Biotech on April 14, 2026: Replimune Collapses as Lilly Buys ADCs

Two stories set the tone for biotech

Two stories from the middle of April 2026 sum up the biotech market at that point. One came from the regulator and the other from the buyers. On Monday, April 13, investors had their first full trading session to react to the Food and Drug Administration's second rejection of Replimune's melanoma therapy, and they wiped out most of the company's remaining market value. The next morning, Eli Lilly announced it would buy CrossBridge Bio, a Houston startup working on next-generation antibody-drug conjugates (ADCs). Seen together, the two events describe the sector's split of that period. Small developers faced harsh, binary regulatory risk, while large drugmakers kept paying for early-stage science.

There was also a market-structure change aimed at the traders who drive small-cap biotech. On April 14, the SEC approved FINRA's proposal to scrap the pattern day trading rule, including its $25,000 minimum equity requirement and the related account restrictions.5 How that affects volatility in catalyst-driven stocks is still unknown. Even so, it removed a long-standing limit on retail accounts that trade biotech news.

Replimune: what a second rejection cost

Replimune got its second complete response letter on April 10, 2026, the same date set as the deadline for its resubmitted application for RP1 combined with nivolumab in advanced melanoma.4445 The company pointed to a 34% response rate and a median response duration of 24.8 months in the 140-patient IGNYTE cohort. It said that without timely accelerated approval, RP1 was not viable, and that it would cut jobs and substantially scale back U.S. manufacturing.42

The stock fell in two steps. Shares dropped about 19% to $4.76 on April 10. Then, on April 13, they lost another 64.29% to $1.70, according to figures repeated in later class-action notices.4346 Intraday reporting from that Monday showed a steeper move, with the stock opening near $1.71 and quoted at a $1.57 close.47 That gap probably reflects when each figure was captured. Either way, the scale of the loss is not in doubt. Cantor Fitzgerald and Piper Sandler both cut the stock to Neutral, and Piper set a $4 price target.47

The company's complaint was about process as much as data. Replimune said the FDA had assigned a new review team to the resubmission, that this team never met with the company, and that a senior member of the original team had said publicly that clinical reviewers found the evidence adequate but leadership disagreed.4245 The FDA's objections, as later summarized, were about whether a single-arm trial could isolate RP1's contribution alongside nivolumab. The agency also cited a varied patient population and uncertainty in how responses were assessed.14

What happened next makes the April selloff look less like a final verdict on the drug and more like a price on regulatory uncertainty. By May, Replimune had reached an agreement with the FDA to resubmit, and the stock jumped nearly 80% on the news.45 An advisory panel voted ten to three in RP1's favor in late July.14 The therapy was eventually granted accelerated approval and is now listed as Tudriqev.5018 Shareholders who sold at the April low lost money on a drug that later reached the market. Investors are now pursuing a securities class action over the period leading up to the April letter.46

Timing at the agency matters to this reading. The April letter was issued while Vinay Prasad led the Center for Biologics Evaluation and Research. His tenure drew criticism from industry and rare-disease advocates over how he treated single-arm evidence, and support from those who wanted stricter standards. He left at the end of April 2026.14 In March, Reuters had already noted that a rare gene therapy approval came under Prasad despite his stated doubts about surrogate endpoints.19 The fairest conclusion is that FDA decisions in spring 2026 were hard to predict, and markets priced that in harshly.

