*Article* **Preliminary Exploration of a New Therapy for Interstitial Cystitis/Bladder Pain Syndrome: Botulinum Toxin A Combined with Sapylin**

**Wenshuang Li 1,2,3,4,†, Zhenming Zheng 1,2,3,†, Kaiqun Ma 1,2,3,5,†, Caixia Zhang 1,2,3, Kuiqing Li 1,2,3, Paierhati Tayier 1,2,3 and Yousheng Yao 1,2,3,\***


**Abstract:** Interstitial cystitis/bladder pain syndrome (IC/BPS) is an intractable disease without long-term effective therapy. This study aims to evaluate the efficacy and safety of botulinum toxin A (BoNT/A) plus Sapylin, which might modulate the immune response of the bladder in the treatment of IC/BPS patients. We retrospectively investigated the clinical outcomes among 34 patients who accepted repeated Sapylin instillations after 200 U of BoNT/A submucosally injected into bladder walls (Mix group) and 28 patients who received BoNT/A alone (Control group). Each of the bladder walls (left, right, anterior and posterior) was injected six times with 8 U of BoNT/A per injection. The primary outcome measure was the global response assessment. The results showed that at 6 months post-injection, the response rate in the Mix group was remarkably higher than that in the Control group (58.8% vs. 28.6%, *p* < 0.05). The mean effective duration of the responders in the Mix group was apparently better than that in the Control group (27.5 (range 0–89) vs. 4.9 (range 0–11) months, *p* < 0.05). None of the patients experienced serious adverse events. In conclusion, repeated intravesical instillations of Sapylin after BoNT/A injection can produce significantly better clinical outcomes than BoNT/A alone in IC/PBS patients.

**Keywords:** bladder pain syndrome; botulinum toxin A; interstitial cystitis; Sapylin

**Key Contribution:** This is the first study to apply BoNT/A plus Sapylin to treat IC/BPS; this can produce significantly better clinical outcomes than BoNT/A alone.
