Abstract CT177: A multi-center phase 2a trial of the CXCR4 inhibitor motixafortide (BL-8040) (M) in combination with pembrolizumab (P) and chemotherapy (C), in patients with metastatic pancreatic adenocarcinoma (mPDAC)

Background: Improving outcomes of PDAC with checkpoint inhibitors (CPIs) have been ineffective, underscoring the need to co-target alternative pathways. Preclinical data showed that CXCR4-SDF1 axis modulates the tumor microenvironment (TME) in PDAC and that CXCR4 inhibition enhances T cell access to the TME, increasing tumor sensitivity to CPIs. This was confirmed in the COMBAT Cohort 1 (CC1) study showing that the dual combination M+P increases activated CD8+ T cells and decreases myeloid derived suppressor cells (MDSCs) within the TME. Moreover, our pre-clinical studies showed that adding C to M+P resulted in improved efficacy vs C alone. The COMBAT Cohort 2 (CC2) aims to test the safety and efficacy of the triple combination of M+P+C in 2L mPDAC. Methods: Single arm phase 2a study in mPDAC. In cohort 2, patients with stage IV PDAC at diagnose who had progressed to 1L gemcitabine-based C received 5 days M priming, followed by M BIW + P Q3W plus C [Irinotecan liposomal injection/5-FU/LV (OFL)] Q2W. The primary endpoint was RR. Results: A total of 43 patients with stage 4 PDAC, 98% of whom were diagnosed with stage 4 disease, were enrolled. Median age was 68 (40-85) and 74.4% had liver disease. The safety profile was consistent with the individual profiles of each treatment alone. Of note, the incidence of ≥G3 neutropenia (G3Neu) was 7% and ≥G3 infection was 7%, which is lower than expected for C (OFL) alone (20% and 17%, respectively). The levels of T-cells increased during M priming and returned to normal values, which remained stable across the study despite the OFL treatment. For the evaluable patients (N=38) the ORR was 21.1% with a 13.2% confirmed ORR (defined as two consecutive assessments showing PR) and a 63.2% DCR (PR+SD). Median duration of clinical benefit was 5.6 months. Median OS and PFS were 6.5 months and 4.0 months, respectively (6.6 months and 3.8 months, respectively, for the ITT population). Conclusions: The triple combination of M+P+C is tolerable and shows encouraging results with cORR 13.2%, mPFS 4.0 months and mOS 6.5 months (compared to 7.7%, ~3 months and 4.7 months, respectively, on a historical basis for OFL alone in the stage 4 diagnosis subpopulation). SD of 42.1% and DCR of 63.2% were also higher than historical data on SoC chemotherapy used in 2L patients. The incidence of severe neutropenia and infections is lower than the historical data on C. The results from the CC2 suggest that M+P may expand the efficacy and safety benefit of OFL in PDAC, and warrants further investigation in a randomized study.

Citation Format: Manuel Hidalgo, Teresa Macarulla, Valerya Semenisty, Erkut Borazanci, Jaime Feliu, Mariano Ponz-Sarvise, David Gutierrez Abad, Paul Oberstein, Angela Alistar, Andres Muñoz, Ravit Geva, Carmen Guillén-Ponce, Mercedes Salgado Fernandez, Amnon Peled, Marya Chaney, Irit Glicko-Kabir, Liron Shemesh-Darvish, Debby Ickowicz, Ella Sorani, Shaul E. Kadosh, Abi Vainstein-Haras, Bruno Bockorny. A multi-center phase 2a trial of the CXCR4 inhibitor motixafortide (BL-8040) (M) in combination with pembrolizumab (P) and chemotherapy (C), in patients with metastatic pancreatic adenocarcinoma (mPDAC) [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 CT177.

BL-8040 CXCR4 antagonist is safe and demonstrates antileukemic activity in combination with cytarabine for the treatment of relapsed/refractory acute myelogenous leukemia: An open-label safety and efficacy phase 2a study

BACKGROUND

CXCR4 mediates the retention and survival of acute myelogenous leukemia blasts in bone marrow and contributes to their resistance to chemotherapy. The authors evaluated a combination of the high-affinity CXCR4 antagonist BL-8040 with high-dose cytarabine (HiDAC) chemotherapy in a phase 2a study of patients with relapsed and refractory AML.

METHODS

Forty-two patients received treatment with BL-8040 monotherapy for 2 days followed by a combination of BL-8040 with HiDAC for 5 days. Six escalating BL-8040 dose levels were investigated (0.5, 0.75, 1.0, 1.25, 1.5, and 2.0 mg/kg), and 1.5 mg/kg was selected as the dose for the expansion phase (n = 23).

RESULTS

BL-8040 in combination with HiDAC was safe and well tolerated at all dose levels. Clinical response was observed with BL-8040 doses ≥1.0 mg/kg. The composite response rate (complete remissions plus complete remissions with incomplete hematologic recovery of platelets or neutrophils) was 29% (12 of 42) in all patients and 39% (9 of 23) in the 1.5-mg/kg phase. The median overall survival was 8.4 months for all patients, 10.8 months in the 1.5-mg/kg phase, and 21.8 months for responding patients in the 1.5-mg/kg cohort. Two days of BL-8040 monotherapy triggered the mobilization of blasts into peripheral blood, with significantly higher mean fold-changes in responders versus nonresponders. This was accompanied by a decrease in bone marrow blasts.

CONCLUSIONS

The current results demonstrate the efficacy of CXCR4 targeting with BL-8040 and support continued clinical development in acute myelogenous leukemia.