Clinical Pharmacology 
Considerations for the 
Development of 
Oligonucleotide 
Therapeutics  
Guidance for Industry 
 
DRAFT GUIDANCE 
 
  This guidance document is being distributed for comment purposes only. 
 
Comments and suggestions regarding this draft document should be submitted within ___ days 
of publication in the Federal Register of the notice announcing the availability of the draft 
guidance.  Submit electronic comments to https://www.regulations.gov.  Submit written 
comments to the Dockets Management Staff (HFA-305), Food and Drug Administration, 5630 
Fishers Lane, Rm. 1061, Rockville, MD  20852.  All comments should be identified with the 
docket number listed in the notice of availability that publishes in the Federal Register. 
 
For questions regarding this draft document, contact (CDER) Office of Clinical Pharmacology 
Guidance and Policy at CDER_OCP_GPT@fda.hhs.gov.  
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Drug Evaluation and Research (CDER) 
 
June 2022 
Clinical Pharmacology 
   
Clinical Pharmacology 
Considerations for the 
Development of 
Oligonucleotide 
Therapeutics  
 
Guidance for Industry 
 
Additional copies are available from: 
Office of Communications, Division of Drug Information  
Center for Drug Evaluation and Research 
Food and Drug Administration 
10001 New Hampshire Ave., Hillandale Bldg., 4th Floor  
Silver Spring, MD 20993-0002  
Phone: 855-543-3784 or 301-796-3400; Fax: 301-431-6353 
Email: druginfo@fda.hhs.gov  
https://www.fda.gov/drugs/guidance-compliance-regulatory-information/guidances-drugs  
 
 
 
 
 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Drug Evaluation and Research (CDER) 
 
June 2022 
 Clinical Pharmacology 
 
  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
TABLE OF CONTENTS 
 
 
 
I.  INTRODUCTION............................................................................................................. 1 
 
II.  CLINICAL PHARMACOLOGY CONSIDERATIONS .............................................. 2 
A.  Characterizing QT Interval Prolongation ................................................................................... 3 
B.  Performing Immunogenicity Risk Assessments .......................................................................... 4 
C.  Characterizing the of the Impact of Organ Impairment ............................................................ 5 
D.  Considerations for Assessing Drug Interactions ......................................................................... 6 
 
 
 
 
 
   
 
  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
1  Clinical Pharmacology Considerations for the Development of 
2  Oligonucleotide Therapeutics  
3  Guidance for Industry1 
4   
5   
6  This draft guidance, when finalized, will represent the current thinking of the Food and Drug 
7  Administration (FDA or Agency) on this topic.  It does not establish any rights for any person and is not 
8  binding on FDA or the public.  You can use an alternative approach if it satisfies the requirements of the 
9  applicable statutes and regulations.  To discuss an alternative approach, contact the FDA staff responsible 
10  for this guidance as listed on the title page.   
11   
12   
13   
14   
15  I.  INTRODUCTION  
16   
17  This guidance provides recommendations to assist industry in the development of 
18  oligonucleotide therapeutics under section 505 of the Federal Food, Drug, and Cosmetic Act (21 
19  U.S.C. 355) and 21 CFR parts 312 and 314.  Specifically, this guidance represents the FDAs 
20  recommendations for certain evaluations including pharmacokinetic, pharmacodynamic, and 
21  safety assessments during oligonucleotide therapeutic development, including:  (1) 
22  characterizing the potential for QTc interval prolongation, (2) performing immunogenicity risk 
23  assessment, (3) characterizing the impact of hepatic and renal impairment, and (4) assessing the 
24  potential for drug-drug interactions.  This guidance provides recommendations on when to 
25  conduct these assessments and what types of assessments are suitable to address these questions.   
26   
27  Oligonucleotide therapeutics are an emerging therapeutic modality with increasing numbers of 
28  drugs in development.2  Antisense and small interfering RNA (siRNA) oligonucleotide 
29  therapeutics have been FDA-approved in recent years to treat rare diseases; in addition, many 
30  oligonucleotide therapeutics are currently in development to treat common chronic diseases.   
31   
32  Oligonucleotide therapeutics include a wide variety of synthetically modified RNA or 
33  RNA/DNA hybrids that are specifically designed to bind to a target RNA sequence to alter RNA 
34  and/or protein expression.  Even within the therapeutic modality, oligonucleotide therapeutics 
35  can differ in several ways, including but not limited to: 
36   
37    Mechanism of action (e.g., splice modulating, RNA interference, RNase H-mediated 
38  cleavage) 
39   
 
