Management of metastatic endometrial cancer: physicians' choices beyond the first line after approval of checkpoint inhibitors.

Introduction: Endometrial cancer (EC) represents 3.4% of all newly diagnosed cancer cases and is responsible for 2.1% of all cancer-related deaths. Approximately 10%-15% of women with EC are diagnosed with advanced-stage disease, resulting in a reported 5-year survival rate of only 17% for those with distant metastases. A better understanding of its molecular features has ushered in a new era of immunotherapy for the treatment of EC, allowing for alternative therapeutic approaches, even in cases of advanced disease. Methods: We administered a multi-choice online survey for Multicenter Italian Trials in Ovarian cancer and gynecologic malignancies (MITO) members. The questionnaire was available for 2 months, starting in October 2022. Our objective was to evaluate the current attitude of incorporating molecular characterization of EC into routine clinical practice, appraise the implementation of newly available therapies, and compare the outcomes with the previous survey conducted in April-May 2021 to ascertain the actual changes that have transpired during this recent time period. Results: The availability of molecular classification in Italian centers has changed in 1 year. Seventy-five percent of centers performed the molecular classification compared with 55.6% of the previous survey. Although this percentage has increased, only 18% performed all the tests. Significant changes have occurred in the administration of new treatments in EC patients in MITO centers. In 2022, 82.1% of the centers administrated dostarlimab in recurrent or advanced MMR-deficient (dMMR) EC experiencing disease progression after platinum-based chemotherapy regimens, compared to only 24.4% in 2021. In 2022, 85.7% of the centers already administrated the pembrolizumab plus lenvatinib combination as a second-line therapy for MMR-proficient (pMMR) patients with advanced or recurrent EC who had progressed from first-line platinum-based therapy. Conclusion: Both the therapeutic and diagnostic scenarios have changed over the last couple of years in MITO centers, with an increased prescription of immune checkpoint inhibitors and use of the molecular classification.

Assessing the safety and activity of cabozantinib combined with lanreotide in gastroenteropancreatic and thoracic neuroendocrine tumors: rationale and protocol of the phase II LOLA trial.

BACKGROUND: Well-differentiated (WD) neuroendocrine tumors (NETs) are a group of rare neoplasms with limited therapeutic options. Cabozantinib is an inhibitor of multiple tyrosine kinases with a pivotal role in NET pathogenesis, including c-MET and Vascular Endothelial Growth Factor Receptor 2 (VEGFR2). LOLA is the first prospective phase II trial aiming to assess the safety and activity of cabozantinib combined with lanreotide in WD NETs of gastroenteropancreatic (GEP), thoracic and of unknown origin. METHODS: This is a multicenter, open-label, double-cohort, non comparative, non-randomized, three-stage phase II trial. Eligible patients have to meet the following inclusion criteria: diagnosis of advanced or metastatic, progressive, non-functioning WD thoracic NETs, GEP-NETs or NETs of unknown origin with Ki67 ≥ 10%; positive 68 Ga-PET uptake or somatostatin receptor 2 immunohistochemical (IHC) stain; maximum 1 prior systemic regimen for metastatic disease. Two cohorts will be considered: pNETs and carcinoids (typical or atypical lung and thymus NETs, gastro-intestinal NETs or NETs of unknown origin). In stage I, the primary objective is to find the optimal dose of cabozantinib in combination with lanreotide and to evaluate the safety of the combination (percentage of patients experiencing grade 3-5 toxicities according to NCI-CTCAE version 5.0). Starting dose of cabozantinib is 60 mg/day continuously, plus lanreotide 120 mg every 28 days. In stage II and III, co-primary endpoints are safety and overall response rate (ORR) according to RECIST version 1.1. The uninteresting antitumor activity is fixed in ORR ≤ 5%. Secondary endpoints are progression-free survival and overall survival. Exploratory objectives include the assessment of c-MET, AXL and VEGFR2 IHC expression, to identify predictive or prognostic tissue biomarkers. Enrolment started in July 2020, with an expected trial duration of 42 months comprehensive of accrual, treatment and follow-up. Considering a drop-out rate of 5%, the maximum number of enrolled patients will be 69. DISCUSSION: Supported by a solid rationale, the trial has the potential to generate milestone data about the synergistic effects of cabozantinib plus lanreotide in a group of NET patients with relatively aggressive disease and limited therapeutic options. TRIAL REGISTRATION: LOLA is registered at ClinicalTrials.gov (NCT04427787) and EudraCT (2019-004506-10).

