This study was conducted as a second-line treatment of recurrent / progressive gastric cancer patients with FGFs / FGFRs genetic mutations in the Ib / II clinical trial. The maximum maximal tolerated dose (MTD) and 2-phase recommended dose in combination with INCB054828 and paclitaxel (recommended phase II dose, RP2D), and evaluate the safety and clinical efficacy of this combination therapy. This study consists of two steps: Phase 1 is a dose escalation study to determine the maximum tolerated dose and 2-phase recommended dose of weekly paclitaxel and INCB054828 combination therapy, and Phase 2 is the dose escalation study in combination with INCB054828 and paclitaxel Assess safety and tolerability and identify antitumor effects in stomach cancer with FGFs / FGFRs genetic mutations.

1. phase>

   - Approximately 3-12 patients will be enrolled. The dose escalation will be three patients registered for each cohort until the first dose-limiting toxicity appears during the four weeks of treatment and observation. 13.5mg, once a day begins to take. The paclitaxel is administered once a week for three consecutive weeks and then for one week, followed by a total of four weeks in one cycle.

2. phase> Phase 2 studies will be extended to a total of 30 patients with a two-phase recommended dose. Patients will be treated until the time of disease progression, intolerable toxicity, rejection of the patient, or withdrawal of consent. In its pre-screening phase, its next generation sequencing (NGS) is performed. Patients with FGFs / FGFRs genetic abnormalities may be enrolled in this study. If a patient has multiple genetic abnormalities, he or she will first be enrolled in a treatment group that targets a rare genetic abnormality. Registered patients will be treated on a continuous basis every four weeks.

Inclusion Criteria:

1. Patients who agreed in writing to the clinical study consent
2. Histologically or cytologically confirmed advanced gastric adenocarcinoma. Patients must have experienced objective radiological or disease progress with evidence during or after primary therapy with fluoropyrimidine and platinum.
3. FGFs / FGFRs have genetic variation on NGS.
4. Patients whose life expectancy is at least 3 months
5. If the Eastern Cooperative Oncology Group (ECOG) is 0 or 1
6. Measurable or assessable lesion based on RECIST 1.1 scale
7. Must be swallowed, should be able to take oral medication
8. Possible long-term function to receive chemotherapy.
9. Patients receiving anti-HER2 therapy for HER2 negative or HER2-positive primary treatment

Exclusion Criteria:

1. When chemotherapy exceeded the first treatment
2. Patients with multiple cancers
3. Severe hypersensitivity reactions to anti-FGFR2 agents either now or in the past
4. Patients with endocrine metabolic syndrome or history of calcium-phosphate homeostasis
5. Patients with ectopic neoplasm or history of soft tissue, kidney, large intestine, heart, or abdomen
6. Corneal lesions such as bullous keratopathy, corneal erosion, corneal erosion, corneal ulcer, corneal inflammation and keratoconjunctivitis were confirmed by ophthalmic examination
7. Patients with metastasis to the brain or meninges. However, patients who do not have symptoms and do not need treatment can register.
8. Clinically significant digestive system problems that can cause abnormalities in taking or absorbing clinical drugs
9. Patients with uncontrollable or significant cardiovascular disease
10. Patients with systemic infections requiring treatment
11. Patients who were exposed to paclitaxel at or before the taxane
12. If you undergo major surgery within 28 days before enrollment for this trial
13. Patients who received radiotherapy for gastric cancer within 28 days prior to enrollment for this trial. However, the investigation of bone turnover was conducted within 14 days before the registration for this trial
14. If you received general chemotherapy within 14 days of enrollment for this trial
15. Patients who are positive for human immunodeficiency virus (HIV-1) antibody test,
16. HBsAg results positive, HBV viral load greater than 2000 IU / ml (104 copies / ml), or HCV antibody test positive
17. Patients who are pregnant, lactating, or are likely to be pregnant
18. Anemia and hair loss are excluded if previous chemotherapy treatment has toxicity that is not recovered below grade 2.
19. Patients who are judged to have lost their ability to cope with dementia or other comorbid conditions
20. Other Patients who the examiner or the examiner deemed inappropriate for the clinical trial.