Antibiotic Exposure and Anti-PD-1 Outcomes in Advanced Melanoma

Association of antibiotic treatment with survival outcomes in treatment-naïve melanoma patients receiving immune checkpoint blockade

This multicentre melanoma cohort directly addresses antibiotic exposure around anti-PD-1 initiation and survival. Its finding that pretreatment, but not on-treatment, antibiotics were associated with worse outcomes makes exposure timing and immortal time bias particularly relevant to the draft.

How to position yourself: Cite it as closely related evidence distinguishing pretreatment from on-treatment exposure; the draft combines a fixed peri-initiation window and additionally evaluates objective response.

From its abstract: Antibiotic exposure prior to ICB was associated with worse PFS

Association of Antibiotic Exposure With Survival and Toxicity in Patients With Melanoma Receiving Immunotherapy

This melanoma cohort found an adjusted association between antibiotics before immunotherapy and worse overall survival, supporting the draft's principal survival finding. It included stage III disease and evaluated colitis as well as survival.

How to position yourself: Cite it as prior melanoma-specific evidence linking pretreatment antibiotics to worse survival; the draft focuses on advanced melanoma receiving anti-PD-1 and includes early post-initiation exposure and objective response.

From its abstract: A window of antibiotic receipt within 3 months prior to the first infusion of ICI was prespecified.

The Association Between Antibiotic Use and Outcome Among Metastatic Melanoma Patients Receiving Immunotherapy

This large advanced-melanoma cohort found no association between pretreatment antibiotics and overall survival after propensity-score overlap weighting, contrasting with the draft. Its targeted-therapy control cohort also addresses whether associations might reflect confounding rather than an immunotherapy-specific effect.

How to position yourself: Cite it as important contradictory evidence with stronger attention to confounding; the draft uses a smaller hospital cohort, a peri-initiation exposure window, and objective response assessment.

From its abstract: Antibiotic exposure in the 3 months prior to anti-PD-1 antibody initiation was not associated with shorter overall survival

Antibiotics are associated with decreased progression-free survival of advanced melanoma patients treated with immune checkpoint inhibitors

This smaller advanced-melanoma study directly examined antibiotic exposure near checkpoint-inhibitor initiation, response, and survival. It reported poorer response and progression-free survival, but the overall-survival difference was not statistically significant.

How to position yourself: Cite it as early melanoma-specific evidence of poorer response and progression-free survival; the draft has a larger multicentre anti-PD-1 cohort and a broader pretreatment window.

From its abstract: Overall survival (OS) was also shorter; however, this was not statistically significant

Use of antibiotics is associated with worse clinical outcomes in patients with cancer treated with immune checkpoint inhibitors: A systematic review and meta-analysis

This systematic review and meta-analysis synthesizes observational evidence linking antibiotics with poorer checkpoint-inhibitor response and survival, including melanoma studies. Its substantial heterogeneity is relevant to interpreting the draft's association without assuming causality.

How to position yourself: Cite it for the existing pooled evidence and its heterogeneity; the draft contributes a melanoma-specific multicentre cohort with a defined peri-initiation exposure window.

From its abstract: Use of antibiotics was associated with shorter overall survival [hazard ratio (HR) 1.88, 95% confidence interval (CI) 1.59-2.22

Multivariable Analysis of 169 Cases of Advanced Cutaneous Melanoma to Evaluate Antibiotic Exposure as Predictor of Survival to Anti-PD-1 Based Immunotherapies

This advanced cutaneous melanoma cohort evaluated antibiotics as a predictor of outcomes with anti-PD-1-based therapy. Its multivariable finding of no survival association directly contrasts with the draft's adjusted overall-survival result.

How to position yourself: Cite it as conflicting melanoma-specific evidence; the draft has a larger multicentre cohort and also examines objective response within a specified antibiotic window.

From its abstract: Contrary to some prior studies BMI, radiation, and antibiotics were not associated with PFS or OS.

The commensal microbiome is associated with anti–PD-1 efficacy in metastatic melanoma patients

This paper supplies directly relevant biological motivation by relating the gut microbiome to anti-PD-1 response in metastatic melanoma. It supports the microbiome-response premise rather than directly establishing the clinical consequences of antibiotic exposure in melanoma.

How to position yourself: Cite it for human melanoma evidence connecting gut microbial composition with response; the draft evaluates antibiotic exposure as an indirect clinical marker rather than measuring the microbiome.

From its abstract: Matson et al. and Gopalakrishnan et al. studied melanoma patients receiving PD-1 blockade and found a greater abundance of “good” bacteria in the guts of responding patients.

