Methods: This study aims to develop a recombinant anti-mKRAS scFv-fused mutant Hydra actinoporin-like-toxin-1 (mHALT-1) immunotoxin that is capable of recognizing and eradicating codon-12 mutated k-ras antigen abnormal cells. One G13D peptide mimotope (164-D) and one G12V peptide mimotope (68-V) were designed to elicit antigen specific IgG titres against mutated K-ras antigens in immunised Balb/c mice. The RNA was extracted from splenocytes following ELISA confirmation on post-immunized mice sera and was reverse transcribed into cDNA. The scFv combinatorial library was constructed from cDNA repertoire of variable regions of heavy chain (VH) and light chain (VL) fusions connected by a flexible glycine-serine linker, using splicing by overlap extension PCR (SOE-PCR). Anti-mKRAS G12V and G13D scFvs were cloned in pCANTAB5E phagemid and superinfected with helper phage. After few rounds of bio-panning, a specific mKRAS G12V and G13D scFv antibody against G12V and G13D control mimotope was identified and confirmed using ELISA without any cross-reactivity with other mimotopes or controls. Subsequently, the anti-mKRAS scFv was fused to mHALT-1 using SOE-PCR and cloned in pET22b vector. Expressed recombinant immunotoxins were analyzed for their effects on cell proliferation by the MTT assay and targeted specificity by cell-based ELISA on KRAS-positive and KRAS-negative cancer cells.
Results: The VH and VL genes from spleen RNA of mice immunized with 164-D and 68-V were amplified and randomly linked together, using SOE-PCR producing band sizes about 750 bp. Anti-mKRAS G12V and G13D scFvs were constructed in phagemid pCANTAB5E vectors with a library containing 3.4 × 106 and 2.9 × 106 individual clones, respectively. After three rounds of bio-panning, the anti-mKRAS G12V-34 scFv antibody against G12V control mimotope was identified and confirmed without any cross-reactivity with other controls using ELISA. Anti-mKRAS G12V-34 scFv fragment was fused to mHALT-1 toxin and cloned in pET22b vector with expression as inclusion bodies in E. coli BL21(DE3) (molecular weight of ~46.8 kDa). After successful solubilization and refolding, the mHALT-1-scFv immunotoxin exhibited cytotoxic effects on SW-480 colorectal cancer cells with IC50 of 25.39 μg/mL, with minimal cytotoxicity effect on NHDF cells.
Discussion: These results suggested that the development of such immunotoxins is potentially useful as an immunotherapeutic application against KRAS-positive malignancies.
Case presentation: We present a case of 15-year-old boy from rural area, presented with chronic diarrhea and per rectal bleeding for 3 months. The diagnosis was determined by colonoscope which revealed a fungating mass identified at 10cm from anal verge. Histological examination confirmed diagnosis of signet ring cell adenocarcinoma. CT scan of the abdomen showed thickening involving the recto-sigmoid colon and rectal mass, without evidence of distant metastatic disease. The patient's carcinoembryonic antigen level was within the normal range. He underwent a colostomy and was subjected to neoadjuvant CCRT and surgery.
Discussion: This CASE highlights the importance and challenges in achieving early diagnosis and surgical intervention of signet-ring cell carcinoma in adolescents, as most cases are detected at an advanced stage coupled with the scarcity of information on these rarer subtypes which leads to a poor prognosis.
Conclusion: In managing Signet cell carcinoma of the colorectal, physician have to know that it has a poor prognosis in patients of any age. However, in young teenagers delayed diagnosis and treatment option are narrowed to palliative management. Genetic profiling of family members and similar environment population may be a key to early detection.
Materials and methods: 3D-mediated inhibition on cell viability was evaluated by MTT and real-time cell proliferation was measured by xCelligence RTDP instrument. Western blotting was used to measure pro-apoptotic, anti-apoptotic proteins and JAK2-STAT3 phosphorylation. Flow cytometry was used to measure ROS production and apoptosis.
Results: Our study revealed that 3D treatment significantly reduced the viability of human CRC cells HT-29 and SW620. Furthermore, 3D treatment induced the generation of reactive oxygen species (ROS) in human CRC cells. Confirming our observation, N-acetylcysteine significantly inhibited apoptosis. This is further evidenced by the induction of p53 and Bax; release of cytochrome c; activation of caspase-9, caspase-7 and caspase-3; and cleavage of PARP in 3D-treated cells. This compound was found to have a significant effect on the inhibition of antiapoptotic proteins Bcl2 and BclxL. The results further demonstrate that 3D inhibits JAK2-STAT3 pathway by decreasing the constitutive and IL-6-induced phosphorylation of STAT3. 3D also decreases STAT3 target genes such as cyclin D1 and survivin. Furthermore, a combination study of 3D with doxorubicin (Dox) also showed more potent effects than single treatment of Dox in the inhibition of cell viability.
Conclusion: Taken together, these findings indicate that 3D induces ROS-mediated apoptosis and inhibits JAK2-STAT3 signaling in CRC.
MATERIALS AND METHODS: Here we reported the initial experience of aflibercept / FOLFIRI in combination. We evaluated treatment-related adverse events (AEs), progression-free survival (PFS) and overall survival (OS).
RESULTS: The majority of the patients experienced gastrointestinal toxicity (grade 1-2), with diarrhea (52%), mucositis (52%), and nausea/vomiting (20%) being largely observed. Neutropenia (16%) and febrile neutropenia (8%) were common grade 3-4 hematological events. Aflibercept-related toxicity was managed as per practice guidelines. No grade 5 event was reported. Median PFS was 6.12 months (95% CI, 4.80-7.20) and OS was 12 months (95% CI, 9.80-14.18). The partial response (PR), stable disease (SD), and progressive disease (PD) rates were 25% (95% CI: 23.4-27.0), 37.5% (95% CI: 31.6-43.3), and 37.5% (95% CI: 22.5-52.5), respectively.
CONCLUSIONS: Aflibercept/FOLFIRI can be administered safely in a second line setting to Malaysian patients with mCRC, as the AEs experienced were generally reversible and manageable. The safety and efficacy outcomes were consistent with those observed in Western populations.