AUA 2024: SSANTROP (APRO07-2022): A Phase II Prospective, Open-Label, Multi-Center, Single Arm Study of Sasanlimab + Sacituzumab Govitecan in BCG-Unresponsive Non-Muscle Invasive Bladder Cancer Patients

( The 2024 American Urological Association (AUA) annual meeting featured a session on bladder cancer trials in progress, and a presentation by Dr. Oscar Rodriguez-Faba discussing SSANTROP (APRO07-2022), a phase II prospective, open-label, multi-center, single-arm study of sasanlimab + sacituzumab govitecan in BCG-unresponsive non-muscle invasive bladder cancer patients.

The primary objective of this trial is to evaluate the efficacy of sasanlimab + sacituzumab govitecan in combination by evaluating the complete response rate of high-risk disease at 3 months. This is defined as the absence of CIS, T1, high-grade Ta, or progressive disease. Sasanlimab is a humanized IgG4 monoclonal antibody directed against human PD-1, and sacituzumab govitecan is a Trop-2-directed antibody and topoisomerase inhibitor drug conjugate.

In this trial, patients will receive induction therapy of 7 cycles of sacituzumab govitecan (10 mg/kg IV) and 5 cycles of sasanlimab (300 mg SQ) over 20 weeks (sacituzumab govitecan first, then sasanlimab second) followed by a maintenance therapy regimen of 21 cycles of sasanlimab over 84 weeks. The trial design for SSANTROP is as follows:trial design for SSANTROP
Tumor evaluation will be with local cystoscopy, urine cytology, and directed biopsies if there are abnormal cystoscopy findings and random biopsies if there are abnormal cytology findings. Additionally, patients will receive an abdominal CTU every 24 weeks from the start of treatment. At the first tumor evaluation, if there is no complete response, the patient discontinues the study treatment.

Key inclusion criteria are:

  • Histological confirmed BCG-unresponsive high-risk nonmuscle invasive urothelial carcinoma obtained via TURBT no later than 16 weeks prior to the screening visit
  • Refused or ineligible for radical cystectomy
  • Age >18 years, ECOG 0-1, with adequate organ function prior to cycle 1 day 1
  • No other malignancy
  • Willingness to avoid pregnancy or fathering children

Key exclusion criteria include:

  • Evidence of muscle-invasive, locally advanced, or metastatic urothelial carcinoma or concurrent upper tract urothelial carcinoma
  • Involvement of the prostatic urethra or invasive prostatic urothelial carcinoma
  • Any systemic or intravesical chemotherapy or immunotherapy from the time of most recent positive TURBT (confirming BCG unresponsive disease) to initiation of study intervention
  • Prior immunotherapy with an anti PD-1, anti PD-L1 or any anti-CTLA4 therapy
  • Prior treatment with immunostimulatory agents (ie. IL-15, INF)
  • Prior radiation to the bladder
  • The tumor has any percentage of neuroendocrine differentiation

The action plan for recruitment includes investigator meetings, newsletters to investigators every month, weekly contact by CRAs with sites, a new protocol that was submitted on November 24, 2023 (changes that will make enrollment easier), and new sites to be included if some sites are closed for not recruiting. The study has been open for 15 months, with 25 patients enrolled (of a planned 116), with 19 active sites.

Presented by: Oscar Rodriguez-Faba, PhD, Urologist, Fundacio Puigvert, Autonomous University of Barcelona, Barcelona, Spain

Written by: Zachary Klaassen, MD, MSc - Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2024 American Urological Association (AUA) Annual Meeting, San Antonio, TX, Fri, May 3 - Mon, May 6, 2024.
Related content: SSANTROP Trial: Evaluating Sacituzumab Govitecan and Sasanlimab for BCG-Unresponsive Bladder Cancer - Oscar Rodriguez-Faba