Sub Heading

Date

ICH M7 – Regulatory Updates & Industry Practices

ICH M7 Indian Roadshows 2020February 28, 2020

March 02, 2020

Muzaffar Khan, Ph.DMuzaffar.khan@lauruslabs.com

Introduction

2

• Updates to ICH M7 (R2)• Common structural alerts involved in chemical synthesis• Misattributed structural alerts• Aryl-boronic acids & esters• Acyl/sulfonyl chlorides• Sulfonate esters• Nitrosamines• Regulatory deficiencies • ICH M7 best practices

ICH M7 R2

3

• The M7(R2) Expert Working Group (EWG) is developing AI limits / PDEs for new mutagenic impurities and revising AI for impurities already listed in the Addendum.Potential impurities in drug substances: Compound-specific toxicology limits for 20 synthetic reagents and by-products, and a class-specific toxicology limit for alkyl bromides. Regul. Toxicol. Pharmacol. 94 (2018), pp. 172–182.

• Adapt the classification of anti-HIV therapeutics to medicines for lifelong treatment.

• Elaborate and bring clarity on estimated (theoretical) purge factor for clearance of mutagenic impurity.

• Update the M7 text and develop a Question & Answer document to clarify and address Quality and Safety issues and concerns.

Additional compound specific limits

4

Mutagenicity, genotoxicity and cancer

5

Indirect mechanisms of genotoxicity; M Kirsch-Volders et al. Tox. Letters 140/141 (2003) 63/74

Mutagenicity, genotoxicity and cancer

6

• Mutagens are agents that bind directly with DNA and cause inheritable changes to DNA base pair sequence.

• Genotoxicity – Damage to genetic material (DNA and chromosomes).• Genotoxicants that are non-mutagenic typically have threshold

mechanisms and usually do not pose carcinogenic risk in humans at the level ordinarily present as impurities.

• There is growing evidence of thresholds in mutagenicity (MMS, EMS etc.). For such impurities, compound specific AI/PDE can be justified based on TD50/BMDL10 & NOAEL from the in vivo cancer studies.

• Not all mutations lead to cancer.• Oncogenes & tumour suppressor genes play important role in cancer.• Mitigation factors - ADME, detoxification, DNA repair, apoptosis/

autophagy/anoikis to remove damaged cells.• Non-mutagenic carcinogens are outside the scope of ICH M7.

Structural Alerts (Mueller; PhRMA white paper)

7

Common structural alerts for mutagenicity

8

Common structural alerts involved in chemical synthesis

1. Alkyl sulfonate esters2. Alkyl halides3. Alkyl hydrazines4. Alkyl aldehydes5. Alkyl N-nitrosamines6. Aryl boronic acids7. Aromatic amines & aromatic Azo groups8. Aromatic N-oxides9. Aziridines10.Carboxylic/Sulfonic acid halides11.Carbamates12.Dialkylsulfates13.Epoxides14.Michael acceptors15.Nitro groups

Common structural alerts for mutagenicity

9

Common structural alerts involved in chemical synthesis

1. Alkyl sulfonate esters2. Alkyl halides3. Alkyl hydrazines4. Alkyl aldehydes5. Alkyl N-nitrosamines6. Aryl boronic acids7. Aromatic amines & aromatic Azo groups8. Aromatic N-oxides9. Aziridines10.Carboxylic/Sulfonic acid halides11.Carbamates12.Dialkylsulfates13.Epoxides14.Michael acceptors15.Nitro groups

Misattributed Structural Alerts

10

1. Alkyl and aryl sulfonic acids or sulfonate anions; only alkyl/aryl sulfonate esters are alerting

2. Aromatic aldehydes; only formaldehyde & some di-aldehydes are alerting; formaldehyde is not carcinogenic through oral route

3. Amines in general; only aromatic amines are alerting4. Aromatic halides and tertiary alkyl halides – only primary and secondary alkyl

halides are alerting; chain length and modifications impact the mutagenic potential of alkyl halides

