Sanofi Pasteur SA Pharmaceutical company announced on Friday, December 1, 2017 that it had ended development of an experimental vaccine for Clostridium difficile infection, after an early look at late-stage trial results indicated a low probability for success.
About three million Americans are infected annually with the bacterium – also known as C. diff – ———
The move marks the second blow in a week to Sanofi’s vaccine program after the Paris-based company on Wednesday said use of its new dengue vaccine will be strictly limited due to evidence it can worsen the disease in people who have not previously been exposed to the mosquito-borne virus.
Sanofi’s Dengvaxia vaccine is the world’s first approved shot for preventing dengue infection, which kills about 20,000 people a year and infects hundreds of millions.
The company said in a statement that all data from vaccinated volunteers in the C. diff trial will continue to be analyzed for more information and shared with the scientific community.
As many as 30,000 Americans die each year from the bacterium, usually after recurrences of infection. The infections are typically the result of taking antibiotics, which wipe out friendly bacteria in the colon that normally keep C. diff under control.
Sanofi said it will continue to focus on six other vaccine projects in development.
To view article in its entirety please click on the following link:
Ribaxamase is associated with reduced risk for new, opportunistic Clostridium difficile infections (CDI) in hospital patients, according to findings from a multinational, double-blind, placebo-controlled Phase 2b study presented at IDWeek 2017.
“These data support that ribaxamase can maintain the balance of the gut microbiome and thereby prevent opportunistic infections like CDI during IV beta-lactam treatment,” said lead study author John Kokai-Kun, PhD, of Synthetic Biologics, Inc., Rockville, MD.
“Ribaxamase also protected the diversity of the gut microbiome and reduced the emergence of antibiotic resistance in ceftriaxone-treated patients,” he said.
CDI represent an “urgent threat” but there are no FDA-approved drugs or vaccines to prevent infections, Dr. Kokai-Kun noted.
“SYN-004 (ribaxamase) is a beta-lactamase designed to be orally administered with IV beta-lactam antibiotics and remain localized in the intestine to degrade antibiotics excreted into the intestine,” he said. “This is expected to protect the gut microbiome from disruption thus preventing deleterious effects including, CDI, colonization by opportunistic pathogens and emergence of antibiotic resistance in the gut microbiome.”
“Ribaxamase was well tolerated and not systemically absorbed in Phase 1 studies and efficiently degraded ceftriaxone excreted into the human intestine while not altering the plasma pharmacokinetics of ceftriaxone in Phase 2a studies,” he told the IDWeek audience.
The researchers conducted their study to assess if ribaxamase prevents new-onset CDI. They also assessed non-CDI antibiotic-associated diarrhea, colonization by opportunistic pathogens, gut microbiome alterations and acquired antibiotic resistance.
Data from 412 patients (man age 70 years) in the intention-to-treat population “enriched for higher risk for CDI” were hospitalized for ≥5 days of IV ceftriaxone for treatment lower respiratory tract infections,” Dr. Kokai-Kun said. Patients were randomly assigned 1:1 to receive oral ribaxamase 150mg four times daily or placebo during IV ceftriaxone treatment and for an additional 72 hours.
“Fecal samples were collected at pre-specified points for determination of colonization by opportunistic pathogens and to examine changes in the gut microbiome,” Dr Kokai-Kun said. Patients were monitored for 6 weeks for CDI, defined as diarrhea plus the presence of C. difficile toxin.
Study participants saw a 71% relative risk reduction in CDI (P=0.045) and a statistically significant 44% relative risk reduction in new colonization by vancomycin-resistant enterococci (P=0.0002). Moreover, the respiratory infection was cleared in ~99% of cases demonstrating that concomitant ribaxamase did not impact the cure rate of ceftriaxone.
For continuous infectious disease news coverage from the IDWeek 2017, check back to MPR’s IDWeek page for the latest updates.
Kokai-Kun J, Roberts T, Coughlin O, Whalen H, Le C, Da Costa C, Sliman J. SYN-004 (ribaxamase) prevents New Onset Clostridium difficile Infection by Protecting the Integrity Gut Microbiome in a Phase 2b Study. Poster presented at IDWeek; October 4–8, 2017; San Diego, CA. http://www.idweek.org/.
