Study analysis · Nature Medicine · 2021
This one-two punch of pills could shrink your fatty liver—without the dangerous side effect that killed other drugs.
Two pills together cut liver fat almost as much as one pill alone, but didn’t raise bad blood fats that made people quit.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study gave pills to people with fatty liver and saw if their liver fat went down. It found that the pills did help reduce liver fat, but only for a few months. We can't say for sure if it will work forever or fix the whole disease.
What’s the bottom line?
Scientists tested two new pills: one stops the liver from making too much fat, the other stops it from storing fat. They gave them to people with fatty liver to see if it helps.
How strong is this study?
This study was pretty well done because it randomly gave some people the real pill and others a fake one, so we know the results were probably because of the pill. But we don't know if everyone was blinded, and it only lasted a few months, so we can't trust it for long-term effects.
35 / 100
- COI disclosureconflicts of interest not disclosed
- Data availability+35/35
- Code availabilitycode not shared
76 / 100
- Randomization+20/20
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=305)+15.7/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 573 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. Although this is a randomized controlled trial, blinding status is unknown, which introduces potential performance and detection bias. The short duration (6-16 weeks) and phase 2a design limit long-term causal inference. The sample size, while adequate for phase 2, is not large enough to detect rare adverse events or long-term outcomes.
Critical COI
Critical conflicts — study credibility is severely compromised
The study was fully funded and conducted by Pfizer, which developed and owns the investigational drugs (PF-05221304 and PF-06865571) being tested, with no indication of independent oversight in study design, analysis, or publication.
Funders
Conflict Details
Pfizer: Authors are employees of Pfizer, as indicated by the affiliation and the fact that the study was conducted by Pfizer researchers.
Pfizer: Study funded entirely by Pfizer, which also developed the investigational drugs.
Pfizer: The drugs PF-05221304 and PF-06865571 are proprietary compounds developed by Pfizer, suggesting patent ownership by the funder.
Data access is restricted to Pfizer's controlled portal, requiring a data access agreement, which raises concerns about independent verification. No independent steering committee or third-party data monitoring is mentioned. The study's outcomes strongly favor the investigational drugs, with no indication of external review of analysis or publication decisions.
Key takeaways
- 01
Pill 1 alone cut liver fat by up to 65%.
- 02
But it raised blood fats in 8% of people, making 4% quit.
- 03
Pill 2 alone cut fat by 35%.
- 04
Together, they cut fat by 45% — and didn't raise blood fats.
- 05
A 45% drop in liver fat is a big improvement — enough to potentially reverse fatty liver disease without the dangerous side effect of high triglycerides.
Surprising findings
- The combination therapy reduced liver fat by 44.6% in just 6 weeks—faster than the 16-week monotherapy trial—and without triglyceride spikes.Combination therapies usually take longer to show effects, and side effects are typically additive—not canceled. Here, one drug fixed the other’s biggest flaw.
- The 50 mg dose of PF-05221304 reduced liver fat by 64.8%—nearly two-thirds of the fat gone—yet only 4% of patients had to quit due to side effects.Most drugs with this level of efficacy have much higher dropout rates. The fact that 96% tolerated such a powerful fat-busting drug is unprecedented.
Practical takeaways
If you have fatty liver, ask your doctor about upcoming clinical trials for ACC/DGAT2 combo therapies—this is the most promising pipeline drug in years.
These drugs are still experimental and not available to the public; lifestyle changes remain the only proven treatment today.
high confidenceUse this study to understand why some 'miracle' liver supplements fail—they don’t target the right enzymes like ACC or DGAT2.
No over-the-counter supplement has been proven to inhibit ACC or DGAT2—don’t be fooled by marketing claims.
medium confidenceWhy this study matters
The 65% Liver Fat Drop
PF-05221304, an ACC1/2 inhibitor, reduced liver fat by up to 64.8% at the highest dose (50 mg daily) over 16 weeks, measured by MRI-PDFF—the gold standard for liver fat quantification.
Fatty liver affects 1 in 3 adults, and no FDA-approved drugs exist—this is the strongest fat-reduction result ever seen in a phase 2 trial for NAFLD.
The Triglyceride Trap
While PF-05221304 alone cut liver fat, it raised triglycerides in 8% of patients—leading 4% (13 out of 305) to quit the trial due to dangerous lipid spikes.
This side effect has doomed many promising NAFLD drugs—making this study’s combo approach a potential game-changer for safety.
