Controversies and challenges in the pathologic examination of lung resection specimens after neoadjuvant treatment

Neoadjuvant immune checkpoint inhibitors for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. HCC treatment is challenging; surgical resection is the primary curative treatment for early-stage disease, but recurrence rates are high. Immune checkpoint inhibitors (ICIs) are a promising neoadjuvant treatment that can reduce recurrence rates and mortality after surgery and achieve complete/partial responses. Clinical trials provide strong evidence for the efficacy and safety of ICI monotherapy for neoadjuvant HCC treatment.

Pathology of Surgically Resected Lung Cancers Following Neoadjuvant Therapy

In around 30% of patients, non-small cell lung cancer is diagnosed at an advanced but resectable stage. Adding systemic therapy has shown clear benefit over surgery alone in locally advanced disease, and currently, chemo-immunotherapy in the adjuvant or neoadjuvant setting is the new standard for patients without targetable mutations. One major advantage of the neoadjuvant approach is the possibility of an immediate evaluation of the treatment effect, highlighting the role of pathology as an important contributor at the forefront of clinical decision-making and research. This review provides a summary and an update on current guidelines for histological evaluation of treatment effect after neoadjuvant therapy, also known as regression grading, and discusses newer data focusing on areas of evolving questions and controversies, such as the gross examination of the tumor and tumor bed, weighted versus unweighted evaluation approaches, discussion of histologic tumor type-specific cut-offs for major pathologic response, assessment of lymph nodes and regression grading after immunotherapy and targeted therapy. As no data or recommendations exist on regression grading of multiple tumor nodules, a practical approach is recommended. Lastly, we will touch on additional tissue biomarkers and summarize recent advances in the ardently discussed field of using circulating tumor DNA for the evaluation of treatment response.

Therapeutic effect of induction therapy including nab-paclitaxel followed by surgical resection for the patients with locally advanced non-small-cell lung cancer

BACKGROUND

Lung cancer is associated with a high mortality rate worldwide. Non-small-cell lung cancer (NSCLC) is a major subtype of lung cancer. Carboplatin (CBDCA) plus nab-paclitaxel (PTX) has become a standard treatment for advanced unresectable NSCLC. However, treatment with nab-PTX has not been established as a standard therapy for resectable locally advanced (LA)-NSCLC.

METHODS

We conducted a comprehensive study involving consecutive patients with locally advanced NSCLC who underwent induction therapy including nab-PTX followed by surgical resection. Fifteen patients with locally advanced NSCLC underwent induction therapy including nab-PTX followed by surgical resection. Concurrent chemoradiotherapy (CRT) consisted of weekly administration of nab-PTX (50 mg/m2) plus CBDCA (area under the plasma concentration time curve (AUC) 2) and thoracic radiotherapy (50 Gy/25 fractions).

RESULTS

The clinical stages were as follows: IIB (n =1), IIIA (n =12), and IIIC (n =2). Downstaging was observed in 73% (11/15) of patients on comparison with the clinical stage before concurrent CRT. Adverse drug reactions were observed in seven patients. Complete resection was performed in all patients. The re-evaluated pathological stage after pretreatment was diagnosed as stage 0 in three patients, stage IA1 in six, stage IA2 in one, and stage IIIA in five. The pathological effects of previous therapy were as follows: Ef3 (n =3), Ef2 (n =9), and Ef1a (n =3).

CONCLUSION

The therapeutic effect of induction therapy including nab-PTX was promising. Induction CRT, including nab-PTX, followed by resection, may be a viable alternative treatment option for locally advanced NSCLC.

Pathological response and tumor stroma immunogenic features predict long-term survival in non-small cell lung cancer after neoadjuvant chemotherapy

PURPOSE

Major pathological response (MPR) has become a surrogate endpoint for overall survival (OS) in non-small cell lung cancer (NSCLC) after neoadjuvant therapy, however, the prognostic histologic features and optimal N descriptor after neoadjuvant therapy are poorly defined.

METHODS

We retrospectively analyzed data from 368 NSCLC patients who underwent surgery after neoadjuvant chemotherapy (NAC) from January 2010 to December 2020. The percentage of residual viable tumors in the primary tumor, lymph nodes (LN), and inflammation components within the tumor stroma were comprehensively reviewed. The primary endpoint was OS.