Retrospective Analysis of the Correlation of MSI-h/dMMR Status and Response to Therapy for Endometrial Cancer: RAME Study, a Multicenter Experience.

BACKGROUND: There is poor evidence regarding sensitivity to chemotherapy in endometrial cancer (EC) based on microsatellite instability (MSI)/mismatch repair (MMR) status. METHODOLOGY: The RAME study is a retrospective analysis aiming to assess response to chemotherapy in MSI-high (h)/deficient (d) MMR and MSI-low (l)/proficient (p) MMR EC patients. Primary endpoints were recurrence-free survival (RFS) for patients with localized disease and progression-free survival (PFS) and overall survival (OS) in patients with advanced/recurrent disease. RESULTS: A total of 312 patients treated between 2010 and 2022 in four high-volume Multicenter Italian Trial in Ovarian cancer and gynecological malignancies (MITO) centers were selected. In total, 239 patients had endometrioid EC (76.6%), 151 had FIGO stage I at diagnosis (48.9%) and 71 were MSI-h/dMMR (22.8%). Median age was 65 (range 31-91) years. Among patients with localized disease, median RFS was 100.0 months (95% CI 59.4-140.7) for MSI-l/pMMR and 120.9 months (60.0-181.8) for MSI-h/dMMR (p = 0.39). Seventy-seven patients received first-line chemotherapy for advanced/recurrent disease. Patients with MSI-h/dMMR ECs had a significantly worse OS (p = 0.039). In patients receiving platinum-based chemotherapy, no statistically significant differences in PFS (p = 0.21) or OS (p = 0.057) were detected, although PFS and OS were numerically longer in the MSI-l/pMMR population. CONCLUSIONS: Patients with metastatic MSI-h/dMMR EC receiving first-line chemotherapy had a significantly worse OS.

Ki67 as a Predictor of Response to PARP Inhibitors in Platinum Sensitive BRCA Wild Type Ovarian Cancer: The MITO 37 Retrospective Study.

BACKGROUND: There is compelling need for novel biomarkers to predict response to PARP inhibitors (PARPi) in BRCA wild-type (WT) ovarian cancer (OC). METHODS: MITO 37 is a multicenter retrospective study aiming at correlating Ki67 expression at diagnosis with a clinical outcome following platinum treatment and PARPi maintenance. Clinical data were collected from high grade serous or endometroid BRCAWT OC treated with niraparib or rucaparib maintenance between 2010-2021 in 15 centers. Ki67 expression was assessed locally by certified pathologists on formalin-fixed paraffin embedded (FFPE) tissues. Median Ki67 was used as a cut-off. RESULTS: A total of 136 patients were eligible and included in the analysis. Median Ki67 was 45.7% (range 1.0-99.9). The best response to platinum according to median Ki67 was 26.5% vs. 39.7% complete response (CR), 69.1% vs. 58.8% partial response (PR), 4.4% vs. 1.5% stable disease (SD). The best response to PARPi according to median Ki67 was 19.1% vs. 36.8% CR, 26.5% vs. 26.5% PR, 26.5 vs. 25% SD, 27.9% vs. 16.2% progressive disease (PD). No statistically significant differences in progression free survival (PFS) and overall survival (OS) were identified between low and high Ki67. PFS and OS are in line with registration trials. CONCLUSIONS: Ki67 at diagnosis did not discriminate responders to PARPi.

Prescribing pattern of anticoagulants in patients with cancer associated thrombosis: Results of a survey among MITO group and AIOM society.

