Targeting inducible nitric oxide in a first-in-class phase 1/2 trial in triple-negative breast cancer patients diminishes M2 macrophage polarization and led to a robust clinical response. Andrew W. Chung*, Kartik Anand*, Polly Niravath* (co-first authors), Nakul Gupta, Luz A Venta, Mary R. Schwartz, Wei Qian, Yitian Xu, Licheng Zhang, Qiuying Chen, Nabeel Attarwala, John Kuhn, Tejal Patel, Angel Rodriguez, Anna Belcheva, Jorge Darcourt, Joe Ensor, Eric Bernicker, Ping-Ying Pan, Virginia Kaklamani, Shu Hsia Chen, Jenny C ChangIntroduction:The inducible nitric oxide signaling (iNOS) pathway has been associated with poor prognosis in triple-negative breast cancer (TNBC). Inhibition of iNOS pathway by using the pan-NOS inhibitor NG-monomethyl-L-arginine (L-NMMA) in patient-derived xenograft (PDX) models has shown reduced tumor growth and enhanced survival. Here, we report a first-in-class phase 1/2 trial of L-NMMA plus taxane for patients with chemorefractory locally advanced (LA) TNBC or metastatic TNBC and present findings on molecular immune correlates and metabolites of response/resistance. Methods:Women with chemorefractory LA or metastatic TNBC without uncontrollable hypertension or heart disease, age >18 years, and ECOG performance status ≤2 were eligible. A Bayesian model averaging continuous reassessment method was used to determine the recommended phase 2 L-NMMA dose (RP2D). In phase 1, two dose levels of docetaxel (75 and 100 mg/m2) and seven dose levels of L-NMMA (5,7.5, 10, 15,17.5, and 20 mg/kg) were studied. Patients in phase 2 received a maximum of six (q 3 weeks) cycles of L-NMMA given via IV on D1-D5. All patients also received amlodipine (6 days/cycle) and aspirin daily, as hypertensive and thromboembolic prophylaxis. Toxicity was measured as per CTCAE v4.03. Pharmacokinetics/Pharmacodynamics, 38 circulating cytokines, and 30 differential metabolites were also assayed. Tissue imaging mass cytometry (IMC) with 35 cell surface markers was performed on paired biopsies.

Results: From July 2016 to September 2020, a total of 35 patients were recruited (phase 1, n=15; phase 2, n= 24, including 4 RP2D patients from phase 1). RP2D dose was 20 mg/kg for L-NMMA and 100 mg/m2 for docetaxel. In phase 2, 54.2% had metastatic TNBC (with 5 median prior lines of chemotherapy) and 45.8% had LABC (anthracycline-refractory). Overall response rate (ORR) was 54.2% - 81.8% for LABC and 30.8% for metastatic TNBC. Radiologic complete response (CR) rate was 27.2% for LABC and 7.7% for metastatic TNBC. Among the LABC patients, 2 patients had pathological CR at surgery (18.2%). Grade ≥3 toxicity was noted in 21% of patients, however, none of grade ≥3 toxicity was attributed to L-NMMA. Compared to responder patients, correlative data showed that non-responders had a significant higher expression of biomarkers associated with M2 macrophage polarization including IL-10, adenosine and metabolite profile suggestive of aerobic glycolysis. In alignment, IMC analysis showed significant increase in intra-tumoral M2 macrophages in non-responders end of therapy biopsies.

Conclusion: L-NMMA combination with taxanes was well tolerated with a robust response rate. Further investigation is warranted to test this combination in larger studies along with biomarker evaluation.

Citation Format: Andrew W. Chung, Kartik Anand, Polly Niravath, Nakul Gupta, Luz A. Venta, Mary R. Schwartz, Wei Qian, Yitian Xu, Licheng Zhang, Qiuying Chen, Nabeel Attarwala, John Kuhn, Tejal A. Patel, Angel Rodriguez, Anna Belcheva, Jorge Darcourt, Joe E. Ensor, Eric Bernicker, Ping-Ying Pan, Virginia Kaklamani, Shu-Hsia Chen, Jenny C. Chang. Targeting inducible nitric oxide in a first-in-class phase 1/2 trial in triple-negative breast cancer patients diminishes M2 macrophage polarization and led to a robust clinical response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT175.