RESULTS

Of the 368 enrolled patients, 12.0% (44/368) achieved MPR in the primary tumor, which was associated with significantly better OS (HR, 0.36 0.17-0.77, p = 0.008) and DFS (HR = 0.59, 0.36-0.92, p = 0.038). In patients who did not have an MPR, we identified an immune-activated phenotype in primary tumors, characterized by intense tumor-infiltrating lymphocyte or multinucleated giant cell infiltration, that was associated with similar OS and DFS as patients who had MPR. Neoadjuvant pathologic grade (NPG), consisting of MPR and immune-activated phenotype, identified 30.7% (113/368) patients that derived significant OS (HR 0.28, 0.17-0.46, p < 0.001) and DFS (HR 0.44, 0.31-0.61, p < 0.001) benefit from NAC. Moreover, the combination of NPG and the number of positive LN stations (nS) in the multivariate analysis had a higher C-index (0.711 vs. 0.663, p < 0.001) than the ypTNM Stage when examining OS.

CONCLUSION

NPG integrated with nS can provide a simple, practical, and robust approach that may allow for better stratification of patients when evaluating neoadjuvant chemotherapy in clinical practice.

Pathologic Processing of Lung Cancer Resection Specimens After Neoadjuvant Therapy

Neoadjuvant treatment of non-small cell lung cancer challenges the traditional processing of pathology specimens. Induction therapy before resection allows evaluation of the efficacy of neoadjuvant agents at the time of surgery. Many clinical trials use pathologic tumor response, measured as major pathologic response (MPR, ≤10% residual viable tumor [RVT]) or complete pathologic response (CPR, 0% RVT) as a surrogate of clinical efficacy. Consequently, accurate pathologic evaluation of RVT is crucial. However, pathologic assessment has not been uniform, which is particularly true for sampling of the primary tumor, which instead of the traditional processing, requires different tissue submission because the focus has shifted from tumor typing alone to RVT scoring. Using a simulation study, we analyzed the accuracy rates of %RVT, MPR, and CPR of 31 pretreated primary lung tumors using traditional grossing compared with the gold standard of submitting the entire residual primary tumor and identified the minimum number of tumor sections to be submitted to ensure the most accurate scoring of %RVT, MPR, and CPR. Accurate %RVT, MPR, and CPR calls were achieved in 52%, 87%, and 81% of cases, respectively, using the traditional grossing method. Accuracy rates of at least 90% for these parameters require either submission of all residual primary tumor or at least 20 tumor sections. Accurate %RVT, MPR, and CPR scores cannot be achieved with traditional tumor grossing. Submission of the entire primary tumor, up to a maximum of 20 sections, is required for the most accurate reads.

Predicting pathological response to neoadjuvant or conversion chemoimmunotherapy in stage IB-III non-small cell lung cancer patients using radiomic features

BACKGROUND

To develop a radiomics model based on chest computed tomography (CT) for the prediction of a pathological complete response (pCR) after neoadjuvant or conversion chemoimmunotherapy (CIT) in patients with non-small cell lung cancer (NSCLC).

METHODS

Patients with stage IB-III NSCLC who received neoadjuvant or conversion CIT between September 2019 and July 2021 at Hunan Cancer Hospital, Xiangya Hospital, and Union Hospital were retrospectively collected. The least absolute shrinkage and selection operator (LASSO) were used to screen features. Then, model 1 (five radiomics features before CIT), model 2 (four radiomics features after CIT and before surgery) and model 3 were constructed for the prediction of pCR. Model 3 included all nine features of model 1 and 2 and was later named the neoadjuvant chemoimmunotherapy-related pathological response prediction model (NACIP).

RESULTS

This study included 110 patients: 77 in the training set and 33 in the validation set. Thirty-nine (35.5%) patients achieved a pCR. Model 1 showed area under the curve (AUC) = 0.65, 64% accuracy, 71% specificity, and 50% sensitivity, while model 2 displayed AUC = 0.81, 73% accuracy, 62% specificity, and 92% sensitivity. In comparison, NACIP yielded a good predictive value, with an AUC of 0.85, 81% accuracy, 81% specificity, and 83% sensitivity in the validation set.

CONCLUSION

NACIP may be a potential model for the early prediction of pCR in patients with NSCLC treated with neoadjuvant/conversion CIT.