INTRODUCTION: Low molecular weight heparin (LMWH) has been the backbone of the treatment of cancer associated thrombosis (CAT). Direct-acting oral anticoagulants (DOACs) have shown efficacy and safety not inferior to LMWH and guidelines included DOACs as an option for CAT treatment. Nevertheless, DOACs are still poorly prescribed in patients with cancer. The aim of this survey was to better understand prescription patterns of anticoagulants, in particular of DOACs, especially in gynecological cancers (GCs). METHODS: Our survey was made up of 21 questions, the last four questions addressed to medical doctors (MDs) involved in GCs. An invitation to complete the survey was sent by e-mail to 691 MITO (Multicentre Italian Trials in Ovarian cancer and gynaecologic malignancies) and 2093 AIOM (Associazione Italiana di Oncologia Medica) members. RESULTS: Overall, 113 MDs completed the questionnaire, 69 involved in GCs. Most respondents (46, 41%) were aged 30-40 years old, worked in public hospitals (59, 52.2%), were medical oncologists (86, 76.1%). LMWH was the preferred choice for the treatment of CAT (104, 92%). However, 89 respondents (78.8%) prescribed or asked to prescribe a DOAC for CAT. The major concern about DOACs was the difficulty in verifying the therapeutic effect and the absence of antidotes in case of bleeding (37.9%). In patients with GCs, DOACs were used with niraparib, olaparib, rucaparib and immune checkpoint inhibitors (ICIs) in less than 10 patients by 23%, 20%, 9% and 10.2% of respondents, respectively. CONCLUSION: The responders are aware of the Direct-acting oral anticoagulants option and would like to use them.

MITO39: Efficacy and Tolerability of Pegylated Liposomal Doxorubicin (PLD)-Trabectedin in the Treatment of Relapsed Ovarian Cancer after Maintenance Therapy with PARP Inhibitors-A Multicenter Italian Trial in Ovarian Cancer Observational Case-Control Study.

OBJECTIVE: While PLD-Trabectedin is an approved treatment for relapsed platinum-sensitive ovarian cancer, its efficacy and tolerability has so far not been tested extensively in patients who progress after poly ADP-ribose polymerase inhibitor (PARPi) treatment. METHODOLOGY: This multicenter, retrospective analysis had the objective of comparing patients receiving PLD-Trabectedin after being treated with PARP-I (cases) with PARPi-naïve patients. Descriptive and survival analyses were performed for each group. RESULTS: Data from 166 patients were collected, composed of 109 cases and 57 controls. In total, 135 patients were included in our analyses, composing 46 controls and 89 cases. The median PFS was 11 months (95% IC 10-12) in the control group vs. 8 months (95% IC 6-9) in the case group (p value 0.0017). The clinical benefit rate was evaluated, with an HR for progression of 2.55 (1.28-5.06) for the case group (p value 0.008), persisting when adjusted for BRCA and line with treatment. We compared hematological toxicity, gastro-intestinal toxicity, hand-foot syndrome (HFS), fatigue, and liver toxicity, and no statistically significant disparity was noted, except for HFS with a p value of 0.006. The distribution of G3 and G4 toxicities was also equally represented. CONCLUSION: The MITO39 study showed a statistically significant difference in terms of PFS, suggesting that previous exposure to PARPi might inhibit the efficacy of PLD-Trabectedin. Regarding tolerability, no remarkable disparity was noted; PLD-Trabectedin was confirmed to be a well-tolerated scheme in both groups. To our knowledge, these are the first data regarding this topic, which we deem to be of great relevance in the current landscape.

Corrigendum: Management of metastatic endometrial cancer: physicians' choices beyond the first line after approval of checkpoint inhibitors.

[This corrects the article DOI: 10.3389/fonc.2023.1247291.].

Clinical and Histopathological Predictors of Recurrence in Uterine Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP): A Multicenter Retrospective Cohort Study of Tertiary Centers.

BACKGROUND: The term uterine smooth muscle tumor of uncertain malignant potential (STUMP) indicates a rare, equivocal entity between benign leiomyomas and leiomyosarcomas. In the present study, we evaluated a comprehensive range of clinical, surgical, and pathological features in a large multicenter series of patients with STUMP to identify risk factors for recurrence. METHODS: This is a retrospective study performed by collecting consecutive cases diagnosed between January 2000 and December 2020 in five tertiary centers. Associations between STUMP recurrence and clinicopathological characteristics as well as surgical treatment modality were investigated. RESULTS: Eighty-seven patients affected by STUMP were considered. Of them, 18 cases (20.7%) recurred: 11 as leiomyosarcoma (LMS) and 7 as STUMP. The mean time to recurrence was 79 months. We found that fragmentation/morcellation, epithelioid features, high mitotic count, Ki-67 value > 20%, progesterone receptor (PR) < 83%, and p16 diffuse expression were associated with higher risk of recurrence and shorter recurrence-free survival (RFS). Furthermore, morcellation/fragmentation and mitotic count remained independent risk factors for recurrence and shorter RFS after multivariate analysis, while the presence of epithelioid features was an independent risk factor for recurrence only. CONCLUSIONS: Our results suggest that morcellation is associated with risk of recurrence and shorter RFS, thus it should be avoided if a STUMP is suspected preoperatively. Epithelioid features, high proliferation activity, low PR expression, and diffuse p16 expression are also unfavorable prognostic factors, so patients presenting these features should be closely followed up.

