August 2026 Biotech Catalysts: 4 PDUFAs, 2 Ghosts, Ranked

The August 2026 FDA calendar looks packed at first glance. Six PDUFA dates spanning oncology, vaccines, rare disease, and HIV. But when you actually read the details, two of those dates are ghosts: catalysts that have already been consumed or moved. The remaining four split into one genuine small-cap binary event and three mega-cap events where the stock will not move regardless of the outcome. If you are planning August trades around the Q3 FDA calendar, this is what is actually investable.

Price update August 4, 2026 (Polygon, August 3 close): Since this article was published on July 29, the REPL thesis has shifted dramatically. The CTGTAC voted 10-3 in favor on July 30, sending REPL from $5.41 to $11.20 on July 31 (+107%). The August 2 (Sunday) PDUFA has passed with no FDA decision as of August 4 pre-market. REPL closed at $11.91 on August 3 (Polygon), trading $10.13-$12.60 on Monday. The market is pricing in uncertainty about the delayed decision. Two prior CRLs (July 2025, April 2026) keep binary risk elevated. MRNA closed at $55.14 on August 3 (Polygon), up slightly from $54.82 on July 31 — PDUFA tomorrow (August 5). GILD closed at $131.15 on August 3. JAZZ closed at $251.58 on August 3. AZN fell 6.9% to $157.97 on Monday after reported BMY merger talks. See the RP1 PDUFA article for latest updates.

1. Replimune (REPL) | $5.35 | Market Cap $449M | PDUFA August 2 | The Only Real Binary Event

RP1 (vusolimogene oderparepvec) plus nivolumab for advanced melanoma after anti-PD-1 failure. This is the third BLA resubmission. Two prior CRLs: July 2025 and April 2026. The FDA accepted the third resubmission on June 26 with a class 1 review and an August 2 PDUFA date. The RP1 melanoma AdCom met on July 30 to vote on whether the IGNYTE trial results are evaluable and clinically meaningful.

The FDA briefing documents, released July 28, raised broad efficacy concerns. Reuters reported that FDA staff cast doubt on the benefit, questioning whether the study results were “artifactually inflated.” The panel vote is non-binding but a negative recommendation would substantially reduce approval probability. The stock has been crushed: REPL traded at $10.28 on July 20 and closed at $5.35 on July 29, a 48 percent decline in two weeks. Short interest stands at 23.7 million shares, roughly 29 percent of the float.

The clinical data from IGNYTE: ORR of 33.6 percent (95% CI 25.8 to 42.0) in the 140-patient anti-PD-1 refractory cutaneous melanoma cohort, with a 15 percent complete response rate and median duration of response of 24.8 months. Three-year overall survival was 54.8 percent for all treated patients and 83.5 percent for responders. The data is real. The problem is the trial design: single-arm, no randomized control, and the FDA is questioning whether the response rate is evaluable given the absence of a comparator arm. We previously covered the RP1 melanoma PDUFA setup in depth.

At $449 million market cap, this is the only August catalyst where the stock can move 50 percent on the outcome. Approval sends the stock to $15 to $20 on short covering alone. A CRL sends it to $2. The AdCom vote on July 30 is the signal: if the panel voted yes, the stock rips. If the panel voted no, the stock is dead money until August 2 confirms the inevitable CRL.

2. Moderna (MRNA) | $55.81 | Market Cap $22.1B | PDUFA August 5 | First mRNA Flu Vaccine, Low Stock Impact

mRNA-1010 (mFLUSIVA) is the first mRNA-based seasonal influenza vaccine to reach FDA review. The VRBPAC voted 9-0 on June 18, 2026 that benefits outweigh risks for adults 50 and older. The PDUFA is August 5, 2026. If approved, it would be available for the 2026 to 2027 flu season.

The Phase 3 trial enrolled 40,703 adults across 301 sites in 11 countries. mRNA-1010 showed 26.6 percent relative vaccine efficacy versus standard-dose flu shots (2.0 percent versus 2.8 percent influenza incidence). The rVE was consistent across strains: 29.6 percent against A/H1N1, 22.2 percent against A/H3N2, and 29.1 percent against B/Victoria. In the 19,260 participants aged 65 and older, rVE was 27.4 percent. The full Phase 3 results were published in the New England Journal of Medicine.

At $22.1 billion market cap, this approval is immaterial to Moderna’s stock. The flu vaccine market is approximately $7 billion globally. Even if mRNA-1010 captures 10 percent market share, that is $700 million in revenue against Moderna’s $4.5 billion 2025 base. The stock has been trading on COVID franchise erosion and the cancer vaccine platform, not on flu. Approval is likely given the 9-0 AdCom vote, but the stock moves 3 to 5 percent at most. Moderna remains a show-me story on the mRNA platform.

3. Gilead (GILD) | $134.32 | Market Cap $166.8B | PDUFA August 27 | BIC/LEN HIV NDA, Mega-Cap Inmaterial

Bictegravir 75 mg plus lenacapavir 50 mg (BIC/LEN) is a once-daily single-tablet HIV regimen for virologically suppressed adults. The FDA granted Priority Review with an August 27 PDUFA. The NDA is supported by two Phase 3 trials (ARTISTRY-1 and ARTISTRY-2) where BIC/LEN was non-inferior to comparator regimens at Week 48. In ARTISTRY-1, 0.8% of BIC/LEN participants had HIV-1 RNA ≥50 copies/mL versus 1.1% on complex multi-tablet regimens. In ARTISTRY-2, 1.3% versus 1.0% on Biktarvy. No significant safety signals were identified.

