Merrimack Pharmaceuticals, Inc. MACK is slated to report first-quarter 2016 results on May 2.The company has beaten estimates in three of the last four trailing quarters with an average positive earnings surprise of 6.41%.Let’s see how things are shaping up for this quarter.Factors Influencing This QuarterMerrimack’s first product, Onivyde, gained approval in the U.S. in Oct 2015 in combination with fluorouracil (5-FU) and leucovorin for the treatment of metastatic adenocarcinoma of the pancreas in patients who were previously treated with Eli Lilly and Company’s LLY Gemzar-based therapy. The product, which generated sales of $4.3 million in the first quarter after its approval, is expected to drive the top line even further this quarter.Merrimack’s efforts in commercializing the drug should also boost revenues. The company has been engaged in visiting key institutions, educating physicians, and providing active patient and oncology practice support services.In addition, the National Comprehensive Cancer Network has recently included Onivyde in its Clinical Practice Guidelines in Oncology for pancreatic adenocarcinoma. The new guidelines recognize the product as category 1 second-line therapy for metastatic adenocarcinoma of the pancreas, in patients who were previously treated with Gemzar-based therapy. This further validates the importance of the drug for patients suffering from metastatic pancreatic cancer.Meanwhile, the company is also working on expanding Onivyde’s label to include other indications such as front-line pancreatic cancer, pediatric solid tumors, glioma and metastatic breast cancer. Studies are ongoing in these indications.License and collaboration revenues are expected to drive substantial top-line growth at the company in the to-be-reported quarter.What Our Model IndicatesOur proven model does not conclusively show that Merrimack is likely to beat earnings this quarter. That is because a stock needs to have both a positive Earnings ESP and a Zacks Rank #1 (Strong Buy), #2 (Buy) or #3 (Hold) to likely beat expectations. But that is not the case here as you will see below.Zacks ESP: The Earnings ESP, which represents the difference between the Most Accurate Estimate and the Zacks Consensus Estimate, is 0.00%.Zacks Rank: Although the company’s Zacks Rank #3 enhances the predictive power of the ESP, its 0.00% ESP makes surprise prediction difficult.Note that we caution against stocks with a Zacks Rank #4 or #5 (Sell-rated stocks) going into the earnings announcement, especially when the company is seeing negative estimate revisions.Stocks That Warrant a LookHere are a couple of health care stocks that you may want to consider, as our model shows that they have the right combination of elements to post an earnings beat this quarter.The Earnings ESP for Zoetis Inc. ZTS is +2.44% and it carries a Zacks Rank #3. The company is scheduled to release results on May 4.The Earnings ESP for Agios Pharmaceuticals, Inc. AGIO is +30.44% and it carries a Zacks Rank #3. The company is expected to release first-quarter results on May 5.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report LILLY ELI & CO (LLY): Free Stock Analysis Report AGIOS PHARMACT (AGIO): Free Stock Analysis Report MERRIMACK PHAR (MACK): Free Stock Analysis Report ZOETIS INC (ZTS): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research