Management of Metastatic Endometrial Cancer: Physicians' Choices Beyond the First Line. A MITO Survey.

Background: Endometrial cancer (EC) therapeutic and diagnostic approaches have been changed by the development of a new prognostic molecular classification, the introduction of dostarlimab in microsatellite instability (MSI) high pre-treated advanced EC patients with further expected innovation deriving from lenvatinib plus pembrolizumab regardless MSI status. How this is and will be translated and embedded in the clinical setting in Italy is not known; this is why we developed Multicentre Italian Trials in Ovarian cancer and gynaecologic malignancies (MITO) survey on the current practice and expected future changes in EC. Methods: We designed a self-administered, multiple-choice online questionnaire available only for MITO members for one month, starting in April 2021. Results: 75.6% of the respondents were oncologists with a specific focus on gynaecologic malignancies and 73.3% of the respondents declared the availability of clinical trials in second line treatment for advanced EC. The therapeutic algorithm in second line was heterogeneous, being the most frequent choice administering anthracyclines followed by endocrine therapy or enrolling in clinical trials. While more than half of the clinicians declared that they performed the molecular classification, only six/45 respondents (13.3%) ran all the tests needed for it. On the other hand, 80% of them declared regular assessment of MSI status with IHC as recommended. The therapeutic approach in MSI high advanced EC patients has changed since dostarlimab approval. Indeed the most frequent choice in second line has been chemotherapy (53.3%) before its availability, while dostarlimab has been preferred in more than three-fourths of the cases (75.6%) after its approval. As for MSS patients, 77.8% of clinicians would choose lenvatinib plus pembrolizumab for them in second line once approved. Conclusions: Despite the selected sample of respondents from Italian MITO centres showing good knowledge of diagnostic and therapeutic innovations in EC, these are not fully implemented in everyday clinics, except for MSI status assessment.

From Uterus to Brain: An Update on Epidemiology, Clinical Features, and Treatment of Brain Metastases From Gestational Trophoblastic Neoplasia.

In this review, we provide the state of the art about brain metastases (BMs) from gestational trophoblastic neoplasia (GTN), a rare condition. Data concerning the epidemiology, clinical presentation, innovations in therapeutic modalities, and outcomes of GTN BMs are comprehensively presented with particular attention to the role of radiotherapy, neurosurgery, and the most recent chemotherapy regimens. Good response rates have been achieved thanks to multi-agent chemotherapy, but brain involvement by GTNs entails significant risks for patients' health since sudden and extensive intracranial hemorrhages are possible. Moreover, despite the evolution of treatment protocols, a small proportion of these patients ultimately develops a resistant disease. To tackle this unmet clinical need, immunotherapy has been recently proposed. The role of this novel option for this subset of patients as well as the achieved results so far are also discussed.

Immunotherapy for Cervical Cancer: Are We Ready for Prime Time?

The prognosis of invasive cervical cancer (CC) remains poor, with a treatment approach that has remained the same for several decades. Lately, a better understanding of the interactions between the disease and the host immune system has allowed researchers to focus on the employment of immune therapy in various clinical settings. The most advanced strategy is immune checkpoint inhibitors (ICIs) with numerous phase II and III trials recently concluded with very encouraging results, assessing single agent therapy, combinations with chemotherapy and radiotherapy. Apart from ICIs, several other compounds have gained the spotlight. Tumor Infiltrating Lymphocytes (TILs) due to their highly selective tumoricidal effect and manageable adverse effect profile have received the FDA's Breakthrough Therapy designation in 2019. The antibody drug conjugate (ADC) Tisotumab-Vedotin has shown activity in metastatic CC relapsed after at least one line of chemotherapy, with a phase III trial currently actively enrolling patients. Moreover, the deeper understanding of the ever-changing immune landscape of CC carcinogenesis has resulted in the development of active therapeutic vaccines. This review highlights the different immunotherapeutic strategies being explored reflects on what role immunotherapy might have in therapeutic algorithms of CC and addresses the role of predictive biomarkers.

