(Adds analysts' comments in paragraphs 4 and 9, G1 Therapeutics in paragraph 7, Blueprint Medicines in paragraph 9, updates share movement)

June 5 (Reuters) - Shares of several cancer drug firms surged on Monday after the companies reported positive clinical trial data from their therapies at an ongoing industry conference in Chicago.

Day One Bio, Immunogen Inc, Evaxion Biotech A/S and G1 Therapeutics Inc rose after presentations at the ongoing annual American Society of Clinical Oncology (ASCO) meeting.

ImmunoGen Inc's experimental drug, Elahere, to treat a type of ovarian cancer showed 35% reduction in the risk of tumor progression or death compared to chemotherapy in a late-stage study.

A William Blair note issued on Monday was titled "Practice-Changing Data Elevate Elahere to Global Stage". The drugmaker's shares rose nearly 7% to $15.36.

Shares of Day One surged 14% to $15.5 after the company's experimental therapy for a type of brain tumor significantly reduced tumor in 67% of patients aged over 6 months to 25 years in a mid-stage study.

Shares of Evaxion rose 5.4% to $1.55 after the smaller drug developer said its vaccine to prevent a type of skin cancer met safety goals in an early-stage study.

Another small biotech company, G1 Therapeutics, rose 7.25% to $2.81 after its experimental drug to treat a type of breast cancer increased immune response generating T cell function and removed any residues of the invasive cancer in a mid-stage study.

On the other hand, Arcus Biosciences Inc fell nearly 9% to $19.13 after updated data on its experimental lung cancer showed a lower benefit in cutting the risk of disease progression, compared to earlier data from a mid-stage trial.

Shares of Blueprint Medicines Corp fell 9.4% to $52.76 after analysts flagged potential safety issues about its experimental drug to treat a type of lung cancer. (Reporting by Manas Mishra and Mariam Sunny in Bengaluru; Editing by Shailesh Kuber)