LBP + PD-1/PD-L1 Synergy Efficacy Models in Murine Tumors

Strategic Approach to LBP and ICI Co-Therapy

Who this service is for

You have an LBP candidate and need preclinical proof-of-concept (PoC) for combination with PD-1/PD-L1.
You need to systematically pick the best ICI partner or optimize the dosing schedule.
You want to generate clear biomarker hypotheses to guide clinical translation.
You need robust, highly-controlled data for partnering discussions or IND-enabling packages.

The revolution in immuno-oncology, primarily driven by Immune Checkpoint Inhibitors (ICIs), has transformed cancer treatment. However, a significant clinical pain point persists: a large subset of patients exhibit primary or acquired resistance. Preclinical and clinical evidence strongly indicates that the host microbiome serves as a crucial rheostat for systemic immune responses, effectively dictating whether a "cold" tumor environment can be converted into a "hot," inflamed, and immunotherapy-responsive state.

Creative Biolabs addresses this critical bottleneck by offering specialized, strictly controlled syngeneic murine tumor models. We design and execute pharmacology studies combining strict anaerobic or aerobic LBPs with systemic checkpoint blockades. Our tailored study designs aim to establish preclinical proof-of-concept, translating your microbial potential into actionable, IND-ready efficacy data.

Core Deliverables and Analytical Outputs

We deliver publication-quality datasets that provide the mechanistic rationale and statistical proof behind your LBP's synergistic effects.

Quantitative Synergy Statistics

Synergy assessment options: Bliss independence, Highest Single Agent (HSA), or response-surface modeling (as appropriate for in vivo endpoints).

Outputs: Synergy score (with Confidence Intervals), interaction p-value, and interpretation (synergistic / additive / antagonistic).

Value: Designed to support partnering decks and IND-enabling narratives (combining efficacy, robust statistics, and biomarker rationale).

Tumor Growth Inhibition (TGI) Kinetics

Blinded longitudinal measurements of tumor volumes using high-precision digital calipers or non-invasive in vivo imaging systems (IVIS). Deliverables include TGI percentage calculations, individual/group mean tumor growth curves, and Kaplan-Meier survival analysis tracking long-term durability against appropriate baselines.

Comprehensive Immune Cell Profiling

Multi-color flow cytometry (FACS) on tumor-infiltrating lymphocytes (TILs), draining lymph nodes, spleen, and intestinal tissues. We output quantitative data on CD8+ T cell activation (e.g., Granzyme B, IFN-γ expression), CD8+/Treg ratio shifts, and the modulation of suppressive populations (MDSCs/TAMs).

Soluble Biomarker and Cytokine Arrays

Utilizing multiplexed ELISA or Luminex platforms to quantify systemic and localized cytokine profiles from serum or tumor homogenates. We track critical immuno-modulatory signals (IFN-γ, TNF-α, IL-2, IL-10, IL-6) to provide a molecular roadmap of how your LBP successfully primes the immune system.

Optimized Study Design and Workflow

We execute highly customized study protocols structured to evaluate precise synergy and eliminate confounding variables.

Group Designation	Treatment Regimen	Purpose in Synergy Model
Group 1: Vehicle Control	Oral buffer (LBP vehicle) + IP Isotype Control Antibody	Establishes the baseline exponential tumor growth kinetics and natural survival curve of the chosen syngeneic model.
Group 2: LBP Monotherapy	Oral LBP formulation + IP Isotype Control Antibody	Determines the independent immunomodulatory baseline capability of the Live Biotherapeutic alone.
Group 3: ICI Monotherapy	Oral buffer + IP Anti-PD-1 or Anti-PD-L1 Antibody	Establishes the standard-of-care baseline. Crucial for identifying the extent of non-responsiveness inherent to the specific tumor model.
Group 4: Combination (Synergy)	Oral LBP formulation + IP Anti-PD-1 or Anti-PD-L1 Antibody	The primary test group. Compares tumor regression and immunological shifts directly against Groups 2 and 3 to evaluate synergistic efficacy.

Crucial Control Points for Microbiome Research

To ensure reproducibility and rigorous proof-of-concept in LBP-immune modeling, we strictly control key variables:

01

Randomization & Blinding

Strict mouse strain, sex, and age randomization, coupled with blinded tumor volume measurements to remove observer bias.

02

Housing & Cage Effects

Careful consideration of coprophagy and cage-clustering effects, which are critical confounders in any microbiome-based in vivo study.

03

Antibiotic Pre-conditioning

Controlled and justified antibiotic clearing regimens (optional) followed by precise washout periods to facilitate LBP engraftment.

04

LBP Viability Confirmation

Pre- and post-dosing CFU verification to ensure exact dosage and stability windows for live, especially strict anaerobic, organisms.

05

ICI Dosing Justification

Expert guidance on ICI dosage, route, and frequency matched to the tumor model's baseline responsiveness.

06

Pharmacodynamic Timing

Sample collection timelines tightly aligned with immune activation kinetics to capture transient biomarker shifts.

