A Phase 1 Trial of Trebananib, an Angiopoietin 1 and 2 Neutralizing Peptibody, Combined with Pembrolizumab in Patients with Advanced Ovarian and Colorectal Cancer

Ovarian cancers and microsatellite stable (MSS) colorectal cancers (CRC) are insensitive to anti-PD1 immunotherapy, and new immunotherapeutic approaches are needed. Preclinical data suggests a relationship between immunotherapy resistance and elevated angiopoietin 2 levels. We performed a phase 1 dose-escalation study of pembrolizumab and the angiopoietin 1/2 inhibitor trebananib (NCT03239145). This multicenter trial enrolled patients with metastatic ovarian cancer or MSS CRC. Trebananib was administered intravenously weekly for 12 weeks with 200 mg intravenous pembrolizumab every 3 weeks. The toxicity profile of this combination was manageable, and the protocol-defined highest dose level (trebananib 30 mg/kg weekly plus pembrolizumab 200 mg every 3 weeks) was declared the maximum tolerated dose. The objective response rate for all patients was 7.3% (90% confidence interval: 2.5-15.9%). Three patients with MSS CRC had durable responses for ≥3 years. One responding patient's CRC harbored a POLE mutation. The other two responding patients had left-sided CRCs with no baseline liver metastases, and genomic analysis revealed that they both had KRAS wild-type, ERBB2 amplified tumors. After development of acquired resistance, biopsy of one patient's KRAS wild-type, ERBB2 amplified tumor showed a substantial decline in tumor-associated T cells and an increase in immunosuppressive intratumoral macrophages. Future studies are needed to carefully assess whether clinicogenomic features, such as lack of liver metastases, ERBB2 amplification, and left-sided tumors, can predict increased sensitivity to PD1 immunotherapy combinations.

Botensilimab plus balstilimab in relapsed/refractory microsatellite stable metastatic colorectal cancer: a phase 1 trial

Microsatellite stable metastatic colorectal cancer (MSS mCRC; mismatch repair proficient) has previously responded poorly to immune checkpoint blockade. Botensilimab (BOT) is an Fc-enhanced multifunctional anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) antibody designed to expand therapy to cold/poorly immunogenic solid tumors, such as MSS mCRC. BOT with or without balstilimab (BAL; anti-PD-1 antibody) is being evaluated in an ongoing expanded phase 1 study. The primary endpoint is safety and tolerability, which was evaluated separately in the dose-escalation portion of the study and in patients with MSS mCRC (using combined dose-escalation/dose-expansion data). Secondary endpoints include investigator-assessed RECIST version 1.1-confirmed objective response rate (ORR), disease control rate (DCR), duration of response (DOR) and progression-free survival (PFS). Here we present outcomes in 148 heavily pre-treated patients with MSS mCRC (six from the dose-escalation cohort; 142 from the dose-expansion cohort) treated with BOT and BAL, 101 of whom were considered response evaluable with at least 6 months of follow-up. Treatment-related adverse events (TRAEs) occurred in 89% of patients with MSS mCRC (131/148), most commonly fatigue (35%, 52/148), diarrhea (32%, 47/148) and pyrexia (24%, 36/148), with no grade 5 TRAEs reported and a 12% discontinuation rate due to a TRAE (18/148; data fully mature). In the response-evaluable population (n = 101), ORR was 17% (17/101; 95% confidence interval (CI), 10-26%), and DCR was 61% (62/101; 95% CI, 51-71%). Median DOR was not reached (NR; 95% CI, 5.7 months-NR), and median PFS was 3.5 months (95% CI, 2.7-4.1 months), at a median follow-up of 10.3 months (range, 0.5-42.6 months; data continuing to mature). The combination of BOT plus BAL demonstrated a manageable safety profile with no new immune-mediated safety signals and encouraging clinical activity with durable responses. ClinicalTrials.gov identifier: NCT03860272 .

A Large-Scale Proteomics Resource of Circulating Extracellular Vesicles for Biomarker Discovery in Pancreatic Cancer

Pancreatic cancer has the worst prognosis of all common tumors. Earlier cancer diagnosis could increase survival rates and better assessment of metastatic disease could improve patient care. As such, there is an urgent need to develop biomarkers to diagnose this deadly malignancy. Analyzing circulating extracellular vesicles (cEVs) using 'liquid biopsies' offers an attractive approach to diagnose and monitor disease status. However, it is important to differentiate EV-associated proteins enriched in patients with pancreatic ductal adenocarcinoma (PDAC) from those with benign pancreatic diseases such as chronic pancreatitis and intraductal papillary mucinous neoplasm (IPMN). To meet this need, we combined the novel EVtrap method for highly efficient isolation of EVs from plasma and conducted proteomics analysis of samples from 124 individuals, including patients with PDAC, benign pancreatic diseases and controls. On average, 912 EV proteins were identified per 100µL of plasma. EVs containing high levels of PDCD6IP, SERPINA12 and RUVBL2 were associated with PDAC compared to the benign diseases in both discovery and validation cohorts. EVs with PSMB4, RUVBL2 and ANKAR were associated with metastasis, and those with CRP, RALB and CD55 correlated with poor clinical prognosis. Finally, we validated a 7-EV protein PDAC signature against a background of benign pancreatic diseases that yielded an 89% prediction accuracy for the diagnosis of PDAC. To our knowledge, our study represents the largest proteomics profiling of circulating EVs ever conducted in pancreatic cancer and provides a valuable open-source atlas to the scientific community with a comprehensive catalogue of novel cEVs that may assist in the development of biomarkers and improve the outcomes of patients with PDAC.

