Shepherding Therapeutic Cancer Vaccines through Clinical Development | Page 8

www.clinipace.com

When tissue
staging is critical
to the study
design, it’s
important for the
eligibility criteria
to specify that
patients must
either have
previous tissue
samples or be
willing to
undergo a biopsy
prior to
enrollment.

practices (GCPs). If tissue samples are needed, investigators need access to a
well-qualified pathologist. If tumor size will be evaluated, access to a radiology
department is essential for timely and consistent tumor evaluations. Geography
also can be a significant consideration in investigator selection. If tissue samples
for autologous vaccines need to be processed within 48 hours after collection,
airline access and scheduling options will be critical. Sometimes it can be
important to consider the number of ongoing studies a site is involved with; if
there are many studies recruiting the same type of patients, competition can
slow enrollment.

Assays of response. Assays that measure immune responses relevant to

anti-tumor response can help document efficacy. The FDA recommends having
at least two immunological assays to monitor immunologically mediated antitumor response (FDA Guidance, 2009). When the mechanism of action involves
a specific antigen, an assay measuring target antigen expression in tumor tissues
of individual patients can be used in selecting patients and monitoring response.
Specific immune responses to the tumor may be performed using in vitro tests
for antibody or killer T cells. Delayed type hypersensitivity skin testing can be
performed on the patient. However, to date, immunologi