Phase 1 dose-escalation study of SEA-CD40: a non-fucosylated CD40 agonist, in advanced solid tumors and lymphomas

BACKGROUND

SEA-CD40 is an investigational, non-fucosylated, humanized monoclonal IgG1 antibody that activates CD40, an immune-activating tumor necrosis factor receptor superfamily member. SEA-CD40 exhibits enhanced binding to activating FcγRIIIa, possibly enabling greater immune stimulation than other CD40 agonists. A first-in-human phase 1 trial was conducted to examine safety, pharmacokinetics, and pharmacodynamics of SEA-CD40 monotherapy in patients with advanced solid tumors and lymphoma.

METHODS

SEA-CD40 was administered intravenously to patients with solid tumors or lymphoma in 21-day cycles with standard 3+3 dose escalation at 0.6, 3, 10, 30, 45, and 60 µg/kg. An intensified dosing regimen was also studied. The primary objectives of the study were to evaluate the safety and tolerability and identify the maximum tolerated dose of SEA-CD40. Secondary objectives included evaluation of the pharmacokinetic parameters, antitherapeutic antibodies, pharmacodynamic effects and biomarker response, and antitumor activity.

RESULTS

A total of 67 patients received SEA-CD40 including 56 patients with solid tumors and 11 patients with lymphoma. A manageable safety profile was observed, with predominant adverse events of infusion/hypersensitivity reactions (IHRs) reported in 73% of patients. IHRs were primarily ≤grade 2 with an incidence associated with infusion rate. To mitigate IHRs, a standardized infusion approach was implemented with routine premedication and a slowed infusion rate. SEA-CD40 infusion resulted in potent immune activation, illustrated by dose dependent cytokine induction with associated activation and trafficking of innate and adaptive immune cells. Results suggested that doses of 10-30 µg/kg may result in optimal immune activation. SEA-CD40 monotherapy exhibited evidence of antitumor activity, with a partial response in a patient with basal cell carcinoma and a complete response in a patient with follicular lymphoma.

CONCLUSIONS

SEA-CD40 was tolerable as monotherapy and induced potent dose dependent immune cell activation and trafficking consistent with immune activation. Evidence of monotherapy antitumor activity was observed in patients with solid tumors and lymphoma. Further evaluation of SEA-CD40 is warranted, potentially as a component of a combination regimen.

TRIAL REGISTRATION NUMBER

NCT02376699.

Tucatinib plus trastuzumab for chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer (MOUNTAINEER): a multicentre, open-label, phase 2 study

BACKGROUND

HER2 is an actionable target in metastatic colorectal cancer. We assessed the activity of tucatinib plus trastuzumab in patients with chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer.

METHODS

MOUNTAINEER is a global, open-label, phase 2 study that enrolled patients aged 18 years and older with chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer at 34 sites (clinics and hospitals) in five countries (Belgium, France, Italy, Spain, and the USA). Initially, the study was designed as a single-cohort study, which was expanded following an interim analysis to include more patients. Initially, patients were given tucatinib (300 mg orally twice daily) plus intravenous trastuzumab (8 mg/kg as an initial loading dose, then 6 mg/kg every 21 days; cohort A) for the duration of treatment (until progression), and after expansion, patients were randomly assigned (4:3), using an interactive web response system and stratified by primary tumour location, to either tucatinib plus trastuzumab (cohort B) or tucatinib monotherapy (cohort C). The primary endpoint was confirmed objective response rate per blinded independent central review (BICR) for cohorts A and B combined and was assessed in patients in the full analysis set (ie, patients with HER2-positive disease who received at least one dose of study treatment). Safety was assessed in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT03043313, and is ongoing.

FINDINGS

Between Aug 8, 2017, and Sept 22, 2021, 117 patients were enrolled (45 in cohort A, 41 in cohort B, and 31 in cohort C), of whom 114 patients had locally assessed HER2-positive disease and received treatment (45 in cohort A, 39 in cohort B, and 30 in cohort C; full analysis set), and 116 patients received at least one dose of study treatment (45 in cohort A, 41 in cohort B, and 30 in cohort C; safety population). In the full analysis set, median age was 56·0 years (IQR 47-64), 66 (58%) were male, 48 (42%) were female, 88 (77%) were White, and six (5%) were Black or African American. As of data cutoff (March 28, 2022), in 84 patients from cohorts A and B in the full analysis set, the confirmed objective response rate per BICR was 38·1% (95% CI 27·7-49·3; three patients had a complete response and 29 had a partial response). In cohorts A and B, the most common adverse event was diarrhoea (55 [64%] of 86), the most common grade 3 or worse adverse event was hypertension (six [7%] of 86), and three (3%) patients had tucatinib-related serious adverse events (acute kidney injury, colitis, and fatigue). In cohort C, the most common adverse event was diarrhoea (ten [33%] of 30), the most common grade 3 or worse adverse events were increased alanine aminotransferase and aspartate aminotransferase (both two [7%]), and one (3%) patient had a tucatinib-related serious adverse event (overdose). No deaths were attributed to adverse events. All deaths in treated patients were due to disease progression.

INTERPRETATION

Tucatinib plus trastuzumab had clinically meaningful anti-tumour activity and favourable tolerability. This treatment is the first US Food and Drug Administration-approved anti-HER2 regimen for metastatic colorectal cancer and is an important new treatment option for chemotherapy-refractory HER2-positive metastatic colorectal cancer.

FUNDING

Seagen and Merck & Co.

Trial in progress: Natural killer (NK) cells with TGFβ receptor I inhibitor vactosertib and IL-2 in patients with metastatic colorectal cancer or hematologic malignancies

TPS273

Background: Natural killer (NK) cell therapy is emerging as a promising therapy for patients (pts) with solid tumors and hematologic malignancies with no reported toxicity associated with the cell therapy product itself. NK cell trials in solid tumors are limited by immune inhibitory tumor microenvironments that prevent trafficking and activity of donor NK cells, which is largely governed by TGFβ signaling. We recently developed a novel platform for ex vivo expansion of healthy donor NK cells. We previously showed these cells to be safe in a dose-escalation study when given without cytokine support, with early evidence of response in pts with metastatic colorectal cancer (CRC) and in pts with hematologic malignancies. IL-2 has been well-established as an important activating cytokine supporting NK cells in humans, but can also induce regulatory T cells, which further suppress NK cells by producing TGFβ. We seek to improve upon the early activity we previously observed with NK cells alone by administering concurrently with IL-2 and by limiting the inhibitory tumor microenvironment and regulatory T cells with TGFβ receptor 1 inhibitor vactosertib. Methods: This phase Ib open-label study evaluates the safety and persistence (primary objectives), and the clinical and biological activity and trafficking (secondary objectives) of our novel NK cell therapy in combination with IL-2 (aldesleukin) and TGFβ receptor 1 inhibitor vactosertib. Up to 12 pts with metastatic CRC or relapsed/refractory hematologic malignancies will be enrolled. Pts will undergo low-dose lymphodepletion with fludarabine and cyclophosphamide followed by 2 infusions of NK cells, administered 14 days apart. Concurrently, pts will receive aldesleukin subcutaneously 3 times weekly and vactosertib orally 5 consecutive days/week x4 weeks total. Pts will undergo pre- and post-treatment biopsies for quantification of NK cell trafficking and exploration of immune cell profiling changes in the tumor microenvironment. The trial is currently open to enrollment, with 1 pt accrued at time of submission. Clinical trial information: NCT05400122 .

Molecular characterization of metastatic colorectal cancer (mCRC) in patients (pts) treated with cetuximab and pembrolizumab

178

Background: Anti-EGFR therapy has the potential to increase a localized anti-tumor immune response. We recently published the results of a phase Ib/II trial of the anti-EGFR antibody cetuximab in combination with the anti-PD1 antibody pembrolizumab in pts with advanced, RASwt CRC (PMID: 34645646). Despite its partial local immunologic efficacy, this combination of cetuximab and pembrolizumab was inactive. Here we present the results of comprehensive molecular characterization of pts with tumors amenable to DNA and RNA sequencing. Methods: Forty-two pts with RASwt mCRC were treated with cetuximab plus pembrolizumab. Archival or fresh tumor samples were obtained at baseline and, in select patients, on-treatment. Tumor samples underwent targeted DNA sequencing and whole transcriptome sequencing. Gene set enrichment analysis (GSEA), metabolic dysregulation assessment, and immune deconvolution were performed. Genomic data were linked to clinical outcomes. Results: Eighteen pts had tissue available for dual DNA/RNA extraction and sequencing. Of these, 10 had available matched on-treatment tumor samples. The most common mutations detected in protein coding regions were TP53 (14 pts), ERBB4 (5 pts), CDKN2A and APC (6 pts each). There were no statistically significant differences in progression-free survival (PFS) in pts with and without resistance-associated mutations (i.e., RAS, MET, ERBB4). Further, there was no significant difference associated with the consensus molecular subtype (CMS). However, when we compared patients with stable/increased tumor change percentage to those with decreased tumor change percentage, we found downstream transcriptional differences associated with altered metabolism, and in particular lipid and amino acid metabolism. Conclusions: We identified a significant number of patients with mutations predicting resistance to either or both cetuximab and pembrolizumab; however, none were associated with survival. However, we did identify metabolic pathways of interest, which may be associated with response to therapy. It is important to note, our analysis is limited by the small number of specimens (Trial registration NCT02713373). Clinical trial information: NCT02713373 .

