Immune landscape of tertiary lymphoid structures in hepatocellular carcinoma (HCC) treated with neoadjuvant immune checkpoint blockade

Neoadjuvant immunotherapy is thought to produce long-term remissions through induction of antitumor immune responses before removal of the primary tumor. Tertiary lymphoid structures (TLS), germinal center-like structures that can arise within tumors, may contribute to the establishment of immunological memory in this setting, but understanding of their role remains limited. Here, we investigated the contribution of TLS to antitumor immunity in hepatocellular carcinoma (HCC) treated with neoadjuvant immunotherapy. We found that neoadjuvant immunotherapy induced the formation of TLS, which were associated with superior pathologic response, improved relapse free survival, and expansion of the intratumoral T and B cell repertoire. While TLS in viable tumor displayed a highly active mature morphology, in areas of tumor regression we identified an involuted TLS morphology, which was characterized by dispersion of the B cell follicle and persistence of a T cell zone enriched for ongoing antigen presentation and T cell-mature dendritic cell interactions. Involuted TLS showed increased expression of T cell memory markers and expansion of CD8+ cytotoxic and tissue resident memory clonotypes. Collectively, these data reveal the circumstances of TLS dissolution and suggest a functional role for late-stage TLS as sites of T cell memory formation after elimination of viable tumor.

Gemcitabine, Docetaxel, Capecitabine, Cisplatin, Irinotecan as First-line Treatment for Metastatic Pancreatic Cancer

Purpose

Treatment of advanced pancreatic cancer with a single therapeutic at a maximal dose has been largely ineffective at increasing survival. Combination therapies are commonly studied but often limited by toxicity. We previously showed that low-dose multiagent therapy with gemcitabine, docetaxel (taxotere), capecitabine (xeloda), and cisplatin (GTX-C) was safe, well tolerated, and effective (NCT01459614). Here, we hypothesize that adding irinotecan to GTX-C may improve survival with minimal toxicity.

Experimental Design

Patients with treatment-naïve metastatic pancreatic adenocarcinoma were treated with gemcitabine, docetaxel (taxotere), capecitabine (xeloda), cisplatin, and irinotecan (GTX-CI). Treatment consisted of capecitabine 500 mg twice daily on days 1-14 and gemcitabine 300 to 500 mg/m2, docetaxel 20 mg/m2, cisplatin 15 to 20 mg/m2, and irinotecan 20 to 60 mg/m2 on days 4 and 11 of a 21-day cycle. The primary objective was 9-month overall survival (OS). Secondary objectives included response rate (RR), disease control rate (DCR), progression-free survival (PFS), and OS.

Results

The regimen was well tolerated. The recommended phase II dose was gemcitabine 500 mg/m2, docetaxel 20 mg/m2, capecitabine 500 mg po bid, cisplatin 20 mg/m2, and irinotecan 20 mg/m2. Median follow-up in phase II was 11.02 months (2.37-45.17). Nine-month OS rate was 57% [95% confidence interval (CI): (41-77)]. RR was 57% [95% CI: (37-75) 50% PR and 7% CR]. DCR was 87% [95% CI: (69-96)]. Median OS and PFS were 11.02 [95% CI: (8.54-21.09)] and 8.34 [95% CI: (6.34-NA)] months, respectively.

Conclusions

The addition of irinotecan to GTX-C was safe and well tolerated. While the study did not meet its primary objective, the responses were clinically meaningful using a well-tolerated regimen.

Significance

We aimed to optimize the previously reported efficacious regimen of low-dose multiagent therapy with GTX-C for the treatment of metastatic pancreatic ductal adenocarcinoma by adding irinotecan. The primary objective was not met, but GTX-CI was well tolerated. The RR of 57%, median PFS of 8.3 months, median OS of 11 months, and 36-month OS rate of 19% suggest clinical benefit. Further optimization of this regimen is warranted.

Phase I Trial of Intravenous Mistletoe Extract in Advanced Cancer

Purpose

Mistletoe extract (ME) is widely used for patients with cancer to support therapy and to improve quality of life (QoL). However, its use is controversial due to suboptimal trials and a lack of data supporting its intravenous administration.

Materials and Methods

This phase I trial of intravenous mistletoe (Helixor M) aimed to determine the recommended phase II dosing and to evaluate safety. Patients with solid tumor progressing on at least one line of chemotherapy received escalating doses of Helixor M three times a week. Assessments were also made of tumor marker kinetics and QoL.

Results

Twenty-one patients were recruited. The median follow-up duration was 15.3 weeks. The MTD was 600 mg. Treatment-related adverse events (AE) occurred in 13 patients (61.9%), with the most common being fatigue (28.6%), nausea (9.5%), and chills (9.5%). Grade 3+ treatment-related AEs were noted in 3 patients (14.8%). Stable disease was observed in 5 patients who had one to six prior therapies. Reductions in baseline target lesions were observed in 3 patients who had two to six prior therapies. Objective responses were not observed. The disease control rate (percentage of complete/partial response and stable disease) was 23.8%. The median stable disease was 15 weeks. Serum cancer antigen-125 or carcinoembryonic antigen showed a slower rate of increase at higher dose levels. The median QoL by Functional Assessment of Cancer Therapy-General increased from 79.7 at week 1 to 93 at week 4.

Conclusions

Intravenous mistletoe demonstrated manageable toxicities with disease control and improved QoL in a heavily pretreated solid tumor population. Future phase II trials are warranted.

Significance

Although ME is widely used for cancers, its efficacy and safety are uncertain. This first phase I trial of intravenous mistletoe (Helixor M) aimed to determine phase II dosing and to evaluate safety. We recruited 21 patients with relapsed/refractory metastatic solid tumor. Intravenous mistletoe (600 mg, 3/week) demonstrated manageable toxicities (fatigue, nausea, and chills) with disease control and improved QoL. Future research can examine ME's effect on survival and chemotherapy tolerability.

A randomized, phase II trial of oral azacitidine (CC-486) in patients with resected pancreatic adenocarcinoma at high risk for recurrence

BACKGROUND

Of the only 20% of patients with resectable pancreatic ductal adenocarcinoma (rPDA), cancer recurs in 80% of cases. Epigenetic dysregulation is an early hallmark of cancer cells acquiring metastatic potential, and epigenetic modulators may reactivate tumor suppressor genes, delay recurrence, and sensitize PDA to future chemotherapy.

METHODS

This was a randomized phase II study (NCT01845805) of CC-486 (oral DNA methyltransferase inhibitor azacitidine) vs. observation (OBS) in rPDA patients harboring high-risk features (stage pN1-2, R1 margins, or elevated CA 19-9 level) with no evidence of disease following standard adjuvant therapy. Patients were randomized to oral CC-486 treatment (300 mg daily on days 1-21 on a 28-day cycle) or OBS for up to 12 cycles or until disease relapse/unacceptable toxicities. Following recurrence, records of next-line therapies, imaging, and survival were obtained. The primary endpoint was progression-free survival (PFS)-time from randomization to recurrence (imaging/biopsy confirmed or death). Secondary endpoints included OS and PFS and ORR and metastatic PFS with subsequent next-line systemic therapy in metastatic setting.

RESULTS

Forty-nine patients (24 in CC-486 arm, 25 in OBS arm) were randomized: median age 66 (range 36-81), 53% male, 73% node positive, 49% elevated CA 19-9, 20% R1 resection, 63% and 100% received perioperative concurrent chemoradiation and chemotherapy, respectively. Median time from surgery to randomization was 9.6 mo (range 2.9-36.8). For the CC-486 arm, median treatment duration was 5.6 mo (range 1.3 to 12.8) with 14 treatment-related grade 3 or 4 AEs among 5 patients (22%) resulting in dose-reduction. Four patients (17%) discontinued therapy due to AEs. With median follow-up of 20.3mo (IQR 12.8, 41.4), 38 (79%) of evaluable patients recurred (34 imaging-confirmed, 4 clinically). Median PFS in imagining-confirmed cases was 9.2 and 8.9mo (HR 0.94, 95% CI 0.46-1.87, p = 0.85) for CC-486 and OBS patients, respectively. Median OS (2-yr OS%) was 33.8 (50%) and 26.4 mo (61%) in CC-486 and OBS patients, respectively. (HR 0.98, 95% CI 0.46-2.05, p = 0.96). ORR with subsequent chemotherapy in the metastatic setting was minimal in both arms.

CONCLUSIONS

Treatment with CC-486 following adjuvant therapy did not prolong time-to-relapse in patients with high-risk rPDA or improve disease response on 1st-line metastatic therapy.