Gilead is the HIV franchise leader. Biktarvy generated $14 billion in 2025 revenue. BIC/LEN would be a next-generation option for patients seeking a simpler regimen or those with resistance concerns. But at $166.8 billion market cap, even a $500 million peak sales drug moves the needle by 0.3 percent of revenue. The stock will not react to this approval. We previously analyzed the ISL/LEN weekly HIV program and the lenacapavir PrEP approval. Gilead is a Hold regardless of the BIC/LEN outcome.

4. Jazz Pharmaceuticals (JAZZ) | $256.92 | Market Cap $16.1B | PDUFA August 25 | Ziihera sBLA for First-Line GEA

Ziihera (zanidatamab-hrii) is already approved for previously treated HER2-positive biliary tract cancer under accelerated approval. The August 25 PDUFA is a supplemental BLA for first-line HER2-positive gastroesophageal adenocarcinoma (GEA), a label expansion based on the HERIZON-GEA-01 Phase 3 trial. Both Ziihera plus chemotherapy and Ziihera plus tislelizumab plus chemotherapy demonstrated statistically significant PFS improvements over trastuzumab plus chemotherapy. The Ziihera plus tislelizumab arm also showed statistically significant overall survival improvement. Confirmed ORRs were 70.7 percent and 69.6 percent in the two Ziihera arms versus 65.7 percent in the control arm.

The GEA market is approximately 20 percent HER2-positive of 1 million new cases globally, meaning roughly 200,000 eligible patients. That is a meaningful label expansion from the 12,000-patient BTC population. But Jazz is a $16.1 billion company with $3.8 billion in 2025 revenue. Ziihera’s current BTC revenue is modest. Even with GEA expansion, Ziihera peak sales of $500 million to $800 million by 2029 would add 13 to 21 percent to revenue. The stock moves 3 to 5 percent on approval, not 20 percent.

Ghost Catalyst 1: Merck KEYTRUDA QLEX (Aug 17) | Already Approved July 10

The brief lists an August 17 PDUFA for KEYTRUDA QLEX in combination with Padcev for muscle-invasive bladder cancer. The FDA already approved the Padcev-Keytruda MIBC combination on July 10, 2026, five weeks ahead of the PDUFA date. The catalyst is consumed. MRK at $325.6 billion market cap would not have moved on this approval regardless, but the August 17 date is now a non-event. Do not plan a trade around it.

Ghost Catalyst 2: Savara MOLBREEVI (Aug 22) | PDUFA Moved to November 22

The brief lists an August 22 PDUFA for MOLBREEVI (molgramostim) in autoimmune pulmonary alveolar proteinosis (aPAP). The FDA extended the review period by three months to November 22, 2026, after determining that Savara’s responses to information requests constituted a major amendment to the BLA. The IMPALA-2 Phase 3 trial showed a 6.0 percentage point treatment difference in DLCO change at Week 24 (p<0.001) and an 80.6 meter improvement in 6-minute walk distance at Week 48 (p=0.03). The data is solid. The date just moved. This is a November catalyst now, not an August one.

Risks and Position Sizing

Every pre-PDUFA trade carries CRL risk. The historical CRL base rate is approximately 37 percent. For Replimune specifically, the risk is elevated: two prior CRLs, FDA briefing documents questioning the trial design, and an AdCom where the FDA staff already signaled skepticism. A 2 to 5 percent portfolio allocation per pre-PDUFA play is the maximum prudent size. For the mega-cap catalysts (MRK, GILD, JAZZ), position sizing is irrelevant because the stock will not move enough to matter. For the three-window FDA catalyst trading framework, the entry window for August catalysts is already closing. You are late if you are entering now.

The Verdict: One Trade, Three Watches, Two Ghosts

Ranked by stock-moving potential:

1. Replimune (REPL) | Trade. The only August catalyst where the stock can double or halve. The AdCom vote on July 30 is the key signal. If the panel voted favorably, REPL is a buy into August 2. If the panel voted negatively, stay away. At $449M market cap with 29 percent short interest, the squeeze potential on approval is significant. This is a binary bet on the AdCom outcome, not an investment thesis.

2. Jazz (JAZZ) | Watch. The HERIZON-GEA-01 data is strong and the label expansion is commercially meaningful. But at $16.1B market cap, the stock moves 3 to 5 percent on approval. Not worth a pre-PDUFA position. Buy on approval if the stock dips on a sell-the-news reaction.

3. Moderna (MRNA) | Watch. First mRNA flu vaccine is a milestone for the platform, but the stock is not trading on flu. Approval is likely given the 9-0 VRBPAC vote. The stock reaction will be muted. The real Moderna catalyst remains the cancer vaccine program, not the flu franchise.

4. Gilead (GILD) | Hold. Approval is likely. Stock impact is zero. BIC/LEN is a franchise extension, not a franchise maker. Own Gilead for the HIV pipeline and lenacapavir PrEP, not for this specific PDUFA.

5. Merck (MRK) | Ghost. Already approved. Catalyst consumed. Move on.

6. Savara (SVRA) | Ghost. Moved to November 22. The best biotech stocks ranking already covers SVRA as a November catalyst. Come back in October.

The contrarian call: the market is pricing Replimune for a third CRL after the 48 percent crash. At $449M market cap, the stock is pricing in roughly a 20 percent approval probability. The IGNYTE data shows a 33.6 percent ORR and 24.8 month median duration of response in a population with no standard of care option. If the AdCom voted yes despite FDA staff concerns, the stock has asymmetric upside. That is the only trade in August 2026 that matters.