Challenges presented by complete response to immune checkpoint blockade in patients with dMMR colorectal cancer: A case report.

INTRODUCTION: Early clinical trials have demonstrated remarkable responses to immune checkpoint blockade (ICB) in patients with colorectal cancers with deficient mismatch repair (dMMR) mechanisms. The precise role immunotherapy will play in the treatment of these patients is undefined, with these agents likely to produce new challenges as well as opportunities. PRESENTATION OF CASE: A 74-year-old patient was diagnosed with a locally advanced dMMR adenocarcinoma in the transverse colon with clinical suspicion of peritoneal metastases (cT4N2M1). The burden of disease was assessed as incurable, and a referral was made for palliative oncological treatment. After 5 months of treatment with pembrolizumab, a complete radiological response in the primary tumour was seen although there was still radiological suspicion of peritoneal and lymph node metastases. The patient underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy but unfortunately died 6 weeks later due to complications. Final histology of the surgical specimen showed no evidence of residual disease (ypT0N0M0). DISCUSSION: This case highlights the opportunities and challenges presented by the efficacy of ICB in dMMR colorectal cancer. These agents were able to cure a patient who had disseminated disease presumed to be incurable at the time of diagnosis. However, due to current limitations in determining the degree of response to ICB, this result could only be confirmed after major surgery, which ultimately led to the patient's death. CONCLUSION: ICB can lead to dramatic responses in patients with dMMR colorectal cancers. Major challenges remain in differentiating complete and partial responders and determining the indications for conventional surgery.

Therapy with pembrolizumab in treatment-naïve patients with nonmetastatic, mismatch repair deficient colorectal cancer.

Therapy with immune checkpoint inhibitors (ICI) is effective in patients with metastatic mismatch-repair deficient (dMMR) colorectal cancer (CRC); however, data on treatment with neoadjuvant ICI in patients with locally advanced CRC are limited. From March 2019 to June 2020, five Danish oncological centers treated 10 patients with a treatment-naïve dMMR CRC with preoperative pembrolizumab, 9 with a nonmetastatic, unresectable colon cancer and 1 with a locally advanced rectum cancer. All 10 patients were evaluated regularly at a multidisciplinary team (MDT) meeting, and they all had a radical resection after a median of 8 cycles (range 2-13) of pembrolizumab. A microscopic evaluation of the resected tumors revealed no remaining tumor cells in five patients, while five still had tumor cells present. The patients were given no additional therapy. No recurrences were reported after a median follow-up of 26 months (range 23-38.5 months). Biopsies from Danish patients with CRC are routinely screened for dMMR proteins. In 2017, data from the Danish Colorectal Cancer Group showed that 19% (565/3000) of the patients with colon cancer and 1.5% (19/1279) of those with rectum cancer had an dMMR tumor. Among the patients with MMR determination, 26% (99/384) patients had a T4 dMMR colon cancer; thus, the 10 patients treated with neoadjuvant pembrolizumab comprised about 9% of the patients with a T4 dMMR colon cancer (9/99) and 5% of patients with dMMR rectal cancer (1/19). Therapy with pembrolizumab was feasible and effective. Larger prospective trials are needed to confirm our findings.

Incidence of cold-induced peripheral neuropathy and dose modification of adjuvant oxaliplatin-based chemotherapy for patients with colorectal cancer.

BACKGROUND: The CAPOX regimen is used for adjuvant treatment of colorectal cancer. A well-known side effect of oxaliplatin, which often leads to dose modification (DM), is acute neuropathy (AN). AN is provoked by cold, and it could therefore be expected that the degree of AN and thereby DM is more pronounced in the winter period compared to the summer period. METHOD: Patients with colorectal cancer who received adjuvant CAPOX from January 2005 to August 2011 were reviewed. Out of 108 patients who received adjuvant CAPOX, the oxaliplatin dose was reduced in 92 (85%) patients due to AN. Seventeen out of 31 (55%) patients already had a DM of oxaliplatin in the second cycle during the winter period (December to February; mean temperature 0.1-1.8°C), while in the summer period (June to August; mean temperature 15.1-16.3°C), only 4 (13%) patients needed DM (OR = 2.5, p = 0.022). CONCLUSION: In this study, we found that the risk of DM and discontinuation of oxaliplatin is highest in the winter period compared to the other seasons. This study draws attention to the importance of training in the proper handling of the acute neurotoxicity of oxaliplatin.

Malignant pheochromocytomas and paragangliomas - the importance of a multidisciplinary approach.

Approximately 10% of the pheochromocytomas and 20% of the paragangliomas are malignant with poor survival. As the biological behaviour of these tumours cannot be predicted with certainty from pathology the diagnosis of malignancy is difficult. Genetic testing is gaining impact as mutations in the tumour suppressor gene Von Hippel-Lindau and the mitochondrial succinate dehydrogenase enzyme complex subunit B (SDHB) are associated with malignancy. Excess release of catecholamines is characteristic for pheochromocytomas. High levels of chromogranin A, that is co-stored and co-secreted with catecholamines, may indicate tumour mass and malignancy and can be used to monitor response and relapse. The secretory and non-secretory tumours can be visualised with functional (specific and non-specific) imaging as SPECT and PET using ¹²³I-MIBG, somatostatin analogues, ¹8F-DOPA, and ¹8F-FDG. These modalities are recommended in patients with extra-adrenal and suspected metastatic/malignant disease, in case of distorted post-operative anatomy, and when suspected recurrence. The sensitivities of ¹²³I-MIBG scintigraphy or ¹8F-DOPA PET are relatively low in SDHB mutated tumours, but high using ¹8F-FDG. Specific PET imaging with somatostatin analogues generally has high sensitivity in malignant disease. There are no curative therapeutic options for malignant, metastatic pheochromocytomas/paragangliomas, wherefore consolidation of quality of life is essential. Adjuvant radionuclide treatment with beta-emitting isotopes coupled to MIBG or somatostatin analogues have shown response in approximately 30%. Chemotherapy is restricted to patients not accessible for surgery and resistant to radionuclide therapy. Novel targeted therapies, which mainly through a cytostatic effect interfere with specific targeted molecules needed for carcinogenesis and tumour growth show encouraging results.