1 This guidance has been prepared by the Office of Clinical Pharmacology in the Center for Drug Evaluation and 
Research at the Food and Drug Administration.  
 
2 Rogers H, O Adeniyi, A Ramamoorthy, S Bailey, and M Pacanowski, 2021, Clinical Pharmacology Studies 
Supporting Oligonucleotide Therapy Development: An Assessment of Therapies Approved and in Development 
Between 2012-2018, Clin Transl Sci,14(2):468-475. 
  1  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
40    Structure (e.g., single-stranded RNAs, double-stranded RNAs or RNA/DNA hybrids) 
41   
42    Chemical modifications to the base and/or backbone 
43   
44    Size 
45   
46    Sequence 
47   
48    Delivery strategy (e.g., lipid nanoparticles, liposomes, other polymeric nanoparticles, 
49  polyethylene glycol (PEG), N-acetylgalactosamine (GalNAc)) 
50   
51    Presence or absence of other moieties (e.g., small molecule, proteins, antibodies) 
52   
53  The recommendations in this guidance generally apply to oligonucleotide therapeutics that use 
54  an RNA-centric mechanism of action.  Providing recommendations based on any specific 
55  characteristics (e.g., backbone modification, specific conjugation) is beyond the scope of this 
56  guidance.  This guidance is based on the knowledge gained in the development of 
57  oligonucleotide therapeutics submitted to the Agency in new drug applications (NDA) as of the 
58  date of this guidance.  As the development of oligonucleotide therapeutics evolve (e.g., chemical 
59  modifications to the base and/or backbone, structure, delivery strategy), sponsors should contact 
60  appropriate review Divisions for questions related to the topics in Sections II.A through D of this 
61  guidance.   
62   
63  Oligonucleotide therapeutics that use mechanisms of action such as direct modulation of proteins 
64  (e.g., aptamers) or immunostimulation (e.g., TLR9 agonists) are beyond the scope of this 
65  guidance.  The FDA encourages sponsors to communicate with appropriate review Divisions 
66  during the pre-investigational new drug application (pre-IND) or investigational new drug 
67  application (IND) stage to discuss the development of these therapeutics. 
68   
69  The contents of this document do not have the force and effect of law and are not meant to bind 
70  the public in any way, unless specifically incorporated into a contract.  This document is 
71  intended only to provide clarity to the public regarding existing requirements under the law.  
72  FDA guidance documents, including this guidance, should be viewed only as recommendations, 
73  unless specific regulatory or statutory requirements are cited.  The use of the word should in 
74  Agency guidance means that something is suggested or recommended, but not required. 
75   
76   
77  II.  CLINICAL PHARMACOLOGY CONSIDERATIONS  
78   
79  Oligonucleotide therapeutics generally are cleared rapidly from systemic circulation.  However, 
80  these drugs have longer tissue and pharmacodynamic half-lives.  Therefore, several factors 
81  should be considered in determining which studies are needed to characterize the clinical 
82  pharmacology of these products.   
83   
84  In general, sponsors should characterize the plasma pharmacokinetics of an oligonucleotide 
85  therapeutic following single and multiple doses early in drug development.  However, for some 
  2  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
86  oligonucleotide therapeutics, plasma pharmacokinetics might not reflect the target tissue 
87  distribution, pharmacodynamics, safety, or efficacy.  Therefore, in multiple-dose studies, 
88  sponsors should include an assessment of appropriate pharmacodynamic biomarkers (e.g., target 
89  mRNA, target protein, or a downstream biomarker that reflects modulation of the target protein) 
90  or consider other response measures.  Such assessments are important in situations where 
91  pharmacodynamic changes are independent of plasma pharmacokinetic changes.  The selection 
92  of the pharmacodynamic endpoints should be discussed with the appropriate FDA review staff, 
93  especially in cases where the pharmacodynamic endpoints might not directly reflect target 
94  knockdown (e.g., cerebrospinal fluid for central nervous system targets).   
95   
96  Oligonucleotide therapeutics have certain unique characteristics compared to small molecule or 
97  biological products (e.g., chemistry, structure, sites of action, pharmacokinetic disposition, 
98  pharmacodynamics).  Therefore, sponsors should consult Sections II.A. to II.D. below for 
99  considerations when characterizing QTc interval prolongation, performing immunogenicity risk 
100  assessment, assessing the impact of hepatic and renal impairment, and determining the potential 
101  for drug-drug interactions during oligonucleotide therapeutic development. 
102   
103  Specific considerations should be given to the chemistry (e.g., backbone modification, 
104  conjugation), drug target, plasma protein binding, and route of administration as these factors 
105  determine the distribution of the oligonucleotide therapeutic to the liver, kidneys, and other 
106  tissues as well as determine the exposure (local or systemic) to the drug.   
107   
108  Additionally, appropriate bioanalytical methods should be used to characterize the parent 
109  oligonucleotide and any relevant metabolites, including chain-shortened metabolites.  Refer to 
110  the FDA guidance entitled Bioanalytical Method Validation (May 2018) for additional details.3 
111   
112  A.  Characterizing QTc Interval Prolongation and Proarrhythmic Potential 
113   
114  To date, no large mean effect of oligonucleotide therapeutics on the QTc interval has been 
115  observed in the small number of dedicated QT studies reviewed by the FDA.  However, given 
116  that oligonucleotide therapeutics are a diverse group of drugs (see Section I), available clinical 
117  experience does not adequately support providing an overall conclusion on the proarrhythmic 
118  potential of specific types of oligonucleotide therapeutics (e.g., based on chemistry or delivery 
119  strategies). 
120   
121  An assessment of QT prolongation risk and a proposed QT assessment plan should be submitted 
122  for all oligonucleotide therapeutic development programs as outlined in the FDA guidance 
123  entitled E14 Clinical Evaluation of QT/QTc Interval Prolongation and Proarrhythmic Potential 
124  for Non-Antiarrhythmic Drugs (October 2012) and the E14 Clinical Evaluation of QT/QTc 
125  Interval Prolongation and Proarrhythmic Potential for Non-Antiarrhythmic Drugs Questions 
126  and Answers (R3) (June 2017).  All proposals in the QT assessment plan should be adequately 
127  justified and discussed with the Agency.  The timing and extent of the clinical QT assessment 
128  depend upon the overall benefit/risk profile of the oligonucleotide therapeutic.   
129   
 