5. Mesityl oxide and diacetone alcohol6. Carbamates; only vinyl carbamate/ethyl carbamate (excluded from Derek alerts)

(Williams et al.)7. Michael Acceptors (soft electrophiles)8. N-Oxides in general; Only 'certain' aromatic N-oxides (e.g. must have > 1 aromatic

ring) (Myatt et al.)9. Carboxylic/Sulfonic acid halides (Derek Alert 315; Equivocal); Acid chlorides react

with DMSO to form mutagenic chlorodimethylsulfide (CDMS) 10. N-Methylols (Derek Alert 307; Equivocal) – Genotoxic through hydrolytic formation

of formaldehyde (LaVoie EJ, Benigni & Bossa)

Mutagenicity of Aryl-boronic acids and esters

11

• Aryl-boronic acids and esters are commonly used synthetic intermediates in pharmaceuticals.

• General practice is to control Aryl-boronic acids and esters at TTC levels.

• Derek Alert – 746: Arylboronic acid or derivative.

• Ames assay: 12 out of 13 compounds tested were mutagenic. DNA adducts were not isolated in 32P-postlabelling studies carried out on two mutagenic compounds. Boronic acids represent “novel class of bacterial mutagen” that may not act by direct covalent binding to DNA. [O'Donovan et al., 2011].

• Many of the active compounds in this class only produce weak positive results in the Ames test, with and without metabolic activation, most commonly with Salmonella typhimurium TA100 and TA1537 and Escherichia coli WP2 uvrA strains.

• There is currently no experimental evidence to show that arylboronic acids form adducts with DNA.

Mutagenicity of Aryl-boronic acids and esters

12

• Pellizzaro et al. demonstrated that there are electronic and steric factors related to the bacterial mutagenicity of arylboronic compounds, which can be measured via the 11B NMR chemical shift with 86% accuracy for prediction.

• Hansen et al. tested 44 arylboronic compounds in bacterial reverse mutation assay to understand the SAR and proposed oxygen mediated oxidation of boron compounds to generate organic radicals as a potential mechanism for mutagenicity.

• In another study four benzoxaboroles and one boronic acid ester produced negative results in the Ames assay, chromosomal aberration and in vivo micronucleus study (rat bone marrow). One of these compounds was not carcinogenic in the 2 year mouse and rat bioassay (Ciaravino et al.).

• Eight Aryl boronic acid/ester scaffolds mutagenic in Ames test were non-mutagenic in follow-up in vivo studies (Masuda et al.).

Aryl-boronic acids & esters– In vivo data

13

Structure & Chemical name CAS No. In vitro Mutagenicity Results In vivo study results

3,5- Difluorophenylboronic acid (DFPBA)

156545-07-2Positive (Ames, MLA, comet, MN)(Callan 2013)

Non mutagenic in Pig-a, Micronucleus, and Comet Results

Phenylboronic acid (PBA)

98-80-6 Positive (Ames)(Hansen et al. 2015)

Non mutagenic in Pig-a, Micronucleus, and Comet Results

3-Quinoline boronic acid (QBA)

191162-39-7Positive (Ames)(Lhasa Vitic database)

Non mutagenic in Pig-a, Micronucleus, and Comet Results

Imidodicarbonic acid, 2-[6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-pyrazinyl]-, 1,3-bis(1,1-dimethylethyl) ester (IDCPBE)

1400668-06-5Positive (Ames)(Gilead Sciences) Non mutagenic in Pig-a

In Vivo Mutagenicity Testing of Arylboronic Acids and Esters (Masuda et al.)

Aryl-boronic acids & esters– In vivo data contd.

