Stemcentrx Charges Out of Stealth: Science Does All the Talking

09.25.2015 : -

Earlier this month, ARTIS Ventures-backed Stemcentrx charged out of stealth mode with a boom heard across the industry. This small, private South San Francisco biotech company revealed an impressive five investigational drugs in human clinical trials generating positive responses in patients with small cell lung cancer, triple-negative breast cancer, ovarian cancer, and peritoneal cancer. Stemcentrx has two additional drugs beginning Phase I clinical trials, and is growing its pipeline of novel targets addressing additional major cancer types.

Early Phase I/II trial results from the company’s lead program are already being hailed as one of the most exciting breakthroughs in small-cell lung cancer in four decades. Lead Investigator M. Catherine Pietanza, M.D. at Memorial Sloan Kettering Cancer Center noted, “The activity of the drug that we have seen is remarkable, and importantly, the durable, long-term responses are notable in such an aggressive disease where progression is normally very rapid.”

Since our decision to lead the first institutional financing round nearly six years ago, it has been our privilege to work shoulder-to-shoulder with Stemcentrx founders Scott Dylla, Dan Reiner, and Brian Slingerland. They have fully embraced the cancer stem cell (CSC) paradigm to discover curative therapeutics for cancer patients. The CSC paradigm proposes the existence of a cellular hierarchy in solid tumors, where a small sub-population of cells at the top of the hierarchy, known as tumor initiating cells or CSCs that drive tumor growth as they self-renew and promote perpetual cell division.

These cancer “seeds” are believed to represent a small percentage of the total population of cells within a tumor (<1-2%), whereas progenitor and non-tumorigenic cell (NTG) byproducts of CSCs can represent greater than 99% of tumor volume, but are incapable of initiating new tumors and fueling perpetual growth. It’s not a surprise that data show CSCs are resistant to standard oncology therapies such as chemotherapy and radiation. This helps explain why after initial shrinkage or a reduction of growth rate, tumors most often recur as CSC tumors that benefit from reduced competition for nutrition from the reduction of the bulk NTG cells that were selectively killed by the therapy. Together with the Stemcentrx team, we believe and have maintained that current cancer drugs (antibodies and small molecules) are limited in significantly impacting tumors because their targets are not expressed on CSCs, and therefore do not impact the activity of CSCs. We also believe current cancer therapies suffer from a narrow therapeutic window, which is the measure of the therapy’s ability to shrink or slow tumor growth progression relative to deleterious side effects. Chemotherapy and radiation have proven to be effective de-bulking therapies, but have significant side effects due to poor specificity between the tumor cells and normal tissue. As dosing and effect is increased, so too are the side effects. Most important, the positive effects on tumor growth are usually only temporary, as tumors often mutate, re-grow at accelerated rates, and metastasize subsequent to treatment.

Stemcentrx believes that to cure patients with solid tumors, the next generation of cancer therapies must target and eliminate tumor-perpetuating CSCs.

Since the company’s founding in 2008, Scott, Dan, and Brian have relentlessly and precisely executed against their vision. They have also developed a world-class platform to accurately identify, isolate, and analyze the characteristics of CSC. In turn, this has enabled them to develop an enviable pipeline of drugs that work to target and eliminate those cells and/or their ability to direct tumor proliferation. It has been both a historic and remarkable journey, and we couldn’t be more proud of what this truly talented team has accomplished.

Those less familiar with Stemcentrx and the success of its drug discovery platform will marvel at how a relatively young and unknown company could become so valuable. However, we have long felt that we are in the midst of a technological renaissance within the area of health and wellness driven by multiple tail winds, such as the mapping of the human genome and the DNA of all living systems, the growing adoption of targeted therapeutics and immunotherapies, the digitization of healthcare and the move towards more transparent organic health-conscious diets.

The value created for those who invest wisely within health and its impact on lives can be more than we ever imagined. This belief gave us the confidence to invest in Stemcentrx at a time when the largest and most successful venture funds were afraid to venture into healthcare and biotechnology.

The unveiling of Stemcentrx this month proves in real-time that there is indeed an opportunity to create trillions of dollars in value for those who have the foresight, fortitude, and belief to fund game-changers that are also life-changers. Stemcentrx symbolizes the true spirit of deep science, venture investing, and the rich history of innovation from Silicon Valley.

— Stuart Peterson, General Partner, first institutional investor and outside Board Member of Stemcentrx