CMC Readiness Issues at FDA End-of-Phase 2 and Pre-NDA/Pre-BLA Meetings

CMC readiness at FDA End-of-Phase 2 and pre-NDA/pre-BLA meetings: recurring issues and their effect on submission timing and content

Chemistry, manufacturing, and controls (CMC) readiness is one of the most frequent sources of friction in FDA milestone meetings. Meeting minutes and review documents in Drugs@FDA and CBER approval packages show a consistent pattern. At End-of-Phase 2 (EOP2), FDA focuses on regulatory starting materials, specifications, dissolution methods, and whether the Phase 3 formulation will be the commercial one. At pre-NDA and pre-BLA meetings, the discussion shifts to whether the application will be complete on day one: enough stability data, process validation, comparability data, extractables and leachables (E&L) data, impurity qualification, and inspection-ready facilities.

The consequences show up in four ways: data FDA requires in the original application, negotiated "late component" windows (typically 30 days), warnings of refusal to file, and, where advice was not followed, major amendments or Complete Response Letters (CRLs).

Key takeaways

• Stability data is the main timing lever. For NDAs, FDA's baseline is generally 12 months of long-term data on three primary batches at submission; biologics minutes often reference shorter packages (about 6 months). It has accepted 9 months, or 3 to 6 months, with a 30-day update in specific cases. Later updates risk being treated as a major amendment or not reviewed in the cycle ^{227231518527533}.
• Process validation is not a "late component" for biologics. FDA told the Opdivo sponsor that PPQ data could not follow the initial BLA by 45 days ⁴⁵³. FDA told the Keytruda sponsor it could not accept an incomplete CMC package, and offered a choice between a complete December 2013 BLA and a rolling submission ending with PPQ data ⁴⁴⁹.
• Impurity and E&L gaps draw refuse-to-file warnings. These warnings appear repeatedly in pre-NDA minutes ^{136139141143376393}. Where E&L advice was not followed, the result was a CRL or a resubmission requirement ^385387420.
• Thin CMC briefing packages lead to extra meetings. FDA has recommended separate CMC-only pre-NDA or CMC-specific EOP2 meetings when the package lacked usable CMC content ¹⁹¹²²⁵.

What FDA guidance says each meeting should cover

FDA's guidance IND Meetings for Human Drugs and Biologics: Chemistry, Manufacturing, and Controls Information is the anchor document ⁴⁰⁸. For EOP2, it identifies topics including product and cell bank characterization, bioassay suitability, removal of product- and process-related impurities, and the bioactivity of product-related substances and impurities. For conventional biologics, it adds facility-design coordination, process-validation considerations, and the potency assay ⁴⁰⁹. The EOP2 background package should update the description of materials used or planned for Phase 3 and place completed studies in the context of the prospective NDA strategy ⁴¹¹.

The same guidance places the pre-NDA/pre-BLA meeting about six months before submission. It frames the meeting around filing and review obstacles. The sponsor should assure FDA that the application will contain adequate stability data under protocols agreed at EOP2, and that all manufacturing, testing, and packaging facilities will be ready for inspection by the time of submission ^337338339.

For expedited programs, the guidance Expedited Programs for Serious Conditions: Drugs and Biologics recommends that sponsors seeking rolling review obtain preliminary agreement at or before the pre-NDA/pre-BLA meeting on the schedule and on which portions will arrive separately. FDA generally accepts only a complete, review-ready section, such as the entire CMC section. At its discretion, it may accept a reviewable subsection that is missing items such as final consistency-lot or long-term stability data ³⁴⁰³⁴¹. The guidance also lets FDA decide case by case how much manufacturing information is needed at submission versus approval. Sponsors should raise their CMC plan no later than the pre-NDA/pre-BLA meeting ³⁴².

For cell and gene therapies, FDA guidance asks sponsors to:

• make commercial-scale changes and demonstrate comparability before trials intended to support effectiveness ⁴⁸²;
• qualify a potency assay before those trials and validate it before licensure or BLA submission ⁴⁸⁴⁴⁸⁵;
• justify the number of PPQ batches rather than relying on a fixed minimum ⁴⁶⁹.

