In the News, New Cystic Fibrosis Study

More information related to today’s earlier post: In the News: Big Therapeutic Advance for Cystic Fibrosis

Abstract

BACKGROUND

Cystic fibrosis is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, and nearly 90% of patients have at least one copy of the Phe508del CFTR mutation. In a phase 2 trial involving patients who were heterozygous for the Phe508del CFTR mutation and a minimal-function mutation (Phe508del–minimal function genotype), the next-generation CFTR corrector elexacaftor, in combination with tezacaftor and ivacaftor, improved Phe508del CFTR function and clinical outcomes.

METHODS

We conducted a phase 3, randomized, double-blind, placebo-controlled trial to confirm the efficacy and safety of elexacaftor–tezacaftor–ivacaftor in patients 12 years of age or older with cystic fibrosis with Phe508del–minimal function genotypes. Patients were randomly assigned to receive elexacaftor–tezacaftor–ivacaftor or placebo for 24 weeks. The primary end point was absolute change from baseline in percentage of predicted forced expiratory volume in 1 second (FEV1) at week 4.

RESULTS

A total of 403 patients underwent randomization and received at least one dose of active treatment or placebo. Elexacaftor–tezacaftor–ivacaftor, relative to placebo, resulted in a percentage of predicted FEV1 that was 13.8 points higher at 4 weeks and 14.3 points higher through 24 weeks, a rate of pulmonary exacerbations that was 63% lower, a respiratory domain score on the Cystic Fibrosis Questionnaire–Revised (range, 0 to 100, with higher scores indicating a higher patient-reported quality of life with regard to respiratory symptoms; minimum clinically important difference, 4 points) that was 20.2 points higher, and a sweat chloride concentration that was 41.8 mmol per liter lower (P<0.001 for all comparisons). Elexacaftor–tezacaftor–ivacaftor was generally safe and had an acceptable side-effect profile. Most patients had adverse events that were mild or moderate. Adverse events leading to discontinuation of the trial regimen occurred in 1% of the patients in the elexacaftor–tezacaftor–ivacaftor group.

CONCLUSIONS

Elexacaftor–tezacaftor–ivacaftor was efficacious in patients with cystic fibrosis with Phe508del–minimal function genotypes, in whom previous CFTR modulator regimens were ineffective. (Funded by Vertex Pharmaceuticals; VX17-445-102 ClinicalTrials.gov number, NCT03525444. opens in new tab.)

In the News: Big Therapeutic Advance for Cystic Fibrosis

Washington Post: Long-Awaited Drug Could Turn Deadly Disease into Manageable Condition

An excerpt:

A new cystic fibrosis therapy dramatically improved patients’ lung function and showed clear signs of targeting the genetic root of the disease, instead of just alleviating symptoms — a breakthrough so long-sought that many doctors and patients are moved to tears when talking about it.

The data, being unveiled Thursday at a national conference in Tennessee and simultaneously published in two leading medical journals, was so persuasive that the Food and Drug Administration last week approved the three-drug combination, called Trikafta — five months ahead of the agency’s deadline. The drug could benefit 90 percent of patients with the disease, a major advance over previous drugs that worked in a tiny fraction of the people with the disease or had more modest effects

Sarah Carollo, 28, a special needs teacher in Lee’s Summit, Mo., started Trikafta through a clinical trial in late 2018. Carollo… couldn’t walk down a hallway without stopping to rest and catch her breath…

A few days after she began taking the pill, her doctors tested her lung function and were so stunned at the improvement that they had to check whether they were really looking at the results from the right patient. Two weeks ago, Carollo ran a 5K race with another patient, Laurana Blackburn, who was also taking the drug through the clinical trial…

There are more than 1,700 gene mutations that can cause the protein to malfunction, but in the most common mutation, the protein is misfolded and can’t reach the right spot in the cell — and even if it does reach that spot, it doesn’t work properly. The new combination therapy includes one drug that corrects the misfolded protein and two that activate the correctly folded protein when it reaches the right spot in the cell.

In the largest trial, reported in the New England Journal of Medicine, 403 patients who had at least one copy of the most common gene mutation underlying cystic fibrosis received either Trikafta or a placebo. There were improvements in objective tests of lung function, decreases in lung problems and hospitalizations and an increase in people’s quality of life…

It also remains to be seen whether patients have an easy time gaining access to the drug, which will cost $311,000 a year. While that is a tremendous amount, orphan drugs for small patient populations typically carry very large price tags, and physicians are optimistic that insurers will cover the drug.