Exploiting pancreatic cancer metabolism: challenges and opportunities

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive form of pancreatic cancer, known for its challenging diagnosis and limited treatment options. The focus on metabolic reprogramming as a key factor in tumor initiation, progression, and therapy resistance has gained prominence. In this review we focus on the impact of metabolic changes on the interplay among stromal, immune, and tumor cells, as glutamine and branched-chain amino acids (BCAAs) emerge as pivotal players in modulating immune cell functions and tumor growth. We also discuss ongoing clinical trials that explore metabolic modulation for PDAC, targeting mitochondrial metabolism, asparagine and glutamine addiction, and autophagy inhibition. Overcoming challenges in understanding nutrient effects on immune-stromal-tumor interactions holds promise for innovative therapeutic strategies.

A multicenter phase Ia study of AbGn-107, a novel antibody-drug conjugate, in patients with advanced gastrointestinal cancer

AbGn-107 is an antibody-drug conjugate directed against AG-7 antigen, a Lewis A-like glycol-epitope expressed in a variety of gastrointestinal (GI) malignancies. Based on promising antitumor activity of AbGn-107 in both in vitro and in vivo preclinical studies, we performed a GI cancer-specific Phase I trial. Standard 3 + 3 dose escalation was used evaluating intravenous doses ranging from 0.1 mg/kg every 4 weeks to 1.0 mg/kg every 2 weeks. Key eligibility included chemo-refractory locally advanced, recurrent, or metastatic gastric, colorectal, pancreatic, or biliary cancer, with ECOG PS 0-1; positive AG-7 expression was not required during dose escalation phase. Patients were treated until disease progression or unacceptable toxicity, with tumor assessments every 8 weeks. Primary objectives included safety and determination of maximum tolerated dose; secondary objectives included efficacy defined by objective response rate. Thirty-nine patients were enrolled across seven dose levels during dose escalation phase. Based on safety profile and pharmacokinetic data, 1.0 mg/kg Q2W was selected as the dose schedule for cohort expansion phase, in which an additional seven patients were enrolled. Median number of lines of prior therapy was 3 (range 1-7). AbGn-107 was generally well-tolerated, with infections, cytopenias, hyponatremia, fatigue, abdominal pain, and diarrhea representing the most common grade 3 or higher treatment-emergent adverse events. One subject achieved a partial response, while 18 (46.2%) achieved a best response of stable disease. Disease control lasting > 6 months was observed in 6 subjects (13.0%), including 4 of 15 (26.7%) treated at the highest dose level. AbGn-107 showed a reasonable safety profile and modest clinical activity in this highly pretreated patient population. Further evaluation is required to assess the clinical validity of AG-7 as a suitable antigen for therapeutic targeting. Clinical Trial information: NCT02908451.

Results from a phase 1a/1b study of botensilimab (BOT), a novel innate/adaptive immune activator, plus balstilimab (BAL; anti-PD-1 antibody) in metastatic heavily pretreated microsatellite stable colorectal cancer (MSS CRC)

LBA8

Background: BOT promotes optimized T cell priming, activation and memory formation by strengthening antigen presenting cell/T cell co-engagement. As an Fc-enhanced next-generation anti–CTLA-4 antibody, BOT also promotes intratumoral regulatory T cell depletion and reduces complement fixation. We present results from patients with MSS CRC treated with BOT + BAL in an expanded phase 1a/1b study; NCT03860272. Methods: Patients (pts) with metastatic MSS CRC received BOT 1 or 2 mg/kg every 6 weeks (Q6W) + BAL 3 mg/kg every 2 weeks. Crossover from monotherapy to combination therapy was permitted (rescue) as well as fixed-dosing (150 mg BOT Q6W + 450 mg BAL every 3 weeks). Results: Fifty-nine combination pts were evaluable for efficacy/safety (treated as of 19 May 2022 with ≥1 Q6W imaging assessment), including one rescue and one fixed-dose pt. Median pt age was 57 (range, 25-83), 58% were female, and 76% received at least three prior lines of therapy including prior immunotherapy (34%). Median follow-up was 6.4 months (range, 1.6-29.5). In all pts, objective response rate (ORR) was 22% (95% CI, 12-35), disease control rate (DCR) was 73% (95% CI, 60-84), and median duration of response (DOR) was not reached (NR), with 9/13 responses ongoing. The 12-month overall survival (OS) rate was 61% (95% CI, 42-75), with median OS NR. Of the 13 responders, 9 had RAS mutations (7 KRAS, 2 NRAS), 0 had BRAF mutations, 0/10 had a TMB of ≥10 mutations/Mb, and 1/7 was PD-L1 positive (≥1% combined positive score). A subgroup analysis was conducted by the dose of BOT received . In 1 mg/kg pts (n=8), ORR was 38% (3/8; 95% CI, 9-76) and DCR was 100% (8/8; 95% CI, 63-100); in 2 mg/kg pts (n=50), ORR was 20% (10/50; 95% CI, 10-34) and DCR was 70% (35/50; 95% CI, 55-82). All grade treatment-related adverse events (TRAEs) occurred in 88% of pts, including grade 3 in 32%, and grade 4 in 2% of pts. Diarrhea/colitis was the only grade 3/4 TRAE occurring in more than three pts (15% grade 3, 2% grade 4). The most common grade 3 TRAEs outside of diarrhea/colitis were fatigue (5%) and pyrexia (5%). There were no grade 5 TRAEs reported. Fifteen percent of pts had a TRAE leading to discontinuation of BOT alone and 12% had a TRAE leading to discontinuation of both BOT + BAL. Conclusions: In heavily pretreated metastatic MSS CRC pts, BOT + BAL continues to demonstrate promising clinical activity with durable responses and was well tolerated with no new immune-mediated safety signals. A larger pt set, analyses by subgroup, and additional translational data will be presented at the meeting. A randomized phase 2 trial in MSS CRC pts is enrolling (NCT05608044). Clinical trial information: NCT03860272 .

