Overview

TSL2109 is a novel CDK4/6-DYRK2 dual-target inhibitor developed by Jiangsu Tasly Diyee Pharmaceutical Co., Ltd. for solid tumor treatment. Preclinical studies confirm its selective targeting of CDK4/6 and DYRK2, a eukaryotic CMGC family kinase.

In palbociclib-resistant cell lines, TSL2109 downregulates cell cycle-related proteins and DYRK2 pathway ribosomal synthesis regulators (RRS1, CDK2), and upregulates p53, thus exerting synergistic antitumor effects and overcoming resistance to enzalutamide and palbociclib.

As a small-molecule inhibitor with novel targets, structure and mechanism, TSL2109 blocks tumor cell cycle progression independently of hormonal signaling. Preclinical studies show it overcomes AR inhibitor resistance, meeting unmet needs for prostate cancer patients progressing after AR inhibitor therapy. It also reduces CDK2 activity and blocks CDK4/6 compensatory mechanisms, reversing resistance to CDK4/6 inhibitors, providing a new option for HR+/HER2- advanced breast cancer patients.

Participants Dose-Escalation Phase: Advanced solid tumor patients, prioritizing metastatic castration-resistant prostate cancer (mCRPC) and HR+/HER2- advanced breast cancer.

Dose-Expansion Phase:

Cohort A/C: mCRPC; Cohort B/D: HR+/HER2- advanced breast cancer. Treatment Regimens C0 Cycle (3 days): Single oral dose on Day 1 morning under fasting, followed by 72-hour observation.

C1 Cycle (28 days): Daily fasting oral dosing (QD) for 3 weeks, then 1-week rest. Participants may continue treatment if no DLT and potential clinical benefit.

Dose escalation to a pre-established tolerable level is allowed per investigator-sponsor agreement if well-tolerated and likely beneficial. Treatment continues until disease progression, intolerable toxicity or new antitumor therapy. The Dose-Expansion Phase uses the same regimen as C1.

Missed Dose: Make-up within 8 hours; skip if delayed over 8 hours. Notes: Once MTD is determined, participants dosed above MTD will be adjusted to MTD. All doses are administered orally under fasting conditions.

Eligibility

Inclusion Criteria:

1. Age ≥18 years.
2. Histologically or cytologically confirmed advanced solid tumors, with failure of prior standard therapy, or no available standard therapy, or currently unsuitable for standard therapy, and not amenable to surgery or radiotherapy with curative intent. Priority will be given to patients with metastatic castration-resistant prostate cancer (mCRPC) and HR+/HER2- advanced breast cancer.
3. (Dose-Escalation Phase) At least one evaluable or measurable tumor lesion per RECIST Version 1.1; (Dose-Expansion Phase) At least one measurable tumor lesion per RECIST Version 1.1 (tumor lesions located in prior radiation fields or other locally treated sites generally do not qualify as measurable lesions unless there is clear progression or persistence three months after radiotherapy).
4. Life expectancy ≥3 months.
5. ECOG performance status score of 0 to 1.

Metastatic Castration-Resistant Prostate Cancer (mCRPC):

Castration status at screening: (1) Currently receiving androgen deprivation therapy (ADT) with luteinizing hormone-releasing hormone (LHRH) agonist/antagonist or history of bilateral orchiectomy. (2) Serum total testosterone ≤1.7 nmol/L (50 ng/dL) at screening. Additionally, progression documented by one or more of the following three criteria: ① PSA progression defined as PSA \>1 ng/mL with two consecutive increases \>50% from baseline at least 1 week apart; ② Soft tissue disease progression per RECIST 1.1; ③ Bone disease progression per PCWG3, defined as two or more new bone lesions on bone scan. Priority will be given to end-line patients who have received prior androgen receptor inhibitors and have received chemotherapy or are chemotherapy-intolerant or chemotherapy-refusing.

HR+/HER2- Breast Cancer:

① Histologically or cytologically confirmed HR-positive, HER2-negative breast cancer (determined from the most recent tumor sample \[primary or metastatic\] with histological confirmation of HR+/HER2- status. To meet HR+ disease requirements, breast cancer must express estrogen receptor \[ER\], with or without progesterone receptor co-expression), locally advanced or recurrent/metastatic breast cancer in female patients. ② Prior exposure to CDK4/6 inhibitors (e.g., abemaciclib, palbociclib, etc.).

Exclusion Criteria:

1. Clinically symptomatic central nervous system (CNS) metastases or leptomeningeal metastases, or other evidence indicating uncontrolled CNS or leptomeningeal metastases, judged by the investigator as unsuitable for enrollment.
2. Diagnosis of another invasive malignancy within the past 2 years, except for radically treated non-melanomatous skin cancer or superficial urothelial carcinoma, cutaneous basal cell or squamous cell carcinoma, superficial bladder cancer, prostate carcinoma in situ, papillary thyroid carcinoma, cervical carcinoma in situ, or breast carcinoma in situ.
3. Clinically significant gastrointestinal dysfunction that may affect drug intake, transport, or absorption, such as inability to take oral medications, uncontrolled nausea or vomiting, history of extensive gastrointestinal resection, unresolved recurrent diarrhea, untreated gastric conditions requiring long-term proton pump inhibitor therapy, Crohn's disease, ulcerative colitis, intestinal obstruction, etc.
4. Imaging (CT or MRI) showing tumor invasion of major blood vessels (e.g., aorta, pulmonary arteries/veins, vena cava, etc.) with assessed bleeding risk.
5. Interstitial lung disease, pneumonitis, or pulmonary fibrosis, assessed by the investigator as unsuitable for enrollment.
6. History of deep vein thromboembolism.