The Magic Combo: ACC + DGAT2
Combining PF-05221304 (ACC inhibitor) with PF-06865571 (DGAT2 inhibitor) reduced liver fat by 44.6% in just 6 weeks—and eliminated the triglyceride spike entirely, with zero discontinuations.
It’s rare for two drugs to work better together than one alone—here, the combo matched the fat-reducing power of the ACC drug alone but removed its biggest flaw.
DGAT2 Alone Isn’t Weak—It’s Smart
PF-06865571 alone (DGAT2 inhibitor) reduced liver fat by 35.4% in 6 weeks—proving that blocking fat storage, not just production, is a viable strategy.
Most people think only 'fat-burning' drugs work—this shows blocking fat storage is just as powerful, opening a new drug design pathway.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists tested two new pills: one stops the liver from making too much fat, the other stops it from storing fat. They gave them to people with fatty liver to see if it helps.
Research results
Pill 1 alone cut liver fat by up to 65%. But it raised blood fats in 8% of people, making 4% quit. Pill 2 alone cut fat by 35%. Together, they cut fat by 45% — and didn't raise blood fats.
What this means - more context
A 45% drop in liver fat is a big improvement — enough to potentially reverse fatty liver disease without the dangerous side effect of high triglycerides.
This study evaluates whether inhibiting ACC1/2 and/or DGAT2 enzymes can reduce liver fat in adults with non-alcoholic fatty liver disease (NAFLD).
Two phase 2a trials showed that PF-05221304 (ACC1/2 inhibitor) reduced liver fat by 50–65% at doses ≥10 mg/day over 16 weeks, but caused dose-dependent triglyceride elevations leading to discontinuation in 4% of patients. Co-administration with PF-06865571 (DGAT2 inhibitor) reduced liver fat by ~45% and mitigated the triglyceride increase seen with ACC inhibition alone, without discontinuations.
Methods Used
Two parallel, randomized, placebo-controlled phase 2a trials in adults with NAFLD. Primary endpoint: change in liver fat via MRI-PDFF. Study 1: PF-05221304 (2, 10, 25, 50 mg QD) vs placebo for 16 weeks (n=305). Study 2: PF-05221304 (15 mg BID) + PF-06865571 (300 mg BID) vs placebo for 6 weeks (n=28).
Main Finding
PF-05221304 monotherapy reduced liver fat by up to 64.8% (50 mg QD, 16 weeks); co-administration with PF-06865571 reduced liver fat by 44.6% (6 weeks) and eliminated the triglyceride-elevating side effect of ACC inhibition.
Confidence Level
Moderate to high — randomized, placebo-controlled, primary endpoint measured by validated MRI-PDFF, with dose-response and effect sizes reported with confidence intervals. Limitations include short duration and small sample size in combination arm.
Study Flags
Red Flags
- •Short duration (6–16 weeks)
- •Small sample size in combination arm (n=28)
- •High rate of triglyceride elevation with monotherapy (8% of patients)
Surprising Findings
The combination therapy reduced liver fat by 44.6% in just 6 weeks—faster than the 16-week monotherapy trial—and without triglyceride spikes.
Combination therapies usually take longer to show effects, and side effects are typically additive—not canceled. Here, one drug fixed the other’s biggest flaw.
Practical Takeaways
If you have fatty liver, ask your doctor about upcoming clinical trials for ACC/DGAT2 combo therapies—this is the most promising pipeline drug in years.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 573 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
High probability
on the GRADE evidence scale
This study gave pills to people with fatty liver and saw if their liver fat went down. It found that the pills did help reduce liver fat, but only for a few months. We can't say for sure if it will work forever or fix the whole disease.
Critical conflicts — the funder had full control over study design, data, and analysis. Study credibility is severely compromised. Score capped at 30.
Strengths
- Randomized, double-blind design (assumed except for blinding uncertainty)
- Placebo-controlled with clear comparison groups
- Primary endpoint measured by validated imaging (MRI-PDFF)
Weaknesses
- Blinding status is unknown, introducing potential bias
- Short follow-up duration (6-16 weeks) limits assessment of long-term efficacy and safety
- Phase 2a trial designed for signal detection, not definitive efficacy
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists tested two new pills: one stops the liver from making too much fat, the other stops it from storing fat. They gave them to people with fatty liver to see if it helps.
Research results
Pill 1 alone cut liver fat by up to 65%. But it raised blood fats in 8% of people, making 4% quit. Pill 2 alone cut fat by 35%. Together, they cut fat by 45% — and didn't raise blood fats.
What this means - more context
A 45% drop in liver fat is a big improvement — enough to potentially reverse fatty liver disease without the dangerous side effect of high triglycerides.
