Tumor lysate particle only vaccine (TLPO) vs. Tumor lysate particle-loaded, dendritic cell vaccine (TLPLDC) to prevent recurrence in resected stage III/IV melanoma patients: Results of a phase I/IIa trial.

BACKGROUND: The autologous tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine is produced from dendritic cells (DC) loaded ex vivo with autologous tumor lysate (TL). TLPLDC has been shown to decrease recurrence in resected Stage III/IV melanoma patients in a Phase IIb trial. The TL particle only (TLPO) vaccine is produced by loading of yeast cell wall particles with autologous TL and direct injection allowing for in vivo DC loading. We have compared the TLPO and TLPLDC vaccines in an embedded Phase I/IIa trial of a larger Phase IIb trial of the TLPLDC vaccine. METHODS: Patients rendered clinically disease-free after surgery were randomized 2:1 to receive the TLPO or TLPLDC vaccine and followed for recurrence and death. Patients had scheduled intradermal inoculations at 0, 1, 2, 6, 12, and 18 months after enrollment. Kaplan-Meier and log-rank analysis were used to compare disease-free survival (DFS) and overall survival (OS) in an intention-to-treat (ITT) analysis. RESULTS: Sixty-three patients were randomized, 43 TLPO and 20 TLPLDC. Patients randomized to the TLPO arm were more likely to be female (37.2% vs. 10.0 %, p = 0.026), but otherwise no significant clinicopathological differences were identified. No differences in related adverse events (AE) were found between treatment arms. At a median follow-up of 20.5 months, the DFS (60.8% vs. 58.7 %, p = 0.714) and OS (94.6% vs. 93.8 %, p = 0.966) were equivalent between the TLPO and TLPLDC groups, respectively. No statistical differences were found in subgroup analyses between vaccine types, which accounted for receipt of immunotherapy and the use of G-CSF pre-blood draw. CONCLUSIONS: In a randomized, double-blind Phase I/IIa trial, there were no differences in DFS or OS in resected Stage III/IV melanoma patients receiving adjuvant TLPO versus TLPLDC vaccines. Given manufacturing advantages, further efficacy testing of TLPO is warranted in a Phase III trial.

Evaluation of TrpM and PsiD substrate promiscuity reveals new biocatalytic capabilities.

N-methylated tryptamines, such as the hallucinogenic natural products, psilocybin and N,N-dimethyltryptamine (DMT), are gaining interest from the medical community due to their potential as next generation treatments for mental health disorders. The clinical relevance of these compounds has driven scientists to develop biosynthetic production routes to a number of tryptamine drug candidates, and efforts are ongoing to expand and further develop these biosynthetic capabilities. To that end, we have further characterized the substrate preferences of two enzymes involved in tryptamine biosynthesis: TrpM, a tryptophan N-methyltransferase from Psilocybe serbica, and PsiD, the gateway decarboxylase of the psilocybin biosynthesis pathway. Here, we show that TrpM can N-methylate the non-native amino acid substrate, 4-hydroxytryptophan, a key intermediate in the Escherichia coli-based recombinant psilocybin biosynthesis pathway. However, the ability to incorporate TrpM into a functional psilocybin biosynthesis pathway was thwarted by PsiD's inability to use N,N-dimethyl-4-hydroxytryptophan as substrate, under the culturing conditions tested, despite demonstrating activity on N-methylated and 4-hydroxylated tryptophan derivatives individually. Taken together, this work expands upon the known substrates for TrpM and PsiD, further increasing the diversity of tryptamine biosynthetic products.

The benefit of adjuvant chemotherapy following pancreaticoduodenectomy for pancreatic adenocarcinoma depends on response to neoadjuvant therapy.

