anti-PD1 Antibody Research Articles

First-line penpulimab (an anti-PD1 antibody) and anlotinib (an angiogenesis inhibitor) with nab-paclitaxel/gemcitabine (PAAG) in metastatic pancreatic cancer: a prospective, multicentre, biomolecular exploratory, phase II trial

Metastatic pancreatic cancer (mPC) has a dismal prognosis. Herein, we conducted a prospective, multicentre, single-arm, phase II trial evaluating the efficacy and safety of penpulimab and anlotinib in combination with nab-paclitaxel/gemcitabine (PAAG) in patients with first-line mPC (NCT05493995). The primary endpoints included the objective response rate (ORR) and disease control rate (DCR), while secondary endpoints encompassed progression-free survival (PFS), overall survival (OS), and safety. In 66 patients analysed for efficacy, the best response, indicated by the ORR, was recorded at 50.0% (33/66) (95% CI, 37.4–62.6%), with 33 patients achieving partial response (PR). Notably, the DCR was 95.5% (63/66, 95% CI, 87.3–99.1%). The median PFS (mPFS) and OS (mOS) were 8.8 (95% CI, 8.1–11.6), and 13.7 (95% CI, 12.4 to not reached) months, respectively. Grade 3/4 treatment-related adverse events (TRAEs) were reported in 39.4% of patients (26/66). In prespecified exploratory analysis, patients with altered SWI/SNF complex had a poorer PFS. Additionally, low serum CA724 level, high T-cell recruitment, low Th17 cell recruitment, and high NK CD56dim cell scores at baseline were potential predicative biomarkers for more favourable efficacy. In conclusion, PAAG as a first-line therapy demonstrated tolerability with promising clinical efficacy for mPC. The biomolecular findings identified in this study possess the potential to guide the precise clinical application of the triple-combo regimen.

The efficacy and safety of donafenib combined with transcatheter arterial chemoembolization and anti-PD-1 antibodies as first-line therapy for hepatocellular carcinoma: A retrospective study.

e16178 Background: In Phase III study (ZGDH3), donafenib showed the survival benefit and better safety compared with sorafenib as the first-line treatment for uHCC. Recently, combination therapies have shown favorable results in patients with HCC. Some studies have shown that molecular targeted drugs combined with anti-PD1 antibodies and TACE exhibit improved anti-tumor efficacy compared with monotherapy. This study aimed to evaluate the efficacy and safety of the combination therapy of donafenib,anti-PD-1 antibodies and TACE as first-line treatments for HCC patients in the real world. Methods: This single-center retrospective study involved patients with histopathologically/cytologically or clinically confirmed HCC at Zhejiang Cancer Hospital between July 2021 and June 2023. Eligible patients were treated with donafenib (100 mg po bid) combined with TACE and anti-PD-1 antibodies until the point of disease progression, death, or intolerable toxicity. The objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) datas of patients were collected and analyzed according to the mRECIST, and the incidence of adverse events (AEs) was evaluated using CTCAE 5.0. Results: There were 34 patients in this study (Table). The median age was 64 years (IQR: 57, 69) at the data cut-off in January 2024, with 94.1% of the population being male and 82.4% having HBV infection. Of these patients, 5(14.7%) were classed as BCLC stage A, 11(32.3%) were classed as BCLC stage B, and 18 (52.9%) were BCLC stage C. The median PFS was 7.9 months (95%CI, 5.6–NA), and median OS was not reached, respectively, the 12-month PFS and OS rates were 46.9% (95%CI: 16.8%-72.5%) and 96.9% (95%CI: 79.8%-99.6%). The ORR and DCR for all patients were 73.5% and 97.1%, respectively, based on both mRECIST (CR 3 [8.8%], PR 22 [64.7%], SD 8 [23.5%]). The surgical conversion rate was 26.5%. Treatment-related adverse events (TRAE) of any grade were observed by 18 patients (52.9%), of which 4 patients (11.8%) had grade 3 TRAE. No grade 4 or 5 TRAE was observed. Conclusions: The study indicated that donafenib combined with TACE and anti PD-1 antibodies exhibited encouraging efficacy and favorable safety profile in patients with HCC. [Table: see text]

Efficacy and safety of triplet nivolumab, relatlimab, and ipilimumab (NIVO + RELA + IPI) in advanced melanoma: Results from RELATIVITY-048.

9504 Background: NIVO (anti–PD-1 antibody) is approved as monotherapy and in combination with either RELA (anti–LAG-3 antibody) or IPI (anti–CTLA-4 antibody) for the treatment of patients (pts) with advanced melanoma. RELATIVITY-048 (NCT03459222) is a phase 1/2, nonrandomized trial evaluating immuno-oncology (I-O) triplets, including NIVO + RELA + IPI, for pts with select solid tumors. This analysis from RELATIVITY-048 focused on NIVO + RELA + IPI use in the advanced melanoma cohort and is the first disclosure from the study. Methods: Pts with advanced melanoma were treated with first-line NIVO 480 mg Q4W + RELA 160 mg Q4W + IPI 1 mg/kg Q8W until progression or unacceptable toxicity. Prior neoadjuvant/adjuvant therapy, including I-O agents, was permitted if completed > 6 mo before enrollment. Pts with controlled brain metastases were allowed to enroll. Primary endpoints were safety and confirmed objective response rate (ORR), disease control rate (DCR), and median duration of response (DOR) per investigator. The secondary endpoint was progression-free survival (PFS) per investigator (median and 6-mo/12-mo rates). Exploratory endpoints included overall survival (OS; median and 12-mo/24-mo rates). Results: In total, 46 pts were treated. Median follow-up was 49.4 mo (range, 0.4–55.0; database lock, Nov. 1, 2023). Median age was 61.0 y, 8.7% had cutaneous acral melanoma, 50.0% were BRAF positive, 73.9% were LAG-3 positive (≥ 1%), 26.1% were tumor cell PD-L1 positive (≥ 1%), and 6.5% had received prior adjuvant therapy. Median duration of treatment was 5.0 mo (range, 0.0–49.0). NIVO + RELA + IPI had a confirmed ORR of 58.7% and a 48-mo OS rate of 71.7% (table). Any-grade and grade 3/4 treatment-related adverse events (TRAEs) occurred in 44 pts (95.7%) and 18 pts (39.1%), respectively. Any-grade TRAEs led to treatment discontinuation in 19 pts (41.3%). Deaths due to TRAEs occurred in 2 pts (4.3%; rectal hemorrhage and dyspnea [n = 1], immune-mediated myositis [n = 1]). Conclusions: In RELATIVITY-048, NIVO + RELA + IPI demonstrated encouraging efficacy, with a confirmed ORR of 58.7% and a 48-mo OS rate of 69.1%. There were no new safety signals with NIVO + RELA + IPI, and the safety profile was generally consistent with I-O combinations. Given the small sample size, additional studies are needed to confirm the efficacy and safety of NIVO + RELA + IPI. Clinical trial information: NCT03459222 . [Table: see text]

