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Subrenal capsule assay of fresh human tumors: problems and pitfalls
Abstract:
The 6 day subrenal capsule (SRC) assay was performed in normal mice using 20 fresh human non-small cell lung cancers and nine fresh ovarian cancers. Different multi-agent chemotherapy regimens administered intravenously on days 2 + 3 of the assay were evaluated for activity against these two tumor types. Macroscopic results measured via an ocular microscope showed high activity for some combinations as well as for single agents. However, when subjected to microscopic examination, the SRC implants in the untreated control animals did not show viable tumor growth on day 6. Detailed histologic evaluation of over 800 SRC grafts reveals an intense inflammatory and fibrotic reaction in the majority of the grafts. These results indicate that drug sensitivity patterns obtained with this assay using only macroscopic criteria do not correlate with actual tumor regression. Microscopic analysis of the grafts prior to transplant shows absence or only minimal presence of tumor in many cases which also contributes to the poor growth observed in these two tumors.
Insights
The subrenal capsule (SRC) assay for cancer drug testing showed promising results macroscopically, but microscopic evaluation revealed it is unreliable for predicting chemotherapy effectiveness in non-small cell lung and ovarian cancers.
Area of Science:
- Oncology
- Experimental Therapeutics
- Cancer Research
Background:
- The subrenal capsule (SRC) assay is a xenograft model used to evaluate anti-cancer drug efficacy.
- Accurate prediction of chemotherapy response is crucial for effective cancer treatment.
Purpose of the Study:
- To assess the reliability of the 6-day SRC assay in predicting chemotherapy response for human non-small cell lung cancers and ovarian cancers.
- To investigate the correlation between macroscopic and microscopic evaluations of tumor growth in the SRC assay.
Main Methods:
- The 6-day SRC assay was performed in normal mice using fresh human non-small cell lung cancers (n=20) and ovarian cancers (n=9).
- Mice received multi-agent chemotherapy regimens intravenously on days 2 and 3 of the assay.
- Tumor growth was evaluated macroscopically using an ocular microscope and microscopically via histologic examination.
Main Results:
- Macroscopic evaluation suggested high activity for some chemotherapy regimens and single agents.
- Microscopic examination revealed no viable tumor growth in untreated control animals on day 6.
- Histologic evaluation of over 800 grafts showed intense inflammatory and fibrotic reactions, indicating poor tumor establishment and growth.
Conclusions:
- Macroscopic assessment of the SRC assay does not correlate with actual tumor regression.
- The assay's reliability is compromised by a high incidence of inflammatory and fibrotic reactions and poor tumor engraftment.
- The SRC assay, using only macroscopic criteria, is not a suitable method for determining drug sensitivity patterns in non-small cell lung and ovarian cancers.