The Narrow Path of Personalized Cancer Medicine

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Since I’m not directly involved in oncology care, I have a limited perspective on how quickly molecular medicine may transform cancer care.  A recent commentary (IF Tannock, JA Hickman. NEJM 2016; 1289-94) explains the “Limits to Personalized Cancer Medicine.”

While the idea of careful molecular characterization of tumors that lead to targeted therapy with better survival and better patient quality of life has been proven effective in several circumstances, there are a number of reasons why this approach will not be useful for most cancers.

Key points:

  • Examples of current personalized cancer Rx: trastuzumab for HER2-expressing breast cancer and vemurafenib for BRAF-mutated-expressing melanomas.
  • Very few studies have shown feasibility/effectiveness of targeted drug treatment
  • There has been limited success with targeted drugs within and outside studies
  • Though proponents of targeted therapy expect further advances, tumors typically have heterogeneity which allows a Darwinian evolution to evade these new therapies. “Cancer cells have an almost universal capacity to develop resistance to a single molecular targeted agent by means of upregulation of the partially inhibited pathway, mutation of the target, or activation of alternative pathways.”
  • Targeted therapies are usually limited by only partial inhibition of the signaling pathways and by toxicity when used in combination therapy.
  • In some cases, a clonal driver mutation may be present which would be present in all cell lines –however the authors note that success from this approach is likely to be rare.
  • Cost: “new drugs to treat cancer are marketed at ever-increasing prices…unrelated to value (i.e. to clinical effectiveness)….but the development and marketing of expensive drugs with marginal effectiveness diverts resources from the development of more effective therapies.”

My take (borrowed from authors): “The concept of personalized medicine is so appealing…[but] there should also be a clear message to patients that personalized cancer medicine has not led to gains in survival…and is an appropriate strategy only within well-designed clinical trials.”

Related blog post:

University of Virginia

The Lawn, University of Virginia

GI Educational Cartoons For Children

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Diana Lerner and the Medical College of Wisconsin have developed additional GI educational videos.  Previously, they had developed cartoon videos explaining endoscopy (prev post: Terrific Educational Videos on Endoscopy).  Now there are several more.  All of these are in English and some in Spanish.

Topics include inflammatory bowel disease, gastroesophageal reflux, eosinophilic esophagitis, and celiac disease.

Here’s the link:  Pediatric Gastroenterology Cartoons For Kids

Related blog post:

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October 2016: IBD Studies

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Briefly noted:

E Zittan et al. Inflamm Bowel Dis 2016; 22: 2442-47.  In this study with 773 patients with history of ulcerative colitis/ileal pouch-anal anastomosis, there was no significant difference in complications/leak among the 196 with preoperative anti-TNF exposure (n=26, 13.2%) compared with the control group (n=66, 11.7%). Preoperative anti-TNF exposure does not appear to worsen outcomes after surgery.

C Hartman et al. JPGN 2016; 63: 437-444. This cross-sectional survey of 68 children with IBD (57 Crohn’s disease) found frequent nutrient deficiencies based on 3 day diet records.  Interestingly, children on exclusive enteral nutrition were much less likely to have inadequate intakes of energy, minerals, or micronutrients. This article provides plenty of reasons for children with IBD, particularly Crohn’s disease, to work with a nutritionist.

M Fischer et al. Inflamm Bowel Dis; 2016; 22: 2402-09. In a cohort study of 67 patients (35 with Crohn’s, 31 with ulcerative colitis, and 1 indeterminate colitis), fecal microbiota transplantation (FMT) for refractory Clostridium difficile infection was successful in 53 (79%) with a single infusion.  Four of the 14 failures, subsequently responded to anti-CDI antibiotics. Of the 8 who had a 2nd FMT, 6 were successful; and 1 of 2 responded to 3rd FMT.  Thus, 60 of 67 responded overall to FMT.  After FMT, IBD disease activity was reported as improved in 25 (37%), no change in 20 (30%) and worse in 9 (13%).  In this cohort, 1 needed colectomy and 1 needed diversion.  This article indicates that FMT for CDI in IBD was associated with high cure rates and low risk of IBD flare.

A Khoruts et al. Clin Gastroenterol Hepatol 2016; 14: 1433-38. This was a study of 272 consecutive patients that underwent FMT for recurrent CDI. 15% had established IBD and 2.6% were determined to have IBD at time of FMT.  74.4% of IBD patients responded to a single FMT compared with 92.1% of patients without IBD.  More than one quarter of IBD patients experienced a clinical flare after FMT.

MA Conrad et al. Inflamm Bowel Dis; 2016: 22: 2425-31.  This review of early pediatric experience with vedolizumab in 21 subjects (16 with Crohn’s disease) identified a clinical response in 6/19 (31.6%) evaluable subjects at week 6 and 11/19 (57.9%) by week 22. Steroid-free remission was noted in 3/20 at 14 weeks (15%) and 4/20 (20.0%) at 22 weeks.  Overall, this shows a fairly low response rate to vedolizumab in this highly selected cohort.  Prospective pediatric studies of vedolizumab are needed to identify which patients are most likely to benefit.