Feasibility study of a personalized tumor membrane vesicle vaccine immunotherapy for head and neck squamous cell carcinoma (HNSCC).

e14673 Background: Head and neck cancer exhibits a high degree of heterogeneity, with lack of common therapeutic targets. Our phase 1 clinical trial will evaluate a novel personalized immunotherapy approach using tumor membrane vesicles (TMV) prepared from the patients’ own surgically excised tumor tissue and modifying them by attaching GPI-B7-1 and GPI-IL-12 as immune boosting molecules. This personalized vaccine will then be administered to boost the tumor-specific immunity. We report here the feasibility of developing an effective personalized therapeutic cancer vaccine from surgically collected tumor tissue from patients with HNSCC. Methods: After obtaining informed consent, a total of 10 tumor specimens from 10 patients with HNSCC of various sites were collected (0.29-1.23 grams) and graded for cellularity by a pathologist. Tumor samples were then homogenized using sterile, disposable probes. The homogenate was ultracentrifuged over a sucrose gradient to enrich tumor membrane vesicles (TMV). Yield was evaluated by protein concentration and particle size was assessed by dynamic light scattering. TMV preparations were incorporated with GPI-B7-1 and GPI-IL-12 to generate the TMV vaccine using protein transfer, a spontaneous process. For the in vivo murine studies, TMV vaccine is prepared from murine oral cancer (MOC1) tumors and incorporated with murine GPI-B7-1 and GPI-IL-12. To investigate the protective anti-tumor immune response of TMV vaccine in combination with anti-PD1 antibody therapy, we used established murine oral cancer models. We administered two doses of TMV vaccine to naïve C57BL/6 mice and four doses of anti-PD-1 mAb. Mice were monitored for 21 months and then challenged with MOC1 tumor cells 1 week prior to euthanasia. Spleens were flash frozen in liquid nitrogen and stored in -80oC until RNA is isolated for RNA-seq analysis. Results: The yields of TMV were 2.5 – 5 mg per gram of tumor tissue from four human tumor samples. Further refinement of the TMV production process yielded up to 6 mg of TMV/gram of tumor tissue. All samples passed for incorporation of GPI-B7-1 and GPI-IL-12. GPI-B7-1 is able to bind to a natural ligand, CTLA-4 suggesting it is biologically active. All samples also demonstrated biologic activity for GPI-IL-12 as tested using a reporter cell line for IL-12 and displayed acceptable endotoxin levels in a range of 1-34 EU/mg TMV vaccine. The remaining 6 tumor samples are being processed. RNA-seq data from mouse model suggests that the TMV vaccine showed synergistic activity when combined with anti-PD1 antibody, with enhanced T cell responses. Conclusions: TMV vaccine production is feasible for a phase 1 clinical trial for patients whose resected tumor is at least 0.5 g in weight and 40% cellularity. Data in mice show that TMV vaccine synergizes with anti-PD1 in inducing tumor responses.

A phase 1 dose-escalation and expansion study of an intratumorally administered dual STING agonist (ONM-501) alone and in combination with cemiplimab in patients with advanced solid tumors and lymphomas.

TPS2693 Background: The Stimulator of Interferon Genes (STING) pathway has garnered significant interest as a target for anticancer interventions due to its role in driving the production of pro-inflammatory cytokines and activating tumor-specific cell killing. Cyclic dinucleotides (CDNs) such as cGAMP, the endogenous STING agonist, are not ideal clinical candidates for exogenous routes of delivery. Early trials showed limited efficacy with CDNs due to rapid clearance, degradation and/or off-target toxicity. ONM-501 is comprised of a STING-activating pH-sensitive PC7A polymer conjugated with cGAMP. At physiologic pH, ONM-501 forms a micelle, preventing degradation of cGAMP. In the acidic tumor microenvironment, ONM-501 effects STING agonism through a multi-faceted mode of action: 1) endocytosis of nanoparticles and pH-activated micelle dissociation and payload release in endolysosomes enhances intracellular delivery of cGAMP 2) the combination of cGAMP canonical binding, and PC7A polymer noncanonical binding on STING yields synergistic STING activation and 3) stabilization of STING by PC7A polymers delays its degradation and prolongs STING activation. In pre-clinical models, these factors combine to help generate a stronger and more prolonged innate immune response that more effectively translates to a robust adaptive immune response. ONM-501 is being investigated in this first-in-human Phase 1 trial as monotherapy and combination therapy with the anti-PD1 antibody, cemiplimab, for patients with solid tumors and lymphomas. Methods: ONM5001 (NCT06022029) is a first-in-human, open-label, multi-center clinical trial. Adult patients with solid tumors or lymphomas for which no standard therapy exists or for which patients decline palliative standard therapy who have at least one injectable lesion are eligible for this study. This Phase 1 study consists of three parts: monotherapy dose escalation; combination therapy dose finding; and combination therapy dose expansion in specific tumor indication(s) that will be selected based on data from mono- and combination therapy dose finding. Each dosing cycle of ONM-501 is 21 days: patients receive an intratumoral injection of ONM-501 weekly for three weeks, followed by three weeks without injection. Cemiplimab is administered intravenously during combination therapy arms according to standard administration protocol, once every three weeks. The primary endpoint is to evaluate safety of ONM-501 monotherapy as evidenced by the number of dose limiting toxicities and treatment-emergent adverse events, and to determine the recommended dose for expansion. Secondary endpoints include characterization of pharmacokinetics and pharmacodynamics, as well as initial efficacy based on RECIST evaluation criteria. Enrollment began in November 2023. Clinical trial information: NCT06022029 .