14

Structure & Chemical name CAS No. In vitro Mutagenicity Results In vivo study results

Pyrimidinyl boronic acid (PyBA)

109299-78-7Positive (Ames) (Lhasa Vitic database)

Non mutagenic in Pig-a, Micronucleus, and Comet Results

4-methyoxyphenylboronic acid (MPBA)

5720-07-0

Positive (Ames, MLA) (Callan2013) Negative (comet, MN) (Callan 2013)

Non mutagenic in Pig-a, Micronucleus, and Comet Results

Thiomorpholine, 4-[[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]methyl]-,1,1-Dioxide (TTDPMD)

1092563-25-1 Not available Non mutagenic in Pig-aand Comet Results

Boronic acid, [4-[(1,1- dioxido-4-thiomorpholinyl)methyl]p henyl]- (BADTMP)

747413-23-6 Not available Non mutagenic in Pig-aand Comet Results

B

O H

O H

N

N

B

O H

OH

O

O

BO S

O

O

N

S

O

O

N

B

OH

O H

In Vivo Mutagenicity Testing of Arylboronic Acids and Esters (Masuda et al.)

Mutagenicity of Acyl/sulfonyl chlorides

15

• Acyl/sulfonyl halides are often used in chemical synthesis as reactive intermediates.

• Acyl/sulfonyl halides are known to react with DMSO to form alkyl halides via the well established Pummerer rearrangement.

• Acyl chlorides react with DMSO to yield the corresponding carboxylic acids and chlorodimethylsulfide (CDMS) which is a known mutagen.

• Sulfonic acid chlorides can also react with DMSO to form CDMS.

Mutagenicity of Acyl/sulfonyl chlorides

16

• The impact of solvent on bacterial mutagenicity of acyl/sulfonyl chlorides was studied in detail by Amberg et al.

• Ames data of 39 acyl/sulfonyl chlorides was generated in MeCN, DMSO and other solvents by GSK and Sanofi.

• Most of these were Ames +ve in DMSO and Ames -ve in other solvents.• Methane sulfonyl chloride (MsCl) was Ames +ve in DMSO, MeCN, Acetone

& MeOH.• MsCl is prone to react with each of these solvents and form known or

potentially mutagenic intermediates (CDMS with DMSO, isopropenylsulfonate with acetone, MMS with methanol, methyl sulfonyl nitrilium with MeCN).

• Ames data of acyl/sulfonyl chlorides should be handled with care.• Because of the solvent interactions the Ames test cannot measure the

mutagenic potential of this class in most cases. A purge argument may be easier than trying to make this assessment.

Regulatory deficiency - Thionyl chloride

17

“You classified thionyl chloride used in the preparation of 2,6-Dimethyl phenoxy acetyl chloride as ICHM7 Class 5 compound, this is not acceptable, since it is potential mutagenic compound (Ames positive). Please amend your discussion and demonstrate that it is controlled in line with ICHM7” (WHO Query).

Thionyl chloride Ames data from ToxnetCCRIS (TOXNET): Ames positive[SHORT-TERM TEST PROGRAM SPONSORED BY THE DIVISION OF CANCER BIOLOGY, NATIONAL CANCER INSTITUTE, MS. ELLEN ZAIKA, ASSISTANT PROJECT OFFICER , p. Y84]

Thionyl chloride- Derek Nexus

18

Derek Nexus PredictionMutagenicity in vitro in bacterium is EQUIVOCAL Alert matched: 315 Acid halide

This alert describes the activity of carboxylic acid halides, carbamoyl halides, thionyl halides and sulphonyl halides in the Ames test, as illustrated by toxicophores (I), (II) and (III). Testing has generally been restricted to acid chlorides, where positive results are generally observed only when DMSO is used as a solvent, conditions which produce questionable results for these compounds [Amberg et al.]. For example, 15/18 compounds that gave positive results under these conditions produced negative results when using solvents other than DMSO, e.g. thionyl chloride and phenacetyl chloride [Amberg et al]. Only 2 compounds were considered to be unambiguous mutagens in this study: dimethylcarbamic chloride, which displayed activity in Salmonella typhimurium TA98 and TA100, and 2-fluorobenzoyl chloride [Amberg et al].