University of Virginia Rotunda

University of Virginia Rotunda

 

Case Report: Management after Accidental Bolus of Parenteral Nutrition

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Fortunately, most mistakes do not result in long-lasting consequences.  The authors’ of a recent report  (JPEN J Parenter Enteral Nutr August 2016 vol. 40 no. 6 883-885) note a severe setback for a patient after accidental bolus of parenteral nutrition:

Here’s the abstract:

There is a paucity of data that exists regarding acute toxicity and management in the setting of parental nutrition (PN) overdose. We describe a case of a patient who received an accidental rapid bolus of PN and fat emulsion. She developed a seizure, metabolic acidosis, arrhythmias, myocardial ischemia, altered mental status, hypotension, and hypoxemia likely caused by elevated triglycerides, leading to a hyperviscosity syndrome. After failing standard therapy, she was successfully treated with a single-volume plasma exchange with resolution of symptoms. Fat emulsion or intravenous lipid emulsion and much of its safety have been recently described in its use as a rescue therapy in resuscitation from drug-related toxicity. Elevated serum triglyceride levels can result in a picture similar to a hyperviscosity syndrome. Plasma exchange is a known therapeutic modality for the management of hyperviscosity syndrome and a novel therapy in the treatment of hyperviscosity syndrome due to fat emulsion therapy. In a patient receiving PN with development of rapid deterioration of clinical status, without an obvious etiology, there should be consideration of PN overdose. A rapid assessment and treatment of severe electrolyte abnormalities should be undertaken immediately to prevent life-threatening cardiovascular and central nervous system collapse. If fat emulsion was rapidly coadministered and there are signs and symptoms of hyperviscosity syndrome, then consideration should be given to plasma exchange as an effective therapeutic treatment option.

Should We Care About Subclinical Primary Sclerosing Cholangitis with Inflammatory Bowel Disease?

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A recent study (AK Lunder et al. Gastroenterol 2016; 151: 660-69, editorial 590-3) provides more information about the prevalence of subclinical primary sclerosing cholangitis (PSC) in the setting of long-term inflammatory bowel disease. From a cohort of 756 Norwegian patients in the “IBSEN” cohort of patients with inflammatory bowel disease, the authors analyzed 327 patients with magnetic resonance cholangiography (MRC).

Key findings:

  • 24 (7.5%) of 327 patients who had been followed for 20 years were found to have PSC lesions.  Only 7 (2.2%) were known to have PSC based on biochemical or clinical features. Subsequently, a missed case of small-duct PSC was recognized increasing the rate to 8.1%.
  • Subclinical PSC, interestingly, was detected more often in Crohn’s patients (9.0%) compared with ulcerative colitis (6.8%)
  • Extensive colitis, high prevalence of colectomy, and refractory IBD symptoms were more common in patients with suspected PSC compared with those without PSC features (P= .029, P= .002, and P= .012 respectively)

The natural history of these subclinical cases of PSC is unclear.  Studies have shown that patients with PSC with normal alkaline phosphatase values have an excellent outlook.  Yet, there should be some concern.  PSC has been associated with 400-fold higher chance of cholangiocarcinoma and 5-fold increased risk of developing colorectal cancer.  This could indicate the need for more intensive surveillance in these patients –though the exact risks in those with subclinical disease is unknown.

My take: Until we know more, I doubt looking for subclinical PSC makes sense outside research protocols.

Related blog posts:

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Primary Sclerosing Cholangitis 2016

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Though this blog has reviewed primary sclerosing cholangitis (PSC), it has been a while since I’ve posted much.  As such, I thought I would place a post of a recent review (KN Lazaridis, NF LaRusso. NEJM 2016; 375; 1161-70).

Key points:

Epidemiology:

  • Strongly associated with inflammatory bowel disease with 70-80% of PSC patients having IBD
  • Median age at diagnosis 41 years with ~6-% male

Clinical manifestations:

  • Insidious disease in most.  “About half the patients with this condition do not have symptoms but receive a diagnosis after liver-function tests are found to be abnormal.”
  • Diagnostic criteria include increased alkaline phosphatase for more than 6 months
  • In adults, a liver biopsy is not need for diagnosis
  • Tends to be slowly progressive
  • Bacterial cholangitis is reported as initial presentation in ~6% and can be recurrent and intractable
  • Colon cancer is more frequent in patients with PSC.  “Colonoscopy is warranted in all patients who have received a new diagnosis”

Subtypes:

  • Classic subtype (90%) involves the entire biliary tree
  • ~5% have only small intrahepatic bile duct involvement
  • ~5% of adults have overlap syndrome with autoimmune hepatitis.  In children, overlap syndrome is present in ~35%.
  • There are numerous “secondary” PSC causes including AIDS-related cholangiopathy, amyloidoiss, eosinophilic cholangiopathy, histiocytosis X, IgG4-associated cholangitis, and sarcoidosis (most extensive list -see Table 1)