The draft comparability guidance warns that extensive changes shortly before BLA submission call for comprehensive comparability evidence and may require additional PPQ ⁴⁶⁷.

End-of-Phase 2: starting materials, specifications, and the to-be-marketed product

Regulatory starting materials and drug substance specifications

EOP2 CMC minutes most often record FDA conditionally accepting starting materials while deferring final judgment to NDA review. Two examples show the range:

• Xtandi (NDA 203415): FDA could not assess the proposed starting materials from the information supplied. It asked for reference standards, starting-material assays, impurity information, and supplier audit and change-control details. Drug substance specifications and genotoxic impurity controls were deferred to NDA review ¹⁸¹¹⁸².
• Gemtesa (NDA 213006): FDA agreed to the starting-material designations on condition that the synthetic schemes appeared in the NDA. Final acceptance criteria and impurity controls were left for review, and FDA noted that the impurity-limit justification and a comprehensive potential-impurity list were missing ¹⁹²¹⁹³.

Similar conditional outcomes appear for Cerdelga ¹⁸⁵¹⁸⁶, Vistogard (where FDA offered a DMF route for the CMC information) ¹⁸⁸¹⁸⁹, and the AbbVie Viekira Pak program, where FDA required specification justifications that weigh impurity rejection against manufacturing capability ¹⁹⁴¹⁹⁵.

The practical effect is mostly on content. These issues rarely shift the timeline, but they predetermine what Module 3 must justify.

Dissolution methods

FDA used EOP2 to push back on non-discriminating or unjustified test methods. In the Xtandi program, FDA did not agree to replace capsule dissolution with a rupture test without justification. It recommended a test able to distinguish batches that are within specification from those that are not ¹⁸¹. For Allegra-D 24 Hour, FDA wanted a discriminating method agreed as soon as possible, preferably before stability studies began ⁵³⁵⁴.

The timing risk is concrete. In the Lipofen program, FDA said a bridging study would be needed if it disagreed with the dissolution conditions already used in NDA stability studies ²²³. FDA reserved acceptability of the method and acceptance criteria for NDA review in many pre-NDA exchanges, including Khedezla, Hysingla ER, and a sertraline NDA ⁵⁰⁵¹⁴⁶. In the sertraline case, FDA told the sponsor it could get earlier method feedback by amending the IND with a complete report, which typically took up to three months to assess ⁴⁷⁴⁸.

Formulation bridging

Formulation decisions made at EOP2 can affect the whole clinical package:

• Ojjaara (NDA 216873): FDA expected the new tablet to meet 80 to 125% bioequivalence against the earlier capsule and wanted comparative PK results before the tablet was used in Phase 3. If the formulations were not bioequivalent, dose-finding and other completed studies would need to be repeated with tablets ³²³³.
• Jornay PM (NDA 209311): FDA rejected an in vitro bridge between formulations that differed in manufacturing site and process. Given the product's complex release mechanism, it recommended a relative bioavailability study instead ²⁸.
• Ibrance (NDA 207103): At the pre-NDA stage, FDA said it preferred the pivotal-trial formulation to match the commercial product. It said in vivo bioequivalence offered the best assurance for major formulation changes ³⁴³⁵.

Incomplete EOP2 CMC packages

When the EOP2 package lacked usable CMC content, FDA asked for another meeting. For Monoferric (NDA 208171), FDA could not find CMC information referenced in the package. It said it was unclear whether the available CMC information would support an NDA, and it recommended a separate CMC-specific EOP2 meeting ¹⁹¹.

Pre-NDA and pre-BLA: completeness of the application

Stability data at submission

Stability is the CMC topic most directly tied to submission timing. FDA described fewer than 12 months of long-term data in an original NDA as normally a filing issue ²²⁷. Many minutes nonetheless record negotiated exceptions, usually with tight conditions.

Two cross-cutting points emerge. First, a pre-meeting agreement on filing adequacy does not settle expiry dating. FDA repeatedly reserved shelf-life decisions for review ^520522523533. Second, filing with limited data is at the sponsor's risk. FDA told the paricalcitol sponsor that later data might not be reviewed and could yield a short expiry ⁵³², and gave a similar warning in the Qsymia program ⁵³⁷. FDA also refused a supplier-qualification late component for the Zynrelef Kit that would have allowed an earlier filing, and required all qualification data at submission ⁵³⁶.