Updated results of a phase 1 study of SEA-CD40, gemcitabine, nab-paclitaxel, and pembrolizumab in patients with metastatic pancreatic ductal adenocarcinoma (PDAC; SGNS40-001)

708

Background: PDAC has a 5-year survival rate of <5% in patients with metastatic disease. Despite established frontline therapy with gemcitabine + nab-paclitaxel (GnP), outcomes remain poor and additional therapies are urgently needed. SEA-CD40 is a receptor-agonistic, nonfucosylated IgG1 antibody directed to CD40. SEA-CD40 binding to FcγRIIIa results in enhanced effector function and CD40 agonism, allowing amplification of immune stimulation and antitumor activity. In preliminary results of a phase 1 study, SEA-CD40 + GnP + pembrolizumab (pembro) showed a tolerable safety profile and evidence of immune activation in patients (pts) with PDAC. Here, we present updated clinical results for this cohort. Methods: Pts were ≥18 years old with untreated metastatic PDAC and ECOG Performance Status of 0 or 1. Gemcitabine (1000 mg/m2) and nab-paclitaxel (125 mg/m2) were given on days 1, 8, and 15 and SEA-CD40 (10 or 30 µg/kg) was given on day 3 of each 28-day cycle. Pembro (400 mg) was given every 6 weeks starting on day 8 for up to 2 years. Results: As of August 16, 2022, 61 pts were treated with 10 µg/kg (N=40) or 30 µg/kg (N=21) SEA-CD40. Median duration of exposure was 25.1 weeks. Confirmed objective responses were observed in 19 pts (48% [95% CI 31.5, 63.9]) at 10 µg/kg and 8 pts (38% [95% CI 18.1, 61.6]) at 30 µg/kg. Median duration of response (months) was 5.7 (95% CI 3.9, 7.4) and 5.7 (95% CI 2.3, 9.2) for the 10 and 30 µg/kg dose groups, respectively. Additional efficacy results are summarized. The most common treatment-emergent adverse events (TEAEs) across dose groups were fatigue (84%), nausea (74%), and neutropenia (67%). The most common grade ≥3 TEAEs across the groups were neutropenia (61%), anemia (33%), and thrombocytopenia (20%). TEAEs leading to treatment discontinuation were reported in 10% of pts, including immune-mediated lung disease (n=3) and septic shock (n=1) in the 10 µg/kg dose group, and colitis (n=1) and portal vein thrombosis (n=1) in the 30 µg/kg dose group. Conclusions: The combination of SEA-CD40 + GnP + pembro has an acceptable safety profile and shows evidence of antitumor activity in pts with PDAC. This regimen may warrant further evaluation. Clinical trial information: NCT02376699 . [Table: see text]

The efficacy and safety of neoadjuvant immunotherapy in patients with deficient mismatch repair/microsatellite instability–high (dMMR/MSI-H) localized and oligometastatic colon cancer: Data from the real world

105

Background: Patients with potentially resectable dMMR/MSI-H colon cancer (CC) often receive neoadjuvant immunotherapy (IO) if co-morbid conditions or the extent of disease preclude upfront surgery. We investigated the outcome of such patients treated in a real-world setting. Methods: This is a single-center retrospective study that included patients with dMMR/MSI-H localized and oligometastatic CC receiving neoadjuvant IO between January 1, 2016, and July 31, 2022 with a data cut-off date of September 15, 2022. Electronic charts were reviewed to gather data on patient characteristics, tumor characteristics, detailed treatment, toxicity, treatment response, and survival. The response was assessed by radiologic studies, endoscopy, pathology in resected patients, and circulating tumor DNA. Results: The study included 24 patients with a median age of 69 years (range, 32 to 91); 12 (50%) patients were female, and 5 (21%) patients were African American. Among the patients included, 12 (50%) had localized CC (9 of whom had clinical stage III disease), and the rest had oligometastatic CC. The reasons for not undergoing upfront surgery were co-morbidity in 12 patients (50%), disease extent in 11 (46%), and both in 1 (4%). Four patients (17%) received the ipilimumab/nivolumab combination, and the rest received pembrolizumab. Most patients (63%) received IO in the first-line setting. The median duration of IO and the time to best response were 7.5 months (range, 2 to 55) and 3 months (range, 3 to 12), respectively. Among 23 evaluable patients, the overall response rate (ORR) was 74 % (17/23), with complete response (CR) in 13 (57%), and partial response (PR) in 4 (17%) patients. Response assessment is pending in 1 patient. Four patients (17%) had stable disease (SD), and 2 patients (8 %) experienced progressive disease (PD) on IO (1 with localized and the other with metastatic CC). The median progression-free survival (PFS) and overall survival (OS) did not reach for the whole group after a median follow-up of 12.5 months (range, 2 to 69 months), with 19/24 (79 %) patients remaining progression-free. Three patients underwent surgery with 2/3 achieving pathological CR. Among the 12 patients with localized CC, ORR was 73% (6 CR, 2 PR, 2 SD, 1 PD, and 1 assessment pending); median PFS and OS were not reached after a median follow-up of 9 months (range, 2 to 45) with 1 patient experiencing progression on IO at the time of data cut-off. No unexpected toxicity was observed. Conclusions: In this small cohort of patients with dMMR/MSI-H localized and oligometastatic CC, most patients showed deep and durable responses to neoadjuvant IO, obviating the need for surgery. Progression on IO was rare. This real-world data support investigating a non-operative paradigm in patients with dMMR/MSI-H localized and oligometastatic CC.

Safety and Efficacy of Dostarlimab in Patients With Recurrent/Advanced Non-small Cell Lung Cancer: Results from Cohort E of the Phase I GARNET Trial

BACKGROUND

Dostarlimab is an anti-programmed cell death protein-1 antibody being evaluated in recurrent/advanced solid tumors, including non-small cell lung cancer (NSCLC), in the ongoing Phase I, multi-center, open-label, 2-part (dose escalation and cohort expansion) GARNET study (NCT02715284).

MATERIALS AND METHODS

Here, we report an interim analysis of patients with recurrent/advanced NSCLC who progressed following platinum-based chemotherapy. Patients received dostarlimab (500 mg IV every 3 weeks [Q3W] for Cycles 1-4, then 1000 mg Q6W) until disease progression or unacceptable toxicity for > 2 years. The primary endpoints were immune-related objective response rate (irORR) per investigator-assessed irRECIST and safety.

RESULTS

As of 8, July 2019, 67 patients with recurrent/advanced NSCLC were enrolled and treated with dostarlimab; the majority had programmed death ligand 1 (PD-L1) tumor proportion score (TPS) < 1% (35.8% of patients) or PD-L1 TPS 1%-49% (29.9% of patients); 7.5% had PD-L1 TPS ≥ 50%, and 26.9% had unknown PD-L1 TPS status. Median follow-up was 13.8 months (range: 0.0-22.6). irORR was 26.9%, including 2 complete and 16 partial responses. The median duration of response of 11.6 months (range: 2.8-19.4). Responses were observed in 2 of 24 (16.7%) patients with PD-L1 TPS < 1%, 4 of 20 (20.0%) patients with PD-L1 TPS 1%-49% and 2 of 5 (40.0%) patients with PD-L1 TPS ≥ 50%. Fatigue (4.5%) was the most common Grade ≥ 3 treatment-related treatment-emergent adverse event (TRAE). Immune-related TRAEs (any grade) were observed in 28.4% of patients.

CONCLUSION

Dostarlimab demonstrated promising antitumor activity in advanced/recurrent NSCLC that progressed following platinum-based chemotherapy, including across all PD-L1 subgroups, and has an acceptable safety profile.