3 We update guidances periodically. For the most recent version of a guidance, check the FDA guidance web page 
https://www.fda.gov/regulatory-information/search-fda-guidance-documents 
  3  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
130  B.  Performing Immunogenicity Risk Assessments 
131   
132  An unwanted immune response to an oligonucleotide therapeutic can be generated to the carrier, 
133  backbone, oligonucleotide sequence, or any novel epitopes created from the whole drug (carrier 
134  plus oligonucleotide).  The development of oligonucleotide therapeutics is rapidly evolving, and 
135  new chemistries, modifications etc. can significantly affect the immunogenicity risk and clinical 
136  immunogenicity assessment of a particular product.  
137   
138  The clinical immunogenicity assessment for an oligonucleotide therapeutic should follow a risk-
139  based approach and be included in a product-specific immunogenicity risk assessment as 
140  outlined in the FDA guidance entitled Immunogenicity Assessment for Therapeutic Protein 
141  Products (August 2014).  Some considerations when determining the immunogenicity risk of an 
142  oligonucleotide therapeutic include, but are not limited to:  
143   
144    Product factors:  base sequence, base modification, backbone modification, 
145  strandedness, purity, modified nucleotides, secondary and tertiary structures, and carrier 
146  components (e.g., PEGylated lipid nanoparticles) 
147   
148    Pharmacology of the product:  mechanism of action, cell/tissue target, expression 
149  profile, route of administration, dosing regimen (chronic versus acute) 
150   
151    Patient characteristics:  immune activation status of the population (e.g., auto-immune 
152  or inflammatory conditions), concomitant medications (ability to influence the incidence 
153  or clinical impact of anti-drug antibodies (ADAs) (e.g., immunosuppressants such as 
154  chemotherapy) 
155   
156  The clinical assessment of immunogenicity for oligonucleotide therapeutics usually includes a 
157  multi-tiered immunogenicity assay assessment as outlined in FDA guidance.4  As determined by 
158  the immunogenicity risk assessment, it may be appropriate to develop multiple immunogenicity 
159  assays to measure immune responses to the different components of an oligonucleotide 
160  therapeutic, such as the carrier component (e.g., PEGylated lipid nanoparticles) and/or 
161  oligonucleotides conjugated to protein targeting ligands (e.g., Fab fragments).  In addition, the 
162  mechanism of action of some oligonucleotide therapeutics generates a modified protein (e.g., 
163  splice-altering, exon-skipping oligonucleotide therapeutics); in such cases, the sponsor should 
164  consider an immunogenicity assay measuring antibodies to the modified protein.   
165   
166  Additionally, unwanted innate immune activation should also be measured when appropriate 
167  (e.g., oligonucleotide therapeutic-induced cytokine release, presence of sequences that are known 
168  to be immunogenic in humans such as GU, CpG or 5-P, presence of natural nucleosides with 2-
169  deoxy, 2-OH or unmethylated C).  
170   
171  For clinical immunogenicity assessments, immunogenicity sample collection should coincide 
172  with pharmacokinetic and pharmacodynamic sampling time points to evaluate whether ADAs 
 
