> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Suggestions for ‘Substantial Evidence’ Guidance
- URL: https://www.fdaweb.com/suggestions-for-substantial-evidence-guidance/
- Published: 2020-03-24T12:00:00.000Z
- Updated: 2026-09-14T16:08:35.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5146404

Pharmaceutical Research and Manufacturers of America (PhRMA) says it appreciates that FDA used a new draft guidance on demonstrating substantial evidence of effectiveness for human drug and biological products to complement and expand on an existing 1998 guidance to address new, innovative drug development approaches. In a comment [letter](https://www.regulations.gov/document?D=FDA-2019-D-4964-0062&ref=fdaweb.com), the trade group recommends that the agency clarify how the two guidances relate to each other. It also suggests that FDA re-issue a new draft guidance that consolidates still-relevant content from the 1998 guidance with the new content introduced in the 2019 guidance to ensure clarity for sponsors, regulators, and other stakeholders. “Consolidating the 1998 and 2019 guidance also would allow FDA to update the examples in the 1998 guidance with more recent examples,” the comment says.

PhRMA includes additional general and specific comments and recommendations.

The American Society of Gene and Cell Therapy [says](https://www.regulations.gov/document?D=FDA-2019-D-4964-0063&ref=fdaweb.com) it commends FDA attention within the draft guidance to evidence relating to trial designs, trial endpoints, and statistical methodology that were not addressed in the 1998 guidance. “We strongly agree that expedient delivery of safe and efficacious gene therapy to patients with no other options is of utmost importance, and we appreciate FDA efforts toward this end through clarification on the evidence required for these therapies,” the letter says.