On the other hand, the benefit of what Anderson called “enhanced terminal disinfection” varied among the four pathogens, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE), multidrug-resistant (MDR) acetinobacter, and Clostridium difficile.
What was the BETR-D Study?
The BETR-Disinfection study was performed over 28 months in 9 study hospitals from 4/2012 to 7/2014.
Each hospital used four strategies for terminal room disinfection in a randomized sequence.
Each strategy was used for 7-month study arms, including a 1 month wash-in period.
Two of these strategies used a UV-C emitting device.
Standard cleaning involved the use of a quaternary ammonium (reference group A). Three enhanced cleaning strategies were evaluated and compared to the reference: quaternary ammonium + UV-C (B), bleach (C), and bleach + UV-C (D).Of note, bleach was used for daily and terminal disinfection of all known C. difficile rooms, regardless of study arm.
Study cleaning strategies were employed in seed rooms, defined as a room containing a patient on contact precautions for infection or colonization due to the following 4 target MDROs was discharged: MRSA, VRE, C. difficile, or MDR Acinetobacter.
The next patient in the room was considered an exposed patient.
Primary outcome was the clinical incidence of all target MDROs in patients exposed for at least 24 hours, defined as the first positive culture of a MDRO a) during exposure to the seed room, if positivity occurred ≥48 hr post-admission to the seed room, or b) in the 90 days following seed room exposure for MRSA, VRE, and MDR-Acinetobacter and 28 days for C. difficile.
Rates were calculated as outcome/10,000 exposure days using intention-to-treat and per protocol principles
To read the study Abstract in its entirety please click on the following link:
A study of a large cluster-randomized trial, adding bleach to the standard quaternary ammonium cleaning significantly reduced the risk of transmission of four organisms that cause healthcare-associated infections
A Cluster Randomized, Multicenter Crossover Study with 2×2 Factorial Design to Evaluate the Impact of Enhanced Terminal Room Disinfection on Acquisition and Infection Caused by Multidrug-Resistant Organisms (MDRO)
The goal was to see if they could reduce the overall incidence of the targeted pathogens among patients using a room immediately after a patient known to be colonized or infected by one of the four occupied it. A second primary endpoint was the effect on C. difficile.
He noted that all rooms in which a patient had had C. difficile were cleaned with bleach, so the comparisons were actually between quaternary ammonium and bleach and the same approach adding UV light.
All told, the study had 23,272 patients potentially exposed to a pathogen — they spent at least 24 hours in one of the “seed” rooms where the previous patient had been identified as having one of the pathogens.
Patients in seed rooms became cases if they developed colonization or infection by the pathogens linked to their rooms, as long as they had no history of the pathogen in the previous year and no evidence of community acquisition, he said.
In the four arms, Anderson reported:
There were 115 cases in 22,426 exposure days in the standard cleaning arm, for a rate of 51.3 cases per 10,000 exposure days.
In the arm adding ultraviolet, there were 76 cases in 22,389 exposure days for a rate of 33.9
When bleach was added, there were 101 cases in 24,261 exposure days, for a rate of 41.6.
And when both bleach and UV were added, there were 131 cases in 28,757 exposure days, for a rate of 45.6.
The reductions, compared with standard cleaning, were 30%, 15% and 9%, respectively, but only the addition of UV light to quaternary ammonium reached statistical significance (P=0.036).
There were too few cases of MDR acetinobacter to quantify, he said, but it was possible to judge the effect of the various interventions on the other three pathogens.
For MRSA, adding UV light to quaternary ammonium reduced the risk of transmission by 22%, but the difference from standard cleaning fell short of statistical significance. The other two interventions made no difference.
For VRE, on the other hand, all three test strategies reduced the risk of transmission by about 60% — 59% for UV, 57% for bleach, and 64% for bleach plus UV. However, Anderson said, the UV arm was just short of statistical significance, while the other two were significantly different from standard cleaning (P=0.049 and P=0.003, respectively).
But adding UV light to bleach in rooms linked to C. difficile had no effect, Anderson reported.
Note: Not all UV disinfecting products are the same– in the way they are scientifically developed, manufactured, and utilized in the healthcare industry. It is favorable for Hospital and Healthcare facility decision-makers to ask some tough questions when it comes to evaluating UV technologies. The gold standard for assessing new technologies is to evaluate peer-reviewed literature published and also cited in The Lancet publication. Please click on the The Lancet article link below to retrieve additional information focused on the BETR-D study.