Antibiotic Treatment is an Independent Poor Risk Factor in NSCLC But Not in Melanoma Patients Who had Received Anti-PD-1/L1 Monotherapy

This multicentre study included a directly relevant melanoma cohort receiving anti-PD-1/L1 monotherapy and antibiotics before or shortly after initiation. Its melanoma survival association did not remain independent in multivariable analysis, contrasting with the draft.

How to position yourself: Cite it as conflicting adjusted melanoma evidence and a warning about confounding; the draft uses a shorter pretreatment window and additionally evaluates objective response.

From its abstract: In multivariable analyses, ABT was not an independent risk-factor for inferior OS and PFS in melanoma

Impact of antibiotics on survival outcomes and risk of gastritis/colitis in patients with advanced-stage melanoma receiving anti-PD-1 therapy.

This conference abstract describes a closely related retrospective advanced-melanoma cohort examining antibiotic timing and spectrum during anti-PD-1-based treatment. The supplied abstract reports methods but not results, so it cannot establish whether its findings agree with the draft.

How to position yourself: Cite it as closely overlapping work on antibiotic timing and spectrum, while distinguishing the draft's multicentre design and objective-response endpoint from its single-centre survival and gastritis/colitis analyses.

From its abstract: Antibiotic timing was assessed as patients who received antibiotics within 30-days prior to starting ICI and/or during treatment.

Cumulative Antibiotic Use Significantly Decreases Efficacy of Checkpoint Inhibitors in Patients with Advanced Cancer

This retrospective study links peri-treatment antibiotics to poorer checkpoint inhibitor outcomes and includes a substantial melanoma subgroup. Its assessment of cumulative exposure provides important context for the draft's binary exposure classification.

How to position yourself: Cite for prior clinical evidence and exposure-duration effects; the draft examines a larger melanoma-only cohort across three hospitals using a different exposure window.

From its abstract: Antibiotic use (both single and multiple courses/prolonged use) during the periods 2 weeks before and 6 weeks after ICI treatment was investigated.

The impact of antibiotics on efficacy of immune checkpoint inhibitors in malignancies: A study based on 44 cohorts

This meta-analysis synthesizes the same antibiotic–checkpoint inhibitor association across cancers, including melanoma. Its findings on response and survival establish that the draft addresses an existing clinical evidence base.

How to position yourself: Cite for pooled evidence of poorer outcomes associated with antibiotics; the draft contributes a melanoma-specific multicenter cohort rather than a cross-cancer synthesis.

From its abstract: Totally, 12,492 individuals in the 44 cohorts were recruited.

Association of Prior Antibiotic Treatment With Survival and Response to Immune Checkpoint Inhibitor Therapy in Patients With Cancer

This prospective multicenter cohort examines antibiotic exposure, response, and survival during checkpoint inhibition and includes melanoma patients. Its differing findings for prior versus concurrent antibiotics are particularly relevant to the draft's combined exposure window.

How to position yourself: Cite for evidence that exposure timing matters; the draft is retrospective, melanoma-specific, and combines pre-initiation and early post-initiation exposure.

From its abstract: To evaluate whether there is an association between ATB therapy administered concurrently (cATB) or prior (pATB) to ICI therapy and overall survival

Abstract C055: Gene Expression Profiling Identifies a Five-Gene Signature Associated with Antibiotic Exposure and Reduced Anti–PD-1 Efficacy in Metastatic Melanoma

This conference abstract addresses prior antibiotics and survival in metastatic melanoma treated with anti-PD-1 monotherapy, closely matching the draft's question. It additionally investigates immune gene expression, although the supplied abstract does not provide complete results.

How to position yourself: Cite as closely related melanoma-specific work incorporating gene expression; the draft has a larger multicenter cohort and explicitly evaluates objective response.

From its abstract: Eighty-seven patients with inoperable metastatic melanoma treated with anti–PD-1 monotherapy were retrospectively analyzed.

The effect of antibiotics on the clinical outcomes of patients with solid cancers undergoing immune checkpoint inhibitor treatment: a retrospective study

This retrospective cohort reports lower objective response and shorter survival with antibiotics before checkpoint inhibition. Its 60-day pre-treatment window directly overlaps the draft's exposure definition.

How to position yourself: Cite for prior response and survival associations using a 60-day pre-treatment window; the draft focuses on melanoma and also captures the first 30 treatment days.

From its abstract: The data of patients who received antibiotics within 60 days before the initiation of ICI treatment were analyzed.

Negative association of antibiotics on clinical activity of immune checkpoint inhibitors in patients with advanced renal cell and non-small-cell lung cancer

This study provides early clinical evidence linking antibiotics near checkpoint inhibitor initiation to poorer survival. It addresses the same exposure–outcome hypothesis in renal cell carcinoma and lung cancer rather than melanoma.