Thionyl chloride- Sarah Nexus

19

Sarah Nexus PredictionFor the Mutagenicity in vitro endpoint with the Sarah Model - 2.0 model, the compound is predicted to be - Negative with 100% confidence in the prediction

Thionyl chloride was Ames +ve in DMSO whereas Ames -ve in MeCN (Amberg A)

ICH M7 specifically uses thionyl chloride as an example for Option 4 Control strategy; due to its inherent reactivity it readily hydrolysis to SO2 and HCl.

Data Source Source Activity Call

(1) Amberg A, Harvey JS, Czich A, Spirkl HP, Robinson S, White A, Elder DP, Organic Process Research and Development, 2015, 19, 1495-1506

Negative

(1) Bayer AG Report, 1988, 16766, 1-(2) Seifried HE, Seifried RM, Clarke JJ, Junghans TB, San RHC, Chemical Research in Toxicology, 2006, 19, 627-644

Positive

(1) ISSTOX Website: http://www.iss.it/meca/index.php?lang=1&anno=2013&tipo=25

Positive

(1) A collection of Ames test data derived from the FDA/CFSAN/OFAS knowledge base

Positive

Sulfonate esters - formation

20

• The mechanism of alkyl sulfonate formation was first predicted in 2006 by Snodin and confirmed experimentally in 2009 by Teasdale et al.

• The esterification reaction proceeds in two steps :1. Protonation of the alcohol to form an oxonium ion and release of a

mesilate anion. 2. Extremely slow nucleophilic displacement of the hydroxonium moiety by

the mesilate anion, to produce alkyl mesilate and water.

Sulfonate esters - formation

21

Key factors involved in generation of an alkyl sulfonate from a sulfonic acid and an alcoholic solvent (Snodin)

1. Acid strength of reaction medium;2. Reaction temperature and contact time;3. Presence or absence of water in the reaction medium;4. Mechanism: nucleophilic displacement of hydroxonium ion from

protonated alcohol by sulfonate anion;5. Reaction rate: extremely slow owing to feeble nucleophilicity of sulfonate

anion.

Sulfonate esters in sulfonic acid salts

22

AlkOH + RSO2OH H2O + RSO2OAlkBase

Hypothetical side reaction

X

Key: Alk = methyl, ethyl or isopropyl; R = methyl, phenyl or p-tolyl

Sulfonate esters – Process controls & limits

23

Process controls for avoiding sulfonate ester formation • Avoidance of excess acid (using no more than 0.995 molar equivalents)• Optimizing mixing conditions to avoid high local sulfonic acid concentrations• Slow addition of sulfonic acid• Initial charging of the reactor with only 90% molar equivalents of sulfonic acid

and utilizing the final 10% with monitoring of pH• Including water in salt formation and isolation steps• Introduction of a base significantly retards formation of a sulfonate ester• Avoidance of reactions at elevated temperatures

Leverage compound specific AI limits for sulfonate estersMMS: 31.8 μg/day [TD50 of 31.8 mg/kg/day in rats; CPBD]EMS: 104 μg/day based on NOAEL from transgenic-mouse 28-day toxicity study (Mueller & Gocke)IprMS: 25 μg/day based on NOAEL from Rat Pig-a assay (Coffing et al.)

Regulatory deficiencies on sulfonate esters

24

“Please demonstrate that the p-toluene sulfonic methyl ester that may be formed from p-toluene sulfonic acid used in the in-house synthesis of 4-(pyridine-2-yl) benzaldehyde and from sodium methoxide used in the same step, is controlled in line with ICHM7 as a potential genotoxic impurity”. (WHO query)

“The genotoxic impurity Ethylmethansulphonate can be formed in the last step of the synthesis of the starting material due to reaction of solvent ethanol and mesyl group eliminated in the epoxide formation reaction. Please provide a discussion of the control of this impurity in line with ICH M7”. (WHO query)

“Your limit ‘NMT 132.5ppm’ for MMS and ‘NMT 433ppm’ for EMS is not accepted by MFDS. So, please revise the limit as per TTC limit of 1.5µg/day for life time exposure. And even if not detected in API, since it is genotoxic impurity, you have to control either in intermediate specification as every test OR in API specification as periodic test”. (MFDS – Korea query)

ICH M7 (Note 5) allows compound specific acceptable intakes for mutagenic impurities with known carcinogenic potency.

