Tagworks Pharmaceuticals Announces Initiation of Third Dose Level in Ongoing Phase 1 Clinical Trial of TGW101 for the Treatment of Solid Tumors

• TGW101 is a next-generation, first-in-class ADC targeting TAG-72 with an MMAE payload, developed based on Tagworks proprietary Click-to-Release linker chemistry; TGW101 is the first bioorthogonal, in vivo click chemistry-activated ADC, which enables superior control of tumor payload activity
• Expect to share preliminary data from the trial by early to mid-2026

NIJMEGEN, Netherlands and BOSTON, Sept. 9, 2025 /PRNewswire/ -- Tagworks Pharmaceuticals BV ("Tagworks"), a clinical-stage precision oncology company using its proprietary Click-to-Release treatment platform to develop a new standard of care for patients suffering from solid tumors, today announced the third dose level has been initiated in the ongoing Phase 1 clinical trial evaluating TGW101, a first-in-class antibody-drug conjugate (ADC) targeting tumor associated glycoprotein 72 (TAG-72) with a monomethyl auristatin E (MMAE) payload, in patients with advanced solid tumors.

"We are pleased to report continued progress in our Phase 1 clinical trial of TGW101 which reflects our strong operational execution and commitment to advancing our pioneering Click-to-Release technology," said Ken Mills, Chief Executive Officer of Tagworks. "The Safety Oversight Committee's decision to proceed to the third dose level highlights TGW101's favorable safety profile to date. We are encouraged by the potential of TGW101's highly differentiated profile to address significant unmet needs in the treatment of advanced solid tumors, while overcoming limitations seen with other ADC therapies. We look forward to sharing preliminary data from the study, including safety, pharmacokinetics, and potential early signs of clinical activity, in early to mid-2026."

The ongoing Phase 1 trial is a multicenter, open-label, dose-escalation study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of TGW101 in patients with relapsed or refractory solid tumors. The primary objectives are to determine the maximum tolerated dose (MTD), recommended Phase 2 dose (RP2D), and dose regimen for cohort expansion.

To date, the trial has initiated three dose levels following favorable safety reviews by the Safety Oversight Committee (SOC). Up to seven dose levels are currently planned, and the maximum dose to be evaluated may be updated based on evolving clinical safety and pharmacokinetic data. The study aims to enroll up to 50 patients across sites in the United States, with potential expansion to additional regions.

Tagworks expects to share preliminary safety and pharmacokinetic data, along with any early signals of efficacy, in early to mid-2026.

About TGW101
TGW101 is an antibody-drug conjugate (ADC) targeting TAG-72, a non-internalizing marker found on the surface of many solid tumor cells. TGW101 consists of a TAG-72-binding diabody conjugated with monomethyl auristatin E (MMAE) toxin. TGW101 is administered intravenous (IV) first and allowed to bind to TAG-72 in the tumor. Then a small molecule trigger is administered IV, resulting in selective chemical cleavage of the linker of the tumor-bound TGW101, release of the MMAE in the extracellular tumor microenvironment and diffusion into surrounding tumor cells. TGW101 is being studied in an open-label, multicenter, Phase 1 dose-escalation clinical trial designed to evaluate safety, tolerability, pharmacokinetics, and preliminary efficacy in patients with advanced solid tumors.

About Tagworks Pharmaceuticals
Tagworks Pharmaceuticals is a clinical-stage precision oncology company using its proprietary Click-to-Release treatment platform to develop a new standard of care for patients suffering from solid tumors by targeting clinically validated tumor markers that so far have remained out of reach of current therapies. Its lead program, TGW101, is an antibody-drug conjugate (ADC) targeting TAG-72, a non-internalizing marker found on the surface of many solid tumor cells. Tagworks is developing a pipeline of novel cancer treatments leveraging its Click-to-Release technology in a range of therapeutics modalities, including ADCs and targeted radiopharmaceutical therapies. The Company is headquartered in the Netherlands with operations in the U.S. For more information, visit us at www.tagworkspharma.com.

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