Lack of efficacy

This is a long-term follow-up study to evaluate the safety and durability (efficacy) of response to EN3835 compared to placebo in participants who were treated in EN3835-210 or the pivotal Phase 3 parent studies for the treatment of AC of the shoulder (frozen shoulder).

Inclusion Criteria:

1. Have been enrolled and completed the EN3835-210 or pivotal Phase 3 parent studies (for Study EN3835-223 eligibility, completed participants are those who were assessed for safety and obtained ASES scores at Day 95/EOS Visit; does not include early terminated participants).

2. Be willing not to use pain medications for the duration of the study period and for 2 weeks prior to the Day 180 visit. Pain medications include but are not limited to: barbiturates, benzodiazepines, methadone, buprenorphine, opioids (e.g., codeine, heroin, hydrocodone, hydromorphone, morphine, oxycodone), and cannabis.

   Note: NSAIDs (ibuprofen, etc.) are allowed.

3. Be willing to undergo MRI of the affected shoulder as required by the protocol.

4. Be able to read, understand, and independently complete patient reported outcome instruments in English.

5. Be willing and able to cooperate with the requirements of the study.

6. Be adequately informed and understand the nature and risks of the study and be able to provide consent.

Exclusion Criteria:

1. Is from a vulnerable population, as defined by the US Code of Federal Regulations (CFR) Title 45, Part 46, Section 46.111(b) and other local and national regulations, including but not limited to, employees (temporary, part-time, full time, etc.) or a family member of the research staff conducting the study, or of the sponsor, or of the contract research organization, or of the IRB/IEC.

2. Plans to receive (or received prior to Day 180) any invasive or minimally invasive (ie, steroid injections, shoulder manipulation, surgery, etc.) procedures to the affected shoulder during study participation.

   Note: PT is allowed. Any PT received should be captured in the respective electronic case report form (eCRF).

3. Has any contraindications for MRI (implant containing metal, internal metallic object, permanent cosmetics/make-up/tattoos-with exemption of the area to be treated/reviewed, claustrophobia, syncope, low blood pressure, epilepsy, asthma, anemia, or sickle cell disease) as determined by the technologist, the radiologist, and/or investigator performing imaging.

4. Has any other conditions that, in the investigator's opinion, might indicate the participant to be unsuitable for the study.

All participants that have completed the EN3835-210 study or the pivotal Phase 3 studies in which they were enrolled.