BridgeBio’s rare disease drug cleared its first FDA hurdle on July 22. Celldex’s itch drug cleared every hurdle except the one that mattered, on July 21, one day earlier. One is a step closer to patients. The other proved its mechanism worked in a lab sense and got shelved anyway. In between, Tempus AI put $1.5 billion on the table for a cancer-monitoring company it already partly owned.
Tempus AI Buys Personalis for $1.5 Billion to Build Out Its Cancer Monitoring Business
Tempus AI, Inc. (Nasdaq: TEM) signed a definitive merger agreement on July 20 to acquire Personalis, Inc. (Nasdaq: PSNL) for $16.25 per share, a total enterprise value of $1.5 billion net of the stake Tempus already held going into the deal. Personalis shareholders will receive Tempus Class A stock under a floating exchange ratio tied to Tempus’s volume-weighted average share price, capped at 0.3356 shares of Tempus per Personalis share, with Tempus retaining the option to pay up to half the consideration in cash. Tempus already owned roughly 12.5% of Personalis, the product of a 2023 equity investment and a commercial partnership that brought Personalis’s minimal residual disease testing to market under the Tempus banner.
The logic is straightforward even if the deal terms are not. Personalis built its NeXT Personal platform on whole genome sequencing to track minimal residual disease, meaning the trace amounts of cancer DNA that circulate in blood after treatment ends and that can flag a recurrence before it shows up on a scan. Tempus already sells that test to pharmaceutical and biotech customers under the existing partnership. Folding Personalis in directly gives Tempus ownership of the underlying technology instead of a commercial arrangement layered on top of it. The two companies size the total addressable minimal residual disease market at $20 billion.
Merck holds about 13% of Personalis’s voting power and has signed a voting agreement backing the deal. The merger agreement carries a no-shop covenant restricting Personalis from soliciting competing bids, though the board keeps a fiduciary out if a superior proposal shows up, with a termination fee near $76.8 million attached to that scenario. Tempus owes a reverse termination fee of similar size if the deal fails to close by an outside date of April 20, 2027 for reasons within its control. Personalis separately holds the right to walk away if Tempus stock falls below $46 before closing.
The market’s first reaction was not enthusiasm. Tempus shares fell almost 9% the day the deal was announced and Personalis dropped about 12%, an unusual pairing since acquirer and target usually move in opposite directions on takeover news. The business changing hands is growing: Personalis reported preliminary second quarter revenue of $22.4 million on 10,384 clinical tests, a 33% increase in test volume from the prior quarter. Closing is expected in late 2026 or early 2027, contingent on Personalis shareholder approval, antitrust clearance, and Nasdaq listing approval for the new Tempus shares. The deal has not closed as of this writing.
Celldex’s Barzolvolimab Depletes Mast Cells But Fails to Reduce Itch in Prurigo Nodularis
Celldex Therapeutics (Nasdaq: CLDX) reported topline results on July 21 from its Phase 2 study of barzolvolimab in prurigo nodularis, a chronic skin disease that produces hard, intensely itchy nodules. The randomized, placebo-controlled trial enrolled 140 patients across two dosing arms, 150mg and 300mg every four weeks following a 450mg loading dose. Neither arm met the primary endpoint, a four-point or greater improvement on the Worst Itch Numeric Rating Scale at week 12, and the key secondary endpoints missed as well.
What makes this worth more than a line item is that the drug did exactly what it was built to do. Barzolvolimab produced rapid, profound and sustained mast cell depletion, confirmed by significant reductions in serum tryptase, a marker Celldex uses to track mast cell activity in the blood. Mast cells were the hypothesis behind the whole program: deplete them and the itch should follow. It didn’t. Celldex is reading the result as evidence that mast cells are not the primary driver of prurigo nodularis after all, and the company is discontinuing the program in this indication.
The rest of the barzolvolimab pipeline is unaffected by this result. Phase 3 trials in chronic spontaneous urticaria and in cold urticaria and symptomatic dermographism continue, alongside a Phase 2 study in atopic dermatitis. Topline data from the chronic spontaneous urticaria Phase 3 is expected in the fourth quarter. Safety and tolerability in the prurigo nodularis study were described as consistent with prior barzolvolimab trials, including at the new 450mg loading dose, so the miss does not appear to be a safety-driven result. Barzolvolimab is investigational in every remaining indication and has not been approved by the FDA for any use.