Pathogenesis:

  • The exact reasons remain unclear.  There are associations with environmental triggers but these have not been proven to be causally related.  For example, patients with PSC are more likely to consume steak or hamburger compared with controls and less likely to consume similar amounts of fish.
  • Due to its association with IBD, there are “microbiota hypothesis” to account for the aberrant cholangiocytic response.

psc-nejm

Treatment:

  • “As of this writing, no effective medical therapy exists.”
  • The authors detail eight potential treatments that are being studied: obeticholic acid, simtuzumab, 24-nor-ursodeoxycholic acid, an apical sodium-dependent bile acid transporter inhibitor (LUM001), a human monoclonal antibody that targets vascular adhesion protein 1 (BTT1023), oral vancomycin (NCT01802073 -pediatric trial), and fecal microbiota transplantation.
  • Management: includes managing varices in those with cirrhosis, following for benign and malignant biliary strictures, following for gallbladder disease (eg. polyps or masses), colon cancer surveillance (typically yearly screening), and managing metabolic bone disease.

Briefly noted: M Bramuzzo et al. JPGN 2016; 63: 259-64.  Using an Italian Pediatric IBD registry, the authors noted 6.8% of 677 patients had autoimmune liver disease: 61% with PSC and 33% with overlap syndrome.

Related blog posts:

 

 

Pouchitis -Not So Rare in Patients with FAP

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In their introduction (KP Quinn et al. Clin Gastroenterol Hepatol 2016; 14: 1296-1301), the authors state the following:  “Despite the widely held notion that pouchitis is a rare complication in FAP following IPAA, clinical experience at our institution suggests [it]…is underestimated.”

Methods: retrospective cohort study of all FAP patients who underwent IPAA (ileal ouch-anal anastomosis) from 1992-2015 at their institution (Mayo clinic), n=113.

Key findings:

  • 25 (22.1%) developed pouchitis with a mean time to pouchitis of 4.1 years.
  • Of the 25 who developed pouchitis, 72% had an acute course and 28% had a chronic course.

My take: While pouchitis does occur more commonly in IBD following IPAA, it does occur with FAP more frequently than previously described.

Related blog post:

funnycity-name

First-Hand Account: Living-Donor Liver Transplantation

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From NY Times: Donating an Organ to My Son

An excerpt:

It has been a year and half since the surgery. Sammy looks great and is on minimal medication. He goes to school full time, and most people have no idea what he went through. The scar on his abdomen has mostly faded, and we aren’t sure if he even has any memories of this experience.

My liver has grown to full size and my scars are nearly invisible. But that doesn’t mean I am entirely recovered. There are moments, and they are less frequent and further between, that I get spontaneously choked up. This experience was both frightening and inspiring. I had to briefly give up being both doctor and a mother to become a patient. It was as a living donor that I was able to help my son the most.

Another comic account of living liver donation:

Chattahoochee River

Chattahoochee River

AAP Recommendations on Preventing Obesity and Eating Disorders

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From AAP Committee on Nutrition, Pediatrics, August 2016Full text: Preventing Obesity and Eating Disorders in Adolescents

  1. Discourage dieting, skipping of meals, or the use of diet pills; instead, encourage and support the implementation of healthy eating and physical activity behaviors that can be maintained on an ongoing basis. The focus should be on healthy living and healthy habits rather than on weight.
  2. Promote a positive body image among adolescents. Do not encourage body dissatisfaction or focus on body dissatisfaction as a reason for dieting.
  3. Encourage more frequent family meals.
  4. Encourage families not to talk about weight but rather to talk about healthy eating and being active to stay healthy. Do more at home to facilitate healthy eating and physical activity.
  5. Inquire about a history of mistreatment or bullying in overweight and obese teenagers and address this issue with patients and their families.
  6. Carefully monitor weight loss in an adolescent who needs to lose weight to ensure the adolescent does not develop the medical complications of semistarvation.
Gardens at University of Virginia

Gardens at University of Virginia

Nonsteroidal Analgesics and Risk of Empyema

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A recent study (M Le Bourgeois et al. J Pediatr 2016; 175: 47-53) from 15 medical centers in France showed an association between nonsteroidal anti-inflammatory drugs (NSAIDs) and the development of empyema.

Methods: a case-control design with 83 cases of children with empyema and recent acute viral infection (w/in 15 days) and 83 controls who had recent acute viral infection but no emyema. Age range: 3 months-15 years.  To ascertain the underlying initial viral etiology, the investigators utilized molecular techniques and identified respiratory viruses in about half of both groups of children.

Key finding: Exposure to NSAIDs was associated with a modest increase in the rate of empyema (aOR 2.79).  The risk of empyema associated with NSAIDs was diminished if the  child had been prescribed an antibiotic.

My take: This study, by minimizing confounding factors, suggests that the casual use of NSAIDs during acute viral illnesses increases the chance of developing empyema.

 

Grinnell Glacier, Glacier Nat'l Park

Grinnell Glacier, Glacier Nat’l Park