T-cell Antitumor Activity Research Articles

First-in-human, phase 1a, dose escalation study of BGB-B167, a CEA x 4-1BB bispecific antibody, as monotherapy or combined with tislelizumab (anti-PD-1), in patients with selected advanced or metastatic solid tumors.

123 Background: BGB-B167 is potentially a first-in-class IgG-based bispecific antibody that targets CEA, a tumor-associated antigen overexpressed in many cancers, and 4-1BB, a key T-cell co-stimulatory receptor expressed on activated CD4+/CD8+ T lymphocytes. Preclinical data suggest BGB-B167 binds to these target proteins with high specificity/affinity, inducing T-cell activation and antitumor activity, with potential for mitigating strong AEs, eg CRS and hepatoxicity. We present results of a first-in-human, phase 1a, open-label, multicenter trial of BGB-B167 given as monotherapy (Part A [A]) or with tislelizumab (TIS) (Part B [B]) (NCT05494762). Methods: Eligibility: ≥18 y with unresectable/metastatic CRC, CEA+ GC or CEA+ NSCLC previously treated with standard systemic therapy or for whom treatment is unavailable; pts with CRC and known MSI-H/dMMR status must have received prior ICI, if available. Primary objectives: safety/tolerability; MTD and RP2D for BGB-B167 ± TIS; key secondary objective: antitumor activity (RECIST v1.1). Results: As of July 7, 2024, 54 pts were enrolled (31 in A, 23 in B) with BGB-B167 dose ranges of 5–1200 mg IV QW assessed in A and 50–600 mg IV QW in B. In A and B, respectively, 29/31 (93.5%) and 18/23 (78.3%) had CRC, 2/31 (6.5%) and 3/23 (13%) had GC, 0/31 (0%) and 2/23 (8.7%) had NSCLC; 19/31 (61.3%) and 18/23 (78.3%) had liver metastases; 20/31 (64.5%) and 14/23 (60.9%) received ≥3 lines of prior therapy. TEAEs occurred in all pts (Table). Most common treatment-related TEAEs were nausea (4/31; 12.9%) and fatigue (3/31; 9.7%) in A and pruritus (5/23; 21.7%) and diarrhea (4/23; 17.4%) in B; there were no treatment-related TEAEs indicative of hepatotoxicity or CRS. There was a single DLT (gr 3 SJS) in a pt who received 600 mg BGB-B167 + TIS (resolved after treatment discontinuation). MTD was not reached. 3 pts (1 with CRC [A]; 1 with CRC and 1 with GC [B]) had confirmed PRs. DoR was ≥5.6 mo for the pt in A and ≥5.6 mo and ≥6.9 mo for the pts in B; all remained on treatment with ongoing responses as of the data cutoff date. DCR (95% CI) was 33.3% (17.3–52.8) in A and 40.9% (20.7–63.6) in B. Serum exposure of BGB-B167 increased dose dependently from 150 to 1200 mg. Conclusions: Overall, BGB-B167 ± TIS was well tolerated and has demonstrated limited antitumor activity in pts with advanced/metastatic CEA+ solid tumors. Clinical trial information: NCT05494762 . Safety. Part ABGB-B167 monotherapy(N=31) Part BBGB-B167 + TIS(N=23) Any TEAE 31 (100.0) 23 (100.0) Any treatment-related TEAE 17 (54.8) 15 (65.2) Gr ≥3 4 (12.9) 1 (4.3) Serious 0 (0) 2 (8.7) Leading to death 0 (0) 0 (0) Leading to treatment discontinuation 0 (0) 1 (4.3) Any imAE 2 (6.5) 5 (21.7) IRRs 4 (12.9) 6 (26.1) Patients with multiple adverse events (AEs) are counted once. All AEs are listed as n (%). imAE, immune-mediated AE; IRR, infusion-related reaction; TEAE, treatment-emergent AE.

Fibroblastic reticular cells generate protective intratumoral T cell environments in lung cancer

Stringent control of Tcell activity in the tumor microenvironment is essential for the generation of protective antitumor immunity. However, the identity, differentiation, and functions of the cells that create critical fibroblastic niches promoting tumor-infiltrating Tcells remain elusive. Here, we show that CCL19-expressing fibroblastic reticular cells (FRCs) generate interconnected Tcell environments (TEs) in human non-small cell lung cancer, including tertiary lymphoid structures and Tcell tracks. Analysis of the FRC-T cell interactome in TEs indicated molecular networks regulating niche-specific differentiation of CCL19-expressing fibroblasts and Tcell activation pathways. Single-cell transcriptomics and cell fate-mapping analyses in mice confirmed that FRCs in TEs originate from mural and adventitial progenitors. Ablation of intratumoral FRC precursors decreased antitumor Tcell activity, resulting in reduced tumor control during coronavirus vector-based immunotherapy. In summary, specialized FRC niches in the tumor microenvironment govern the quality and extent of antitumor Tcell immunity.