BridgeBio’s Encaleret NDA Accepted by FDA for Rare Genetic Disorder ADH1
BridgeBio Pharma (Nasdaq: BBIO) announced July 22 that the FDA accepted its New Drug Application for encaleret in autosomal dominant hypocalcemia type 1, a rare genetic disorder in which the body cannot properly regulate calcium. The FDA assigned a PDUFA target action date of May 8, 2027. The filing is built on the Phase 3 CALIBRATE trial, which BridgeBio says achieved all pre-specified primary and key secondary efficacy endpoints. BridgeBio is already in pre-commercial planning and says it is prepared to launch encaleret on approval, calling it a potential blockbuster opportunity. FDA acceptance for filing does not indicate or guarantee approval, and encaleret remains investigational until a decision is made.
Tempus-Personalis Closing Conditions, Celldex’s Q4 CSU Data, and BridgeBio’s May 2027 PDUFA to Watch
The Tempus-Personalis deal still needs Personalis shareholder approval, antitrust clearance, and SEC registration of the new Tempus shares before it closes, targeted for late 2026 or early 2027. Any regulatory friction would be notable given Tempus’s existing ownership stake and commercial relationship with Personalis, which narrows the antitrust question but does not eliminate it. Celldex’s Phase 3 chronic spontaneous urticaria data due in the fourth quarter is now the read-through for the entire KIT-inhibitor mechanism following the prurigo nodularis miss; a clean result there would support the idea that barzolvolimab works in urticaria specifically rather than mast cell disease broadly. BridgeBio’s May 8, 2027 PDUFA date is more than nine months out, but any advisory committee scheduling or FDA commentary in the interim would be the next marker to watch.
Sources
- Tempus.com: Tempus to Acquire Personalis, Integrating MRD Into AI-Enabled Precision Oncology Platform, July 20, 2026
- SEC EDGAR: Tempus AI, Inc. Form 8-K, Merger Agreement, July 20, 2026
- MobiHealthNews: Tempus AI to Acquire Personalis for $1.5B, July 21, 2026
- Celldex Therapeutics IR / GlobeNewswire via StockTitan: Celldex Reports Results from Phase 2 Study of Barzolvolimab in Prurigo Nodularis, July 21, 2026
- BridgeBio Pharma / GlobeNewswire: BridgeBio Announces FDA Acceptance of NDA for Encaleret for ADH1, July 22, 2026
Editorial Disclosure
This article is based entirely on publicly available information including company press releases, SEC filings, and contemporaneous news coverage. Securities discussed include Tempus AI, Inc. (Nasdaq: TEM), Personalis, Inc. (Nasdaq: PSNL), Celldex Therapeutics, Inc. (Nasdaq: CLDX), and BridgeBio Pharma, Inc. (Nasdaq: BBIO). aktiego.com has not received any compensation from any company mentioned, their management, investor relations representatives, or any third party. No staff member or principal of aktiego.com holds a position in any security mentioned at the time of publication. The Tempus AI acquisition of Personalis was announced July 20, 2026 and has not closed; it remains subject to Personalis shareholder approval, antitrust clearance, SEC registration of new Tempus shares, and other customary closing conditions, with an outside date of April 20, 2027. Tempus AI held an approximate 12.5% ownership stake in Personalis prior to the merger agreement through a prior equity investment and commercial partnership; Merck holds approximately 13% of Personalis voting power and has signed a voting agreement in support of the transaction. Celldex’s Phase 2 study of barzolvolimab in prurigo nodularis was a randomized, placebo-controlled trial enrolling 140 patients; the primary and key secondary endpoints were not met, and Celldex is discontinuing the program in this indication. Barzolvolimab remains investigational in chronic spontaneous urticaria, cold urticaria, symptomatic dermographism, and atopic dermatitis, and has not been approved by the FDA for any indication. BridgeBio’s encaleret is investigational and has not been approved by the FDA; the NDA has been accepted for filing only, which does not indicate or guarantee eventual approval. The PDUFA target action date of May 8, 2027 is a target date, not a guaranteed decision date. No analyst price targets are cited in this article. This coverage is provided for informational and educational purposes only. aktiego.com is not a registered investment advisor. Nothing in this article constitutes financial, investment, or professional advice. These are speculative investments carrying significant risk including potential total loss of capital. Readers are encouraged to conduct their own due diligence and consult a qualified financial advisor before making any investment decisions. For more information please see our full DISCLAIMER.
