Targeted monoclonal antibody therapy against Epidermal Growth Factor Receptor (EGFR) is a leading treatment modality against metastatic colorectal cancer (mCRC). However, with the emergence of KRAS and BRAF mutations, resistance was inevitable. Cells harboring these mutations overexpress Glucose Transporter 1 (GLUT1) and sodium-dependent vitamin C transporter 2 (SVCT2), which enables intracellular vitamin C transport, leading to reactive oxygen species generation and finally cell death. Therefore, high dose vitamin C is proposed to overcome this resistance. A comprehensive search strategy was adopted using Pubmed and MEDLINE databases (up to 11 August 2022). There are not enough randomized clinical trials to support its use in the clinical management of mCRC, except for a subgroup analysis from a phase III study. High dose vitamin C shows a promising role in overcoming EGFR resistance in mCRC with wild KRAS mutation with resistance to anti-epidermal growth factor inhibitors and in patients with KRAS and BRAF mutations.

212 Background: In patients with locally advanced rectal cancer (LARC), magnetic resonance imaging is the most accurate non-invasive staging tool, enabling response assessment to total neoadjuvant therapy. Wang et al had reported that 46.6% of patients with Magnetic Resonance Tumor Regression Grade 1 (mrTRG=1; complete radiologic response) achieved pathologic complete response (pCR; no residual tumor cells). We reported previously in a Phase II Averectal study the correlation between pre-treatment biopsy Immunoscore (IS) and pCR probability (68% ± 22 SD in patients with a high IS as opposed to 52% ± 22 SD in patients with a low IS; P=0.036). This study explores the value of combining IS and mrTRG to predict pCR among LARC patients. Methods: This is an open-label, single-arm multicenter stage-2 phase II study investigating the efficacy and safety of 5 fractions of short course radiotherapy, followed by 6 cycles of mFOLFOX-6 plus avelumab, followed by Total Mesorectal Excision (TME), in patients with LARC. Mean density percentiles of CD3 and CD8 positive T cells infiltrating the tumor and the invasive margin in baseline tissue samples were used to calculate IS (62% is considered the cutoff between high and low IS). Baseline and post treatment MRI were reviewed by two independent radiologists to measure mrTRG and other variables. Results: Between July 2018 and October 2020, 44 patients were accrued, out of which 40 (90%) completed at least 1 cycle of mFOLFOX/Avelumab and underwent TME. Of the 40, 36 (90%) had baseline IS, mrTRG (pre-post treatment) and pTRG (pathologic Tumor Regression Grade) assessed. Out of 36, 15 (41.6%) achieved pCR, 24 (66.7%) had mrTRG=1 and 22 (61%) had high IS. Of the high IS (n=22) patients, 10 (45.45%) achieved pCR. Also, out of 24 patients with mrTRG=1, 11 (45.8%) attained pCR. Most importantly, of the patients with combined high IS and mrTRG=1 (n=14), 11 (78.6%) achieved pCR. In patients with both mrTRG=1 and high IS, pCR rate was 78.6% (11/14). This result is significantly different from pCR rate for patients with either high IS (10/22, 45.45%) or mrTRG=1 (11/24, 45.8%) with P=0.0247 and P=0.0243 respectively. Conclusions: Combining both IS and mrTRG achieved a promising predictive value for pCR in LARC and therefore upon further validation may be potentially used for patient selection in non-operative management strategies. Clinical trial information: NCT03503630 .

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Background: The dreaded bacterial infection by extended-spectrum β-lactamases (ESBL)-producers has always troubled the medical field whether on the public, scientific, or clinical levels. One of the lesser known β-lactamases, which is capable of hydrolyzing broad and extended-spectrum cephalosporins—i.e., cephamycins plus oxyimino-β-lactams—are the AmpC β-lactamases. This group, which has also been termed occasionally—and incorrectly—as ESBL Class C, confers resistance to β-lactamase inhibitors. The prevalence of plasmidic AmpC (pAmpC) strains is possibly still a matter of debate considering the unevenly matched data between phenotypically-detected and molecularly-detected pAmpC.Aim: In the absence of any study in Lebanon addressing the AmpC, our intention was to determine the numbers and percentages of AmpC Enterobacteriaceae isolates, notably plasmid-mediated ones, across different wards at the Centre Hospitalier du Nord (CHN), Lebanon, and highlight the importance of infection control protocols.Materials and Methods: Carriage and infection with pAmpC Enterobacteriaceae were retrospectively investigated between 2011 and 2015 and prospectively between 2016 and 2019 at the Centre Hospitalier du Nord Hospital, North Lebanon. The rise or decline in the numbers of such strains, in concordance with the allegedly intensive isolation of the patients, were analyzed.Results: Intensive care unit (ICU) data shows an initial rise in infection isolates from 2012 to 2014 and in the carriage isolates from 2012 to 2013 with later notable overall decrease in the both isolates' numbers with the application of the isolation protocols at CHN from 2014 onwards. Floors 2, 3, and 4 seemed to house the bulk of the isolates as well.Conclusion: Preventive measures, such as on-going surveillance of the hospital wards by specialized healthcare personnel and strict implementation of infection control practices, should be a top priority in any medical center in order to isolate such strains and try to put a limit for the development and the dissemination of any possible multidrug resistant strains.