31 226 patients were exposed; 21 395 (69%) met all inclusion criteria, including 4916 in the reference group, 5178 in the UV group, 5438 in the bleach group, and 5863 in the bleach and UV group. 115 patients had the primary outcome during 22 426 exposure days in the reference group (51·3 per 10 000 exposure days). The incidence of target organisms among exposed patients was significantly lower after adding UV to standard cleaning strategies (n=76; 33·9 cases per 10 000 exposure days; relative risk [RR] 0·70, 95% CI 0·50–0·98; p=0·036). The primary outcome was not statistically lower with bleach (n=101; 41·6 cases per 10 000 exposure days; RR 0·85, 95% CI 0·69–1·04; p=0·116), or bleach and UV (n=131; 45·6 cases per 10 000 exposure days; RR 0·91, 95% CI 0·76–1·09; p=0·303) among exposed patients. Similarly, the incidence of C difficile infection among exposed patients was not changed after adding UV to cleaning with bleach (n=38 vs 36; 30·4 cases vs 31·6 cases per 10 000 exposure days; RR 1·0, 95% CI 0·57–1·75; p=0·997).
The BETR-D study was supported by the CDC
Listen to Deverick J. Anderson, MD, MPH, FIDSA, FSHEA discuss UV Intervention Addressing C. difficile and Other Pathogens July 2016
Pfizer Announces Positive Top-Line Results from Phase 2 Study of Investigational
Clostridium difficile Vaccine for the
Prevention of C. difficile Infection
Pfizer’s C. difficile Vaccine Candidate to Commence Phase 3 Study in First Half of 2017
C. difficile is an Increasing Worldwide Concern Associated with Approximately 29,000 Annual Deaths in the U.S. Alone
On Thursday, January 26, 2017 Pfizer Inc. announced that the Phase 2 study
evaluating the Company’s Clostridium difficile (C. difficile) vaccine
candidate, PF-06425090, provided positive data, based on a pre-planned interim analysis.
The randomized Phase 2 study (NCT02561195) examined the safety, tolerability, and immunogenicity of the vaccine in healthy adults 65 to 85 years of age. Pfizer’s vaccine candidate is designed to help prevent C. difficile infection (CDI), which can include life-threatening diarrhea and pseudomembranous colitis,1 by inducing a functional antibody response capable of neutralizing the two main disease-causing toxins produced by C. difficile (toxins A and B).2
“Despite improved infection control measures, C. difficile disease continues to rise, further augmenting an already urgent public health threat with particular negative impact on older adults,” said Kathrin Jansen, Ph.D., senior vice president and head of Vaccine Research and Development for Pfizer Inc. “We are very encouraged by these interim immunogenicity and safety results demonstrating robust increases in vaccine-elicited neutralizing antibodies to both toxins, that we believe could provide protection against C. difficile disease.”
Based on findings from the pre-planned interim analysis, Pfizer’s C. difficile vaccine candidate will progress into Phase 3 in the first half of 2017.
Pfizer’s C. difficile vaccine candidate was granted Fast Track designation by the U.S. Food and Drug Administration (FDA) in August 2014. The FDA’s Fast Track designation is designed to facilitate the development and expedite the review of new drugs and vaccines intended to treat or prevent serious conditions and address an unmet medical need.3 About the Phase 2 Study The Phase 2 study (NCT02561195) was a randomized, placebo-controlled, observer-blinded study of more than 850 healthy adults 65-85 years of age, evaluating the safety, tolerability, and immunogenicity of two dose levels (100 µg and 200 µg) of Pfizer’s C. difficile vaccine candidate on two different three-dose vaccination schedules (Days 1/8/30 and Months 0/1/6). More information about the PF-06425090 Phase 2 study can be found at www.clinicaltrials.gov (link is external).
