Alpha-gal syndrome develops in some individuals who have had tick bites which result in IgE responses to alpha-gal, a carbohydrate not found in humans. Patients with alpha-gal syndrome develop symptoms when they ingest mammalian meat, which contains this oligosaccharide. Often the response to this exposure is delayed and occurs 2 to 6 h post-ingestion. Symptoms can include skin rashes, urticaria, gastrointestinal symptoms, and occasionally anaphylaxis. In some patients, the initial site of the skin reaction is at the location of the prior tick bite. The frequency of the syndrome is uncertain but the geographic distribution is predominantly in areas with the lone star tick. The diagnosis depends on careful attention to the time interval between the ingestion of meat and the development of the symptoms. In addition, a history of prior tick bites is important for considering this diagnosis. Diagnostic studies include skin tests, serologic tests for specific IgE, and food challenges, with varying risks for anaphylaxis. The treatment of patients with acute presentations frequently includes intramuscular epinephrine, oral antihistamines, and corticosteroids. Long-term management involves diet modification with the elimination of meat. Patients can also have adverse reactions to medications, such as set cetuximab, heparin, monoclonal antibodies, and pancreatic enzymes, and clinicians will likely have difficulty identifying these reactions. If patients have a good response to diet modification and have a significant reduction in their specific IgE level to alpha-gal, they potentially can resume eating meat in their diet. This should be done under the direction of a specialist.
We present a case of a male in his 60s with a history of alpha-gal syndrome (AGS) who presented with recurrent acute colonic pseudo-obstruction, also known as Ogilvie syndrome, and underwent surgical treatment for life-limiting symptoms of colonic distention, constipation, and abdominal pain. Prior to surgery, he was hospitalized multiple times after beef consumption and was diagnosed with Ogilvie syndrome, requiring a colonoscopy with rectal tube placement for symptom resolution. He later underwent a robotic subtotal colectomy with ileocolic anastomosis. Follow-up visits showed improvement in symptoms of constipation and abdominal distention. This case highlights that AGS may lead to severe manifestations, such as recurrent Ogilvie syndrome. Due to the increasing prevalence of AGS and limited data on disease course, further research is needed to determine symptom manifestations and the potential utility of surgery in management.
Treatment of metastatic colorectal disease has evolved over the last decade. Two epidermal growth factor receptor (EGFR) monoclonal antibodies--cetuximab and panitumumab--have been developed in an effort to provide yet another therapeutic option. The EGFR is a transmembrane glycoprotein, expressed constitutively throughout the body and found on many epithelial tissues. The monoclonal antibodies bind to and inhibit the activation of the receptor in the body. This inhibition prevents tumor cell growth, angiogenesis, invasion, and metastasis, and induces apoptosis. Cetuximab and panitumumab exhibit nonlinear pharmacokinetics. Both monoclonal antibodies are approved for the treatment of refractory metastatic colorectal cancer. Cetuximab in combination with irinotecan has significantly better response rates and progression-free survival compared with those of cetuximab or irinotecan alone. Cetuximab and panitumumab as monotherapy have shown significantly better response rates and progression-free survival compared with best supportive care in patients refractory to irinotecan and oxaliplatin. In the Cetuximab Combined with Irinotecan in First Line Therapy for Metastatic Colorectal Cancer (CRYSTAL) trial, treatment-naïve patients received cetuximab in combination with the chemotherapy regimen infusional leucovorin, fluorouracil, and irinotecan (FOLFIRI) or FOLFIRI alone; the difference in progression-free survival was statistically significant but suggested only a modest benefit over FOLFIRI alone (8.9 vs 8 mo, p=0.036). Results of a preplanned analysis of the first 231 events in the Panitumumab Advanced Colorectal Cancer Evaluation (PACCE) trial favored the control group (chemotherapy regimen with folinic acid [leucovorin], fluorouracil, and oxaliplatin [FOLFOX] plus bevacizumab) instead of the control group plus panitumumab. For clinical consideration, many trials have shown that the intensity or absence of EGFR expression is not a clinically significant predictor of outcomes. Development and intensity of a rash are suggested to be a positive predictor of outcomes in patients. The most common adverse events of EGFR monoclonal antibody therapy are rash, diarrhea, and hypomagnesemia. Other serious but not common adverse events include hypersensitivity reactions and pulmonary toxicity. The availability of EGFR monoclonal antibodies has provided another weapon in the arsenal to treat refractory metastatic colorectal cancer. They have shown safety and efficacy in combination with other chemotherapy regimens and as monotherapy; however, their use as metastatic colorectal cancer therapy needs to be further explored.