Interchangeability of anti-PD1 antibodies in patients (pts) with metastatic NSCLC.

e20553 Background: PD-(L)1 inhibitors are approved immunotherapy agents in treatment for mNSCLC, however, limited data exists about switching between different anti-PD1 antibodies. Our study aimed to evaluate the safety and efficacy of the interchangeability of nivolumab, pembrolizumab, and atezolizumab in patients (pts) with mNSCLC in the 2nd and 3rd line. Methods: We retrospectively evaluated data of pts with mNSCLC treated in four oncology centers in Moscow and SaintPetersburg (Russia). Inclusion criteria were as follows: histologically confirmed mNSCLC with no driver mutations, performance status ECOG 0-2, monotherapy of anti-PD(L)1 antibody, and switching to another PD(L)1 inhibitor for any reason except progression disease or toxicity after initiating of immunotherapy. The primary end-point was progression-free survival (PFS), and secondary end-points were the rate of all grades and grade 3-4 adverse events (CTC AE 5.0). A sample size of 83 achieves 80% power to detect an equivalence difference of 15% in 3-months PFS after the change of anti-PD1 antibody with a one-sided significance level of 0,05. Results: A total of 103 patients (27% female) were included with a mean age of 66 years (33-93). 0-1, 2, and ≥3 organs with metastases have 70 (68%), 17 (17%), and 16 (16%) pts, respectively. Performance status ECOG 0, 1, and 2 was in 16 (16%), 70 (68%), and 17 (17%) pts, respectively. 50 (48%) patients received pembrolizumab, 40 (39%) pts received nivolumab, and 13 (13%) pts – atezolizumab. 48 (47%) pts were switched to atezolizumab, 28 (27%) pts were switched to nivolumab, 26 (25%) pts – to pembrolizumab. The median duration of treatment with the first anti-PD(L)1 antibody was 6 months (1-53 months), with the second PD(L)1-inhibitor was 3 months (1-41 months). Within 3 months after 1 replacement of the drug, there were 77 (74,7%) pts without progression. With the median follow-up of 8 months (1-41), the estimated 3-month PFS was 79,3%. The efficacy of switching was not associated with the agent (HR 0,97, 95CI 0,68-1,38, p = 0,9). There were 2 cases of AEs of 3-4 grades when switching to the second drug. Conclusions: Switching from one anti-PD(L)1 antibody to another in pts with mNSCLC is possible in case of limited access to PD(L)1 inhibitors.

Biomarker analysis and updated clinical outcomes: Neoadjuvant systemic treatment (NST) with nivolumab (nivo) and relatlimab (rela) in surgically resectable melanoma.

9587 Background: NST with immune checkpoint blockade (ICB) improves clinical outcomes over upfront surgery followed by adjuvant treatment (tx) in patients (pts) with stage III, surgically resectable melanoma. The NST platform also provides an opportunity for deep translational analysis to identify baseline (BL) biomarkers predicting pathologic response and to gain insights into resistance. BL biomarkers, including gene expression signatures (GES) such as IFN-γ/ tumor mutational burden, tumor infiltrating lymphocytes, and presence of tertiary lymphoid structures, have been associated with pathologic response to NST with anti-PD1 and/or anti-CTLA4 antibodies. These studies have not evaluated the newest ICB combination, nivo (anti-PD1) + rela (anti-LAG3), which achieved a major pathologic response rate (MPR) (≤10% viable tumor) of 63% in a Ph II study (NCT02519322). Here we report GES analysis from BL and longitudinal tumor tissues obtained on this study and correlations with outcomes. Methods: Longitudinal tissue was collected from 30 pts treated on the clinical trial and available RNA analyzed using the NanoString nCounter PanCancer IO360 panel. Clinical outcomes, including recurrence and event-free survival, were also updated with longer follow-up. Pts were grouped into MPR and non- major pathologic responders (non MPR). Normalization, differential expression / GES evaluation was performed using nSolver Advanced Analysis software. Differential expression is fit on a per signatures basis using a linear model for analysis. P-values were adjusted within each analysis and on the grouping variable level difference t-test using the Benjamini and Yekutieli False Discovery Rate adjustment to account for correlations amongst the tests. BL analysis was grouped based on pathologic response, MPR vs non-MPR. Results: Of the 30 pts (median follow up 44 months), 53 RNA samples from 26 patients (9 NR and 17 R) were included in the full analysis. Immune GES with significantly higher (adjusted p< 0.05) differences at BL in MPR vs non-MPR included: B cells, CD45, CD-8+ T cells, TIGIT, IDO1, and IFN-γ. Significantly higher B7-H3 GES at BL was associated with non MPR. Additional analyses (i.e., cell population changes over time) and association with event outcomes are underway. Conclusions: To our knowledge, this is the first longitudinal RNA analysis reported from pts treated with nivo+rela. BL immune features associated with major pathologic response include higher GES of B cells, CD45+ cells, CD8 T cells, and increased expression of TIGIT, IDO and IFN-y. Additionally, higher B7-H3 in non MPR pts may indicate a clinically actionable strategy for further evaluation. Ongoing analyses of longitudinal samples and correlations with clinical outcomes are underway and will be presented. Clinical trial information: NCT02519322 .