AI-based histologic scoring enables automated and reproducible assessment of enrollment criteria and endpoints in NASH clinical trials

Clinical trials in nonalcoholic steatohepatitis (NASH) require histologic scoring for assessment of inclusion criteria and endpoints. However, guidelines for scoring key features have led to variability in interpretation, impacting clinical trial outcomes. We developed an artificial intelligence (AI)-based measurement (AIM) tool for scoring NASH histology (AIM-NASH). AIM-NASH predictions for NASH Clinical Research Network (CRN) grades of necroinflammation and stages of fibrosis aligned with expert consensus scores and were reproducible. Continuous scores produced by AIM-NASH for key histological features of NASH correlated with mean pathologist scores and with noninvasive biomarkers and strongly predicted patient outcomes. In a retrospective analysis of the ATLAS trial, previously unmet pathological endpoints were met when scored by the AIM-NASH algorithm alone. Overall, these results suggest that AIM-NASH may assist pathologists in histologic review of NASH clinical trials, reducing inter-rater variability on trial outcomes and offering a more sensitive and reproducible measure of patient therapeutic response.

Primary endpoints to assess the efficacy of novel therapeutic approaches in epidermal growth factor receptor-mutated, surgically resectable non-small cell lung cancer: A review

While the discovery of oncogenic driver mutations has personalized the metastatic non-small cell lung cancer (NSCLC) treatment landscape with effective targeted therapies, implementation of new treatments in resectable NSCLC has been limited due to the long follow-up needed for overall survival (OS). Until recently, treatment for patients with early-stage resectable NSCLC has been limited to perioperative chemotherapy, which provides modest benefits. However, the regulatory acceptance of two surrogate endpoints for OS has allowed recent approval of both adjuvant osimertinib and atezolizumab, providing patients with new treatment options to improve outcomes. In phase 3 oncology trials, OS has historically been viewed as the gold-standard efficacy measure, but disease-free survival and event-free survival (EFS) are now validated surrogate endpoints for OS in clinical trials and should be considered when mature OS data is unavailable. Another potential surrogate endpoint in the adjuvant NSCLC setting is circulating tumor DNA (ctDNA)-based minimal residual disease (MRD), although prospective validation is needed. For neoadjuvant targeted therapies, EFS, major pathologic response and ctDNA-based MRD are potential surrogate endpoints. To fully translate the success of the personalized treatment advances in the metastatic setting to earlier-stage disease, prospective validation studies of these potential surrogate endpoints that can accelerate the evaluation of drug efficacy are needed. A collaborative effort is also needed from all clinical and regulatory parties to collate surrogate endpoint data for large-scale validation. In this review we discuss the trends in surrogate endpoints used in oncology trials, with a focus on considerations for selecting appropriate primary endpoints in early-stage resectable EGFR-mutant NSCLC, an area of unmet need for novel treatment options.

Predictive Biomarkers for Immunotherapy in Lung Cancer: Perspective From the International Association for the Study of Lung Cancer Pathology Committee

Immunotherapy including immune checkpoint inhibitors (ICIs) has become the backbone of treatment for most lung cancers with advanced or metastatic disease. In addition, they have increasingly been used for early stage tumors in neoadjuvant and adjuvant settings. Unfortunately, however, only a subset of patients experiences meaningful response to ICIs. Although programmed death-ligand 1 (PD-L1) protein expression by immunohistochemistry (IHC) has played a role as the principal predictive biomarker for immunotherapy, its performance may not be optimal, and it suffers multiple practical issues with different companion diagnostic assays approved. Similarly, tumor mutational burden (TMB) has multiple technical issues as a predictive biomarker for ICIs. Now, ongoing research on tumor- and host immune-specific factors has identified immunotherapy biomarkers that may provide better response and prognosis prediction, in particular in a multimodal approach. This review by the International Association for the Study of Lung Cancer Pathology Committee provides an overview of various immunotherapy biomarkers, including updated data on PD-L1 IHC and TMB, and assessments of neoantigens, genetic and epigenetic signatures, immune microenvironment by IHC and transcriptomics, and microbiome and pathologic response to neoadjuvant immunotherapies. The aim of this review is to underline the efficacy of new individual or combined predictive biomarkers beyond PD-L1 IHC and TMB.