Abstract CT246: Phase 1b/2 study of giloralimab in combination with modified FOLFIRINOX with or without budigalimab in patients with untreated metastatic pancreatic cancer

Background: The 5-year survival rate for metastatic pancreatic cancer is ~3%, indicating an urgent need for novel therapies. Combination therapy with modified FOLFIRINOX (leucovorin, irinotecan, 5-fluorouracil, and oxaliplatin) and immunotherapy has been proposed for first-line metastatic pancreatic cancer to improve tolerability and clinical efficacy, respectively (NCCN, Pancreatic. 2021; Vonderheide, Annu. Rev. Med. 2020). The present study evaluates the safety, pharmacokinetics, and preliminary antitumor activity of modified FOLFIRINOX + giloralimab (CD40 agonist) with or without budigalimab (anti-PD-1) in patients with untreated metastatic pancreatic cancer.

Methods: Multicenter, randomized phase 1b/2 study (NCT04807972) in patients (18-75 years) with untreated metastatic pancreatic cancer. The phase 1b (dose escalation) examines the safety dose level of giloralimab in a triplet of modified FOLFIRINOX + giloralimab + budigalimab using a Bayesian optimal interval [BOIN] design. BOIN design is utilized to guide giloralimab escalation decisions. In phase 2 (dose expansion), patients are randomized 1:1:1 to receive treatment with modified FOLFIRINOX (cohort A), modified FOLFIRINOX + giloralimab (cohort B), or modified FOLFIRINOX + giloralimab + budigalimab (cohort C). Randomization is stratified according to Eastern Cooperative Oncology Group performance status. Primary objectives are to assess the safety and tolerability of modified FOLFIRINOX + giloralimab + budigalimab (phase 1b) and to evaluate overall survival in patients treated with modified FOLFIRINOX + giloralimab with or without budigalimab (versus those receiving modified FOLFIRINOX alone; phase 2). Secondary objectives include characterizing the pharmacokinetics of giloralimab and budigalimab in combination with modified FOLFIRINOX, assessing the efficacy of modified FOLFIRINOX + giloralimab with or without budigalimab, and evaluating the safety/tolerability of modified FOLFIRINOX + giloralimab with or without budigalimab. Patients will receive giloralimab and budigalimab intravenously in combination with modified FOLFIRINOX in a 28-day cycle. Dose-limiting toxicities are assessed during the first cycle of dosing. Adverse events are evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events. Blood samples for pharmacokinetic analysis are collected at designated time points throughout the study. Responses are assessed by Response Evaluation Criteria in Solid Tumors version 1.1. Survival outcomes are described using the Kaplan-Meier method. Approximately 129 patients are planned to be included. Enrollment started in June 2021, with 7 patients enrolled as of November 2021.

Citation Format: Dung T. Le, Marcia Cruz-Correa, David L. Bajor, Rocio Garcia-Carbonero, Marion Harris, Roberto Pazo-Cid, Hedy Kindler, Nelson Yee, Suneel Kamath, Maulik Patel, Hua Fang, William Henner, Patrick Hardesty, Martha Blaney, Michael McDevitt, Talia Golan. Phase 1b/2 study of giloralimab in combination with modified FOLFIRINOX with or without budigalimab in patients with untreated metastatic pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT246.

Associations of Racial and Ethnic Category, Age, Comorbidities, and Socioeconomic Factors on Concordance to NCCN Guidelines for Patients With High-Risk Biliary Tract Cancers After Surgery

Background

Biliary tract cancers (BTC) have a limited prognosis even for localized cancers, emphasizing the importance of multidisciplinary management. NCCN guidelines recommend adjuvant chemotherapy (CT) +/- radiotherapy (RT) for high-risk disease. We analyzed the association between racial and ethnic category along with other demographic factors and concordance to NCCN guidelines among patients following surgery for high-risk BTC.

Methods

Subjects were identified from the National Cancer Database (NCDB) for BTC patients who underwent surgery and found to have metastatic lymph nodes (LN+) or positive surgical margins (M+) from 2004 to 2015. We defined concordance to NCCN guidelines as receiving surgery + CT +/- RT and non-concordance to the guidelines as surgery +/- RT. Descriptive studies and multivariate logistic regression analysis was performed.

Results

A total of 3,792 patients were identified with approximately half being female (55.4%) and between the ages of 50-69 (52.8%). Most were White (76.3%) followed by Black (10.6%), Hispanic (8.5%), and Asian (5.3%). The BTC included extrahepatic cholangiocarcinoma (CCA) (48.6%), gallbladder cancer (43.5%), and intrahepatic CCA (7.9%). Most patients had an M- resection (71.9%) but also had LN+ disease (88.0%). There were no significant differences between racial groups in disease presentation (histological grade, tumor stage) and surgical outcomes (LN+, M+, hospital readmission, and 90 day post-surgery mortality). Hispanic patients as compared to White patients were less likely to be insured (85.7% vs 96.3%, p<0.001) and less likely to be treated at an academic facility (42.1% vs 52.1%, p=0.008). Overall, almost one-third (29.7%) of patients received non-concordant NCCN guideline care with Hispanic patients having the highest proportion of non-concordance as compared to Whites patients (36.1% vs 28.7%, p=0.029). On multivariate analysis, Hispanic ethnicity (HR=1.51, 95% CI: 1.15-1.99) remained significantly associated with non-concordance to NCCN guidelines.

Conclusion

This study indicates that Hispanic patients with high-risk BTC are significantly less likely to receive NCCN-concordant treatment in comparison to White patients. More research is needed to confirm and understand the observed disparities and guide targeted interventions at the system-level.

Adding Base-Excision Repair Inhibitor TRC102 to Standard Pemetrexed-Platinum-Radiation in Patients with Advanced Nonsquamous Non-Small Cell Lung Cancer: Results of a Phase I Trial

PURPOSE

TRC102, a small-molecule base-excision repair inhibitor, potentiates the cytotoxicity of pemetrexed and reverses resistance by binding to chemotherapy-induced abasic sites in DNA. We conducted a phase I clinical trial combining pemetrexed and TRC102 with cisplatin-radiation in stage III nonsquamous non-small cell lung cancer (NS-NSCLC).

PATIENTS AND METHODS

Fifteen patients were enrolled from 2015 to 2019. The primary objective was to determine the dose-limiting toxicity and maximum tolerated dose of TRC102 in combination with pemetrexed, cisplatin, and radiotherapy. Secondary objectives were to assess toxicity, tumor response, and progression-free survival at 6 months. Based on our preclinical experiments, pemetrexed-TRC102 was given on day 1, and cisplatin/radiotherapy was initiated on day 3. This schedule was duplicated in the second cycle. After completion, two additional cycles of pemetrexed-cisplatin were given. Toxicities were assessed using NCI CTACAE versions 4/5.

RESULTS

The median age was 69 years (45-79) with the median follow-up of 25.7 months (range, 7.9-47.4). No dose-limiting toxicities and no grade 5 toxicity were seen. Hematologic and gastrointestinal toxicities were the most common side effects. No clinical radiation pneumonitis was seen. Of 15 evaluable patients, three had complete response (20%), and 12 had partial response (80%). The 6-month progression-free survival was 80%, and the 2-year overall survival was 83%.

CONCLUSIONS

Pemetrexed-TRC102 combined with cisplatin/radiotherapy in NS-NSCLC is safe and well tolerated. The recommended phase II dose is 200 mg TRC102 along with cisplatin-pemetrexed. No additional safety signal was seen beyond the expected CRT risks. A phase II trial, integrating post-CRT immunotherapy with this aggressive DNA-damaging regimen, is warranted.

Phase Ib/II Study of Cetuximab plus Pembrolizumab in Patients with Advanced RAS Wild-Type Colorectal Cancer

PURPOSE

We evaluated the antitumor efficacy of cetuximab in combination with pembrolizumab in patients with RAS wild-type (RASwt), metastatic colorectal adenocarcinoma (mCRC).

PATIENTS AND METHODS

In this phase Ib/II study, cetuximab was combined with pembrolizumab in patients with RASwt mCRC with ≥ one prior line of therapy for advanced disease. We analyzed baseline on-treatment tumor tissues for changes in the tumor microenvironment (TME), using flow cytometry and multispectral immunofluorescence.