Intravesical local administration of pembrolizumab for treatment of bladder cancer: A novel strategy to minimize toxicity.

e14687 Background: A major hallmark of bladder cancer (BCa) is a higher treatment success rate than prostate cancer following stimulation of innate anti-tumor immune response either by intravesical BCG or to FDA approved intravenous anti-PD1 checkpoint antibody (pembrolizumab) approved for BCG resistant BCa since 2021. However, injected pembrolizumab is characterized by a markedly higher incidence (66%) of serious adverse events than the median duration of complete response of ~40% for non-muscle invasive BCa (NMIBC) and 15-20% for invasive BCa. Since the toxicity (fatigue, Pneumonitis and diarrhea) of injected pembrolizumab is linked to systemic breakdown of T-cell mediated immune surveillance we enquired whether analogous to BCG, pembrolizumab can be administered intravesically to safely induce a localized anti-tumor response in mouse model of BCa. Methods: Six weeks old female mice of B6D2F1 strain (n=10) were ad libitum fed carcinogen, N-butyl-N-4-hydroxybutyl nitrosamine (BBN) in drinking water (0.05% w/v) for 12 weeks. The presence of BBN evoked tumor was ascertained by unenhanced T2 weighted MRI at week 11 prior to single intravesical dosing by 24G transurethral catheter under isoflurane anesthesia of 0.1mL vehicle (sterile water) with or without 0.3mg of Pembrolizumab (Lipella Pharmaceuticals). 6 weeks later, T2 weighted MRI was repeated together with T1 mapping by ICE-MRI prior to organ harvest. Results: BBN feeding evoked multiclonal tumors (red*) of comparable size on T2 weighted MRI at week 11 but repeat MRI 7 weeks after treatment revealed that tumor progression and perivesical invasion noted in vehicle group was arrested in pembrolizumab group. Longest dimension of BBN tumor in vehicle treated mice was ≥ 1mm longer (p<0.05) than in pembrolizumab treated mice. T1 mapping revealed thickened bladder wall missed by T2 MRI. Conclusions: These findings on single intravesical dose of pembrolizumab (10mg/kg) in mice are consistent with human study on multiple intravesical dosing of BCG plus pembrolizumab (1-2mg/kg) in BCG resistant NMIBC patients. Intravesical pembrolizumab mirrors the limited systemic uptake of radiolabelled antibodies together with substantially higher ingress into tumor foci. The tumor selective ingress for BCa immunotherapy without any toxicity will be enhanced with Lipella Pharmaceutical’s liposomal delivery of Pembrolizumab.

Effect of 1-L-MT on immunotherapy of diffuse large B-cell lymphoma via downregulation of PD-L1.

e19066 Background: Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma, accounting for more than 30% of all cases. Although with the development of treatment, the 5 years overall survival rates remain low, range from 30%-50% for all DLBCL patients. In addition to R-CHOP, immunotherapy has attracted much attention. However, the single-agent activity of most immune checkpoint inhibitors (ICI) in DLBCL has been overwhelmingly disappointing. It is urgent to develop new methods to enhance the efficacy of DLBCL treatment. Our previous study demonstrated that 1-L-MT, an IDO1 inhibitor, can inhibit tumor growth of DLBCL. Here, we investigate whether 1-L-MT promotes antitumor immunity of ICI in DLBCL. Methods: The role of 1-L-MT on cell proliferation in vitro and tumor growth in NOD/SCID mice were investigated. RNA-seq analysis was performed in 1-L-MT treated and control OCI-Ly10 cells. ChIP assay was performed using AhR-precipitated DNA samples of OCI-Ly10 cells (treated with or without 1-L-MT) and primers for PD-L1, and he expression of PD-L1 was evaluated by RT-qPCR. The combination of 1-L-MT and PD-1 blockade therapy were performed in C57BL/6 mouse bearing tumor cells to evaluate the antitumor activity. Results: In our study, IDO1 inhibitor 1-L-MT sensitized diffuse large B cell lymphoma to immunotherapy via downregulation of PD-L1. Further study confirmed that 1-L-MT could reduce the expression of PD-L1 and upregulate the expression of MHC-I antigen presentation factors. In addition, RNA-seq and bioinformatics analysis revealed that the transcription factor AhR may involved in the downregulation of PD-L1 transcription level induced by 1-L-MT. Mechanistically, ChIP and RT-qPCR assays were conducted to test AhR-PD-L1 interaction, and the results showed that AhR directly bound the promoter of PD-L1. 1-L-MT-mediated PD-L1 reduction promoted T cell activation and T cell killing of tumor cells. The combination of 1-L-MT and anti PD-1 antibody significantly inhibited DLBCL growth and extends the lifespan of tumor-bearing mice. Conclusions: Our study unveiled a mechanism by which 1-L-MT induces PD-L1 downregulation via AhR and provides methods to facilitate immunotherapy in diffuse large B-cell lymphoma. The present study may provide a theoretical foundation for overcoming the challenge of low-sensitivity to immunotherapy in DLBCL.

Adjuvant therapy with donafenib plus anti–PD-1 antibody for patients (pts) with hepatocellular carcinoma (HCC) at high risk of recurrence after resection (PATH study).

e16228 Background: There is no universally accepted standard treatment option or strategy for post-surgery adjuvant therapy for HCC. Among BCLC A/B patients with MVI, adjuvant TACE provided a 1-year recurrence-free survival rate (RFSR) of around 60-70%. We conducted a pilot study to explore the utility of donafenib combined with anti-PD-1 antibody as adjuvant therapy for pts with high risks of recurrence. Methods: It was planned to enroll 30 HCC pts who had undergone radical surgery and with at least one of the following risk factors: a) Presence of microvascular invasion (MVI); b) Presence of satellite nodule(s); c) > 3 tumor nodules; d) Portal vein tumor thrombus. Pts with invasion of main portal venous were excluded. Donafenib plus anti-PD-1 antibody was initiated at 4 to 8 weeks after resection and continued for up to six months. No other adjuvant therapies were allowed before enrollment and during the study, except for anti-virus treatment. The primary endpoint was the cumulative 1-year RFSR. The secondary endpoints included recurrence-free survival (RFS), overall survival, and safety. Results: From June 2020 to November 2023, a total of 30 pts were recruited. 27 pts were included in efficacy analysis. The mean and median follow-up time was 347.9 days and 179.5 days. The mean and median time from surgery to enrollment was 42.5 days and 42.0 days. MVI was the most common risk factor (Table). Majority of the pts had only one risk factor. Relapse occurred in two pts (7.4%) and RFS was very immature. The RFSR at one year was 89.7% (90% CI, 70.6%-96.7%) in all the evaluable pts, and slightly higher in pts with M1 or only one risk factor (92.9% [90% CI, 68.1%-98.6%] and 93.3% [90% CI, 69.9%-98.7%], respectively). No deaths were observed. In 30 pts who had received at least one dose, the incidence of grade 3 treatment-related adverse events (TRAEs) was 40.0% (12/30). No grade 4 or 5 TRAEs were reported. The grade 3 TRAEs occurred in ≥2 pts were palmar-plantar erythrodysesthesia syndrome (13.3%), rash (13.3%), alanine aminotransferase increased (10.0%), and aspartate aminotransferase increased (6.7%). Conclusions: These results showed that a regimen of 6 months of adjuvant therapy with donafenib plus anti-PD-1 antibody may be efficient to reduce recurrence for BCLC A/B pts at high risk of recurrence, particularly those with ≤2 risk factors. No new safety issues were noticed. Clinical trial information: NCT04418401 . [Table: see text]

