Faeth Therapeutics reported the preliminary results from the ongoing, open-label, single-arm study evaluating serabelisib and sapanisertib, the two oral agents that make up PIKTOR, in combination with paclitaxel. The trial enrolled patients whose tumors harbored a PI3K/AKT/mTOR pathway mutation and who had received at least one prior line of therapy.
An investigational combination targeting the PI3K/AKT/mTOR pathway produced confirmed responses in 12 of 36 evaluable patients (33%) with previously treated advanced endometrioid endometrial cancer in the Phase 2 PIK-201 trial.
David Starks, PIK-201 and GOG Foundation principal investigator and Gynecologic Oncologist at Avera Cancer Institute in Sioux Falls, South Dakota, described the clinical need behind the study.
“We need more treatment options for patients whose advanced endometrial cancer has progressed after platinum chemotherapy and immunotherapy.”
New Approach After Taxanes and Immunotherapy
The ongoing, open-label, single-arm Phase 2 trial FTH-PIK-201 is being conducted in collaboration with The GOG Foundation, Inc. It evaluates PIKTOR, an investigational all-oral combination of serabelisib and sapanisertib, given with paclitaxel in patients with advanced endometrioid endometrial cancer harboring a PI3K/AKT/mTOR pathway mutation after at least one prior line of therapy.
Patients had received a median of two prior lines of therapy (range, one to four), and 15 of 42 (36%) had received three or more. All 42 had previously received taxane-based chemotherapy, and 41 (98%) had received immunotherapy. Distant metastases were present in 76% of patients, and 48% had diabetes or prediabetes at baseline.
PIKTOR Plus Paclitaxel Response Rate in PIK-201
At the October 30, 2026 efficacy cutoff, Faeth reported the following results.
Confirmed objective response rate (ORR) was 33% (12 of 36). One additional patient had a partial response and discontinued before the confirmatory scan, yielding an ORR of 36% (13 of 36) when that response was included.
Confirmed ORR in the PIK3CA-mutated subgroup was 44% (7 of 16). This estimate is descriptive and comes from a small subgroup.
Disease control rate was 83% (30 of 36), including complete responses, partial responses, and stable disease.
Median progression-free survival (PFS) was 7.4 months in all 42 treated patients by preliminary Kaplan-Meier estimation (95% CI, 5.3 months to not reached). The estimated six-month PFS rate was 62% (95% CI, 43%-75%).
Six treated patients discontinued before their first post-baseline scan and were excluded from the response analysis. Three discontinued because of early disease progression and three for reasons unrelated to treatment. All six were included in the PFS analysis.
Sixteen patients remained on treatment at the efficacy cutoff, including nine of the 12 confirmed responders and seven patients whose best response was stable disease. One patient converted from stable disease to a partial response after 20 months of treatment. The supplied release reports Kaplan-Meier estimates in text and provides no survival curve or response plot.
Severe Treatment-Related Events
At the October 23, 2026 safety cutoff, 64% of patients had experienced a grade 3 or higher treatment-related adverse event. Neutropenia, reported as a grouped term that included decreased neutrophil count, occurred in 36% overall and was the most frequent grade 3 or higher treatment-related event, at 26%.
Hyperglycemia occurred in five patients (12%), including one grade 3 event (2%). Stomatitis occurred in 21%, including one grade 3 event (2%). Patients did not receive prophylactic steroid mouthwash.
Treatment-related discontinuation occurred in two patients (5%). The events were headache and dizziness. No treatment-related deaths were reported.
What Faeth Therapeutics’ Phase 3 Trial Would Need to Establish
Faeth plans to advance PIKTOR plus paclitaxel into a registrational Phase 3 trial, subject to regulatory alignment. The single-arm design leaves the incremental benefit of adding serabelisib and sapanisertib to paclitaxel unresolved. Longer follow-up will help characterize response durability and refine the preliminary PFS estimate, while a controlled trial would be needed to assess comparative efficacy and safety.
Anand Parikh, Co-Founder and Chief Executive Officer of Faeth, outlined the company’s next step.
“We now plan to advance toward a Phase 3 trial, subject to regulatory alignment, with the goal of getting PIKTOR into the hands of patients as expeditiously as possible.”
For community oncologists, the immediate relevance is to trial discussions for patients with pathway-altered endometrioid disease after prior taxane and immunotherapy exposure. For investigators, the 7-of-16 response finding warrants prospective evaluation of PIK3CA as a potential predictor of benefit, alongside a fuller assessment of severe toxicity and treatment burden.
You can also read: TroFuse-005 at ESMO 2026: Sacituzumab Tirumotecan Significantly Improves Overall Survival in Advanced Endometrial Cancer.
