A Pilot Feasibility Study of Yttrium-90 Liver Radioembolization Followed by Durvalumab and Tremelimumab in Patients with Microsatellite Stable Colorectal Cancer Liver Metastases

Redefining the battle against colorectal cancer: a comprehensive review of emerging immunotherapies and their clinical efficacy

Colorectal cancer (CRC) is the third most common cancer globally and presents a significant challenge owing to its high mortality rate and the limitations of traditional treatment options such as surgery, radiotherapy, and chemotherapy. While these treatments are foundational, they are often poorly effective owing to tumor resistance. Immunotherapy is a groundbreaking alternative that has recently emerged and offers new hope for success by exploiting the body's own immune system. This article aims to provide an extensive review of clinical trials evaluating the efficacy of various immunotherapies, including CRC vaccines, chimeric antigen receptor T-cell therapies, and immune checkpoint inhibitors. We also discuss combining CRC vaccines with monoclonal antibodies, delve into preclinical studies of novel cancer vaccines, and assess the impact of these treatment methods on patient outcomes. This review seeks to provide a deeper understanding of the current state of CRC treatment by evaluating innovative treatments and their potential to redefine the prognosis of patients with CRC.

PD-1 and PD-L1 inhibitors in cold colorectal cancer: challenges and strategies

Colorectal cancer (CRC) is the second most common cause of cancer mortality, with mismatch repair proficient (pMMR) and/or microsatellite stable (MSS) CRC making up more than 80% of metastatic CRC. Programmed death-ligand 1 (PD-L1) and programmed death 1 (PD-1) immune checkpoint inhibitors (ICIs) are approved as monotherapy in many cancers including a subset of advanced or metastatic colorectal cancer (CRC) with deficiency in mismatch repair (dMMR) and/or high microsatellite instability (MSI-H). However, proficient mismatch repair and microsatellite stable (pMMR/MSS) cold CRCs have not shown clinical response to ICIs alone. To potentiate the anti-tumor response of PD-L1/PD-1 inhibitors in patients with MSS cold cancer, combination strategies currently being investigated include dual ICI, and PD-L1/PD-1 inhibitors in combination with chemotherapy, radiotherapy, vascular endothelial growth factor (VEGF) /VEGF receptor (VEGFR) inhibitors, mitogen-activated protein kinase (MEK) inhibitors, and signal transducer and activation of transcription 3 (STAT3) inhibitors. This paper will review the mechanisms of PD-1/PD-L1 ICI resistance in pMMR/MSS CRC and potential combination strategies to overcome this resistance, summarize the published clinical experience with different combination therapies, and make recommendations for future avenues of research.

Liver-Directed Therapy Combined with Systemic Therapy: Current Status and Future Directions

In the past several decades, major advances in both systemic and locoregional therapies have been made for many cancer patients. This has led to modern cancer treatment algorithms frequently calling for active interventions by multiple subspecialists at the same time. One of the areas where this can be clearly seen is the concomitant use of locoregional and systemic therapies in patients with primary or secondary cancers of the liver. These combined algorithms have gained favor over the last decade and are largely focused on the allure of the combined ability to control systemic disease while at the same time addressing refractory/resistant clonal populations. While the general concept has gained favor and is likely to only increase in popularity with the continued establishment of viable immunotherapy treatments, for many patients questions remain. Lingering concerns over the increase in toxicity when combining treatment methods, patient selection, and sequencing remain for multiple cancer patient populations. While further work remains, some of these questions have been addressed in the literature. This article reviews the available data on three commonly treated primary and secondary cancers of the liver, namely, hepatocellular carcinoma, cholangiocarcinoma, and metastatic colorectal cancer. Furthermore, strengths and weaknesses are reviewed and future directions are discussed.

Targeting Liver Metastases to Potentiate Immunotherapy in MS-Stable Colorectal Cancer-A Review of the Literature

Immunotherapy has revolutionized the treatment of several cancers, including melanoma and lung cancer. However, for colorectal cancer, it is ineffective for 95% of patients with microsatellite-stable disease. Recent evidence suggests that the liver's immune microenvironment plays a pivotal role in limiting the effectiveness of immunotherapy. There is also evidence to show that targeting liver metastases with locoregional therapies, such as surgery or irradiation, could potentiate immunotherapy for these patients. This review presents evidence from preclinical studies regarding the underlying mechanisms and from clinical studies that support this approach. Furthermore, we outline potential directions for future clinical trials. This innovative strategy could potentially establish immunotherapy as an effective treatment for MS-stable colorectal cancer patients, which are currently considered resistant.