About Clostridium difficile
Clostridium difficile (C. difficile) is a spore-forming pathogen that typically causes symptoms in individuals with altered gut microbial flora, releasing toxins that can result in a range of disease manifestations from asymptomatic colonization to diarrhea, pseudomembranous colitis, toxic megacolon, intestinal perforation, or, in the most severe cases, death.4,5 C. difficile, classified by the U.S. Centers for Disease Control and Prevention (CDC) as an urgent public health threat in 2013,6 is the most common cause of antibiotic-associated diarrhea in the healthcare setting and an increasing concern worldwide.7 Responsible for approximately 453,000 U.S. cases (associated with 29,000 deaths) in 2011,8 CDI disproportionately affects older adults, with nearly two-thirds of cases in patients over the age of 65.9 Current treatment options may offer temporary therapeutic improvements, but will not provide long-term protection.10 Up to 25% of patients treated for a first episode of CDI experience a first recurrence of infection, and up to 65% of those patients who experience a first recurrence will experience multiple recurrences.1,11
Pfizer Inc.: Working together for a healthier world
At Pfizer, we apply science and our global resources to bring therapies to people that extend and significantly improve their lives. We strive to set the standard for quality, safety and value in the discovery, development and manufacture of healthcare products. Our global portfolio includes medicines and vaccines as well as many of the world’s best-known consumer healthcare products. Every day, Pfizer colleagues work across developed and emerging markets to advance wellness, prevention, treatments and cures that challenge the most feared diseases of our time. Consistent with our responsibility as one of the world’s premier innovative biopharmaceutical companies, we collaborate with health care providers, governments and local communities to support and expand access to reliable, affordable health care around the world. For more than 150 years, Pfizer has worked to make a difference for all who rely on us. For more information, please visit us at www.pfizer.com. In addition, to learn more, follow us on Twitter at @Pfizer and @Pfizer_News, LinkedIn, YouTube, and like us on Facebook at Facebook.com/Pfizer.
DISCLOSURE NOTICE: The information contained in this release is as of January 26, 2017. Pfizer assumes no obligation to update forward-looking statements contained in this release as the result of new information or future events or developments. This release contains forward-looking information about a vaccine candidate, PF-06425090, including its potential benefits and the expected timing of commencement of a Phase 3 study, that involves substantial risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statements. Risks and uncertainties include, among other things, the uncertainties inherent in research and development, including the ability to meet anticipated clinical trial commencement and completion dates and regulatory submission dates, as well as the possibility of unfavorable clinical trial results, including unfavorable new clinical data and additional analyses of existing clinical data; risks associated with interim data; whether and when any biologics license applications may be filed for PF-06425090; whether and when any such applications may be approved by regulatory authorities, which will depend on the assessment by such regulatory authorities of the benefit-risk profile suggested by the totality of the efficacy and safety information submitted; decisions by regulatory authorities regarding labeling and other matters that could affect the availability or commercial potential of PF-06425090 and competitive developments. A further description of risks and uncertainties can be found in Pfizer’s Annual Report on Form 10-K for the fiscal year ended December 31, 2015 and in its subsequent reports on Form 10-Q, including in the sections thereof captioned “Risk Factors” and “Forward-Looking Information and Factors That May Affect Future Results,” as well as in its subsequent reports on Form 8-K, all of which are filed with the U.S. Securities and Exchange Commission and available at www.sec.gov (link is external) and www.pfizer.com.
1 Cohen SH et al. Infect Control Hosp Epidemiol. 2010;31:431-455.
2 Gerding DN and Young VB. Clostridium difficile infection. In: Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, 8th ed. Bennett JE, Dolin R, Blaser MJ (eds). Philadelphia, PA: Elsevier Saunders; 2015.
Synthetic Biologics’ SYN-004 (ribaxamase) Achieves Primary Endpoint in Phase 2b Trial for C. difficile Infection (CDI)
Synthetic Biologics, Inc. a late-stage clinical company developing therapeutics
that preserve the microbiome to protect and restore the health of patients, today
announced positive topline data from its Phase 2b clinical trial for SYN-004 (ribaxamase),
the Company’s first-in-class oral enzyme designed to protect the gut microbiome
from disruption caused by certain intravenous (IV) beta-lactam antibiotics.
The study, a randomized, double-blind, placebo controlled trial of 412 patients, met its primary endpoint of significantly reducing C. difficile Infection (CDI). Preliminary analysis of the data indicated seven confirmed cases of CDI in the placebo group compared to two cases in the ribaxamase treatment group. Patients receiving ribaxamase achieved a 71.4% relative risk reduction (p-value=0.045) in CDI rates compared to patients receiving placebo. Adverse events reported during this trial were comparable between treatment and placebo arms.