Local CpG-Stat3 siRNA treatment improves antitumor effects of immune checkpoint inhibitors

Immune checkpoint blockade (ICB) therapy has significantly benefited patients with several types of solid tumors and some lymphomas. However, many of the treated patients do not have a durable clinical response. It has been demonstrated that rescuing exhausted CD8+ Tcells is required for ICB-mediated antitumor effects. We recently developed an immunostimulatory strategy based on silencing STAT3 while stimulating immune responses by CpG, a ligand for Toll-like receptor 9 (TLR9). The CpG-small interfering RNA (siRNA) conjugates efficiently enter immune cells, silencing STAT3 and activating innate immunity to enhance Tcell-mediated antitumor immune responses. In the present study, we demonstrate that blocking STAT3 through locally delivered CpG-Stat3 siRNA enhances the efficacies of the systemic PD-1 and CTLA4 blockade against mouse A20 B cell lymphoma. In addition, locally delivered CpG-Stat3 siRNA combined with systemic administration of PD-1 antibody significantly augmented both local and systemic antitumor effects against mouse B16 melanoma tumors, with enhanced tumor-associated Tcell activation. Furthermore, locally delivered CpG-Stat3 siRNA enhanced CD8+ Tcell tumor infiltration and antitumor activity in a xenograft tumor model. Overall, our studies in both B cell lymphoma and melanoma mouse models demonstrate the potential of combinatory immunotherapy with CpG-Stat3 siRNA and checkpoint inhibitors as a therapeutic strategy for B cell lymphoma and melanoma.

Real-world treatment patterns and outcomes of patients with advanced melanoma treated with nivolumab plus relatlimab.

The use of programmed death-1 (PD-1) inhibitors has been a pivotal advancement in treating advanced melanoma, yet their efficacy is limited. The approval of relatlimab (RELA), a lymphocyte activation gene 3 protein (LAG-3) antibody, in combination with nivolumab (NIVO), a PD-1 inhibitor, marked a significant stride toward enhancing treatment efficacy for metastatic and unresectable stage 3 and 4 melanoma. This combination has been shown to synergistically improve antitumor activity and effector T-cell activity in the tumor microenvironment, despite limited data on real-world outcomes. Our retrospective review at a tertiary cancer center of patients with stage 3 and 4 melanoma treated with NIVO-RELA revealed an overall response rate (ORR) of 39%, with notable improvements in median PFS and ORR, especially in first-line treated patients. Our study highlights the superior efficacy of NIVO-RELA over previous reports, demonstrating its significant potential in the treatment landscape of advanced melanoma.

A novel bispecific peptide targeting PD-1 and PD-L1 with combined antitumor activity of T-cells derived from the patients with TSCC

Programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) are key immune checkpoints (ICs) that critically influence immunotherapy. Tumor resistance to single IC-targeting drugs has increased interest in dual-target drugs, which have shown feasibility for cancer treatment. In this study, we aimed to develop dual-target peptide drugs targeting the PD-1/PD-L1 pathway and to evaluate their efficacy compared to functional antibodies in enhancing the cytotoxicity of human T cells against tongue squamous carcinoma cell lines. Through sequence analysis and peptide truncation, we modified a pre-existing peptide named nABPD-1 targeting PD-1. Subsequently, we obtained two novel peptides named nABPD-2 and nABPD-3, with nABPD-2 showing an enhanced affinity for human PD-1 protein compared to nABPD-1. Importantly, nABPD-2 exhibited dual-targeting capability, possessing a high affinity for both PD-L1 and PD-1. Furthermore, nABPD-2 effectively promoted the cytotoxicity of human T cells against tongue squamous carcinoma cell lines, surpassing the efficacy of anti-PD-1 or anti-PD-L1 functional antibodies alone. Considering that nABPD-2 has lower production costs and dose requirements, it can potentially be used in therapeutic applications.

Copy Number Profiling Implicates Thin High-Grade Squamous Intraepithelial Lesions as a True Precursor of Cervical Human Papillomavirus-Induced Squamous Cell Cancer

Full-thickness high-grade squamous intraepithelial lesions (HSIL) are precursors of invasive cervical squamous cell carcinoma (SCC). The World Health Organization and Lower Anogenital Squamous Terminology Standardization Project for human papilloma virus (HPV)–associated lesions divide full-thickness HSIL of the cervix into thin HSIL with thickness of 1 to 9 cell layers and the typical full-thickness HSIL of >10 cell layers. Although HPV oncogene transcripts and p16ink4a overexpression, as markers of transforming HPV infection, are detectable in thin HSIL, the biological significance of thin HSIL in cervical carcinogenesis remains poorly understood. To further characterize thin HSIL, we performed a comparative study of chromosomal copy number variations (CNV), an analysis of dysregulated genes present in the segments with CNV, and a generalized genetic complexity calculation for 31 thin HSIL, 31 thick HSIL, 24 microinvasive SCC (pT1a SCC), and 22 highly invasive SCC samples. Thin HSIL share various CNV and specific dysregulated gene pathways with thick HSIL and invasive SCC. Thin HSIL exhibited an average CNV of 11.6% compared with 14.1% for thick HSIL, 15.5% for pT1a SCC, and 26.6% for highly invasive SCC. The CNV included gains at 1q and 3q (40% and 43%, respectively), partial loss of 3p, and loss of chromosomes 11 (18%), 16 (50%), 20 (35%), and 22 (40%). Pathways affected solely in thin HSIL were those enhancing immune evasion and primarily involved the (interleukin) IL6, IL21, and IL23 genes. ILs are transiently upregulated in response to infection and play a crucial role in mounting antitumor T-cell activity. Deregulation reflects an attempt by the HPV to evade the initial immune response of the host. The primary pathways shared by thick HSIL and invasive SCC were interactions between lymphoid and nonlymphoid cells, NOTCH2 signaling, tight junction interactions (primarily of the claudin family), and FGR2 alternative splicing. Our results show that thin HSIL carry similar genetic changes as thick HSIL and SCC, indicating that thin HSIL are true precursor lesions that can progress to thick HSIL and SCC.