BACKGROUND: The benefit of adjuvant therapy (AT) remains unclear in pancreatic ductal adenocarcinoma (PDAC) after neoadjuvant therapy (NAT) and surgical resection. METHODS: The 2019 National Cancer Database was queried for patients with non-metastatic PDAC who received NAT followed by pancreaticoduodenectomy. Only patients with data regarding receipt of AT were included. Patients were classified if they had nodal down-staging specifically, or any downstaging (Tumor, Nodal, or overall). Propensity score matching (PSM) adjusted for pretreatment covariate imbalance between groups. The weighted Kaplan-Meier method and log-rank test were used to estimate the cumulative survival. RESULTS: After exclusion criteria and PSM, a total of 2784 patients remained; 1689 (60.7%) received AT and 1095 (39.3%) did not receive AT. Among all, those with additional AT had a significantly improved overall survival (OS) (p < 0.001). Upon evaluation of patients without downstaging after NAT, those who received AT had improved OS (no nodal downstaging or any downstaging; p = 0.002; p = 0.001). When evaluating patients with downstaging after NAT, those receiving AT did not have improved OS (nodal downstaging or any downstaging: p = 0.352; p = 0.99). CONCLUSION: Response to NAT appears to correlate with the benefit of AT following pancreaticoduodenectomy; patients who have a favorable response to NAT may not benefit from AT.

Implementation of a novel peer review academy by Surgery and the Association of Women Surgeons.

BACKGROUND: A novel Peer Review Academy was developed as a collaborative effort between the Association of Women Surgeons and the journal Surgery to provide formal training in peer review. We aimed to describe the outcomes of this initiative using a mixed methods approach. METHODS: We developed a year-long curriculum with monthly online didactic sessions. Women surgical trainee mentees were paired 1:1 with rotating women surgical faculty mentors for 3 formal peer review opportunities. We analyzed pre-course and post-course surveys to evaluate mentee perceptions of the academy and assessed changes in mentee review quality over time with blinded scoring of unedited reviews. Semi-structured interviews were conducted upon course completion. RESULTS: Ten women surgical faculty mentors and 10 women surgical trainees from across the United States and Canada successfully completed the Peer Review Academy. There were improvements in the mentees' confidence for all domains of peer review evaluated, including overall confidence in peer review, study novelty, study design, analytic approach, and review formatting (all, P ≤ .02). The mean score of peer review quality increased over time (59.2 ± 10.8 vs 76.5 ± 9.4; P = .02). In semi-structured interviews, important elements were emphasized across the Innovation, Implementation Process, and Individuals Domains, including the values of (1) a comprehensive approach to formal peer review education; (2) mentoring relationships between women faculty and resident surgeons; and (3) increasing diversity in the scientific peer review process. CONCLUSION: Our novel Peer Review Academy was feasible on a national scale, resulting in significant qualitative and quantitative improvements in women surgical trainee skillsets, and has the potential to grow and diversify the existing peer review pool.

Tube Thoracostomy Complications in Patients With ARDS Requiring ECMO: Worse in COVID-19 Patients?

INTRODUCTION: The incidence and management outcomes of COVID-19 patients with acute respiratory distress syndrome (ARDS) on veno-venous extracorporeal membrane oxygenation (V-V ECMO) requiring chest tubes are not well-described. This study sought to explore differences in tube thoracostomy rates and subsequent complications between patients with and without COVID-19 ARDS on V-V ECMO. MATERIALS AND METHODS: This study is a single institution, retrospective cohort study of patients with COVID-19 ARDS requiring V-V ECMO. The control cohort consisted of patients who required V-V ECMO for ARDS-related diagnoses from January 2018 to January 2021. The primary outcome was any complication following initial tube thoracostomy placement. Study approval was obtained from the Brooke Army Medical Center Institutional Review Board (C.2017.152d). RESULTS: Twenty-five COVID-19 patients and 38 controls were included. Demographic parameters did not differ between the groups. The incidence of pneumothorax was not significantly different between the two groups (44% COVID-19 vs. 22% control, OR 2.8, 95% CI 0.95-7.9, P = 0.09). Patients with COVID-19 were as likely to receive tube thoracostomy as controls (36% vs. 24%, OR 1.8, 95% CI 0.55-5.7). Complications, however, were more likely to occur in the COVID-19 group (89% vs. 33%, OR 16, 95% CI, 1.6-201, P = 0.0498). CONCLUSIONS: Tube thoracostomy placement in COVID-19 patients with ARDS requiring V-V ECMO is common, as are complications following initial placement. Clinicians should anticipate the need for re-intervention in this patient population. Small-bore (14Fr and smaller) pigtail catheters appeared to be safe and efficacious in this setting, but further study on tube thoracostomy management in ECMO patients is needed.