The NY Times reported on the FDA approval (October 2019), Studies Yield ‘Impressive’ Results in Fight Against Cystic Fibrosis, and noted that the “Institute for Clinical and Economic Review, which evaluates the cost-effectiveness of drugs, found that the cystic fibrosis drugs the company sells should cost as much as 77 percent less. ”

#NASPGHAN19 Postgraduate Course (Part 2)

Here are some selected slides and notes from this year’s NASPGHAN’s postrgraduate course. My notes from these lectures may contain errors of omission or transcription.

Link to the full NASPGHAN PG Syllabus 2019 (Borrowed with permission)

9:00 – 10:20 “Potpourri”

46 Alessio Fasano, MD, MassGeneral Hospital for Children  Celiac disease: Beyond diagnosis

  • Reviewed potential non-biopsy option for diagnosis if anti-TG2 >10 x normal. Pediatricians are not following recommendations –>many children placed on gluten-free diet at lower titer antibody-positivity.
  • Recommends checking Hepatitis B antibody because many children with celiac disease do not seroconvert.
  • TTG levels are good for diagnosis but not as helpful for monitoring after diagnosis.
  • Only 10 out of 1000 are true refractory, about 100 out of 1000 are exquisitely sensitive to gluten

56 Meghana Sathe, MD, UT Southwestern Medical Center The role of the gastroenterologist and hepatologist in Cystic Fibrosis (CF) care today

  • Fecal elastase monitoring useful for determining need for PERT.
  • Discussed CF liver involvement.  Multilobular cirrhosis, 7% of individuals, is most important liver disease in CF.
  • Modulator therapy can elevate liver enzymes and may need to hold if ALT >5 ULN or lower elevation if elevated bilirubin (see Stop Rules -Practical Advice on DILI)
  • DIOS -for partial obstruction, polyethylene glycol and/or gastrogastrin enemas could be used.
  • Consider treatment of SBBO as well which is frequent with CF.

67 Sonia Michail, MD, Children’s Hospital Los Angeles Update on C. difficile

The slide I liked the best was showing a change in microbiome after FMT which is not in syllabus.

82 Ed Hoffenberg, MD, Children’s Hospital Colorado  What the pediatric GI provider needs to know about cannabis

Disclaimer: NASPGHAN/gutsandgrowth assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. The discussion, views, and recommendations as to medical procedures, choice of drugs and drug dosages herein are the sole responsibility of the authors. Because of rapid advances in the medical sciences, the Society cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure. Some of the slides reproduced in this syllabus contain animation in the power point version. This cannot be seen in the printed version.

PEG Placement in Cystic Fibrosis

A small retrospective study (RT Khalaf et al.NCP 2018; LINK: doi.org/10.1002/ncp.10219) showed that PEG placement was associated with a trend (not statistically significant) towards improved lung function in children with cystic fibrosis (CF). Reference from Kipp Ellsworth twitter feed.  There were 20 patients who had PEG placed compared to 40 patients who did not.

Findings:

  • BMI percentile increased per month for those with PEG (0.51, 95% confidence interval (CI) = −0.05–1.08, P = .08), but decreased for those without PEG (−0.03, 95% CI = −0.33–0.28, P = .86); however, the difference (0.54; 95% CI = −0.10–1.18, P = .10) was not statistically significant.
  • FEV1 change with time showed a decrease for patients with PEG (−0.04; 95% CI = −0.30–0.22, P = .74) and those without PEG (−.22; 95% CI = −0.45–0.01, P = .06). Although the FEVdecrease for those without PEG was higher than those with PEG, the difference between the groups was not statistically significant (0.18; 95% CI = −0.17–0.52, P = .32)

My take: While the differences are not statistically-significant, this study indicates that PEG placement is NOT detrimental to lung function in CF and may be beneficial.

Related blog posts:

Near Banff

Big Advance in Cystic Fibrosis –Who Will Benefit?

Recent studies point to huge advances in cystic fibrosis (CF) therapy. Though as noted in a previous blog (Why Do Canadians with Cystic Fibrosis Live Longer?), medical advances may have limited effect based on a lot of issues including access to care.

Despite that note of caution, it is hard not to be excited about a couple of recent publications which show that triple cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy has great potential to improve outcomes for CF patients.