RESULTS

Forty-four patients were evaluable for efficacy. The study was negative for the primary efficacy endpoint [overall response rate: 2.6%, 6-month progression-free survival (PFS): 31%; P = 0.52]. Median PFS was 4.1 months [95% confidence interval (CI): 3.9-5.5 months]. No increase in adverse effects was identified. We observed favorable immunomodulation with 47% increase in the number of intratumoral CTLs posttreatment (P = 0.035). These changes were more pronounced in patients with tumor shrinkage (P = 0.05). The TME was characterized by high numbers of TIM3⁺ and CTLA4⁺ cells; there were few activated OX40⁺ cells. PD-L1 expression was higher in pretreatment tumor cells from metastatic sites versus primary tumor samples (P < 0.05). Higher numbers of PD-L1⁺ tumor cells at baseline were associated with tumor shrinkage (P = 0.04). Analysis of immune populations in the blood demonstrated decreases in PD-1⁺ memory effector cells (P = 0.04) and granulocytic myeloid-derived suppressor cells (P = 0.03), with simultaneous increases in CD4⁺/CTLA4⁺ cells (P = 0.01).

CONCLUSIONS

The combination of cetuximab and pembrolizumab is inactive in patients with RASwt mCRC, despite its partial local immunologic efficacy. Further development of immuno-oncology combinations with enhanced efficacy and/or targeting additional or alternative immune checkpoints merits investigation.

Neoadjuvant Selicrelumab, an Agonist CD40 Antibody, Induces Changes in the Tumor Microenvironment in Patients with Resectable Pancreatic Cancer

PURPOSE

CD40 activation is a novel clinical opportunity for cancer immunotherapy. Despite numerous active clinical trials with agonistic CD40 monoclonal antibodies (mAb), biological effects and treatment-related modulation of the tumor microenvironment (TME) remain poorly understood.

PATIENTS AND METHODS

Here, we performed a neoadjuvant clinical trial of agonistic CD40 mAb (selicrelumab) administered intravenously with or without chemotherapy to 16 patients with resectable pancreatic ductal adenocarcinoma (PDAC) before surgery followed by adjuvant chemotherapy and CD40 mAb.

RESULTS

The toxicity profile was acceptable, and overall survival was 23.4 months (95% confidence interval, 18.0-28.8 months). Based on a novel multiplexed immunohistochemistry platform, we report evidence that neoadjuvant selicrelumab leads to major differences in the TME compared with resection specimens from treatment-naïve PDAC patients or patients given neoadjuvant chemotherapy/chemoradiotherapy only. For selicrelumab-treated tumors, 82% were T-cell enriched, compared with 37% of untreated tumors (P = 0.004) and 23% of chemotherapy/chemoradiation-treated tumors (P = 0.012). T cells in both the TME and circulation were more active and proliferative after selicrelumab. Tumor fibrosis was reduced, M2-like tumor-associated macrophages were fewer, and intratumoral dendritic cells were more mature. Inflammatory cytokines/sec CXCL10 and CCL22 increased systemically after selicrelumab.

CONCLUSIONS

This unparalleled examination of CD40 mAb therapeutic mechanisms in patients provides insights for design of subsequent clinical trials targeting CD40 in cancer.

Abstract CT005: T cell inflammation in the tumor microenvironment after agonist CD40 antibody: Clinical and translational results of a neoadjuvant clinical trial

Deploying CD40 activation to stimulate T cell responses upstream of immune checkpoint molecules is a novel clinical opportunity for cancer immunotherapy. Despite numerous active clinical trials with agonistic CD40 monoclonal antibodies (mAb), biological treatment effects especially treatment-related modulation of the tumor microenvironment (TME), remain poorly understood. Here, we performed a neoadjuvant clinical trial of agonistic CD40 mAb (selicrelumab) administered intravenously with or without chemotherapy (gemcitabine and nab-paclitaxel) to 16 resectable patients with pancreatic ductal adenocarcinoma (PDAC) prior to surgery followed by adjuvant chemotherapy and CD40 mAb. The toxicity profile was acceptable, including only grade 1 or 2 cytokine release syndrome and expected toxicities from chemotherapy. Disease-free survival was 13.8 months (95% CI 2.9 - 24.8 months) and median overall survival was 23.4 months (95% CI 18.0 - 28.8), with 8 patients alive at a median of 20.0 months after surgery (follow-up range 12.2 to 34.8 months). Neoadjuvant selicrelumab induced major pharmacodynamic differences in the TME, as revealed by a multiplex imaging platform auditing the immune ecosystem, compared to resection specimens from PDAC patient previously untreated or given neoadjuvant chemotherapy/chemoradiotherapy only. For tumors resected after selicrelumab, 82% (9/11) were T-cell enriched, compared to 37% (38/104) (p=0.004) of untreated tumors and 23% (93/13) of chemotherapy/chemoradiation-treated tumors (p=0.012). Moreover, for selicrelumab tumors, tumor-associated fibrosis was less, “M2” macrophages were fewer, dendritic cells were more mature, and T cells were activated and proliferative, compared to the non-selicrelumab groups. In the periphery, CD8+ and CD4+ T cells were more activated and proliferative, and serum inflammatory cytokines CXCL10 and CCL22 increased after treatment. This study provides proof-of-concept in patients that agonistic CD40 mAb alters the TME, enhances T-cell infiltration, and modulates systemic inflammatory responses. These findings inform design of next-generation CD40 clinical trials.

Citation Format: Katelyn T. Byrne, Courtney B. Betts, Rosemarie Mick, Shamilene Sivagnanam, David L. Bajor, Daniel A. Laheru, E. Gabriela Chiorean, Mark H. O'Hara, Shannon M. Liudahl, Craig Newcomb, Cécile Alanio, Ana P. Ferreira, Byung S. Park, Takuya Ohtani, Austin P. Huffman, Sara A. Väyrynen, Andressa Dias Costa, Judith C. Kaiser, Andreanne M. Lacroix, Colleen Redlinger, Martin Stern, Jonathan A. Nowak, E. John Wherry, Martin A. Cheever, Brian M. Wolpin, Emma E. Furth, Elizabeth M. Jaffee, Lisa M. Coussens, Robert H. Vonderheide. T cell inflammation in the tumor microenvironment after agonist CD40 antibody: Clinical and translational results of a neoadjuvant clinical trial [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 CT005.

A pilot study of a low glycemic load diet in patients with stage I-III colorectal cancer

Background

Consumption of a diet with high glycemic indices has been associated with inferior cancer-specific outcomes in patients with early-stage colorectal cancer, but there is limited prospective evidence that alterations in dietary habits improves cancer outcomes. This study aimed to determine the feasibility and acceptability of following a low glycemic load (GL) diet in patients with stage I-III colorectal cancer.

Methods

Patients with stage I-III colorectal cancer, who completed definitive therapy, and consumed an average daily GL >150 participated in a 12-week tailored face-to-face dietary intervention with a target GL. This study followed a 2-stage design, with 4 planned cohorts, each with an assigned GL target and dietary intervention intensity. The primary endpoint of feasibility was determined by participant compliance, defined as an individual following the assigned GL ≥75% of the time. Compliance was determined using 24-hour telephone recalls. A cohort was deemed feasible if at least 67% of participants were compliant. Secondary endpoints included acceptability of the diet, nutritional support resources necessary to follow the diet, and evaluation of the effect of the diet on physical measures and correlative laboratories.

Results

Only cohort 1 was required as the primary endpoint of feasibility was met (stringent GL target, low intensity dietary support). The majority of participants experienced a decrease in body mass index (BMI) and waist circumference, 29% experiencing meaningful weight loss (≥5%). The dietitian spent an average of 6.97 hours (SD 2.18) face-to-face time and 1.58 hours (SD 0.68) by phone with each participant. Significant decreases were seen in total cholesterol, very-low-density lipoprotein (VLDL) and triglycerides (all P<0.05). All participants liked the foods and were satisfied with the diet. All participants felt the in-person meetings were helpful, and 62% did not feel a virtual meeting (e.g., Skype, etc.) could replace in-person meetings.

Conclusions

Patients with stage I-III colorectal cancer can follow a low GL diet with a 12-week in-person dietary intervention. Significant changes in physical and laboratory measures suggest relevant biologic effects of the dietary intervention. This study establishes feasibility, and warrants a larger scale prospective intervention trial to evaluate the impact of a low GL diet on cancer outcomes.

Adoption of single agent anticancer therapy for advanced hepatocellular carcinoma and impact of facility type, insurance status, and income on survival: Analysis of the national cancer database 2004-2014

Background

This study analyzes the pattern of use of single agent anticancer therapy (SAACT) in the treatment and survival of advanced hepatocellular carcinoma (aHCC) before and after sorafenib was FDA approved in 2007.