Lilly's CrossBridge deal: small price, clear signal

Lilly's April 14 purchase of CrossBridge Bio was small by its recent standards: up to $300 million in cash, made up of an undisclosed upfront payment plus a development milestone.5152 Coverage agrees on what Lilly is buying. CrossBridge's lead candidate, CBB-120, targets TROP2 and carries two payloads, a topoisomerase I inhibitor and an ATR inhibitor. The company argues this pairing could widen the range of safe and effective doses compared with approved TROP2 ADCs such as Gilead's Trodelvy and AstraZeneca and Daiichi Sankyo's Datroway.5256 Most outlets describe the asset as preclinical, with an application to start human trials expected in 2026.5159 One local report said the lead drug was already in early clinical trials, which conflicts with the rest of the coverage and the company's own description.57

Outlets counted Lilly's deal pace differently. FirstWord called CrossBridge Lilly's fourth acquisition of 2026, after Ventyx, Orna and Centessa, and its first in oncology.56 Fierce, citing PitchBook, said Lilly had bought 16 biotechs since 2023.52 There was also a small disagreement over when Lilly bought the ADC startups Emergence Therapeutics and Mablink Bioscience. BioPharma Dive dated those deals to 2023 and Fierce to 2024.5152

The bigger point is that CrossBridge started a run of deals. Within two weeks, Lilly agreed to buy Kelonia Therapeutics, which works on in vivo CAR-T therapy, for up to $7 billion, and Ajax Therapeutics, a JAK2 inhibitor developer, for up to $2.3 billion.2122 By October, one tracker counted Lilly at 13 acquisitions for the year.25 The CrossBridge deal also follows Lilly's plan for a $5 billion Virginia facility partly dedicated to ADC production, so the company is building manufacturing capacity alongside its pipeline.5658

The ADC rush and an active April for deals

CrossBridge did not stand alone. A week earlier, Gilead agreed to buy the German ADC developer Tubulis for $3.15 billion upfront and up to $1.85 billion in milestones.2722 BioPharma Dive noted that more than 20 ADCs are now approved and many are moving into earlier lines of treatment. That explains why large companies are paying for the next technical step, such as dual payloads, rather than copying first-generation designs.51

April as a whole was one of the busiest deal months of the year. One tracker logged 11 biotech acquisitions in the month. These included Neurocrine's $2.9 billion purchase of Soleno, UCB's deal for Neurona worth up to $1.15 billion, and Chiesi's roughly $1.9 billion takeover of KalVista.25 The month peaked with Sun Pharma's $11.75 billion agreement for Organon on April 26, which multiple outlets called the largest biopharma deal of the year at that point.2223 Gilead completed its roughly $7.8 billion Arcellx purchase on April 28.21 Days later, BioSpace reported that Gilead was eliminating most of Arcellx's workforce, a reminder that these deals often bring layoffs.28

The obesity backdrop

Lilly's spending had strong commercial support behind it. On April 1, the FDA approved Foundayo (orforglipron), Lilly's oral GLP-1 pill for weight management. It was the first new molecular entity approved under the Commissioner's National Priority Voucher pilot, and reports called it the fastest such approval since 2002.3738 One patient-facing guide dated the approval April 2, while most coverage says April 1.3931 Shipping through LillyDirect began April 6.38 On April 16, two days after the CrossBridge announcement, Lilly said its ACHIEVE-4 trial had reaffirmed the drug's cardiovascular and overall safety profile.31

That contrast frames the analysis. The same FDA that cleared a blockbuster-scale oral drug in about 50 days also rejected a small company's breakthrough-designated therapy after reassigning its review team.3842 Large, randomized programs with uncontested endpoints moved quickly. Single-arm datasets from small companies were exposed to shifts in agency leadership.

What it means

The events of mid-April point to a two-speed market. Biotechs with their own regulatory catalysts carried unpredictable risk, and Replimune's 64% one-day drop shows how harshly that risk was priced.43 Large acquirers, meanwhile, treated early-stage platforms like CrossBridge's as cheap options, paying a few hundred million dollars for preclinical assets that could challenge established drugs.55

The main lesson from Replimune's later approval is that April's prices reflected FDA unpredictability more than the drug's science.50 For investors, the most dependable source of returns that spring came from takeovers rather than drug approvals. For the agency, Prasad's departure soon after made the April rejection look more like a product of that period's leadership than a permanent standard.14