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This industry guidance is the FDA’s first roadmap for nonclinical safety assessments of Oligonucleotide-Based Therapeutics (ONTs) that addresses the diverse properties and actions of ONTs.
Pharmacology Studies
Primary and Secondary Pharmacology
Studies should examine ONTs’ mode of actions, duration and
potential biological effects. Secondary pharmacology studies may be
appropriate for ONTs with mechanisms other than nucleic acid
hybridization (e.g., aptamers).
Safety Pharmacology
Safety evaluations must consider the effects on vital functions, including cardiovascular, respiratory, and central nervous systems, using pharmacologically relevant species. If there are no pharmacologically relevant species, an assessment should still be conducted to assess off-target effects even if hybridization does not occur in the test species.
Assessment of absorption, distribution, metabolism, and excretion (ADME) parameters should be characterized prior to human clinical testing. Whereas existing data may be used for well-characterized
ONT classes.
In vivo and in vitro plasma protein binding assessments are required and should be available prior to human clinical testing.
The prolonged tissue half-life of ONTs can decouple plasma concentrations from Pharmacodynamic (PD) activity. In such cases, incorporating PD biomarkers may guide the dose frequency selection in toxicity studies for a more relevant assessment of drug effects.
General Toxicity Studies
Conducted in two species (one rodent and nonrodent), and at least one should be pharmacologically active, while ensuring that study designs align with ICH M3(R2) (guidance). If the clinical candidate is not pharmacologically active, an appropriate species-specific surrogate can be considered.
ONTs function via nucleotide base pairing or protein binding and thus safety evaluations should address on-target effects, off-target hybridization-dependent effects, and off-target hybridizationindependent effects.
On-Target Effects (Exaggerated Pharmacology)
Assess potential adverse effects resulting from exaggerated pharmacological activity, either through empirical testing or literature-based evaluations.
Off-Target Effects
Hybridization-Dependent: Assess potential binding to non-target RNA or DNA sequences using in silico and in vitro methods.
Hybridization-Independent: Evaluate potential off-target effects involving protein interactions or other cellular components using empirical toxicity assessments.
Genotoxicity Studies
Not necessary for ONTs composed of natural nucleic acids.
ONTs with non-native structures should undergo genotoxicity evaluations.
Reproductive and Developmental Toxicity Studies
Should align with ICH S5(R3) guidelines, with adjustments for ONTs exhibiting prolonged PK/PD effects.
Adjustments to study designs may be necessary for ONTs with unique pharmacokinetics, and the impact of pharmacological activity on DART endpoints can be assessed using appropriate surrogate molecules if the ONT is not pharmacologically active in the standard species.
Carcinogenicity Studies
ICH S1A should be consulted for assessment of the need for carcinogenicity evaluation and ICH S1B for appropriate approaches for testing in rat and mouse (including transgenic mouse (ICH S1B(R1)) for most ONTs, and ICH S1C(R2) and S1B guidelines followed for dose selection.
In certain cases. a 2-year study in a single species may be satisfactory or the use of a weight-of-evidence (WOE), clinical monitoring, plus informed consent for human-specific targets.
Other Toxicity Studies
ONTs must be tested using the same formulation and method intended for human use or data from an unconjugated ONTs when conjugated to a well characterized moiety.
Impurities should be controlled and assessed for safety.
Local tolerance, Immunotoxicity testing should follow ICH and FDA guideline.
