Orthotopic Tumor Models

Orthotopic tumors grow in the organ of origin in their natural tumor environment. The interaction with stroma cells, as well as tissue-specific immune cells, allows tumor growth similar to that of the original tumor after orthotopic implantation. Overall orthotopic tumor models feature a high predictive therapeutic value.

The interaction of tumor cells with tissue-specific stroma cells affects growth, differentiation, and drug sensitivity of tumor cells. Moreover, orthotopic tumors can metastasize with specificities comparable to the human situation. Orthotopic implantation of tumors generally requires surgery and methods for visualizing tumor growth inside the body. Our state-of-the-art IVIS bioimager yields in-depth knowledge about the growth characteristics of the orthotopic tumors.

  • Orthotopic tumors are implanted into the organ of origin.
  • Study results have high translational value.
  • Orthotopic xenograft and syngeneic tumor models are available.
Glioblastoma Study Example

Goal: Determination of the therapeutic efficacy of standard of care compound Temozolomide in the orthotopically implanted U87MG glioblastoma tumor model in vivo.

Study outline: Tumor cells of the luciferase-expressing U87MG cell line were implanted into female NMRI nude mice under anesthesia via a burr hole into the right half of the cerebrum. The growth of the glioblastoma tumor was monitored once per week via whole-body bioluminescence imaging. On day 8, mice that were bearing tumors were randomized into 3 treatment groups with 8 to 9 animals each. On the following day, treatment was initiated at either 1 mg/kg or 10 mg/kg i.v. three times per week. After euthanization, the cerebrum was isolated from the mice and homogenized for the quantification of luciferase in the tissue as a readout for tumor size.

Results:

animal weight of U87 MG tumors in a treatment testing study

Animal weight of the U87MG orthotopic tumor model is shown with vehicle and Temozolomide treatment in two doses.

 

U87 MG tumor growth after temozolomide treatment

Monitoring of U87MG tumor growth was performed once per week via whole-body bioluminescence measurement. Shown are the mean values of luciferase quantifications.

 

U87 MG tumor volume and tumor weight at endtime

At day 26, cerebrums of the sacrificed animals were isolated at necropsy and homogenized. Luciferase was quantified via enzymatic assay ex vivo. Blotted are the mean luciferase activity normalized to organ weight in the top graph and the individual luciferase readouts in the lower graph together with their median values and interquartile ranges. P values were calculated compared to the vehicle control using the unpaired t‑test.

Syngeneic Study Example

Goal: Capecitabine, a standard of care therapeutics for colon cancer, was tested for it's potential to inhibit orthotopic CT26wt primary tumor growth.

Study layout: Luciferase-expressing CT26wt cells were orthotopically implanted into the colon of Balb/C mice, at 10 mice per group. After randomization on day 2, treatments were initiated on the following day. Test compound capecitabine was administered per os at 625 mg/kg daily. Tumor growth was monitored by whole-body bioluminescence once per week, animal weight was measured three times per week, animal behavior was observed daily. On day 18, animals were euthanized and endpoint measurements for the determination of primary tumor volumes, and wet weights were performed.

 

animal weight in CT26 tumor study after orthotopic implantation

The animal weight of CT26wt orthotopic tumor model is shown with vehicle and capecitabine treatment.

orthotopic CT26 tumor model growth with capecitabine treatment

Monitoring of CT26wt tumor growth was performed once weekly via whole-body bioluminescence. Shown are the mean values of luminescence +/- SEM.

 

CT26 tumor growth individual animals with capecitabine treatment

Tumor growth is shown for individual tumors.
Green: vehicle. Purple: capecitabine (625 mg/kg) p.o. daily.

 

orthotopic CT26 tumor weight of individual animals at endpoint with capcitabine treatment

At day 18, tumors were isolated from the mice at necropsy and weighed. Blotted are the mean tumor weights in the top graph and the individual tumor weights in the lower graph together with their median values and interquartile ranges.

 

 

 

Study Layout

Standard study layout

Luciferase-based tumor models: Tumor cells are implanted into the mice (orthotopic or intravenous for tumor cell growth in the bone marrow). When appropriate luciferase signals are detected by whole-body luminescence measurement, animals are randomized in treatment groups before treatment starts. The mice are monitored on a regular basis: the tumor size is measured via whole-body luminescence measurement once weekly; animal weights are taken three times per week and animal behavior is observed daily. Once per week, we update the customer with a graphical presentation of the study progress.

Breast and skin orthotopic tumor models are monitored via calipering twice weekly. Whole-body luminescence measurement is possible in the majority of breast and skin cancer models, please see the individual datasheets for more information on luciferase expression.

Report

A comprehensive report will be prepared by a PhD-level medical writer. The report will be custom-tailored for each project with data that can be used for filing official documents. The report includes material, methods, raw data, animal health chart, and graphs plus statistical evaluation.

