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#755 Evaluating the combination of CDK 4/6 inhibitors and endocrine therapy in endometrial and ovarian cancers: a retrospective study
  1. Deandra Chetram,
  2. Grace Choong and
  3. Andrea Wahner Hendrickson
  1. Mayo Clinic, Rochester, Mn, USA


Introduction/Background CDK 4/6 inhibitors (CDK4/6i) with endocrine therapy (ET) has promising phase II results in oestrogen receptor (ER)+ recurrent/advanced endometrial cancer (EC) and low grade serous ovarian carcinoma (LGSOC). The purpose of this study is to evaluate characteristics and clinical outcomes of patients with ER+ EC or ovarian cancer (OC) who have received a CDK4/6i+ET at our institution.

Methodology This was a multi-site single centre institution retrospective chart review, including patients diagnosed with EC and OC treated with CDK4/6i+ET between 2016- March 2023 for ≥1 month. Variables obtained included histology, age, and prior ET. Outcomes evaluated included best radiographic response (BRR), time to treatment failure (TTF), and duration of response (DOR).

Results Thirteen patients with EC (8 endometrioid, 4 endometrial stromal sarcoma, 1 adenocarcinoma) and five OC patients were identified (4 LGSOC and 1 mixed low/high grade serous OC).

In EC patients, the TTF was 5.1 months (95% CI 3.8-NR) and 9.8 months (95% CI 7.9-NR) for the endometrioid and ESS group, respectively. EC patients who had CDK 4/6i (n=4) added to ET due to progression had a median DOR of 7.0 months (IQR 5.4–10.4 months), with BRR of stable disease (SD) for all four patients. For EC patients who started CDK4/6i+ET concurrently, their DOR was 11.7 months (IQR 7.7–24 months) with BRR of partial response (PR) (n=1), SD (n=2), and progressive disease (n=3). For OC, the TTF was 13.5 months (95% CI 5.4-not evaluable). All OC patients had CDK 4/6i added to their ET due to progression, with a median DOR on CDK4/6i+ET of 9.0 months (IQR 5.4–13.5 months).

Conclusion Although small sample sizes, this data supports combination therapy in ER+ low grade gynaecologic malignancies including those who have progressed on prior ET. The combination should also be further explored in ESS.

Disclosures Deandra Chetram, MD- No disclosures

Grace Choong, MD- Receipt of honoraria or consultation fees from Targeted Oncology, no other disclosures

Andrea Wahner Hendrickson, MD- Receipt of grants/research supports for Prolynx (clinical trial support) and advisory board for Oxcia (unpaid), otherwise, no other disclosures

This study was not funded by any parties.

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