How to position yourself: Cite for foundational clinical associations in other cancers; the draft tests their applicability to a melanoma-only anti-PD-1 cohort.

From its abstract: Those receiving ATB within 30 days of beginning ICI were compared with those who did not.

Impact of antibiotics on survival outcomes and risk of gastritis/colitis in advanced-stage melanoma patients receiving immune checkpoint inhibitor therapy

This melanoma cohort reports improved survival with antibiotics during checkpoint inhibitor treatment, providing a competing result. Its timing- and spectrum-specific analyses caution against treating all antibiotic exposure as equivalent.

How to position yourself: Cite for conflicting melanoma evidence and exposure heterogeneity, noting its Figshare status; the draft uses a larger multicenter cohort and a fixed peri-initiation window.

From its abstract: Unlike previous studies, we found improved survival in patients receiving antibiotics during treatment and in those receiving antibiotics without anaerobic coverage.

Gut microbiome influences efficacy of PD-1–based immunotherapy against epithelial tumors

This study connects antibiotic exposure and PD-1 outcomes with microbiome findings and experimental restoration of treatment response. It supplies a central biological and clinical foundation for the draft's hypothesis.

How to position yourself: Cite for mechanistic and clinical evidence linking gut microbes to PD-1 efficacy; the draft evaluates antibiotic-associated outcomes specifically in melanoma without microbiome experiments.

From its abstract: Oral supplementation of the bacteria to antibiotic-treated mice restored the response to immunotherapy.

A systematic review and meta-analysis evaluating the impact of antibiotic use on the clinical outcomes of cancer patients treated with immune checkpoint inhibitors

This large systematic review directly synthesizes antibiotic associations with checkpoint inhibitor response and survival. Its cancer-type and exposure-window analyses are important for positioning the draft's melanoma-specific contribution.

How to position yourself: Cite for the broad pooled clinical evidence and variation by exposure window; the draft adds a focused multicenter melanoma cohort.

From its abstract: 107 articles reporting data for 123 independent cohorts were included, representing a total of 41,663 patients

Antibiotic Usage Reduced Overall Survival by over 70% in Non-small Cell Lung Cancer Patients on Anti-PD-1 Immunotherapy

This NSCLC cohort examined a similar peri-initiation antibiotic window and the same response and survival outcomes. Its disease setting differs, and antibiotic exposure was not an independent predictor of overall survival in its multivariable analysis.

How to position yourself: Cite it as cross-cancer observational evidence concerning peri-initiation antibiotics, while distinguishing the draft's melanoma population and adjusted overall-survival association.

From its abstract: Eighteen out of 69 patients received antibiotics within 21 days before or within 21 days after start of anti-PD-1 therapy.

Use of broad-spectrum antibiotics impacts outcome in patients treated with immune checkpoint inhibitors

This small advanced-cancer cohort linked antibiotics near checkpoint-inhibitor initiation with worse response and survival. Its distinction between broad- and narrow-spectrum antibiotics suggests an exposure characteristic that the draft could examine.

How to position yourself: Cite it as earlier peri-initiation evidence suggesting that antibiotic spectrum may matter; the draft instead studies a larger melanoma-specific anti-PD-1 cohort.

From its abstract: Sixty consecutive patients were identified, and 17 received systemic antibiotics within 2 weeks before and/or after first dose of ICI.

Antibiotics are associated with attenuated efficacy of anti-PD-1/PD-L1 therapies in Chinese patients with advanced non-small cell lung cancer

This NSCLC cohort found shorter progression-free and overall survival with concomitant antibiotics during anti-PD-1-based treatment. It offers cross-cancer support for the draft's hypothesis but does not resolve the melanoma-specific question.

How to position yourself: Cite it as supporting observational evidence from NSCLC; the draft focuses on melanoma and a prespecified exposure window around the first infusion.

From its abstract: Concomitant Abx treatment was significantly associated with shorter progression-free survival (PFS)

Effect of Antibiotic Use on Outcomes with Systemic Therapies in Metastatic Renal Cell Carcinoma

This renal-cell carcinoma study used an antibiotic window closely resembling the draft's and reported poorer response and progression-free survival with checkpoint inhibitors. Its additional cohorts receiving other systemic therapies provide a useful comparative design.

How to position yourself: Cite it for analogous peri-initiation exposure definitions and cross-cancer findings; the draft tests the association specifically in advanced melanoma treated with anti-PD-1.

From its abstract: antibiotic use (defined as use from 8 wk before to 4 wk after the initiation of anticancer therapy)

Impact of Antibiotic Exposure Before Immune Checkpoint Inhibitor Treatment on Overall Survival in Older Adults With Cancer: A Population-Based Study

This population-based study examined pretreatment antibiotics and checkpoint-inhibitor survival in older adults across cancers. Its antibiotic-class and duration analyses offer useful context, although its population and exposure periods differ from the draft's.

