Mechanisms of resistance to selective RET tyrosine kinase inhibitors in RET fusion-positive non-small-cell lung cancer.

BACKGROUND: Rearranged during transfection (RET) gene fusions are a validated target in non-small-cell lung cancer (NSCLC). RET-selective inhibitors selpercatinib (LOXO-292) and pralsetinib (BLU-667) recently demonstrated favorable antitumor activity and safety profiles in advanced RET fusion-positive NSCLC, and both have received approval by the US Food and Drug Administration for this indication. Insights into mechanisms of resistance to selective RET inhibitors remain limited. PATIENTS AND METHODS: This study was performed at five institutions. Tissue and/or cell-free DNA was obtained from patients with RET fusion-positive NSCLC after treatment with selpercatinib or pralsetinib and assessed by next-generation sequencing (NGS) or MET FISH. RESULTS: We analyzed a total of 23 post-treatment tissue and/or plasma biopsies from 18 RET fusion-positive patients who received an RET-selective inhibitor (selpercatinib, n = 10; pralsetinib, n = 7; pralsetinib followed by selpercatinib, n = 1, with biopsy after each inhibitor). Three cases had paired tissue and plasma samples, of which one also had two serial resistant tissue specimens. The median progression-free survival on RET inhibitors was 6.3 months [95% confidence interval 3.6-10.8 months]. Acquired RET mutations were identified in two cases (10%), both affecting the RET G810 residue in the kinase solvent front. Three resistant cases (15%) harbored acquired MET amplification without concurrent RET resistance mutations, and one specimen had acquired KRAS amplification. No other canonical driver alterations were identified by NGS. Among 16 resistant tumor specimens, none had evidence of squamous or small-cell histologic transformation. CONCLUSIONS: RET solvent front mutations are a recurrent mechanism of RET inhibitor resistance, although they occurred at a relatively low frequency. The majority of resistance to selective RET inhibition may be driven by RET-independent resistance such as acquired MET or KRAS amplification. Next-generation RET inhibitors with potency against RET resistance mutations and combination strategies are needed to effectively overcome resistance in these patients.

An elevated CA 19-9 is associated with invasive cancer and worse survival in IPMN.

BACKGROUND: Current guidelines for IPMN include an elevated serum carbohydrate antigen (CA) 19-9 among the worrisome features. However, the correlation of CA 19-9 with histological malignant features and survival is unclear. Serum CEA is also currently used for preoperative management of IPMN, although its measurement is not evidence-based. Accordingly, we aimed to assess the role of these tumor markers as predictors of malignancy in IPMN. METHODS: IPMN resected between 1998 and 2018 at Massachusetts General Hospital were analyzed. Clinical, pathological and survival data were collected and compared to preoperative levels of CA 19-9 and CEA. Receiver operating characteristic (ROC) and Cox regression analyses were performed considering cut-offs of 37 U/ml (CA 19-9) and 5 µg/l (CEA). RESULTS: Analysis of 594 patients showed that preoperative CA 19-9 levels > 37 U/ml (n = 128) were associated with an increased likelihood of invasive carcinoma when compared to normal levels (45.3% vs. 18.0%, P < 0.001), while there was no difference with respect to high-grade dysplasia (32.9% vs 31.9%, P = 0.88). The proportion of concurrent pancreatic cancer was higher in patients with CA 19-9 > 37 U/ml (17.2% vs 4.9%, P < 0.001). An elevated CA 19-9 was also associated with worse overall and disease-free survival (HR = 1.943, P = 0.007 and HR = 2.484, P < 0.001 respectively). CEA levels did not correlate with malignancy. CONCLUSION: In patients with IPMN, serum CA19-9 > 37 U/ml is associated with invasive IPMN and concurrent pancreatic cancer as well as worse survival, but not with high-grade dysplasia. Serum CEA appears to have minimal utility in the management of these patients.

