Stratification of likely responders based on individualized kinetic optical response profiling of therapy options in freshly isolated short-term tumor cultures
Authors: W. David Hankins, P. M. Grimley, W. I. Smith, D. Zhang, D. M. Williams
Journal: Clinical Cancer Research (2006)

PL-11   In both the clinical development of new anticancer drugs and for patient care with current therapy options, the need for defining which patients are likely to respond to a given drug is paramount. This is because most oncology drugs are only effective in 10-30% of the patients and even potent responses are often short-lived and fail to produce a cure. There are a few molecular biomarkers, e.g. her2, and CD20 for trastuzumab and rituximab, respectively, that can be used for pre-selecting likely responders. However, for the majority of drugs, biomarkers which predict therapeutic efficacy do not exist. For such drugs, the only way to determine potential efficacy is through case-based trial and error or through expensive and time-consuming clinical trials, involving hundreds of patients. Therefore, methods of stratifying patients as likely responders or non-responders are needed.Our laboratory has recently developed a potential solution to this problem. We have patented and validated, a new cell biology platform technology, which allows real-time continuous monitoring of drug, induced optical changes in freshly explanted human tumors. The technology is called Kinetics of Optical Response, or KOR. We believe that, when combined with our knowledge of the hormone and viability factor requirements of cancer cells, the KOR system offers an unprecedented opportunity for evaluating drugs on fresh human tumor explants --- or cell lines and xenographs derived from the explants. The impressive correlation between KOR drug profiling results in vitro and the clinical outcomes in our patient research studies give us confidence that selection of the best available therapy for patients on an individual basis will soon be possibleFor example, a 4-year, multi-institutional study indicated the clinical potential of this technology by establishing a remarkable correlation between KOR chemosensitivity tests on individual9s explanted leukemia cells and the clinical outcome when that patient received treatment. Thus, the KOR results had significant predictive value for both chemotherapy response and survival in patients with acute myelogenous leukemia (AML). In a typical assay, single cell suspensions from normal or abnormal tissues are seeded at a pre-determined density and, following the addition of putative toxic compounds (either alone or in combination at t = 0 or sequentially at later times) plates are placed into the KOR instruments that are programmed for 24 to 72 hours of incubation. By reading OD of each well every 5 minutes OD profiles are generated, which allow a determination of the complete time course of apoptosis and rate of apoptosis which varies as a function of drug dose. Depending on the nature of the curves induced by the added drug or agent, continuous monitoring of any of 4 kinds of responses-- apoptosis, necrosis, proliferation, cytostasis-- is possible, within a single experiment.The KOR technology and has been extensively validated on cell lines and primary tumor explants from cancer patients. Although published results have largely focused on the KOR assay for suspension cultures of hematopoietic cells, we have tested adherent cells with excellent results. For example, in collaboration with a major pharmaceutical company, we screened human colon cancer cell lines with chemotherapeutic agents that were tested in combinations of two or three at a time. These results showed that several combinations of agents were synergistic at several doses. Compared to KOR technology, other current cell biology methods for estimating cell death (apoptosis or necrosis), proliferation, or mitogenesis, are very labor-intensive, produce only indirect and retrospective information and, for the most part, measure a surrogate of death rather than the real time activity itself. Due to the expense and labor required, it is only feasible to use traditional methods (MTT, thymidine uptake, annexin V, DNA fragmentation, etc.) as single endpoint assays. Such assays therefore only provide a snapshot of drug actions at some arbitrary time without providing information regarding when, how often, and with what duration responses are generated. As far as we are aware, no assay other than KOR is easily amenable to continuous monitoring of apoptosis or necrosis.It should also be noted that KOR technology may ultimately permit high throughput screening of drug candidates on freshly explanted cells from virtually any organ. Again, the KOR platform has the potential to significantly impact the manner in which anti-cancer drugs are discovered, tested, achieve FDA approval, and brought into the clinical marketplace. Finally, since our conditions of tumor analysis, expansion and preservation emphasize maintenance of viable cells, the  in vitro  (KOR) stratification offers unique opportunities to sort out the mechanism(s) whereby some patient9s cells respond and other patient9s cells do not-- i.e. the heterogeneity of response. Of perhaps greater importance, fresh patient samples, plus expanded derivatives, can provide an opportunity to test each patient9s cells against virtually all available drugs, alone or in combinations. This could yield life-saving information for some patients with long-term disease. The drugs for such testing can come from at least 4 categories of pharmaceutical agents: 1) FDA approved drugs, regardless of indication; 2) Drugs in clinical trials; 3) Pre-clinical drugs nearing clinical trials and even; 4) early stage agents or hits identified by high throughput screening or designed against specific cellular targets.