IMMU-05. TARGETING THE DYSREGULATED DNA METHYLOME DURING CAR T CELL MANUFACTURING IMPROVES THEIR FITNESS IN IMMUNOCOMPETENT BRAIN TUMOR MODELS

Abstract BACKGROUND Epigenetic reprogramming and T-cell exhaustion are key factors impacting the effectiveness of chimeric antigen receptor (CAR) T-cell immunotherapies in brain tumors. These processes are regulated by DNA methylation, an epigenetic modification that is crucial for gene regulation. Here, we investigated whether targeting the dysregulated DNA methylome in engineered immune cells can improve their anti-tumor efficacy. METHODS We optimized a transduction protocol that incorporates adding DNA methyltransferase inhibitors (DNMTi) early during the manufacturing process of murine CAR T-cells targeting B7-H3. We then used standard in vitro assays and immunocompetent glioma models to evaluate whether DNMTi treatment improved CAR T-cell effector functions by regulating activation, memory differentiation, and cytokine responses in adoptive T-cells. RESULTS In repeated-stimulation assays, CAR T-cells generated in the presence of DNMTi exhibited significantly higher levels of expansion and persistence compared to CAR T-cells without DNMTi exposure. Notably, CAR T-cells manufactured in the presence of DNMTi persisted up to 12 repeat stimulations, in contrast to a maximum of 7 stimulations for CAR T-cells generated without DNMTi treatment. Moreover, DNMTi-treated CAR T-cells expanded up to 55-fold higher than T-cells generated without DNMTi treatment upon repeated-stimulation with B7-H3-positive glioma cells. This was also associated with remarkably enhanced secretion of immune-stimulatory cytokines that persisted across repetitive stimulations. Furthermore, DNMTi-treated CAR T-cells exhibited greater cytotoxicity at lower effector-to-target ratios compared to untreated CAR T-cells, with sustained differential cytotoxicity even after the 4th stimulation. Preliminary in vivo data from immunocompetent glioma models further support the potential of DNMTi pre-treatment, showing improved T-cell persistence and reduced dose requirements. Mechanistic studies suggest that DNMT inhibition enhances B7-H3 CAR T-cell anti-tumor activity by regulating memory differentiation of CAR T-cells early in the production phase. CONCLUSION This study proposes that DNMTi pre-treatment may offer a promising approach for optimizing CAR T-cell manufacturing and enhancing performance in brain tumors.

IMMU-06. CAR DESIGN SHAPES THE BRAIN TUMOR IMMUNE MICROENVIRONMENT: IMPACT ON ACTIVITY AND PERSISTENCE OF ANTI-GLIOMA ADOPTIVE T CELL IMMUNOTHERAPY

Abstract BACKGROUND B7-H3 CAR T-cells effectively eradicate brain tumors in xenograft models and have proven safe in clinical trials, yet no objective responses were observed in patients. The limited efficacy is partly attributed to the immunosuppressive tumor microenvironment (TME), a characteristic not fully recapitulated in investigations using xenograft models. In this study, we set to optimize B7-H3 CAR structure and examine the effects of CAR design on the brain TME using an immunocompetent glioma model. METHODS We generated a panel of fully murine B7-H3 CARs with variations in transmembrane, co-stimulatory, and activation domains. This enabled us to comprehensively investigate their effector functions within the intact immune system. High-dimensional flow cytometry and single-cell RNA sequencing were then used to investigate changes in the brain TME following CAR T-cell therapy. RESULTS While five out of six B7-H3 CARs with single co-stimulatory domains exhibited potent functionality in vitro, optimizing co-stimulation and signaling failed to enhance their anti-glioma efficacy in vivo. To further enhance therapeutic effectiveness and persistence, we incorporated 4-1BB and CD28 co-stimulation through transgenic expression of 4-1BBL on CD28-based CAR T-cells. Although this design significantly improved anti-glioma efficacy in vitro, it conferred no additional benefits in vivo. Analysis of the TME revealed that CAR T-cell therapy influenced the immune composition of the brain TME. Successful anti-tumor responses were dictated by the recruitment, activation, and spatial localization of unique inflammatory ‘immune hubs’ containing specific subsets of macrophages and endogenous T-cells. Interestingly, depletion of brain macrophages using CSF1R inhibitor markedly inhibited CAR T-cell anti-tumor activity. CONCLUSION Our study highlights the critical role of CAR structural design and its modulation of the TME in mediating the efficacy of CAR T-cell therapy in brain tumors. Yet, more specific targeting and/or reprogramming of the TME is warranted for the successful design of effective adoptive immunotherapies for high-grade glioma.

Overexpression of an Engineered SERPINB9 Enhances Allogeneic T-cell Persistence and Efficacy.