Validation of HLA presented tumor-exclusive peptides in an independent cohort of head and neck squamous cell carcinoma.

6047 Background: Response rates to anti-PD1 antibodies in head and neck squamous cell carcinoma (HNSCC) range from 13-20% in recurrent / metastatic disease and up to 50% in locoregionally advanced disease. Vaccines composed of tumor-exclusive antigens may increase response rates to immunotherapy. We have previously identified HLA-presented tumor-exclusive peptides (TEP) in a cohort of 40 oropharyngeal HNSCC (UL dataset) and defined a warehouse of HLA allotype specific TEP (EP2023/071063, patent pending) for semipersonalized vaccine composition for 15 HLA allotypes. Methods: The HLA-bound immunopeptidome of a validation cohort of 40 HNSCC from Tübingen University was analyzed by tandem mass spectrometry (TÜ dataset). Data were processed as previously described to identify TEP. The TÜ dataset was queried for TEP from the previously defined warehouse containing 48 TEP for the respective 15 HLA allotypes in a cohort of 40 oropharyngeal HNSCC (UL dataset) patient samles. Coverage was defined as the fraction of patients presenting at least one of the TEP for a certain HLA allotype. Results: Among all 80 patients, 75 had at least one of the 15 HLA allotypes (36 in the TÜ cohort and 39 in the UL cohort). Of the 48 TEP, 28 TEP for 11/15 HLA allotypes were found in the TÜ validation cohort. The best coverages with the warehouse TEP were found for the following four HLA allotypes: HLA-A*01:01 (TÜ: 91%; UL: 79%), A*02:01 (TÜ: 81%; UL: 52%), B*40:01 (TÜ: 63%; UL: 100%) and A*24:02 (TÜ: 60%; 44%.). Based on a semipersonalized TEP selection by HLA allotype, 27/40 patients in the TÜ cohort presented at least one of the TEP selected (range: 0-10), whereas 28/40 patients in the UL cohort presented at least one of the TEP (range: 0-7). Thus, the total cohort coverage based on a semipersonalized peptide selection was 55/80 patients (68.8%). Conclusions: We validated previously identified TEP from oropharyngeal HNSCC for frequently occurring HLA allotypes in an independent, equally sized cohort of HNSCC patients. A semipersonalized vaccine composition strategy using a warehouse / off-the-shelve approach for immunotherapy trials seems feasible.

Combining the potency of a neoantigen-expressing DNA vector, an anti-CTLA-4 antibody, and an attenuated poxvirus in a personalized immunization platform: Preclinical studies of ODI-2001.

e14674 Background: Immune checkpoint inhibitors (ICI) have transformed cancer treatment. Their impressive effectiveness is crucially dependent on pre-existing neoepitope-specific immune responses. ODI-2001 aims at increasing the immune response against tumors by combining a DNA expressing multiple neoepitopes of the tumor, a MVA vaccinia virus as physiologic adjuvant and DNA carrier, and an anti-CTLA4 antibody as amplifier of the immune response. Methods: ODI-2001 was administered by repeated subcutaneous injections after tumor cells implantation in mice melanoma model B16F10 and colorectal cancer model CT26, and both before and after implantation in breast cancer model 4T1. In B16F10 model combination of ODI-2001 with anti-PD1 was assessed also. Neoepitopes were chosen from literature in B16F10 and CT26 models. In 4T1 model they were predicted using a dedicated neoepitope prediction algorithm (ImmunoEngine, myNEO, Gent, Belgium). Tumor volume and mice survival were assessed over time. Tumors were also analysed by immunofluorescence for immune cell infiltration. Each experiment received approval from the ethics committee for animals. Results: A significant improvement in survival was observed in mice treated with ODI-2001 in B16F10, and CT26 syngeneic mice models. In B16F10 the combination of ODI-2001 with anti-PD1 antibody demonstrated synergistic activity and a significant improvement in survival, while anti-PD1 alone or combined with anti-CTLA-4 failed to show any therapeutic effect (ODI-2001 + anti-PD1 vs. anti-CTLA-4 + anti-PD1 p<0.01). ODI-2001 treatment was associated with tumor rejections in the three animal models. In 4T1 model the ImmunoEngine epitope prediction algorithm demonstrated an improved efficacy as compared to a set of neoepitopes chosen from the literature. In B16F10, following immunization with ODI-2001, an increased CD8 immune cell infiltration of the tumor was documented. ODI-2001 was well tolerated by the treated animals. Conclusions: These data demonstrate a significant antitumoral activity of ODI-2001 as a neoantigen immunization platform across different preclinical cancer models, both in monotherapy and combined with anti-PD1. ODI-2001 represents a promising option to induce de novo cancer-specific immune responses, potentially increasing the proportion of patients responding to immunotherapy treatments. Based on this preclinical program a phase I with ODI-2001 in patients with advanced colorectal carcinoma is currently under preparation.