Methods

Adult patients diagnosed with HCC and treated with only ACT from 2004 – 2014 were identified in NCDB database. Patients were analyzed during three time frames: 2004–2006 (pre‐sorafenib (PS)), 2007–2010 (early sorafenib (ES)) and 2011–2014 (late sorafenib (LS)). Cox proportional hazards models and Kaplan‐Meier method were used for analyses.

Results

The NCDB contained 31,107 patients with HCC diagnosed from 2004–2014 and treated with ACT alone. Patients were generally men (78.0%), >50 years of age (92.5%). A significant increase in the rate of adaption of SAACT was observed over time: 6.2% PS, 15.2% ES, and 22.2% LS (p < 0.0001). During this later period, the highest proportion of SAACT is among academic and integrated network facilities (23.3%) as compared to community facilities (17.0%, p < 0.0001). The median overall survival of patients with aHCC treated only with SAACT improved significantly over time from 8.0 months (m) (95% CI: 7.4–8.8) to 10.7 m (10.4–11.2) to 15.6 m (15.2–16.0, p < 0.001). Multivariate analysis indicates worse outcomes for patients treated at community cancer programs (HR 1.28, (5% CI: 1.23–1.32), patients without insurance (HR 1.11, 1.06–1.16) and estimated household income of <$63,000 (HR 1.09, 1.05–1.13).

Conclusion

aHCC patients treated only with ACT have experienced an overall improvement in survival, but significant differences exist between facility type, insurance status, and income.

Videoconference Intervention for Distance Caregivers of Patients With Cancer: A Randomized Controlled Trial

PURPOSE

Approximately 20% of caregivers (CGs) live > 1 hour away from the patient and are considered distance caregivers (DCGs) who often report higher distress and anxiety than local CGs. The purpose of this study was to test the effectiveness of an intervention aimed at reducing anxiety and distress in DCGs of patients with cancer.

METHODS

This randomized controlled trial enrolled DCGs of patients with all cancer types who were being seen monthly by oncologists in outpatient clinics. There were three arms of the intervention delivered over a 4-month period: arm 1 (a) received 4 monthly videoconference-tailored coaching sessions with an advanced practice nurse or social worker focused on information and support, (b) participated in patient's appointments with the oncologist via videoconference over the 4-month study period, and (c) had access to a website designed for DCGs. Arm 2 did not receive the coaching sessions but received the other two components, and arm 3 received access to the DCG website only.

RESULTS

There were 302 DCGs who provided pre- and postintervention data. There were significant anxiety by group (P = .028 and r = 0.16) and distress by group interactions (P = .014 and r = 0.17). Arm 1 had the greatest percentage of DCGs who demonstrated improvement in anxiety (18.6%) and distress (25.2%).

CONCLUSION

Coaching and use of videoconference technology (to join the DCG into the patient-oncologist office visit) were effective in reducing both anxiety and distress for DCGs. These components could be considered for local CGs who-with COVID-19-are unable to accompany the patient to oncologist visits.

A comprehensive analysis of clinical trials in pancreatic cancer: what is coming down the pike?

OBJECTIVE

Pancreatic cancer is the most aggressive common cancer and is desperately in need of novel therapies. Unlike many other common cancers, there have been no new paradigm-changing therapies in the past 40 years beyond multi-agent chemotherapy. In this study, we perform the first comprehensive analysis of the current clinical trial landscape in pancreatic cancer to better understand the pipeline of new therapies.

MATERIALS AND METHODS

We queried https://clinicaltrials.gov/ for registered pancreatic cancer clinical trials. Studies were curated and categorized according to phase of study, clinical stage of the study population, type of the intervention under investigation, and biologic mechanism targeted by the therapy under study.

RESULTS

As of May 18, 2019, there were 430 total active therapeutic interventional trials testing 590 interventions. The vast minority of trials (n = 37, 8.6%) are in phase III testing. 189 (31%) interventions are immunotherapies, 69 (11%) target cell signaling pathways, 154 (26%) target cell cycle or DNA biology, and 35 (6%) target metabolic pathways. Of the late phase trials, only 14 are currently testing novel interventions. Rather, 23 phase III trials examine new ways to deliver existing FDA-approved drugs, procedures, or pain management.

CONCLUSIONS

A large number of novel therapeutic strategies are currently under investigation. They include a broad range of therapies targeting diverse biologic processes. However, only a small number of novel therapies are in late-stage testing, suggesting that future progress is likely several years away, and dependent on the success of early-stage trials.

5-Fluorouracil Enhances the Antitumor Activity of the Glutaminase Inhibitor CB-839 against PIK3CA-Mutant Colorectal Cancers

PIK3CA encodes the p110α catalytic subunit of PI3K and is frequently mutated in human cancers, including ∼30% of colorectal cancer. Oncogenic mutations in PIK3CA render colorectal cancers more dependent on glutamine. Here we report that the glutaminase inhibitor CB-839 preferentially inhibits xenograft growth of PIK3CA-mutant, but not wild-type (WT), colorectal cancers. Moreover, the combination of CB-839 and 5-fluorouracil (5-FU) induces PIK3CA-mutant tumor regression in xenograft models. CB-839 treatment increased reactive oxygen species and caused nuclear translocation of Nrf2, which in turn upregulated mRNA expression of uridine phosphorylase 1 (UPP1). UPP1 facilitated the conversion of 5-FU to its active compound, thereby enhancing the inhibition of thymidylate synthase. Consistently, knockout of UPP1 abrogated the tumor inhibitory effect of combined CB-839 and 5-FU administration. A phase I clinical trial showed that the combination of CB-839 and capecitabine, a prodrug of 5-FU, was well tolerated at biologically-active doses. Although not designed to test efficacy, an exploratory analysis of the phase I data showed a trend that PIK3CA-mutant patients with colorectal cancer might derive greater benefit from this treatment strategy as compared with PIK3CA WT patients with colorectal cancer. These results effectively demonstrate that targeting glutamine metabolism may be an effective approach for treating patients with PIK3CA-mutant colorectal cancers and warrants further clinical evaluation. SIGNIFICANCE: Preclinical and clinical trial data suggest that the combination of CB-839 with capecitabine could serve as an effective treatment for PIK3CA-mutant colorectal cancers.

Abstract 5535: SEA-CD40 is a non-fucosylated anti-CD40 antibody with potent pharmacodynamic activity in preclinical models and patients with advanced solid tumors

CD40 is a co-stimulatory receptor of the TNF receptor superfamily expressed on antigen presenting cells (APCs). Antibodies targeting CD40 may have therapeutic benefit via multiple mechanisms including innate immune activation that can support generation of antigen-specific, antitumor T cell responses, and binding to CD40-expressing cancer cells leading to antibody-mediated target cell killing. Multiple CD40-directed antibodies are in clinical development and differ by immunoglobulin isotype, affinity to CD40, and selectivity for FcγR-binding. These alterations could lead to differences in pharmacodynamic and antitumor activity.

SEA-CD40 is an agonistic non-fucosylated, humanized IgG1 monoclonal antibody directed against CD40. SEA-CD40 has enhanced FcγRIIIa binding (~10x greater than parent IgG1 antibody) that drives increased effector function, resulting in more potent immune stimulatory activity than antibodies with muted or selective FcγR binding. The enhanced effector function of SEA-CD40 may confer greater immune stimulation and antitumor activity relative to other CD40-directed therapeutics.

Preclinically, SEA-CD40 exposure results in a distinct signature of responses including activation of APCs, CD8+ and CD4+ T cells and NK cells, and targeted depletion of CD40+ B cells. SEA-CD40 demonstrates superior activity compared to other CD40-targeted antibodies in vitro and in vivo, suggesting that the enhanced effector function is critical for optimal immune cell agonism. For example, SEA-CD40 drove in vitro ADCC activity 100-fold above the parent antibody and exhibited robust ADCC with the low and high affinity FcγRIIIA genotype. At matched dose levels in cynomolgus monkeys, SEA-CD40 induced circulating cytokines and sustained B cell depletion that were up to 50-fold above that induced with the parent antibody. The SEA-CD40 signature of activation translates to increased antitumor activity as a single agent and in combination with standard of care treatments in preclinical models, suggesting the potential for beneficial combination therapy in the clinic.