Prospective, randomized, double-blind phase 2B trial of the TLPO and TLPLDC vaccines to prevent recurrence of resected stage III/IV melanoma: a prespecified 36-month analysis.

BACKGROUND: The tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine is made by ex vivo priming matured autologous dendritic cells (DCs) with yeast cell wall particles (YCWPs) loaded with autologous tumor lysate (TL). The tumor lysate, particle only (TLPO) vaccine uses autologous TL-loaded YCWPs coated with silicate for in vivo DC loading. Here we report the 36-month prespecified analyses of this prospective, randomized, double-blind trial investigating the ability of the TLPO and TLPLDC (±granulocyte-colony stimulating factor (G-CSF)) vaccines to prevent melanoma recurrence in high-risk patients. METHODS: Patients with clinically disease-free stage III/IV melanoma were randomized 2:1 initially to TLPLDC versus placebo (n=124) and subsequently TLPO versus TLPLDC (n=63). All patients were randomized and blinded; however, the placebo control arm was replaced in the second randomization scheme with another novel vaccine; some analyses in this paper therefore reflect a combination of the two randomization schemes. Patients receiving the TLPLDC vaccine were further divided by their method of DC harvest (with or without G-CSF pretreatment); this was not randomized. The use of standard of care checkpoint inhibitors was not stratified between groups. Safety was assessed and Kaplan-Meier and log-rank analyses compared disease-free (DFS) and overall survival (OS). RESULTS: After combining the two randomization processes, a total of 187 patients were allocated between treatment arms: placebo (n=41), TLPLDC (n=103), or TLPO (n=43). The allocation among arms created by the addition of patients from the two separate randomization schemes does not reflect concurrent randomization among all treatment arms. TLPLDC was further divided by use of G-CSF in DC harvest: no G-CSF (TLPLDC) (n=47) and with G-CSF (TLPLDC+G) (n=56). Median follow-up was 35.8 months. Only two patients experienced a related adverse event ≥grade 3, one each in the TLPLDC+G and placebo arms. DFS was 27.2% (placebo), 55.4% (TLPLDC), 22.9% (TLPLDC+G), and 60.9% (TLPO) (p<0.001). OS was 62.5% (placebo), 93.6% (TLPLDC), 57.7% (TLPLDC+G), and 94.6% (TLPO) (p=0.002). CONCLUSIONS: The TLPO and TLPLDC (without G-CSF) vaccines were associated with improved DFS and OS in this clinical trial. Given production and manufacturing advantages, the efficacy of the TLPO vaccine will be confirmed in a phase 3 trial. TRIAL REGISTRATION NUMBER: NCT02301611.

Impact of Adherence to Operative Standards and Stage-Specific Guideline-Recommended Therapy in Nonmetastatic Pancreatic Adenocarcinoma.