  • JC Davies et al. NEJM 2018; 379: 1599-611.
  • D Keating et al. NEJM 2018; 379: 1612-20.
  • Editorial: F Holguin, 1671-2

Background: In the editorial, the pathophysiology of the defect of CF is discussed and how the newer medicines either act as a potentiator of the CFTR (ivacaftor) or as corrector (lumacaftor and tezacaftor).  Potentiators increase CFTR channel opening at the cell surface whereas correctors increase the amount of CFTR protein at the cell surface. One caveat has been that these therapies had not been proven effective, individually, for Phe508del CFTR mutation which occurs in “approximately two thirds of patients.”  Combination therapy has helped in most of this group but not in those with Phe508del-minimal function (MF).

The new studies examine triple therapy with the addition of two new-generation small molecule correctors: VX-445 and VX-659. These new correctors target different sites of the CFTR protein.

Key findings:

  • in the Davies (VX-659) trial, “4 weeks of triple therapy …increased the primary end point of predicted percentage of FEV1, in the Phe508del-MF and Phe508del-Phe508del groups by an averae of 13.3% and 9.7% respectively”
  • In the Keating (VX-445) trial, triple therapy “significantly increased FEV1 in patients with those genotypes by 13.8% and 11.0% respectively.”
  • Overall, triple therapy “improved the percentage of predicted FEV1 more than double-combination therapy” in patients with a Phe508del-Phe508del mutation.  And reported efficacy in the patients with Phe508del-MF CFTR mutation.
  • The majority of patients had at least one adverse event. 3 of the 122 in the VX-445 trial discontinue treatment due to severe adverse events.

My take: These reports “represent a major breakthrough…for improving health and possibly survival in all patients who carry the most common CFTR mutation.”  Long-term outcomes will need to be followed to confirm these findings.

Related blog posts:

This is Figure 2 from Davies study showing immunoblot findings, densitometry findings, and chloride transport in bronchial cells. The most robust responses were with triple therapy

 

Screening for Colorectal Cancer in Cystic Fibrosis

Briefly noted:

A Gini, et al. “Cost Effectiveness of Screening Individuals with Cystic Fibrosis for Colorectal Cancer” Gastroenterol 2018; 154: 556-67.

  • Key point: “Colonoscopy every 5 years, starting at age of 40 years was the optimal colonoscopy strategy for patients with cystic fibrosis” without prior organ transplantation.

D Hadjuliais, et al. “Cystic Fibrosis Colorectal Cancer Screening Consensus Recommendations: Gastroenterol 2018; 154: 736-45.

  • There are 10 Task Force recommendations. These include “initiation of screening at 40 years” in those without organ transplantation. Among those who have had organ transplantation, CRC screening is recommended at age 30 years and/or within 2 years of transplantation. Link: Abstract

My take: Fortunately, more individuals with cystic fibrosis are living long enough to benefit from CRC screening.  Due to increased risk, these guidelines recommend screening at a younger age than the general population.

More pics from Hoover Dam. The figure in this picture is a art piece honoring those who died while working on the construction

 

CFTR Modulators for Cystic Fibrosis

Two more studies have shown the effectiveness of CFTR modulators for subsets of patients with cystic fibrosis.

  • JL Taylor-Cousar et al. NEJM 2017; 377: 2013-23
  • SM Rowe et al. NEJM 2017; 377: 2024-35.

In the Taylor-Cousar study, the authors treated patients with homozygous Phe508del cystic fibrosis with either combination tezacaftor-ivacaftor or placebo for 24 weeks. Combination therapy resulted in FEV1 that was 4% higher along with a 35% lower rate of pulmonary exacerbations than placebo.

In the Rowe study which examined patients some retained CFTR function (which occurs ~5% of CF patients), a prospective trial of tezacaftor-ivacaftor had a greater effect on increasing FEV1 than ivacaftor alone.  Ivacaftor monotherapy and tezacaftor-ivacaftor combination therapy were both more effective than placebo.

A related editorial (H Grasemann. pgs: 2085-8) helps provide context to help understand the importance of these studies.  His key point:

“Although CFTR modulator therapies have measurable beneficial effects on some aspects of the disease, there is still an unmet need for truly effective new therapies to be developed for all persons with cystic fibrosis.  The clinical efficacy of the current combination therapies for patients with cystic fibrosis who have the most common CFTR genotype (Phe508del/Phe508del) is suboptimal and falls within the range of established symptomatic therapies, such as nebulized inhaled hypertonic saline or recombinant human DNAse.”

This figure depicts the types of molecular defects: No functional CFTR with framshifts for deletions or insertions (class 1), CFTR trafficking defect due to misfolded protein (class II), defective channel regulation (class III), reduced cholirde conductance (class IV) , reduced synthessis (class V) or decreased CFTR stability (class VI)