Regulatory deficiencies on sulfonate esters

25

“You established a compound specific limit of NMT 318 ppm for impurity methyl methane sulfonate based on a TD50 of 31.80 mg/(kg/day) for carcinogenicity. However, the limit proposed is not considered acceptable, since in line with ICHM7 (R1) on p.32: ̔…other considerations (besides the carcinogenic risk), such as quality standards, may affect final product specifications.̕ Hence the TTC based limit of NMT 15ppm should be adopted for the impurity.” (WHO query)

The proposed limit of 318 ppm for MMS is well within the identification threshold of 0.10% per ICH Q3A (MDD of DS is 100 mg/day).

Compound specific limits can be allowed as long as they do not exceed ICH Q3 limits.

Compound specific limits – Regulatory deficiency

26

“It is noted that the molecule 1-(2-methyl-5-nitrophenyl) guanidine nitrate shares the same alerting moiety with 2-methyl-5- nitroaniline. However, 1-(2-methyl-5-nitrophenyl) guanidine nitrate and 2-methyl-5- nitroaniline are not the same compounds. In addition, the acceptable limit for the impurity 2-methyl-5- nitroaniline is derived from TD50 of 2-methyl-5- nitroaniline, and you have not provided document to show that the two impurities have the same or similar TD50 values. Therefore, your justification for the impurity 1-(2-methyl-5-nitrophenyl) guanidine nitrate is not acceptable.” (USFDA deficiency)

TD50 of 2-methyl-5-nitroaniline is 277 mg/kg/day in rats which equates to AI of 277 µg/day.

Other regulatory deficiencies on MIs

27

“The proposed limit for isopropyl chloride is not considered acceptable. You are requested to revise the limit to 2.5 ppm in accordance with the TTC limit”. (HC query challenging a 10x default limit)A ten times default limit can be applied for mono-functional alkyl chlorides.

“We have noted that sodium nitrite is used in the manufacture of Adenine by some suppliers. Sodium nitrite that is carried over could potentially react with other secondary and tertiary amines downstream to generate nitrosamines. Therefore, please update your starting material specification for adenine to include a test for residual nitrite with a limit of “Not Detected”, and to include a statement that Adenine should only be sourced from suppliers that do not use sodium nitrite in their manufacturing process”. (HSA-Singapore)Avoidance is not a flawed principle to control nitrosamines!

Other regulatory deficiencies on MIs

28

“After technical consultation about your response to deficiency #2 in the amendment dated 4/4/2017, the Agency does not agree with you on that treatment with imatinib mesylate unlikely extends beyond 10 years of treatment. The Reference Listed Drug label indicates that treatment with imatinib mesylate tablet can extend beyond 10 years to lifetime…” (USFDA query)ICH M7 Note 7 allows AI of 10µg/day for mutagenic impurities in non-genotoxic anticancer treatment being used in a patient population with longer term survival (breast cancer, chronic myelogenous leukemia).

“The control approach option 4 according to ICHM7 chosen for dimethyl sulfate is acceptable. However, according to the discussion provided in your response, dimethyl sulfate rapidly converts into monomethyl sulfate in the presence of methanol. Monomethyl sulfate itself is considered as a potential genotoxic impurity and has to be controlled in line with ICH M7 below the level of 1.25ppm in the API”. (WHO query)Monomethyl sulfate is not mutagenic! (John P. Guzowski, Jr.)

