G1 Therapeutics, Inc. announced that the Company has initiated PRESERVE 3, a Phase 2, randomized, open-label study of COSELA™ (trilaciclib) administered with first-line platinum-based chemotherapy and the immune checkpoint inhibitor avelumab maintenance therapy in patients with untreated, locally advanced or metastatic urothelial carcinoma (mUC). Myeloprotection and anti-tumor efficacy endpoints are being assessed in this study. Initial results of this study are expected in the second half of 2022. Patient recruitment in Preserve 3 is now underway. The study will enroll approximately 90 patients, who will be randomly assigned to one of two treatment arms (A or B). Arm A will receive gemcitabine/platinum chemotherapy followed by avelumab maintenance therapy. Arm B will receive COSELA prior to gemcitabine/platinum chemotherapy followed by COSELA plus avelumab maintenance therapy. Standard of care gemcitabine/platinum chemotherapy (with or without the addition of COSELA) will be administered intravenously in 21-day cycles and standard of care avelumab maintenance therapy (with or without the addition of COSELA) will be administered intravenously in 14-day cycles. There will be two stratification factors for randomization: presence of visceral metastasis (yes or no), and initial platinum-based chemotherapy to be administered (cisplatin or carboplatin). Patients enrolled in the study will be eligible to receive 4 to 6 cycles of platinum-based chemotherapy. Patients without progressive disease as per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 guidelines (i.e., with an ongoing complete response, partial response, or stable disease) after platinum-based chemotherapy will be eligible to receive avelumab maintenance therapy (with or without COSELA) until disease progression, unacceptable toxicity, withdrawal of consent, Investigator decision, or the end of the trial, whichever occurs first. The primary endpoint is to evaluate the anti-tumor efficacy of COSELA when combined with platinum-based chemotherapy and the checkpoint inhibitor avelumab maintenance therapy as measured by progression-free survival (PFS) during the overall study. Key secondary endpoints include; evaluation of the anti-tumor efficacy of COSELA as measured by the objective response rate (ORR). disease control rate, duration of objective response (DOR); PFS in the maintenance period; overall survival (OS) and probability of survival (POS) at Month 16; evaluation of the myeloprotective effects of COSELA on chemotherapy-induced myelosuppression; and assessment of the safety and tolerability of COSELA in patients receiving platinum-based chemotherapy followed by avelumab maintenance therapy.