BACKGROUND: Achieving optimal surgical outcomes in pancreatic adenocarcinoma requires a combination of both curative-intent resection to oncologic standards and stage-specific neoadjuvant or adjuvant therapy. This investigation sought to examine factors associated with receipt of standard-adherent surgery (SAS) and guideline-recommended therapy (GRT) and determine the impact of compliance on patient survival. PATIENTS AND METHODS: From the 2006-2016 National Cancer Database, 21,304 patients underwent resection for nonmetastatic pancreatic adenocarcinoma. SAS was defined as pancreatic resection with negative margins and ≥ 15 lymph nodes examined. Stage-specific GRT was defined by current National Comprehensive Cancer Network guidelines. Multivariable models were used to determine predictors of adherence to SAS and GRT and prognostic impact on overall survival. RESULTS: Overall, SAS was achieved in 39% and GRT in 65% of patients, but only 30% received both SAS and GRT. Increasing age, minority race, uninsured status, and greater comorbidities were associated with a decreased odds of receiving both SAS and GRT (all p < 0.05). SAS (HR 0.79; CI 0.76-0.81; p < 0.001) and GRT (HR 0.67; CI 0.65-0.69; p < 0.001) were each independently associated with a survival advantage. Receipt of both SAS and GRT was associated with significant improvement in median OS compared with receiving neither (2.2 years vs 1.1 years; p < 0.001) which was independently associated with a 78% increased risk of death (HR 1.78; CI 1.70-1.86; p < 0.001). CONCLUSIONS: Despite survival benefits associated with adherence to operative standards and receipt of guideline-recommended therapy, compliance remains poor. Future efforts must be directed toward improved education and implementation efforts around both operative standards and therapy guidelines.

"Biosynthesis of psilocybin and its nonnatural derivatives by a promiscuous psilocybin synthesis pathway in Escherichia coli".

Traditional psychedelics are undergoing a transformation from recreational drugs, to promising pharmaceutical drug candidates with the potential to provide an alternative treatment option for individuals struggling with mental illness. Sustainable and economic production methods are thus needed to facilitate enhanced study of these drug candidates to support future clinical efforts. Here, we expand upon current bacterial psilocybin biosynthesis by incorporating the cytochrome P450 monooxygenase, PsiH, to enable the de novo production of psilocybin as well as the biosynthesis of 13 psilocybin derivatives. The substrate promiscuity of the psilocybin biosynthesis pathway was comprehensively probed by using a library of 49 single-substituted indole derivatives, providing biophysical insights to this understudied metabolic pathway and opening the door to the in vivo biological synthesis of a library of previously unstudied pharmaceutical drug candidates.

Tumor infiltrating lymphocytes as an endpoint in cancer vaccine trials.

Checkpoint inhibitors have invigorated cancer immunotherapy research, including cancer vaccination. Classic early phase trial design and endpoints used in developing chemotherapy are not suited for evaluating all forms of cancer treatment. Peripheral T cell response dynamics have demonstrated inconsistency in assessing the efficacy of cancer vaccination. Tumor infiltrating lymphocytes (TILs), reflect the local tumor microenvironment and may prove a superior endpoint in cancer vaccination trials. Cancer vaccines may also promote success in combination immunotherapy treatment of weakly immunogenic tumors. This review explores the impact of TILs as an endpoint for cancer vaccination in multiple malignancies, summarizes the current literature regarding TILs analysis, and discusses the challenges of providing validity and a standardized implementation of this approach.

SAGES/AHPBA guidelines for the use of minimally invasive surgery for the surgical treatment of colorectal liver metastases (CRLM).

BACKGROUND: Colorectal liver metastases (CRLM) occur in roughly half of patients with colorectal cancer. Minimally invasive surgery (MIS) has become an increasingly acceptable and utilized technique for resection in these patients, but there is a lack of specific guidelines on the use of MIS hepatectomy in this setting. A multidisciplinary expert panel was convened to develop evidence-based recommendations regarding the decision between MIS and open techniques for the resection of CRLM. METHODS: Systematic review was conducted for two key questions (KQ) regarding the use of MIS versus open surgery for the resection of isolated liver metastases from colon and rectal cancer. Evidence-based recommendations were formulated using the GRADE methodology by subject experts. Additionally, the panel developed recommendations for future research. RESULTS: The panel addressed two KQs, which pertained to staged or simultaneous resection of resectable colon or rectal metastases. The panel made conditional recommendations for the use of MIS hepatectomy for both staged and simultaneous resection when deemed safe, feasible, and oncologically effective by the surgeon based on the individual patient characteristics. These recommendations were based on low and very low certainty of evidence. CONCLUSIONS: These evidence-based recommendations should provide guidance regarding surgical decision-making in the treatment of CRLM and highlight the importance of individual considerations of each case. Pursuing the identified research needs may help further refine the evidence and improve future versions of guidelines for the use of MIS techniques in the treatment of CRLM.