4 See the FDA guidance Immunogenicity Testing of Therapeutic Protein Products  Developing and Validating 
Assays for Anti-Drug Antibody Detection (February 2019).  
 
  4  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
173  impact the pharmacokinetics, pharmacodynamics, and any immune-mediated adverse events of 
174  the oligonucleotide therapeutic.  It is also important to evaluate samples to determine if the 
175  oligonucleotide therapeutic interferes with ADA testing.  Of note, as determined by the 
176  immunogenicity risk assessment, it may be adequate to bank samples in early development (e.g., 
177  Phase 1/ First-in-human studies) for later testing if there is new evidence of altered 
178  pharmacokinetics, pharmacodynamics, or immune-mediated adverse events.  Sponsors should 
179  discuss their immunogenicity risk assessment and how it informs their clinical immunogenicity 
180  assessment for a particular product with the Agency. 
181   
182  In certain circumstances, the FDA could also recommend assessing for nucleotide sequence-
183  specific antibodies and/or bioactivity (e.g., neutralization, enhancement).  Any recommendations 
184  for these assays will be informed by clinical concerns, such as oligonucleotide sequence cross-
185  reactivity, novel structures, or modifications and should be discussed with the relevant review 
186  Division on a case-by-case basis.  
187   
188  C.  Characterizing the Impact of Organ Impairment on Pharmacokinetics, 
189  Pharmacodynamics, and Safety   
190   
191  To determine the appropriate approach for characterizing the impact of organ function on the 
192  pharmacokinetics, pharmacodynamics, and safety of the oligonucleotide therapeutic, the sponsor 
193  should identify the role of the liver and kidney in the disposition and elimination of the 
194  oligonucleotide therapeutic by considering in vitro, preclinical, and early Phase 1 clinical data.  
195  These early assessments, along with safety and tolerability information, should be used to inform 
196  the enrollment of subjects with a full range of hepatic and/or renal function in the late-phase 
197  trials.  In addition, in subjects with organ impairment, it is important to consider the impact of 
198  changes in expression and turnover of:  (1) the target of the drug; and (2) in the case of 
199  conjugated oligonucleotide therapeutics, the target of the conjugate that determines the 
200  disposition of the drug to the liver or kidneys (e.g., receptors expressed in liver or kidney that 
201  allow for targeting of the drug to those organs).  
202   
203  When the oligonucleotide therapeutic is not predominantly renally cleared or does not target the 
204  liver, the sponsor should enroll subjects with a full range of renal or hepatic function, 
205  respectively, in late-phase trials based on information from nonclinical studies and early clinical 
206  experience.  The sponsor should provide appropriate justification if subjects with impaired renal 
207  or hepatic function are excluded from late-phase trials.5  
208   
209  When the oligonucleotide therapeutic is substantially renally cleared (i.e., 30 percent or more of 
210  the systemically available drug is excreted unchanged in urine), further characterization of the 
211  impact of renal impairment is recommended.6  In such situations, different strategies can be used 
212  to study the impact of renal impairment on response and drug exposures.  A reduced 
 
