Bibhusal Thapa

Assessing tumor-infiltrating lymphocytes in solid tumors: a practical review for pathologists and proposal for a standardized method from the International Immuno-Oncology Biomarkers Working Group: part 2: TILs in melanoma, gastrointestinal tract carcinomas, non-small cell lung carcinoma and mesothelioma, endometrial and ovarian carcinomas, squamous cell carcinoma of the head and neck, genitourinary carcinomas, and primary brain Tumors

Assessment of the immune response to tumors is growing in importance as the prognostic implications of this response are increasingly recognized, and as immunotherapies are evaluated and implemented in different tumor types. However, many different approaches can be used to assess and describe the immune response, which limits efforts at implementation as a routine clinical biomarker. In part 1 of this review, we have proposed a standardized methodology to assess tumor-infiltrating lymphocytes (TILs) in solid tumors, based on the International Immuno-Oncology Biomarkers Working Group guidelines for invasive breast carcinoma. In part 2 of this review, we discuss the available evidence for the prognostic and predictive value of TILs in common solid tumors, including carcinomas of the lung, gastrointestinal tract, genitourinary system, gynecologic system, and head and neck, as well as primary brain tumors, mesothelioma and melanoma. The particularities and different emphases in TIL assessment in different tumor types are discussed. The standardized methodology we propose can be adapted to different tumor types and may be used as a standard against which other approaches can be compared. Standardization of TIL assessment will help clinicians, researchers and pathologists to conclusively evaluate the utility of this simple biomarker in the current era of immunotherapy.

The Immune Microenvironment, Genome-wide Copy Number Aberrations, and Survival in Mesothelioma

Introduction: Results of recent clinical studies of immune checkpoint inhibitors in malignant pleural mesothelioma (MPM) have dampened initial enthusiasm. However, the immune environment and targets of these treatments such as programmed cell death protein 1 and its ligand programmed death ligand 1 (PD‐L1) have not been well characterized in MPM. Using a large cohort of patients, we investigated PD‐L1 expression, immune infiltrates, and genome‐wide copy number status and correlated them to clinicopathological features. Methods: Tissue microarrays were constructed and stained with PD‐L1(clone E1L3N [Cell Signaling Technology, Danvers, MA]), cluster of differentiation 4, cluster of differentiation 8, and forkhead box P3 antibodies. PD‐L1 positivity was defined as at least 5% membranous staining regardless of intensity, and high PD‐L1 positivity was defined as at least 50%. Genomic DNA from a representative subset of 113 patients was used for genome‐wide copy number analysis. The percent genome alteration was computed as a proxy for genomic instability, and statistical analyses were used to relate copy number aberrations to other variables. Results: Among 329 patients evaluated, PD‐L1 positivity was detected in 130 of 311 (41.7%), but high PD‐L1 positivity was seen in only 30 of 311 (9.6%). PD‐L1 positivity correlated with nonepithelioid histological subtype and increased infiltration with cluster of differentiation 4–positive, cluster of differentiation 8–positive, and forkhead box P3–positive lymphocytes. High PD‐L1–positive expression correlated with worse prognosis (hazard ratio = 2.37, 95% confidence interval: 1.57–3.56, p < 0.001) in univariate analysis but not in multivariate analysis. Higher percent genome alteration was associated with epithelioid histological subtype and poorer survival (hazard ratio = 1.59, 95% confidence interval: 1.01–2.5, p = 0.04) but not PD‐L1 expression. Conclusions: PD‐L1 expression was associated with nonepithelioid MPM, poor clinical outcome, and increased immunological infiltrates. Increased genomic instability did not correlate with PD‐L1 expression but was associated with poorer survival.

Immunotherapy for malignant mesothelioma: reality check

ABSTRACT Introduction: Initial data of immune based therapy showed promise for improving malignant mesothelioma (MM) treatment. However, the results of such treatments have neither been predictable nor consistent and recent clinical studies of immune checkpoint inhibitors in MM have dampened initial enthusiasm. Areas covered: We comprehensively discuss the basis, modalities and updated results of immunotherapy in MM. An online search was conducted for relevant literature and abstracts of recent meetings. Expert commentary: Although initial studies have demonstrated proof of principle that manipulating the immune checkpoint axis holds promise in MM, results of some recent large studies using checkpoint inhibitors have been disappointing. This is not surprising given the low mutational load in MM and suggests that single agent immunotherapy has limited benefit in this disease. We believe that in order to demonstrate durable survival benefits, they will need to be used in combination approaches with other immunotherapies, vaccines or chemotherapy.