The SEA-CD40 immune signature was confirmed by pharmacodynamic changes in an ongoing phase 1 clinical trial in patients with relapsed/refractory metastatic solid tumors (NCT02376699). SEA-CD40 treatment induced dose-dependent increases in circulating cytokines and chemokines associated with myeloid and lymphoid immune activation and trafficking. SEA-CD40 treatment also resulted in activation of CD4+ and CD8+ T cells and CD40-targeted B cell depletion in the periphery. These findings support continued clinical evaluation of SEA-CD40. The ongoing phase 1 clinical trial is actively enrolling and includes a cohort in pancreatic cancer assessing the combination of SEA-CD40, gemcitabine, nab-paclitaxel, and pembrolizumab.

Citation Format: Haley Neff-LaFord, Juneko E. Grilley-Olson, David C. Smith, Brendan Curti, Sanjay Goel, Timothy M. Kuzel, Svetomir N. Markovic, Olivier Rixe, David L. Bajor, Thomas F. Gajewski, Martin Gutierrez, Elisabeth I. Heath, John Thompson, Sahar Ansari, Shyra Gardai, Celine Jacquemont, Michael Schmitt, Andrew L. Coveler. SEA-CD40 is a non-fucosylated anti-CD40 antibody with potent pharmacodynamic activity in preclinical models and patients with advanced solid tumors [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 5535.

A facile and sensitive method of quantifying glutaminase binding to its inhibitor CB-839 in tissues

Many cancer types reprogram their metabolism to become addicted to glutamine. One of the critical enzymes in the utilization of glutamine in these cells is glutaminase. CB-839 (telaglenastat) is a drug that targets glutaminase that is currently being evaluated in many clinical trials for efficacy in various cancer types that are known to be driven by glutamine metabolism. Despite its use, there are limited assays available for testing the pharmacodynamic on-target effects of CB-839 on the limited, small-volume patient samples that are obtained in early-phase clinical trials. Thus, we developed an assay based on the cellular thermal shift assay technique using AlphaLISA technology to show that CB-839 specifically engages glutaminase in colon cancer cell lines in vitro and in minute quantities of mouse xenograft tumors. Notably, we show that this assay detects CB-839 binding to glutaminase in platelets of patients collected while receiving CB-839 on a clinical trial. This assay may be used to study the pharmacodynamic profile of CB-839 in very small tissue samples obtained from patients on a clinical trial and may be useful in future studies designed to screen other inhibitors of glutaminase.

Long-term outcomes of a phase I study of agonist CD40 antibody and CTLA-4 blockade in patients with metastatic melanoma

We report long-term clinical outcomes and immune responses observed from a phase 1 trial of agonist CD40 monoclonal antibody (mAb) and blocking CTLA-4 mAb in patients with metastatic melanoma. Twenty-four patients previously untreated with checkpoint blockade were enrolled. The agonistic CD40 mAb CP-870,893 and the CTLA-4 blocking mAb tremelimumab were dosed concomitantly every 3 weeks and 12 weeks, respectively, across four dose combinations. Two patients developed dose-limiting grade 3 immune-mediated colitis that led to the definition of the maximum tolerated dose (MTD). Other immune-mediated toxicity included uveitis (n = 1), hypophysitis (n = 1), hypothyroidism (n = 2), and grade 3 cytokine release syndrome (CRS) (n = 1). The estimated MTD was 0.2 mg/kg of CP-870,893 and 10 mg/kg of tremelimumab. In 22 evaluable patients, the objective response rate (ORR) was 27.3%: two patients (9.1%) had complete responses (CR) and four (18.2%) patients had partial responses (PR). With a median follow-up of 45 months, the median progression-free survival (PFS) was 3.2 months (95% CI, 1.3–5.1 months) and median overall survival (OS) was 23.6 months (95% CI, 11.7–35.5 months). Nine patients are long-term survivors (> 3 years), 8 of whom subsequently received other therapy including PD-1 mAb, surgery, or radiation therapy. Elevated baseline soluble CD25 was associated with shorter OS. Immunologically, treatment was associated with evidence of T cell activation and increased tumor T cell infiltration that was accomplished without therapeutic PD-1/PD-L1 blockade. These results suggest opportunities for immune activation and cancer immunotherapy beyond PD-1.

Metastatic progression is associated with dynamic changes in the local microenvironment

Most cancer-associated deaths result from metastasis. However, it remains unknown whether the size, microenvironment or other features of a metastatic lesion dictate its behaviour or determine the efficacy of chemotherapy in the adjuvant (micrometastatic) setting. Here we delineate the natural history of metastasis in an autochthonous model of pancreatic ductal adenocarcinoma (PDAC), using lineage tracing to examine the evolution of disseminated cancer cells and their associated microenvironment. With increasing size, lesions shift from mesenchymal to epithelial histology, become hypovascular and accumulate a desmoplastic stroma, ultimately recapitulating the primary tumours from which they arose. Moreover, treatment with gemcitabine and nab-paclitaxel significantly reduces the overall number of metastases by inducing cell death in lesions of all sizes, challenging the paradigm that PDAC stroma imposes a critical barrier to drug delivery. These results illuminate the cellular dynamics of metastatic progression and suggest that adjuvant chemotherapy affords a survival benefit by directly targeting micrometastases.

Lack of immunoediting in murine pancreatic cancer reversed with neoantigen

In carcinogen-driven cancers, a high mutational burden results in neoepitopes that can be recognized immunologically. Such carcinogen-induced tumors may evade this immune response through "immunoediting," whereby tumors adapt to immune pressure and escape T cell-mediated killing. Many tumors lack a high neoepitope burden, and it remains unclear whether immunoediting occurs in such cases. Here, we evaluated T cell immunity in an autochthonous mouse model of pancreatic cancer and found a low mutational burden, absence of predicted neoepitopes derived from tumor mutations, and resistance to checkpoint immunotherapy. Spontaneous tumor progression was identical in the presence or absence of T cells. Moreover, tumors arising in T cell-depleted mice grew unchecked in immune-competent hosts. However, introduction of the neoantigen ovalbumin (OVA) led to tumor rejection and T cell memory, but this did not occur in OVA immune-tolerant mice. Thus, immunoediting does not occur in this mouse model - a likely consequence, not a cause, of absent neoepitopes. Because many human tumors also have a low missense mutational load and minimal neoepitope burden, our findings have clinical implications for the design of immunotherapy for patients with such tumors.

CSF-1R-Dependent Lethal Hepatotoxicity When Agonistic CD40 Antibody Is Given before but Not after Chemotherapy

Cancer immunotherapies are increasingly effective in the clinic, especially immune checkpoint blockade delivered to patients who have T cell-infiltrated tumors. Agonistic CD40 mAb promotes stromal degradation and, in combination with chemotherapy, drives T cell infiltration and de novo responses against tumors, rendering resistant tumors susceptible to current immunotherapies. Partnering anti-CD40 with different treatments is an attractive approach for the next phase of cancer immunotherapies, with a number of clinical trials using anti-CD40 combinations ongoing, but the optimal therapeutic regimens with anti-CD40 are not well understood. Pancreatic ductal adenocarcinoma (PDA) is classically resistant to immunotherapy and lacks baseline T cell infiltration. In this study, we used a tumor cell line derived from a genetically engineered mouse model of PDA to investigate alterations in the sequence of anti-CD40 and chemotherapy as an approach to enhance pharmacological delivery of chemotherapy. Unexpectedly, despite our previous studies showing anti-CD40 treatment after chemotherapy is safe in both mice and patients with PDA, we report in this article that anti-CD40 administration <3 d in advance of chemotherapy is lethal in more than half of treated C57BL/6 mice. Anti-CD40 treatment 2 or 3 d before chemotherapy resulted in significantly increased populations of both activated myeloid cells and macrophages and lethal hepatotoxicity. Liver damage was fully abrogated when macrophage activation was blocked using anti-CSF-1R mAb. These studies highlight the dual nature of CD40 in activating both macrophages and T cell responses, and the need for preclinical investigation of optimal anti-CD40 treatment regimens for safe design of clinical trials.

Abstract A38: Phase I study of combination immunotherapy with agonistic CD40 monoclonal antibody (mAb) CP-870,893 (αCD40) and anti-CTLA-4 antibody tremelimumab (treme) in patients with metastatic melanoma

Purpose: Combining therapeutic activation of immune cells and checkpoint inhibition may improve response rates and overall survival in patients with metastatic melanoma. CP-870,893 (αCD40) is an agonistic fully human IgG2 mAb targeting the immune stimulatory molecule CD40. Treme is a fully human IgG2 mAb targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA4), a negative co-stimulatory molecule found on T cells.