Multi-omic analyses of changes in the tumor microenvironment of pancreatic adenocarcinoma following neoadjuvant treatment with anti-PD-1 therapy

Successful pancreatic ductal adenocarcinoma (PDAC) immunotherapy necessitates optimization and maintenance of activated effector T cells (Teff). We prospectively collected and applied multi-omic analyses to paired pre- and post-treatment PDAC specimens collected in a platform neoadjuvant study of granulocyte-macrophage colony-stimulating factor-secreting allogeneic PDAC vaccine (GVAX) vaccine ± nivolumab (anti-programmed cell death protein 1 [PD-1]) to uncover sensitivity and resistance mechanisms. We show that GVAX-induced tertiary lymphoid aggregates become immune-regulatory sites in response to GVAX + nivolumab. Higher densities of tumor-associated neutrophils (TANs) following GVAX + nivolumab portend poorer overall survival (OS). Increased T cells expressing CD137 associated with cytotoxic Teff signatures and correlated with increased OS. Bulk and single-cell RNA sequencing found that nivolumab alters CD4+ T cell chemotaxis signaling in association with CD11b+ neutrophil degranulation, and CD8+ T cell expression of CD137 was required for optimal T cell activation. These findings provide insights into PD-1-regulated immune pathways in PDAC that should inform more effective therapeutic combinations that include TAN regulators and T cell activators.

Neoadjuvant and adjuvant antitumor vaccination alone or combination with PD1 blockade and CD137 agonism in patients with resectable pancreatic adenocarcinoma

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Background: Utilizing a vaccine that induces and activates host effector T cells and co-administering it with immune modulating agents that enhance anti-tumor T cell activity is a potential strategy for overcoming pancreatic adenocarcinoma’s (PDA) resistance to immunotherapy. Our prior clinical trial demonstrated a GM-CSF-secreting, allogeneic tumor cell vaccine (GVAX) increases infiltrating CD8+ T cells in PDA. Follow up preclinical work demonstrated therapeutic synergy between GVAX and PD-1inhibition (PD1) with efficacy further enhanced by CD137 agonism (CD137). Methods: This was a 3-arm trial of neoadjuvant & adjuvant GVAX-based therapy in resectable (r) PDA patients (pts). Adults with clinically resectable, untreated PDA were enrolled in 1 of 3 study treatments: Arm A (GVAX alone), Arm B (GVAX + PD1 [Nivolumab]), or arm C (GVAX + PD1 + CD137 [Urelumab]). Treatment was given as follows: Day 1 - Cyclophosphamide 200mg/m2 IV (All Arms), Nivolumab 480mg IV (Arms B, C), Urelumab 8mg IV (Arm C); Day 2 – GVAX ID (All Arms). Pts were treated at 3 timepoints: 1) once 2 weeks prior to surgery; 2) once post-surgical recovery prior to standard of care adjuvant chemotherapy (SOC); 3) every month (up to 4 mo) following completion of SOC (if disease-free). SOC regimes included (m)FOLFIRINOX, Gem +/- Cap/NAB-Paclitaxel. The study was powered for a primary biologic endpoint: treatment-related change in intratumoral CD8+CD137+ T cells. Clinical endpoints included disease-free survival (DFS: time from surgery to recurrence), overall survival (OS: time from surgery to death), and safety. Results: 38 pts (N = 15 [Arm A], N = 13 [Arm B], N = 10 [Arm C]) were eligible for efficacy analysis (had R0/R1 resection) and 45 pts (N = 17 [A], N = 17 [B], N = 11 [C]) were eligible for safety analysis (had ≥1 dose of study treatment). Demographics, surgical pathology features, and SOC durations were similar in all Arms. At median follow up of 23 mo [A], 26 mo [B], and 22 mo [C], median DFS (95% CI) was 14.82 mo (6.0, NA), 16.23 mo (7.49, NA) and not reached (16.33, NA) for Arms A, B, C, respectively. There was no DFS benefit to adding PD1 compared to GVAX alone (HR 0.98 [95% CI 0.42, 2.27], p = 0.96). Combination CD137 + PD1 + GVAX was associated with marginally significant improved DFS compared to GVAX alone (HR 0.38 [95%CI 0.12, 1.19], p = 0.097) and GVAX + PD1 (HR 0.38 [95%CI 0.12, 1.21], p = 0.103). Median OS (95% CI) was 25.0 mo (18.8, NA), 26.4 mo (20.3, NA), and not yet reached for Arms A, B, C, respectively. There were no serious adverse events. In Arm C, 1 pt had grade 3 rash that delayed treatment and there was 1 instance of grade 2 AST/ALT elevation. The biologic endpoint will be reported at the meeting. Conclusions: Despite a small sample size, combining GVAX with dual immune-targeting of PD-1 blockade and CD137 agonism was safe and may enhance DFS in rPDA pts treated in the perioperative and post-adjuvant settings. Clinical trial information: NCT02451982.

Tim-4+ cavity-resident macrophages impair anti-tumor CD8+ T cell immunity

Immune checkpoint blockade (ICB) has been a remarkable clinical advance for cancer; however, the majority of patients do not respond to ICB therapy. We show that metastatic disease in the pleural and peritoneal cavities is associated with poor clinical outcomes after ICB therapy. Cavity-resident macrophages express high levels of Tim-4, a receptor for phosphatidylserine (PS), and this is associated with reduced numbers of CD8+ T cells with tumor-reactive features in pleural effusions and peritoneal ascites from patients with cancer. We mechanistically demonstrate that viable and cytotoxic anti-tumor CD8+ T cells upregulate PS and this renders them susceptible to sequestration away from tumor targets and proliferation suppression by Tim-4+ macrophages. Tim-4 blockade abrogates this sequestration and proliferation suppression and enhances anti-tumor efficacy in models of anti-PD-1 therapy and adoptive T cell therapy in mice. Thus, Tim-4+ cavity-resident macrophages limit the efficacy of immunotherapies in these microenvironments.

Feasibility and efficacy of neoadjuvant cabozantinib and nivolumab in patients with borderline resectable or locally advanced hepatocellular carcinoma (HCC)

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Background: Only 10-15% of newly diagnosed HCC patients are candidates for a potentially curative resection, and most patients who receive resection eventually recur. Historical systemic therapies including sorafenib, as well as locoregional therapies, have not demonstrated benefit in the perioperative setting. Novel combinations of targeted therapies and immunotherapies demonstrate higher response rates than sorafenib in HCC. Here, we report the feasibility and efficacy of neoadjuvant combination therapy with cabozantinib plus nivolumab, followed by surgical resection, in patients with borderline resectable or locally advanced HCC. Methods: We conducted an open-label, single-arm, phase I study in patients with HCC with borderline resectable or locally advanced HCC (including multinodular disease, portal vein involvement, or other high-risk features). Patients received 8 weeks of therapy with cabozantinib 40 mg oral daily plus nivolumab 240 mg IV every two weeks, followed by restaging and possible surgical resection. The primary endpoint was feasibility, defined by the percentage of patients experiencing a treatment-related adverse event that precluded continuing on to surgery within 60 days of the planned date for surgical evaluation. Results: We enrolled 15 patients of whom 14 patients completed neoadjuvant therapy and underwent surgical evaluation. Adverse events were consistent with prior experience with these agents, and the trial met its primary endpoint, with no patients experiencing a treatment-related adverse event that precluded timely surgical assessment. Of patients completing neoadjuvant therapy, 1 patient declined surgery, 1 tumor could not be resected, and 12 patients underwent successful R0 surgical resection. 5/12 (41.7%) resected patients had a major or complete pathologic response. At a median follow up of one year, 4/5 pathologic responders are without recurrence. We performed an in-depth profiling of the surgical resection biospecimens and identified an enrichment of IFNγ+ effector memory CD4+ and granzyme B+ effector CD8+ T cells as well as tertiary lymphoid aggregates in the pathologic responders. We further analyzed the spatial relationships of cell types in responders and non-responders, which identified distinct spatial arrangement of B cells in responders, and proximity of arginase-1 expressing myeloid cells to T cells in nonresponders. Conclusions: This study is, to our knowledge, the first use of a targeted therapy in combination with an immune checkpoint inhibitor in the neoadjuvant setting in HCC, and the first use of modern systemic therapies to expand surgical resection criteria. Neoadjuvant cabozantinib and nivolumab is feasible, and may result in pathologic responses and long-term disease-free survival in a group of patients who may be outside traditional resection criteria. Clinical trial information: NCT03299946.

Vaccine-Induced Intratumoral Lymphoid Aggregates Correlate with Survival Following Treatment with a Neoadjuvant and Adjuvant Vaccine in Patients with Resectable Pancreatic Adenocarcinoma

PURPOSE

Immunotherapy is currently ineffective for nearly all pancreatic ductal adenocarcinomas (PDAC), largely due to its tumor microenvironment (TME) that lacks antigen-experienced T effector cells (Teff). Vaccine-based immunotherapies are known to activate antigen-specific Teffs in the peripheral blood. To evaluate the effect of vaccine therapy on the PDAC TME, we designed a neoadjuvant and adjuvant clinical trial of an irradiated, GM-CSF-secreting, allogeneic PDAC vaccine (GVAX).