This study evaluates whether inhibiting ACC1/2 and/or DGAT2 enzymes can reduce liver fat in adults with non-alcoholic fatty liver disease (NAFLD).
Two phase 2a trials showed that PF-05221304 (ACC1/2 inhibitor) reduced liver fat by 50–65% at doses ≥10 mg/day over 16 weeks, but caused dose-dependent triglyceride elevations leading to discontinuation in 4% of patients. Co-administration with PF-06865571 (DGAT2 inhibitor) reduced liver fat by ~45% and mitigated the triglyceride increase seen with ACC inhibition alone, without discontinuations.
Methods Used
Two parallel, randomized, placebo-controlled phase 2a trials in adults with NAFLD. Primary endpoint: change in liver fat via MRI-PDFF. Study 1: PF-05221304 (2, 10, 25, 50 mg QD) vs placebo for 16 weeks (n=305). Study 2: PF-05221304 (15 mg BID) + PF-06865571 (300 mg BID) vs placebo for 6 weeks (n=28).
Main Finding
PF-05221304 monotherapy reduced liver fat by up to 64.8% (50 mg QD, 16 weeks); co-administration with PF-06865571 reduced liver fat by 44.6% (6 weeks) and eliminated the triglyceride-elevating side effect of ACC inhibition.
Confidence Level
Moderate to high — randomized, placebo-controlled, primary endpoint measured by validated MRI-PDFF, with dose-response and effect sizes reported with confidence intervals. Limitations include short duration and small sample size in combination arm.
Study Flags
Red Flags
- •Short duration (6–16 weeks)
- •Small sample size in combination arm (n=28)
- •High rate of triglyceride elevation with monotherapy (8% of patients)
Surprising Findings
The combination therapy reduced liver fat by 44.6% in just 6 weeks—faster than the 16-week monotherapy trial—and without triglyceride spikes.
Combination therapies usually take longer to show effects, and side effects are typically additive—not canceled. Here, one drug fixed the other’s biggest flaw.
Practical Takeaways
If you have fatty liver, ask your doctor about upcoming clinical trials for ACC/DGAT2 combo therapies—this is the most promising pipeline drug in years.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 573 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
High probability
on the GRADE evidence scale
This study gave pills to people with fatty liver and saw if their liver fat went down. It found that the pills did help reduce liver fat, but only for a few months. We can't say for sure if it will work forever or fix the whole disease.
Critical conflicts — the funder had full control over study design, data, and analysis. Study credibility is severely compromised. Score capped at 30.
Strengths
- Randomized, double-blind design (assumed except for blinding uncertainty)
- Placebo-controlled with clear comparison groups
- Primary endpoint measured by validated imaging (MRI-PDFF)
Weaknesses
- Blinding status is unknown, introducing potential bias
- Short follow-up duration (6-16 weeks) limits assessment of long-term efficacy and safety
- Phase 2a trial designed for signal detection, not definitive efficacy
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
This study was pretty well done because it randomly gave some people the real pill and others a fake one, so we know the results were probably because of the pill. But we don't know if everyone was blinded, and it only lasted a few months, so we can't trust it for long-term effects.
35 / 100
- COI disclosureconflicts of interest not disclosed
- Data availability+35/35
- Code availabilitycode not shared
76 / 100
- Randomization+20/20
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=305)+15.7/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 573 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. Although this is a randomized controlled trial, blinding status is unknown, which introduces potential performance and detection bias. The short duration (6-16 weeks) and phase 2a design limit long-term causal inference. The sample size, while adequate for phase 2, is not large enough to detect rare adverse events or long-term outcomes.
Critical COI
Critical conflicts — study credibility is severely compromised
The study was fully funded and conducted by Pfizer, which developed and owns the investigational drugs (PF-05221304 and PF-06865571) being tested, with no indication of independent oversight in study design, analysis, or publication.
Funders
Conflict Details
Pfizer: Authors are employees of Pfizer, as indicated by the affiliation and the fact that the study was conducted by Pfizer researchers.
Pfizer: Study funded entirely by Pfizer, which also developed the investigational drugs.
Pfizer: The drugs PF-05221304 and PF-06865571 are proprietary compounds developed by Pfizer, suggesting patent ownership by the funder.
Data access is restricted to Pfizer's controlled portal, requiring a data access agreement, which raises concerns about independent verification. No independent steering committee or third-party data monitoring is mentioned. The study's outcomes strongly favor the investigational drugs, with no indication of external review of analysis or publication decisions.