Facts and Hopes in Immunotherapy of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most challenging cancers to treat. For patients with advanced and metastatic disease, chemotherapy has yielded only modest incremental benefits, which are not durable. Immunotherapy has revolutionized the treatment of other solid tumors by leading to cures where none existed only a decade ago, yet it has made few inroads with PDAC. A host of trials with promising preclinical data have failed, except for in a small minority of patients with selected biomarkers. There is, however, a glimmer of hope, which we seek to cultivate. In this review, we discuss recent advances in the understanding of the uniquely immunosuppressive tumor microenvironment (TME) in PDAC, learnings from completed trials of checkpoint inhibitors, TME modifiers, cellular and vaccine therapies, oncolytic viruses, and other novel approaches. We go on to discuss our expectations for improved preclinical models of immunotherapy in PDAC, new approaches to modifying the TME including the myeloid compartment, and emerging biomarkers to better select patients who may benefit from immunotherapy. We also discuss improvements in clinical trial design specific to immunotherapy that will help us better measure success when we find it. Finally, we discuss the urgent imperative to better design and execute bold, but rational, combination trials of novel agents designed to cure patients with PDAC.

Priming of Sorafenib Prior to Radiofrequency Ablation Does Not Increase Treatment Effect in Hepatocellular Carcinoma

BACKGROUND

Preclinical studies have shown that modulation of the tumor microvasculature with anti-angiogenic agents decreases tumor perfusion and may increase the efficacy of radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC). Retrospective studies suggest that sorafenib given prior to RFA promotes an increase in the ablation zone, but prospective randomized data are lacking.

AIMS

We conducted a randomized, double-blind, placebo-controlled phase II trial to evaluate the efficacy of a short-course of sorafenib prior to RFA for HCC tumors sized 3.5-7 cm (NCT00813293).

METHODS

Treatment consisted of sorafenib 400 mg twice daily for 10 days or matching placebo, followed by RFA on day 10. The primary objectives were to assess if priming with sorafenib increased the volume and diameter of the RFA coagulation zone and to evaluate its impact on RFA thermal parameters. Secondary objectives included feasibility, safety and to explore the relationship between tumor blood flow on MRI and RFA effectiveness.

RESULTS

Twenty patients were randomized 1:1. Priming with sorafenib did not increase the size of ablation zone achieved with RFA and did not promote significant changes in thermal parameters, although it significantly decreased blood perfusion to the tumor by 27.9% (p = 0.01) as analyzed by DCE-MRI. No subject discontinued treatment owing to adverse events and no grade 4 toxicity was observed.

CONCLUSION

Priming of sorafenib did not enhance the effect of RFA in intermediate sized HCC. Future studies should investigate whether longer duration of treatment or a different antiangiogenic strategy in the post-procedure setting would be more effective in impairing tumor perfusion and increasing RFA efficacy.

A quantitative analysis of escalating antineoplastic medication price increases

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Background: Established antineoplastic medication prices are overall increasing, yet the yearly trend and additive cost of such increases relative to overall antineoplastic spending is often unclear. Methods: We accessed the yearly reimbursement files from Medicare Part B for parenteral antineoplastic agents (codes J8501-J9999) for the years 2010-2020 and adjusted all values to 2020 USD to account for inflation. We calculated an initial inflation-adjusted price-per-claim for every medication at the time of medication entry to the database and compared that price with the yearly price-per-claim that Medicare reimbursed. For medications whose price had increased beyond the initial inflation-adjusted price, we multiplied the annual differences with the total annual claims of the medication reimbursed in order to calculate the additional cost accrued by Medicare for every affected year. We only included medications with total annual cost >10 million USD/yr in our analysis. Results: Price increases were noted in 70.9% of already established medications annually (median 74.5%, range 52.17-81.48%). This led to an average additional extra cost of 311 million USD (range 156-492 million USD) annually, for a total of 3.1 billion USD over the 10 years of observation. This extra cost represented 4.6-9.3% of the total Medicare Part B spending for antineoplastic medications annually and this percentage rose yearly by a statistically significant 0.43% (95% CI 0.14%-0.73%, P = 0.01; R2 0.59) in absolute terms (Table). Rituximab (1,003 million USD), trastuzumab (421 million USD), and bevacizumab (326 million USD) accumulated the highest extra costs. Conclusions: The majority of established parenteral antineoplastics are affected by escalating price increases beyond the rate of inflation. Year-by-year, these increases occupy a progressively larger part of overall Medicare Part B spending. Since Medicare does not negotiate medication price nor receives rebates but rather relies on average market prices, these increases likely affect other U.S. markets as well.[Table: see text]

Large scale proteomics of circulating extracellular vesicles to reveal novel biomarkers for pancreatic cancer

