Chk2 Inhibitor for Recurrent EpitheliAl periToneal, fallopIan or oVarian cancEr (CREATIVE Phase IA Trial)

This study aims to assess the safety and tolerability of PHI-101 in patients with platinum-resistance/refractory ovarian, fallopian tubal, and primary peritoneal cancer. This study also evaluates the pharmacokinetics of PHI-101 and efficacy of PHI-101 during treating platinum-resistance/refractory ovarian, fallopian tubal, and primary peritoneal cancer. PHI-101 is a CHK2 inhibitor that is a checkpoint kinase binding specifically to CHK2, rather than CHK1, and it inhibits the DDR system by inhibiting the ATM-CHK2 pathway, which is activated in response to DSBs. When a high-grade serous ovarian (HGSO) cancer cell line and various ovarian cancer cell lines (CAOV3, OVCAR3, SK-OV-03, and SW626) were treated with PHI-101 in a non-clinical study, the therapeutic effect of PHI-101 against ovarian cancer was demonstrated by a decrease in viability of ovarian cancer cells. In addition, a stronger growth inhibition effect was observed compared to that of treatment with olaparib or rucaparib alone, and a much stronger inhibition effect was observed when concomitantly used with paclitaxel, cisplatin, and topotecan. Based on the aforementioned results of the non-clinical studies, the potential of PHI-101 as a new treatment or concomitant cytotoxic chemotherapeutics for patients with ovarian cancer who are resistant to existing antineoplastic drugs was confirmed.

In this study, a maximum of 6 dose levels (cohorts) were planned for daily oral administration of PHI-101. Subjects who meet the inclusion/exclusion criteria of this study will be enrolled in each cohort and assessed for safety and tolerability after administering PHI-101 to determine the MTD. Subjects will be enrolled sequentially starting from the low-dose cohort, and DLT will be assessed for the first 28 days (Cycle 1) after the first dose of PHI-101. Before DLT is assessed in a specific cohort, enrolling a subsequent subject in the next higher dose cohort will not be allowed. According to the accelerated 3+3 design, the accelerated dose escalation scheme, which assesses DLT in 1 subject in each cohort ('single subject cohort'), is applied until toxicity (ADRs) related to PHI-101 ≥ \[CTCAE version 5.0\] grade 2 occurs. If ADRs ≥ grade 2 do not occur in 1 subject, DLT can be assessed in one level higher cohort according to the SRC's recommendation. If an ADR ≥ grade 2 occurs in a specific cohort, the accelerated 3+3 design will be immediately switched to the standard 3+3 scheme, and 2 additional subjects will be enrolled in that cohort (1 subject + 2 additional subjects) to assess DLT during 1 cycle. After switching to the standard 3+3 scheme, 3 to 6 subjects will be enrolled in each cohort. If no DLT is observed in the first 3 subjects, DLT can be assessed in one level higher cohort according to the SRC's recommendation. If DLT is observed in 1 out of 3 subjects (DLT: 1/3 subject), that cohort will be expanded to 6 subjects by enrolling 3 additional subjects. If 2 out of 3 to 6 subjects experience DLT (DLT: 2/3 to 6 subjects), this means that the MTD is exceeded. Thus, additional enrollment will be ended for that cohort. The one level lower cohort will expand to 6 subjects (If 6 subjects were already enrolled in that cohort, additional enrollment is unnecessary). A subject not evaluable for DLT (withdrawal for reasons other than AEs or ADRs, or less than 20 out of 28 doses of PHI-101 were administered during Cycle 1) may be replaced by another subject according to the judgment of the investigator (decision/recommendation of the SRC, if necessary). If a subject in the single subject cohort is not evaluable for DLT, a substitute will be enrolled in the same cohort (1 subject + 1 additional subject) to assess DLT. If it is determined not to replace the subject not evaluable for DLT, the subject will be considered to have experienced DLT when the dose escalation is decided. If DLT is observed in \> 1 out of 6 subjects in a specific cohort (χ) and DLT is observed in ≤ 1 out of 6 subjects in the cohort (χ-1) that is one level lower than the specific cohort, the one level lower cohort (χ-1) will be considered as the MTD. The dose of PHI-101 will be escalated until an MTD is determined. If the MTD is not determined at the MPD, dose escalation will be ended at that dose (Addition of cohorts may be reviewed by and discussed with the SRC, if necessary, but reporting to the MFDS and the IRB and protocol amendment should occur first.) According to the schedule of activities (SOA), observation, questioning, examination, and tests to assess the safety and tolerability of PHI-101, PK sampling to assess PK, and tumor response assessment to explore efficacy will be performed. After the EOT of PHI-101, the EOT visit will take place. Survival of subjects and initiation of new antineoplastic therapy will be periodically checked until the EOS. The follow-up will be performed for 1 year after the EOS to obtain such information.