Efficacy and safety of immune checkpoint inhibitors in Proficient Mismatch Repair (pMMR)/ Non-Microsatellite Instability-High (non-MSI-H) metastatic colorectal cancer: a study based on 39 cohorts incorporating 1723 patients

PURPOSE

This study was designed to investigate the efficacy and safety of immune checkpoint inhibitors (ICIs)-based therapy in proficient mismatch repair (pMMR)/non-microsatellite instability-high (non-MSI-H) metastatic colorectal cancer (mCRC).

METHODS

Electronic databases were screened to identify relevant trials. The primary endpoints were pooled objective response rate (ORR) and disease control rate (DCR). Stratified analysis was accomplished on ICIs-based regimens, treatment lines and RAS status.

RESULTS

Totally, 1723 mCRC patients from 39 cohorts were included. The pooled ORR, DCR, 12-month overall survival (OS) rate and 6-month progression-free survival (PFS) rate of ICIs-based therapy in pMMR/non-MSI-H mCRC were 8.5% (95% CI: 4.4%-13.5%), 48.2% (95% CI: 37.8%-58.6%), 52.3% (95% CI: 46.4%-58.1%) and 32.8% (95% CI: 23.5%-42.7%) respectively. As a whole, no significantly differences were shown between ICIs-based and non-ICIs-based therapy for pMMR/non-MSI-H mCRC in terms of both PFS (HR = 1.0, 95% CI: 0.9-1.1, P = 0.91) and OS (HR = 1.0, 95% CI: 0.9-1.2, P = 0.51). It was worth noting that the addition of ICIs to anti-vascular endothelial growth factor (VEGF) agent plus chemotherapy displayed excellent efficacy in pMMR/non-MSI-H mCRC (ORR = 42.4%, 95% CI: 10.0%-78.6%; DCR = 92.0%, 95% CI: 68.3%-100.0%; 12-month OS rate = 71.4%, 95% CI: 50.0%-89.1%; 6-month PFS rate = 55.2%, 95% CI: 24.8%-83.8%; and PFS (compared with non-ICIs-based therapy): HR = 0.9, 95% CI: 0.8-1.0, P = 0.02), especially served as first-line therapy (ORR = 74.2%, 95% CI: 61.4%-85.4%; DCR = 98.7%, 95% CI: 92.0%-100.0%); and without additional treatment related adverse events (TRAEs) were observed.

CONCLUSIONS

ICIs-based combination therapy, especially the addition of ICIs to first-line anti-VEGF agent plus chemotherapy, is promising in pMMR/non-MSI-H mCRC with good efficacy and controllable toxicity.

Immune checkpoint inhibition: a future guided by radiology

The limitation of the function of antitumour immune cells is a common hallmark of cancers that enables their survival. As such, the potential of immune checkpoint inhibition (ICI) acts as a paradigm shift in the treatment of a range of cancers but has not yet been fully capitalised. Combining minimally and non-invasive locoregional therapies offered by radiologists with ICI is now an active field of research with the aim of furthering therapeutic capabilities in medical oncology. In parallel to this impending advancement, the "imaging toolbox" available to radiologists is also growing, enabling more refined tumour characterisation as well as greater accuracy in evaluating responses to therapy. Options range from metabolite labelling to cellular localisation to immune checkpoint screening. It is foreseeable that these novel imaging techniques will be integrated into personalised treatment algorithms. This growth in the field must include updating the current standardised imaging criteria to ensure they are fit for purpose. Such criteria is crucial to both appropriately guide clinical decision-making regarding next steps of treatment, but also provide reliable prognosis. Quantitative approaches to these novel imaging techniques are also already being investigated to further optimise personalised therapeutic decision-making. The therapeutic potential of specific ICIs and locoregional therapies could be determined before administration thus limiting unnecessary side-effects whilst maintaining efficacy. Several radiological aspects of oncological care are advancing simultaneously. Therefore, it is essential that each development is assessed for clinical use and optimised to ensure the best treatment decisions are being offered to the patient. In this review, we discuss state of the art advances in novel functional imaging techniques in the field of immuno-oncology both pre-clinically and clinically.