PATIENTS AND METHODS

Eighty-seven eligible patients with resectable PDAC were randomly assigned (1:1:1) to receive GVAX alone or in combination with two forms of low-dose cyclophosphamide. Resected tumors following neoadjuvant immunotherapy were assessed for the formation of tertiary lymphoid aggregates (TLA) in response to treatment. The clinical endpoints are disease-free survival (DFS) and overall survival (OS).

RESULTS

The neoadjuvant treatment with GVAX either alone or with two forms of low-dose cyclophosphamide is safe and feasible without adversely increasing the surgical complication rate. Patients in Arm A who received neoadjuvant and adjuvant GVAX alone had a trend toward longer median OS (35.0 months) than that (24.8 months) in the historical controls who received adjuvant GVAX alone. However, Arm C, who received low-dose oral cyclophosphamide in addition to GVAX, had a significantly shorter DFS than Arm A. When comparing patients with OS > 24 months to those with OS < 15 months, longer OS was found to be associated with higher density of intratumoral TLA.

CONCLUSIONS

It is safe and feasible to use a neoadjuvant immunotherapy approach for PDACs to evaluate early biologic responses. In-depth analysis of TLAs is warranted in future neoadjuvant immunotherapy clinical trials.

Abstract PR-004: Systemic and intratumoral immune profiling in metastatic pancreatic cancer patients who received front-line FOLFIRINOX and were treated with combination immunotherapy with CTLA-4 blockade in the maintenance setting

Background: Metastatic pancreatic ductal adenocarcinoma (PDA) has a dismal prognosis with a 5-year survival rate of 10%. For patients with metastatic PDA who respond to but cannot tolerate multi-agent chemotherapy, such as FOLFIRINOX, beyond 4-6 months, the optimal approach is unknown. Few studies have evaluated immunotherapy in the maintenance setting for PDA. Previously, a phase 2 trial in advanced PDA showed the promise of a GM-CSF-secreting allogeneic pancreatic tumor cell-based vaccine (GVAX) with CTLA-4 inhibitor, ipilimumab (IPI) [1]. Here we describe the first clinical testing of GVAX + IPI in the maintenance setting for patients with metastatic PDA who had ongoing response or stable disease after front-line FOLFIRINOX and evaluation of immune cell changes within the peripheral blood and tumor. Methods: From 40 vaccinated patients, we obtained paired peripheral blood lymphocytes (PBLs) from 20 patients and metastatic PDA biopsies from 6 of these 20 patients at baseline and week 7 (after at least two doses of GVAX + IPI). Samples were stratified into “stable” or “progressive” cohorts based on disease status on first restaging scan. To profile peripheral immune responses to treatment, we performed mass cytometry (CyTOF) analysis using a T cell-focused panel on PBLs. To profile intratumoral immune responses, biopsies containing &gt;30% tumor cellularity were chosen for 10-plex multiplex immunohistochemistry with T cell and myeloid cell-focused panels allowing us to examine changes in immune cell subsets after GVAX + IPI. Results. GVAX + IPI led to noticeable changes in PBLs including increases in T helper and cytotoxic effector memory cells and decrease in naïve cytotoxic T cells, regardless of disease status. Among co-inhibitory markers assayed on PBLs, GVAX + IPI upregulated TIM3 and PD-1 in most helper and cytotoxic T cells, while CTLA-4 was largely maintained. Interrogation of the metastatic tumor microenvironment at baseline and on-treatment revealed significant increases in CD8+ T cells and pro-inflammatory M1 macrophages and decrease in pro-tumor M2 macrophages. Based on the CD8+ T cell functional status, there were increases in late effector (EOMES-PD-1+) and memory (EOMES-PD-1-) CD8+ T cells in the metastatic tumor after immunotherapy. Conclusions: In summary, we have proposed a mechanism for our immunotherapy in the maintenance setting. GVAX may be inducing systemic and intratumoral activation of naïve T cells to antigen-specific T cells and promoting a decrease in immunosuppressive cells in the metastatic PDA microenvironment. Meanwhile, IPI may be blocking CTLA-4, which improves priming of T cells, but also may be leading to upregulation of regulatory markers TIM3 and PD-1 on T cell subsets as a compensatory mechanism. This trial highlights the challenge to inducing effective anti-tumor immune responses in metastatic PDA with inducible counterregulatory mechanisms. These compensatory increases could provide targets for the next generation of studies. 1Le DT, et al. J Immunother. 2013

Citation Format: Annie A. Wu, Katherine M. Bever, Won Jin Ho, Elana J. Fertig, Nan Niu, Lei Zheng, Rose M. Parkinson, Jennifer N. Durham, Beth Onners, Anna K. Ferguson, Cara Wilt, Andrew H. Ko, Andrea Wang-Gillam, Daniel A. Laheru, Robert A. Anders, Elizabeth D. Thompson, Elizabeth A. Sugar, Elizabeth M. Jaffee, Dung T. Le. Systemic and intratumoral immune profiling in metastatic pancreatic cancer patients who received front-line FOLFIRINOX and were treated with combination immunotherapy with CTLA-4 blockade in the maintenance setting [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PR-004.

Evaluation of Cyclophosphamide/GVAX Pancreas Followed by Listeria-Mesothelin (CRS-207) with or without Nivolumab in Patients with Pancreatic Cancer

PURPOSE

Two studies in previously treated metastatic pancreatic cancer have been completed combining GVAX pancreas vaccine (GM-CSF-secreting allogeneic pancreatic tumor cells) with cyclophosphamide (Cy) and CRS-207 (live, attenuated Listeria monocytogenes-expressing mesothelin). In the current study, we compared Cy/GVAX followed by CRS-207 with (Arm A) or without nivolumab (Arm B).

PATIENTS AND METHODS

Patients with pancreatic adenocarcinoma who received one prior therapy for metastatic disease and RECIST measurable disease were randomized 1:1 to receive treatment on Arm A or Arm B. The primary objective was to compare overall survival (OS) between the arms. Additional objectives included assessment of progression-free survival, safety, tumor responses, CA19-9 responses, and immunologic correlates.

RESULTS

Ninety-three patients were treated (Arm A, 51; Arm B, 42). The median OS in Arms A and B were 5.9 [95% confidence interval (CI), 4.7-8.6] and 6.1 (95% CI, 3.5-7.0) months, respectively, with an HR of 0.86 (95% CI, 0.55-1.34). Objective responses were seen in 3 patients using immune-related response criteria (4%, 2/51, Arm A; 2%, 1/42, Arm B). The grade ≥3 related adverse event rate, whereas higher in Arm A (35.3% vs. 11.9%) was manageable. Changes in the microenvironment, including increase in CD8+ T cells and a decrease in CD68+ myeloid cells, were observed in long-term survivors in Arm A only.

CONCLUSIONS

Although the study did not meet its primary endpoint of improvement in OS of Arm A over Arm B, the OS was comparable with standard therapy. Objective responses and immunologic changes in the tumor microenvironment were evident.

A Phase II Study of Allogeneic GM-CSF-Transfected Pancreatic Tumor Vaccine (GVAX) with Ipilimumab as Maintenance Treatment for Metastatic Pancreatic Cancer

PURPOSE

This phase II study tested granulocyte-macrophage colony-stimulating factor (GM-CSF)-allogeneic pancreatic tumor cells (GVAX) and ipilimumab in metastatic pancreatic ductal adenocarcinoma (PDA) in the maintenance setting.

PATIENTS AND METHODS

Patients with PDA who were treated with front-line chemotherapy consisting of 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) in the metastatic setting and had ongoing response or stable disease after 8-12 doses were eligible. Patients were randomized 1:1 to treatment with GVAX and ipilimumab given every 3 weeks for four doses then every 8 weeks (Arm A) or to FOLFIRINOX continuation (Arm B). The primary objective was to compare overall survival (OS) between the two arms.

RESULTS

Eighty-two patients were included in the final analysis (Arm A: 40; Arm B: 42). The study was stopped for futility after interim analysis. Median OS was 9.38 months [95% confidence interval (CI), 5.0-12.2] for Arm A and 14.7 months (95% CI, 11.6-20.0) for Arm B (HR, 1.75; P = 0.019). Using immune-related response criteria, two partial responses (5.7%) were observed in Arm A and four (13.8%) in Arm B. GVAX + ipilimumab promoted T-cell differentiation into effector memory phenotypes both in the periphery and in the tumor microenvironment and increased M1 macrophages in the tumor.

CONCLUSIONS

GVAX and ipilimumab maintenance therapy did not improve OS over continuation of chemotherapy and resulted in a numerically inferior survival in metastatic PDA. However, clinical responses and biological effects on immune cells were observed. Further study of novel combinations in the maintenance treatment of metastatic PDA is feasible.

An exploratory study of metformin with or without rapamycin as maintenance therapy after induction chemotherapy in patients with metastatic pancreatic adenocarcinoma

Purpose: Metformin combined with the mTOR inhibitor rapamycin showed potential synergistic anti-tumor activity in preclinical studies in pancreatic ductal adenocarcinoma (PDA). This phase 1b study (NCT02048384) was conducted to evaluate the feasibility and activity of metformin +/– rapamycin in the maintenance setting for unselected patients with metastatic PDA (mPDA) treated with chemotherapy.