Mutagenic impurities in genotoxic APIs

29

“You have not provided a discussion on the assessment on the potential of mutagenic impurities with structural alerts (i.e., epoxides, nitrogen mustards, alkyl group, aryl group, nitro compounds, halogen groups, anhydrides, etc.) and may have a mutagenic potential. As such, you are requested to provide a complete assessment and if necessary, propose appropriate control of all potential impurities with mutagenic potential as per ICHM7”. (HC query)

“Your response to Comment 1 of the Deficiency Letter (DL) issued November 09, 2017 is not acceptable. The response does not discuss the assessment of the reagents used in the drug substance manufacturing process for structure alerts indicative of possible genotoxicity. It is acknowledged that the API is a known genotoxic compound, which would allow reagents that possess related structure to the API to be excluded from further assessment. However assessment should be performed on reagents with unrelated structure alerts. The review of the reagents used in the drug substance manufacturing process suggests that reagent Trimethylsiliyl Trifluoromethane sulfonate (TMS-Triflate) includes a possible structure alert for genotoxicity”. (HC query)

Mutagenic impurities can be controlled at acceptable levels for non-mutagenic impurities in APIs that themselves are genotoxic.

Nitrosamines

30

• Nitrosamines are probable, high potent human carcinogens falling under “Cohort of concern”.

• Nitrosamines are formed by the reaction of secondary amines with nitrosylcation (generated in-situ from sodium nitrite under acidic condition).

• Chloramine can react with secondary amines which upon aerial oxidation can yield nitrosamines, e.g. NDMA in drinking water.(T. Karanfil et al.)

NHCl2 + HN NNH

Cl O2 NNO

Nitrosamines – Regulations

31

• EMA/248364/2019 Rev. 1 - Sartan medicines: companies to review manufacturing processes to avoid presence of nitrosamine impurities (April 17, 2019; Article 31, review of sartans) first in July 2018.

• EMA/189634/2019 - Information on nitrosamines for marketing authorisation holders (September 19, 2019)

• EMA/CHMP/428592/2019 Rev. 2 - Questions and answers on “Information on nitrosamines for marketing authorisation holders (December 20, 2019)

• EMA/511347/2019 - EMA advises companies on steps to take to avoid nitrosamines in human medicines (September 26, 2019)

• Information regarding nitrosamines controls/methods published by USFDA, WHO, Health Canada, Swissmedic, HSA-Singapore.

• NDMA detected in non-sartans such as Ranitidine, Metformin etc.

Nitrosamines – Regulations

32

• European Pharmacopoeia 10.0 Monographs of all sartans have been revised to set strict interim limits for NDMA and NDEA

Nitrosamines

33

• Sodium nitrite used to quench azides used in generation of tetrazole ring in sartans.• DMF used in the same step can hydrolyse in acidic conditions to dimethylamine

which is also a known impurity of DMF.• Diethylamine present as an impurity in TEA lead to the formation of NDEA.• NMBA in losartan, is likely to have been generated via formation of N-methyl-4-

aminobutyric acid from hydrolysis of N-methyl-2-pyrrolidinone (NMP) and subsequent reaction with nitrite.

• A comprehensive risk assessment is necessary to evaluate the potential for nitrosamine contamination in drug substances.

• Nitrosamines formed earlier in a synthesis are more likely to be purged through factors such as reactivity, solubility, etc. than those formed at a late stage in the synthesis (Teasdale A.). No detectable levels of NDMA or NDEA were reported in candesartan, losartan, or olmesartan by the CHMP.

• Nitrosamines can be formed only if secondary amines and nitrite are present simultaneously and under specific reaction conditions.

• Using pure reagents (free from secondary amines) can minimize risk of nitrosamines formation.

Nitrosamines – Potential sources

34

Potential nitrosamines in drug substances

35

Nitrosamines – limits in pharmaceuticals

36

• After the transition period, companies must exclude the presence of even lower levels of NDEA or NDMA in their products (< 0.03 ppm).

