Search

e15586 Background: In Saudi Arabia, the incidence of colorectal cancer has been increased over the past few years. The optimal treatment beyond the second line is not fully understood. To the best of our knowledge, the efficacy and disease outcomes of triflurodine/tipiracil in Saudi patients with refractory metastatic colorectal cancer(mCRC) has not been studied yet. Our study is a real-life practice evaluation of the efficacy of triflurodine/tipiracil in patients with refractory mCRC. Moreover, the prognosis and the prognostic significance of the different clinical variables have been analyzed. Methods: A retrospective, multi-centers ( 5 centers representative of Saudi Arabia )observational study in patients with mCRC who have received triflurodine/tipiracil beyond oxaliplatin & Irinotecan-based chemotherapy between December 2018-December 2020.We aimed to assess the response to triflurodine/tipiracil, to evaluate the progression-free survival (PFS ), the overall survival (OS), and the associated factors of prognostic significance. Results:The data of 100 patients with refractory mCRC who has received triflurodine/tipiracil have been analyzed. The mean age was 55.2 +11.8 years. Forty-two patients were (42%) females and 58 (58%) were male patients. Sigmoid was the most common primary site of cancer in 35 (35%) patients, followed by rectum 29 (29%). Peritoneal metastasis was present in 17 (23.3%) patients ,liver in 51(56.6%) and lung in 39 (50.7%). Metastatic sites were ≥ 2 in 45 (45%) patients. Metastatic lesions were ≥ 5 in 65 (65%) patients. Xelox chemotherapy regimen was the most commonly used first-line chemotherapy which represents 43%, while Folfiri or Xeliri combination was the most used second line in 57 (60%). For the third line, Folfox or Xelox was used in 81 (83.5%) patients. The fourth line was given to 49 (67.1%). For first-line biological agents, Cetuximab was used most frequently 31 (46.3%).Evaluation of the response to treatment with triflurodine/tipiracil revealed one patient (1%) with a complete response,3 patients (3%) with partial response, 28 (28%) patients with stable disease, and 66 (66%) showed progressive disease. The estimated median progression-free survival was 5 months ( 3.839 - 6.161) and the median overall survival was 12 months (9.732-14.268). The log-rank analysis showed that the baseline neutrophils ≤ 75 % ( P-value= 0.0092) and low hemoglobin level (P-value= 0.0245) were strongly associated with a higher survival. By multivariate Cox regression analysis, the neutrophil count ≤ 75 % was the only independent predictor for survival. Conclusions: Trifluridine/tipiracil is effective in patients with refractory mCRC. The low neutrophil count might predict a better overall survival.

3031 Background: Early clinical trials have demonstrated the safety of chimeric antigen receptor (CAR) T cells targeting glioblastoma (GBM), however, their efficacy remains limited by multiple obstacles including the immunosuppressive tumor microenvironment. Adoptively transferred CAR T cells remain susceptible to inhibition via the engagement of co-inhibitory receptors on their surface such as PD1, BTLA, CTLA4 and LAG3. The subsequent recruitment of Src homology region 2 containing protein tyrosine phosphatase 2 (SHP2) by these receptors to the immune synapse may represent a common mechanism of T cell inhibition, as SHP2 can de-phosphorylate key signaling molecules that mediate T cell activation (including CD28 and CD3ζ). We hypothesized that SHP2 deletion will simultaneously offset the effects of multiple co-inhibitory receptors, thereby improving the anti-tumor activity of CAR T cells. Methods: Electroporation of sgRNA/Cas9 ribonucleoprotein complexes into human T cells was used to knockout (KO) SHP2. Retroviral vector transduction was used to express a clinically-utilized second generation CAR (with a CD28 endodomain) targeting HER2. The phenotype of wild-type (WT) and SHP2KO CAR T cells was evaluated with mass cytometry and flow cytometry. Their anti-tumor function was tested in vitro using the xCELLigence assay (an impedance-based cytotoxicity assay), and in vivo, in an orthotopic xenograft mouse model of GBM. Results: Efficient and reproducible depletion of the SHP2 protein in human T cells was verified using western blotting. The Inference of CRISPR Efficiency (ICE) Assay confirmed efficient editing of the PTPN11 gene encoding SHP2. An anti-HER2 CAR was efficiently expressed in the SHP2KO T cells. SHP2 deletion did not significantly affect CAR T cell expansion, proliferation or baseline phenotype. However, following co-culture with HER2+ LN229-GBM cells, the CD8+ central memory (CCR7+ CD45RA-) and effector memory (CCR7- CD45RA-) subsets were enriched to a greater extent in the SHP2KO CAR T cells. The pattern of cytokine co-expression varied between donors in a single-cell analysis comparing SHP2KO to WT CAR T cells after encountering LN229 cells. Functionally, SHP2KO CAR T cells derived from the majority of healthy donor and patient peripheral blood eliminated LN229 cells more rapidly in vitro. In an orthotopic mouse model of GBM, SHP2KO CAR T cells showed better early control of established LN229 xenografts and improved survival in comparison to WT CAR T cells. Conclusions: SHP2 deletion in CD28ζ.CAR T cells improves their anti-tumor activity.