Methods: Patients with histologically confirmed metastatic melanoma, measurable disease by RECIST 1.0, and no history of autoimmune diseases or previous treatments targeting CD40 or CTLA-4 were enrolled on a single-arm open-label dose escalation phase 1 study. αCD40 and treme were dosed i.v. every 3 weeks and 12 weeks, respectively , for a potential total of 16 doses of αCD40 and 4 doses of treme. Dose escalation followed a 3 + 3 strategy with alternating increases of αCD40 (range 0.1-0.2 mg/kg) and treme (range 6-15 mg/kg) in each cohort. Patient outcomes were scored using the Common Terminology Criteria for Adverse Events v3.0. Flow cytometric analysis of baseline blood samples was compared to samples obtained at least 3 weeks after the last dose of αCD40 and treme. Results were compared by paired t test.

Results: Toxicity: Twenty-four patients were enrolled and treated at 4 different dose levels. Two patients were replaced per protocol due to rapid, symptomatic progression of disease; these patients were not evaluated for response but were included in toxicity analysis. Patients had received a median of 1 (range 0-5) prior treatments for metastatic disease prior to enrollment. Dose-limiting toxicities (DLT), considered to be likely due to treatment, were colitis (n=1) and hypophysitis (n=1) at 0.2mg/kg αCD40 and 15mg/kg treme and uveitis (n=1) at 0.2mg/kg αCD40 and 10mg/kg treme. Cytokine release syndrome (CRS), grade 1-2, occurring within 24 hours of CP administration, was the most common treatment-related toxicity occurring in 19 (79.2%) patients and typically involving chills and fever. CRS symptoms were controlled with standard supportive care in the chemotherapy infusion suite and with instructed use of antipyretics and antihistamines at home. All episodes of CRS resolved within 24 hours of αCD40 administration. The estimated maximum tolerated dose was 0.2 mg/kg of αCD40 and 10 mg/kg of treme. Outcomes: Overall objective response rate was 27.3% (best response): two patients (9.1%) had complete responses to treatment and four (18.2%) patients had partial responses. The median follow-up was 22 months with a median progression free survival of 2.5 months (95% CI: 2.0–3.1 months) and a median overall survival (OS) of 26.1 months (95% CI: 13.1–39.1 months). Two patients remain disease free for more than 18 months after study completion without further medical treatment. Correlative studies: Flow cytometric analysis of peripheral blood lymphocytes revealed changes in CD8+ T cell phenotypes. Double positive granzyme B+ and Ki-67+ cells increased from 0.56 ± 0.17% (mean ± standard error) for all CD8+ T cells at baseline to 1.01 ± 0.23% post-treatment (p=0.03). CD8+ T cells expressing both programmed cell death 1 and eomesodermin were also higher after treatment, increasing from 7.7 ± 1.1% to 10.4 ±1.8% (p= 0.04) of all CD8+ T cells.

Conclusion: Combination therapy with αCD40 and treme was well-tolerated in patients with metastatic melanoma, with rates of CRS and other toxicity similar to previously reported rates for αCD40 or treme treatments alone. Overall objective response rate was 27.3%, with median OS of 26.1 months including two patients still disease-free. This antitumor activity, and biomarker evidence of immune activation, provides a rationale for expanded study.

Citation Format: David L. Bajor, Rosemarie Mick, Matthew J. Riese, Richman P. Lee, Xiaowei Xu, Drew A. Torigian, Erietta Stelekati, Martha Sweeney, Brendan J. Sullivan, Lynn M. Schuchter, Ravi Amaravadi, E John Wherry, Robert H. Vonderheide. Phase I study of combination immunotherapy with agonistic CD40 monoclonal antibody (mAb) CP-870,893 (αCD40) and anti-CTLA-4 antibody tremelimumab (treme) in patients with metastatic melanoma. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A38.

Abstract 5176: Chemotherapy alters the natural history of metastatic progression

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a 5-year survival rate of less than 6%. Metastatic disease accounts for a majority of PDAC-related deaths, even for patients with no evidence of metastasis at the time of resection. In this study we sought to understand the natural history of metastatic colonization and the cellular mechanisms governing the metastatic cascade. Using an autochthonous PDAC mouse model combined with a lineage-labeling approach, we have tracked and characterized the various stages of metastatic progression, from single cells to macroscopic lesions. PDAC tumors primarily metastasize to the liver, where small lesions of 10 cells or less reside closest to portal veins and exhibit a high frequency of epithelial-mesenchymal transition (EMT). Larger metastatic lesions exhibit reduced EMT and are hypovascular, resembling primary PDAC tumors. Metastases gradually accumulate desmoplasia as they grow, which consists of myofibroblasts, leukocytes and extracellular matrix components including collagen, hyaluronic acid, fibronectin and SPARC. Treatment with gemcitabine and nab-paclitaxel reduces overall metastatic burden and shifts the size distribution of metastases toward small lesions of 10 cells or less. Single seeded cells in particular seem to be protected from chemotherapy-induced killing, while larger lesions that have accumulated a desmoplastic stroma are more susceptible. Our results demonstrate that chemotherapy has direct measurable effects on metastatic burden, which may explain the improved outcomes for PDAC patients who receive adjuvant chemotherapy.

Citation Format: Nicole M. Aiello, David L. Bajor, Minh N. Pham, Robert H. Vonderheide, Ben Z. Stanger. Chemotherapy alters the natural history of metastatic progression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5176. doi:10.1158/1538-7445.AM2015-5176

Abstract PR08: Pulling out all the stops: Exploiting macropinocytosis inhibition for the treatment of pancreatic cancer

Oncogenic Ras stimulates macropinocytosis, an endocytic mechanism of fluid-phase uptake that produces large intracellular vesicles known as macropinosomes. Recently, we have linked the macropinocytic uptake of extracellular albumin and its subsequent degradation to amino acid supply and proliferation in Ras-transformed cells. The ability of albumin to serve as a nutrient source in oncogenic Ras-expressing cells is blocked by inhibiting its internalization via treatment with 5-(N-Ethyl-N-isopropyl) amiloride (EIPA). We determined that EIPA treatment diminished the growth of pancreatic tumor xenografts and that this effect was selective for tumors with a high macropinocytic index. Currently, we are exploring the feasibility of employing macropinocytosis inhibition as an anticancer therapeutic modality utilizing an autochthonous mouse model of pancreatic cancer. In these autochthonous tumors, macropinocytosis is a prominent feature of pancreatic cells found in mid- to late-stage PanIN lesions, as well as in fibroblasts and immune cells residing within the tumor stroma. We have found that EIPA treatment results in a rapid and robust reduction in proliferative capacity both in tumor cells and the surrounding stromal cells. Intriguingly, our preliminary data indicates that EIPA treatment reduces the number of activated fibroblasts associated with PanIN lesions, decreases collagen deposition and results in an increase in blood vessel diameter. Studies have demonstrated that targeting components of the extracellular matrix within the tumor stroma can cause expansion of the vasculature, which can be harnessed to improve drug delivery and permeability to the tumor. Altogether, our findings suggest that macropinocytosis inhibition could be exploited not only to target the tumor cells, but also to target the tumor stroma and enhance the delivery of chemotherapeutics.

This abstract is also presented as Poster B37.

Citation Format: Cosimo Commisso, Craig Ramirez, Rengin Soydaner-Azeloglu, David L. Bajor, Robert H. Vonderheide, Dafna Bar-Sagi. Pulling out all the stops: Exploiting macropinocytosis inhibition for the treatment of pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr PR08.

Induction of T-cell Immunity Overcomes Complete Resistance to PD-1 and CTLA-4 Blockade and Improves Survival in Pancreatic Carcinoma

Disabling the function of immune checkpoint molecules can unlock T-cell immunity against cancer, yet despite remarkable clinical success with monoclonal antibodies (mAb) that block PD-1 or CTLA-4, resistance remains common and essentially unexplained. To date, pancreatic carcinoma is fully refractory to these antibodies. Here, using a genetically engineered mouse model of pancreatic ductal adenocarcinoma in which spontaneous immunity is minimal, we found that PD-L1 is prominent in the tumor microenvironment, a phenotype confirmed in patients; however, tumor PD-L1 was found to be independent of IFNγ in this model. Tumor T cells expressed PD-1 as prominently as T cells from chronically infected mice, but treatment with αPD-1 mAbs, with or without αCTLA-4 mAbs, failed in well-established tumors, recapitulating clinical results. Agonist αCD40 mAbs with chemotherapy induced T-cell immunity and reversed the complete resistance of pancreatic tumors to αPD-1 and αCTLA-4. The combination of αCD40/chemotherapy plus αPD-1 and/or αCTLA-4 induced regression of subcutaneous tumors, improved overall survival, and conferred curative protection from multiple tumor rechallenges, consistent with immune memory not otherwise achievable. Combinatorial treatment nearly doubled survival of mice with spontaneous pancreatic cancers, although no cures were observed. Our findings suggest that in pancreatic carcinoma, a nonimmunogenic tumor, baseline refractoriness to checkpoint inhibitors can be rescued by the priming of a T-cell response with αCD40/chemotherapy.