Neoadjuvant immunotherapy combined with chemotherapy significantly improved patients' overall survival when compared with neoadjuvant chemotherapy in non-small cell lung cancer: A cohort study

BACKGROUND

Programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) inhibitors displayed considerable advantages in neoadjuvant therapy of non-small cell lung cancer (NSCLC), but the specific application of neoadjuvant immunotherapy has not been well determined, and the long-term prognostic data of neoadjuvant immunochemotherapy combined with surgical resection of NSCLC remains limited. In this study, we intended to assess the efficacy of the neoadjuvant therapy of the PD-1 inhibitor and long-term prognosis in patients with resectable NSCLC.

METHODS

We retrospectively analyzed NSCLC surgical patients treated with neoadjuvant therapy in our hospital, and divided them into a neoadjuvant chemotherapy group and a neoadjuvant immunotherapy combined with chemotherapy group. The propensity score matching method was used to evaluate the effectiveness of immunotherapy combined with chemotherapy in the treatment of resectable lung cancer, and the long-term prognosis of these two groups was compared.

RESULTS

A total of 62 cases were enrolled, including 20 patients (20/62, 32.26%) in the immunotherapy group and 42 patients (42/62, 67.74%) in the chemotherapy group. The clinical baseline data of these two groups were balanced. In the immunotherapy group, all patients had tumor regression in imaging finding (tumor regression ratio: 11.88% - 75.00%). In the chemotherapy group, 30 patients had tumor regression (tumor regression ratio: 2.70% - 58.97%). The R0 removal rates of cancers were comparable between the immunotherapy group and chemotherapy group (19/20, 95.00% vs. 39/42, 92.86%, P=1.000). The two groups were balanced in complete minimally invasive surgery, pneumonectomy, operative duration, blood loss, postoperative complications, and hospital stay. The immunotherapy group had more sleeve resection (36.84% vs. 10.26%, p=0.039) including bronchial sleeve and vascular sleeve, higher pathological complete response (pCR) rate (57.89% vs. 5.13%, P<0.001) and major pathologic response (MPR) rate (78.95% vs. 10.26%, P<0.001). There were no differences in survival curves for: smoker and non-smoker, squamous cell carcinoma and adenocarcinoma, or right lung cancer and left lung cancer. Moreover, patients who achieved MPR (including pCR) had significantly better overall survival (OS) and disease-free survival (DFS). Patients in immunotherapy group had significantly better OS and longer DFS than those in chemotherapy group.

CONCLUSIONS

In conclusion, neoadjuvant immunotherapy combined with chemotherapy can provide better OS and DFS and improving pCR and MPR rates by shrinking tumors.This study has been registered in the Chinese Clinical Trial Registry, number ChiCTR2200060433. http://www.chictr.org.cn/edit.aspx?pid=170157&htm=4.

Assessing Pathologic Response in Resected Lung Cancers: Current Standards, Proposal for a Novel Pathologic Response Calculator Tool, and Challenges in Practice

The efficacy of neoadjuvant treatment for NSCLC can be pathologically assessed in resected tissue. Major pathologic response (MPR) and pathologic complete response (pCR), defined as less than or equal to 10% and 0% viable tumor cells, respectively, are increasingly being used in NSCLC clinical trials to establish them as surrogate end points for efficacy to shorten time to outcome. Nevertheless, sampling and MPR calculation methods vary between studies. The International Association for the Study of Lung Cancer recently published detailed recommendations for pathologic assessment of NSCLC after neoadjuvant treatment, with methodology being critical. To increase methodological rigor further, we developed a novel MPR calculator tool (MPRCT) for standardized, comprehensive collection of percentages of viable tumor, necrosis, and stroma in the tumor bed. In addition, tumor width and length in the tumor bed are measured and unweighted and weighted MPR averages are calculated, the latter to account for the varying proportions of tumor beds on slides. We propose sampling the entire visible tumor bed for tumors having pCR regardless of size, 100% of tumors less than or equal to 3 cm in diameter, and at least 50% of tumors more than 3 cm. We describe the uses of this tool, including potential formal analyses of MPRCT data to determine the optimum sampling strategy that balances sensitivity against excessive use of resources. Solutions to challenging scenarios in pathologic assessment are proposed. This MPRCT will facilitate standardized, systematic, comprehensive collection of pathologic response data with a standardized methodology to validate studies designed to establish MPR and pCR as surrogate end points of neoadjuvant treatment efficacy.