Impact of Mediating and Confounding Variables on the Volume-Outcome Association in the Treatment of Pancreatic Cancer.

BACKGROUND: High-volume centers (HVC), academic centers (AC), and longer travel distances (TD) have been associated with improved outcomes for patients undergoing surgery for pancreatic adenocarcinoma (PAC). Effects of mediating variables on these associations remain undefined. The purpose of this study is to examine the direct effects of hospital volume, facility type, and travel distance on overall survival (OS) in patients undergoing surgery for PAC and characterize the indirect effects of patient-, disease-, and treatment-related mediating variables. PATIENTS AND METHODS: Using the National Cancer Database, patients with non-metastatic PAC who underwent resection were stratified by annual hospital volume (< 11, 11-19, and ≥ 20 cases/year), facility type (AC versus non-AC), and TD (≥ 40 versus < 40 miles). Associations with survival were evaluated using multiple regression models. Effects of mediating variables were assessed using mediation analysis. RESULTS: In total, 19,636 patients were included. Treatment at HVC or AC was associated with lower risk of death [hazard ratio (HR) 0.90, confidence interval (CI) 0.88-0.92; HR 0.89, CI 0.86-0.91, respectively]. TD did not impact OS. Patient-, disease-, and treatment-related variables explained 25.5% and 41.8% of the survival benefit attained from treatment at HVC and AC, reducing the survival benefit directly attributable to each variable to 4.9% and 6.4%, respectively. CONCLUSIONS: Treatment of PAC at HVC and AC was associated with improved OS, but the magnitude of this benefit was less when mediating variables were considered. From a healthcare utilization and cost-resource perspective, further research is needed to identify patients who would benefit most from selective referral to HVC or AC.

Morbidity and Mortality of Non-pancreatectomy operations for pancreatic cancer: An ACS-NSQIP analysis.

BACKGROUND: Patients with pancreas cancer may undergo palliative gastrointestinal or biliary bypass. Recent comparisons of post-operative outcomes following such procedures are lacking. METHODS: We analyzed patients undergoing exploration, gastrojejunostomy, biliary bypass or double bypass for pancreatic cancer using data from the 2005-2019 American College of Surgeons National Surgical Quality Improvement Program. We compared 30-day mortality and complications across procedures and over time periods (2005-10, 2011-14, 2015-19) using multivariable regression models. Factors associated with postoperative mortality were identified. RESULTS: Of 43,525 patients undergoing surgery with a postoperative diagnosis of pancreatic cancer, 5572 met inclusion criteria. Palliative operations included 1037 gastrojejunostomies, 792 biliary bypasses, 650 double bypasses, and 3093 explorations. The proportion of biliary and double bypass procedures decreased from 2005-10 to 2015-19. Gastrojejunostomy had higher 30-day mortality rate (11.5%) than other operations (p < 0.001). Adjusted 30-day mortality rates remained stable over time (7.8% vs 6.3%, p = 0.095), while rates of serious complications decreased over time (23.2% vs 17.1%, p < 0.001). CONCLUSIONS: Palliative bypass for pancreatic cancer has not become safer over time, and 30-day mortality and complications remain high.

Divergent clinical outcomes in a phase 2B trial of the TLPLDC vaccine in preventing melanoma recurrence and the impact of dendritic cell collection methodology: a randomized clinical trial.

