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413 Background: Combination therapy with tyrosine kinase inhibitors and anti-PD-1 antibodies can allow selected patients with initially unresectable HCC to convert to surgical resection. We evaluated conversion therapy with a triple combination of lenvatinib (LEN), anti-PD-1 antibodies and transarterial therapy. Methods: We retrospectively searched medical records from 117 consecutive patients with unresectable/advanced HCC who received triple combination therapy between Dec 2018 and Oct 2020 at Tianjin Medical University Cancer Institute & Hospital. Eligible patients were required to have potentially resectable HCC, defined as meeting ≥1 of the following criteria: 1) estimated future liver remnant after radical (R0) resection of < 40% or < 30% in patients with/without cirrhosis, respectively; 2) R0 resection technically difficult to complete; 3) Child-Pugh score ≥7, ECOG performance status ≥1; 4) tumor thrombus in the main portal vein or inferior vena cava; 5) resectable extrahepatic metastases. The primary endpoint was the proportion of patients who underwent a successful resection (conversion rate). Secondary endpoints included objective response rate (ORR), disease control rate (DCR), 6-month disease-free survival (DFS) and safety. Results: Of 37 patients included in the analysis, all received LEN and anti-PD-1 antibodies with transarterial chemoembolization (TACE, n = 22), hepatic arterial infusion chemotherapy (HAIC, n = 9) or both (n = 6). The conversion rate was 40.5% (15) and the ORR and DCR were 67.7% and 86.5% by RECIST v1.1 and 75.7% and 86.5% by mRECIST, respectively. The median conversion time was 4 months (range: 2-15). After a median postoperative follow-up time of 10 months (95% CI, 6.42-13.58), the 6-month DFS rate was 93%. Overall, 89.2% of patients had ≥1 treatment emergent adverse event (TEAE) and 29.7% experienced a Grade 3/4 TEAE, the most common was hypertension (18.9%, n = 7). Conclusions: A triple combination of LEN, anti-PD-1 antibodies and transarterial therapy was well tolerated and effective at converting potentially resectable HCC to resectable disease. These findings warrant confirmation by future prospective studies.

Pulmonary blastoma (PB) is a rare aggressive lung malignancy with a poor prognosis. Surgical resection is the treatment of choice for localized disease, and there are no standard treatment guidelines for metastatic PB. Due to its rareness, its molecular profile has not been elucidated. We present the first case of classic biphasic pulmonary blastoma (CBPB) with CD74-ROS1 rearrangement in a 44-year-old Asian female with stage IV disease diagnosed using capture-based ultra-deep targeted sequencing. It has been reported that ROS1 rearranged lung adenocarcinoma and squamous cell carcinoma are sensitive to crizotinib, an ALK/MET/ ROS1 multitargeted tyrosine kinase inhibitor. However, its efficacy has not been reported in CBPB patients harboring ROS1 rearrangement. This CBPB patient was given crizotinib and she achieved partial response after 1 month of treatment. We report the first clinical evidence of efficacy shown by crizotinib for targeting CD74-ROS1 fusion in CBPB.

Immune checkpoint therapies exhibit impressive efficacy in some patients with melanoma or lung cancer, but the lack of response in most cases presses the question of how general efficacy can be improved. In addressing this question, we generated a preclinical tumor model to study anti-PD-1 resistance by in vivo passaging of Kras-mutated, p53-deficient murine lung cancer cells (p53R172HΔg/+K-rasLA1/+) in a syngeneic host exposed to repetitive dosing with anti-mouse PD-1 antibodies. PD-L1 (CD274) expression did not differ between the resistant and parental tumor cells. However, the expression of important molecules in the antigen presentation pathway, including MHC class I and II, as well as β2-microglobulin, were significantly downregulated in the anti-PD-1–resistant tumors compared with parental tumors. Resistant tumors also contained fewer CD8+ (CD8α) and CD4+ tumor-infiltrating lymphocytes and reduced production of IFNγ. Localized radiotherapy induced IFNβ production, thereby elevating MHC class I expression on both parental and resistant tumor cells and restoring the responsiveness of resistant tumors to anti-PD-1 therapy. Conversely, blockade of type I IFN signaling abolished the effect of radiosensitization in this setting. Collectively, these results identify a mechanism of PD-1 resistance and demonstrate that adjuvant radiotherapy can overcome resistance. These findings have immediate clinical implications for extending the efficacy of anti-PD-1 immune checkpoint therapy in patients. Cancer Res; 77(4); 839–50. ©2016 AACR.