Clinical activity of programmed cell death 1 (PD-1) blockade in never, light, and heavy smokers with non-small-cell lung cancer and PD-L1 expression ≥50.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are standard therapies for patients with advanced non-small-cell lung cancer (NSCLC) and a programmed death-ligand 1 (PD-L1) tumor proportion score (TPS) ≥50%. Tumor mutation burden (TMB) also predicts response to ICIs but is often not available in real time for decision making in the first-line setting. Smoking exposure can be a proxy for TMB in NSCLC. The impact of smoking status on efficacy of PD-1 blockade in NSCLC patients with PD-L1 TPS ≥50% has not been well defined. PATIENTS AND METHODS: To investigate the relationship between smoking and activity of ICIs in NSCLC, we retrospectively studied 315 patients with NSCLC and PD-L1 TPS ≥50% at five USA academic medical centers. Objective response rates (ORRs), progression-free survival (PFS), and duration of response (DOR) were compared between never (<100 lifetime cigarettes), light (≤10 pack-years), and heavy (>10 pack-years) smokers. A subset of patients underwent next-generation sequencing to estimate TMB. RESULTS: We identified 36 (11%) never, 42 (13%) light, and 237 (75%) heavy smokers with NSCLC and PD-L1 TPS ≥50% treated with ICIs. Objective responses were observed in 27%, 40%, and 40% of never, light, and heavy smokers, respectively (P = 0.180 never versus heavy; P = 1.000 light versus heavy). Median PFS and median DOR were numerically shorter in never and light smokers compared with heavy smokers (PFS 3.0 versus 4.0 versus 5.4 months; median DOR 6.9 versus 10.8 versus 17.8 months), but were not statistically different [PFS: hazard ratio (HR) 1.37, P = 0.135 and HR 1.24, P = 0.272; DOR: HR 1.92, P = 0.217 and HR 1.79, P = 0.141]. CONCLUSIONS: PD-(L)1 inhibitors are associated with antitumor activity in NSCLC with PD-L1 TPS ≥50% regardless of smoking status. Nevertheless, there is a signal of potentially decreased durability among never and light smokers that should be further evaluated. Distinct immunobiologic features may affect initial response versus durability of antitumor immunity to programmed cell death 1 (PD-1) blockade.

Intraductal papillary mucinous neoplasms of the pancreas with concurrent pancreatic and periampullary neoplasms.

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMN) have been reported to be associated with concurrent, distinct pancreatic ductal adenocarcinoma (con-PDAC) in about 8% (range, 4-10%) of resected branch duct (BD) lesions. In addition, other pancreatic and ampullary tumors are occasionally diagnosed with IPMN in patients undergoing pancreatic surgery. The objective of this study is to describe the prevalence, clinicopathologic characteristics and prognosis of IPMN with concurrent pancreatic and ampullary neoplasms, especially con-PDAC. METHODS: The combined databases of pancreatic resections from the Massachusetts General Hospital and the Negrar Hospital, Italy, were analyzed for patients who had been diagnosed with IPMN and concurrent pancreatic or ampullary neoplasms. RESULTS: 2762 patients underwent pancreatic surgery from January 2000 to December 2012. Sixteen percent (n = 441) had pathologically confirmed IPMN and 11% of these (n = 50) had a different distinct synchronous pancreatic neoplasm. The majority of these, 62%, were con-PDAC, followed by neuroendocrine neoplasms (10%) and ampullary carcinoma (10%). Less frequently, mucinous (6%) as well as serous cystic neoplasms (6%), adenosquamous carcinoma (4%) and distal bile duct cancer (2%) were diagnosed. Among all patients with synchronous neoplasms, 66% harbored BD-IPMN, 28% combined IPMN and 6% main duct IPMN. Abdominal pain and/or jaundice were the leading symptoms in half of patients. CONCLUSION: IPMN, mainly BD-IPMN, are associated with con-PDAC in about 7% of patients and account for 62% of all concurrent pancreatic/ampullary neoplasms. Other synchronous neoplasms may be found sporadically with IPMN without a suspected association.

Co-active receptor tyrosine kinases mitigate the effect of FGFR inhibitors in FGFR1-amplified lung cancers with low FGFR1 protein expression.