5 See the FDA guidance entitled Enhancing the Diversity of Clinical Trial Populations Eligibility Criteria, 
Enrollment Practices, and Trial Designs (November 2020).   
 
6 See the FDA draft guidance entitled Pharmacokinetics in Patients with Impaired Renal Function - Study Design, 
Data Analysis, and Impact on Dosing and Labeling (September 2020).  When final, this guidance will represent the 
Agencys current thinking on this topic.   
 
  5  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
213  pharmacokinetic study design can be considered to assess the impact of severe renal impairment 
214  on the pharmacokinetics, pharmacodynamics, tolerability, and safety of the oligonucleotide 
215  therapeutic.  When applicable, this study should be a multiple-dose study to enable adequate 
216  characterization of pharmacodynamic effects.  The findings from such a study can inform any 
217  additional characterizations as well as the inclusion/exclusion criteria for subsequent late-phase 
218  trials.  With appropriate justification, other alternative approaches can also be considered.7 
219   
220  When the oligonucleotide therapeutic targets the liver, the sponsor can consider alternative 
221  approaches that allow for sequential or adaptive enrollment starting in early phase studies of 
222  tolerability, safety, and pharmacodynamics.8  The sponsor should consider the degree of portal 
223  hypertension and shunting of blood flow around the liver in these studies.  This information can 
224  be used to facilitate the enrollment of subjects with a range of hepatic function in late-phase 
225  clinical trials.  
226   
227  Because changes in organ function can result in pharmacodynamic changes that are independent 
228  of pharmacokinetic changes, whenever appropriate and feasible, the sponsor should conduct 
229  pharmacodynamic assessments.  When appropriate, population pharmacokinetic-
230  pharmacodynamic modeling can help assess the correlation between organ impairment and 
231  pharmacodynamics, other biomarkers, safety, or efficacy data.  Unless there is adequate 
232  justification (e.g., safety concerns), a sufficient number of subjects over a range of organ 
233  function should be enrolled across the drug development program to obtain meaningful data in 
234  all categories of organ function.   
235   
236  D.  Considerations for Assessing Drug Interactions   
237   
238  1.  Pharmacokinetic Interactions with Cytochrome P450 Enzymes and Transporters 
239   
240  a.  Oligonucleotide therapeutics as substrates for cytochrome P450 enzymes and 
241  transporters 
242   
243  Oligonucleotide therapeutics are not typically metabolized by cytochrome P450 (CYP) enzymes.  
244  These drugs are primarily metabolized by endonucleases and exonucleases or are chemically 
245  modified to resist degradation.  Therefore, the disposition of oligonucleotide therapeutics is not 
246  anticipated to be affected by inhibitors or inducers of CYP enzymes.  Additionally, modulation 
247  of efflux transporters such as P-gp and BCRP, hepatic uptake transporters such as OATP1B1 and 
248  OATP1B3, or renal uptake or efflux transporters such as OAT1, OAT3, OCT2, MATE1, and 
249  MATE2/K are generally not anticipated to have a significant impact on the pharmacokinetics of 
 
7 Refer to the FDA draft guidance entitled Pharmacokinetics in Patients with Impaired Renal Function  Study 
Design, Data Analysis, and Impact on Dosing and Labeling (September 2020) for additional information on 
alternative approaches.  When final, this guidance will represent the Agencys current thinking on this topic. 
 