523

Background: Robust biomarkers are urgently needed to assist in diagnosing pancreatic cancer. Earlier cancer diagnosis could increase survival rates by an estimated 5-fold and more reliable and real-time assessment of treatment effects in patients with cancer could improve quality of life and reduce healthcare costs. Isolation of circulating extracellular vesicles (cEVs) as ‘liquid biopsies’ offers an advantageous approach to diagnose and monitor disease status. Methods: We conducted a comprehensive proteomics study of cEVs from plasma samples to identify EV proteins that may be used as biomarkers for the diagnosis and prognosis of pancreatic cancer. Patients with pancreatic ductal adenocarcinoma (PDAC) of various tumor stages, chronic pancreatitis, intraductal papillary mucinous neoplasm (IPMN), and age-matched controls were enrolled. EVs were isolated directly from plasma samples using the affinity-based EVTrap method then subject to quantitation by liquid chromatography-tandem mass spectrometry. Results: A total of 124 patients (93 with PDAC, 12 with chronic pancreatitis, 8 with IPMN and 11 controls) were included in the discovery cohort. The isolation of EVs with EVtrap allowed the identification on average of 912 EV proteins per 100µL of sample. Principal component analysis of the cEV proteome showed clear separation between PDAC and benign pancreatic diseases. Individuals with IPMN were more closely related to controls, whereas chronic pancreatitis cases were more related to PDAC. At the functional level, we noted that cytokeratin, protein folding chaperons, and actin dynamics regulators were among protein clusters more highly altered in the cEV of patients with PDAC. We further identified new cEV markers associated with metastatic disease, such as PSMB4, RUVBL2, and ANKAR, as well as other EV proteins with strong correlation to prognosis, such as CRP, RALB, and CD55. Finally, we validated a 7-protein PDACEV signature in a validation cohort of 36 separate patients (24 with PDAC, 6 with chronic pancreatitis and 6 with IPMN) which yielded an 89% prediction accuracy for the diagnosis of PDAC. Conclusions: This study provides a valuable resource to the scientific community with a comprehensive catalog of novel proteins on circulating EVs that may assist in the development of novel biomarkers and improve the outcomes of patients with pancreatic cancer.

Organoid Sensitivity Correlates with Therapeutic Response in Patients with Pancreatic Cancer

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) remains a significant health issue. For most patients there are no options for targeted therapy and existing treatments are limited by toxicity. The HOPE trial (Harnessing Organoids for PErsonalized Therapy) was a pilot feasibility trial aiming to prospectively generate patient derived organoids (PDOs) from patients with PDAC and test their drug sensitivity and correlation with clinical outcomes.

EXPERIMENTAL DESIGN

PDOs were established from a heterogeneous population of patients with PDAC including both basal and classical PDAC subtypes.

RESULTS

A method for classifying PDOs as sensitive or resistant to chemotherapy regimens was developed to predict the clinical outcome of study subjects. Drug sensitivity testing on PDOs correlated with clinical responses to treatment in individual patients.

CONCLUSION

These data support the investigation of PDOs to guide treatment in prospective interventional trials in PDAC.

CTIM-18. LUMINOS-101: INITIAL SAFETY AND TOLERABILITY OF PVSRIPO AND PEMBROLIZUMAB COMBINATION THERAPY IN RECURRENT GLIOBLASTOMA

BACKGROUND

Recurrent glioblastoma (rGBM) is rapidly fatal with current therapies. PVSRIPO is an intratumoral immunotherapy targeting CD155 on antigen-presenting and malignant cells of solid tumors. Preclinically, PVSRIPO treatment leads to systemic, tumor antigen-specific, polyfunctional T-cell–mediated anti-tumor response, predominately driven by type I/III interferons. This inflammatory signature generates anti-tumor immunity and upregulates the programmed death (PD)-1 immune checkpoint in the tumor microenvironment. Preclinical models (including GBM) have shown that PVSRIPO+anti-PD-1/L1 therapy was more efficacious than either agent alone, warranting further investigation.

METHODS

Adults with histologically confirmed rGBM (1-2 prior progressions), Karnofsky performance status (KPS) ≥70, and an active, supratentorial, contrast-enhancing lesion (1-5.5 cm), received PVSRIPO (5x107 TCID50) intratumorally via convection-enhanced delivery (Day 1), followed by 200 mg pembrolizumab IV at week 2, given every 3 weeks for up to 24 months, to evaluate the safety/efficacy of the combination. A safety lead-in period (n=3-6) with a minimum 21–28-day delay before treatment of subsequent patients was planned, with a data safety monitoring board (DSMB) evaluating safety/tolerability prior to expansion (up to N=30).

RESULTS

The first 3 patients enrolled (ages 55-60, KPS 90-100) all received PVSRIPO followed by pembrolizumab (1-5 cycles), as planned. At cutoff (26-106 days of follow-up), there were no dose-limiting toxicities, treatment-emergent (TE) serious adverse events (SAE), or TEAEs necessitating a delay in initial/subsequent pembrolizumab treatments. All patients experienced a related TEAE, all grade 1 or 2 in severity. One patient experienced an AE of special interest (peritumoral edema, resulting in headache and hemiparesis), successfully managed with low-dose bevacizumab and corticosteroids. The DSMB unanimously recommended the study proceed without modification.

CONCLUSIONS

Intratumoral PVSRIPO+pembrolizumab was reasonably well tolerated, warranting continued investigation of the safety and efficacy of this combination in patients with rGBM.

CTIM-06. CLINICAL EFFICACY AND BIOMARKER ASSESSMENT OF VT1021, A CD36/CD47 DUAL-TARGETING AGENT, IN RECURRENT GLIOBLASTOMA

Glioblastoma (GBM) is the most common and aggressive primary brain malignancy in adults and recurs after treatment in >90% of all patients. Prognosis of patients with recurrent GBM (rGBM) is poor with a median progression free survival of ~1.8 months and median overall survival of 8-10 months. VT1021, a cyclic peptide derived from prosaposin, induces the expression of thrombospondin-1 (TSP-1) in myeloid derived suppressor cells (MDSCs), which are heavily recruited to the tumor microenvironment. Following completion of the Phase 1 Dose Escalation study and determination of the RP2D, an expansion study was conducted in a heavily pretreated rGBM population. The results of the expansion study reveal that VT1021 is safe and well tolerated in rGBM. Pharmacodynamic response to VT1021 was observed by induction of TSP-1 in circulating MDSCs and in the tumor microenvironment. VT1021 demonstrated significant single agent activity. Among 22 evaluable GBM subjects, 3 had complete response (CR), 1 had partial response (PR), and 7 had stable disease (SD) with an average study duration of over 120 days. The overall disease control rate (DCR) was 50%. Among the 3 CR, 2 showed complete radiological regression of the target lesion, the third was found to have no evidence of disease upon pathological examination following surgery. Nine of the 19 (47%) evaluable subjects with available biopsy samples showed high expression levels of both CD36 AND CD47. Among these 9 subjects, 3 achieved CR, representing an overall response rate of 33.3%, with another 3 patients achieving SD for a DCR of 67%. In conclusion, VT1021 demonstrates promising single-agent clinical activity in rGBM, particularly in subjects with high expression levels of CD36 and CD47. Additional clinical studies have been planned to further investigate the efficacy of VT1021 in rGBM and other solid tumor indications.

