Paclitaxel Focus of Device Controversy

The technology behind percutaneous treatment for the coronary arteries has advanced much more rapidly than for the peripheral vasculature, but the use of paclitaxel, a chemotherapeutic agent, as a go-to antiproliferative for any part of the anatomy could be near an end. The FDA published a letter to physicians in January stating that a medical journal article suggested that paclitaxel-bearing drug-eluting stents (DESs) and drug-coated balloons (DCBs) for the peripheral arteries had demonstrated an unexpectedly high long-term mortality rate compared to bare-metal stents and non-coated balloons. However, the conclusions drawn in that medical journal are the subject of a dispute that may determine whether paclitaxel has any future at all in the circulatory system.

The article in the Journal of the American Heart Association describes a meta-analysis covering more than two dozen randomized, controlled trials for both DES and DCB devices, all coated with paclitaxel. The authors stated that all-cause death at both two and five years for paclitaxel devices was significantly higher than for their non-eluting counterparts when used in the arteries of the lower extremities, but that more study is warranted, in part because only two of those studies ran for a full five years. The authors hypothesize that the crystalline form of paclitaxel, which has a longer half-life than other formulations, may be the culprit.

Medtronic, the Dublin-based manufacturer of the In.Pact Admiral DCB, took issue with the JAHA authors in an article in the Journal of the American College of Cardiology, stating that there is no statistically significant difference in mortality between DCBs and plain angioplasty balloons at five years. As is the case with the JAHA analysis, there are a number of moving parts in the Medtronic summary, including that the data are drawn from patients in a variety of nations that exhibit different patterns of post-procedural care, not to mention differences in the use of dual anti-platelet therapy (DAPT). The company argued that much of the difference in mortality outcomes could hinge on the more aggressive use of DAPT in patients treated with bare-metal stents and plain angioplasty balloons.

Whether any of this clinical data will translate into regulatory action is impossible to forecast, but the FDA advised that it still sees the benefit of these devices as outweighing the risks. If Medtronic’s view – that the mortality rates at five years out, at least in statistical terms – wins the day, device makers might be on the hook for nothing more than a somewhat greater post-market surveillance liability. Makers of DCBs might already be on that track, as the Centers for Medicare & Medicaid Services (CMS) declared it will pay what clinicians and device makers see as a sub-optimal rate for these devices, unless and until CMS sees some compelling data that the difference in cost between DCBs and plain balloons is justified by outcomes.

New Guidance from FDA: When to Submit a 510(k) for a Change to a Cleared Medical Device

Courtney A. Stevens, Esq. |Senior Attorney, Medmarc Loss Control

FDA’s newest guidance for medical device manufacturers, Deciding When to Submit a 510(k) for a Change to an Existing Device, issued August 8, addresses a question manufacturers commonly face,—when a 510(k) is necessary for a change to an already cleared device. Manufacturers’ failures to submit 510(k)s are frequently cited in warning letters as rendering a device adulterated. As such, it’s an issue medical device companies can’t be too careful in scrutinizing. Thankfully, this guidance does provide such much-needed clarity on exactly when a 510(k) is necessary, and when processing the change in accordance with Quality System (QS) requirements (e.g., documentation of changes and approvals in the master record, verification and revalidation, etc.) is sufficient.

The confusion over whether a 510(k) is necessary is largely due to the subjective, relative language in the regulations, requiring device-makers to submit a 510(k) when a change “could significantly affect the safety or effectiveness of the device.” (21 CFR 807.81 (a)(3)). The Agency tried to clarify its interpretation of that language in its first guidance document on this issue, published in 1997, but clearly, as evidenced by the frequency with which the manufacturers’ determination of “significant” changes differed from the Agency’s, greater clarity was needed still. (Once finalized, this draft guidance will supersede the 1997 Guidance on the subject.)

This guidance document improves upon its predecessor by providing a number of exacting flow chart-decision trees to guide manufacturers through the determination of a 510(k)s’ necessity with regard to different types of changes.

It begins by setting out the guidance principles to be first considered in determining the propriety of a 510(k), which I briefly summarize here:

  • Modifications made with intent to significantly affect safety or effectiveness of a device. This is the same language as is found in the regulations, and its meaning is fleshed out in the remainder of the document.
  • Could “significantly affect” evaluation and the role of testing. In order to determine significance of the effect, manufacturers must conduct risk-based assessments.
  • Unintended consequences of changes. One component deemed to make up a “significant effect” is if the change would result in unintended consequences or effects. The draft guidance provides sterilization as an example which may affect device materials, thereby affecting performance of the device.
  • Use of risk management. Here, the draft refers to ISO 147981: Medical devices – Application of risk management to medical devices, and instructs manufacturers to utilize an assessment combining the probability of occurrence of harm and the severity of that harm in determining “significant effect.”
  • Evaluating simultaneous changes. Even though changes may occur simultaneously, each change should be assessed individually and in combination.
  • Appropriate comparative device and cumulative effect of changes. In making the determination of a 510(k)’s propriety, manufacturers need to consider (1) how different a change makes the device from its initial or most recent iteration as described in their most recently cleared 510(k); and (2) the cumulative effect of all changes since the last 510(k) cleared for this device. That is, though previous changes did not require a 510(k) when made in isolation, does the cumulative effect of this change with those previously made nor warrant a 510(k), even if it, by itself, would not?
  • Documentation required. Even if a manufacturer determines a 510(k) is appropriate for a particular change, this does not alleviate them from compliance with all existing QS requirements, including all documentation, verification, and validation duties.
  • 510(k) submission for modified devices. When a 510(k) is submitted for a device with multiple modifications since its last cleared 510(k), the 510(k) should describe not only the most recent change that warranted the 510(k), but also all previous modifications even though they did not merit the submission of 510(k)s in and of themselves.
  • Substantial equivalence determination. Manufacturers need understand that submission of a 510(k) for a change pursuant to everything outlined in the regulation and this guidance document does not assure that a substantial equivalence determination will be provided.

 

With these considerations in mind, manufacturers may proceed to the different parts of the guidance instructing them on decision-making for different kinds of changes—labeling, control mechanisms, operating principles, etc. In each of these, manufactures will find the aforementioned decision trees to guide them through submission criteria.

An example of the flow charts included in this draft guidance:

8.16 - guidance flowchart

In addition to charts guiding decision making, the guidance also provides examples of documenting changes and written regulatory change assessments.

This should go a long way in facilitating manufacturers’ understanding of when 510(k)s for changes are necessary, and reduce the number of warning letters for companies’ failure to submit them, accordingly.