• The 30 ppb limit (LOQ) is set based the OMCL network data.• Methods for determination of NDMA and NDEA in sartans developed by the Official

Medicines Control Laboratories are available for reference on EDQM website. • There is a very low risk that nitrosamine impurities at the levels previously found in

some sartan medicines could cause cancer in humans. • The additional cancer risk from exposure to nitrosamines at their interim limits for a

life-time would be very low when compared with the life-time risk of cancer in the EU (1 in 2).

• Long-term limits of nitrosamines for non-sartan products are still under consideration.

Nitrosamines – USFDA’s General Advice

37

USFDA’s General Advice on nitrosamines in ARBs

FDA has determined that the measure of N-Nitrosamine content is now subject to a reporting threshold of 0.03 ppm. When reporting N-Nitrosamine content, DP and API manufacturers must demonstrate that the method used to measure N-Nitrosamine content is appropriately developed and validated, fit for purpose, and should be capable of achieving a sensitivity by the Limit of Quantitation below or equal to the reporting threshold. ….In addition, APIs and DPs are subject to a limit on the total number of N-Nitrosamine compounds which may exceed the reporting threshold; this limit is NMT 1. If more than one N-nitrosamine impurity is found above the reporting threshold in a drug product, the manufacturer should contact the Agency for evaluation if they wish to distribute that product.

Nitrosamines – Your responsibilities

38

• Evaluate the possibility that nitrosamines are present in every concerned medicine within 6 months;

• prioritize evaluations starting with medicines more likely to be at risk of containing nitrosamines;

• take into account findings from CHMP’s review of sartans;• notify authorities of outcome of risk evaluations;• test products at risk of containing any nitrosamines;• immediately report detection of nitrosamines to authorities;• apply for necessary changes to marketing authorizations to address

nitrosamine risk;• complete all of these steps within 2 years (HC & Swissmedic) and 3 years

(EMA), prioritizing high-risk products.

Watch out for other nitrosamines that can potentially form from secondary amine intermediates/impurities.

Implementation of ICH M7 - best practices

39

• Understand the scope of ICH M7.• Differentiate between true alerts/PMIs and misattributed alerts.• Conclude an in silico assessment with an expert opinion (Myatt et al.)• Investigate the in vivo relevance of in vitro mutagens if necessary (Note 3).• Perform risk assessment for potential MIs.• Differentiate between “unrealistic” and potential MIs based on a scientific

rationale. Avoid discussion on MIs that are unlikely to be formed (and are not detected) to avoid unwarranted queries.

• Propose appropriate control strategies for MIs (Option 1, 2, 3 or 4).• Use theoretical purge factors (with experimental data if necessary) to

support Option 3 & 4 control strategies.• Apply compound specific and class specific limits (ICH M7 Note 5) and Less

Than Life-time approach (ICH M7 Note 7) where applicable; it makes a big difference in the overall efforts/resources!

References

40

1. Bercu J.P. (2018) Potential impurities in drug substances: Compound-specific toxicology limits for 20 synthetic reagents and by-products, and a class-specific toxicology limit for alkyl bromides. https://doi.org/10.1016/j.yrtph.2018.02.001.

2. Mueller L. (2006) A rationale for determining, testing, and controlling specific impurities in pharmaceuticals that possess potential for genotoxicity. http://dx.doi.org/10.1016/j.yrtph.2005.12.001.

3. Williams R.V. et al. (2017) Carbamates and ICH M7 classification: Making use of expert knowledge -http://dx.doi.org/10.1016/j.yrtph.2017.03.025

4. Glenn J. Myatt et al. (2018) Extending (Q)SARs to incorporate proprietary knowledge for regulatory purposes: is aromatic N-oxide a structural alert for predicting DNA reactive mutagenicity? https://doi.org/10.1093/mutage/gey020

5. LaVoie EJ, Briggs G, Bedenko V and Hoffmann D. (1982) Mutagenicity of substituted carbazoles in Salmonella typhimurium., http://dx.doi.org/10.1016/0165-1218(82)90004-0.

