Operationalizing ADC Clinical Trials: Dose, Safety, and Design

Antibody–drug conjugates (ADCs) are rapidly reshaping the oncology treatment landscape. By combining the targeting precision of monoclonal antibodies with the cytotoxic potency of small-molecule payloads, ADCs offer the promise of improved efficacy with more controlled toxicity. This potential has fueled unprecedented growth across the pipeline, with dozens of ADCs already approved and hundreds more in development globally.ⁱ

Yet, while the science behind ADCs continues to advance, translating these therapies into successful clinical programs presents a distinct set of operational challenges. ADC trials demand heightened safety oversight, specialized site capabilities, innovative dose-finding strategies, and a renewed focus on patient-centric trial design. Addressing these challenges early creates a stronger foundation for efficient, patient-centric development.

The Current ADC Landscape

The pace of ADC development has accelerated dramatically over the past decade. Advances in linker chemistry, payload selection, and antibody engineering have expanded the therapeutic window and improved tolerability compared with earlier generations of ADCs. Modern ADCs are increasingly designed with site-specific conjugation, fully humanized antibodies, and more stable linkers, all of which contribute to improved safety profiles.

Despite these advances, ADCs remain inherently complex therapies. Narrow therapeutic windows, payload-dependent toxicities, and tumor heterogeneity place increased demands on trial design, safety oversight, and site execution—making operational planning a critical determinant of program success.

Site Selection: Matching Capabilities to Trial Phase

One of the earliest—and most consequential—operational decisions in ADC development is selecting sites with the right capabilities for each phase. Early-phase studies, in particular, require sites with deep experience in oncology drug development and the infrastructure to support intensive safety monitoring. Academic centers with specialized oncology units, advanced pharmacy capabilities, and experience managing complex adverse events are often best suited for first-in-human and dose-escalation studies.

As ADC programs progress into later phases and safety profiles become better characterized, sponsors can consider expanding into community oncology settings to broaden patient access and support enrollment goals. However, this transition must be carefully managed. Community sites may require additional training, resources, and operational support to safely administer ADCs and recognize nuanced toxicity signals early.

Across all phases, critical site capabilities include:

• Familiarity with ADC-specific safety profiles and mechanisms of action
• Infrastructure for extended monitoring windows and complex pharmacokinetic (PK) sampling
• Emergency preparedness for managing infusion reactions and acute toxicities
• Specialized pharmacy and drug handling capabilities

Balancing specialized expertise with geographic diversity is essential to support both patient safety and representative enrollment.

Site Preparedness and ADC-Specific Training

Even when sites are well selected, consistent execution depends on targeted preparation and training tailored to ADC complexity. Protocol-specific education should address toxicity recognition and management, PK sampling procedures, and detailed sample handling and shipping requirements. Given the complexity of ADC trials, consistency in execution across global sites is critical to data quality and patient safety.

Beyond investigator and staff training, patient education tools play an important role in operational success. ADC-specific informed consent materials, patient wallet cards, caregiver resources, and clear safety guidelines help patients understand their treatment and recognize symptoms that warrant immediate medical attention. Empowering patients and caregivers improves safety reporting and can reduce downstream complications.

Dose Optimization in the Era of Project Optimus

Dose optimization has become one of the most operationally complex aspects of ADC development, with implications for design, site burden, and regulatory alignment.  Historically, oncology trials prioritized identifying the maximum tolerated dose (MTD). However, regulatory initiatives such as Project Optimus emphasize the importance of identifying the optimal biologic dose (OBD): the lowest dose that achieves meaningful clinical activity with acceptable safety.

This shift has significant operational implications. Modern dose-finding approaches increasingly rely on Bayesian adaptive designs, continual reassessment methods, and model-informed drug development. These designs often include multiple dose-expansion cohorts to better characterize exposure–response relationships across patient subgroups.

While scientifically robust, these approaches introduce practical challenges. Sponsors must balance the need for rigorous safety data with pressure to advance programs efficiently. Identifying sites experienced with complex trial designs and aligning dose-optimization strategies with regulatory expectations are essential to maintaining momentum without compromising data integrity.

Biomarker-Driven Enrollment: Operational Realities

As ADC programs increasingly rely on biomarker-defined populations, operational feasibility can directly influence enrollment success. In some cases, ADC targets are not included in standard diagnostic panels, leading to high screen-failure rates and extended enrollment timelines.

To address these challenges, sponsors should implement proactive pre-screening pipelines. This includes working closely with sites to identify eligible patients early, establishing clear biospecimen collection and shipping workflows, and determining whether central or local laboratory testing is most appropriate. Real-time tracking of pre-screening activity helps teams adjust strategies quickly and avoid bottlenecks.

Ensuring site readiness is equally important. Sites must have experience handling biospecimens, access to cold storage and shipping infrastructure, and systems to track patients who consent for screening separately from treatment. Partnerships with community molecular testing providers can further expand access and reduce barriers to participation.

Reducing Patient Burden Through Thoughtful Design

Patient burden is not just a design consideration—it is an operational variable that can shape enrollment, retention, and data quality. ADC trials can be demanding for patients, often requiring long monitoring windows, frequent clinic visits, overnight stays, and invasive procedures for PK sampling.

Sponsors are increasingly adopting strategies to reduce burden while preserving data quality. Phased PK approaches limit intensive sampling to early cycles, while home nursing visits, electronic patient-reported outcomes (ePROs), and remote monitoring technologies reduce the need for frequent site visits. Concierge support services can help patients navigate logistics such as travel and scheduling, further easing participation.

Importantly, incorporating the patient voice early in protocol development can reveal opportunities to simplify procedures without compromising scientific objectives. Collaborating with patient advocacy groups, convening advisory boards, and seeking feedback on informed consent materials help ensure protocols are both feasible and patient-centric.

Looking Ahead: The Future of ADC Development

The ADC field continues to evolve rapidly. Next-generation ADCs featuring dual payloads, bispecific antibodies, immune-stimulating conjugates, and novel linker chemistries are already entering clinical development. Combination strategies pairing ADCs with checkpoint inhibitors, targeted therapies, or chemotherapy are expanding therapeutic potential while adding new layers of operational complexity.ⁱⁱ

Emerging applications of artificial intelligence offer promising tools for optimizing ADC development. AI-driven compound design, digital twin modeling for tumors, and biomarker prevalence prediction may enhance patient selection and streamline trial planning. As these innovations mature, operational strategies will need to evolve alongside the science.

What It Takes to Execute ADC Clinical Trials Successfully

Successful ADC clinical trials require more than scientific innovation. They demand operational strategies that account for safety, dose optimization, site readiness, and patient experience at every stage of development. Early investment in site readiness, operational planning, and cross-functional collaboration can mitigate risk, improve data quality, and accelerate timelines.

As ADC pipelines continue to grow, sponsors who prioritize operational excellence will be best equipped to translate complex therapies into meaningful outcomes for patients.

Learn how thoughtful operational planning can support safer, more efficient ADC clinical trials. Contact us to discuss your program today.

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REFERENCES:

[i] DCAT Value Chain Insights. (2025, May 29). Antibody drug conjugates: Will the growth prospects continue or not—or is the shine off? https://www.dcatvci.org/features/antibody-drug-conjugates-will-the-growth-prospects-continue-or-not-or-is-the-shine-off/

[ii] Buyukgolcigezli, I., Tenekeci, A. K., & Sahin, I. H. (2025). Opportunities and challenges in antibody–drug conjugates for cancer therapy: A new era for cancer treatment. Cancers, 17(6), 958. https://doi.org/10.3390/cancers17060958