So, Eli Lilly and Co. (LLY) has some good news and some... well, let's call it "regulatory homework" for its new weight loss pill. On Thursday, the company said its oral drug Foundayo (orforglipron) aced a major Phase 3 trial in people with type 2 diabetes and obesity or overweight who are at higher risk for heart problems. The study, called ACHIEVE-4, showed the drug is safe for the cardiovascular system compared to insulin glargine—and actually did a better job at controlling blood sugar and helping patients lose weight. That's the promising part. But then there's the FDA, which has looked at the data and basically said, "Hold on, we need to see more about these potential liver risks."

The ACHIEVE-4 trial was no small affair. It enrolled over 2,700 people across 15 countries, making it the largest and longest study of Foundayo in type 2 diabetes so far. The main goal was to check if the drug could match insulin glargine on heart safety, measured by a combo of bad events like heart attack, stroke, cardiovascular death, and hospitalization for chest pain. Foundayo didn't just match it—it came out looking a bit better, with a 16% lower risk of those events. That met the bar for what's called "non-inferiority," which in plain English means it's at least as safe, if not safer, for the heart.

Where Foundayo really shined, though, was in the efficacy department. Patients on the drug saw bigger drops in A1C levels (that's a key measure of blood sugar over time) and body weight after 52 weeks compared to those on insulin, and those benefits held up through 104 weeks. Even more striking: the trial showed a 57% lower risk of all-cause death for the Foundayo group. That's a pretty big deal, though the company notes it had "nominal statistical significance," which is science-speak for "interesting, but we need to be cautious until we see more data." The drug also improved other heart risk markers like cholesterol and blood pressure.

On the safety front, Foundayo's profile lined up with what you'd expect from the GLP-1 class of drugs—think drugs like Ozempic. About 10.6% of patients stopped taking it due to side effects during the minimum 52-week treatment period, and a deep dive into liver safety didn't raise any red flags for drug-induced liver injury. So far, so good.

But here's where it gets tricky. The FDA has been reviewing things and sent Lilly a letter saying, essentially, "We see some signals here that worry us." The agency is concerned about potential liver injury and exposure during breastfeeding, and it's not convinced that observational studies will cut it—they want actual clinical trials to nail down the risks. There's also a note about "retained gastric contents," which could increase the chance of lung issues if someone needs surgery, so the FDA wants a study using ultrasound to see how fasting and stopping the drug affects stomach emptying. In other words, Lilly has some extra tests to run before this pill can get the green light.

Despite that, Lilly is pushing ahead. The company says it plans to submit Foundayo for approval in type 2 diabetes to the FDA by the end of the second quarter, using a fast-track voucher to speed things up. As for the stock, Eli Lilly shares were up 0.77% at $912 in premarket trading on Thursday, according to market data. So, investors seem cautiously optimistic, but they're probably keeping an eye on that FDA to-do list.