Selection of optional services:

  • Isolation of tumors at necropsy for determination of volume and wet weight
  • Preservation of tissue via fixation or snap-freezing
  • Histological or pathological analysis of tumor tissue and mouse body
  • Determination of expression of genes or proteins
  • Plasma sampling and bioanalysis of compound or metabolites
  • Quantification of cytokines and chemokines in blood or tissue via MESO QuickPlex SQ120 multiplex analysis
  • Flow cytometry analysis for immune cell profiling
  • MRI analysis via collaboration
  • Whole-body imaging to detect metastatic foci
  • Ex vivo luciferase measurement of organs to determine the metastatic load
Study Options

Standard Efficacy Studies: The therapeutic effect of a new drug is investigated by measuring tumor size.

Proof-of-Concept Studies: New drug candidates need to be tested not only for efficacy but also for their mechanism of action in the animal. Exploratory proof of concept studies can be performed together with histological, pathological, or molecular investigations of the biological activity of the drug on the tumor tissue.

Pharmacokinetic Studies: Pharmacokinetic studies on tumor-bearing mice are helpful in determining the concentration of drugs not just in plasma but in the tissue of the tumors.

Pharmacodynamic Studies: Pharmacodynamic studies elucidate whether and how a drug acts on its target.

Dose-Response-Relationship: Determine suitable drug doses for efficacy testing.

Drug Combination Studies: Combinations of drugs can lead to synergistic effects and vastly increased tumor response.

Survival Studies: A survival study gives data in addition to the reduction of tumor growth – it shows the number of partial and complete responders. The setup is also useful for drugs with no homogeneous response. Studies with an outcome of a mix of non-responders and responders are hard to interpret with common statistical values due to the high standard variation of the results. Survival studies can give meaningful results for such ambivalent drug candidates.

Imaging

IVIS Spectrum In Vivo Imaging System by PerkinElmer.

Using the IVIS system, we can detect and track bioluminescent and fluorescent reporters across the blue to near-infrared wavelength region. This state-of-the-art system is equipped with 10 excitation filters for detection of multiple signals in one mouse.

 

Custom Model Development

We continuously increase our portfolio of tumor models and provide custom development of new tumor models.

Cell lines: We can develop new tumor models a. based on customer-provided cell lines, b. based on a cell line from our extensive database of almost 200 cell lines or c. purchase a cell line from a commercial vendor.

Luciferase-expression: Orthotopic tumor models which do not originate from breast or skin tissue need luciferase for monitoring of tumor growth. We provide cell line generation service for stable expression of luciferase in the tumor cell line of your choice.

Two-step approach: In case no tumor-model related data are available, we will perform a two-step approach to develop a new tumor model. In the first step, we identify a suitable mouse strain for tumor growth and determine the optimal conditions for tumor cell implantation. In a second study, we will monitor the tumor growth after tumor cell implantation into 12 mice for the determination of the growth characteristics of the tumors. This two-step approach guarantees satisfactory study results for subsequent efficacy studies.

Standard of care (SOC) treatment: Most of our models were tested with a variety of standard of care treatment. Please let us know which positive control is the most suitable for your drug candidate, and we will be happy to provide historical data with SOC treatment options.

Certification

The animal facility of Reaction Biology is located in Freiburg, Germany.

Our facility is certified under ISO 9001:2015, which is an international standard that specifies requirements for the quality management system and demonstrates the ability to consistently provide products and services that meet customer and regulatory requirements. Reaction Biology is committed to continuously maintain and improve its quality management system as a key element for the achievement of the highest customer satisfaction. ISO 9001
Quality Assurance

Animal work

  • Routine health monitoring of sentinel animals (according to FELASA guidelines)
  • Standardized operation procedures are in place of every step and every model

Cell lines

  • Routine authentication of tumor cell lines by STR profiling
  • Mycoplasma testing of tumor cells by PCR just prior to implantation

Study support

  • Studys generally start (tumor implantation) 3 to 5 weeks after receipt of order
  • Suggestions for study layout to get statistically relevant results
  • Weekly study update and personal contact with study supervisor
  • Reports are written by technical writers on PhD level

Ethical principles

  • Our animal work is conducted according to the 3R (Replacement, Reduction, and Refinement)
  • We are working closely with our animal care committee to ensure timely adaptions of our animal care licenses to custom-tailor our client’s project to ensure the most meaningful study outcome
Animal Welfare

Reaction Biology uses laboratory animals to help our customers to understand the fundamental mechanisms behind malignancies and to discover therapeutics to prevent and treat cancer. Data obtained from animal models is critical predicting the clinical outcome for an oncology drug candidate in development.

Animal welfare is of the utmost importance to us. Animal-based research is highly regulated to ensure ethical and responsible treatment. The mice in our facility are specifically bred for research purposes, and they are cared for to the very high standards.

We are working under GV-SOLAS and ISO9001 regulations in regard to standards of animal welfare and code of practice.

We employ three veterinarians and appropriately trained staff to ensure animal welfare is maintained at the highest standards. Regulation officers inspect our unit regularly.

Brows our orthotopic tumor models.