Expand and pull: A new treatment paradigm for glioblastoma using a long-acting recombinant interleukin-7 and oncolytic viral therapy.

2043 Background: Patients with glioblastoma (GBM) face three major challenges. First, the tumor itself as well as chemoradiation treatment result in lymphopenia, which is associated with shorter survival. Second, the tumor microenvironment (TME) has a paucity of T cells and consequently, immunotherapies have failed in multiple phase 3 clinical trials for GBM. Third, a treatment resistant population of cancer stem cells (CSCs) contribute to inevitable tumor recurrence. In preclinical models, we have shown that a long-acting IL-7, NT-I7, significantly increases peripheral CD8 T cells and separately, oncolytic Zika virus (ZIKV) directly targets CSC and induces an anti-tumor CD8 T cell response. The aim of this study was to determine whether we can leverage the NT-I7 driven T cell expansion peripherally and combine it with ZIKV therapy to pull immune cells into the TME to successfully treat a highly immunosuppressive mouse model of GBM. Methods: SB28 syngeneic tumor cells were intracranially implanted in C57BL/6J mice. Mice were treated with NT-I7 subcutaneously on days 7 and 10 post tumor implantation, followed by intratumoral ZIKV on day 14. Mice were monitored for survival and bled weekly to assess the systemic T-cell response to NT-I7. Immunoprofiling of brain, draining lymph node, and peripheral blood via flow cytometry was done on days 17 and 21. Results: NT-I7 significantly expanded peripheral T cells compared to control (5,623 cells/µL vs 136 cells/µL, p<0.05). Cytotoxic CD8 T cells were particularly increased (4,776 cells/µL vs 47 cells/µL, p<0.05), with the expansion peak at day 7 after the first dose of NT-I7 and persisting for 21 days. When ZIKV was administered at the peak of the NT-I7-driven CD8 T cell expansion, the combination resulted in significant improvement in survival compared to NT-I7 or ZIKV monotherapy (median 47 days vs 35 days and 33 days, respectively, p<0.05). Combined NT-I7 and ZIKV treatment significantly increased TME CD8 T cell infiltration (369,814 cells/g vs 23,947 cells/g and 63,961 cells/g, respectively) as well as increased expression of interferon-γ, TNF-α, perforin, and granzyme B (p<0.05). Long-term survivors were protected against tumor rechallenge, suggesting that this treatment strategy confers immune memory against tumor antigens. The addition of immune checkpoint blockade with anti-PD1 antibody resulted in nearly 80% complete tumor clearance. Conclusions: Timing the oncolytic ZIKV injection with the NT-I7-induced peak expansion of peripheral CD8 T cells greatly increased tumor infiltration of cytotoxic T cells and improved survival in the immunotherapy resistant SB28 glioma model. This work suggests a new “expand and pull” approach for the treatment of highly immunosuppressive tumors such as GBM: priming the systemic immune system with NT-I7, followed by an oncolytic stimulus to draw them into the TME to engage and clear tumor cells.

Synergistic effects of Smac mimetic APG-1387 with anti-PD-1 antibody are attributed to increased CD3 + NK1.1 + cell recruitment secondary to induction of cytokines from tumor cells

BackgroundImmune checkpoint inhibitors are approved for the treatment of various tumors, but the response rate is not satisfactory in certain malignancies. Inhibitor of apoptosis proteins (IAP) ubiquitin-E3 ligase activity is involved in the regulation of immune responses. APG-1387 is a novel second mitochondria-derived activator of caspase (Smac) mimetic IAP inhibitor. The aim of this study was to explore the synergistic effect of APG-1387 when combined with anti-PD-1 antibody in a preclinical setting.MethodsWe utilized syngeneic mouse models of ovarian cancer (ID8), colon cancer (MC38), malignant melanoma (B16), and liver cancer (Hepa1-6) to assess the combination effect of APG-1387 and anti-PD-1 antibody, including immune-related factors, tumor growth, and survival. MSD V-PLEX validated assays were used to measure in vitro and in vivo cytokine release.ResultsIn ID8 ovarian cancer and MC38 colon cancer models, APG-1387 and anti-PD1 antibody had synergistic antitumor effects. In the MC38 model, the combination of APG-1387 and anti-PD-1 antibody significantly inhibited tumor growth (P < 0.0001) and increased the survival rate of tumor-bearing animals (P < 0.001). Moreover, we found that APG-1387 upregulated tumor-infiltrating CD3 + NK1.1 + cells by nearly 2-fold, by promoting tumor cell secretion of IL-12. Blocking IL-12 secretion abrogated the synergistic effects of APG-1387 and anti-PD-1 antibody in both MC38 and ID8 models.ConclusionsAPG-1387 has the potential to turn “cold tumors” into hot ones by recruiting more CD3 + NK1.1 + cells into certain tumors. Based on these and other data, the safety and therapeutic effect of this combination will be investigated in a phase 1/2 trial in patients with advanced solid tumors or hematologic malignancies (NCT03386526).Graphic abstract

Abstract RF01-06: Efficacy and safety of toripalimab plus metronomic chemotherapy in HER2 negative metastatic breast cancer: a multicenter phase II trial based on a Bayesian adaptive randomized design