Materials and Methods: Eligible patients with stable or responding mPDA after ≥ 6 months on chemotherapy were randomized 1:1 to metformin alone (Arm A) or with rapamycin (Arm B), stratified by prior treatment with FOLFIRINOX. Fluorodeoxyglucose (FDG) PET scans and peripheral blood mononuclear cells were obtained for exploratory analyses.

Results: 22 subjects (11 per arm) received treatment per protocol. Median PFS/OS were 3.5 and 13.2 months respectively, with 2 year OS rate of 37%; there were no differences between arms. No responses were observed by RECIST; however, decreases in FDG avidity and/or CA19-9 were observed in several long-term survivors. Treatment related adverse events of Grade ≥ 3 occurred in 0% vs 27% of patients in Arm A vs B and were asymptomatic hematologic or electrolyte abnormalities that were not clinically significant. Improved survival was associated with low baseline neutrophil: lymphocyte ratio, baseline lack of assessable disease by PET, and greater expansion of dendritic cells following treatment.

Conclusions: Metformin +/– rapamycin maintenance for mPDA was well-tolerated and several patients achieved stable disease associated with exceptionally long survival. Further prospective studies are needed to clarify the role of these agents in the maintenance setting and to enhance patient selection for such approaches.

A clinical study of tremelimumab alone or in combination with olaparib in patients with advanced epithelial ovarian cancer

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Background: Single agent immunotherapy (IO) has shown only modest clinical activity for the treatment of ovarian cancer. The combination of anti-programmed death-1 and PARP inhibitors showed promising activity in early trials. Here, we report the results of an open-label, parallel arm, dose escalation study of tremelimumab (T) alone or in combination with olaparib (O) in patients (pts) with advanced epithelial ovarian cancer (EOC). Methods: Pts with recurrent/persistent EOC who had progression < 12 months from last platinum exposure were enrolled. Prior therapy with IO (except anti-CTLA-4) or PARP inhibitor was allowed. Pts were randomized to either T 10mg/kg every 4 weeks (wks) x 7 then every 12 wks (Arm A) or T with O twice daily at three planned dose levels (Arm B). The primary objectives were safety, pharmacodynamic (PD) change in CD4+ICOShi peripheral T cells by flow cytometry, and identification of the optimal dose combination of T with O. Secondary objectives included 6-month progression-free survival (PFS6) and objective response rate (ORR). Results: A total of 24 pts were treated, 12 on Arm A, and 12 on two Arm B dose levels. Pts had a median age of 60 years (range 44-81). Histologic subtypes included high-grade serous EOC (20 pts, 83%), clear cell (3 pts, 13%), and moderately-differentiated adenocarcinoma (1 pt, 4%). BRCA1 mutation (mt) was present in 2 cases, BRCA2 mt in 1. Median number of prior regimens was 3.5 (range 1-9). Most adverse events (AEs) were attributable to T, the most common grade 3 toxicities were rash (13%), immune-mediated hepatitis (8%), and colitis (8%). No grade ≥4 toxicities were identified. Immune-mediated AEs also included acute kidney injury, hypophysitis, and hypothyroidism. No dose limiting toxicities were identified on Arm B. Two pts in Arm B had >PFS6. Of 20 pts evaluable for response, there was 1 partial response (Arm B), and 9 pts had stable disease (6 on Arm A, 3 on Arm B). Mean percentage of CD4+ICOShi T cells was significantly increased on Days 15 and 22 compared to Day 1 at both T dose levels (Table).T at 3 mg/kg with O at 150mg is the optimal dose of those tested. Conclusions: T and T with O was tolerable, with modest clinical activity in this pt population. AEs were as expected, and peripheral CD4+ICOShi T cells increased on therapy. Clinical trial information: 02485990. [Table: see text]

T-Cell Infiltration and Adaptive Treg Resistance in Response to Androgen Deprivation With or Without Vaccination in Localized Prostate Cancer

PURPOSE

Previous studies suggest that androgen deprivation therapy (ADT) promotes antitumor immunity in prostate cancer. Whether a vaccine-based approach can augment this effect remains unknown.

PATIENTS AND METHODS

We conducted a neoadjuvant, randomized study to quantify the immunologic effects of a GM-CSF-secreting allogeneic cellular vaccine in combination with low-dose cyclophosphamide (Cy/GVAX) followed by degarelix versus degarelix alone in patients with high-risk localized prostate adenocarcinoma who were planned for radical prostatectomy.

RESULTS

Both Cy/GVAX plus degarelix and degarelix alone led to significant increases in intratumoral CD8⁺ T-cell infiltration and PD-L1 expression as compared with a cohort of untreated, matched controls. However, the CD8⁺ T-cell infiltrate was accompanied by a proportional increase in regulatory T cells (Treg), suggesting that adaptive Treg resistance may dampen the immunogenicity of ADT. Although Cy/GVAX followed by degarelix was associated with a modest improvement in time-to-PSA progression and time-to-next treatment, as well as an increase in PD-L1, there was no difference in the CD8⁺ T-cell infiltrate as compared with degarelix alone. Gene expression profiling demonstrated that CHIT1, a macrophage marker, was differentially upregulated with Cy/GVAX plus degarelix compared with degarelix alone.

CONCLUSIONS

Our results highlight that ADT with or without Cy/GVAX induces a complex immune response within the prostate tumor microenvironment. These data have important implications for combining ADT with immunotherapy. In particular, our finding that ADT increases both CD8⁺ T cells and Tregs supports the development of regimens combining ADT with Treg-depleting agents in the treatment of prostate cancer.

An exploratory study of metformin (Met) with or without rapamycin (Rapa) as maintenance therapy after induction chemotherapy in patients (Pts) with metastatic pancreatic adenocarcinoma (PDA)

700

Background: Few studies have examined maintenance therapy in unselected pts with metastatic PDA (mPDA). mTOR signaling is central to several oncogenic pathways in PDA and also has a role in T cell differentiation and activation, and we hypothesized a role for mTOR inhibition (mTORi) in the maintenance setting. Methods: This was a randomized open-label study conducted at 2 sites. Eligible pts had mPDA with stable disease for ≥6 months on chemotherapy and ECOG PS 0/1. Pts were randomized 1:1 to Met 850mg BID alone (Arm A) or with Rapa 4mg daily (Arm B), stratified by prior FOLFIRINOX. Baseline and on-treatment PET scans and peripheral blood mononuclear cells were obtained for exploratory analyses. Results: 23 pts were randomized. Median age was 64 (range 34-77) and 82% had ECOG PS 1. 12 of 23 received prior FOLFIRINOX; 8 received >1 prior line of therapy. 22 subjects (11 per arm) were treated per protocol. Treatment related adverse events of Grade ≥3 were seen in 0% vs 27% of pts in Arm A vs B and were all asymptomatic hematologic or electrolyte abnormalities that were not clinically significant. Median PFS/OS were 3.5 (95% CI: 2.9-9.2)/13.2 mos (95% CI: 7.8 to not reached) respectively, with 2 yr OS rate of 37% (95% CI: 21-66%); there were no differences between treatment arms. As expected in the maximally debulked setting, no responses were observed by RECIST; however, decreases in FDG avidity and/or CA199 were observed in several long-term survivors. Better survival was associated with low baseline neutrophil to lymphocyte ratio, baseline lack of assessable disease by PET, and with expansion of dendritic cells following treatment. Compared to Met alone, Met + Rapa was associated with decreased mTOR activity on some immune cell subsets and decreased metabolic fitness, but this was not correlated with outcome. Conclusions: Met +/- rapa maintenance for mPDA was well-tolerated and several pts achieved stable disease associated with exceptionally long survival. Further prospective studies are needed to clarify the role of mTORi in the maintenance setting and to enhance pt selection for such approaches. Clinical trial information: NCT02048384.