Ovarian Cancer Cells in Ascites Form Aggregates That Display a Hybrid Epithelial-Mesenchymal Phenotype and Allows Survival and Proliferation of Metastasizing Cells.

Peritoneal metastases are the leading cause of morbidity and mortality in ovarian cancer. Cancer cells float in peritoneal fluid, named ascites, together with a definitely higher number of non neo-neoplastic cells, as single cells or multicellular aggregates. The aim of this work is to uncover the features that make these aggregates the metastasizing units. Immunofluorescence revealed that aggregates are made almost exclusively of ovarian cancer cells expressing the specific nuclear PAX8 protein. The same cells expressed epithelial and mesenchymal markers, such as EPCAM and αSMA, respectively. Expression of fibronectin further supported a hybrid epithelia-mesenchymal phenotype, that is maintained when aggregates are cultivated and proliferate. Hematopoietic cells as well as macrophages are negligible in the aggregates, while abundant in the ascitic fluid confirming their prominent role in establishing an eco-system necessary for the survival of ovarian cancer cells. Using ovarian cancer cell lines, we show that cells forming 3D structures neo-expressed thoroughly fibronectin and αSMA. Functional assays showed that αSMA and fibronectin are necessary for the compaction and survival of 3D structures. Altogether these data show that metastasizing units display a hybrid phenotype that allows maintenance of the 3D structures and the plasticity necessary for implant and seeding into peritoneal lining.

Biomarkers of Central Nervous System Involvement from Epithelial Ovarian Cancer.

Epithelial ovarian cancer (EOC) is the leading cause of death among women affected by gynaecological malignancies. Most patients show advanced disease at diagnosis (FIGO stage III-IV) and, despite the introduction of new therapeutic options, most women experience relapses. In most cases, recurrence is abdominal-pelvic; however, EOC can occasionally metastasize to distant organs, including the central nervous system. The incidence of brain metastases (BMs) from EOC is low, but it has grown over time; currently, there are no follow-up strategies available. In the last decade, a few biomarkers able to predict the risk of developing BMs from OC or as potential therapeutic targets have been investigated by several authors; to date, none have entered clinical practice. The purpose of this review is to offer a summary on the role of the most relevant predictors of central nervous system (CNS) involvement (hormone receptors; BRCA; MRD1; PD-1/PD-L1) and to highlight possible therapeutic strategies for the management of metastatic brain disease in EOC.

The Role of PARP Inhibitors in the Ovarian Cancer Microenvironment: Moving Forward From Synthetic Lethality.

PARP inhibitors (PARPi) have shown promising clinical results and have revolutionized the landscape of ovarian cancer management in the last few years. While the core mechanism of action of these drugs has been largely analyzed, the interaction between PARP inhibitors and the microenvironment has been scarcely researched so far. Recent data shows a variety of mechanism through which PARPi might influence the tumor microenvironment and especially the immune system response, that might even partly be the reason behind PARPi efficacy. One of many pathways that are affected is the cGAS-cGAMP-STING; the upregulation of STING (stimulator of interferon genes), produces more Interferon ϒ and pro inflammatory cytokines, thus increasing intratumoral CD4+ and CD8+ T cells. Upregulation of immune checkpoints such as PD1-PDL1 has also been observed. Another interesting mechanism of interaction between PARPi and microenvironment is the ability of PARPi to kill hypoxic cells, as these cells show an intrinsic reduction in the expression and function of the proteins involved in HR. This process has been defined "contextual synthetic lethality". Despite ovarian cancer having always been considered a poor responder to immune therapy, data is now shedding a new light on the matter. First, OC is much more heterogenous than previously thought, therefore it is fundamental to select predictive biomarkers for target therapies. While single agent therapies have not yielded significant results on the long term, influencing the immune system and the tumor microenvironment via the concomitant use of PARPi and other target therapies might be a more successful approach.

Differences in PARP Inhibitors for the Treatment of Ovarian Cancer: Mechanisms of Action, Pharmacology, Safety, and Efficacy.

