A randomized, double-blind, placebo-controlled, single dose escalation phase 1 study to access the Pharmacokinetics and Pharmacodynamics of Single Intravenous Administration of SHR-1707

The study will consist of two parts: Subjects will be randomized to receive SHR-1707 as reflected by the guiding principle for the dose esclation/expansion phase. Each dose group includes a screening period, a baseline period, an observational period, and a safety follow-up period.

Inclusion Criteria:

1. Ability to understand the trial procedures and possible adverse events, voluntarily participate in the trial,
2. Male or female aged between 18 years and 45 years (inclusive) at the date of signed consent form in Part 1 and aged between 55 years and 80 years (inclusive) in Part 2
3. Total body weight of 45~100 kg (inclusive), with a body mass index (BMI) of 19~32 kg/m2 (inclusive) at screening and baseline
4. Subjects with good general health, no clinically significant abnormalities, or have underlying disease which is believed to have minimal impact on the study treatment in elderly subjects
5. WOCBP agree to take effective contraceptive methods

Exclusion Criteria:

1. Severe injuries or surgeries within 6 months before screening
2. ALT, or AST or total bilirubin level <1.5x upper limit of normal range (ULN) at screening or baseline visits
3. QTcF > 450msec (Male), QTcF > 470msec (Female) in 12-lead ECG test during screening and baseline
4. Known history or suspected of being allergic to the study drug.
5. Use of any medicine within 14 days (including any prescription, or over-the-counter medicine, herbal remedy or nutritional supplement, except for vitamins and acetaminophen with recommended dose [The dose of acetaminophen should be less than 2g/day, and no more than 3 days for continuous use]), or within 5 half-lives
6. Live (attenuated) vaccination within 1 month before screening
7. Blood donation or loss of more than 400 mL of blood within 3 months; or received blood transfusion within 3 months before screening.
8. History of alcohol abuse in the past 12 months of screening
9. History of illicit or prescription drug abuse or addiction within 12 months of screening
10. More than 5 cigarettes daily for 12 months before screening
11. Participation in clinical trials of other investigational drugs (include placebo) or medical devices within 3 months prior to screening
12. Researchers and relevant staff of the research center or other persons directly involved in the implementation of the program