Digital PCR of genomic rearrangements for monitoring circulating tumour DNA

Identifying circulating tumour DNA (ctDNA) for monitoring of cancer therapy is dependent on the development of readily designed, sensitive cancer-specific DNA markers. Genomic rearrangements that are present in the vast majority of cancers provide such markers.Tumour DNA isolated from two fresh-frozen lung tumours underwent whole genome sequencing. Genomic rearrangements were detected using a new computational algorithm, GRIDSS. Four genomic rearrangements from each tumour were chosen for further study using rearrangement-specific primers. Six of the eight rearrangements tested were identified as tumour-specific, the remaining two were present in the germline. ctDNA was quantified using digital PCR for the tumour genomic rearrangements in patient blood. Interestingly, one of the patients had no detectable ctDNA either prior to or post surgery although the rearrangements were readily detectable in the tumour DNA.This study demonstrates the feasibility of using digital PCR based on genomic rearrangements for the monitoring of minimal residual disease. In addition, whole genome sequencing provided further information enabling therapeutic choices including the identification of a cryptic EGFR exon 19 deletion in one patient and the identification of a high somatic mutation load in the other patient. This approach can be used as a model for all cancers with rearranged genomes.

LACES and bootstraps: the hunt for prognostic and predictive markers for adjuvant therapy in NSCLC

The benefit from adjuvant chemotherapy in resected non-small cell lung cancer (NSCLC) is modest with an overall survival (OS) benefit of only ~5% demonstrated in the Lung Adjuvant Cisplatin Evaluation (LACE) meta-analysis (1).

Brief Report: Pembrolizumab as palliative immunotherapy in malignant pleural mesothelioma

Introduction: There is no approved second‐line treatment for malignant pleural mesothelioma (MPM). On the basis of promising early results, pembrolizumab was used off‐label in Switzerland and Australia. We investigated outcomes in association with clinicopathological features and expression of programmed death ligand 1 (PD‐L1). Methods: Registry data in Australia and Switzerland were pooled. Patient characteristics, including age, sex, histological subtype, and previous treatments were captured. Outcomes were assessed locally. PD‐L1 expression was categorized as negative (<5%), intermediate (5%‐49%), and high (≥50%). Results: A total of 93 patients (48 from Switzerland and 45 from Australia) were treated; 68 patients (73%) had epithelioid MPM, and 67 (72%) had an Eastern Cooperative Oncology Group performance status of 0 or 1. Pembrolizumab was the second‐line treatment in 48 of 93 patients (52%). PD‐L1 expression results were available for 66 patients (71%). Most (68%) were negative, 18% were intermediate, and 14% were high for PD‐L1 expression. In the full cohort, the overall response rate (ORR) was 18%, the median progression‐free survival (mPFS) was 3.1 months, and the median overall survival was 7.2 months. In patients with an Eastern Cooperative Oncology Group performance status of 0 or 1 and only one previous systemic treatment (n = 35), the ORR was 37%, the mPFS was 3.7 months, and the median overall survival was 10.2 months. The nonepitheloid histological subtype showed an improved ORR (24% versus 16% [p = 0.54) and mPFS (5.6 versus 2.8 months [p = 0.02]). Compared with intermediate and negative PD‐L1 expression, high PD‐L1 expression was associated with an improved ORR (44% versus 42% versus 11% [p = 0.01]) and mPFS (6.2 versus 3.9 versus 2.7 months [p = 0.04]). Toxicity was as expected. Conclusion: These real‐world data demonstrate similar response rates but inferior survival compared with those in early‐phase trials. High PD‐L1 expression and nonepitheloid histological subtype were associated with greater activity. Anti–PD‐L1 immunotherapy is a reasonable second‐line therapy in patients with MPM.

