StockWatch: enGene Shares Crater on Declines in Complete Response Rates to Bladder Cancer Therapy

enGene (NASDAQ: ENGN) stock suffered an 83% plunge this past week that reflects just how competitive the field is among drug candidates for nonmuscle invasive bladder cancer (NMIBC)—and how questions over clinical data are enough to send investors scurrying to sell their shares. enGene shares cratered 81% Thursday from $8.85 to $1.72, then fell another 13% Friday, reaching a 52-week low as it finished the week at $1.50. The sharp falloff followed enGene reporting updated data from its Phase II LEGEND trial (NCT04752722) assessing its nonviral gene therapy candidate detalimogene voraplasmid in high-risk, Bacillus Calmette-Guérin (BCG)-unresponsive NMIBC patients with carcinoma in situ (CIS) with or without concomitant papillary disease (CIS±papillary). The data showed a drop in response rates from a November 2025 readout, falling short of company and Wall Street expectations. As of the April 21 data cutoff, 67 of 124 evaluable patients treated with detalimogene (formerly EG-70) achieved a 54% complete response (CR) at any time, a rate that fell to 43% (52 of 121 evaluable patients) CR rate at six months. That compares with the 63% CR at any time and 62% CR rate at six months shown for the first 62 patients assessed, as announced by enGene in November 2025. Also, detalimogene showed a nine-month CR rate of 32.7%, which fell to 13.3% at 12 months after treatment. Engene said it will present its data at the American Urological Association Annual Meeting (AUA 2026), set for May 15–18 in Washington, DC. “While durability outcomes to date are not what we hoped, these data are preliminary,” enGene president and CEO Ron Cooper stressed in a statement. “We are focused on evaluating the totality of the data as it evolves and plan to continue to engage with the FDA and the medical community.” Speaking to analysts, Cooper added: “The data are not yet fully mature, and the durability picture is incomplete. We plan to await longer-term durability data for all of Cohort 1 in the second half of the year and continue our ongoing discussion with the FDA regarding both our statistical analysis plans and plans for potential BLA filing.” At least two analysts warned that the updated data will make it harder for enGene to compete with other developers of NMIBC treatments now in the clinic. “Durability now screens below key benchmarks in the setting, which makes it hard for us to underwrite meaningful commercial upside for detalimogene in what will be a crowded mkt, where ~40% 12‑mo CR is the bar to clear,” cautioned Maury Raycroft, PhD, equity analyst with Jefferies, in a research note. Raycroft slashed enGene’s 12-month price target 82% from $28 to $5. More ominously, Raycroft chopped Jefferies’ peak sales forecasts for detalimogene by 79%—from the $1.7 billion forecasted for the gene therapy across CIS±papillary, papillary‑only, and BCG‑naïve NMIBC, to $350 million for CIS±papillary alone. The NMIBC treatment space has expanded in recent years as established drugs like the cancer immunotherapy blockbuster Keytruda® (pembrolizumab), marketed by Merck & Co. (NYSE: MRK), have been joined on the market by newer therapies. One is Johnson & Johnson (NYSE: JNJ)’s Inlexzo (gemcitabine), an intravesical drug releasing system (iDRS) designed to provide sustained local delivery of a cancer treatment into the bladder. Two other newer therapies are Adstiladrin® (nadofaragene firadenovec-vncg), a nonreplicating adenoviral vector-based gene therapy indicated for high-risk BCG-unresponsive NMIBC with CIS±papillary and marketed by privately held Ferring Pharmaceuticals (which licensed the drug from another private company, FKD Therapies, in 2018); and ImmunityBio (NASDAQ: IBRX)’s interleukin-15 (IL-15) receptor agonist Anktiva® (nogapendekin alfa inbakicept-pmln), indicated with BCG. ImmunityBio is part of the privately held NantWorks portfolio of companies. Those marketed drugs are expected to be joined over the next couple of years by candidates being developed by: - CG Oncology (NASDAQ: CGON), which is expected to report topline data from the Phase III PIVOT-006 trial (NCT06111235) of cretostimogene grenadenorepvec, also called CG0070, as an adjuvant therapy in intermediate-risk NMIBC. First results on the combo of cretostimogene with gemcitabine from the Phase II CORE-008 trial (NCT06567743) are to be presented at AUA 2026. - Relmada Therapeutics (NASDAQ: RLMD), which will present two abstracts focused on its NDV-01, a sustained-release intravesical formulation of gemcitabine and docetaxel being developed to treat NMIBC at AUA 2026. Relmada plans to present nine-month complete response data from its open-label Phase II trial (NCT06663137) assessing NDV-01 in high-risk NMIBC, as well as discuss its open-label Phase III BOOST trial (NCT07313891), which is evaluating NDV-01 vs. surveillance following transurethral resection of bladder tumor (TURBT). Mani Foroohar, MD, senior managing director, genetic medicines, and a senior research analyst with Leerink Partners, noted that enGene’s 54% any time and 43% six-month updated CR rates lagged behind those of three competitors: Anktiva (71% and 56%), cretostimogene (75.5% and 64%), and Inlexzo (82% and 59%). However, he added that Adstiladrin was more comparable to detalimogene, which showed rates of 51% and 41%. “Weaker data in recent patient cohorts and lower-than-expected durability trends undermine our confidence in [detalimogene]’s competitive position and essentially foreclose the possibility of closing the efficacy gap with CGON, JNJ, etc., in a later LEGEND update,” Foroohar wrote in a research note. “With shares trading at a level pricing in program failure, investor focus will center on cohort consistency, data evolution with longer follow-up, and FDA interpretation of the totality of the dataset (questions that will take time to address and will not be resolved prior to full LEGEND data/subsequent regulatory engagement,” Foroohar added. Like Raycroft, Foroohar also now projects $350 million in unadjusted peak year sales for detalimogene, shredding his firm’s projection by 65% from $1 billion. “From here, investor discussion will center on whether longer follow-up and additional cohort maturation can stabilize efficacy trends ahead of further FDA engagement in 2H26.” enGene and Cooper insist that detalimogene is more than up to the challenge of competing with other NMIBC treatments. Of the 52 patients who responded at six months, 37 of 44 patients who had a nine-month assessment were in CR (an additional eight patients are pending evaluation), while 13 of 22 patients who had a 12-month assessment were in CR (an additional 11 patients are pending evaluation). Among patients who showed the 43% six-month CR rate, 14% (6 of 43) successfully converted from non-CR to CR post re-induction. The company cited other data from the LEGEND trial showing that the progression rate to muscle-invasive or advanced disease was 3.2%, a figure enGene calls low. Detalimogene was generally well tolerated, the company added, with 55% of patients having experienced a treatment-related adverse event (TRAE), mostly mild (Grade 1 and 2), though six patients (4.8%) reported a Grade 3 TRAE. “These updated data continue to reinforce the favorable safety and tolerability profile of detalimogene and its clinical activity in a heavily pretreated, high-risk NMIBC patient population with limited therapeutic options,” enGene’s Cooper stated. “Importantly, the low rate of progression to muscle-invasive disease leaves patients eligible for other bladder-sparing therapies.” Detalimogene’s favorable safety profile was also acknowledged by Jefferies’ Raycroft: “We continue to view this administrability/safety profile as a core differentiator vs other intravesical gene/immune constructs (and a key adoption lever), even as durability to date is tracking below expectations.” Odyssey Therapeutics (NASDAQ: ODTX) raised $304 million in gross proceeds through an upsized initial…