Neoadjuvant Immunotherapy: Leveraging the Immune System to Treat Early-Stage Disease

Given the success of immunotherapy in treating patients with metastatic disease in a variety of tumor types, there is tremendous enthusiasm for expanding the use of immunotherapy to those with early-stage cancer. Administering immunotherapy in the neoadjuvant, preoperative setting is a biologically sound approach because preclinical studies have shown that stronger and broader immune responses can be generated if immunotherapy is administered while the tumor and/or draining lymph nodes are intact. It is therefore likely that administering immunotherapy preoperatively will generate optimal immune responses, leading to high rates of pathologic response as well as improved long-term survival. Although neoadjuvant immunotherapy is currently only approved for use in combination with chemotherapy in triple-negative breast cancer and non-small cell lung cancer, it is anticipated that ongoing and future clinical trials will further define the role of neoadjuvant immunotherapy in many cancer types. These trials should be designed with appropriate survival endpoints and rigorous correlative studies to include imaging and biospecimen-based analyses to address currently unanswered questions that must be resolved to optimize the use of immunotherapy in early-stage disease.

Updated Prognostic Factors in Localized NSCLC

Lung cancer is the most common cause of cancer mortality worldwide, and non-small cell lung cancer (NSCLC) represents 80% of lung cancer subtypes. Patients with localized non-small cell lung cancer may be considered for upfront surgical treatment. However, the overall 5-year survival rate is 59%. To improve survival, adjuvant chemotherapy (ACT) was largely explored and showed an overall benefit of survival at 5 years < 7%. The evaluation of recurrence risk and subsequent need for ACT is only based on tumor stage (TNM classification); however, more than 25% of patients with stage IA/B tumors will relapse. Recently, adjuvant targeted therapy has been approved for EGFR-mutated resected NSCLC and trials are evaluating other targeted therapies and immunotherapies in adjuvant settings. Costs, treatment duration, emergence of resistant clones and side effects stress the need for a better selection of patients. The identification and validation of prognostic and theranostic markers to better stratify patients who could benefit from adjuvant therapies are needed. In this review, we report current validated clinical, pathological and molecular prognosis biomarkers that influence outcome in resected NSCLC, and we also describe molecular biomarkers under evaluation that could be available in daily practice to drive ACT in resected NSCLC.

Real-World Effectiveness and Prognostic Factors Analysis of Stages I-III Non-Small Cell Lung Cancer Following Neoadjuvant Chemo-Immunotherapy or Neoadjuvant Chemotherapy

Purpose: Immune checkpoint inhibitors (ICIs) have been successfully used in many clinical trials related to immunotherapy. This study aimed to investigate the clinical efficacy of ICIs and prognostic factors in patients with resectable non-small cell lung cancer (NSCLC) following neoadjuvant therapy in the real world.

Methods: A total of 170 consecutive patients were finally selected and divided into two groups: the preoperative chemotherapy group (n = 91) and the chemo-immunotherapy group (n = 79). The primary endpoint was disease-free survival (DFS). The secondary endpoints were pathological response, clinical response, pathological nodal disease, and ability of multivariate Cox regression analysis to predict survival. Survival was estimated using Kaplan–Meier method and compared using log-rank test.

Results: There was a statistically significant difference in DFS between the two groups (log-rank test, P = 0.019). Multivariate Cox regression analysis showed that maximum tumor diameter (P = 0.016), higher lymph node stage (ypN1, P = 0.016; ypN2, P <0.001), and major pathological response not achieved (non-major pathological response [MPR], P = 0.011) were independent prognostic factors for worse DFS.

Conclusion: Neoadjuvant chemo-immunotherapy yields better effects in pathological and clinical response than chemotherapy alone, which is also associated with longer DFS in the treatment of locally advanced NSCLC. Moreover, a larger tumor specimen diameter, higher ypN staging, and non-MPR after neoadjuvant therapy were associated with worse prognosis.

Neoadjuvant immune checkpoint inhibitors in resectable non-small-cell lung cancer: a systematic review

Background

The neoadjuvant use of immune checkpoint inhibitors (ICIs) in resectable non-small-cell lung cancer (NSCLC) is currently an area of active ongoing research. The place of neoadjuvant ICIs in the treatment guidelines needs to be determined. We carried out a systematic review of published data on neoadjuvant ICIs in resectable NSCLC to study its efficacy and safety.