Radiopharmaceuticals heat anti-tumor immunity

Radiopharmaceutical therapy (RPT) has proven to be an effective cancer treatment with minimal toxicity. With several RPT agents approved by FDA, the remarkable potential of this therapy is now being recognized, and the anti-tumor immunity induced by RPT is beginning to be noticed. This review evaluates the potential of RPT for immune activation, including promoting the release of danger associated-molecular pattern molecules that recruit inflammatory cells into the tumor microenvironment, and activating antigen-presenting cells and cytotoxic T cells. We also discuss the progress of combining RPT with immunotherapy to increase efficacy.

RESIRT: A Phase 1 Study of Selective Internal Radiation Therapy Using Yttrium-90 Resin Microspheres in Patients With Primary Renal Cell Carcinoma

INTRODUCTION

Selective internal radiation therapy (SIRT) is a potential treatment of primary renal cell carcinoma (RCC) deemed unsuitable for conventional therapy. RESIRT is the first-in-human study to evaluate safety and feasibility of SIRT for primary RCC.

PATIENTS AND METHODS

Patients with RCC, unsuitable for, or who declined conventional therapy, were eligible. A single transfemoral micro-catheter administration of yttrium-90 (Y-90) resin microspheres (SIR-Spheres) was delivered super selectively via the renal artery to the tumour at intended radiation doses of 75, 100, 150, 200, 300 Gy and a final cohort with a procedural endpoint of "imminent stasis," in a dose-escalation design. Post-SIRT follow-up was 12 months. Study endpoints included safety and toxicity 30-days and 12-months post-SIRT and tumour response (RECIST v1.1).

RESULTS

In total, 21 patients were enrolled, mean (SD) age was 75 (9.3) years, WHO performance status was 0 in 81%, 12 (57%) had stage 3 chronic kidney disease, and 7 (33%) had prior contralateral nephrectomy. Overall, 71% of patients completed 12 months of follow-up. Intended doses were delivered without any dose-limiting toxicity. Seventeen out of 21 (81%) patients experienced an adverse event (AE) from any cause within 30 days post-SIRT; all SIRT-related AEs were grade 1 to 2. Best overall tumour responses were partial response 1/21 (4.8%), stable disease 19/21 (90.5%) and progressive disease 1/21 (4.8%).

CONCLUSION

This study demonstrated good tolerability of SIRT at all dose levels including "imminent stasis" in treating primary tumours in RCC patients otherwise unsuitable for conventional therapy. SIRT with Y-90 resin microspheres may be a feasible treatment option for RCC.

IFNγ signaling integrity in colorectal cancer immunity and immunotherapy

The majority of colorectal cancer patients are not responsive to immune checkpoint blockade (ICB). The interferon gamma (IFNγ) signaling pathway drives spontaneous and ICB-induced antitumor immunity. In this review, we summarize recent advances in the epigenetic, genetic, and functional integrity of the IFNγ signaling pathway in the colorectal cancer microenvironment and its immunological relevance in the therapeutic efficacy of and resistance to ICB. Moreover, we discuss how to target IFNγ signaling to inform novel clinical trials to treat patients with colorectal cancer.

A systematic review of phase II trials exploring anti-PD-1/PD-L1 combinations in patients with solid tumors

BACKGROUND

A high number of combinations of PD-1/PD-L1 inhibitors with other anti-cancer therapies are in clinical development. The usefulness of phase II trials in evaluating their efficacy and safety is unclear.

MATERIALS AND METHODS

We performed a systematic search on PubMed and Cochrane Library for phase II trials of PD-1/PD-L1 inhibitors in combination with other anti-cancer therapies (systemic therapy and/or radiotherapy) published between January 1st 2018 and December 31st 2020. Study design, primary endpoint and main outcomes were registered for each paper.