Abstract Background: Combining Immune checkpoint blockade (ICB) with chemotherapy may significantly improve efficacy in patients with breast cancer. Metronomic chemotherapy is based on more frequent and low-dose drug administrations compared with conventional chemotherapy. Some clinical studies with small samples have tried the combination of metronomic chemotherapy and ICB in patients with advanced tumors. However, whether metronomic chemotherapy is more suitable for ICB than conventional chemotherapy is still unclear. Thus, we performed the first clinical trial, to our knowledge, of metronomic chemotherapy combined with PD-1 blockade comparing with the efficacy of combined conventional chemotherapy and ICB. Methods: This study is a multicenter randomized phase 2 trial using a multi-arm design with Bayesian adaptive randomization and efficacy monitoring. Eligible patients have advanced HER2 negative breast cancer, with no more than one prior line of standard chemotherapy. Patients were randomized to 5 groups: ① metronomic vinorelbine (NVB, 40 mg/day, TIW) monotherapy (the control cohort); ② NVB + Toripalimab (anti-PD1 antibody, 240 mg Q3W); ③Bevacizumab (5 mg/kg Q3W) + NVB+ Toripalimab (the BEV cohort); ④ Cisplatin (50mg/m Q3W) + NVB + Toripalimab (the DDP cohort), ⑤Cyclophosphamide (50mg/day, QD) + Capecitabine (500 mg, TID) + NVB+ Toripalimab (the VEX cohort). The primary endpoint is disease control rate (DCR), and secondary endpoints are objective response rate (ORR), progression free survival (PFS), and overall survival (OS). The safety profile has also been assessed. Mass cytometry time-of-flight (CyTOF) analyses of paired blood samples were performed to demonstrate dynamic changes in systemic immune profile. Results: A total of 103 patients were randomized. Characteristics were as expected for advanced breast cancer and balanced between cohorts. Adverse events of any grade occurred in 64 patients, with 5.2% grade &amp;gt;3. The rate of nausea was significantly higher in the cisplatin cohort than in the others (P&amp;lt; 0.001). Toripalimab was not associated with any previously unreported toxicity. Among the five treatment cohorts, the VEX cohort and the cisplatin cohort had the highest DCR, 69.7% (95% CI 51.7–85.9%) and 73.7% (95% CI 56.1–88.7%), respectively. Followed by the bevacizumab cohort, DCR is 55.7% (95% CI 37.4%–73.6%). Most objective responses were observed in the VEX cohort (ORR: 18.5%; 95% CI 5.6–34.1%), followed by cisplatin (ORR 14.5%; 95% CI 3.3–29.0%). It is worth noting that the PFS of patients in the VEX cohort was the longest, reaching 6.6 months (95% CI 4.0-5.9), followed by 4.0 months (95% CI 2.4-10.4) in patients of the bevacizumab cohort. The PFS of patients receiving the cisplatin regimen was relatively short, only 3.5 months (95% CI 2.2-5.3). Similarly, patients in the cisplatin cohort had shorter OS than those in the VEX and bevacizumab cohorts. In the TNBC subgroup, again, patients in the VEX cohort had the highest DCR (74.1%, 95%CI 47.9%-95.4%) and longest PFS (9.8 months, 95%CI 3.8-21.9). We obtained over 63 million cells in total and clustered CD45+ immune cells into 32 clusters. The systemic immune profile of patients changed dramatically over 2 cycles of PD-1 blockade. However, only the change of cluster 30 differed between responders and non-responders. This is a group of intermediate monocytes with a high expression of CD38, which decreased in responders but significantly increased in non-responders. CD38-NAD+ axis regulates the PD1+ exhausted T cell function. Meanwhile, the overall expression of CD38 in monocytes was significantly increased by DDP and BEV treatment compared with baseline, but not in the VEX groups. DDP significantly increased the expression level of CD38 on NK cells, while BEV or VEX treatment did not affect it. Conclusions: These data suggest promising clinical efficacy and evidence of cooperativity between metronomic VEX chemotherapy and PD-1 blockade. Citation Format: Hongnan Mo, Xiaoying Sun, Jingtong Zhai, Jiashu Han, Hewei Ge, Yuhan Wei, Xiuwen Guan, Haili Qian, Fei Ma. Efficacy and safety of toripalimab plus metronomic chemotherapy in HER2 negative metastatic breast cancer: a multicenter phase II trial based on a Bayesian adaptive randomized design [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 RF01-06.

Clinical and Biomarker Analysis of a Phase I/II Study of PDR001 Plus Imatinib for Advanced Treatment-Refractory Gastrointestinal Stromal Tumors.

In this phase Ib/II study, we aimed to evaluate the safety and efficacy of PDR001, an anti-PD1 antibody, in combination with imatinib in patients with treatment-refractory gastrointestinal stromal tumor (GIST). Patients with advanced GIST whose disease had progressed on imatinib, sunitinib, and regorafenib were enrolled. In phase Ib, the standard 3 + 3 dose escalation scheme was applied. Intravenous administration of PDR001 at 400 mg for every 4 weeks plus imatinib (300 and 400 mg daily for dose levels I and II, respectively) was given. The primary outcome for phase II was the disease control rate at 12 weeks. Exploratory biomarker analysis was performed based on PDL1 IHC, next-generation sequencing, and multiplexed IHC. No dose-limiting toxicity was observed in the phase Ib part (n = 10), and dose level II was selected as the recommended phase II dose. In the phase II part (n = 29), there was no objective response, and the disease control rate at 12 weeks was 37.9%, not meeting the primary efficacy endpoint. For patients in phase Ib-dose level II and phase II (n = 36), the median progression-free survival (PFS) and overall survival were 2.3 and 9.5 months, respectively. The most common grade 3 to 4 adverse event was anemia. Exploratory biomarker analysis indicated that a higher CD8+ T-cell density was associated with a favorable PFS but to a limited degree. Tumor mutational burden and PDL1 were not associated with better PFS. In patients with treatment-refractory GIST, PDR001 in combination with imatinib was generally tolerable, but it was not effective.

Intratumor injection of BCG Ag85A high-affinity peptides enhanced anti-tumor efficacy in PPD-positive melanoma

As one of the scheduled immunization vaccines worldwide, virtually all individuals have been vaccinated with BCG vaccine. In order to verify the hypothesis that delivering BCG high-affinity peptides to tumor areas could activate the existing BCG memory T cells to attack tumor, we firstly predicted the HLA-A*0201 high-affinity peptides of BCG Ag85A protein (KLIANNTRV, GLPVEYLQV), and then, A375 melanoma cells and HLA-A*0201 PBMCs (from PPD-positive adults) were added to co-incubated with the predicted peptides in vitro. We found that the predicted BCG high-affinity peptides could be directly loaded onto the surface of tumor cells, enhancing the tumor-killing efficacy of PBMCs from PPD-positive volunteer. Then, we constructed PPD-positive mice model bearing B16F10 subcutaneous tumors and found that intratumor injection of BCG Ag85A high-affinity peptides (SGGANSPAL, YHPQQFVYAGAMSGLLD) enhanced the anti-tumor efficacy in PPD-positive melanoma mice. Along with the better anti-tumor efficacy, the expression of PDL1 on tumor cell surface was also increased, and stronger antitumor effects occurred when further combined with anti-PD1 antibody. For microenvironment analysis, the proportion of effector memory T cells was increased and the better treatment efficacy may be attributed to the elevated effector memory CD4 + T cells within the tumor. In conclusion, using the existing immune response of BCG vaccine by delivering high-affinity peptides of BCG to tumor area is a safe and promising therapy for cancer.