Phase II study of nivolumab and relatlimab in advanced mismatch repair deficient (dMMR) cancers resistant to prior PD-(L)1 inhibition

TPS839

Background: Cancers deficient in DNA mismatch repair (dMMR) are highly immunogenic tumors exhibiting high rates of response to immune checkpoint inhibitors targeting the programmed cell death-1 (PD-1)/PD-1 ligand (PD-L1) interaction. These tumors are characterized by high levels of microsatellite instability (MSI-H) and an exceptionally high tumor mutation burden, thought to underlie responsiveness to immunotherapy, with higher predicted immunogenicity of mutation-associated neoantigens. However, primary and acquired resistance are observed and diversity in responses is not fully explained by variations in mutation burden. Other immune checkpoints may be acting in parallel with PD-1/PD-L1. In particular, lymphocyte activation gene 3 (LAG3) mediates exhaustion of activated T cells and may have a role in resistance to PD-(L)1 inhibitors (PD-(L)1i); therefore, we hypothesized that the addition of LAG3 inhibitor (relatlimab) to the PD-1i nivolumab may overcome resistance in these tumors. Methods: Patients with advanced dMMR/MSI-H cancer who have progressive disease (by RECIST 1.1) during or within 6 months of PD-(L)1i containing therapy, and after at least 12 weeks of therapy, and meet other eligibility will be enrolled. All patients will receive nivolumab 480mg + relatlimab 160mg every 4 weeks until intolerance or progression, or up to a maximum of 2 years. The primary endpoint is objective response rate. Key secondary endpoints include safety, progression free and overall survival, and other response endpoints as measured by RECIST 1.1 and iRECIST criteria. Exploratory objectives will include analysis of the tumor microenvironment on biopsies obtained at baseline and on-treatment, analysis of T cell populations in the tumor and in the periphery and functional characterization of mutation-associated neoantigen-specific T cells. Studies of the microbiome will be conducted on stool and oral wash samples. Enrollment of 21 patients is planned. Clinical trial information: NCT03607890.

A phase 2 study of GVAX colon vaccine with cyclophosphamide and pembrolizumab in patients with mismatch repair proficient advanced colorectal cancer

Background

Mismatch repair proficient (MMRp) colorectal cancer (CRC) has been refractory to single‐agent programmed cell death protein 1 (PD1) inhibitor therapy. Colon GVAX is an allogeneic, whole‐cell, granulocyte‐macrophage colony‐stimulating factor ‐secreting cellular immunotherapy that induces T‐cell immunity against tumor‐associated antigens and has previously been studied in combination with low‐dose cyclophosphamide (Cy) to inhibit regulatory T cells.

Methods

We conducted a single‐arm study of GVAX/Cy in combination with the PD1 inhibitor pembrolizumab in patients with advanced MMRp CRC. Patients received pembrolizumab plus Cy on day 1, GVAX on day 2, of a 21‐day cycle. The primary endpoint was the objective response rate by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Secondary objectives included safety, overall survival, progression‐free survival, changes in carcinoembryonic antigen (CEA) levels, and immune‐related correlates.

Results

Seventeen patients were enrolled. There were no objective responses, and the disease control rate was 18% by RECIST 1.1. The median progression‐free survival was 82 days (95% confidence interval [CI], 48‐97 days) and the median overall survival was 213 days (95% CI 179‐441 days). Biochemical responses (≥30% decline in CEA) were observed in 7/17 (41%) of patients. Grade ≥ 3 treatment‐related adverse events were observed in two patients (hemolytic anemia and corneal transplant rejection). Paired pre‐ and on‐treatment biopsy specimens showed increases in programmed death‐ligand 1 expression and tumor necrosis in a subset of patients.

Conclusions

GVAX/Cy plus pembrolizumab failed to meet its primary objective in MMRp CRC. Biochemical responses were observed in a subset of patients and have not previously been observed with pembrolizumab monotherapy in MMRp CRC, indicating that GVAX may modulate the antitumor immune response.

Lesion-Level Response Dynamics to Programmed Cell Death Protein (PD-1) Blockade

PURPOSE

Response to programmed cell death protein 1 (PD-1) blockade is often conceptualized as resulting from reinvigoration of tumor-infiltrating lymphocytes. However, recruited antitumor immunity from the periphery may also be an important contributor to response. A detailed assessment of the response dynamics of individual metastasis could provide insight to the systemic and local features that mediate response and resistance to immunotherapy.

MATERIALS AND METHODS

Patients with metastatic non-small-cell lung cancer (NSCLC) or mismatch repair deficiency (MMRD) carcinoma treated with PD-1 monotherapy were evaluated independently. Absolute and percent change of each target lesion were quantified at each computed tomography scan using RECIST. Patterns of progression were predefined as systemic or mixed and were correlated with clinical outcomes.

RESULTS

A total of 761 individual lesions from 214 patients with NSCLC and 290 lesions from 78 patients with MMRD carcinoma were examined. Individual target lesion responses aligned with best overall response of each patient (85% NSCLC and 93% MMRD lesions responded in patients with partial response/complete response). In responding patients, timing of response was uniform (73% NSCLC and 76% MMRD lesions responded synchronously), and deeper responses were associated with prolonged progression-free survival and overall survival. By contrast, at progression, mixed progression was common (45% of NSCLC and 53% of MMRD) and associated with improved survival compared with those who experienced systemic progression (NSCLC hazard ratio [HR], 0.58; P = .001; MMRD HR, 0.40; P = .07). Organ sites had differential responses, with lymph node and liver metastasis among the most and least responsive, respectively.

CONCLUSION

Temporal-spatial patterns of response across individual metastases tend to be uniform, favoring the role of peripheral, clonally directed antitumor immunity as a key mediator of response to PD-1 blockade. In contrast, progression is more heterogeneous, potentially revealing the clinical importance of local features and intertumoral heterogeneity.

Genetic diversity of tumors with mismatch repair deficiency influences anti-PD-1 immunotherapy response

Tumors with mismatch repair deficiency (MMR-d) are characterized by sequence alterations in microsatellites and can accumulate thousands of mutations. This high mutational burden renders tumors immunogenic and sensitive to programmed cell death-1 (PD-1) immune checkpoint inhibitors. Yet, despite their tumor immunogenicity, patients with MMR-deficient tumors experience highly variable responses, and roughly half are refractory to treatment. We present experimental and clinical evidence showing that the degree of microsatellite instability (MSI) and resultant mutational load, in part, underlies the variable response to PD-1 blockade immunotherapy in MMR-d human and mouse tumors. The extent of response is particularly associated with the accumulation of insertion-deletion (indel) mutational load. This study provides a rationale for the genome-wide characterization of MSI intensity and mutational load to better profile responses to anti-PD-1 immunotherapy across MMR-deficient human cancers.

Noninvasive Detection of Microsatellite Instability and High Tumor Mutation Burden in Cancer Patients Treated with PD-1 Blockade

PURPOSE

Microsatellite instability (MSI) and high tumor mutation burden (TMB-High) are promising pan-tumor biomarkers used to select patients for treatment with immune checkpoint blockade; however, real-time sequencing of unresectable or metastatic solid tumors is often challenging. We report a noninvasive approach for detection of MSI and TMB-High in the circulation of patients.

EXPERIMENTAL DESIGN

We developed an approach that utilized a hybrid-capture-based 98-kb pan-cancer gene panel, including targeted microsatellite regions. A multifactorial error correction method and a novel peak-finding algorithm were established to identify rare MSI frameshift alleles in cell-free DNA (cfDNA).

RESULTS

Through analysis of cfDNA derived from a combination of healthy donors and patients with metastatic cancer, the error correction and peak-finding approaches produced a specificity of >99% (n = 163) and sensitivities of 78% (n = 23) and 67% (n = 15), respectively, for MSI and TMB-High. For patients treated with PD-1 blockade, we demonstrated that MSI and TMB-High in pretreatment plasma predicted progression-free survival (hazard ratios: 0.21 and 0.23, P = 0.001 and 0.003, respectively). In addition, we analyzed cfDNA from longitudinally collected plasma samples obtained during therapy to identify patients who achieved durable response to PD-1 blockade.

CONCLUSIONS

These analyses demonstrate the feasibility of noninvasive pan-cancer screening and monitoring of patients who exhibit MSI or TMB-High and have a high likelihood of responding to immune checkpoint blockade.See related commentary by Wang and Ajani, p. 6887.

Intratumoral Adaptive Immunosuppression and Type 17 Immunity in Mismatch Repair Proficient Colorectal Tumors

PURPOSE

Approximately 10% of patients with mismatch repair-proficient (MMRp) colorectal cancer showed clinical benefit to anti-PD-1 monotherapy (NCT01876511). We sought to identify biomarkers that delineate patients with immunoreactive colorectal cancer and to explore new combinatorial immunotherapy strategies that can impact MMRp colorectal cancer.

EXPERIMENTAL DESIGN

We compared the expression of 44 selected immune-related genes in the primary colon tumor of 19 patients with metastatic colorectal cancer (mCRC) who responded (n = 13) versus those who did not (n = 6) to anti-PD-1 therapy (NCT01876511). We define a 10 gene-based immune signature that could distinguish responder from nonresponder. Resected colon specimens (n = 14) were used to validate the association of the predicted status (responder and nonresponder) with the immune-related gene expression, the phenotype, and the function of tumor-infiltrating lymphocytes freshly isolated from the same tumors.

RESULTS

Although both IL17Low and IL17High immunoreactive MMRp colorectal cancers are associated with intratumor correlates of adaptive immunosuppression (CD8/IFNγ and PD-L1/IDO1 colocalization), only IL17Low MMRp tumors (3/14) have a tumor immune microenvironment (TiME) that resembles the TiME in primary colon tumors of patients with mCRC responsive to anti-PD-1 treatment.

