Functional Profiling for Gastric Cancer

gdpawel

Functional profiling consists of a combination of a (cell morphology) morphologic endpoint (DISC) and one or more (cell metabolism) metabolic endpoinsts (MTT, ATP, resazurin). It studies cells in small clusters or microspheroids (microclusters). The combination of measuring morphologic (structural) effects and metabolic effects constitutes the measuring of a profile at the whole cell level.

Functional profiling (whole cell profiling) with cell culture assays for targeted drug therapy

Recent findings presented at the American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium in Orlando, Florida concluded that "Functional Profiling" with cell culture assays is relevant for the study of both "conventional" and "targeted" antineoplastic drug agents.

Cell Culture Assays with "cell-death" endpoints can show disease-specific drug activity, are useful clinical and research tools for "conventional" and "targeted" drugs, and provide unique information complementary to that provided by "molecular" tests. There have been more than 25 peer-reviewed publicatons showing significant correlations between cell-death assay results and patient response and survival.

The "Functional Profiling" technique is a cell-death endpoint assay in which drug effect upon cancer cells is visualized directly. Photomicrographs of actual tumor cells sometime show that the exact same identical individual culture well, shows some clusters have taken up vast amounts of a drug, while right next door, clusters of the same size, same appearance, same everything haven't taken up any of the drug.

So it doesn't matter if there is a "target" molecule (protein or receptor) in the cell that the targeted drug is going after, if the drug either won't "get in" in the first place or if it gets pumped out/extruded or if it gets immediately metabolized inside the cell, drug resistance is multifactorial. The advantage of the "Functional Profiling" technique is that it can show this in the "population" of cells.

The "Functional Profiling" technique makes the statistically significant association between prospectively reported test results and patient survival. It can correlate test results which are obtained in the lab and reported to physicians prior to patient treatment, with significantly longer or shorter overall patient survival depending upon whether the drug was found to be effective or ineffective at killing the patient's tumor cells in the laboratory.

This could help solve the problem of knowing which patients can tolerate costly, new treatments and their harmful side-effects. These "smart" drugs are a really exciting element of cancer medicine, but do not work for everyone, and a test to determine the efficacy of these drugs in a patient could be the first crucial step in personalizing treatment to the individual.

Functional profiling (FP) with cell culture assays for targeted drug therapy.
Sub-category: Translational research
Category: Colon and Rectum
Meeting: 2007 Gastrointestinal Cancers Symposium

Abstract No: 440
Author(s): L. M. Weisenthal

Abstract: Introduction: We studied the relevance of FP for standard and targeted drugs.

Methods: Drugs were tested against fresh human tumor microclusters, with 96 hr drug exposures and multiple FP endpoints (MTT, DISC, resazurin, and/or ATP).

Results: In 65 previously chemonaive stage 4 colon cancer patients, those with FP assays showing 5FU results in the most resistant tertile had inferior overall survival, compared to pts without 5FU resistance (303 days vs. 686 days, H.R. 2.1, 95% C.I. 1.2 - 5.0, P2=0.011). In subset analysis restricted only to 53 pts who subsequently died (eliminating potential surgical cures), the respective results were 292 vs 493 days, HR 1.5 - 6.9, P2=0.0021. We applied FP to test targeted agents, including gefitinib, erlotinib, sunitinib, sorafenib, and bevacizumab. Gefitinib was tested against > 700 fresh tumor specimens; we reported striking correlations between gefitinib activity and overall pt survival in non-small lung cancer (2006 ASCO Annu Mtg, Abst 17117). Gefitinib and erlotinib are moderately cross resistant (R2=0.48, n paired comparisons=190). Gefitinib/sunitinib (R2=0.20, n=46) and erlotinib/sunitinib (R2=0.12, n=44) are largely non-cross resistant. We also developed a new microvascular viability assay (MVVA) to test microvascular cells present in tumor clusters. In the MVVA, bevacizumab was tested in 81 fresh tumor specimens (including 15 GI). Bevacizumab was nontoxic to the tumor cells, but often strikingly toxic to microvascular cells present within the same tumor clusters. Grading on a 0-4 scale, there was absent (Gr 0) effect in 23 specimens, weak (Gr 1-2) effect in 28, and a strong (Gr 3-4) effect in 26. In contrast to bevacizumab, neither sunitinib (n=87) nor sorafenib (n=20) showed selective effects against microvascular cells compared to tumor cells.

Conclusions: We cannot rule out a cytostatic effect of sunitinib or sorafenib on tumor microvascular cells. However, our results imply that the antitumor effects of bevacizumab are predominately mediated through antimicrovascular effects, while effects of sunitinib and sorafenib may be mediated largely through tumor cell apoptosis. We conclude that FP is relevant for the study of both traditional and targeted antineoplastic agents.

gdpawel

Is there more to Gastrointestinal Cancer Managment than FOLFOX?
[Dr. Nagourney is medical and laboratory director at Rational Therapeutics, Inc., in Long Beach, California, and an instructor of Pharmacology at the University of California, Irvine School of Medicine. He is board-certified in Internal Medicine, Medical Oncology and Hematology]

One example of the functional tumor cell profiling approach represents a novel opportunity to explore the biology of gastic cancer.

Case Report

A 58-year-old male with a very bad diagnosis — a bout of gastrointestinal bleeding that had lead to an upper GI endoscopy. It wasn’t an ulcer, or even gastric cancer, but a very rare form of cancer arising in the duodenum. Adenocarcinoma of the duodenum is very uncommon.

In addition to the bleeding, he had lost a substantial amount of weight, was in pain and had a very large tumor that was nearly obstructing his upper GI tract. After getting the patient stabilized, he was referred to a surgeon who conducted an aggressive surgical resection. The recovery was difficult, prolonged and accompanied by additional GI bleeding. By the time the patient had recovered adequately enough to consider additional therapy, his PET scan revealed extensive re-growth.

If you were to ask medical oncologists in the United States what to give such a patient, 99% would recommend FOLFOX or some variation thereof. But, FOLFOX wasn’t the right treatment for this patient. Instead, he had a strong signal for Irinotecan, which was further enhanced by the addition of an EGFR inhibitor. Based on this, the patient was treated with Erbitux + Irinotecan. Before starting therapy, his CA 19-9 was 354. Although his signal for the EGFr inhibitor was very favorable in the cell function analysis, he was screened for K-ras mutation. It seemed evident from his dose response curves and clear synergy between Irinotecan and the EGFR inhibitors that he would be K-ras wild type.

Indeed, he was K-ras wild type and was treatment was started with Erbitux + Irinotecan. Other than the rash associated with the Erbitux, the tolerance was good. The bleeding stopped immediately, the CA 19-9 plummeted with the first dose to 71 and the patient then returned every other week for therapy.

Three cycles later, the PET/CT was repeated. The phrase “marked interval regression” of measurable disease was noted. Also noted was the normalization of his CA 19-9. The patient had gained weight and returned to normal activities. With the exception of a small and diminishing rash, he looks quite normal. In fact, with the rather modest dose of Irinotecan used in his schedule, he hasn’t even suffered any hair loss.

What is most interesting about this patient is that FOLFOX, the most widely used regimen in this setting, wasn’t anywhere on the radar screen. It wasn’t active, it wasn’t recommended and wouldn’t have worked. However popular FOLFOX may have come to be in patients like this, it doesn’t fit everyone.

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