Surgery for parasitic lung infestations: roles in diagnosis and treatment

Pulmonary parasitic infestations are a worldwide problem associated with significant morbidity and socioeconomic impact. They are known to have varied clinical presentations and radiological appearances. Prevention of parasite transmission and medical treatment of cases form the two pillars of control of these diseases. The role of surgery is limited to the diagnosis and definitive treatment of the minority of pulmonary parasitic afflictions, most notably hydatidosis. Despite surgery being established as the treatment of choice in pulmonary hydatid cysts (PHCs) for over half a century, variations and unresolved controversies persist regarding the best surgical technique. Complications brought on by cyst rupture, multiplicity and multi-organ involvement add complexity to treatment decisions. The development of video-assisted thoracoscopic surgery (VATS) brings the promise of reduced peri-operative morbidity but is yet to be universally accepted as a safe technique. In this review, we endeavor to discuss the common pulmonary infestations focusing on the current trends and controversies surrounding surgery for PHC.

Is Mesothelioma in China Rare or Misdiagnosed

http://dx.doi.org/10.1016/j.jtho.2017.02.004 In the era of targeted therapies and indeed immunotherapy, confirming the site of tumor origin is critical in tailoring therapies, predicting responses, and determining prognosis. A history of asbestos exposure, often more than 40 years before the development of malignancy, alerts clinicians to the potential of a diagnosis of malignant mesothelioma (MM) when tumors of the pleura and peritoneum are investigated. However, in up to 20% of cases, no documented history of exposure is found and this number can be much higher, up to 60%, in women. Although the incidence of MM is well documented in many Western countries, in China the reported incidence is lower than would be expected on the basis of cumulative and continued use of asbestos. This low incidence may be a reflection of reduced reporting rates or limitations in diagnostic accuracy owing to the experience of the pathologist, access to adequate tissue specimens, and availability and use of an adequate panel of immunohistochemical (IHC) markers (Table 1), all of which are factors that improve the diagnostic accuracy of a rare and often difficult to diagnose cancer. Biopsy specimens that include surrounding tissues and structures, including subpleural fat, chest wall tissues, visceral pleura, and lung, are essential for the correct diagnosis of MM, as the most robust histologic indicator of malignancy is invasion outside the pleura. This can often be difficult to demonstrate in small biopsy specimens such as closed percutaneous needle core biopsies, and it is impossible in cytological specimens. The ability to perform a panel of IHC studies that includes markers both positive and negative for MM also requires ample tumor tissue. Reliance on smaller samples obtained from closed percutaneous needle core biopsies and cytological examination may lead to misdiagnosis or may be nondiagnostic. In our own experience of retrospectively reviewing and confirming the diagnosis of pleural MM by using the IHC markers currently recommended for MM in patients whose MM was diagnosed between 1988 and 2014, we were unable to establish the diagnosis of MM in only five of 376 patients (1.5%). This was despite patients from the earlier period of the study having had no IHC evaluation at time of initial diagnosis. In contrast to the study in this issue of the Journal of Thoracic Oncology from Guo et al., all of our samples were surgically obtained large pleural biopsy samples. Therefore, the need for adequately sized biopsy samples with attached tissues outside the pleura needs to be highlighted, especially in centers with limited diagnostic experience with MM. In this context, it is of concern that Guo et al. were able to confirm the diagnosis in only 52 of 92 cases (56%), including 12 of 34 pleural and 38 of 56 peritoneal tumors that were originally diagnosed as MM. In part, this most likely represents differences in IHC markers available over the broad time period of this study. Indeed the unusual clinical phenotype of these patients, namely, young and predominantly female patients with limited history of asbestos exposure, also indicates that the pretest probability should have been low, suggesting that the incorrect diagnosis of mesothelioma was made predominantly on morphological grounds, with limited tissue samples and without application of an adequate IHC panel. Biopsy samples inadequate for diagnosis confirmation were documented in eight of 22 pleural (36%) and 10 of 18 peritoneal (55%) samples. Given that peritoneal MM is less common than pleural MM, it is also surprising that there were fewer false positives in this group, which may indicate better access to tumor tissue as well as the surgeon perhaps noting normal gynecological and adnexal structures intraoperatively. Given the high rate of false positives, it