BACKGROUND: A randomized, double-blind, placebo-controlled phase 2b trial of the tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine was conducted in patients with resected stage III/IV melanoma. Dendritic cells (DCs) were harvested with and without granulocyte-colony stimulating factor (G-CSF). This analysis investigates differences in clinical outcomes and RNA gene expression between DC harvest methods. METHODS: The TLPLDC vaccine is created by loading autologous tumor lysate into yeast cell wall particles (YCWPs) and exposing them to phagocytosis by DCs. For DC harvest, patients had a direct blood draw or were pretreated with G-CSF before blood draw. Patients were randomized 2:1 to receive TLPLDC or placebo. Differences in disease-free survival (DFS) and overall survival (OS) were evaluated. RNA-seq analysis was performed on the total RNA of TLPLDC + G and TLPLDC vaccines to compare gene expression between groups. RESULTS: 144 patients were randomized: 103 TLPLDC (47 TLPLDC/56 TLPLDC + G) and 41 placebo (19 placebo/22 placebo + G). Median follow-up was 27.0 months. Both 36-month DFS (55.8% vs. 24.4% vs. 30.0%, p = 0.010) and OS (94.2% vs. 69.8% vs. 70.9%, p = 0.024) were improved in TLPLDC compared to TLPLDC + G or placebo, respectively. When compared to TLPLDC + G vaccine, RNA-seq from TLPLDC vaccine showed upregulation of genes associated with DC maturation and downregulation of genes associated with DC suppression or immaturity. CONCLUSIONS: Patients receiving TLPLDC vaccine without G-CSF had improved OS and DFS. Outcomes remained similar between patients receiving TLPLDC + G and placebo. Direct DC harvest without G-CSF had higher expression of genes linked to DC maturation, likely improving clinical efficacy.

Minimally invasive versus open distal pancreatectomy: a matched analysis using ACS-NSQIP.

BACKGROUND: Minimally invasive distal pancreatectomy (MIDP) is gaining popularity due to improved perioperative outcomes over open distal pancreatectomy (ODP). The purpose of this study is to compare outcomes of MIDP and ODP using patients within a nationwide cohort. METHODS: The American College of Surgeons' National Quality Improvement Program (2014-2018) was used to evaluate incidence of post-operative pancreatic fistula (POPF) as well as 30-day composite major morbidity for patients undergoing MIDP vs. ODP. Matching was performed with a Mahalanobis-distance model for demographic characteristics, preoperative risk factors, and benign versus malignant pathology. Outcomes were assessed via weighted multiple logistic regression. RESULTS: A total of 3940 patients underwent distal pancreatectomy (1978 MIDP, 1962 ODP). After matching, 2985 patients were included (1978 MIDP, 1007 ODP). The rates of major morbidity (8.65% MIDP vs. 9.76% ODP, p = 0.37) were similar between groups. The MIDP group was found to have significantly decreased length of stay (5.6 vs. 7 days, p ≤ 0.001), but greater rates (12.54% MIDP vs. 9.35% ODP, p = 0.02) of post-operative fistula. CONCLUSIONS: When matched for baseline patient characteristics, MIDP was associated with shorter length of hospitalization with similar rates of morbidity compared to ODP. However, MIDP was associated with significantly increased rates of POPF. Further studies are needed to investigate this difference in POPF rate, and determine how to optimize MIDP surgical technique to reduce this risk.

Circulating Tumor DNA: Towards More Individualized Treatment for Patients with Resectable Colorectal Cancer.