Allogeneic chimeric antigen receptor (CAR)-expressing T cells offer many advantages over autologous therapies, but their benefits are curtailed by graft-versus-host disease and elimination by recipient immune cells. Moreover, just as with autologous therapies, allogeneic CAR T cells are susceptible to activation-induced cell death (AICD) caused by chronic antigen exposure (CAE). Granzyme B- and Fas/Fas ligand-initiated caspase-mediated apoptoses are key mechanisms of T-cell death caused by T/NK cell-mediated allorejection or CAE. We explored a protective strategy of engineering CAR T cells to overexpress variants of the Granzyme B-specific serine protease inhibitor SERPINB9 (SB9) to improve allogeneic T-cell persistence and antitumor efficacy. We showed that the overexpression of an SB9 variant with broadened caspase specificity, SB9(CAS), not only significantly reduced rejection of allogeneic CAR T cells but also increased their resistance to AICD and enabled them to thrive better under CAE, thus improving allogeneic T-cell persistence and antitumor activity in vitro and in vivo. In addition, although SB9(CAS) overexpression improved the efficacy of allogeneic CAR T-cell therapy by conferring protection to cell death, we did not observe any autonomous growth, and the engineered CAR T cells were still susceptible to an inducible suicide switch. Hence, SB9(CAS) overexpression is a promising strategy that can strengthen current development of cell therapies, broadening their applications to address unmet medical needs.

Phase 1/2 trial of the HPK1 inhibitor NDI-101150 as monotherapy and in combination with pembrolizumab: Clinical update.

3083 Background: NDI-101150 is a potent, selective, oral inhibitor of hematopoietic progenitor kinase 1 (HPK1), with a different immunotherapy mechanism to other checkpoint inhibitors. NDI-101150 reactivates anti-tumor activity of T-cells, B-cells and dendritic cells (DCs), even under immunosuppressive conditions. Methods: Safety and preliminary efficacy (primary endpoints) of NDI-101150 alone (50–200 mg once-daily in 28-day cycles) and in combination with pembrolizumab are being assessed in patients (pts) with relapsed or metastatic solid tumors. NDI-101150 monotherapy expansion cohorts in renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC) and gastric/gastroesophageal (G/GEJ) cancer are also being assessed. Results: Dose escalation/expansion data as of Dec 13, 2023 are presented. Treatment (tx)-related adverse effects (TRAEs) in the safety set (N=39) for NDI-101150 monotherapy are presented in the table. 30 (76.9%) pts reported ≥1 TRAE and 5 (12.8%) pts reported grade ≥3 TRAEs. Most common TRAEs were nausea, vomiting, diarrhea and fatigue. Combination tx TRAEs (N=7) recapitulate the monotherapy profile (data not shown). NDI-101150 induced clinical benefit in 4/24 (16.7%) response-evaluable pts: complete response in 1 pt with clear cell RCC; stable disease (SD) ≥6 months in 3 pts (RCC [21 months], pancreatic cancer and endometrial cancer). Unconfirmed SD was noted in 2 pts with RCC, and in 1 pt each with NSCLC and G/GEJ cancer. Nearly dose-proportional increases in exposure were observed on Day 1 of Cycle 1 (C1) across 50–200 mg, with steady state achieved between Days 15 and 28 of tx. Pharmacokinetic profiles of monotherapy and combination tx cohorts were similar. Sustained inhibition of pSLP76 of >50% relative to pre-tx levels (predicted to achieve efficacy in nonclinical models) was observed at all doses tested by Day 15 of C1. Using a custom 12-plex immunofluorescence assay to monitor changes in the tumor immune microenvironment, an on-tx biopsy assessment from a pt with RCC showed increased infiltration of activated CD8+ T-cells and DCs compared to archival biopsy, aligning with the proposed mechanism of action. Conclusions: The observed clinical benefit and safety profile support continued evaluation of NDI-101150 as a viable next-generation immunotherapeutic. Clinical trial information: NCT05128487 . [Table: see text]

A phase 2 study of EIK1001, a Toll-like receptor 7/8 (TLR7/8) agonist, in combination with pembrolizumab and chemotherapy in patients with stage 4 non-small cell lung cancer.

TPS8667 Background: Immune checkpoint inhibitors (ICIs) relieve immunosuppression of tumor-reactive T cells and enhance antitumor immune response. Significant advances for the treatment of non-small cell lung cancer (NSCLC) have been made using the ICI pembrolizumab in combination with chemotherapy, which confers significant clinical benefit relative to chemotherapy and placebo. Not all patients benefit, however, and some become refractory. As a result, there remains a critical unmet need to develop therapies for the treatment of NSCLC. EIK1001 is a TLR7/8 agonist that stimulates myeloid and plasmacytoid dendritic cells, activating immune and inflammatory responses. This dual activity provides another pathway, distinct from effects on checkpoint proteins, to enhance antitumor T-cell activity alone or in combination with ICIs. Methods: Study EIK1001-005 is a multicenter, Phase 2, open-label study of EIK1001 in combination with pembrolizumab and chemotherapy – carboplatin plus either pemetrexed or paclitaxel – in participants (pts) with histologically confirmed Stage 4 nonsquamous or squamous NSCLC, respectively. This study includes a safety run-in period for pts enrolled in each NSCLC cohort. If < 2 dose-limiting toxicities occur, an expansion phase for each NSCLC cohort will be conducted at the target dose to evaluate the tolerability and efficacy of EIK1001 (QW) in combination with pembrolizumab and chemotherapy (administered Q3W per label). Key eligibility criteria include pts ≥ 18 years of age with a life expectancy of at least 3 months, histologically or cytologically confirmed Stage 4 NSCLC (nonsquamous or squamous) without prior therapy for advanced NSCLC, confirmation that mutation-directed therapy is not indicated as first-line, and at least 1 measurable lesion at Baseline according to RECIST 1.1. The primary objective of this study is to determine the safety and tolerability of EIK1001 in combination with pembrolizumab and chemotherapy. The secondary objectives are evaluation of antitumor activity by objective response rate (ORR; defined as the proportion of pts who have a confirmed complete response [CR] or partial response [PR] per RECIST 1.1) and duration of response (DOR) by RECIST 1.1. Other exploratory objectives include evaluation of anti-tumor activity (ORR/DOR) by immune-related RECIST 1.1, overall survival, progression-free survival, investigation of the relationship between treatment with EIK1001 in combination with pembrolizumab/chemotherapy and biomarkers predictive of response, and the pharmacokinetic parameters of EIK1001. This study opened on 29 Jan 2024. Clinical trial information: NCT06246110 .