Immune activation and a 9-year ongoing complete remission following CD40 antibody therapy and metastasectomy in a patient with metastatic melanoma

Direct immune activation via agonistic mAbs is a potentially complementary approach to therapeutic blockade of inhibitory immune receptors in cancer. Here, we provide genetic analysis of the immunologic consequences associated with the use of an agonistic CD40 mAb in a patient with metastatic melanoma who responded, underwent a single metastasectomy, and then achieved a complete remission ongoing for more than 9 years after starting therapy. Tumor microenvironment after immunotherapy was associated with proinflammatory modulations and emergence of a de novo T-cell repertoire as detected by next-generation sequencing of T-cell receptors (TCR) in the tumor and blood. The de novo T-cell repertoire identified in the posttreatment metastasectomy sample was also present-and in some cases expanded-in the circulation years after completion of therapy. Comprehensive study of this "exceptional responder" highlights the emerging potential of direct immune agonists in the next wave of cancer immunotherapies and a potential role for TCR deep sequencing in cancer immune assessment.

Abstract PR14: Lineage labeling elucidates the natural history of metastatic colonization

Compared to primary tumor formation and invasion, relatively little is known about later stages of the metastatic cascade, including the seeding and colonization of distal tissues. To visualize these late steps in metastasis, we have generated an autochthonous mouse model of pancreatic ductal adenocarcinoma in which all pancreatic epithelial cells are genetically labeled with yellow fluorescent protein (the KPCY model). This system allows for the detection of single seeded tumor cells in distant organs, as well as micrometastasis and larger lesions. We have assessed the size distribution of metastatic lesions in two frequently colonized organs, the liver and lung, and found that single cells and clusters consisting of less than ten cells represent the majority of lesions in both tissues; however these small lesions only progress to gross metastasis in the liver, not the lung. We have previously used the KPCY model to study the dynamic process of epithelial-mesenchymal transition (EMT) and its involvement in invasion and dissemination from the primary tumor. We have extended these studies to assess the role of EMT and the reverse phenomenon, mesenchymal-epithelial transition (MET), in seeding and colonization at metastatic sites. Our results suggest that while EMT is favored for entry into the circulation, there may be selection for epithelial tumor cells or MET at the metastatic site. Additionally this model allows us to investigate the parallel evolution of metastatic lesions, from single cells to macrometastasis, and the associated metastatic microenvironment.

Citation Format: Nicole M. Aiello, David L. Bajor, Robert H. Vonderheide, Ben Z. Stanger. Lineage labeling elucidates the natural history of metastatic colonization. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr PR14.

CD40 immunotherapy for pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is a highly aggressive and lethal cancer which is poorly responsive to standard therapies. Although the PDA tumor microenvironment is considered especially immunosuppressive, recent data mostly from genetically engineered and other mouse models of the disease suggest that novel immunotherapeutic approaches hold promise. Here, we describe both laboratory and clinical efforts to target the CD40 pathway for immunotherapy in PDA. Findings suggest that CD40 agonists can mediate both T-cell-dependent and T-cell-independent immune mechanisms of tumor regression in mice and patients. T-cell-independent mechanisms are associated with macrophage activation and the destruction of PDA tumor stroma, supporting the concept that immune modulation of the tumor microenvironment represents a useful approach in cancer immunotherapy.

Rehabilitation for oncogene addiction: role of immunity in cellular sobriety

Clinical responses to oncogene inhibitors result from direct effects on cell-intrinsic growth signals and disruption of downstream messages that produce a protumor immunosuppressive microenvironment. Combining oncogene-targeted and immunomodulatory therapies may result in synergistic effects, producing increased response rates and longer periods of tumor control than can be achieved with either class alone.

Clinical activity and immune modulation in cancer patients treated with CP-870,893, a novel CD40 agonist monoclonal antibody

PURPOSE

The cell-surface molecule CD40 activates antigen-presenting cells and enhances immune responses. CD40 is also expressed by solid tumors, but its engagement results in apoptosis. CP-870,893, a fully human and selective CD40 agonist monoclonal antibody (mAb), was tested for safety in a phase I dose-escalation study.

PATIENTS AND METHODS

Patients with advanced solid tumors received single doses of CP-870,893 intravenously. The primary objective was to determine safety and the maximum-tolerated dose (MTD). Secondary objectives included assessment of immune modulation and tumor response.

RESULTS

Twenty-nine patients received CP-870,893 in doses from 0.01 to 0.3 mg/kg. Dose-limiting toxicity was observed in two of seven patients at the 0.3 mg/kg dose level (venous thromboembolism and grade 3 headache). MTD was estimated as 0.2 mg/kg. The most common adverse event was cytokine release syndrome (grade 1 to 2) which included chills, rigors, and fever. Transient laboratory abnormalities affecting lymphocytes, monocytes, platelets, D-dimer and liver function tests were observed 24 to 48 hours after infusion. Four patients with melanoma (14% of all patients and 27% of melanoma patients) had objective partial responses at restaging (day 43). CP-870,893 infusion resulted in transient depletion of CD19+ B cells in blood (93% depletion at the MTD for < 1 week). Among B cells remaining in blood, we found a dose-related upregulation of costimulatory molecules after treatment.

CONCLUSION

The CD40 agonist mAb CP-870,893 was well tolerated and biologically active, and was associated with antitumor activity. Further studies of repeated doses of CP-870,893 alone and in combination with other antineoplastic agents are warranted.

High-dose carmustine, etoposide, and cisplatin for autologous stem cell transplantation with or without involved-field radiation for relapsed/refractory lymphoma: An effective regimen with low morbidity and mortality

Over a 10-year period (January 1993 to October 2002), 101 relapsed or refractory non-Hodgkin lymphoma patients were treated at our center with high-dose chemotherapy and autologous transplantation. The median patient age was 54 years (range, 25-70 years). Thirty-two patients had indolent (low-grade), 42 had aggressive (intermediate-grade), and 27 had very aggressive (high-grade) non-Hodgkin lymphoma. Thirty-six patients had primary refractory disease, 20 had a chemoresistant relapse, 35 patients had a chemosensitive relapse, and 10 patients were "initial high risk" patients. The median number of prior chemotherapy regimens was 2 (range, 1-5). The preparative regimen (BEP) was bischloroethylnitrosourea (BCNU) 600 mg/m 2 , etoposide 2400 mg/m 2 , and Platinol (cisplatin) 200 mg/m 2 given intravenously over 5 days. Within 3 weeks before transplantation, 70 patients received involved-field radiotherapy (IFR) 20 Gy to sites of currently active (>2 cm) or prior bulky (>5 cm) disease. Most patients (n = 93) received mobilized peripheral blood stem cells (median CD34 + cell dose, 6.7 x 10 6 /kg). Median neutrophil (>500/microL) and platelet (>20 000/microL, untransfused) recoveries were 11 days (range, 7-19 days) and 14 days (range, 7-36 days), respectively. At a median follow-up of 41 months (range, 4 to 118 months) for survivors, Kaplan-Meier 5-year probabilities of overall survival (OS) and disease-free survival (DFS) were 58.6% and 51.1%, respectively. Four patients (4%) died within 30 days of stem cell infusion (1 pulmonary embolism, 2 septicemias with multiorgan failure, and 1 progressive lymphoma). Two patients (2%) developed interstitial pneumonitis most likely secondary to high-dose BCNU. Three cases (3%) of secondary acute myelogenous leukemia occurred. On multivariate analysis, age (<60 or > or =60 years), histologic grade (low versus intermediate or high), the use of IFR, and chemotherapy response at baseline did not affect OS or DFS. Of 70 patients given IFR, 27 relapsed: 10 (37%) within and 17 (63%) outside the radiation field. The use of IFR did not affect either OS or DFS, probably because IFR was offered to patients with bulky or chemoresistant disease. BEP with or without IFR is a highly effective and well-tolerated regimen in the relapsed/refractory lymphoma setting. It has low morbidity and transplant-related mortality and a low incidence (3%) of posttransplantation malignancy.