Abstract CT134: Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma

Abstract Background: Strategies are needed to improve effectiveness of immunotherapy in pancreatic ductal adenocarcinoma (PDA). Our recently published study (NCT02648282) showed that increased M1/M2 ratio and decreased PDL1+ M2-like tumor associated macrophages (TAM) in locally advanced PDA is associated with longer overall survival (OS) following combination of stereotactic body radiotherapy, GVAX and anti-PD1 antibody pembrolizumab (Pem). We hypothesized targeting M2-like macrophages, regulated by the colony stimulating factor-1 (CSF1) pathway, would improve outcomes. In this pilot study we investigated the safety and intratumoral immune response of neoadjuvant/adjuvant triplet immunotherapy: GVAX/cyclophosphamide (CY), Pem, and CSF1 receptor blockade (IMC-CS4) in patients with resectable or borderline resectable PDA. Methods: After completing chemotherapy and radiation patients received two 3-week cycles of neoadjuvant triplet immunotherapy. Following surgery, patients received 4 additional cycles followed by booster Pem every 3 weeks and GVAX/CY every 6 months, for one year. Co-primary endpoints were safety, assessed by NCI Common Terminology Criteria for Adverse Events (AEs), and immune response (increased CD8+ T-cell density in surgical specimen as compared to pre-treatment core). Secondary endpoints included disease free survival (DFS), OS, surgical resectability, and pathologic response (PR). Results: Nine patients were enrolled. Two immune related grade 3/4 AEs (diarrhea and rash) were reported. Median DFS was 12.6 months (95% CI: 7.3, NR) and median OS was 20.4 months (95% CI: 17.5, NR). All patients underwent surgery with major PR rate of 78% (defined as &amp;lt;10% residual viable tumor), including one complete PR. Comparing paired biopsies, the study met its primary immunologic endpoint showing 6/8 patients (75%) had a &amp;gt;80% increase of CD8+ T cells; the increase was at least 1.8 times the baseline median absolute deviation following triple therapy (p=0.012). There was a significant increase of Granzyme B+ CD8+ T cells among all patients (p=0.045). No significant change in myeloid cell density, including TAM, was observed, suggesting IMC-CS4 did not deplete macrophages, but potentially reprogrammed them. The 4 patients with greatest drop in CD66b+ granulocyte levels had major PR (grade 0 or 1). Conclusion: The triplet was safe and significantly increased activated CD8+ T cells suggesting the combination can induce an effector T cell response. Decreased granulocyte levels correlated with PR. Citation Format: Arielle Urman, Yingjun Ding, Hao Wang, Richard A. Burkhart, Jin He, Elizabeth M. Jaffee, Amol K. Narang, Dung Le, Daniel A. Laheru, Lei Zheng, Ana De Jesus-Acosta. Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma [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 CT134.

Induction of Immunological Antitumor Effects by the Combination of Adenovirus-Mediated Gene Transfer of B7-1 and Anti-Programmed Cell Death-1 Antibody in a Murine Squamous Cell Carcinoma Model.

The goal of this study was to evaluate the antitumor immune effects of B7-1 gene expression in addition to immune checkpoint inhibitor against squamous cell carcinoma. A murine SCC cell line, KLN205, was infected with adenoviral vector carrying B7-1 (AdB7). Infected cells were injected subcutaneously in the flanks of DBA/2 mice. Three weeks after implantation, anti-mouse PD-1 antibody (antiPD1) was intraperitonially administrated twice a week for a total of six times. CD80 was significantly overexpressed in the AdB7-infected tumors. IFN-gamma in the T cells in the spleen was significantly increased and tumor size was significantly reduced in the mice treated with both AdB7 and antiPD1. Targeted tumors treated with both AdB7 and antiPD1 exhibited significantly increased cell densities of total immune cells as well as Ki-67+ CD8+ T cells and decreased regulatory T cells. These results suggest that the B7-1 gene transfer may enhance the antitumor effect of anti-PD1 antibody against SCC.

Intravenous administration of IL-12 encoding self-replicating RNA-lipid nanoparticle complex leads to safe and effective antitumor responses

Interleukin 12 (IL-12) is a potent immunostimulatory cytokine mainly produced by antigen-presenting cells (e.g., dendritic cells, macrophages) and plays an important role in innate and adaptive immunity against cancers. Therapies that can synergistically modulate innate immunity and stimulate adaptive anti-tumor responses are of great interest for cancer immunotherapy. Here we investigated the lipid nanoparticle-encapsulated self-replicating RNA (srRNA) encoding IL-12 (referred to as JCXH-211) for the treatment of cancers. Both local (intratumoral) and systemic (intravenous) administration of JCXH-211 in tumor-bearing mice induced a high-level expression of IL-12 in tumor tissues, leading to modulation of tumor microenvironment and systemic activation of antitumor immunity. Particularly, JCXH-211 can inhibit the tumor-infiltration of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). When combined with anti-PD1 antibody, it was able to enhance the recruitment of T cells and NK cells into tumors. In multiple mouse solid tumor models, intravenous injection of JCXH-211 not only eradicated large preestablished tumors, but also induced protective immune memory that prevented the growth of rechallenged tumors. Finally, intravenous injection of JCXH-211 did not cause noticeable systemic toxicity in tumor-bearing mice and non-human primates. Thus, our study demonstrated the feasibility of intravenous administration of JCXH-211 for the treatment of advanced cancers.