[Individualizing treatment for locally advanced rectal cancer]

The prognostic capacities of CBP and p300 in locally advanced rectal cancer

Background

CREB-binding protein (CBP) and p300 represent histone acetyltransferases (HATs) and transcriptional coactivators that play essential roles in tumour initiation and progression. Both proteins are generally thought to function as tumour suppressors, although their distinct roles in colorectal cancer (CRC) remain inconsistent and ambiguous.

Thus, we analysed the expression of these two HATs in human tissue samples from patients with locally advanced rectal cancer via immunohistochemistry and evaluated their potential impacts on future CRC diagnosis and treatment.

Methods

In our analysis, we included ninety-three (n = 93) patients diagnosed with adenocarcinoma in the upper third of the rectum. None of the patients received preoperative chemoradiotherapy, but the patients did undergo primary resection of the tumour within the phase II GAST-05 trial. By using H-scores, the expression of both proteins was visualised via immunohistochemistry in resected specimens from the patients. CBP and p300 expression were correlated with clinical and follow-up data.

Results

Our analysis showed that high expression of CBP was significantly associated with prolonged cancer-specific survival (CSS; p = 0.002). In univariate analysis, CBP was an independent prognostic parameter for CSS (p = 0.042). High nuclear CBP expression was observed in two-thirds of patients. In contrast, we could not find any significant correlation between the expression of p300 and cancer-specific survival in this cohort of patients (p = 0.09). We did not observe any cooperation between CBP and p300 in our analysis.

Conclusions

High expression of CBP was significantly associated with improved oncological outcomes. This finding could help to stratify patients in the future for CRC treatment. Histone deacetylase (HDAC) inhibitors are increasingly playing a role in oncological treatment and could additionally become therapeutic options in CRC. Our findings need to be further evaluated and verified in future clinical analyses.

Why take part in personalised cancer research? Patients' genetic misconception, genetic responsibility and incomprehension of stratification-an empirical-ethical examination

Therapeutic misconception is a well-known challenge for informed decision-making for cancer research participants. What is still missing, is a detailed understanding of the impact of "personalised" treatment research (e.g. biomarkers for stratification) on research participants. For this, we conducted the first longitudinal empirical-ethical study based on semi-structured interviews with colorectal cancer patients (n = 40) enrolled in a biomarker trial for (neo)adjuvant treatment, analysing the patients' understanding of and perspectives on research and treatment with qualitative methods. In addition to therapeutic misconception based on patients' confusion of research and treatment, and here triggered by misled motivation, information paternalism or incomprehension, we identified genetic misconception and genetic responsibility as new problematic issues. Patients mainly were not aware of the major research aim of future stratification into responders and non-responders nor did they fully acknowledge this as the aim for personalised cancer research. Thus, ethical and practical reflection on informed decision-making in cancer treatment and research should take into account the complexity of lay interpretations of modern personalised medicine. Instead of very formalistic, liability-oriented informed consent procedures, we suggest a more personalised communication approach to inform and motivate patients for cancer research.

Oxaliplatin-Induced Leukocytoclastic Vasculitis under Adjuvant Chemotherapy for Colorectal Cancer: Two Cases of a Rare Adverse Event

Leukocytoclastic vasculitis is a multicausal systemic inflammatory disease of the small vessels, histologically characterized by inflammation and deposition of both nuclear debris and fibrin in dermal postcapillary venules. The clinical picture typically involves palpable purpura of the lower legs and may be associated with general symptoms such as fatigue, arthralgia and fever. Involvement of the internal organs, most notably the kidneys, the central nervous system or the eyes, is possible and determines the prognosis. Oxaliplatin-induced leukocytoclastic vasculitis is a very rare event that limits treatment options in affected patients. We report 2 patients who developed the condition under chemotherapy for advanced rectal and metastatic colon carcinoma, respectively; a termination of the therapy was therefore necessary. While current therapies for colorectal cancer include the combination of multimodal treatment with new and targeted agents, rare and unusual side effects elicited by established agents also need to be taken into account for the clinical management.

Novel Carcinoembryonic-Antigen-(CEA)-Specific Pretargeting System to Assess Tumor Cell Viability after Irradiation of Colorectal Cancer Cells

PURPOSE

To date, no valid imaging modality exists for early response prediction to neoadjuvant radiochemotherapy in carcinoembryonic-antigen-(CEA)-expressing rectal cancers (UICC stages II and III). It is hypothesized that the uptake of an anti-CEA antibody is directly related to the number of viable tumor cells and may be quantified by immuno-positron emission tomography (immuno-PET). Therefore, we evaluated a novel pretargeting system using TF2, a humanized bispecific trivalent monoclonal antibody (mAb), directed against CEA and the IMP-288-peptide, a hapten for binding radiometals for imaging. Uptake and kinetics of the pretargeting system were investigated in vitro prior to and after irradiation.

METHODS

TF2 was labeled with ¹³¹I and IMP-288 with ¹¹¹InCl₃. The colorectal cancer cell lines HT29, SW480, and T84 with known varying CEA expression were incubated (≤ 72 hours) with ¹³¹I-TF2 or the TF2-¹¹¹In-IMP-288 pretargeting system. Parallel cultures were irradiated with 2-10 Gy high-energy photons. Tracer uptake, proliferation, apoptosis, and CEA-RNA expression of cancer cells were investigated.

RESULTS

The uptake of tracers was dependent on CEA expression and cell count of the cell lines (uptake/10⁶ cells: 0.3% in HT29, 1.5% in SW480, and 14% in T84, p < 0.001). The TF2-¹¹¹In-IMP-288 pretargeting system showed a higher uptake after 4 and 72 hours compared to (131)I-TF2 in parallel cultures. Only in one cell line (SW480) an increased apoptosis after irradiation could be detected. Irradiation increased dose dependently both the specific uptake of ¹³¹I-TF2 and of the TF2-¹¹¹In-IMP-288 system (4-fold in HT29 and T84 after 10 Gy (72 hours), p < 0.001). These results were CEA-mRNA independent.

CONCLUSION

This novel pretargeting system allows the quantitative analysis of CEA-expressing colorectal cancer cells and represents a promising tool for evaluation of tumor cell viability after irradiation.