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LOS ANGELES, April 23, 2026 (GLOBE NEWSWIRE) -- The Portnoy Law Firm advises ADC Therapeutics S.A., (“ADC" or the "Company") (NYSE: ADCT) investors that the firm has initiated an investigation into possible securities fraud, and may file a class action on behalf of investors.
Investors are encouraged to contact attorney Lesley F. Portnoy, by phone 844-767-8529 or email: lesley@portnoylaw.com, to discuss their legal rights, or join the case via https://portnoylaw.com/adc-therapeutics-sa. The Portnoy Law Firm can provide a complimentary case evaluation and discuss investors’ options for pursuing claims to recover their losses.
ADC’s stock price plummeted $0.65 per share, or 14.13%, to close at $3.95 per share on December 3, 2025, thereby injuring investors. This sharp market contraction was triggered by a December 3, 2025, announcement regarding safety concerns arising from the Company’s clinical development program for a key oncology therapeutic. The primary driver of the valuation collapse was the disclosure of updated data from the LOTIS-7 Phase 1b open-label clinical trial.
The decline was further exacerbated by specific safety signals observed in patients receiving ZYNLONTA® in combination with the bispecific antibody glofitamab (COLUMVI®) for the treatment of relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL). Despite the Company’s characterization of the results in "positive terms," the underlying data revealed that "adverse events occurred in two patients," with one instance identified as being "treatment related." Furthermore, the market reacted negatively to the high frequency of immune-related side effects, as the Company reported that "cytokine release syndrome of all grades was observed in 36.7% of patients across dose levels." The revelation that over one-third of the study population experienced this systemic inflammatory response led to an immediate loss of investor confidence and a rapid erosion of shareholder value as the market adjusted to the heightened safety risks and the potential for a more difficult path toward regulatory approval.
The Portnoy Law Firm represents investors in pursuing claims caused by corporate wrongdoing. The Firm’s founding partner has recovered over $5.5 billion for aggrieved investors. Attorney advertising. Prior results do not guarantee similar outcomes.
Lesley F. Portnoy, Esq.
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