Poly(ADP-ribose) polymerases (PARP) are proteins responsible for DNA damage detection and signal transduction. PARP inhibitors (PARPi) are able to interact with the binding site for PARP cofactor (NAD+) and trapping PARP on the DNA. In this way, they inhibit single-strand DNA damage repair. These drugs have been approved in recent years for the treatment of ovarian cancer. Although they share some similarities, from the point of view of the chemical structure and pharmacodynamic, pharmacokinetic properties, these drugs also have some substantial differences. These differences may underlie the different safety profiles and activity of PARPi.

Brain Metastases from Ovarian Cancer: Current Evidence in Diagnosis, Treatment, and Prognosis.

With this review, we provide the state of the art concerning brain metastases (BMs) from ovarian cancer (OC), a rare condition. Clinical, pathological, and molecular features, treatment options, and future perspectives are comprehensively discussed. Overall, a diagnosis of high-grade serous OC and an advanced disease stage are common features among patients who develop brain metastases. BRCA1 and BRCA2 gene mutations, as well as the expression of androgen receptors in the primary tumor, are emerging risk and prognostic factors which could allow one to identify categories of patients at greater risk of BMs, who could benefit from a tailored follow-up. Based on present data, a multidisciplinary approach combining surgery, radiotherapy, and chemotherapy seem to be the best approach for patients with good performance status, although the median overall survival (<1 year) remains largely disappointing. Hopefully, novel therapeutic avenues are being explored, like PARP inhibitors and immunotherapy, based on our improved knowledge regarding tumor biology, but further investigation is warranted.

Cytoreductive Surgery for Heavily Pre-Treated, Platinum-Resistant Epithelial Ovarian Carcinoma: A Two-Center Retrospective Experience.

Few retrospective studies have shown a benefit in selected patients affected by heavily pre-treated, platinum-resistant ovarian carcinomas (PROCs) who have undergone cytoreduction at relapse. However, the role of tertiary and quaternary cytoreductive surgery is not fully defined. Our aim was to evaluate survival and surgical morbidity and mortality after maximal cytoreduction in this setting. We evaluated all consecutive patients undergoing cytoreduction for platinum-resistance over an 8-year period (2010-2018) in two different centers. Fifty patients (median age 52.5 years, range 34-75) were included; the median number of previous chemotherapy lines was three (range 1-7) and the median number of previous surgeries was one (range 1-4). Completeness of cytoreduction (CC = 0) was achieved in 22 patients (44%). Rates of major operative morbidity and 30-day mortality were 38% and 8%, respectively. Median follow-up was 35 months. The absence of tumor residual (CC = 0) was associated with a significantly better overall survival (OS) compared to the CC > 0 subgroup (median OS 32.9 months (95% CI 21.6-44.2) vs. 4.8 months (95% CI n.a.-9.8), hazard ratio (HR) 4.21 (95% CI 2.07-8.60), p < 0.001). Optimal cytoreduction is feasible and associated with promising OS in selected, heavily pre-treated PROCs. Further prospective studies are required to better define the role of surgery in platinum-resistant disease.

Immuno-Metabolism and Microenvironment in Cancer: Key Players for Immunotherapy.

Immune checkpoint inhibitors (ICIs) have changed therapeutic algorithms in several malignancies, although intrinsic and secondary resistance is still an issue. In this context, the dysregulation of immuno-metabolism plays a leading role both in the tumor microenvironment (TME) and at the host level. In this review, we summarize the most important immune-metabolic factors and how they could be exploited therapeutically. At the cellular level, an increased concentration of extracellular adenosine as well as the depletion of tryptophan and uncontrolled activation of the PI3K/AKT pathway induces an immune-tolerant TME, reducing the response to ICIs. Moreover, aberrant angiogenesis induces a hypoxic environment by recruiting VEGF, Treg cells and immune-suppressive tumor associated macrophages (TAMs). On the other hand, factors such as gender and body mass index seem to affect the response to ICIs, while the microbiome composition (and its alterations) modulates both the response and the development of immune-related adverse events. Exploiting these complex mechanisms is the next goal in immunotherapy. The most successful strategy to date has been the combination of antiangiogenic drugs and ICIs, which prolonged the survival of patients with non-small-cell lung cancer (NSCLC) and hepatocellular carcinoma (HCC), while results from tryptophan pathway inhibition studies are inconclusive. New exciting strategies include targeting the adenosine pathway, TAMs and the microbiota with fecal microbiome transplantation.