4050 Background: FLOT is the standard perioperative treatment for resectable gastric /gastroesophageal junction (GEJ) adenocarcinoma. However, patient’s outcome is still poor. Toripalimab, a humanized IgG4 monoclonal antibody against programmed cell death receptor-1 (PD-1), has shown remarkable clinical efficacy in various cancers. This trial evaluates the addition of Toripalimab to FLOT for resectable patients. Methods: This is a prospective, single-arm, investigator-initiated phase II trial. Patients with histologically confirmed, resectable, gastric and GEJ adenocarcinoma (≥cT2 or cN+) were enrolled to receive 4 pre-and post-operative cycles of toripalimab (240mg, q2w) plus FLOT (docetaxel 50 mg/m2; oxaliplatin 85 mg/m2; leucovorin 200 mg/m2; 5-FU 2600 mg/m2, q2w). The primary endpoint was pathological complete response rate (pCR). The secondary endpoints included major pathological (complete and nearly complete) response (MPR), and R0-resection rate, 3-year disease-free survival rate, overall survival, and adverse events. Results: In total, of 36 patients were enrolled from June 2019 through Dec 2020. Male, 66.7%; median age, 60y; cT3 8.3%, T4, 83.3%; cN+ 88.9%; GEJ 47%; MSI-H, 5.6%, Her-2neu-positive, 5.6%, EBER-positive, 5.6%). Two patients refused surgery, six patients have not yet completely neoadjuvant treatment. 100% of patients completed the 4 pre-cycle. Patients who had received gastrectomy after neoadjuvant treatment (n=28) were included in this analysis. 6 (21%) patients had operations involving a thoracic approach (oesophagogastrectomy with two field lymphadenectomy), 21 (75%) gastrectomy with D2 lymphadenectomy. 8 (29%) evaluable patients had Clavien-Dindo grade II post-operative complications and 2 (7%) grade IIIA complications; one patient had an anastomotic leakage that was treated endoscopically. There were no emergency re-operations. All 28 patients achieved R0-resection and were discharged home after a median of 12 days (range:7-63) in hospital. 7 （25%）patients achieved pCR (TRG1a) and 12 (42.9%) patients achieved major pathologic response (MPR, TRG1a/b). Treatment-related adverse events (TRAEs) to any drug were reported in 30 (94%) patients. Mostly TRAEs were grade 1-2, the grade 3 or 4 TRAEs included neutropenia (34%), neutropenia (25%), lymphopenia (3%), Alanine aminotransferase increased (3%), hypokalemia (3%) and anaemia (3%). Conclusions: Perioperative toripalimab in combination with FLOT showed promising efficacy with high pCR and MPR rate and well tolerated safety profile in patients with resectable gastric/GEJ adenocarcinoma. This combination regimen might present a new option for patients with locally advanced, resectable gastric/GEJ adenocarcinoma. Clinical trial information: NCT04354662.

Ximei Zhang,1 Baozhong Zhang,1 Fenglin Zang,2 Lujun Zhao,1 Zhiyong Yuan,1 Ping Wang1 1Department of Radiation Oncology, 2Department of Pathology, Cancer Institute and Hospital, Tianjin Medical University, Tianjin, People’s Republic of China Objectives: Data on breast squamous cell carcinoma (SCC) are rare. The aim of this study was to analyze the clinical characteristics and to explore the rational treatment of patients with breast SCC. Patients and methods: We conducted a retrospective review of breast SCC cases treated at our center from 1966 to 2014. The majority of these patients received primary surgery followed by adjuvant chemoradiotherapy, whilst four elderly patients had lumpectomy only. Results: Patients with breast SCC were usually women, and large masses, large proportion of early stage disease, low levels of estrogen receptor expression, less frequent axillary lymph nodes involvement, and unfavorable prognosis were common. The 5-year overall survival and progression-free survival of all patients were 67.2% and 57.8%, respectively. Axillary nodal involvement was a significant prognostic factor for survival. Conclusion: The current results indicated that breast SCC is clinically aggressive and the outcomes were poor. Distant metastasis was the main failure pattern. New strategies will be needed because of the poor outcomes. Keywords: breast metaplastic carcinoma, breast SCC, treatment, surgery, prognosis