479 AGEN1181, an Fc-enhanced anti-CTLA-4 antibody, alone and in combination with balstilimab (anti-PD-1) in patients with advanced solid tumors: Initial phase I results

Background

AGEN1181 is a novel anti-CTLA-4 antibody with enhanced FcyR-dependent functionality, engineered to bind high and low binding alleles of FcyRIIIA, promoting superior T cell priming, memory responses, and depletion of intratumoral T regulatory cells. Further, AGEN1181 avoids complement recruitment, predictive of better tolerability. Here we report initial safety and efficacy findings from a phase I/Ib study of AGEN1181 as monotherapy and in combination with balstilimab (BAL; anti-PD-1).

Methods

Eligible patients (pts) had advanced solid tumors refractory to standard therapies. AGEN1181 was dosed Q3W (0.1–3 mg/kg) or Q6W (1–2 mg/kg) as monotherapy, or Q6W (0.1–2 mg/kg) in combination with BAL Q2W (3 mg/kg).

Results

As of July 16th 2021, 102 pts received AGEN1181 (43 monotherapy, 59 combination). Median age, 63 years (29–83); 50.5% with ≥3 prior lines of therapy. MTD not yet reached with AGEN1181 dosing up to 3 mg/kg Q3W as monotherapy and 2 mg/kg in combination with BAL. The most common treatment-related adverse events (TRAEs) of any grade were fatigue (34.3%), diarrhea (32.4%), and nausea (19.6%) with grade ≥3 events in 21.6% (diarrhea/colitis, 11.8%, fatigue, 2.9%). Notably, no immune-related hypophysitis or pneumonitis has been observed. Discontinuation from AGEN1181 due to TRAEs occurred in 15% of pts. Grade 5 TRAEs occurred in two pts (colitis [chronic], intestinal perforation). The disease control rate in evaluable pts (completed ≥1 on-treatment scan) defined as best overall response of CR, PR, or SD ≥6 weeks was 48.1% for AGEN1181 monotherapy ≥1 mg/kg (1 CR, 3 PR, 9 SD) and 70% for combination (3 PR, 6 unconfirmed PR [uPR], 19 SD). Monotherapy responders include individual pts with MSS endometrial cancer (CR), PD-1-relapsed/refractory cervical cancer (PR), PD-1-relapsed/refractory melanoma (PR), and pancreatic cancer (PR). Enrollment is continuing in several disease expansion cohorts with combination therapy. For MSS CRC, 2 PR, 2 uPR, and 7 SD have been seen in 17 evaluable ≥1 mg/kg patients to date. In the ovarian cohort (n=6), 2 PRs and 3 SD are noted. Additional combination responders include one PR and uPR in MSS endometrial cancer, two uPRs in visceral angiosarcoma (uPRs) and one uPR in PD-1-relapsed/refractory NSCLC (uPR); the majority of the responses are recent and ongoing.

Conclusions

AGEN1181 alone and in combination with BAL demonstrates favorable tolerability and compelling clinical activity, notably in poorly immunogenic tumor types and PD-1-refractory pts. These results underscore the significant potential of AGEN1181 to expand benefit of anti-CTLA-4 therapy to a broader patient population.

Trial Registration

NCT03860272

Ethics Approval

The study obtained ethics approval at each participating center (UT Health Sciences Center at San Antonio, University of Colorado Cancer Center, St John’s Cancer Institute, and HonorHealth under WIRB Study number 1256391; USC Norris Comprehensive Cancer Center, Beth Israel Deaconess Medical Center, and MD Anderson Cancer Center, approval numbers HS19-00277, 19–132, and 140346, respectively). All patients provided written informed consent in accordance with federal, local, and institutional guidelines.

Motixafortide and Pembrolizumab Combined to Nanoliposomal Irinotecan, Fluorouracil, and Folinic Acid in Metastatic Pancreatic Cancer: The COMBAT/KEYNOTE-202 Trial

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is largely unresponsive to checkpoint inhibitors. Blockade of the CXCR4/CXCL12 axis increases intratumoral trafficking of activated T cells while restraining immunosuppressive elements. This study evaluates dual blockade of CXCR4 and PD1 with chemotherapy in PDAC.

PATIENTS AND METHODS

Multicenter, single-arm, phase II study to evaluate the safety and efficacy of motixafortide and pembrolizumab combined with chemotherapy in patients with de novo metastatic PDAC and disease progression on front-line gemcitabine-based therapy (NCT02826486). Subjects received a priming phase of motixafortide daily on days 1-5, followed by repeated cycles of motixafortide twice a week; pembrolizumab every 3 weeks; and nanoliposomal irinotecan, fluorouracil, and leucovorin every 2 weeks (NAPOLI-1 regimen). The primary objective was objective response rate (ORR). Secondary objectives included overall survival (OS), progression-free survival (PFS), disease control rate (DCR), safety, and tolerability.