CONCLUSIONS

The detection of a preexisting antitumor immune response in MMRp colorectal cancer (immunoreactive MMRp colorectal cancer) is not sufficient to predict a clinical benefit to T-cell checkpoint inhibitors. Intratumoral IL17-mediated signaling may preclude responses to immunotherapy. Drugs targeting the IL17 signaling pathway are available in clinic, and their combination with T-cell checkpoint inhibitors could improve colorectal cancer immunotherapy.See related commentary by Willis et al., p. 5185.

Immunopathologic Stratification of Colorectal Cancer for Checkpoint Blockade Immunotherapy

Mismatch-repair deficiency in solid tumors predicts their response to PD-1 blockade. Based on this principle, pembrolizumab is approved as standard of care for patients with unresectable or metastatic microsatellite instability-high (MSI-H) cancer. Despite this success, a large majority of metastatic colorectal cancer patients are not MSI-H and do not benefit from checkpoint blockade treatment. Predictive biomarkers to develop personalized medicines and guide clinical trials are needed for these patients. We, therefore, asked whether immunohistologic stratification of metastatic colorectal cancer based on primary tumor PD-L1 expression associated with the presence or absence of extracellular mucin defines a subset of metastatic colorectal cancer patients who exhibit a preexisting antitumor immune response and who could potentially benefit from the checkpoint blockade. To address this, we studied 26 advanced metastatic colorectal cancer patients treated with pembrolizumab (NCT01876511). To stratify patients, incorporation of histopathologic characteristics (percentage of extracellular mucin) and PD-L1 expression at the invasive front were used to generate a composite score, the CPM (composite PD-L1 and mucin) score, which discriminated patients who exhibited clinical benefit (complete, partial, or stable disease) from those patients with progressive disease. When validated in larger cohorts, the CPM score in combination with MSI testing may guide immunotherapy interventions for colorectal cancer patient treatment.

Abstract 4491: Association of intratumoral immunologic profile with overall survival in metastatic pancreatic cancer patients treated with combination immunotherapy with or without PD-1 blockade

Background: Metastatic pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis with a 5-year survival rate of 8%. Single-agent immunotherapies fail to show clinical activity due to a complex tumor microenvironment (TME) and lack of effector T cells. We previously showed in a neoadjuvant clinical trial that an irradiated, granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting, allogeneic PDAC vaccine (GVAX) recruited T cells into tumor and upregulated the PD-1/PD-L1 pathway1. Here we describe the first clinical testing of GVAX prime given with attenuated listeria monocytogenes expressing mesothelin (CRS-207) boost alone or in combination with nivolumab to block PD-1 signaling in metastatic PDAC patients, and evaluated changes in the TME.

Experimental Design: 22 metastatic PDAC biopsy pairs were obtained at baseline and after 2 GVAX prime and 1 CRS-207 boost from 96 vaccinated patients. Nivolumab was administered with each vaccine in patients randomized to vaccine + nivolumab arm. Biopsies containing &gt;30% tumor cellularity were chosen for multiplex immunohistochemistry (IHC) to examine changes in immune cell subtypes and their signaling pathways in tumors. We did a comparative analysis looking at lymphoid and myeloid complexity, immune function, and PD-L1 status of patients with overall survival (OS) &lt;150 days [short OS, n=6], 150-300 days [middle OS, n=11], and &gt;300 days [long OS, n=5] or by treatment arm.

Results: Favorable OS correlated with low CD68+ myeloid cell and high lymphoid cell numbers, which was detected after prime-boost. Evaluation of the functional status of CD8+ T cells after prime-boost of patients with long OS revealed a 10.2% increase in EOMES+PD1- effector memory and 1.4% decrease in EOMES+PD1+ exhausted T cells. At baseline, fewer CSF1R+ tumor associated macrophages (TAMs), CD68+CD163+ and CD163- myeloid cells in tumors was associated with long OS. We analyzed nivolumab’s effect on the TME and found that tumors from nivolumab-treated patients displayed a decrease in CD68+ myeloid cells after prime-boost compared to baseline. Interestingly, CD163+ TAMs in tumors of nivolumab-treated patients expressed higher PD-L1 levels.

Conclusion: This study suggests that induction of lymphoid-inflamed expression profiles with less exhausted and more effector memory CD8+ T cells during treatment is associated with long OS independent of nivolumab treatment. Fewer TAMs in pre-treatment biopsies and a low myeloid: lymphoid cell ratio in post-immunotherapy tumor samples may be predictive of improved survival. Our findings also suggest that nivolumab induces PD-L1 expression on myeloid cells. Continual identification of key tissue-based biomarkers that correlate with OS may be useful for predicting therapeutic response.

1) Lutz E. (2014) Cancer Immunol Res. Jul;2(7):616-31.

Citation Format: Annie A. Wu, Takahiro Tsujikawa, Gina Choe, Teresa Beechwood, Lisa M. Coussens, Jennifer N. Durham, Elizabeth M. Jaffee, Dung T. Le. Association of intratumoral immunologic profile with overall survival in metastatic pancreatic cancer patients treated with combination immunotherapy with or without PD-1 blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4491.

Abstract CT207: Feasibility of neoadjuvant cabozantinib plus nivolumab followed by definitive resection for patients with locally advanced hepatocellular carcinoma: A Phase Ib trial (NCT03299946)

Long-term outcomes for patients with locally advanced hepatocellular carcinoma (HCC) are poor. Even if clear margins are obtained at the time of surgical resection, most patients with large tumors (&gt;5 cm) relapse due to micrometastatic disease. No therapy has demonstrated clinical benefit in the perioperative setting, underscoring the need for novel therapeutic strategies for resectable HCC. We hypothesize that neoadjuvant therapy resulting in downstaging and elimination of micrometastasis may increase the probability of successful surgical resection.

This ongoing open label, single arm Phase Ib trial (NCT03299946) aims to assess the feasibility of neoadjuvant cabozantinib plus nivolumab (CaboNivo) in patients with locally advanced HCC. Targets of cabozantinib include MET and VEGFR. Nivolumab is an immune checkpoint inhibitor targeting PD-1. This study will also allow us to test the hypothesis that cabozantinib primes the tumor microenvironment for anti-PD1 therapy and to study mechanisms of response and resistance to combination therapy. To our knowledge, this is the first neoadjuvant clinical trial of an immune checkpoint inhibitor and the first study of neoadjuvant combination therapy in HCC.

15 patients aged ≥ 18 with potentially resectable HCC that is at high risk of recurrence, ECOG ≤ 1, normal organ and marrow function, and adequate future liver remnant will be enrolled in the study. After 2 weeks of 40 mg daily cabozantinib monotherapy lead-in, patients will receive concurrent 240 mg nivolumab infusions once every 2 weeks for 4 doses. After 8 weeks of neoadjuvant therapy and restaging, patients eligible for resection will proceed to definitive surgical resection ≥ 28 days after the last dose of cabozantinib. Primary outcomes are feasibility and safety of neoadjuvant cabozantinib plus nivolumab. Secondary outcomes are percentage of patients obtaining an R0 resection, pathologic complete response and major pathologic response rates, objective response rate, median overall survival, and median disease free survival. Tumor biopsies from patients at baseline and after 2 weeks of cabozantinib lead-in as well as tumor tissue collected from surgical resection samples will be used to determine the effect of cabozantinib monotherapy and combination therapy with nivolumab on tumor-infiltrating lymphocytes, immune activation and suppression pathways, and cytokine/chemokine signaling.

Citation Format: Aleksandra Popovic, Elizabeth Sugar, Anna Ferguson, Bradley Wilt, Jennifer N. Durham, Ihab R. Kamel, Amy Kim, Benjamin Philosophe, Robert A. Anders, Elizabeth M. Jaffee, Daniel Laheru, Matthew J. Weiss, Mark Yarchoan. Feasibility of neoadjuvant cabozantinib plus nivolumab followed by definitive resection for patients with locally advanced hepatocellular carcinoma: A Phase Ib trial (NCT03299946) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT207.

Persistent mutant oncogene specific T cells in two patients benefitting from anti-PD-1

Background

Several predictive biomarkers are currently approved or are under investigation for the selection of patients for checkpoint blockade. Tumor PD-L1 expression is used for stratification of non-small cell lung (NSCLC) patients, with tumor mutational burden (TMB) also being explored with promising results, and mismatch-repair deficiency is approved for tumor site-agnostic disease. While tumors with high PD-L1 expression, high TMB, or mismatch repair deficiency respond well to checkpoint blockade, tumors with lower PD-L1 expression, lower mutational burdens, or mismatch repair proficiency respond much less frequently.

Case presentation

We studied two patients with unexpected responses to checkpoint blockade monotherapy: a patient with PD-L1-negative and low mutational burden NSCLC and one with mismatch repair proficient colorectal cancer (CRC), both of whom lack the biomarkers associated with response to checkpoint blockade, yet achieved durable clinical benefit. Both maintained T-cell responses in peripheral blood to oncogenic driver mutations – BRAF-N581I in the NSCLC and AKT1-E17K in the CRC – years after treatment initiation. Mutation-specific T cells were also found in the primary tumor and underwent dynamic perturbations in the periphery upon treatment.