Objectives MAP4K5 plays an important role in regulating a range of cellular responses and is involved in Wnt signaling in hematopoietic cells. However, its functions in human malignancies have not been studied. The major objectives of this study are to examine the expression, functions and clinical significance of MAP4K5 in pancreatic ductal adenocarcinoma (PDAC). Materials and Methods The expression levels of MAP4K5, E-cadherin, vimentin, and carboxylesterase 2 (CES2) were examined by immunohistochemistry in 105 PDAC and matched non-neoplastic pancreas samples from our institution. The RNA sequencing data of 112 PDAC patients were downloaded from the TCGA data portal. Immunoblotting and RNA sequencing analysis were used to examine the expression of MAP4K5 and E-cadherin in pancreatic cancer cell lines. The effect of knockdown MAP4K5 using siRNA on the expression of CDH1 and vimentin were examined by Real-time RT-PCR in Panc-1 and AsPC-1 cells. Statistical analyses were performed using IBM SPSS Statistics. Results MAP4K5 protein is expressed at high levels specifically in the pancreatic ductal cells of 100% non-neoplastic pancreas samples, but is decreased or lost in 77.1% (81/105) of PDAC samples. MAP4K5-low correlated with the loss of E-cadherin (P = 0.001) and reduced CES2 expression (P = 0.002) in our patient populations. The expression levels of MAP4K5 mRNA directly correlated with the expression levels of CDH1 mRNA (R = 0.2490, P = 0.008) in the second cohort of 112 PDAC patients from The Cancer Genome Atlas (TCGA) RNA-seq dataset. Similar correlations between the expression of MAP4K5 and E-cadherin were observed both at protein and mRNA levels in multiple pancreatic cancer cell lines. Knockdown MAP4K5 led to decreased CDH1 mRNA expression in Panc-1 and AsPC-1 cells. MAP4K5-low correlated significantly with reduced overall survival and was an independent prognosticator in patients with stage II PDAC. Conclusions MAP4K5 expression is decreased or lost in majority of PDACs. The strong associations between low MAP4K5 expression and loss of E-cadherin, reduced CES2 expression and decreased overall survival may suggest an important role of MAP4K5 in epithelial-to-mesenchymal transition, chemotherapy resistance and tumor progression in pancreatic cancer. Targeting impaired MAP4K5 signaling may represent a new therapeutic strategy for pancreatic cancer.

The mutation and reduction of mitochondrial DNA (mtDNA) have been extensively detected in human cancers. The effects of mitochondrial dysfunction are particularly important in breast cancer, because estrogen-mediated metabolites generate large quantities of local reactive oxygen species in the breast, which directly bind to mtDNA and facilitate neoplastic transformation. To further elucidate the molecular roles of mtDNA in breast cancer, we determined the oxidative status of a breast tumor cell line lacking mtDNA (T47D ρ⁰) and analyzed its susceptibility after exposure to various anticancer drugs as well as different proapoptotic signals. Our data showed that T47D ρ⁰ cells generated significantly increased levels of lactate with concomitantly reduced oxygen consumption and ATP production compared with the wild-type (WT). The amount of reactive oxygen species generation in ρ cells was lowered to approximately 12% that of parental cells, as evidenced by the oxidation of redox-sensitive probes. Although mtDNA depletion did not affect the expression of superoxide dismutase or its activity, the activities of antioxidant enzymes, catalase and glutathione peroxidase, were significantly higher in ρ⁰ cells compared with WT cells. In addition, mtDNA-depleted cells displayed a decreased sensitivity and accumulation of chemotherapeutic drugs (doxorubicin, vincristine, and paclitaxel), potentially because of the upregulated expression of multidrug resistance 1 (MDR1) gene and its product P-glycoprotein. When compared with their WT counterparts, T47D ρ⁰ cells were also more resistant to apoptosis induced by varying concentrations of staurosporine and anti-Fas antibody. Altogether, our results indicate the importance of intact mtDNA for maintaining the proper intracellular oxidative status. These data provide evidence for a possible role of mtDNA content reduction in acquiring an apoptosis-resistant phenotype during breast tumor progression and might contribute to effective therapeutic strategies for this common malignancy.