Targeted therapies are effective in subsets of lung cancers with EGFR mutations and anaplastic lymphoma kinase (ALK) translocations. Large-scale genomics have recently expanded the lung cancer landscape with FGFR1 amplification found in 10-20% of squamous cell carcinomas (SCCs). However, the response rates have been low for biomarker-directed fibroblast growth factor receptor (FGFR) inhibitor therapy in SCC, which contrasts to the relatively high rates of response seen in EGFR mutant and ALK-translocated lung cancers treated with epidermal growth factor receptor (EGFR) inhibitors and ALK inhibitors, respectively. In order to better understand the low response rates of FGFR1-amplified lung cancers to FGFR inhibitors, relationships between gene copy number, mRNA expression and protein expression of FGFR1 were assessed in cell lines, tumor specimens and data from The Cancer Genome Atlas. The importance of these factors for the sensitivity to FGFR inhibitors was determined by analyzing drug screen data and conducting in vitro and in vivo experiments. We report that there was a discrepancy between FGFR1 amplification level and FGFR1 protein expression in a number of these cell lines, and the cancers with unexpectedly low FGFR1 expression were uniformly resistant to the different FGFR inhibitors. Further interrogation of the receptor tyrosine kinase activity in these discordant cell lines revealed co-activation of HER2 and platelet-derived growth factor receptor-α (PDGFRα) caused by gene amplification or ligand overexpression maintained phosphoinositide 3-kinase (PI3K) and MEK/ERK signaling even in the presence of FGFR inhibitor. Accordingly, co-inhibition of FGFR1 and HER2 or PDGFRα led to enhanced drug responses. In contrast, FGFR1-amplified high FGFR1 protein-expressing lung cancers are sensitive to FGFR inhibitor monotherapy by downregulating ERK signaling. Addition of a PI3K inhibitor to these high FGFR1 protein-expressing cancers further sensitized them to FGFR inhibitor. These data reveal that biomarker-directed trials for FGFR1-amplified SCC require assessment of FGFR1 protein expression and uncover novel therapeutic strategies for FGFR1-amplified SCC with low FGFR1 protein expression.

Frequency and significance of calcification in IPMN.

UNLABELLED: The frequency and significance of calcification in intraductal papillary mucinous neoplasms (IPMN) are unknown. We examined calcifications by computed tomography (CT) in a large cohort of IPMNs and correlated them with clinicopathologic characteristics. METHODS: Preoperative contrast-enhanced CT imaging studies of 164 patients with surgically resected IPMN were retrospectively reviewed. Morphologic characteristics of IPMN, presence and type of calcifications, their location, the degree of dysplasia and the epithelial subtype were recorded. Symptoms at the time of diagnosis, history of smoking, and alcohol consumption were obtained from medical records. RESULTS: Of the 164 IPMNs, 68 were branch duct type (Br-IPMN) and 96 main duct (MD-IPMN) or combined type (CT-IPMN); 78 (48%) had a malignant component (CIS and Invasive). Calcifications were present in 33 cases (20%). By type, 16 calcifications were punctate, 11 coarse and 9 eggshell, and by location, 15 were mural, 3 septal, 2 ductal, 1 in the solid component, and 13 in multiple locations. Calcifications were seen more frequently in larger lesions (44 mm vs 32 mm p = 0.002), and when MPD dilation was noted (70% vs 45%, p = 0.023). There was no association between presence of calcification and malignancy, epithelial subtype, or other clinical data. However, malignancy was present in 9/11 IPMN with coarse calcification (p = 0.04), suggesting this may be a worrisome feature. CONCLUSION: Calcification is found in 20% of IPMNs, and is more common in larger lesions. Although its overall presence has no correlation with malignancy, coarse calcification, when combined with other morphologic features, may be a radiologic sign of malignancy.

Pemetrexed-based chemotherapy in patients with advanced, ALK-positive non-small cell lung cancer.

BACKGROUND: Anaplastic lymphoma kinase (ALK)-positive non-small-cell lung cancer (NSCLC) is highly responsive to crizotinib. To determine whether ALK-positive NSCLC is also sensitive to pemetrexed, we retrospectively evaluated progression-free survival (PFS) of ALK-positive versus ALK-negative patients who had been treated with pemetrexed-based chemotherapy for advanced NSCLC. PATIENTS AND METHODS: We identified 121 patients with advanced, ALK-positive NSCLC in the USA, Australia, and Italy. For comparison, we evaluated 266 patients with advanced, ALK-negative, epidermal growth factor receptor (EGFR)-wild-type NSCLC, including 79 with KRAS mutations and 187 with wild-type KRAS (WT/WT/WT). We determined PFS on different pemetrexed regimens. RESULTS: Among 70 ALK-positive patients treated with a platinum/pemetrexed regimen, the median PFS (mPFS) was 7.3 months (95% confidence interval (CI) 5.5-9.5). The mPFS of 51 ALK-positive patients treated with single-agent pemetrexed or nonplatinum/pemetrexed combinations was 5.5 months (2.8-9.0). For ALK-negative patients, PFS on all pemetrexed-based regimens was similar to that of ALK-positive patients, except in the specific setting of first-line platinum/pemetrexed where the mPFS was only 4.2 and 5.4 months in KRAS and WT/WT/WT patients, respectively. However, among patients with a never/light-smoking history (0-10 pack-year smoking history) treated with first-line platinum/pemetrexed, there was no difference in PFS between ALK-positive and ALK-negative patients. CONCLUSIONS: PFS on pemetrexed or nonplatinum/pemetrexed combinations was similar in ALK-positive and ALK-negative patients. PFS on first-line platinum/pemetrexed may be prolonged in never/light-smoking patients regardless of ALK status.