Conclusions

These findings suggest that T cell responses to oncogenic driver mutations may be more prevalent than previously appreciated and could be harnessed in immunotherapeutic treatment, particularly for patients who lack the traditional biomarkers associated with response. Comprehensive studies are warranted to further delineate additional predictive biomarkers and populations of patients who may benefit from checkpoint blockade.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0492-x) contains supplementary material, which is available to authorized users.

A phase II study of GVAX colon vaccine with cyclophosphamide and pembrolizumab in patients with mismatch repair–proficient (MMR-p) advanced colorectal cancer

563

Background: Mismatch repair proficient (MMRp) colorectal cancer (CRC) is refractory to single-agent programmed cell death protein 1 (PD1) inhibitors. Cancer vaccines may prime the tumor microenvironment for anti-PD1 therapy. Colon GVAX is an allogeneic, whole-cell, GM-CSF-secreting vaccine that induces T-cell immunity against tumor-associated antigens. GVAX has previously been studied in combination with low-dose cyclophosphamide (Cy) to inhibit regulatory T cells. Methods: We conducted an open label, single-arm, phase 2 study of GVAX/Cy in combination with the PD1 inhibitor pembrolizumab in patients with MMRp CRC who had received at least two prior lines of therapy in the metastatic setting. Patients received pembrolizumab plus Cy on day 1, GVAX on day 2, of a 21 day cycle through 4 cycles, and were then continued on a maintenance regimen of pembolizumab every 3 weeks with cy/GVAX given every 12 weeks. Results: Seventeen patients were enrolled. There were no objective responses, and the disease control rate was 18% by RECIST and 29% by irRC. The median progression free survival was 2.7 months and the median overall survival was 7.0 months. Biochemical responses (≥30% decline in CEA) were observed in 7/17 (41%) of patients. Two patients (12%) had grade 3/4 adverse events that were attributed to study therapy. To test the hypothesis that the induction of a humoral response against CEA protein had resulted in the observed biochemical responses, we measured patient titers of anti-CEA antibodies. Anti-CEA antibody titers increased 13 of 13 patients (100%) with available paired pre- and on-treatment research blood samples, but the change in anti-CEA antibody titers were similar among CEA responders and non-responders. Multiplex immunohistochemistry performed on pre- and post- biopsy specimens will be reported at the conference. Conclusions: GVAX/Cy plus pembrolizumab is well tolerated in advanced MMRp CRC and resulted in CEA responses but not radiographic responses. PFS and OS compare favorably to historical controls in this small cohort. CEA responses were not observed with PD1 monotherapy in MMRp CRC, suggesting GVAX can modulate the antitumor immune response. Clinical trial information: NCT02981524.

T cell receptor repertoire features associated with survival in immunotherapy-treated pancreatic ductal adenocarcinoma

BACKGROUND

Immune checkpoint inhibitors provide significant clinical benefit to a subset of patients, but novel prognostic markers are needed to predict which patients will respond. This study was initiated to determine if features of patient T cell repertoires could provide insights into the mechanisms of immunotherapy, while also predicting outcomes.

METHODS

We examined T cell receptor (TCR) repertoires in peripheral blood of 25 metastatic pancreatic cancer patients treated with ipilimumab with or without GVAX (a pancreatic cancer vaccine), as well as peripheral blood and tumor biopsies from 32 patients treated with GVAX and mesothelin-expressing Listeria monocytogenes with or without nivolumab. Statistics from these repertoires were then tested for their association with clinical response and treatment group.

RESULTS

We demonstrate that, first, the majority of patients receiving these treatments experience a net diversification of their peripheral TCR repertoires. Second, patients receiving ipilimumab experienced larger changes in their repertoires, especially in combination with GVAX. Finally, both a low baseline clonality and a high number of expanded clones following treatment were associated with significantly longer survival in patients who received ipilimumab but not in patients receiving nivolumab.

CONCLUSIONS

We show that these therapies have measurably different effects on the peripheral repertoire, consistent with their mechanisms of action, and demonstrate the potential for TCR repertoire profiling to serve as a biomarker of clinical response in pancreatic cancer patients receiving immunotherapy. In addition, our results suggest testing sequential administration of anti-CTLA-4 and anti-PD-1 antibodies to achieve optimal therapeutic benefit.

TRIAL REGISTRATION

Samples used in this study were collected from the NCT00836407 and NCT02243371 clinical trials.

FUNDING

Research supported by a Stand Up To Cancer Lustgarten Foundation Pancreatic Cancer Convergence Dream Team Translational Research grant (SU2C-AACR-DT14-14). Stand Up To Cancer is a program of the Entertainment Industry Foundation administered by the American Association for Cancer Research (AACR). Additional clinical trial funding was provided by AACR-Pancreatic Cancer Action Network Research Acceleration Network grant (14-90-25-LE), NCI SPORE in GI Cancer (CA062924), Quick-Trials for Novel Cancer Therapies: Exploratory Grants (R21CA126058-01A2), and the US Food and Drug Administration (R01FD004819). Research collaboration and financial support were provided by Adaptive Biotechnologies.

Abstract 611: PD-1-based combination immunotherapy reinvigorates CD8+ T cells in metastatic pancreatic cancer patients with improved survival

Background: Metastatic pancreatic ductal adenocarcinoma (PDAC) is lethal with a 5-year survival rate of 2%. Single-agent immunotherapies fail to show clinical activity due to a complex tumor microenvironment (TME) and lack of effector T cells. We previously showed that an irradiated, granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting, allogeneic PDAC vaccine (GVAX) given as neoadjuvant recruited T cells into the tumor and upregulated the PD-1/PD-L1 pathway. Here we described the first testing of GVAX prime given with attenuated listeria monocytogenes expressing mesothelin (CRS-207) boost given with or without nivolumab to block PD-1 signaling and evaluated changes in the TME.

Experimental Design: Metastatic pancreatic tumor biopsies were obtained at baseline and after 2 GVAX prime and 1 CRS-207 boost from vaccinated patients. Nivolumab was administered with each vaccine in patients randomized to the nivolumab arm. Biopsies containing high density of tumor cells (&gt;30%) were chosen for multiplex immunohistochemistry (IHC) to examine changes in the immune cell subtypes and their signals in tumors. We did a comparative analysis looking at lymphoid, myeloid complexity, and immune functional status in the tumor microenvironment of patients who have overall survival &lt;6 months [short OS] and &gt;6 months [long OS].

Results: Post-immunotherapy changes in immune cell profiles correlated with overall survival. After prime-boost, expansion of CD8+ T cells was observed in the long OS group. Evaluation of the functional status of CD8+ T cells after prime-boost of short OS group showed an EOMES+PD1+ exhausted phenotype. In the myeloid compartment, low CSF1R+ tumor associated macrophages and CD68+ CD163+ and CD163- myeloid frequency in post-immunotherapy tumors were associated with less exhaustion of CD8+ T cells and long OS. The clinical trial is ongoing and blinded to study arm; thus, we have not yet analyzed whether nivolumab influences results. These data will be available at the time of abstract presentation.

Conclusion: This study provides evidence that longitudinal changes in immune cell complexity profiles can be correlated with overall survival. Increases in CD8+ early effectors and decreases in monocytes in baseline versus post-immunotherapy tumors are associated with improved survival. The exhausted CD8+ T cell profile in short OS patients may predict early responders versus nonresponders to vaccine containing immunotherapy.

Citation Format: Annie A. Wu, Takahiro Tsujikawa, Gina Choe, Teresa Beechwood, Lisa M. Coussens, Jennifer N. Durham, Elizabeth M. Jaffee, Dung T. Le. PD-1-based combination immunotherapy reinvigorates CD8+ T cells in metastatic pancreatic cancer patients with improved survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 611.

Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade

The genomes of cancers deficient in mismatch repair contain exceptionally high numbers of somatic mutations. In a proof-of-concept study, we previously showed that colorectal cancers with mismatch repair deficiency were sensitive to immune checkpoint blockade with antibodies to programmed death receptor-1 (PD-1). We have now expanded this study to evaluate the efficacy of PD-1 blockade in patients with advanced mismatch repair-deficient cancers across 12 different tumor types. Objective radiographic responses were observed in 53% of patients, and complete responses were achieved in 21% of patients. Responses were durable, with median progression-free survival and overall survival still not reached. Functional analysis in a responding patient demonstrated rapid in vivo expansion of neoantigen-specific T cell clones that were reactive to mutant neopeptides found in the tumor. These data support the hypothesis that the large proportion of mutant neoantigens in mismatch repair-deficient cancers make them sensitive to immune checkpoint blockade, regardless of the cancers' tissue of origin.

Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade

The genomes of cancers deficient in mismatch repair contain exceptionally high numbers of somatic mutations. In a proof-of-concept study, we previously showed that colorectal cancers with mismatch repair deficiency were sensitive to immune checkpoint blockade with antibodies to programmed death receptor-1 (PD-1). We have now expanded this study to evaluate the efficacy of PD-1 blockade in patients with advanced mismatch repair-deficient cancers across 12 different tumor types. Objective radiographic responses were observed in 53% of patients, and complete responses were achieved in 21% of patients. Responses were durable, with median progression-free survival and overall survival still not reached. Functional analysis in a responding patient demonstrated rapid in vivo expansion of neoantigen-specific T cell clones that were reactive to mutant neopeptides found in the tumor. These data support the hypothesis that the large proportion of mutant neoantigens in mismatch repair-deficient cancers make them sensitive to immune checkpoint blockade, regardless of the cancers' tissue of origin.

Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade

Colon cancers with loss-of-function mutations in the mismatch repair (MMR) pathway have favorable responses to PD-1 blockade immunotherapy. In a phase 2 clinical trial, Le et al. showed that treatment success is not just limited to colon cancer (see the Perspective by Goswami and Sharma). They found that a wide range of different cancer types with MMR deficiency also responded to PD-1 blockade. The trial included some patients with pancreatic cancer, which is one of the deadliest forms of cancer. The clinical trial is still ongoing, and around 20% of patients have so far achieved a complete response. MMR deficiency appears to be a biomarker for predicting successful treatment outcomes for several solid tumors and indicates a new therapeutic option for patients harboring MMR-deficient cancers.

Science , this issue p. 409 ; see also p. 358

Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade

The genomes of cancers deficient in mismatch repair contain exceptionally high numbers of somatic mutations. In a proof-of-concept study, we previously showed that colorectal cancers with mismatch repair deficiency were sensitive to immune checkpoint blockade with antibodies to programmed death receptor-1 (PD-1). We have now expanded this study to evaluate the efficacy of PD-1 blockade in patients with advanced mismatch repair-deficient cancers across 12 different tumor types. Objective radiographic responses were observed in 53% of patients, and complete responses were achieved in 21% of patients. Responses were durable, with median progression-free survival and overall survival still not reached. Functional analysis in a responding patient demonstrated rapid in vivo expansion of neoantigen-specific T cell clones that were reactive to mutant neopeptides found in the tumor. These data support the hypothesis that the large proportion of mutant neoantigens in mismatch repair-deficient cancers make them sensitive to immune checkpoint blockade, regardless of the cancers' tissue of origin.

Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade

Colon cancers with loss-of-function mutations in the mismatch repair (MMR) pathway have favorable responses to PD-1 blockade immunotherapy. In a phase 2 clinical trial, Le et al. showed that treatment success is not just limited to colon cancer (see the Perspective by Goswami and Sharma). They found that a wide range of different cancer types with MMR deficiency also responded to PD-1 blockade. The trial included some patients with pancreatic cancer, which is one of the deadliest forms of cancer. The clinical trial is still ongoing, and around 20% of patients have so far achieved a complete response. MMR deficiency appears to be a biomarker for predicting successful treatment outcomes for several solid tumors and indicates a new therapeutic option for patients harboring MMR-deficient cancers.

Science , this issue p. 409 ; see also p. 358

Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade

Colon cancers with loss-of-function mutations in the mismatch repair (MMR) pathway have favorable responses to PD-1 blockade immunotherapy. In a phase 2 clinical trial, Le et al. showed that treatment success is not just limited to colon cancer (see the Perspective by Goswami and Sharma). They found that a wide range of different cancer types with MMR deficiency also responded to PD-1 blockade. The trial included some patients with pancreatic cancer, which is one of the deadliest forms of cancer. The clinical trial is still ongoing, and around 20% of patients have so far achieved a complete response. MMR deficiency appears to be a biomarker for predicting successful treatment outcomes for several solid tumors and indicates a new therapeutic option for patients harboring MMR-deficient cancers.

Science , this issue p. 409 ; see also p. 358

Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade

Colon cancers with loss-of-function mutations in the mismatch repair (MMR) pathway have favorable responses to PD-1 blockade immunotherapy. In a phase 2 clinical trial, Le et al. showed that treatment success is not just limited to colon cancer (see the Perspective by Goswami and Sharma). They found that a wide range of different cancer types with MMR deficiency also responded to PD-1 blockade. The trial included some patients with pancreatic cancer, which is one of the deadliest forms of cancer. The clinical trial is still ongoing, and around 20% of patients have so far achieved a complete response. MMR deficiency appears to be a biomarker for predicting successful treatment outcomes for several solid tumors and indicates a new therapeutic option for patients harboring MMR-deficient cancers.

Science , this issue p. 409 ; see also p. 358

Neoadjuvant randomized trial of degarelix (Deg) ± cyclophosphamide/GVAX (Cy/GVAX) in men with high-risk prostate cancer (PCa) undergoing radical prostatectomy (RP)

5077

Background: GVAX-Prostate is a GM-CSF–secreting allogeneic cellular vaccine, whose immunogenicity may be enhanced by androgen ablation as well as low-dose Cy. We conducted a neoadjuvant immunologic study comparing Deg vs. Cy/GVAX→Deg. Methods: Men with high-risk PCa (T1c–3b N0 M0, Gleason 7–10) were randomized 1:1 to Deg(240 mg SQ) vs. Cy(200 mg/m2 IV)/GVAX(2.5×108 PC3 cells, 1.6×108 LNCaP cells) given 2 wk before Deg; all pts then had RP 2 wk after Deg. CD8+ T cell and Treg densities in the primary tumor were quantified by IHC (cells/mm2). Clinical endpoints were time-to-PSA-relapse, time-to-next-therapy, and time-to-metastasis. The study was powered (α = 0.05, β = 0.18) to show a 2-fold increase in mean CD8+ density with Cy/GVAX→Deg (Arm B) vs. Deg (Arm A). Results: 28 men were enrolled (Arm A = 15, Arm B = 13). A concurrent control group (N = 20) who did not receive neoadjuvant therapy provided untreated RP tumor samples. Baseline variables were balanced across study arms: 64% had Gleason ≥8, 56% were pT3b, 18% were pN1. There were nonsignificant increases in CD8+ and Treg densities in Arm B vs. A, and statistically significant increases in CD8+ and Treg densities in both arms (A, B) compared to group C (TABLE). CD8+ and Treg densities were strongly correlated. Outcomes were numerically better in Arm B vs A with respect to time-to-PSA-relapse (HR 0.42, 95%CI 0.13–1.38, P= 0.15) and time-to-next-therapy (HR 0.43, 95%CI 0.13–1.39, P= 0.16), although not statistically significant. Conclusions: Intratumoral immune infiltrates were marginally augmented by Cy/GVAX→Deg vs. Deg alone, while CD8+ and Treg densities were significantly greater in both study arms vs. control, supporting the immunogenic effects of androgen ablation. CD8+ / Treg ratios were remarkably consistent across groups. Clinical trial information: NCT01696877. [Table: see text]

Phase II study of GM-CSF secreting allogeneic pancreatic cancer vaccine (GVAX) with PD-1 blockade antibody and stereotactic body radiation therapy (SBRT) for locally advanced pancreas cancer (LAPC)

TPS4154

Background: Optimal treatment strategy beyond systemic chemotherapy for LAPC remains undefined. SBRT improves local control, but distant metastasis free survival (DMFS) is only 7.7 months. Checkpoint inhibitors are poor monotherapies in pancreas cancer, but may be primed by SBRT via absocopal effect and GVAX, which induces novel lymphoid infiltrates and increased effector T-cells in tumor microenvironment. Methods: This is a single-arm, single-institution, open-label study for pts with LAPC. Eligibility: surgically unresectable LAPC, predominant adenocarcinoma at diagnosis, with ECOG 0-1, who remain metastases free after 4-8 cycles of FOLFIRINOX or gemcitabine/abraxane based-chemotherapy. Exclusion: those off chemotherapy > 49 days prior to study treatment, prior immunotherapy, active immunosuppressive use, autoimmune disease, HIV, HBV, or HCV infection, and non-oncology vaccines within 28 days of study treatment. Pts receive cyclophosphamide (200mg/m2 IV) and pembrolizumab (200mg IV) on day 1, followed by GVAX (six intradermal injections) on day 2 every three weeks for two cycles, with cycle 2 initiating concurrently with five days of SBRT. If non-metastatic, pts undergo surgical resection, nano-knife, or EUS guided biopsy (if non-surgical). Pts receive two further cycles of chemotherapy, and if remain free of metastases, receive q3 week cyclophosphamide, pembrolizumab, and GVAX for six cycles, then are monitored for two years. The primary endpoint is DMFS. Secondary endpoints include overall survival, surgical resectability, pathologic response, quality of life, and toxicity. Exploratory objectives of peripheral antigen specific t-cell responses, and changes in immune parameters of tumor microenvironment. 11 of 54 pts have been enrolled since July 2016. Clinical trial information: NCT02648282.