Phase 1/2 Study of the Timing and Efficacy of 3 mg Peg-GCSF in Neo/Adjuvant Dose Dense Breast Cancer Treatment Protocols.

Amol Patel  Peg-GCSF has similar efficacy at a dose of 60 µg/kg and 100 µg/kg. The conventional 6 mg SC dose was based on the maximum tolerable dose. In Japan, 3.6 mg dose was approved on the basis of dose finding studies. Peg-GCSF is an integral part of dose-dense chemotherapy protocols. Dose finding and scheduling study of peg-GCSF have not been conducted in Indian patients.  We conducted two-center phase 1/2 clinical study addressing the timing and efficacy of peg-GCSF in Indian breast cancer patients (CTRI no: 2021/07/034751). Three groups of timing administration were studied, namely 1, 6, and 24 hours post chemotherapy. The phase 2 part was the expansion of the best timing group. The primary objective was dose density, which was defined as receiving chemotherapy on < 3 days of scheduled date. Adriamycin/epirubicin cyclophosphamide (AC/EC) was administered q2 weeks. The total leucocyte (TLC) and absolute neutrophil (ANC) kinetics were studied. Other outcomes were incidence of grade 4 neutropenia, febrile neutropenia (FN), and requirement of additional doses of G-CSF. Bone pain, fever, and myalgia were studied for adverse effects.  From November 20 to December 21, 36 patients were enrolled. Patient characteristics are depicted in Table 1. Initially, three patients received the peg-GCSF in each timing group. One patient in each 1-hour and 6 hours needed G-CSF support for maintaining the dose density. The 24-hour group was carried to phase 2 part. Dose density was maintained in 97% of patients. None of the patient in 24-hour group had FN. Also, 4/30 patients had grade 4 neutropenia and required an additional dose of GCSF. Grade 3 or 4 bone pain was not noticed by any of the patients. During the first cycle, the mean ANC (cells/μL) was 5284, 20704, 3010, 6954 on D0, D + 3, D + 7, and D + 13, respectively (Fig. 1A-TLC and 1B-ANC). The mean ANC (cells/μL) rise on D + 3 in cycles 1, 2, 3, 4 was 23810, 29209, 32428,22455, respectively.  Dose density of AC/EC breast cancer protocol is maintained with peg-GCSF 3 mg. Post chemotherapy 24-hour timing of peg-GCSF administration remains as the standard. A phase 3 trial of 6 mg versus 3 mg is warranted.