How to position yourself: Cite it for population-level evidence and possible variation by antibiotic class and duration; the draft focuses on melanoma, includes early post-initiation exposure, and assesses response.

From its abstract: We performed a population-level retrospective cohort study to evaluate the impact of antibiotic exposure before starting ICI on overall survival (OS).

Impact of prior antibiotic use on the efficacy of nivolumab for non‑small cell lung cancer

This NSCLC nivolumab cohort examined prior antibiotics and survival, finding unadjusted differences but no statistically significant multivariable association. It provides related evidence that apparent antibiotic effects may weaken after adjustment.

How to position yourself: Cite it for cross-cancer evidence illustrating the importance of adjustment; the draft studies melanoma and reports an association persisting after its selected covariate adjustment.

From its abstract: However, in multivariate analysis, no statistically significant association was indicated between survival and prior antibiotic use

367 Association between antibiotic exposure and clinical outcomes of immune checkpoint inhibitor therapy: a retrospective study

This conference abstract examines antibiotic exposure during checkpoint inhibition, including response and survival outcomes. Its landmark analysis highlights potential survivor bias relevant to exposure occurring after the draft's first infusion.

How to position yourself: Cite for related on-treatment exposure research and a survivor-bias sensitivity analysis; the draft restricts exposure to a peri-initiation window in melanoma.

From its abstract: A 90-day landmark analysis assessed potential survivor bias. Secondary analyses examined antibiotic route, spectrum, duration, and number of courses among exposed patients.

The Gut Microbiome Associates with Immune Checkpoint Inhibition Outcomes in Patients with Advanced Non–Small Cell Lung Cancer

This prospective lung cancer study relates baseline antibiotics to measured microbiome alterations and examines microbiome associations with checkpoint inhibitor outcomes. It supports the proposed biological pathway but does not establish that pathway in the draft's melanoma cohort.

How to position yourself: Cite for microbiome evidence accompanying antibiotic exposure; the draft studies clinical associations in melanoma without reported stool profiling.

From its abstract: Patients who received pre-ICI antibiotic had lower alpha diversity at baseline and underrepresentation of Ruminococcaceae UCG 13 and Agathobacter.

Antibiotics are associated with worse outcomes in lung cancer patients treated with chemotherapy and immunotherapy

This large lung cancer study evaluates antibiotic exposure using pre-treatment and combined peri-treatment windows, with the same principal clinical outcomes as the draft. Its inclusion of chemo-immunotherapy limits direct comparability.

How to position yourself: Cite for analogous exposure-window analyses and clinical associations in lung cancer; the draft concerns melanoma treated with anti-PD-1 antibodies.

From its abstract: within 60 days prior to therapy and 42 days after therapy (-60 + 42d window)

Disrupting the microbiome, disrupting immunity: Antibiotic exposure and survival outcomes with immune checkpoint inhibitors—A systematic review.

This conference systematic review summarizes predominantly adverse survival associations across solid tumors while acknowledging exceptions. It provides recent context but is less directly informative than melanoma-specific cohorts or the larger full meta-analysis supplied.

How to position yourself: Cite for a recent overview of consistency and exceptions across cancers; the draft supplies original melanoma-specific response and survival data.

From its abstract: Antibiotic exposure within 30–60 days before or during ICI therapy was associated with inferior overall survival (OS) in the majority of studies.

Association between antibiotic-immunotherapy exposure ratio and outcome in metastatic non small cell lung cancer

This lung cancer cohort finds different associations depending on whether exposure is defined early in treatment or as cumulative antibiotic exposure relative to treatment duration. It suggests that the draft's binary peri-initiation definition may miss relevant exposure patterns.

How to position yourself: Cite for timing- and exposure-burden-dependent findings; the draft examines melanoma using a fixed binary exposure window rather than an exposure ratio.

From its abstract: No differences in either Progression-Free Survival (PFS) or Overall Survival (OS) were observed according to antibiotic use during the EIOP

The effects of antibiotics on the efficacy of immune checkpoint inhibitors in patients with non–small-cell lung cancer differ based on PD-L1 expression

This multicenter lung cancer cohort uses essentially the same antibiotic exposure window as the draft and reports shorter overall survival but no significant progression-free survival difference. It also examines variation by PD-L1 expression.

How to position yourself: Cite for an analogous peri-initiation exposure definition and qualified survival findings; the draft tests response and overall survival in melanoma rather than lung cancer.

From its abstract: Outcomes with use of ATBs during the 2 months before or a month after initiation of ICI treatment