Safety and preliminary efficacy of EIK1001 in combination with atezolizumab in participants with advanced solid tumors.

2618 Background: Immune checkpoint inhibitors (ICIs) relieve immunosuppression of tumor-reactive T cells and enhance antitumor immune response; however, not all patients benefit and some become refractory. EIK1001 is a Toll-like receptor (TLR)7/8 agonist that stimulates myeloid and plasmacytoid dendritic cells, activating immune and inflammatory responses. This dual activity provides another pathway, distinct from effects on checkpoint proteins, to enhance antitumor T-cell activity alone or in combination with ICIs. Methods: Study BDB001-102 was a Phase 1, open-label, dose-escalation/expansion study of EIK1001 combined with atezolizumab (comb Rx). Enrollment criteria included participants (pts) ≥ age 18 with confirmed, RECIST-measurable advanced solid tumors. Primary study objectives included safety and tolerability, and secondary objectives included evaluation of dose-limiting toxicities, pharmacokinetics (PK), pharmacodynamics, and preliminary efficacy by RECIST 1.1. During dose escalation, pts received a range of doses of EIK1001 (QW IV) in combination with atezolizumab (1200 mg Q3W). Results: Forty-one pts (median age 65 years [range = 32 to 79]) with multiple, distinct histological tumor types and a median of 3 prior Rx regimens were enrolled. Overall, a total of 28/41 (68.3%) receiving EIK1001 + atezolizumab experienced a treatment-related adverse event (TRAE). Of these, 4/41 (9.8%) experienced a ≥ Grade 3 TRAE, including fatigue, nausea, hyponatremia, and lymphedema. Only 1/41 (2.4%) experienced manageable cytokine release syndrome. There were no deaths due to TRAEs. Of the efficacy-evaluable pts (n = 37), complete response (CR) or partial response (PR) was observed for 3/37 (8.1%). Disease control (including CR, PR, or stable disease) was observed in 19/37 (51.4%). The median duration of response (DOR) was 13 months (range = 10 to 27). One responder was PD-L1 negative yet had a > 12-month DOR; another had a history of prior anti-PD-1 Rx yet experienced a 10-month DOR on comb Rx. EIK1001 PK was linear and dose-proportional, and was not affected by combination with atezolizumab. Conclusions: Overall, EIK1001 was well-tolerated with a manageable safety profile and showed encouraging preliminary efficacy across several tumor types in combination with atezolizumab. Responses were observed even in pts not anticipated to respond to atezolizumab monotherapy. Further development of EIK1001 is underway. Clinical trial information: NCT04196530 .

Safety and preliminary efficacy of EIK1001 in combination with pembrolizumab in participants with advanced solid tumors.

2521 Background: Immune checkpoint inhibitors (ICIs) relieve immunosuppression of tumor-reactive T cells and enhance antitumor immune response; however, not all patients benefit and some become refractory. EIK1001 is a Toll-like receptor (TLR)7/8 agonist that stimulates myeloid and plasmacytoid dendritic cells, activating immune and inflammatory responses. This dual activity provides another pathway, distinct from effects on checkpoint proteins, to enhance antitumor T-cell activity alone or in combination with ICIs. Methods: Study BDB001-101 was a Phase 1, open-label, dose-escalation/expansion study of EIK1001 as either monotherapy (mono Rx; previously reported) or combined with pembrolizumab (comb Rx). Enrollment criteria included participants (pts) ≥ age 18 with confirmed, RECIST-measurable advanced solid tumors. Primary study objectives included safety and tolerability, and secondary objectives included evaluation of dose-limiting toxicities, pharmacokinetics (PK), pharmacodynamics, and preliminary efficacy by RECIST 1.1. During comb Rx dose escalation, pts received a range of doses of EIK1001 (QW IV) in combination with pembrolizumab (200 mg Q3W). Results: Fifty-one pts (median age 67 [range 33 to 86]) with multiple, distinct histological tumor types and with a median of 3 prior Rx regimens were enrolled. Overall, a total of 42/51 (82.4%) comb Rx pts experienced a treatment-related adverse event (TRAE). A total of 9/51 (17.7%) experienced a ≥ Grade 3 TRAE, including fatigue, cytokine release syndrome (CRS), hemiparesis, hypertension, joint range of motion reduced, muscular weakness, pancreatitis, rash (maculopapular), skin plaque, and stomatitis. Overall, 5/51 (9.8%) experienced manageable CRS, with only 1 discontinuation due to CRS. There were no deaths due to TRAEs. Of the efficacy-evaluable pts (n = 50), complete response (CR) or partial response (PR) was observed for 7/50 (14.0%), including 3 CR and 4 PR. Disease control (including CR, PR, or stable disease) was observed in 24/50 (48.0%). The median duration of response was 10 months (range = 4 to 32 months). Responses were observed in pts with prior anti-PD-1 exposure as well as in those with low or negative PD-L1 tumor expression. EIK1001 PK was linear and dose-proportional, and combination with pembrolizumab did not affect EIK1001 PK. Conclusions: Overall, EIK1001 was well-tolerated with a manageable safety profile and showed encouraging preliminary efficacy across several tumor types in combination with pembrolizumab. Responses were observed even in heavily pretreated patients not anticipated to respond to pembrolizumab monotherapy. Further development of EIK1001 is underway. Clinical trial information: NCT03486301 .

