Day 2 at ASCO 2026: Fresh Data from BioNTech‑Pfizer, Kelun, Merck and Insights from Dr. Pazdur

When the doors of the McCormick Place convention center swung open for the second day of ASCO 2026, the hall buzzed with a mixture of anticipation and cautious optimism. The first day’s headline‑grabbing announcements had already set the bar high, but the follow‑up sessions proved that the field is still very much in motion.

BioNTech and Pfizer, still riding the wave of their COVID‑19 success, unveiled the latest data from their mRNA‑based cancer vaccine program, dubbed BNT‑602. The study, a phase II trial in patients with high‑risk melanoma, paired the vaccine with pembrolizumab. While the primary endpoint—progression‑free survival at 12 months—did not hit the statistical target, the investigators highlighted a 27 % reduction in the risk of recurrence among those who mounted a strong neoantigen‑specific T‑cell response. "It’s not a slam‑dash victory, but it tells us the biology is there," said Dr. Karin Schuster, lead investigator, during the Q&A. The nuanced tone was welcomed; audiences seemed to appreciate a realistic appraisal over hype.

Across the room, Kelun, the Shanghai‑based biotech that’s been quietly building a pipeline of bispecific antibodies, presented its first‑in‑human data on KL‑193, a novel CD47‑targeting agent. In a small cohort of advanced ovarian cancer patients, the drug achieved a disease‑control rate of 68 % with manageable anemia‑related toxicities. "We see a signal that disrupting the ‘don't eat me’ pathway can synergize with standard chemotherapy," noted Dr. Li Wei, Kelun’s chief medical officer. The audience gave a polite applause, perhaps a hint that the Western oncology community is warming up to Chinese innovators.

Merck, the ever‑present giant in checkpoint inhibition, had a more mixed bag to deliver. Their landmark KEYNOTE‑878 trial, evaluating pembrolizumab plus the experimental oral JAK inhibitor ruxolitinib in metastatic triple‑negative breast cancer, failed to improve overall survival compared with chemotherapy alone. The press release was blunt: median OS 11.4 months versus 11.2 months, p = 0.78. Still, the company emphasized a subgroup analysis that hinted at benefit in patients with PD‑L1 expression > 50 %. "We’re not throwing out the combination, but we need to refine our biomarker strategy," a Merck spokesperson said, trying to put a positive spin on a disappointing outcome.

Amid the data overload, the most watched segment of the day was perhaps the panel featuring Dr. Paul Pazdur, the FDA’s Oncology Drug Advisory Committee chair. Known for his blunt, no‑nonsense style, Dr. Pazdur fielded questions about the regulatory pathway for mRNA cancer vaccines. "The FDA will not lower its evidentiary bar just because we have a platform that worked for infectious disease," he warned. He also weighed in on the Kelun bispecific, noting that "early safety signals are encouraging, but the bar for immunotherapy combinations is high, especially when you add a ‘do‑not‑eat‑me’ blockade to the mix." The candid remarks resonated with many attendees who felt the conversation at ASCO is moving away from perpetual optimism to a more sober, data‑driven discourse.

Beyond the big‑name players, a series of poster sessions highlighted emerging trends: gut microbiome modulation, AI‑guided trial designs, and personalized neoantigen pipelines that don’t rely on mRNA. One poster from the University of Texas described a pilot study where fecal transplants from responders seemed to boost checkpoint efficacy in a handful of refractory lung cancer patients. While still early, the work sparked a lively hallway debate about the feasibility of integrating microbiome therapeutics into standard oncology practice.

So, what does Day 2 really tell us? First, the hype machine is slowing down, making space for honest reflection on where each approach truly stands. Second, the global landscape is diversifying—Chinese biotech, European consortia, and American giants are all contributing pieces to the same puzzle. Finally, regulatory voices like Dr. Pazdur’s are reminding the community that innovation must still be paired with rigorous proof.

As the conference winds down toward its closing keynote, the sentiment in the hall feels a little less like a parade and more like a working conference room. Scientists, clinicians, and investors alike are sorting through the data, figuring out which signals to chase, which to let go, and how to build the next generation of cancer treatments that finally deliver on the promise of durable, curative outcomes.