6. Benigni, R., Bossa, C., (2011) Mechanisms of chemical carcinogenicity and mutagenicity: a review with implications for predictive toxicology. https://doi.org/10.1021/cr100222q

7. O’Donovan and Mee (2010) Boronic acids – a novel class of bacterial mutagen. http://dx.doi.org/10.1093/mutage/geq090O’Donovan et al (2011) Boronic acids—A novel class of bacterial mutagen. http://dx.doi.org/10.1016/j.mrgentox.2011.05.006

8. Pellizzaro et al. (2015) Investigating a Relationship between the Mutagenicity of Arylboronic Acids and 11B NMR Chemical Shifts. http://dx.doi.org/10.1021/acs.chemrestox.5b00078

9. Hansen et al. (2015) Boronic Acids and Derivatives—Probing the Structure–Activity Relationships for Mutagenicity. http://dx.doi.org/10.1021/acs.oprd.5b00150

10. Ciaravino et al. (2013) An assessment of the genetic toxicology of novel boron-containing therapeutic agents. http://dx.doi.org/10.1002/em.21779.

11. Masuda Herrera MJ (2019) In Vivo Mutagenicity Testing of Arylboronic Acids and Esters http://dx.doi.org/10.1002/em.22320.

12. Pummerer rearrangement March,J. Ed. Advanced Organic Chemistry, 4th Edition, Wiley Intersience, New York, 1992, pp. 1236.

References

41

13. Amberg A. (2015) Do carboxylic/sulfonic acid halides really present a mutagenic and carcinogenic risk as impurities in final drug products? https://dx.doi.org/10.1021/acs.oprd.5b00106.

14. Snodin D. (2006) Residues of genotoxic alkyl mesylates in mesylate salt drug substances: Real or imaginary problems? https://doi.org/10.1016/j.yrtph.2006.02.003

15. Teasdale A. et al. (2009) Mechanism and Processing Parameters Affecting the Formation of Methyl Methanesulfonate from Methanol and Methanesulfonic Acid: An Illustrative Example for Sulfonate Ester Impurity Formation. https://doi.org/10.1021/op800192a.

16. Snodin D.J. (2019) Elusive impurities – evidence versus hypothesis. Technical and regulatory update on alkyl sulfonates in sulfonic-acid salts, https://doi.org/10.1021/acs.oprd.8b00397.

17. Mueller L., Gocke E. (2009) Considerations regarding a permitted daily exposure calculation for ethyl methanesulfonate. https://doi.org/10.1016/j.toxlet.2009.03.015.

18. Coffing, S. L. (2014) Evaluation of the In Vivo Mutagenicity of Isopropyl Methanesulfonate in Acute and 28-Day Studies https://doi.org/10.1002/em.21910.

19. John P. Guzowski, Jr. (2012) Understanding and Control of Dimethyl Sulfate in a Manufacturing Process: Kinetic Modeling of a Fischer Esterification Catalyzed by H2SO4. Https://dx.doi.org/10.1021/op200323j.

20. Tanju Karanfil et al. (2018) The role of chloramine species in NDMA formation https://doi.org/10.1016/j.watres.2018.04.033.

21. Andrew Teasdale (2019) Reflections on sartan nitrosamine contamination, Regulatory Highlights, OPRD https://doi.org/10.1021/acs.oprd.9b00270.

22. Andrew Teasdale (2019) Regulatory Highlights N-Nitrosamines OPRD https://doi.org/10.1021/acs.oprd.9b00535.

23. Myatt et al. (2016) Principles and procedures for implementation of ICH M7 recommended (Q)SAR analyses http://dx.doi.org/10.1016/j.yrtph.2016.02.004

42

THANK YOU for your kind attention!

ACKNOWLEDGEMENTS

LAURUS LABS LTD. and LHASA LIMITED