HPN328, a Trispecific T Cell-Activating Protein Construct Targeting DLL3-Expressing Solid Tumors.

Delta-like ligand 3 (DLL3) is expressed in more than 70% of small cell lung cancers (SCLCs) and other neuroendocrine-derived tumor types. SCLC is highly aggressive, and limited therapeutic options lead to poor prognosis for patients. HPN328 is a trispecific T cell-activating construct (TriTAC) consisting of three binding domains: a CD3 binder for T-cell engagement, an albumin binder for half-life extension, and a DLL3 binder for tumor cell engagement. In vitro assays, rodent models, and non-human primates were used to assess the activity of HPN328. HPN328 induces potent dose-dependent killing of DLL3-expressing SCLC cell lines in vitro, concomitant with T-cell activation and cytokine release. In an NCI-H82 xenograft model with established tumors, HPN328 treatment led to T-cell recruitment and anti-tumor activity. In an immunocompetent mouse model expressing a human CD3ε epitope, mice previously treated with HPN328 withstood tumor rechallenge, demonstrating long-term anti-tumor immunity. When repeat doses were administered to cynomolgus monkeys, HPN328 was well tolerated up to 10 mg/kg. Pharmacodynamic changes, such as transient cytokine elevation, were observed, consistent with the expected mechanism of action of T-cell engagers. HPN328 exhibited linear pharmacokinetics in the given dose range with a serum half-life of 78 to 187 hours, supporting weekly or less frequent administration of HPN328 in humans. Preclinical and nonclinical characterization suggests that HPN328 is a highly efficacious, safe, and novel therapeutic candidate. A phase 1/2 clinical trial is currently underway testing safety and efficacy in patients with DLL3-expressing malignancies.

Sharks give a handle to potent anti-tumor multiparatopic antibodies inducing membrane depletion of PD-L1

Despite the immense clinical success of the antibody therapeutics that neutralize programmed death receptor ligand 1 (PD-L1) and thus resurrect Tcell antitumor activity, the patient response rates remain low. In this issue of Cell Chemical Biology, Ludwig etal.1 reveal novel topologies of multiparatopic antibodies that mediate potent PD-L1 downregulation.

Abstract CT141: mRNA-4157 (V940) individualized neoantigen therapy (INT) + pembrolizumab (pembro) in advanced unresectable HPV- head & neck carcinoma (HNSCC): Clinical & translational analysis

Abstract Introduction: In HPV- HNSCC, limited durable clinical responses to PD1/PD-L1 blockade may be due to diminished effector cytolytic activity and clonal diversity.1-4 mRNA-4157 is a novel mRNA-based INT that encodes up to 34 neoantigens inducing specific antitumor T-cell activation; durable clinical responses with pembro have been shown in melanoma.5 We assessed INT + pembro in unresectable, metastatic HPV- HNSCC in the Phase 1 mRNA-4157-P101/KEYNOTE-603 study (NCT03313778). Methods: Part C of this study enrolled ≥18-year-old patients (pts) with CPI-naïve, recurrent/metastatic HPV- HNSCC. Eligible pts received 200 mg pembro Q3W IV during a 6-week lead-in, then combined with 1 mg INT ≤9 doses Q3W IM, and until disease progression, unacceptable toxicity, or ≤35 total cycles of pembro. Objectives included safety, tolerability and preliminary clinical activity. Peripheral blood was collected longitudinally for both immunogenicity via IFN-γ ELISpot and ctDNA analyses. Next generation sequencing was performed on baseline tumor biopsies. Results: A total of 28 enrolled pts received pembro; 22 received INT + pembro. Most adverse events (AEs) related to INT were grade 1-2; most common were influenza-like illness, injection site pain, and pyrexia. No grade 4/5 AEs were related to INT. Three pts had grade 3 events (pyrexia, increased lipase, and decreased lymphocyte count) attributed to both INT and pembro. Six pts discontinued prior to INT (death/disease progression/deterioration). Response rate for INT + pembro was 27.3% (6/22; 95% CI, 10.7-50.2); disease control rate was 63.6% (14/22; 95% CI, 40.7-82.8) per RECIST V1.1 with best overall response of 2 (9.1%) complete, 4 (18.2%) partial response, and 8 (36.4%) stable disease at data cut-off (May 2023); with median follow-up of 38.4 weeks (range, 7.7-198.3). Median (95% CI) PFS and OS were 15.0 weeks (11.6-38.6) and 107.1 weeks (42.7-NE), respectively. Sustained de novo T-cell induction to targeted neoantigens was observed in 5/5 pts with available samples. A decrease in ctDNA levels post-baseline was observed in 3/4 responders (8 available samples). Differential gene expression from pretreatment tumor samples suggests increased inflamed T-cell-associated gene expression (Benjamini-Hochberg-adjusted descriptive p<0.05, for hallmark inflammatory response) in INT + pembro responders. Conclusions: INT + pembro had a manageable safety profile, showed evidence for activation of immune responses, and induced preliminary clinical responses in pts with HPV- HNSCC. Further testing of INT + pembro in a randomized setting may be warranted.

