Clinical efficacy of Nocardia rubra cell wall skeleton (Nr-CWS) immunotherapy for high-grade squamous intraepithelial lesions: a complementary fertility-preserving treatment option for selected patients

High-grade squamous intraepithelial lesions (HSIL) with persistent high-risk human papillomavirus (HR-HPV) infection require treatment to prevent cervical cancer progression. Surgical excision is effective but associated with adverse obstetric outcomes. Nocardia rubra cell wall skeleton (Nr-CWS) immunotherapy offers a non-surgical alternative for selected patients with specific indications. To evaluate Nr-CWS efficacy in HPV clearance and histopathological lesion regression, identify optimal patient selection criteria, and assess pregnancy outcomes in women with fertility desires. This single-centre retrospective cohort study included 262 patients with histologically confirmed HSIL and persistent HR-HPV treated with Nr-CWS (2017–2025), selected on stringent colposcopic and pathological criteria, and 459 surgical controls (women aged <40 years with biopsy-confirmed CIN2 treated by LEEP or CKC during the same period). Inclusion criteria required completely visible transformation zone, focal lesions with visible margins, negative endocervical curettage, and either a strong fertility-preservation desire or refusal of, or contraindication to, excision. The primary outcomes were complete HR-HPV clearance and complete histological regression; partial (type-specific) HPV clearance and residual CIN1/LSIL were recorded separately as secondary descriptive outcomes. Follow-up assessments (TCT, HPV, colposcopy with biopsy) were performed 2–3 months after Nr-CWS treatment completion and 3–6 months post-surgery. Among 223 evaluable Nr-CWS patients, complete HR-HPV clearance was achieved in 57.4% (128/223; 95% CI 50.8–63.7), compared with 82.2% (277/337; 95% CI 77.8–85.9) in the surgical cohort, a difference of − 24.8 percentage points (95% CI − 32.5 to − 17.1; p<0.001). Partial (type-specific) clearance occurred in a further 33.2% (74/223) after Nr-CWS and is reported separately rather than as treatment success. Histopathological assessment in 198 HSIL patients showed complete regression (normal/inflammation, no residual CIN) in 62.1% (95% CI 55.2–68.6); residual CIN1/LSIL, which was not counted as treatment success, was present in 30.8%, a high-grade lesion persisted in 5.6%, and CIN3 was identified at follow-up in 1.5%. Lesion extent did not influence the response: complete clearance was 56.6% in women with one or two involved clock positions and 57.1% in those with three or more (p=1.000). Subgroup analysis by pathology grade, CIN2 patients ( n = 172 evaluable) achieved 90.7% effectiveness; CIN3 patients ( n = 51 evaluable) achieved 90.2% (95% CI 79.0–95.7), an estimate too imprecise to support any conclusion about CIN3. Among 33 pregnancies in the Nr-CWS group, 87.9% occurred in women ≤35 years. Observed pregnancies (33 vs. 28; the number of women attempting conception was not recorded) ended in full-term delivery in 81.8% (95% CI 65.6–91.4) and 75.0% (95% CI 56.6–87.3) respectively (p=0.547). Nr-CWS does not replace surgical treatment but provides a complementary fertility-preserving option for patients meeting specific criteria: completely visible transformation zone, focal lesions with visible margins, negative endocervical curettage, and strong fertility preservation desire. CIN2 diagnosed on colposcopy-directed biopsy is the principal indication, with the caveat that punch biopsy under-estimates lesion grade in a substantial minority of women; the present data cannot establish efficacy in CIN3, for which excision remains the standard of care. The comparison with the surgical cohort is observational and does not establish equivalence between Nr-CWS and excisional treatment.