Unmatched Preclinical LBP Capabilities

We bridge the gap between microbiology and advanced oncology. Handling live, often strictly anaerobic microorganisms while concurrently running complex immunological in vivo models requires a highly specialized infrastructure.

Extensive Tumor Model Library

Access a broad repository of syngeneic models including MC38 (colon adenocarcinoma), CT26 (colon carcinoma), B16-F10 (melanoma), and EMT6 (breast cancer). We guide you in selecting models based on their inherent immunogenicity, baseline T-cell infiltration, and historical responsiveness to PD-1/PD-L1 blockades to ensure a suitable therapeutic assay window for your LBP.

Strict Anaerobic Preservation

Unlike standard CROs, our facility is equipped to handle highly sensitive, strictly anaerobic gut commensals (e.g., Akkermansia, Faecalibacterium, Bacteroides species). We utilize anaerobic chambers for dose formulation and ensure high viability immediately prior to animal administration, avoiding false negatives caused by compromised viability.

Advanced Ex Vivo Analytics

Our pharmacology models are supported by an integrated immunology laboratory. We seamlessly transition from in vivo tissue harvest to rapid ex vivo single-cell suspensions. This guarantees high-viability immune cell preservation for precise multi-parameter flow cytometry, transcriptomics, and spatial profiling of the tumor microenvironment.

Published Data: Microbiome and ICI Synergy in Preclinical Oncology

The foundational rationale for developing LBPs as oncology adjuvants is deeply rooted in high-impact preclinical research. Landmark investigations have reshaped our understanding of the tumor microenvironment by revealing the indispensable role of the gastrointestinal microbiota in mediating responses to immunotherapy.

For instance, seminal studies have demonstrated that the oral administration of specific commensal strains (such as Bifidobacterium species) alone can delay melanoma tumor growth, providing tumor control comparable to targeted PD-L1 specific antibody therapy. More critically for synergy evaluation, the concurrent administration of these beneficial commensal bacteria alongside anti-PD-L1 therapy substantially reduced tumor growth in reported models compared to monotherapy.

This synergistic effect is largely attributed to the microbial capability to augment dendritic cell function, subsequently enhancing CD8+ T cell priming and accumulation within the tumor microenvironment. These established biological mechanisms form the rigorous framework underpinning the in vivo testing and validation platforms offered by Creative Biolabs.

Bifidobacterium improves response to αPD-L1 in established tumors. (Creative Biolabs Authorized)

Fig.1 Direct administration of Bifidobacterium to TAC recipients with established tumors improves tumor-specific immunity and response to αPD-L1 mAb therapy.^1,3

Seamlessly Integrate Your Synergy Studies

A successful LBP immuno-oncology program requires holistic data. Beyond macroscopic tumor measurements, understanding the exact cellular and molecular mechanisms driving your product's efficacy is paramount. We recommend integrating our synergy in vivo models with our specialized downstream analytical services to build an unassailable data package for regulatory submission.

Frequently Asked Questions

For many programs, MC38 and CT26 provide a useful therapeutic window with measurable baseline response to PD-1/PD-L1 blockade—supporting detection of incremental benefit from an LBP. For “cold-to-hot” conversion hypotheses, more ICI-refractory models such as B16-F10 can be informative but may require careful endpoint planning.

For strict anaerobes, dose preparation can be performed using oxygen-controlled workflows, and CFU-based viability verification can be included to confirm that live organisms were delivered at the intended dose.

We can support antibiotic pre-conditioning in SPF mice as an optional strategy to facilitate engraftment and reduce background variability. If you require deeper microbiome control, discuss your requirements with our scientists so we can align the operational approach to your study goals.

Commonly informative readouts include CD8 effector activation markers, CD8/Treg ratio, dendritic cell activation in draining lymph nodes, myeloid suppressor populations (MDSCs/TAMs), and systemic/tumor cytokines associated with Th1-skewed immunity. Final selection should reflect your LBP MoA and planned clinical translation.

At minimum: LBP identity (strain/consortium), formulation and dose range (target CFU), proposed route and schedule, expected MoA, preferred ICI target (PD-1 vs PD-L1), and any prior in vitro/in vivo data. If you have constraints on mouse strain/sex or sampling needs, we’ll incorporate them into the design.

Other Resources

Creative Biolabs' Live Biotherapeutics - Brochure

Probiotic Strain Products for NGP Research - Brochure

Custom Small-scale Probiotic Production - Brochure

Live Biotherapeutics - Creative Biolabs - Video

References

Sivan, Ayelet, et al. "Commensal Bifidobacterium promotes antitumor immunity and facilitates anti–PD-L1 efficacy." Science 350.6264 (2015): 1084-1089. https://doi.org/10.1126/science.aac4255
Gopalakrishnan, Vancheswaran, et al. "Gut microbiome modulates response to anti–PD-1 immunotherapy in melanoma patients." Science 359.6371 (2018): 97-103. https://doi.org/10.1126/science.aan4236
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