Introduction. The current management of advanced non-small cell lung cancer (NSCLC) includes the characterization of Programmed Death Ligand-1 (PD-L1) expression for potential immune checkpoint inhibitor treatment. There is currently no available data regarding the patterns of PD-L1 expression in NSCLC, as well as their association with clinicopathologic profile in Filipino patients.Methodology. Clinicopathologic characteristics of 187 consecutive NSCLC clinical samples with PD-L1 testing using the clone 22C3 pharmaDx kit were collected. The presence of stromal tumor-infiltrating lymphocytes (TILs) were assessed in hematoxylin and eosin-stained slides. PD-L1 expression on tumor cells (TC) and stromal TILs were evaluated.Results. Of the 187 cases, there were 112 males and 75 females. The mean age at diagnosis was 66.4 years old (32-92 years old). It is composed of 131 cases of adenocarcinoma, 15 squamous cell carcinoma, 4 adenosquamous carcinoma, 32 non-small cell carcinoma, not otherwise specified, 3 poorly differentiated malignancy, 1 large cell carcinoma, and 1 mucinous carcinoma. Specimen types included 17 pleural fluid cell blocks, 60 tumor cell block samples, and 110 tissue biopsies. Tumor cell PD-L1 expression was identified in 59.1% of the 110 tissue biopsies. PD-L1 TPS for histologic specimens are as follows: TPS ≥50%, TPS 1-49%, and TPS <1% were observed in 23.6%, 35.5%, and 40.9% in our lung cancer cohort, respectively. Of the 77 cytology specimens, 50.6% presented with TC PD-L1 expression. TPS for this subgroup include: 49.4% with no PD-L1 expression, 35.1% with low PD-L1 expression, and 15.6% showing high PD-L1 expression. PD-L1 expression on TC did not correlate with age, sex, or histology for both specimen type subgroups. Stromal tumor-infiltrating lymphocytes were noted in 74.5% of tissue biopsies. Tumor cell block samples did not demonstrate stromal TILs. For tissue biopsies, female gender and TPS 1-49% were more likely to have <50% PD-L1 expression on TILs.
Conclusion.Overall TC PD-L1 expression was observed in more than half (55.6%) of NSCLC patients in our cohort. The prognostic value of PD-L1 and clinical response to immune checkpoint inhibitors in the Filipino population needs to be further investigated.
A 29-year-old Filipino male smoker presented with dyspnea and a right-sided pneumothorax with subsequent chest tube drainage. Chest CT scan revealed multiple diffuse and mostly interconnected thin and thick-walled cystic structures of varying sizes and shapes with most located in both upper lobes.Video-assisted thoracoscopic surgery (VATS) wedge resection of the right lower lobe posterobasal segment and mechanical pleural abrasion were done. Intraoperatively, there were multiple bullae and diffuse small cysts interspersed with normal lung tissue. Histopathology and immunohistochemistry findings revealed pulmonary Langerhans cell histiocytosis (PLCH). Smoking has been hypothesized to induce a clonal proliferative, neoplastic process or a reactive immune activity in PLCH. The patient was advised smoking cessation and is on close follow-up. He is doing well 10 months after hospital discharge. PLCH is a very rare disease and diagnosis was obtained by VATS. To the authors' knowledge, this is also the first fully documented case of PCLH in the Philippines.
We report a case of a 64-year-old Filipino male who initially presented with chronic cough, easy fatigability, and weight loss. Work-ups lead to a diagnosis of lung adenocarcinoma with epidermal growth factor receptor (EGFR) exon 19 deletion. Patient was placed on targeted therapy with Afatinib. He was able to complete 17 months of targeted therapy with relatively stable disease before experiencing recurrence of easy fatigability. Work-ups then lead to a diagnosis of a high-grade neuroendocrine tumor consistent with small cell lung carcinoma (SCLC). Afatinib was then discontinued and the patient was started on Carboplatin and Etoposide. However, after only one cycle, the patient's symptoms progressed and the patient eventually expired. Histological transformation of EGFR-mutant adenocarcinoma to SCLC as a mechanism of resistance to targeted therapy has been documented in literature since 2006. However, to our knowledge, this is the first fully-documented case of histologic transformation occurring in a Filipino patient. As molecular targeted therapy and immunotherapy become standard-of-care in our country, it is of paramount importance that clinicians and pathologists are aware of the various mechanisms of resistance that can occur as a result of these treatments.
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