RESULTS

A total of 43 patients were enrolled. The ORR according to RECISTv1.1 was 21.1% with confirmed ORR of 13.2%. The DCR was 63.2% with median duration of clinical benefit of 5.7 months. In the intention-to-treat population, median PFS was 3.8 months and median OS was 6.6 months. The triple combination was safe and well tolerated, with toxicity comparable with the NAPOLI-1 regimen. Notably, the incidence of grade 3 or higher neutropenia and infection was 7%, lower than expected for this chemotherapy regimen.

CONCLUSIONS

Triple combination of motixafortide, pembrolizumab, and chemotherapy was safe and well tolerated, and showed signs of efficacy in a population with poor prognosis and aggressive disease.

Abstract CT177: A multi-center phase 2a trial of the CXCR4 inhibitor motixafortide (BL-8040) (M) in combination with pembrolizumab (P) and chemotherapy (C), in patients with metastatic pancreatic adenocarcinoma (mPDAC)

Background: Improving outcomes of PDAC with checkpoint inhibitors (CPIs) have been ineffective, underscoring the need to co-target alternative pathways. Preclinical data showed that CXCR4-SDF1 axis modulates the tumor microenvironment (TME) in PDAC and that CXCR4 inhibition enhances T cell access to the TME, increasing tumor sensitivity to CPIs. This was confirmed in the COMBAT Cohort 1 (CC1) study showing that the dual combination M+P increases activated CD8+ T cells and decreases myeloid derived suppressor cells (MDSCs) within the TME. Moreover, our pre-clinical studies showed that adding C to M+P resulted in improved efficacy vs C alone. The COMBAT Cohort 2 (CC2) aims to test the safety and efficacy of the triple combination of M+P+C in 2L mPDAC. Methods: Single arm phase 2a study in mPDAC. In cohort 2, patients with stage IV PDAC at diagnose who had progressed to 1L gemcitabine-based C received 5 days M priming, followed by M BIW + P Q3W plus C [Irinotecan liposomal injection/5-FU/LV (OFL)] Q2W. The primary endpoint was RR. Results: A total of 43 patients with stage 4 PDAC, 98% of whom were diagnosed with stage 4 disease, were enrolled. Median age was 68 (40-85) and 74.4% had liver disease. The safety profile was consistent with the individual profiles of each treatment alone. Of note, the incidence of ≥G3 neutropenia (G3Neu) was 7% and ≥G3 infection was 7%, which is lower than expected for C (OFL) alone (20% and 17%, respectively). The levels of T-cells increased during M priming and returned to normal values, which remained stable across the study despite the OFL treatment. For the evaluable patients (N=38) the ORR was 21.1% with a 13.2% confirmed ORR (defined as two consecutive assessments showing PR) and a 63.2% DCR (PR+SD). Median duration of clinical benefit was 5.6 months. Median OS and PFS were 6.5 months and 4.0 months, respectively (6.6 months and 3.8 months, respectively, for the ITT population). Conclusions: The triple combination of M+P+C is tolerable and shows encouraging results with cORR 13.2%, mPFS 4.0 months and mOS 6.5 months (compared to 7.7%, ~3 months and 4.7 months, respectively, on a historical basis for OFL alone in the stage 4 diagnosis subpopulation). SD of 42.1% and DCR of 63.2% were also higher than historical data on SoC chemotherapy used in 2L patients. The incidence of severe neutropenia and infections is lower than the historical data on C. The results from the CC2 suggest that M+P may expand the efficacy and safety benefit of OFL in PDAC, and warrants further investigation in a randomized study.

Citation Format: Manuel Hidalgo, Teresa Macarulla, Valerya Semenisty, Erkut Borazanci, Jaime Feliu, Mariano Ponz-Sarvise, David Gutierrez Abad, Paul Oberstein, Angela Alistar, Andres Muñoz, Ravit Geva, Carmen Guillén-Ponce, Mercedes Salgado Fernandez, Amnon Peled, Marya Chaney, Irit Glicko-Kabir, Liron Shemesh-Darvish, Debby Ickowicz, Ella Sorani, Shaul E. Kadosh, Abi Vainstein-Haras, Bruno Bockorny. A multi-center phase 2a trial of the CXCR4 inhibitor motixafortide (BL-8040) (M) in combination with pembrolizumab (P) and chemotherapy (C), in patients with metastatic pancreatic adenocarcinoma (mPDAC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT177.

First-in-human phase 1 trial (DRAGON) of SRK-181, a potential first-in-class selective latent TGFβ1 inhibitor, alone or in combination with anti-PD-(L)1 treatment in patients with advanced solid tumors