Synthetic Biologics is also in the process of analyzing data from several exploratory endpoints that were designed to evaluate ribaxamase’s ability to protect the gut microbiome from colonization by opportunistic bacteria such as C. difficile and other antibiotic-resistant pathogens. Preliminary analysis of the data demonstrated a significant reduction in new colonization by vancomycin-resistant enterococci (VRE) for patients receiving ribaxamase compared to placebo (p-value=0.0002). With agreement from the FDA, the study included a secondary endpoint to assess ribaxamase’s capacity to decrease the incidence of antibiotic-associated diarrhea from all causes. Preliminary analysis of the data suggested a trend towards such a reduction (p-value=0.13), which was due, for the most part, to the reduction of CDI.
These data are consistent with ribaxamase’s mechanism of action designed to protect and preserve the natural balance of the gut microbiome from the unintended effects of IV antibiotic use. The Company expects to share additional results from these exploratory endpoints as they become available later this year, including results focused on ribaxamase’s ability to prevent the emergence of antimicrobial resistance in the gut microbiome.
“These trial results provide a compelling demonstration of the potential of ribaxamase to help address the serious health impacts associated with CDI and infections from other opportunistic bacteria resulting from dysbiosis of the gut microbiome,” said Joseph Sliman, MD, SVP, Clinical and Regulatory Affairs. “More than 453,0001 patients are diagnosed with CDI annually in the U.S., resulting in approximately 29,0001 deaths as well as significant and sometimes prolonged illness. Ribaxamase has the potential to shorten hospital stays, diminish morbidity and mortality and reduce the emergence of antibiotic-resistant organisms in the gut microbiome by protecting patients from primary C. difficile infection resulting from IV antibiotic use.”
In addition to causing significant suffering and mortality, CDI adds an estimated economic burden of nearly $1.5 billion1 to the healthcare system each year, which could potentially be reduced with an effective therapeutic.
“The reduction in the relative risk of CDI represents a significant milestone in the clinical development of ribaxamase and we believe provides further validation for our approach to advancing cutting edge microbiome science,” said Jeffrey Riley, President and Chief Executive Officer. “These findings also help further our goals to bring the first ever microbiome-focused therapeutic to patients and to help illuminate the potential of this drug class to address serious diseases and public health concerns. We expect to share additional data from exploratory endpoints in the coming months and look forward to continuing ongoing and productive discussions with both the FDA and CDC on the protocol for Phase 3 pivotal trials for ribaxamase.”
Synthetic Biologics is also continuing to prepare for the initiation of pivotal Phase 2b/3 clinical trials for SYN-010, the Company’s proprietary, modified-release formulation of lovastatin lactone designed to treat the underlying cause of irritable bowel syndrome with constipation (IBS-C).
Presentation Planned for Biotech Showcase 2017 Conference
Date: Monday, January 9, 2017 Time: 9:30 a.m. (PT) / 12:30 p.m. (ET) Location: Hilton San Francisco Union Square, San Francisco, CA
SYN-004 (ribaxamase) is a first-in-class oral enzyme designed to degrade certain IV beta-lactam antibiotics within the GI tract and maintain the natural balance of the gut microbiome for the prevention of CDI, AAD and the emergence of antibiotic-resistant organisms. The Phase 2b proof-of-concept clinical trial is intended to evaluate the effectiveness of ribaxamase to prevent the onset of primary C. difficile infection (CDI), antibiotic-associated diarrhea (AAD) and the emergence of antibiotic-resistant organisms in patients hospitalized with a lower respiratory infection and receiving IV ceftriaxone. A total of 412 subjects were randomized in a 1:1 ratio receiving either 150 mg dose strength of SYN-004 (ribaxamase) or placebo orally QID from Day 1 and until 72 hours following their last treatment of IV ceftriaxone. The sample size was determined to provide 80% power to detect the treatment effect with a one-sided alpha of 0.05. P-values were determined based on a 1-sided z-test for the comparison of the treatment difference as pre-specified in the statistical analysis plan. To access the ribaxamase mechanism of action video on Synthetic Biologics’ website, please click here.