Process validation and PPQ (biologics)

Pre-BLA minutes show that FDA treats process validation as part of a complete CMC package:

• Opdivo: FDA said process validation was not a limited component suitable for later submission under the PDUFA V approach, and rejected a 45-day post-submission timeline for PPQ data ⁴⁵³.
• Kymriah (BLA 125646): At mid-cycle, FDA found that the process-validation lots were made before the protocol was approved and before the commercial process was established, using clinical batch records. FDA called this inconsistent with its pre-BLA recommendation. These were major CMC issues requiring resolution for approval ²⁶⁵²⁶⁶.
• Blincyto (BLA 125557): FDA required BLA data showing that pilot-scale filling and lyophilization models represented the commercial processes ⁴⁴⁷.
• Ilaris (BLA 125319): FDA listed the aseptic-processing validation, container closure integrity, sterilization, hold-time, media-fill, and lyophilization data it expected. It called the pre-meeting CMC package too general to judge completeness ⁴²⁵.

Comparability after manufacturing changes

Late process, site, or equipment changes drew specific data requests:

• Blincyto: For comparability between process 4 and process 5 material, FDA asked for biological activity assay designs and all raw assay data, not only means ⁴⁴⁷⁴⁴⁸.
• Daxxify (BLA 761127): FDA rejected the planned BLA content for an equipment upgrade. It required pre- and post-change comparability data, an E&L risk assessment, media-fill and sterilization validation, and capping validation ⁴⁶⁴.
• Adcetris: For a manufacturing suite move, FDA said additional comparability studies were not needed if the equipment was the same or equivalent. All comparability data still belonged in the BLA, and facility changes would be evaluated at inspection ⁴⁶⁰⁴⁶¹.
• Portrazza (BLA 125547): Whether a manufacturing site needed full data in the original BLA depended on whether the sponsor sought that site's approval at licensure or in a supplement ⁴⁵⁸⁴⁵⁹.
• Breyanzi (BLA 125714): At the pre-BLA meeting, FDA discussed specification acceptance criteria, potency, viability, shelf life, and a rolling submission. Module 3 arrived as the final rolling component. A later major amendment for substantial new manufacturing and facility information moved the PDUFA goal date to November 16, 2020. The record does not tie the amendment to a specific meeting issue ⁸³⁸⁴⁸⁵.

Potency assays

Potency assay readiness can change what goes into the BLA itself. For Prehevbrio (BLA 125737), the sponsor could not provide all the potency assay information requested at pre-BLA meetings. FDA considered the in vitro assay insufficiently developed and validated, and advised removing it from the BLA, release specifications, and stability plans. Further development was to continue under the IND or in a post-licensure prior-approval supplement ²⁶⁸.

For Portrazza, FDA required a more robust package to justify dropping a binding potency assay from release and stability specifications ⁴⁵⁸. For Repatha (BLA 125522), FDA would not yet accept substantially reduced stability testing of drug substance validation lots, and warned that missing data could prevent shelf-life support ⁴⁵⁶.

Impurities, mutagenic impurities, and qualification

FDA's pre-NDA impurity advice is consistent and often comes with a refuse-to-file warning:

• Hysingla ER (NDA 206627): FDA set a limit of not more than 1.5 mcg/day for genotoxic impurities unless justified, required a Module 2 impurity table, and warned it might refuse to file if a structural-alert impurity above that level was not qualified ^134135136.
• Tivorbex, Narcan, and Targiniq: FDA gave similar warnings, tied to qualification above ICH thresholds and ICH M7 control strategies ^{137139140141142143}.
• Kyprolis (NDA 202714): At EOP2, FDA disagreed that genotoxicity had been fully assessed because the tested lots did not represent the impurity profile of other relevant lots ¹¹⁷.
• Viltepso (NDA 212154): FDA said that if nonclinical impurity-qualification studies were needed, their final reports were expected in the original NDA, not afterward ¹³².
• Zurampic (NDA 207988): FDA required an NDA table covering each structural-alert impurity's in silico results, toxicological assessment, and purge or control, at or below ICH M7 thresholds ¹¹⁹¹²⁰.