PURPOSE: Despite curative-intent treatment, recurrence is common for patients with colorectal cancer (CRC).  Currently, prediction of disease recurrence and prognostication following surgery is based upon vague clinical factors and more precise and dynamic biomarkers for risk stratification and treatment decisions are urgently needed.  Circulating tumor DNA (ctDNA) is a promising biomarker for patients undergoing treatment for resectable CRC. METHODS: In this review, we provide an overview of the data supporting current uses of ctDNA for CRC, including localized CRC and resectable colorectal liver metastases (CLM), as well as descriptions of important ongoing clinical trials using ctDNA in the care of patients with CRC. RESULTS: The detection of ctDNA following curative-intent therapy is associated with disease recurrence, and multiple trials are investigating its role in determining need and duration for adjuvant therapy for localized CRC. In addition, ctDNA reliably predicts prognosis for patients with CLM, with trials underway studying ctDNA-guided treatment sequencing and intensity. CONCLUSION: The detection of ctDNA is a sensitive and dynamic biomarker for disease recurrence in CRC. Many investigations are underway into ctDNA's potential role in surveillance and treatment algorithms, and it has the potential to become a critical biomarker to determine individualized strategies for treatment sequencing, choice, and duration of therapies.

The art of peer review: Guidelines to become a credible and constructive peer reviewer.

Peer review is a learned skill set that requires knowledge of study design, review construct, ethical considerations, and general expertise in a field of study. Participating in peer review is a rewarding and valuable experience in which all academic physicians are encouraged to partake. However, formal training opportunities in peer review are limited. In 2021, the Association of Women Surgeons and the journal Surgery collaborated to develop a Peer Review Academy. This academy is a 1-year longitudinal course that offers a select group of young women surgical trainees across all specialties a curriculum of monthly lectures and multiple formal mentored peer review opportunities to assist them in developing the foundation necessary to transition to independent peer review. The trainees and faculty mentors participating in the Association of Women Surgeons-Surgery Peer Review Academy compiled a summary of best peer review practices, which is intended to outline the elements of the skill set necessary to become a proficient peer reviewer.

Minimally invasive versus open hepatectomy for the resection of colorectal liver metastases: a systematic review and meta-analysis.

BACKGROUND: While surgical resection has a demonstrated utility for patients with colorectal liver metastases (CRLM), it is unclear whether minimally invasive surgery (MIS) or an open approach should be used. This review sought to assess the efficacy and safety of MIS versus open hepatectomy for isolated, resectable CRLM when performed separately from (Key Question (KQ) 1) or simultaneously with (KQ2) the resection of the primary tumor. METHODS: PubMed, Embase, Google Scholar, Cochrane CENTRAL, International Clinical Trials Registry Platform (ICTRP), and ClinicalTrials.gov databases were searched to identify both randomized controlled trials (RCTs) and non-randomized comparative studies published during January 2000-September 2020. Two independent reviewers screened literature for eligibility, extracted data from included studies, and assessed internal validity using the Cochrane Risk of Bias 2.0 Tool and the Newcastle-Ottawa Scale. A random-effects meta-analysis was performed using risk ratios (RR) and mean differences (MD). RESULTS: From 2304 publications, 35 studies were included for meta-analysis. For staged resections, three RCTs and 20 observational studies were included. Data from RCTs indicated MIS having similar disease-free survival (DFS) at 1-year (RR 1.03, 95%CI 0.70-1.50), overall survival (OS) at 5-years (RR 1.04, 95%CI 0.84-1.28), fewer complications of Clavien-Dindo Grade III (RR 0.62, 95%CI 0.38-1.00), and shorter hospital length of stay (LOS) (MD -6.6 days, 95%CI -10.2, -3.0). For simultaneous resections, 12 observational studies were included. There was no evidence of a difference between MIS and the open group for DFS-1-year, OS-5-year, complications, R0 resections, blood transfusions, along with lower blood loss (MD -177.35 mL, 95%CI -273.17, -81.53) and shorter LOS (MD -3.0 days, 95%CI -3.82, -2.17). CONCLUSIONS: Current evidence regarding the optimal approach for CRLM resection demonstrates similar oncologic outcomes between MIS and open techniques, however MIS hepatectomy had a shorter LOS, lower blood loss and complication rate, for both staged and simultaneous resections.