TPS3146

Background: Transforming growth factor-beta 1 (TGFβ1) is a key mediator of primary resistance to programmed cell death protein 1 (PD-1) pathway blockade. SRK-181 is a fully human, highly potent and selective monoclonal antibody that inhibits latent TGFβ1 activation. SRK-181 has minimal or no binding to latent TGFβ2 and TGFβ3 isoforms or to active TGFβ growth factors. In mouse tumor models (bladder, melanoma, and breast cancer), SRK-181 in combination with anti-PD1 therapy overcame primary anti-PD-1 resistance and showed survival benefit. No cardiotoxicities (valvulopathy) were observed with SRK-181 in 4-week GLP nonclinical toxicology studies. Thus, the potency and selectivity of SRK-181 may overcome PD-1 inhibitor resistance and toxicity of non-selective TGFβ pathway approaches. Methods: The DRAGON trial NCT04291079 is an ongoing multicenter, open-label, phase 1 study of SRK-181 administered by IV infusion every 3 weeks (Q3W) alone or in combination with anti-PD-(L)1 in patients (pts) with locally advanced or metastatic solid tumors. The study comprises 3 parts: Part A of the study follows a standard 3+3 dose escalation trial design to evaluate safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and antitumor activity of SRK-181 alone (Part A1) or in combination with the anti-PD-(L)1 agent that is approved for the respective tumor indication (Part A2). Part A1 and Part A2 will determine maximum tolerated dose (MTD) or maximum administered dose and Recommended Phase 2 Dose (RP2D) for Part B. Part B (expansion phase) will evaluate combination treatment of SRK-181 with anti-PD-(L)1 in pts with non-small cell lung cancer, urothelial carcinoma (UC), melanoma or other advanced solid tumors, to confirm the tolerability of the RP2D and to evaluate the antitumor activity of combination treatment. Pts in Part A2 and Part B must have previously received an anti-PD-(L)1 therapy approved in their tumor indication and considered non-responders (best response of stable disease or disease progression) to anti-PD-(L)1 monotherapy. Pts in Part B must have received the most recent dose of the prior anti-PD-(L)1 within 6 months of study enrollment (9 months for UC cohort). Safety, PK, PD and efficacy data will be collected and monitored throughout the study. Detailed translational PD and predictive biomarker studies for SRK-181 will include a novel digital pathology analysis of CD8 to assess the alteration of immune profile in tumor microenvironment and TGFb pathway biomarkers, such as quantitative analysis of tumor phospho-Smad2 and circulating levels of TGFb1 ligand. As of Feb 01 2021, dose escalation has proceeded to the highest planned dose of 2400 mg Q3W in Part A1 (monotherapy) and to 800 mg Q3W in Part A2 (anti-PD-(L)1 combination). Additional planned doses in Part A2 are 1600 mg and 2400 mg Q3W. Clinical trial information: NCT04291079.

PDX-derived organoids model in vivo drug response and secrete biomarkers

Patient-derived organoid models are proving to be a powerful platform for both basic and translational studies. Here we conduct a methodical analysis of pancreatic ductal adenocarcinoma (PDAC) tumor organoid drug response in paired patient-derived xenograft (PDX) and PDX-derived organoid (PXO) models grown under WNT-free culture conditions. We report a specific relationship between area under the curve value of organoid drug dose response and in vivo tumor growth, irrespective of the drug treatment. In addition, we analyzed the glycome of PDX and PXO models and demonstrate that PXOs recapitulate the in vivo glycan landscape. In addition, we identify a core set of 57 N-glycans detected in all 10 models that represent 50%-94% of the relative abundance of all N-glycans detected in each of the models. Last, we developed a secreted biomarker discovery pipeline using media supernatant of organoid cultures and identified potentially new extracellular vesicle (EV) protein markers. We validated our findings using plasma samples from patients with PDAC, benign gastrointestinal diseases, and chronic pancreatitis and discovered that 4 EV proteins are potential circulating biomarkers for PDAC. Thus, we demonstrate the utility of organoid cultures to not only model in vivo drug responses but also serve as a powerful platform for discovering clinically actionable serologic biomarkers.

Abstract CT119: Organoid sensitivity in pancreatic cancer correlates with clinical response to treatment and reveals utility for reducing toxicity: Preliminary results from the HOPE trial

The HOPE trial (Harnessing Organoids for PErsonalized Therapy) was a pilot study to test the feasibility of generating patient derived organoids (PDOs) from patients with pancreatic cancer under real world conditions, test drug sensitivity against these PDOs, and correlate these findings with clinical outcomes. Biopsies were obtained primarily during routine clinical care from surgical specimens, ascites, fine needle biopsies (FNB) of primary tumors, and IR guided core biopsies of liver and lymph node metastases. PDOs were grown in WNT free media according to our previously published methods. PDO drug sensitivity testing was performed on a panel of drugs, AUC calculated, and sensitivity ranked. Patients were followed clinically and assessed for disease control. At data cutoff (January 2020), we enrolled a total of 76 subjects representing all stages of disease. Drug testing was performed successfully on PDOs generated from 12 of these subjects (16%). Factors contributing to success obtaining sufficient cells for PDO generation included modality, body part, and tumor cellularity. H&E and IHC corresponded in matched PDOs and donor tumors, as did DNA alterations. Transcriptomes of PDOs were classified as both ‘basal' and ‘classical' subtypes. When AUC values were annotated with clinical data, the Jenks break of 1.69 segregated matched PDO/AUC values into disease control and progressive disease. We estimated that a PDO AUC value <1.66 yields a > 99% probability of disease control from a regimen that contains this drug, whereas if all drugs in a regimen had an AUC > 2.75 there is a > 80% probability of accurately predicting resistance. To illustrate the potential of PDO testing to tailor treatment for an individual patient, we described a case of a subject with stage IV PDAC with a KRAS mutation and ERBB2 amplification. The subject had disease control with FOLFIRINOX, which was held for toxicity. The PDO showed resistance to oxaliplatin and the patient subsequently had an extended period of disease control with regimens which did not include oxaliplatin, highlighting the potential of PDO drug sensitivity testing to exclude ineffective treatments from combination chemotherapy and limit toxicity. In conclusion, we have shown the feasibility of collecting material via real-world clinical practice sufficient to develop PDOs suitable for rapidly screening multiple drugs, and have shown a high degree of correlation between clinical outcomes in patients with PDAC and matched PDO drug sensitivity. We determined preliminary criteria based on the AUC of individual drugs in PDOs to predict drug sensitivity in subjects. These results highlight the potential of PDOs to personalize therapy and allow for the exclusion of ineffective drugs from combination regimens thereby reducing toxicity. We anticipate this approach will be used in future trials to prospectively inform treatment selection for patients with PDAC.