Container closure, extractables and leachables, and device constituents

E&L is the clearest example of pre-NDA advice that, when not followed, led to non-approval:

• Cocaine hydrochloride nasal solution (Numbrino, NDA 209575): The CRL stated that leachables had not been assessed on at least three to-be-marketed batches at multiple stability timepoints, "as advised" at the pre-NDA meeting. It required a new multibatch leachables study covering every marketed container closure system ⁴²⁰⁴²¹. The pre-NDA minutes for the same application (Numbrino) show that FDA had described those data as essential to setting shelf life ^373374375.
• Brixadi (NDA 210136): FDA had advised multibatch, multi-timepoint leachables testing. In review, it found the E&L evaluations inadequate, new data could not be reviewed in that cycle, and final reports were required with resubmission ³⁸⁵³⁸⁶.
• Anjeso (NDA 210583): The original NDA received a CRL that cited an inadequate E&L evaluation: incompletely identified leachables, testing of one aged lot at one timepoint, and monitoring of only two compounds ³⁸⁷.
• Triferic (NDA 206317): FDA said any leachable of concern found in an ongoing study had to be resolved before approval ³⁷¹³⁷².

Device-constituent coordination can also affect timing. For Duopa (NDA 203952), FDA said cross-labeled devices submitted through 510(k) could not be cleared before NDA approval, so submission and clearance timing had to be coordinated ³⁸². For Nucala (BLA 761122), FDA told the applicant to include the actual E&L study reports in the BLA. FDA later requested them, and they were submitted during review ³⁹⁵.

Facility inspection readiness

Pre-NDA and pre-BLA minutes almost always include standard advice: every manufacturing facility should be ready for GMP inspection at submission, and the application should list each site's FEI number, responsibilities, DMF reference, and onsite contact. Examples include Ryzodeg 70/30, Vimizim, Signifor LAR, Vyondys 53, and Sylvant ^{309277313314315}.

For Odomzo and Lonsurf, FDA also asked sponsors to identify non-commercial sites that made batches supporting the application ³²⁴. For Firdapse, FDA noted that facility information could be submitted before the complete NDA. FDA could not request inspections before receiving the NDA but would work to make inspections timely afterward ³¹¹³¹². For Emtriva, FDA asked the sponsor to state each site's inspection readiness. It also advised against delaying the CMC presubmission over unresolved starting-material questions, since those could be agreed during review ²³⁴.

Insufficient CMC content in meeting packages

The quality of the briefing package affects how useful the meeting is. For Odomzo, FDA found no specific CMC information in the briefing materials and strongly recommended a CMC-only pre-NDA meeting before submission ²²⁵²²⁶. For Ryaltris, FDA asked the sponsor to request a separate CMC pre-submission meeting ¹³⁰. For Mylotarg, a CMC-only Type C meeting led to requests for a separate 3.2.S module and BLA data on a newly identified attribute ⁴⁶²⁴⁶³.

How meeting outcomes translated into submission timing and content

Practical implications for CMC teams

1. Treat EOP2 as the point to lock the commercial formulation and the dissolution method. Changes after stability or Phase 3 start can trigger bridging studies or repeated clinical work ²²³³².
2. Plan stability backward from the submission date. The default expectation is 12 months long-term and 6 months accelerated on three primary batches per strength ⁵³¹⁵³⁵. Any exception needs explicit, documented agreement with a defined update window ²³¹⁵²⁷.
3. For biologics, complete PPQ and comparability before the BLA rather than relying on late submission ^453449467.
4. Close E&L and mutagenic impurity programs with multibatch, multi-timepoint data before filing. This is where unaddressed pre-NDA advice has most visibly led to CRLs ⁴²⁰³⁸⁷.
5. Request a dedicated CMC meeting when the general milestone meeting cannot cover CMC adequately. FDA has itself recommended this when packages were thin ¹⁹¹²²⁵.