Abstract CT292: Phase II study of pembrolizumab in combination with lenvatinib in patients with triple negative breast cancer (TNBC), non-small cell lung cancer (NSCLC), and other tumor types and brain metastases

Abstract Background: Many patients develop brain metastasis during the course of their disease and it represents the cause of death in more than half of them. The prognosis and survival of patients with brain metastases remains poor with limited palliative treatment options. Thus, there is a need to develop new strategies for the therapeutic management of patients with brain metastases. Inflammatory stimuli originating from CNS tumors may increase the permeability of the blood-brain barrier and promote immune cell activation and infiltration into tumors. Several studies have demonstrated now the efficacy of immune checkpoint inhibitors in patients with melanoma with active brain metastases. The modulation of VEGF-mediated immune suppression via angiogenesis inhibition may augment the activity of immune checkpoint inhibitors. Lenvatinib is an oral, potent multiple receptor tyrosine kinase inhibitor that selectively inhibits VEGFRs, VEGFR1 (FLT1), VEGFR2 (KDR), and VEGFR3 (FLT4), in addition to other pro-angiogenic and oncogenic pathway-related receptor tyrosine kinases. The combination of lenvatinib and pembrolizumab is approved for patients with metastatic endometrial carcinoma and renal cancer, and it is investigated in other tumor types with promising preliminary results. We hypothesize that pembrolizumab and lenvatinib will be an effective treatment for TNBC, NSCLC, and other solid tumor types with brain metastases by decreasing angiogenic tumor activity and improving antitumor T-cell activity. Methods: This is a single-center, open-label, multi-cohort Phase II study evaluating the efficacy and safety of pembrolizumab in combination with lenvatinib in patients with solid tumors and brain metastases. The study has 3 cohorts: triple negative breast cancer (TNBC), non-small cell lung cancer (NSCLC), and other solid tumor types with established or preliminary clinical evidence of efficacy of programmed cell death-1 (PD-1) and angiogenesis inhibitors. Eligible patients will have at least 1 unirraditated or progressing brain metastasis of 0.5-2 cm on brain MRI. The study is conducted using a Simon’s optimal two-stage design, and approximately 87 patients will be enrolled concurrently (n=29 per cohort). Pembrolizumab (200 mg intravenously on Day 1 of each cycle) and lenvatinib (20 mg orally once daily) are administered in 21-day cycles for a maximum of 24 months. The primary endpoint is intracranial objective response rate at 4 months as assessed by the modified Response Evaluation Criteria in Solid Tumors (mRECIST). Exploratory analyses will include evaluation of tissue and blood-based immune-related correlates of response to the pembrolizumab and lenvatinib combination. The first patient was enrolled in January 2022 and accrual of patients is ongoing (NCT05064280). Citation Format: Ecaterina E. Dumbrava, Emma J. Montazari, Uyen M. Vu, Tiantian Cai, Mehmet Altan, Nuhad K. Ibrahim, Debra N. Yeboa, Jing Li, Frederick F. Lang, Gisela Sanchez, Isabella C. Glitza, Barbara J. O'Brien, Rashmi K. Murthy, Jianbo Wang, Tanisha T. Darko, Denisse Velazquez, Komal Shah, Funda Meric-Bernstam, Hussein Tawbi, Jordi Rodon. Phase II study of pembrolizumab in combination with lenvatinib in patients with triple negative breast cancer (TNBC), non-small cell lung cancer (NSCLC), and other tumor types and brain metastases [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 CT292.

Occurrence and Management of Immunotherapy-Associated Adverse Events in Patients with Gynecological Cancers.

Immune checkpoint inhibitors (ICIs) have emerged as an essential therapeutic approach in treating many solid tumors. ICIs enhance the body's anti-tumor T-cell activity, resulting in a novel spectrum of immunotherapy-related side effects. This novel spectrum of adverse events differs significantly from the side effects of conventional chemotherapy. It, therefore, requires special attention in the diagnosis and management of immunotherapy-related adverse events (irAEs). The present study aimed to retrospectively analyze the incidence, diagnosis, and management of irAEs in patients with gynecologic malignancies who received ICIs and to discuss these findings in the context of the recent literature. In the present retrospective overview, we evaluated patients with gynecologic malignancies (breast, endometrial, cervical, ovarian) who received ICIs with regard to the incidence, type, and time to onset of irAEs. A total of 61 patients treated at the Department of Gynecology and Obstetrics, University Medical Center Mainz, Germany, between 2018 and 2023 were included in the analysis. A total of 32.8% of patients developed an irAE of any grade or type. The median time to irAE was 24 weeks. The most frequently observed irAEs were grade 1 (20%) or 2 (35%). Immunotherapy-related grade 3 or 4 adverse events occurred in 45% of patients (40% grade 3, 5% grade 4). The most common type of irAE in our cohort was hypothyroidism, followed by hepatitis and colitis. Cox regression analysis identified the duration of ICI therapy as the only significant factor influencing the incidence of irAEs (p = 0.004). The broad spectrum of irAEs and the onset time of irAEs are important challenges of therapy with ICIs, requiring proactive monitoring and tailored management strategies to optimize the safety and efficacy of immunotherapy.

