Cancer Research Moves Forward by Fits and Starts

I recently returned from the American Association for Cancer Research (AACR) meeting held in Philadelphia. AACR is attended by basic researchers focused on the molecular basis of oncology. Many of the concepts reported will percolate to the clinical literature over the coming years.

There were many themes including the revolution in immunologic therapy that took center stage, as James Allison, PhD, received the Pezcoller Prize for his groundbreaking work in targeting immune checkpoints. The Princess Takamatsu Award given to Dr. Lewis Cantley, recognized his seminal contribution to our understanding of signal transduction at the level of PI3K. A series of very informative lectures were provided on “liquid biopsies” that examine blood, serum and other bodily fluids to characterize the process of carcinogenesis. These technologies have the potential to revolutionize the diagnosis and monitoring of cancers.

The first symposium I attended described the phenomenon of chromothripsis. This represents a catastrophic cellular trauma that results in the simultaneous fragmentation of chromosomal regions, allowing for rejoining of disparate chromosome components, often leading to malignancy and other diseases. I find the concept intriguing, as it reflects the intersection of oncology with evolutionary developmental biology, reminiscent of the outstanding work of Stephen Jay Gould. His theory of punctuated equilibrium, from 1972, challenged many long held beliefs in the study of evolution.

Since the time of Charles Darwin, we believed that evolution was slow and continual.  New attributes were selected under environmental pressure and the population carried those characteristics forward toward higher complexity. Gould and his associate, Niles Eldredge, stated that evolution was anything but gradual. Indeed, according to their hypothesis, evolution occurred as a state of relative stability, followed by brief episodes of disruption. This came to mind as I contemplated the implications of chromothripsis.

Licensed under CC BY-SA 3.0 via Wikimedia Commons

According to the new thinking (chromothripsis and its related fields), cancer may arise as a single cell forced to recover from what would otherwise be catastrophic injury. The reconfiguring of genetic elements scrambled together to avoid apoptosis (programmed cell death) provides an entirely new biology that can progress to full-blown malignancy.

By this reasoning, each patient’s cancer is unique. The results of damage control whereby chromosomal material is rejoined haphazardly would be largely unpredictable. These cancers would have a fingerprint all their own, depending on which chromosome was disrupted.

As high throughput technologies and next generation sequences continue to unravel the complexity of human cancer, we seem to be more and more like those who practice stone rubbing to create facsimiles of reality from the “surface” of our genetic information. Like stone rubbing, practitioners do not create the images, but simply borrow from them.

With each symposium, we learn that cancer biology does not come to be, but is. Grasping the complexity of cancer requires the next level of depth. That level of depth is slowly being recognized by investigators from Harvard University to Vanderbilt as the measurement of humor tumor phenotypes.

Cancer is phenotypic and human biology is phenotypic. Laboratory analyses that allow us to measure, grasp, and manipulate phenotypes are those that will provide the best outcomes for patients. Laboratory analyses like the EVA-PCD.

Poster from Rational Therapeutics Session at 2011 AACR Meeting

As I mentioned in a previous post, on April 3, 2011, I traveled to Florida to present our most recent findings on novel compounds that target two parallel circuits in cancer cells at the American Association of Cancer Research Meeting.

Following are shots of the poster that was presented. I encourage you to leave any comments and/or questions here, as I would be pleased to respond to your inquiries.

American Association of Cancer Research (AACR) Meeting 2011

The Sunday, April 3, 2011, experimental and molecular therapeutics session at the AACR 102nd annual meeting included our presentation on signal transduction inhibitors. Using MEK/ERK and PI3K-MTOR inhibitors we explored the activities, synergies and possible clinical utilities of these novel compounds.

The findings were instructive. First, we saw a good signal for both compounds utilizing the Ex-vivo Analysis of Programmed Cell Death (EVA-PCD) platform. Second, we saw disease-specific activity for both compounds. For the MEK/ERK inhibitor, melanoma appeared to be a favored clinical target. This is highly consistent with our expectation. After all, many melanomas carry mutations in the BRAF gene, and BRAF signals downstream to MEK/ERK. By blocking MEK/ERK, it appeared that we blocked a pathway fundamental to melanoma progression. Indeed, MEK/ERK inhibitors are currently under investigation for melanoma.

For PI3K inhibitors, the highest activity was observed in uterine cancers. This is interest, because uterine carcinomas are often associated with a mutation in the PTEN gene. PTEN is a phosphatase tumor suppressor that functions to block activation of the PI3K pathway. Thus, mutations in the tumor suppressor unleash PI3K signaling, driving tumors to grow and metastasize. Blocking PI3K provided a strong signal, indicating that this approach may be very active in tumors associated with these oncogenic events.

The third point of interest in our report was, perhaps, its most important. Specifically, that we can explore those diseases where MEK-ERK, PI3K and mTOR signaling are less established targets. Cancers of the lung, ovary, colon or breast all manifested profiles of interest. When we combined both pathway inhibitors in a process we call horizontal inhibition, renal cell carcinoma popped up as the best target. These results, though exploratory, suggest a superior approach for drug development, allowing us to identify important leads much faster than the clinical trial process.