Phase II Study Of Anti-CD19 Antibody Drug Conjugate (SAR3419) In Combination With Rituximab: Clinical Activity and Safety In Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma (NCT01470456)

SAR3419 is a humanized anti-CD19 antibody conjugated to maytansin DM4, a potent cytotoxic agent. SAR3419 targets CD19, an antigen expressed in the majority of B cell non-Hodgkin lymphomas (NHL). The recommended dose for single agent SAR3419 was previously determined to be 55 mg/m² administered IV every week for 4 weeks, then bi-weekly. In phase I, clinical activity was shown mainly in patients with follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL). (Trial funded by Sanofi).

Patients (pts) with a CD20+ and CD19+ DLBCL relapsing or refractory (R/R) after at least 1 standard treatment including rituximab and not candidate for or who already underwent transplantation, were eligible. Refractory disease was defined as unresponsive to or progressing within 6 months of regimen completion. Fresh (or recent formalin-fixed, paraffin-embedded) biopsy was required before SAR3419 start.

Pts received 375 mg/m² of rituximab (R) IV and 55 mg/m² of SAR3419 on day 1, 8, 15, 22 (35-day cycle 1), followed by bi-weekly R and SAR3419 at the same doses for 2 additional 28-day cycles, provided there was no disease progression or other study discontinuation criteria met. The primary objective was the overall response rate (ORR) following Cheson 2007 criteria, with the first tumor assessment being done 42 days after the last study treatment administration. Secondary objectives were: safety, pharmacokinetics (PK), duration of response (DOR), progression free survival (PFS), overall survival (OS) and correlation of the antitumor and biological activity of the combination with tumor biomarker status.

Fifty-three pts were enrolled, 52 treated. Median age was 66.5 years (range 38-85), 50% were male; 23%, 33% and 40% of patients had received 1, 2 or ≥3 prior chemo/immunotherapy regimens for DLBCL, respectively. Of the enrolled patients, 3.8% had received no prior regimen for DLBCL and therefore were excluded from primary analysis for efficacy. Seventy-three percent had stage III/IV disease, 59% had elevated lactate dehydrogenase (LDH), and 63% had bulky disease. Sixty percent were refractory to first regimen (primary refractory), 16% were refractory to last regimen and 24% were relapsed pts. The ORR in the per-protocol population (n=45) was 31.1% (80% confidence interval (CI): 22.0% to 41.6%). Among the 14 responders, 5 had progressed at the time of analysis, with duration of response beyond 6 months for 3 of them. The ORR was 58.3% (80% CI: 36.2% to 78.1%) for patients with relapsed DLBCL (n=12), 42.9% (80% CI: 17.0% to 72.1%) for pts refractory to last regimen (n=7) and 15.4% (80% CI: 6.9% to 28.4%) for primary refractory pts (n=26). Overall survival and PFS data are not yet mature. Biomarkers and PK data will be presented at the meeting.

The most common (≥10%) all grades non-hematologic treatment-emergent adverse events (TEAEs) were asthenia (25.0%), nausea (21.2%), cough (19.2%), diarrhea (17.3%), weight decrease (17.3%), vomiting (15.4%), dyspnea (15.4%), abdominal pain (13.5%), back pain (13.5%), pyrexia (13.5%) and constipation (11.5%). Related grade 3-4 TEAEs were: 1 syncope, 1 bronchospasm, 2 neutropenia and 1 anemia. No TEAEs led to treatment discontinuation, no grade 3-4 peripheral neuropathy or grade 3-4 ocular events were observed. Two pts experienced grade 2 keratitis, both rapidly recovered with local treatment. Hematological toxicity was moderate, with grade 3-4 neutropenia and thrombocytopenia in 15.7% and 9.8% pts, respectively. No complications related to neutropenia were reported. Grade 3 transaminase increase was observed in 1 patient.

The combination of SAR3419 plus R showed moderate ORR in R/R DLBCL; however the study population was of poor prognosis (60% refractory to first line therapy). In the relapsed DLBCL patients a higher ORR was observed. SAR3419 plus R presented with a favorable safety profile. Further investigations on biomarker expression are ongoing to identify a sub-group of pts who could have better benefited from this combination.

Coiffier:Sanofi: Membership on an entity’s Board of Directors or advisory committees. Off Label Use: Phase II of SAR3419. Ribrag:Johnson & Johnson: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Sanofi: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Bayer: Research Funding; Takeda: Membership on an entity’s Board of Directors or advisory committees; Servier: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Cartron:LFB: Honoraria; GSK: Honoraria; Roche: Consultancy, Honoraria, Speakers Bureau. Casasnovas:Roche: Consultancy, Honoraria, Research Funding. Hatteville:Sanofi: Employment. Zilocchi:Sanofi: Employment. Oprea:Sanofi: Employment. Tilly:Amgen: Research Funding; Janssen: Honoraria; Pfizer: Honoraria; Takeda: Membership on an entity’s Board of Directors or advisory committees; Roche: Honoraria; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding.