood disorders caused by mutations in the β-globin gene. Clinical evidence has demonstrated that increased fetal hemoglobin (HbF, α2γ2) can reduce or eliminate SCD and TDT complications. EDIT-301, an investigational gene-edited autologous hematopoietic stem cell medicine, has a unique genomic modification that mimics naturally occurring mutations of hereditary persistence of fetal hemoglobin in the γ-globin gene ( HBG1/2) promoters. These mutations reactivate γ-globin expression and increase HbF production. EDIT-301 is manufactured with a highly efficient and specific, proprietary gene editing nuclease, AsCas12a. In preclinical studies, edited CD34 + cells from patients with SCD or TDT increased HbF production in red blood cells (RBCs) sufficient for a therapeutic effect, including reduced sickling (SCD) and improved erythropoiesis (TDT). Aim: RUBY (NCT04853576) and EdiThal (NCT05444894) are Phase I/II, multicenter, open-label, single-arm studies evaluating the safety, efficacy, and tolerability of EDIT-301 in patients with severe SCD and TDT, respectively. As of June 28, 2023, 7 SCD patients and 2 TDT patients have received EDIT-301 treatment. Preliminary clinical efficacy and safety data are reported. Methods: Patients aged 18-50 years with severe SCD (defined as ≥2 severe vaso-occlusive events [VOEs] per year in the 2 years prior to informed consent [IC]) and patients aged 18-35 years with TDT (defined as at least 100 mL/kg/year or 10 U/year of packed RBC transfusions in the 2 years prior to IC) were eligible to enroll in RUBY and EdiThal, respectively. Autologous CD34 + hematopoietic stem and progenitor cells collected by apheresis after plerixafor (RUBY) or plerixafor + filgrastim (EdiThal) mobilization were edited at the HBG1/2 promoters with AsCas12a. After myeloablative conditioning with busulfan, patients received a single infusion of EDIT-301 (a minimum of 3 × 10 6 CD34 + cells/kg), and were monitored for engraftment, total hemoglobin (Hb), HbF, mean HbF concentration/F-cell (MCH-F/F-cell), percentage of F-cells, markers of hemolysis, transfusion requirement, VOEs (SCD only), and adverse events (AEs) for 24 months. Results: Based on a data cut of June 28, 2023, Patients 1-4 with SCD were 12-, 9-, 4-, and 4-months post-EDIT-301 infusion, respectively. Patients 5-7 with SCD were <1-month post-EDIT-301 infusion. Patients 1-2 with TDT were 3- and <1-months post-EDIT-301 infusion, respectively. Neutrophil and platelet engraftment were achieved after a mean (range) of 25 (23-29) and 27 (19-37) days in Patients 1-4 with SCD and on Day 23 and 26 in Patient 1 with TDT, respectively. There were no VOEs in SCD patients post-EDIT-301 infusion, compared with a mean (range) of 4.2 (3.0-5.5) VOEs/year in the 2 years before enrollment (n=6). Following EDIT-301 infusion, Hb levels rapidly increased to 14.2 (12.4-15.7) g/dL by Month 4 (n=4), reaching the normal physiological range, from a mean (range) of 10.5 (8.5-11.9) g/dL at baseline (n=5). By Month 4, the mean (range) HbF concentration was 6.8 (5.7-7.6) g/dL and HbF was >40% (n=4); Patients 3 and 4 had >50% HbF. Percentage of F-cells and MCH-F/F-cell also increased. Key markers of hemolysis improved or normalized in all patients with SCD. Patient 1 with TDT had a HbF concentration of 7.2 g/dL by Month 3, stopped receiving RBC transfusions 20 days after EDIT-301 infusion, and remained transfusion free through the 3-month period. Patient 2 with TDT also showed early improvements. The safety profile of EDIT-301 in both SCD and TDT was consistent with myeloablative conditioning with busulfan. No serious AEs were reported after EDIT-301 infusion. Conclusion: These data demonstrated successful engraftment, a rapid and sustained normalization of Hb as early as 4 months after infusion, an increase in HbF and percentage of F-cells, resolution of VOEs (SCD) and transfusion independence (TDT). In addition, there were improvements in key markers of hemolysis (SCD) and a favorable safety profile in EDIT-301-treated patients. EDIT-301 treatment showed promising results for the first clinical use of AsCas12a in both SCD and TDT patients after gene editing of the γ-globin gene ( HBG1/2) promoters. These findings support further investigation of EDIT-301 in the RUBY and EdiThal trials. Updated data with additional outcomes will be presented.

GB261, an Fc-Function Enabled and CD3 Affinity De-Tuned CD20/CD3 Bispecific Antibody, Demonstrated a Highly Advantageous Safety/Efficacy Balance in an Ongoing First-in-Human Dose-Escalation Study in Patients with Relapsed/Refractory Non-Hodgkin Lymphoma

Introduction: GB261 is a novel and highly differentiated CD20/CD3 bispecific T cell engager antibody computationally designed to maintain Fc effector function, i.e., antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC) to broaden the mechanisms of action (MOA) for tumor cell killing. Furthermore, the “imbalanced” design of GB261 integrates de-tuned CD3 binding to reduce CRS incidence and improve safety features of the Fc effector function. Extensive pre-clinical studies have shown that GB261 has a highly advantageous safety/efficacy balance.Here, we present the preliminary clinical safety and efficacy results of an ongoing phase I/II study for GB261 (NCT04923048). Methods: This is an open-label, multicenter (China and Australia), dose-escalation/expansion phase 1/2 study of GB261 to evaluate the safety, tolerability and efficacy in patients with Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma(B-NHL) and Chronic Lymphocytic Leukemia (CLL). Adult patients were eligible when they have CD20+ r/r B-NHL or CLL with no available standard of care treatments, adequate organ function, and no CNS involvement or other CNS disease, infections or other active/serious medical issues that may affect compliance or interpretation of results. GB261 was administered in 21-day cycles, weekly (QW) for the first 6 doses followed by every 3 weeks (Q3W) until disease progression, or other situation defined in protocol. Response assessment was based on Lugano 2014 and LYRIC 2016 criteria. Results: As of June 17, 2023, 47 r/r B-NHL patients (DLBCL:76.6%; FL:23.4%) were enrolled at flat or step-up doses of GB261 ranging from 1mg to 300 mg. Median age was 60.0 years (range: 28, 81), 55.3% of patients were male. Median prior lines of therapy were 3 (range: 1, 10). 78.7% of patients were refractory to any anti-CD20 therapy, 70.2% refractory to their last systemic therapy. Median time since last prior therapy to first study treatment was 1.9 months. In efficacy evaluable patients (n=22) from 3mg to 100mg, with at least 75% dose exposure before the first radiographic assessment, the median duration of study follow-up was 4.5 months (95%CI: 4.0, 7.4). The overall response rate (ORR) was 73% (16/22), and complete response rate (CRR) was 45.5% (10/22). ORR and CRR were 100% and 100% in 3mg, 56% and 22% in 10mg, 67% and 33% in 30mg. At 100mg dose, there were 5 evaluable patients, with ORR 100% (5/5), CRR 80% (4/5) and PR (20%, 1/5; mosunetuzumab-refractory rrDLBCL patient). Median time to response (TTR) was 1.3 months (95%CI: 1.2, 1.5), the same as median time to CR. Median duration of response (DOR) was not reached. In safety evaluable patients (n=47), the median duration of study follow-up was 4.1 months (95%CI: 2.9, 5.3). Treatment-emergent adverse events (TEAEs) were 95.7%, treatment-related adverse events were 85.1%. The most common TEAEs were COVID-19 infection (40.4%; grade 1 or 2: 27.6%; grade >=3: 12.8%) and neutropenia (31.9%; grade 1or 2: 14.9%; grade >=3: 17.0%). AE related treatment discontinuation and death were reported in 2 patients, which were all due to COVID-19 pneumonia. CRS occurred in 12.8% (6/47) patients, was mild and transient. CRS in 100mg were 14.3% (2/14). All cases of CRS were grade 1 (8.5%, 4/47) or 2 (4.3%, 2/47), no grade 3 (Lee et al., ASTCT criteria), no interruptions of treatment, and no administration of Tocilizumab. The median duration of CRS was 7 hours. No ICANS were reported. The PK profile of GB261 appeared to be linear across dose ranges tested (1mg-100mg). Effective half-life appeared to be 2-3 weeks which supports every 3-4 weeks dosing. Conclusion: GB261, a novel and highly differentiated CD20/CD3 bispecific antibody, is the first clinical stage Fc+ CD20/CD3 T cell engager. In heavily pretreated B-NHL patients, GB261 showed a highly advantageous safety/efficacy balance, consistent with the MOA. The safety profile is excellent especially for the CRS which is very mild, transient and less frequent compare with other CD20/CD3 bispecific antibodies. The response after GB261 treatment was early, deep and durable. At the 100mg dose level, 80% of patients achieved CR and with favorable safety. Additionally, clinical benefit seen in other CD20/CD3 bispecific antibody failed patients provides clinical support to the unique and differentiated MOA of GB261.

Feasibility and Preliminary Behavioral and Clinical Efficacy of a Diabetes Education Chatbot Pilot Among Adults With Type 2 Diabetes.

Diabetes self-management education and support (DSMES) improves diabetes outcomes yet remains consistently underutilized. Chatbot technology offers the potential to increase access to and engagement in DSMES. Evidence supporting the case for chatbot uptake and efficacy in people with diabetes (PWD) is needed. A diabetes education and support chatbot was deployed in a regional health care system. Adults with type 2 diabetes with an A1C of 8.0% to 8.9% and/or having recently completed a 12-week diabetes care management program were enrolled in a pilot program. Weekly chats included three elements: knowledge assessment, limited self-reporting of blood glucose data and medication taking behaviors, and education content (short videos and printable materials). A clinician facing dashboard identified need for escalation via flags based on participant responses. Data were collected to assess satisfaction, engagement, and preliminary glycemic outcomes. Over 16 months, 150 PWD (majority above 50 years of age, female, and African American) were enrolled. The unenrollment rate was 5%. Most escalation flags (N = 128) were for hypoglycemia (41%), hyperglycemia (32%), and medication issues (11%). Overall satisfaction was high for chat content, length, and frequency, and 87% reported increased self-care confidence. Enrollees completing more than one chat had a mean drop in A1C of -1.04%, whereas those completing one chat or less had a mean increase in A1C of +0.09% (P = .008). This diabetes education chatbot pilot demonstrated PWD acceptability, satisfaction, and engagement plus preliminary evidence of self-care confidence and A1C improvement. Further efforts are needed to validate these promising early findings.

Early safety and efficacy from a phase I clinical study of TWP-101, a novel CD137 agonist antibody, in patients with advanced melanoma and urothelial carcinoma.

9530 Background: CD137 plays the roles as a potent co-stimulator of both adaptive and innate immune cells, being an attractive target for cancer immunotherapy. TWP-101 is a fully humanized agonistic anti-CD137 monoclonal IgG4 antibody, targeting a novel epitope of CD137 with a unique mechanism of actions as a CD137 agonist but not CD137 ligand antagonist. The phase I study of TWP-101 in patient (pt)s with advanced melanoma and urothelial carcinoma was initiated (NCT04871334). Methods: Enrolled pts were advanced melanoma refractory to standard therapy. Dose-escalation includes accelerated titration (0.01 and 0.03mg/kg) and conventional Fibonacci 3+3 dose levels (0.1, 0.3, 1.0 and 3.0 mg/kg). TWP-101 was administered intravenously every Q2W until confirmed progressive disease, unacceptable toxicity or withdrawal of consent. The primary objectives were to define the safety profile, to determine the maximum tolerated dose and RP2D of TWP-101. Secondary objectives were to evaluate pharmacokinetics (PK), immunogenicity and preliminary clinical efficacy. Exploratory objectives were to determine pharmacodynamics (PD) biomarkers. Results: From Feb 2021 to Mar 2022,13 melanoma pts (median age 54 years, range 39-73; 6 men, 7 women; median 2 prior lines of therapy, range 1-6; 12 with prior immunotherapy) were treated. The following five dose levels had been evaluated from 0.01 to 1.0 mg/kg. 3mg/kg dose escalation is ongoing, no MTD has been reached. The median treatment time was 16 wks. (range 2-59). On cutoff date of October 31, 2022, 13 pts discontinued treatment due to progression disease (n = 12) and protocol deviation (n = 1). No DLTs were observed. 9 pts (69.2%) experienced treatment-related adverse events (TRAE). The most common TRAEs (≥10%) were neutropenia (23.1%), leukopenia (15.4%), hypertriglyceridemia (15.4%), anemia (15.4%), hyponatremia (15.4%). 1 pt experienced grade 3-4 TRAEs: hyponatremia, Asthenia and reduced appetite. In all TRAEs, one grade 1 decreased free triiodothyronine and one grade 2 pyrexia were possibly related, and all other TRAEs, including 2 treatment-related SAEs (1 grade 4 hyponatremia and 1 grade 2 subarachnoid hemorrhage), were identified as possibly unrelated. Deaths were due to progression disease (n = 3). Preliminary PK analysis showed dose-proportional kinetics. For 12 evaluable pts, 2 pts achieved PR (16.7%), 5 pts was SD. DCR was 58.3%. Median PFS was 16 wks. (range 16-60), PFS of 2 PR pts was 24 and 60 wks. Conclusions: TWP-101 demonstrated a good safety profile without hepatotoxicity frequently observed with other studied CD137 antibodies. Both favorable tolerability and preliminary antitumor activity warrant further evaluation in pts with advanced melanoma and urothelial carcinoma. Clinical trial information: NCT04871334 .

Abstract 2967: Preclinical development of a B7-H3-targeting ADC with a novel DNA topoisomerase I inhibitor for solid tumors

Abstract Introduction: B7-H3 (CD276) is an immunomodulatory protein of the B7 superfamily molecules, it is overexpressed in a wide range of solid tumors. B7-H3 overexpression often correlates with poor survival and higher tumor grade, it has become an attractive target for the development of novel cancer therapies recently. B7-H3 targeting antibody-drug conjugates (ADCs), such as MGC018 and DS7300a, have shown preliminary clinical efficacy. DB-1311 is a B7-H3 targeting ADC comprised of a humanized B7-H3 antibody conjugated to a novel DNA topoisomerase I inhibitor P1021 via a cleavable linker. We herein report preclinical efficacy and safety data of DB-1311 and its differentiation from DS7300a. Methods: The binding of anti-B7-H3 to other B7 family members were evaluated via ELISA and SPR. Anti-B7-H3 antibody was conjugated to P1021 with different Drug-Antibody-Ratio (DAR) values. The efficacy of B7-H3 ADCs with different DAR values was tested in vivo, pharmacokinetics and safety profile were evaluated in cynomolgus monkeys. Based on potency and toxicity analysis, DB-1311, an ADC with DAR6, was selected for preclinical development. In vitro and in vivo studies were then conducted with DB-1311 to further investigate its pharmacological effects. Results: B7-H3 antibody with DAR6 demonstrated higher efficacy than its DAR4 counterpart in lung cancer (Calu6), glioma(U87MG) and prostate cancer (PC-3) models. In monkeys, the DAR6 ADC showed good stability and dose-proportionally increased exposure. Additionally, it was well tolerated with repeat dose administration up to 80 mg/kg and didn’t show significantly worse toxicities than DAR4 counterpart. In preclinical study, DB-1311 demonstrated specific, dose-dependent cytotoxicity toward B7-H3-positive tumor cell lines in vitro and potent antitumor activity in vivo but minimum tumor growth inhibition activity in a B7-H3 negative xenograft model. Moreover, DB-1311 showed more potent antitumor activity than DS7300a analogue in vitro and in vivo. Conclusions: DB-1311, a preclinical B7-H3 ADC candidate, with a DAR value of approximately 6, exhibited potent cytotoxicity in vitro and antitumor activity in vivo toward a range of B7-H3-expressing tumor cell lines representing several cancer types and was well tolerated in cynomolgus monkeys with promising pharmacokinetics characteristics. The preclinical antitumor activity and safety profile warrants further development of DB-1311 to evaluate its efficacy and safety in clinical studies. Citation Format: Chenggang Li, Jun Yao, Chen Qu, Bing Li, Yu Zhang, Rong Shi, Yang Qiu, Haiqing Hua. Preclinical development of a B7-H3-targeting ADC with a novel DNA topoisomerase I inhibitor for solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2967.

Abstract 4928: Gedatolisib, a well-tolerated pan-PI3K/mTOR inhibitor, exhibits potent therapeutic effects on endometrial cancer models regardless of their PI3K pathway mutational status

Abstract Background: The PI3K, AKT, and mTOR (PAM) pathway is one of the most commonly activated oncogenic pathways in gynecological cancers. Loss of PTEN function and PIK3CA activating mutations are especially frequent in endometrial cancer (EC). Targeting the PAM pathway, in combination with other cooperative oncogenic pathways (e.g., the estrogen pathway), is a promising EC treatment strategy. Currently, everolimus, an mTORC1 inhibitor, in combination with letrozole, an aromatase inhibitor, is one of the available hormonal therapy options for patients with advanced endometrioid EC. Most PAM inhibitors (PAM-i) selectively spare (or weakly inhibit) one or more key PAM pathway components, which can lead to drug resistance. To minimize drug resistance, a more comprehensive inhibition of the PI3K isoforms and downstream mTOR complexes may be required. We hypothesized that gedatolisib, which potently inhibits all Class I PI3K isoforms, mTORC1, and mTORC2, can potentially be an effective and well tolerated therapy for patients with EC. Methods: A panel of endometrial, ovarian and cervical cancer cell lines with different PI3K pathway mutational status were assayed for their sensitivity to gedatolisib and other PAM inhibitors (PI3K-α: alpelisib, pan-PI3K: copanlisib; AKT: capivasertib; mTORC1: everolimus; pan-PI3K/mTOR: gedatolisib). Cell viability, cell proliferation, and flow cytometry analytical assays were conducted. Xenograft studies evaluating gedatolisib in EC cell lines were also performed. Results: Gedatolisib strongly inhibited PAM pathway activation, and reduced cell cycle progression and cell viability in the endometrial, ovarian, and cervical cancer cell lines. Compared to the other PAM-i, Gedatolisib exhibited superior anti-proliferative potency and efficacy in almost all the cell lines tested, regardless of the PI3K pathway mutational status or cancer type. In EC xenografts, gedatolisib substantively inhibited tumor growth irrespective of the cell line models’ PI3K pathway mutational status. Conclusions: We demonstrated that, gedatolisib induces superior anti-proliferative activity compared to the other PAM pathway inhibitors, regardless of the PI3K pathway mutational status of the cancer cell lines evaluated. Gedatolisib as a single agent and in combination with other therapies has previously reported promising preliminary clinical efficacy and safety in various solid tumor types, including EC. In summary, nonclinical and preliminary clinical data supports the development of gedatolisib in combination with hormonal therapy for treatment of patients with EC. Citation Format: Stefano Rossetti, Aaron Broege, Ian MacNeil, Ben Rich, Jhomary Molden, Brian Sullivan, Lance Laing. Gedatolisib, a well-tolerated pan-PI3K/mTOR inhibitor, exhibits potent therapeutic effects on endometrial cancer models regardless of their PI3K pathway mutational status. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4928.

The Guard1 clinical trial - A first in-human, phase 1/2 study evaluating AVR-RD-02, a hematopoietic stem cell (HSC) gene therapy for Gaucher disease: Preliminary safety, pharmacodynamic and clinical efficacy results from the subjects observed for up to 24 months post-infusion

The Guard1 clinical trial - A first in-human, phase 1/2 study evaluating AVR-RD-02, a hematopoietic stem cell (HSC) gene therapy for Gaucher disease: Preliminary safety, pharmacodynamic and clinical efficacy results from the subjects observed for up to 24 months post-infusion

A phase 1a dose-escalation, multicenter trial of anti-claudin 18.2 antibody drug conjugate CMG901 in patients with resistant/refractory solid tumors.

352 Background: CMG901, an anti-claudin 18.2 (CLDN18.2) antibody-drug conjugate, has demonstrated potent preclinical anti-cancer activity through monomethyl auristatin E (MMAE)-mediated cytotoxicity with bystander killing, antibody-dependent cellular cytotoxicity, and complement-dependent cytotoxicity. Methods: This Phase 1a trial uses a modified 3+3 dose-escalation design to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary anti-tumor activity in subjects (ages 18-75 years) with advanced gastric, gastroesophageal junction (GEJ), pancreatic cancers, and other solid tumors. Eligible subjects are refractory and/or intolerant to standard therapies. CLDN18.2 expression was not required for study entry, but was retrospectively tested by the central lab. CMG901 was administered intravenously on Day 1 in 3-week (Q3W) cycle at doses of 0.3, 0.6, 1.2, 1.8, 2.2, 2.6, 3.0, and 3.4 mg/kg. Primary endpoints include safety and tolerability. Major efficacy endpoints include objective response rate (ORR) and disease control rate (DCR) based on RECIST v1.1. Pharmacokinetics (PK) and immunogenicity are also assessed. Results: As of August 4, 2022, 27 subjects (13 gastric/GEJ cancer and 14 pancreatic cancer patients) received CMG901 at dose levels up to 3.4 mg/kg. The median prior lines of systemic therapy were 2 (range: 1 to 5). Drug-related grade ≥3 adverse events (AEs) occurred in 3/27 (11.1%) patients. No drug-related grade 4 or 5 AEs were reported. MTD was not reached. In CLDN18.2-positive gastric/GEJ cancer patients, ORR and DCR were 75.0% and 100%, respectively, with ORR of 100% in the 2.6, 3.0, and 3.4 mg/kg Q3W dose cohorts. Median progression-free survival (mPFS) and median overall survival (mOS) were not reached yet. PK data showed that patients had low systemic exposure to unconjugated MMAE. Subsequent results will be presented. Conclusions: CMG901 was well-tolerated with preliminary promising clinical efficacy in patients with CLDN18.2-positive gastric/GEJ cancer. The Phase 1b dose-expansion trial in gastric/GEJ adenocarcinoma, pancreatic cancer, and other solid tumors is rapidly enrolling, with multiple pivotal (Phases 2 and 3) trials planned. Clinical trial information: NCT04805307 . [Table: see text]

Phase I Study of the Anti-Btla Antibody Tifcemalimab As a Single Agent or in Combination with Toripalimab in Relapsed/Refractory Lymphomas

Background: The B- and T-lymphocyte attenuator (BTLA) is an inhibitory receptor expressed on B, T and NK cells. Using Peripheral Blood Mononuclear Cell (PBMC) derived from cancer patients, co-blockade of the BTLA and PD-1 pathways improved antigen specific T cell response compared to either blockade alone. Tifcemalimab (also known as icatolimab, JS004 or TAB004) is a humanized IgG4 monoclonal antibody with a hinge mutation (S228P) that binds BTLA and blocks its interaction with its ligand Herpesvirus Entry Mediator (HVEM). In this first-in-human study, we report the preliminary safety and anti-tumor activity of tifcemalimab as a single agent or in combination with toripalimab (anti-PD-1) in patients with relapsed/refractory (R/R) lymphoma. Methods: Eligible patients with R/R lymphoma were enrolled in this open-label, multicenter study (NCT04477772). Tifcemalimab was administered as a monotherapy at escalating doses of 1, 3 and 10 mg/kg intravenously Q3W, followed by 3 mg/kg and 200 mg monotherapy dose expansion until disease progression or intolerable toxicity. During combination dose escalation, patients received ascending doses of tifcemalimab (100mg and 200mg) plus toripalimab (240mg). Dose-limiting toxicity (DLT) was evaluated by a safety monitoring committee. Study objectives included safety, pharmacokinetics, and efficacy. Results: By the cutoff date of July 21, 2022, a total of 48 patients were enrolled, including 25 in the monotherapy and 23 in the combination subgroup. The lymphoma subtypes included 28 Hodgkin's lymphoma (HL) and 20 non-Hodgkin's lymphoma. The median age was 43.5 (range 19-70) years with 33 (68.8%) male patients. The median prior line of therapy was 4 with 32 (66.7%) progressed upon prior anti-PD-1/L1 therapy. By the cutoff date, the median follow-up was 31.3 weeks. No DLT was observed in either monotherapy or combination dose escalation. Forty-one (83.3%) patients experienced treatment emergent adverse events (TEAEs), 9 (18.8%) of whom experienced grade 3 or above TEAEs. The most common TEAEs were fever (27.1%) and anemia (25.0%). Five treatment-related adverse events led to the discontinuation of the study drug. Ten (40.0%) and 13(56.5%) patients experienced immune related AEs in the monotherapy and combination subgroups, respectively, but all were grade 1 or 2. Among 22 evaluable patients receiving monotherapy, 1 PR (follicular lymphoma) and 7 SD were observed per Lugano criteria. Among all evaluable HL patients receiving the combination regimen (n=12), 1 CR, 4 PR (ORR 41.7%) and 5 SD (DCR 83.3%) were observed. Among them, 11 (91.7%) and 7 (58.3%) patients were refractory to prior anti-PD-1/L1 or anti-CD30 therapy, respectively. The clinical efficacy is durable as all responses are ongoing by the cutoff date, with the duration of response ranges from 2+ to 8+ months. Preliminary data showed a trend of correlation between high HVEM expression and clinical response. Conclusions: Tifcemalimab alone or in combination with toripalimab were well tolerated in all doses evaluated. The combination showed encouraging preliminary clinical efficacy in patients with R/R HL refractory to anti-PD-1/L1 and/or anti-CD30.