Patients and methods

A literature search was carried out using the MEDLINE (PubMed) and Embase databases to retrieve articles and conference abstracts of clinical trials measuring the efficacy [major pathological response (MPR) and pathological complete response (pCR)] and safety (failure to undergo resection, surgical delay, treatment-related adverse events (trAEs) grade ≥3) of neoadjuvant immunotherapy in resectable NSCLC until July 2021.

Results

Nineteen studies with a total of 1066 patients were included in this systematic review. Neoadjuvant immunotherapy was associated with improved pathological response rates, especially in combination with chemotherapy. Using mono ICI, dual therapy–ICI, chemoradiation–ICI, radiotherapy–ICI, and chemo–ICI, the MPR rates were 0%-45%, 50%, 73%, 53%, and 27%-86%, respectively. Regarding pCR, the rates were 7%-16%, 33%-38%, 27%, 27%, and 9%-63%, respectively. Safety endpoints using monotherapy–ICI, dual therapy–ICI, chemoradiation–ICI, radiotherapy–ICI, and chemo–ICI showed a failure to undergo resection in 0%-17%, 19%-33%, 8%, 13%, and 0%-46%, respectively. The trAEs grade ≥3 rates were 0%-20%, 10%-33%, 7%, 23%, and 0%-67%, respectively.

Conclusion

In patients with resectable NSCLC stage, neoadjuvant immunotherapy can improve pathological response rates with acceptable toxicity. Further research is needed to identify patients who may benefit most from this approach, and adequately powered trials to establish clinically meaningful benefits are awaited.

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Neoadjuvant strategies involving immunotherapy are currently being investigated in NSCLC.

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Neoadjuvant immunotherapy was associated with improvement in pathological response rates.

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Neoadjuvant immunotherapy can be safe and feasible with acceptable surgical delay and trAEs.

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Further research is needed to identify patients benefiting most from these approaches.

Lung Cancer Surgery after Neoadjuvant Immunotherapy

In early-stage lung cancer, recurrences are observed even after curative resection. Neoadjuvant immunotherapy might be a promising approach to eliminate micrometastasis and to potentially reduce recurrence rates and improve survival. Early trials have shown encouraging rates of pathologic response to neoadjuvant therapy and have demonstrated that surgery can be safely performed after neoadjuvant immunotherapy with various agents and in combination with chemo-(radio)therapy. However, whether these response rates translate into improved disease-free survival rates and overall survival rates remains to be determined by ongoing phase III studies.

Neoadjuvant immunotherapy is reshaping cancer management across multiple tumour types: The future is now!

The Italian Network for Tumor Biotherapy (Network Italiano per la Bioterapia dei Tumori [NIBIT]) Foundation hosted its annual 2020 Think Tank meeting virtually, at which representatives from academic, clinical, industry, philanthropic, and regulatory organisations discussed the role of neoadjuvant immunotherapy for the treatment of cancer. Although the number of neoadjuvant immunotherapeutic trials is increasing across all malignancies, the Think Tank focused its discussion on the status of neoadjuvant trials in cutaneous melanoma (CM), muscle-invasive urothelial bladder cancer (MIBC), head and neck squamous cell carcinoma (HNSCC), and pancreatic adenocarcinoma (PDAC). Neoadjuvant developments in CM are nothing short of trailblazing. Pathologic Complete Response (pCR), pathologic near Complete Response, and partial Pathologic Responses reduce 90-100% of recurrences. This is in sharp contrast to targeted therapies in neoadjuvant CM trials, where only a pCR seems to reduce recurrence. The pCR rate after neoadjuvant immunotherapy varies among the different malignancies of CM, MIBC, HNSCC, and PDAC and may be associated with different reductions of recurrence rates. In CM, emerging evidence suggests that neoadjuvant immunotherapy with anti-CTLA-4 plus anti-PD1 is a game changer in patients with palpable nodal Stage III or resectable Stage IV disease by curing more patients, reducing recurrences and the need for surgical interventions, such as lymph node dissections and metastasectomies. The Think Tank panel discussed future approaches on how to optimise results across different tumour types. Future approaches should include reducing monocyte-mediated (tumour-associated macrophages) and fibroblast-mediated (cancer-associated fibroblasts) barriers in the tumour microenvironment to facilitate the recruitment of immune cells to the tumour site, to reduce immune-suppressive mediators, and to increase antigen presentation at the site of the tumour.