About Synthetic Biologics, Inc.
Synthetic Biologics, Inc. (NYSE MKT: SYN) is a late-stage clinical company developing therapeutics that preserve the microbiome to protect and restore the health of patients. The Company’s lead candidates poised for Phase 3 development are: (1) SYN-010 which is intended to reduce the impact of methane producing organisms in the gut microbiome to treat an underlying cause of irritable bowel syndrome with constipation (IBS-C), and (2) SYN-004 (ribaxamase) which is designed to protect the gut microbiome from the effects of certain commonly used intravenous (IV) beta-lactam antibiotics for the prevention of C. difficile infection, antibiotic-associated diarrhea (AAD) and the emergence of antibiotic-resistant organisms. The Company is also developing preclinical stage monoclonal antibody therapies for the prevention and treatment of pertussis and novel discovery stage biotherapeutics for the treatment of phenylketonuria (PKU). For more information, please visit Synthetic Biologics’ website at www.syntheticbiologics.com.
This release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. In some cases, forward-looking statements can be identified by terminology such as “may,” “should,” “potential,” “continue,” “expects,” “anticipates,” “intends,” “plans,” “believes,” “estimates” and similar expressions and include statements regarding the potential ofribaxamase to help address the serious health impacts associated with CDI and infections from other opportunistic bacteria resulting from dysbiosis of the gut microbiome, the industry data regarding the expected incidence and economic burden of CDI, the potential of ribaxamase to shorten hospital stays, diminish morbidity and mortality and reduce the emergence of antibiotic resistant organisms in the gut microbiome by protecting patients from primary C. difficile infection resulting from IV antibiotic use, the potential to reduce the economic burden to the healthcare system from an effective therapeutic, the suggested trend toward a reduction of incidence of antibiotic-associated diarrhea from all causes, the expected timing of data release of exploratory endpoints of the trial focused on the ability of ribaxamase to prevent the emergence of antibiotic-resistant organisms in the gut microbiome, the continued ongoing discussions with the FDA and CDC, validation for our approach to advancing cutting edge microbiome science, the continued preparation for the initiation of pivotal Phase 2b/3 clinical trials for SYN-010, the potential of the drug class to address serious diseases and public health concerns, the ability of SYN-004 to protect the gut microbiome from the effects of certain commonly used IV beta-lactam antibiotics for the prevention of C. difficile infection, antibiotic-associated diarrhea (AAD) and the emergence of antibiotic-resistant organisms. These forward-looking statements are based on management’s expectations and assumptions as of the date of this press release and are subject to a number of risks and uncertainties that could cause actual results to differ materially from those set forth or implied by any forward-looking statements.Important factors that could cause actual results to differ materially from current expectations include, among others, Synthetic Biologics’ product candidates demonstrating safety and effectiveness, as well as results that are consistent with prior results, Synthetic Biologics’ ability to initiate clinical trials and if initiated, to complete them on time and achieve desired results and benefits, Synthetic Biologics’ clinical trials continuing enrollment as expected, Synthetic Biologics’ ability to obtain regulatory approvals for commercialization of product candidates or to comply with ongoing regulatory requirements, regulatory limitations relating to Synthetic Biologics’ ability to promote or commercialize its product candidates for specific indications, acceptance of its product candidates in the marketplace and the successful development, marketing or sale of Synthetic Biologics’ products by competitors that render Synthetic Biologics’ products obsolete or non-competitive, Synthetic Biologics’ ability to maintain its license agreements, the continued maintenance and growth of Synthetic Biologics’patent estate, Synthetic Biologics becoming and remaining profitable, Synthetic Biologics’ability to establish and maintain collaborations, Synthetic Biologics’ability to obtain or maintain the capital or grants necessary to fund its research and development activities, a loss of any of Synthetic Biologics’key scientists or management personnel,and other factors described in Synthetic Biologics’ Annual Report on Form 10-K for the year ended December 31, 2015 and its other filings with the SEC, including subsequent periodic reports on Forms 10-Q and 8-K.The information in this release is provided only as of the date of this release, and Synthetic Biologics undertakes no obligation to update any forward-looking statements contained in this release on account of new information, future events, or otherwise, except as required by law.
1: Leffler DA et al. N Engl J Med 2015; 372: 1539-1548