In vitro drug testing using hemopoietic cells: goals and limitations

Area of Science:

• Oncology
• Pharmacology
• Cancer Biology

Background:

• In vitro drug sensitivity assays are explored as predictors of in vivo drug response in cancer.
• Tumor characteristics like stem-cell origin, differentiation, and heterogeneity can influence treatment outcomes, potentially overshadowing simple cytotoxicity.
• Acute non-lymphoblastic leukemia (ANLL) has been a common model, but its drug resistance patterns may not represent other cancers.

Purpose of the Study:

• To evaluate the predictive value of in vitro drug sensitivity for in vivo cancer treatment response.
• To determine the conditions under which in vitro drug sensitivity is a critical determinant of patient outcomes.
• To explore the role of in vitro assays in understanding tumor biology and drug resistance mechanisms.

Main Methods:

• Conducting large-scale clinical trials with well-defined, reproducible in vitro assays and drug exposures.
• Utilizing homogenous patient cohorts with carefully defined response and survival endpoints.
• Analyzing in vitro drug sensitivity as one continuous variable among others influencing in vivo responses.

Main Results:

• In vitro drug sensitivity may predict remissions in some cases, but other biologic variables are often more important.
• For certain rapidly growing tumors, drug resistance emergence related to disease burden might be the key factor.
• The predictive power of in vitro assays varies depending on the tumor type and its specific biologic characteristics.

Conclusions:

• In vitro drug sensitivity assays provide valuable insights into tumor variability and drug response mechanisms.
• Stringent trial criteria, including reproducible assays and homogenous patient groups, are essential for reliable in vitro testing.
• In vitro assays may serve as crucial preclinical drug screens and models for studying drug resistance, potentially becoming obsolete with advances in molecular genetics.