8 For more information on sequential analysis, refer to the concepts mentioned in the following article:  Sahre MD, L 
Milligan, R Madabushi, RA Graham, KS Reynolds, A Terzic, J Benjamin, GJ Burckart, SM Huang, R Schuck, AM 
Thompson, and I Zineh, 2021, Evaluating Patients With Impaired Renal Function During Drug Development: 
Highlights From the 2019 US FDA Pharmaceutical Science and Clinical Pharmacology Advisory Committee 
Meeting, Clin Pharmacol Ther, 110(2):285-288. 
 
  6  Contains Nonbinding Recommendations 
Draft  Not for Implementation 
250  oligonucleotide therapeutics.  If the oligonucleotide therapeutic undergoes substantial renal 
251  active secretion as an unchanged drug, it could be important to evaluate whether an 
252  oligonucleotide is a substrate of renal transporters in vitro.9 
253   
254  b.  Oligonucleotide therapeutics as modulators of CYP enzymes and transporters 
255   
256  Evaluating the drug interaction liability of oligonucleotide therapeutics as inhibitors and inducers 
257  of CYP enzymes or drug transporters usually begins with in vitro assessments.  Refer to the FDA 
258  guidance entitled In Vitro Drug Interaction Studies  Cytochrome P450 Enzyme- and 
259  Transporter-Mediated Drug Interactions (January 2020) for general considerations when 
260  conducting in vitro experiments and interpreting data.  Because differences among the various in 
261  vitro systems have been reported, sponsors should carefully select the appropriate in vitro 
262  systems to evaluate drug interactions.10  Based on current experience, oligonucleotide 
263  therapeutics either do not modulate or minimally modulate the major CYP enzymes and drug 
264  transporters.  However, an overall recommendation for specific types of oligonucleotide 
265  therapeutics (e.g., based on chemistry or delivery strategies) cannot be provided at this time.  The 
266  sponsor should provide adequate justification if in vitro assessments of oligonucleotide 
267  therapeutics as perpetrators in drug-drug interactions are not conducted. 
268   
269  There are other possible mechanisms for interactions between oligonucleotide therapeutics and 
270  CYP enzyme or transporters.  The potential of an oligonucleotide therapeutic to modulate CYP 
271  enzymes or transporters directly (e.g., via off-target hybridization with CYP enzyme or 
272  transporter mRNA transcripts) or indirectly (e.g., by interfering with the synthesis or degradation 
273  of heme or by modulating cytokines) should be evaluated.   
274   
275  If studies indicate that the oligonucleotide therapeutic could modulate CYP enzymes or 
276  transporters, the sponsor should consider clinical studies to evaluate in vivo drug interactions.  
277  For general considerations on study design and conduct, refer to the FDA guidance entitled 
278  Clinical Drug Interaction Studies  Cytochrome P450 Enzyme- and Transporter-Mediated 
279  Drug Interactions Guidance for Industry (January 2020).  
280   
281  2.   Pharmacodynamic Interactions 
282   
283  Oligonucleotide therapeutics can exhibit pharmacodynamic interactions with a concomitant drug 
284  when the pharmacological effect of one drug is altered by that of another drug (e.g., drugs with 
285  shared mechanism of action pathways).  Because such interactions may be unique to individual 
286  therapeutics, the sponsor is encouraged to consult with the relevant review Division regarding 
287  assessment of pharmacodynamic drug interactions.  
 
9 See the FDA guidance entitled In Vitro Drug Interaction Studies Cytochrome P450 Enzyme- and Transporter-
Mediated Drug Interactions (January 2020).  
 
10 Kazmi F, P Yerino, C McCoy, A Parkinson, DB Buckley, and BW Ogilvie, 2018, An Assessment of the In Vitro 
Inhibition of Cytochrome P450 Enzymes, UDP-Glucuronosyltransferases, and Transporters by Phosphodiester- or 
Phosphorothioate-Linked Oligonucleotides, Drug Metab Dispos, 46:1066-74. 
  7