The 2014 meeting of the American Society of Clinical Oncologists kicked off this weekend with an early battle between AstraZeneca (NASDAQ:AZN) and Clovis Oncology (NASDAQ:CLVS). While much of the excitement at ASCO this year will focus on immunotherapy partnerships as Bristol-Myers Squibb, Merck, and Roche (OTC:RHHBY) try to carve out market share, the data early in the conference has sparked some discussion of non-immunotherapy drug candidates.

AstraZeneca's AZ9291 and Clovis' CO-1686 are both next-generation epidermal growth factor receptor (EGFR) inhibitors. EGFR expression can run rampant in cancer cells, causing them to proliferate uncontrollably. By blocking EGFR, it's possible to cut off the signal responsible for tumor growth.

That was the goal of Roche with its first-generation EGFR inhibitor Tarceva. With FDA approvals for second or third-line treatment in non-small cell lung cancer (NSCLC), first-line treatment in NSCLC patients with a specific EGFR genotype, and first-line treatment in pancreatic cancer, Tarceva has achieved blockbuster status and accounted for 4% of Roche's revenue in 2013. Now, Roche has undertaken what's become the norm and has partnered tumor-targeted therapies with its own immunotherapy candidate MPDL3280A. That should help defend Tarceva's status in what's poised to become a crowded market.

Unfortunately, the rapid proliferation of cancer cells in NSCLC often leads to EGFR-inhibitor resistance, potentially making continued treatment with Tarceva and AstraZeneca drug Iressa less useful. Now, AstraZeneca and Clovis are hoping to overcome that resistance with next-generation EGFR inhibitors. In May, AstraZeneca released Phase 1 data for AZ9291 in patients with advanced NSCLC. In patients that tested positive for the mutation that confers EGFR inhibitor resistance, AZD9291 had a 64% response rate. This weekend at ASCO, Clovis presented comparable numbers from its Phase 1/2 trial of CO-1686, with a 58% ORR.

While efficacy so far may work out to a wash, it's still too early to tell which drug has a better impact on patient survival and safety. Clovis is continuing to lets its trial ride, with median progression free survival (PFS) looking to exceed 12 months. The company is also enrolling patients in larger registrational studies throughout 2014. AstraZeneca's trial already enrolled a larger number of patients which could support early registration under its Breakthrough Designation at the FDA (CO-1686 has been granted FDA Breakthrough Designation as well). In the meantime, AstraZeneca is gearing up for Phase 3 trials.

The numbers could be crucial for the futures of both companies. For Clovis, CO-1686 represents one of two hopeful late-stage candidates aside PARP inhibitor rucaparib. With a market cap of $1.74 billion and $0 in revenue for 2013, CO-1686 will continue to provide critical binary events for investors to watch.

For AstraZeneca, AZD9291 is one of two oncology drugs garnering attention as the company distances itself from a Pfizer takeover bid. The company has to put its money where its mouth is and follow through on CEO Pascal Soriot's promise to shareholders that AstraZeneca would reach $45 billion in annual sales by 2023. AZD9291 approval would be the first step in achieving that lofty goal, and could go a long way in replacing revenue lost when top seller Crestor loses patent protection in 2016.

Final thoughts
Things are looking to really heat up at ASCO this yea, as the reality of a new realm in cancer treatments comes into view. AstraZeneca and Clovis kicked things off with some drama of their own. Don't forget to keep an eye out for late-stage trials and partnership deals for AZD9291 and CO-1686, as those will really determine the future winner in this emerging market battle.