Implementing multiplexed genotyping of non-small-cell lung cancers into routine clinical practice.

BACKGROUND: Personalizing non-small-cell lung cancer (NSCLC) therapy toward oncogene addicted pathway inhibition is effective. Hence, the ability to determine a more comprehensive genotype for each case is becoming essential to optimal cancer care. METHODS: We developed a multiplexed PCR-based assay (SNaPshot) to simultaneously identify >50 mutations in several key NSCLC genes. SNaPshot and FISH for ALK translocations were integrated into routine practice as Clinical Laboratory Improvement Amendments-certified tests. Here, we present analyses of the first 589 patients referred for genotyping. RESULTS: Pathologic prescreening identified 552 (95%) tumors with sufficient tissue for SNaPshot; 51% had ≥1 mutation identified, most commonly in KRAS (24%), EGFR (13%), PIK3CA (4%) and translocations involving ALK (5%). Unanticipated mutations were observed at lower frequencies in IDH and ß-catenin. We observed several associations between genotypes and clinical characteristics, including increased PIK3CA mutations in squamous cell cancers. Genotyping distinguished multiple primary cancers from metastatic disease and steered 78 (22%) of the 353 patients with advanced disease toward a genotype-directed targeted therapy. CONCLUSIONS: Broad genotyping can be efficiently incorporated into an NSCLC clinic and has great utility in influencing treatment decisions and directing patients toward relevant clinical trials. As more targeted therapies are developed, such multiplexed molecular testing will become a standard part of practice.

Co-registered spectrally encoded confocal microscopy and optical frequency domain imaging system.

Spectrally encoded confocal microscopy and optical frequency domain imaging are two non-contact optical imaging technologies that provide images of tissue cellular and architectural morphology, which are both used for histopathological diagnosis. Although spectrally encoded confocal microscopy has better transverse resolution than optical frequency domain imaging, optical frequency domain imaging can penetrate deeper into tissues, which potentially enables the visualization of different morphologic features. We have developed a co-registered spectrally encoded confocal microscopy and optical frequency domain imaging system and have obtained preliminary images from human oesophageal biopsy samples to compare the capabilities of these imaging techniques for diagnosing oesophageal pathology.

Feasibility of endoscopic ultrasound-guided portal vein embolization with Enteryx.

BACKGROUND: Portal vein embolization (PVE) has been used as a preoperative strategy to induce hepatic lobar atrophy and contralateral lobe hypertrophy. We determined the feasibility of endoscopic ultrasound (EUS)-guided Enteryx (EVAL/ethylene-vinyl alcohol copolymer) embolization of the portal vein (EUS-PVE) in an animal model as a potential, minimally invasive, endoscopic technique. METHODS: EUS-guided embolization of the portal vein (EUS-PVE) using Enteryx was performed in a Yorkshire breed swine. Portal pressure measurements were obtained before and after vascular embolization. The animal was carefully monitored for seven days for evidence of abdominal pain, shock, or bleeding. An upper abdominal contrast-CT scan was performed to verify the location of the embolus. RESULTS: The PV pressure increased from 3 mmHg at baseline to a mean of 15 mmHg after EUS-PVE. The CT-scan on day 4 demonstrated Enteryx in the main portal vein with extension into the left branch. At sacrifice on day 7, a solid thrombus was visible grossly and histologically inside the main portal vein and the left branch of the portal vein. CONCLUSIONS: Selective embolization of the portal vein by EUS guidance appears to be feasible and a potential, minimally invasive, preoperative treatment option for patients undergoing extensive hepatectomy.