RESULTS

119 articles reporting on 65 regimens were included in our analysis. Backbone agents were more frequently PD-1 inhibitors (pembrolizumab = 47, nivolumab = 41, camrelizumab = 3) followed by anti-PD-L1 (durvalumab = 19, atezolizumab = 6, avelumab = 3). Therapeutic partners were other immunotherapeutic agents (n = 46), targeted therapies (n = 40), chemotherapy (n = 22) or radiotherapy (n = 11). The majority of articles reported on single-arm trials (n = 87, 73%) and response rate was the most frequent primary endpoint (n = 69, 58%). Objective responses, registered in 109 (92%) articles, ranged between 0% and 91%. The incidence of grade 3 or higher treatment-related adverse events, clearly reported in 97 (82%) articles, spanned from 0 to 100%. Five combinations received regulatory approval by Food and Drug Administration or European Medicine Agency for 9 different indications, based on the results of a phase II trial (n = 3) or on a confirmatory phase III trial (n = 6).

CONCLUSIONS

The landscape of phase II trials evaluating PD-1/PD-L1 inhibitors with other anticancer therapies is heterogeneous. Combinations of two immunotherapeutic agents have been the most investigated. Only a minority of indications (8%) granted regulatory approval.

Clinical Response to Immunotherapy Targeting Programmed Cell Death Receptor 1/Programmed Cell Death Ligand 1 in Patients With Treatment-Resistant Microsatellite Stable Colorectal Cancer With and Without Liver Metastases

IMPORTANCE

Microsatellite stable (MSS) metastatic colorectal cancer has been historically characterized as resistant to immunotherapy. Recent studies have demonstrated limited clinical activity of programmed cell death receptor 1/programmed death ligand 1 (PD-1/PD-L1) targeting in MSS metastatic colorectal cancer. The association of metastatic disease in the liver with treatment response has not been fully investigated.

OBJECTIVE

To investigate the association of liver metastases with response to PD-1/PD-L1-targeting therapy in MSS metastatic colorectal cancer.

DESIGN, SETTING, AND PARTICIPANTS

This single-center retrospective cohort study evaluated clinical responses to PD-1- or PD-L1-targeting therapy, with or without other investigational agents, in patients with MSS metastatic colorectal cancer and disease progression after standard of care therapy from January 1, 2014, to December 31, 2020.

MAIN OUTCOMES AND MEASURES

Objective response rate (ORR) and progression-free survival (PFS), measured from initiation of PD-1/PD-L1-targeting therapy.

RESULTS

Ninety-five patients with MSS metastatic colorectal cancer were identified (54 men [56.8%]; median age, 55 [interquartile range (IQR), 49-64] years). The overall ORR was 8.4% (8 of 95 patients). Eight of 41 patients without liver metastases achieved an ORR of 19.5%, and no response was observed in 54 patients with liver metastases. The disease control rate was 58.5% (24 of 41) in patients without liver metastasis and 1.9% (1 of 54) in patients with liver metastasis. Patients without liver metastases at the time of PD-1/PD-L1-targeting treatment had a superior median PFS compared with patients with liver metastases (4.0 [IQR, 2.0-7.5] vs 1.5 [IQR, 1.0-2.0] months; P < .001). In addition, median PFS was 5.5 (IQR, 2.0-11.5) months for patients without any prior or current liver involvement at the time of PD-1/PD-L1-targeting treatment initiation. Using a multivariate Cox regression model correcting for Eastern Cooperative Oncology Group status, primary tumor location, RAS and BRAF status, tumor mutation burden, and metastatic sites, liver metastases was the variable with the most significant association with faster progression after PD-1/PD-L1 treatment inhibition (hazard ratio, 7.00; 95% CI, 3.18-15.42; P < .001).

CONCLUSIONS AND RELEVANCE

Findings of this cohort study suggest that patients with MSS metastatic colorectal cancer and without liver metastases may derive clinical benefits from checkpoint inhibitors, whereas the presence of liver metastases was associated with resistance. Further prospective studies are needed to investigate PD-1/PD-L1 inhibitors in patients with MSS metastatic colorectal cancer without liver metastases.

Targeting MSS colorectal cancer with immunotherapy: are we turning the corner?

INTRODUCTION

Immunotherapy with checkpoint inhibition has shown potent antitumor activity in patients with microsatellite instability (MSI) metastatic cancer. Microsatellite stable (MSS) colorectal cancer has long been considered resistant to immunotherapy.

AREAS COVERED

In this review, we provide an overview of current progress on strategies to overcome the resistance to immunotherapy in MSS colorectal cancer.