IL7 in combination with radiotherapy stimulates a memory T-cell response to improve outcomes in HNSCC models

Clinically approved head and neck squamous cell carcinoma (HNSCC) immunotherapies manipulate the immune checkpoint blockade (ICB) axis but have had limited success outside of recurrent/metastatic disease. Interleukin-7 (IL7) has been shown to be essential for effector T-cell survival, activation, and proliferation. Here, we show that IL7 in combination with radiotherapy (RT) is effective in activating CD8 + T-cells for reducing tumor growth. Our studies were conducted using both human papillomavirus related and unrelated orthotopic HNSCC murine models. Immune populations from the tumor, draining lymph nodes, and blood were compared between treatment groups and controls using flow cytometry, proteomics, immunofluorescence staining, and RNA sequencing. Treatment with RT and IL7 (RT + IL7) resulted in significant tumor growth reduction, high CD8 T-cell tumor infiltration, and increased proliferation of T-cell progenitors in the bone marrow. IL7 also expanded a memory-like subpopulation of CD8 T-cells. These results indicate that IL7 in combination with RT can serve as an effective immunotherapy strategy outside of the conventional ICB axis to drive the antitumor activity of CD8 T-cells.

Abstract 1351: Preclinical characterization of BMS-986288, a novel non-fucosylated (NF) anti-cytotoxic T lymphocyte antigen-4 (anti-CTLA-4) Probody® therapeutic

Abstract Introduction: Blockade of the CTLA-4 pathway with ipilimumab (IPI), alone and in combination with nivolumab (anti-programmed death-1 antibody), has shown clinical benefit in multiple tumor types. However, not all tumors respond to IPI ± nivolumab, and peripheral effects can lead to immune-related adverse events. To enhance the therapeutic index of CTLA-4-directed therapy, a proprietary Probody® therapeutics technology platform was used to develop a modified version of IPI. BMS-986288 is an anti-CTLA-4 antibody that combines a Probody® therapeutic masking peptide and protease-cleavable linker, designed to localize anti-CTLA-4 activity to the tumor microenvironment, with an NF Fc region hypothesized to enhance antigen-presenting cell (APC)-mediated T-cell priming and regulatory T cell (Treg) modulation via increased binding to the FcγRIIIA (CD16) receptor. Here, we present the characterization of the mechanism of action and pharmacodynamic (PD) response of BMS-986288 in preclinical models. Methods: APC-mediated T-cell priming and antigen-specific responses were evaluated in a superantigen model using peripheral blood mononuclear cells (PBMCs) and human CTLA-4 knock-in (KI) mice. Antitumor activity and immune cell population changes were assessed in an MC38 tumor model implanted in human CTLA-4 KI mice. Intratumoral Treg depletion was further investigated using patient-derived dissociated tumor samples as a physiologically relevant model. Peripheral PD effects and tolerability of BMS-986288 were evaluated in a non-human primate (NHP) Ad5 vaccine model. Results: Protease-cleaved BMS-986288 demonstrated enhanced APC-mediated T-cell priming compared with IPI in superantigen-stimulated PBMCs. Similarly, administration of superantigen staphylococcal enterotoxin B (SEB) peptide elicited an increased antigen-specific T-cell receptor (Vβ8+) T-cell response after treatment with cleaved BMS-986288 vs IPI in human CTLA-4 KI mice. In the MC38 tumor-bearing mouse model, BMS-986288 showed enhanced antitumor activity as compared to IPI, with tumor clearance in all mice. Although BMS-986288 enhanced intratumoral CTLA-4+ Treg depletion in the MC38 model, limited Treg depletion was observed in the patient-derived dissociated tumor model with an NF anti-CTLA-4 antibody without the masking peptide, potentially reflecting differences in CTLA-4 expression on human vs mouse Tregs. BMS-986288 reduced PD effects in the peripheral blood compartment and increased tolerability in NHP relative to IPI. Conclusion: BMS-986288 leverages unique characteristics to differentiate it from IPI, enhancing APC-mediated T-cell priming and anti-tumor activity while also reducing peripheral activity in preclinical models. These data support an ongoing phase 1/2 clinical trial of BMS-986288 (NCT03994601) in patients with advanced solid tumors. Citation Format: Amy Jhatakia, Mohammed Nasser, Anandaroop Mukhopadhyay, Kyeongah Kang, Courtni Newsome, Neha Gupta, Remie Gail Z. Mandawe, Felix Findeisen, Jack A. Lohre, Leslie Leung, Yun Wei, Joshua Dobroff, Karen Price, John Engelhardt, Mark Selby, Alan J. Korman, Nicholas Wilson. Preclinical characterization of BMS-986288, a novel non-fucosylated (NF) anti-cytotoxic T lymphocyte antigen-4 (anti-CTLA-4) Probody® therapeutic [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1351.