Citation Format: Joseph Elan Grossman, Ling Huang, Lakshmi Muthuswamy, Sofia Perea, Dipikaa Akshinthala, Raul Gonzalez, Leo Tsai, Jonah Cohen, Mandeep Sawhney, Douglas Pleskow, Tyler M. Berzin, Bruno Bockorny, Andrea Bullock, Benjamin Schlechter, Mary Linton B. Peters, Catherine Conahan, Supraja Narasimhan, Christine Lim, Roger Davis, Robert Besaw, Martin Smith, Tara Kent, Mark Callery, Senthil K. Muthuswamy, Manuel Hidalgo. Organoid sensitivity in pancreatic cancer correlates with clinical response to treatment and reveals utility for reducing toxicity: Preliminary results from the HOPE trial [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT119.

Discovery of New Targets to Control Metastasis in Pancreatic Cancer by Single-cell Transcriptomics Analysis of Circulating Tumor Cells

Metastasis development is the leading cause of cancer-related mortality in pancreatic ductal adenocarcinoma (PDAC) and yet, few preclinical systems to recapitulate its full spreading process are available. Thus, modeling of tumor progression to metastasis is urgently needed. In this work, we describe the generation of highly metastatic PDAC patient-derived xenograft (PDX) mouse models and subsequent single-cell RNA-sequencing (RNA-seq) of circulating tumor cells (CTC), isolated by human HLA sorting, to identify altered signaling and metabolic pathways, as well as potential therapeutic targets. The mouse models developed liver and lung metastasis with a high reproducibility rate. Isolated CTCs were highly tumorigenic, had metastatic potential, and single-cell RNA-seq showed that their expression profiles clustered separately from those of their matched primary and metastatic tumors and were characterized by low expression of cell-cycle and extracellular matrix-associated genes. CTC transcriptomics identified survivin (BIRC5), a key regulator of mitosis and apoptosis, as one of the highest upregulated genes during metastatic spread. Pharmacologic inhibition of survivin with YM155 or survivin knockdown promoted cell death in organoid models as well as anoikis, suggesting that survivin facilitates cancer cell survival in circulation. Treatment of metastatic PDX models with YM155 alone and in combination with chemotherapy hindered the metastatic development resulting in improved survival. Metastatic PDX mouse model development allowed the identification of survivin as a promising therapeutic target to prevent the metastatic dissemination in PDAC.

BL-8040, a CXCR4 antagonist, in combination with pembrolizumab and chemotherapy for pancreatic cancer: the COMBAT trial

Programmed cell death 1 (PD-1) inhibitors have limited effect in pancreatic ductal adenocarcinoma (PDAC), underscoring the need to co-target alternative pathways. CXC chemokine receptor 4 (CXCR4) blockade promotes T cell tumor infiltration and is synergistic with anti-PD-1 therapy in PDAC mouse models. We conducted a phase IIa, open-label, two-cohort study to assess the safety, efficacy and immunobiological effects of the CXCR4 antagonist BL-8040 (motixafortide) with pembrolizumab and chemotherapy in metastatic PDAC (NCT02826486). The primary outcome was objective response rate (ORR). Secondary outcomes were overall survival (OS), disease control rate (DCR) and safety. In cohort 1, 37 patients with chemotherapy-resistant disease received BL-8040 and pembrolizumab. The DCR was 34.5% in the evaluable population (modified intention to treat, mITT; N = 29), including nine patients (31%) with stable disease and one patient (3.4%) with partial response. Median OS (mOS) was 3.3 months in the ITT population. Notably, in patients receiving study drugs as second-line therapy, the mOS was 7.5 months. BL-8040 increased CD8+ effector T cell tumor infiltration, decreased myeloid-derived suppressor cells (MDSCs) and further decreased circulating regulatory T cells. In cohort 2, 22 patients received BL-8040 and pembrolizumab with chemotherapy, with an ORR, DCR and median duration of response of 32%, 77% and 7.8 months, respectively. These data suggest that combined CXCR4 and PD-1 blockade may expand the benefit of chemotherapy in PDAC and warrants confirmation in subsequent randomized trials.

Dose-adjusted enoxaparin thromboprophylaxis in hospitalized cancer patients: a randomized, double-blinded multicenter phase 2 trial

Hospitalized patients with cancer are at an increased risk of developing venous thromboembolism (VTE). The recommendation for routine pharmacologic thromboprophylaxis in hospitalized patients with cancer to prevent VTE is based on extrapolation of results from noncancer cohorts. There are limited data to support the efficacy and safety of fixed-dose low-molecular-weight heparin (LMWH) regimens in high-risk hospitalized patients with cancer. We conducted a randomized, double-blinded, phase 2 trial in hospitalized patients with active cancer at high risk of developing VTE based on Padua risk score. Patients were randomly assigned to fixed-dose enoxaparin (40 mg daily) vs weight-adjusted enoxaparin (1 mg/kg daily) during hospitalization. The primary objectives were to evaluate the safety of dose-adjusted enoxaparin and evaluate the incidence of VTE with fixed-dose enoxaparin. Blinded clinical assessments were performed at day 14, and patients randomly assigned to fixed-dose enoxaparin subsequently underwent a bilateral lower extremity ultrasound. A total of 50 patients were enrolled and randomized. The median weight of patients enrolled in weight-adjusted enoxaparin arm was 76 kg (range, 60.9-124.5 kg). There were no major hemorrhages or symptomatic VTE in either arm. At time of completion of the blinded clinical assessment, there was only 1 incidentally identified pulmonary embolus that occurred in the weight-adjusted arm. In the group randomly assigned to fixed-dose enoxaparin who subsequently underwent surveillance ultrasound, the cumulative incidence of DVT was 22% (90% binomial confidence interval, 0%-51.3%). This phase 2 trial confirms a high incidence of asymptomatic VTE among high-risk hospitalized patients with cancer and that weight-adjusted LMWH thromboprophylaxis is feasible and well-tolerated. This trial was registered at www.clinicaltrials.gov as #NCT02706249.