13D Filing: Lansdowne Partners and Summit Therapeutics PLC (ADR) (SMMT)

If the filing
person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D/A, and
is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box o.

Note: Schedules
filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for
other parties to whom copies are to be sent.

* The remainder
of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of
securities and for any subsequent amendment containing information which would alter disclosures provided in the cover page.

The information
required on the remainder of this cover page shall not be deemed to be “filed” for the purposes of Section 18 of the
Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall
be subject to all other provisions of the Act (however, see the Notes).