EXPERT OPINION

Emerging evidence suggest that combination of immune modulators such as regorafenib may improve the responsiveness of MSS colorectal cancer to checkpoint blockade. In addition, signs of clinical activity have also been observed in other combination strategies, such as the combination of checkpoint blockade with Stat3 inhibitor, or bispecific T-cell engagers. Nevertheless, predictive biomarkers that can identify patients who may benefit from immunotherapy are key for its implementation in clinical setting. Metastatic disease sites may predict for the response or resistance to checkpoint blockade, with liver metastases emerging as a strong predictive biomarker of lack of benefit from PD-1 targeting, even with combination therapies. Additional efforts are required to study the mechanism of resistance and to develop novel therapeutic strategies to overcome immune resistance.

ABBREVIATIONS

CEA: carcinoembryonic antigen; CR: complete response; CTLA-4: cytotoxic T-lymphocyte-associated protein 4; DCR: disease control rate; MSI-H: microsatellite instability-high; MSS: Microsatellite stable (MSS); OS: overall survival; PD-1: programmed cell death protein 1; PD-L1: programmed death-ligand receptor 1; PR: partial response; PFS: progression-free survival; SD: stable disease; TMB: tumor mutation burden; VEGFR: vascular endothelial growth factor receptor.

Pilot Clinical Trial of Perioperative Durvalumab and Tremelimumab in the Treatment of Resectable Colorectal Cancer Liver Metastases

PURPOSE

Despite the prognostic importance of immune infiltrate in colorectal cancer, immunotherapy has demonstrated limited clinical activity in refractory metastatic proficient mismatch-repair (pMMR) colorectal cancer. This study explores combining anti-CTLA-4 and an anti-PD-L1 therapy in the preoperative management of resectable colorectal cancer liver metastases with the intent to improve immune responses in this disease setting.

PATIENTS AND METHODS

Patients with resectable colorectal cancer liver-only metastases received one dose of tremelimumab and durvalumab preoperatively followed by single-agent durvalumab postoperatively. Primary objectives were to determine feasibility and safety.

RESULTS

A total of 24 patients were enrolled between November 2016 and November 2019. Twenty-three patients received treatment [21 pMMR and 2 deficient mismatch-repair (dMMR)] and subsequently 17 (74%; 95% CI: 53%-88%) underwent surgical resection. Grade 3/4 treatment-related immune toxicity and postoperative grade 3/4 toxicity were seen in 5/23 (22%; 95% CI: 10%-44%) and 2/17 (12%; 95% CI: 2%-38%) patients. The median relapse-free survival (RFS) was 9.7 (95% CI: 8.1-17.8) months, and overall survival was 24.5 (95% CI: 16.5-28.4) months. Four patients demonstrated complete pathologic response, two dMMR patients and two POLE mutation patients. Pre- and post-tumor tissue analysis by flow cytometry, immunofluorescence, and RNA sequencing revealed similar levels of T-cell infiltration, but did demonstrate evidence of CD8⁺ and CD4⁺ activation posttreatment. An increase in B-cell transcriptome signature and B-cell density was present in posttreatment samples from patients with prolonged RFS.

CONCLUSIONS

This study demonstrates the safety of neoadjuvant combination tremelimumab and durvalumab prior to colorectal cancer liver resection. Evidence for T- and B-cell activation following this therapy was seen in pMMR metastatic colorectal cancer.

Emerging Role of Immunotherapy for Colorectal Cancer with Liver Metastasis

Colorectal cancer (CRC) is the third most common malignant tumor in the world and the second leading cause of cancer-related deaths, with the liver as the most common site of distant metastasis. The prognosis of CRC with liver metastasis is poor, and most patients cannot undergo surgery. In addition, conventional antitumor approaches such as chemotherapy, radiotherapy, targeted therapy, and surgery result in unsatisfactory outcomes. In recent years, immunotherapy has shown good prospects in the treatment of assorted tumors by enhancing the host's antitumor immune function, and it may become a new effective treatment for liver metastasis of CRC. However, challenges remain in applying immunotherapy to CRC with liver metastasis. This review examines how the microenvironment and immunosuppressive landscape of the liver favor tumor progression. It also highlights the latest research advances in immunotherapy for colorectal liver metastasis and identifies immunotherapy as a treatment regimen with a promising future in clinical applications.