First-in-human phase I/II study of CYT-0851, a first-in-class inhibitor of RAD51-mediated homologous recombination in patients with advanced solid and hematologic cancers

3006

Background: Homologous recombination (HR) is an essential, high-fidelity mechanism to repair DNA double strand breaks (DSBs). Inhibition of HR in cancer cells leads to accumulation of unrepaired DSBs and tumor cell death. This is the first reporting of the first-in-human study of CYT-0851, an oral, first-in-class, small molecule inhibitor of RAD51-mediated DNA repair. Methods: Patients (pts) with advanced hematologic and solid tumors were treated with continuous 28-day cycles of increasing doses of CYT-0851 with an accelerated titration and 3+3 trial design. Primary objectives included safety, maximum tolerated dose (MTD), recommended Phase 2 dose (RP2D) (Phase 1), and antitumor activity (Phase 2). Secondary and exploratory objectives included pharmacokinetics (PK), pharmacodynamics (PD) and predictive biomarkers of response. Results: As of an 8 Dec 2020 data cutoff (DCO), 23 pts with advanced cancers (Sarcoma n = 8, Breast n = 4, Non-Hodgkin’s Lymphoma n = 5; Pancreas n = 3; Ovarian n = 2; mucoepidermoid carcinoma n = 1) were enrolled in 6 cohorts (15 mg, 20 mg, 30 mg, and 45 mg BID; 90 mg and 130 mg QD). No pts experienced a dose-limiting toxicity and escalation continues per protocol to identify the MTD. 6 pts (26.1%) experienced a CYT-0851-related adverse event with only Gr 1/2 nausea (n = 3, 13%) and constipation (n = 2, 8.7%) occurring in > 1 pt. There has been no reported CYT-0851-related myelosuppression, serious adverse events, study discontinuation, or death. Preliminary PK analyses showed dose proportional systemic exposure with a half-life of ̃3 days supporting transition from BID to QD dosing. PD effects were observed with increases in ɣH2AX in on-treatment circulating tumor cells compared to baseline at exposures associated with preclinical anti-tumor activity. Ten pts were response evaluable prior to the DCO. Two partial responses by Lugano and RECIST v1.1 criterion were achieved in pts with DLBCL (-74%) and myxofibrosarcoma (-30%) at 45 mg BID with treatment ongoing at 126+ and 250+ days. An additional two pts, with pancreatic cancer (-19%) and follicular lymphoma (-42%) had stable disease with tumor shrinkage at 45 mg BID for 111 and 99+ days. Conclusions: CYT-0851, a first-in-class inhibitor of RAD51-mediated HR, is well tolerated, with linear PK, target-directed PD effects and promising antitumor activity across different tumor types. CYT-0851 is the first DNA-damage repair (DDR) therapeutic with demonstrated clinical activity in both hematologic malignancies and solid tumors. Dose escalation continues to establish the RP2D, with planned expansion in 7 disease-specific cohorts in hematologic and solid cancers. Clinical trial information: NCT03997968.

Talimogene Laherparepvec Improves Durable Response Rate in Patients With Advanced Melanoma

Purpose

Talimogene laherparepvec (T-VEC) is a herpes simplex virus type 1–derived oncolytic immunotherapy designed to selectively replicate within tumors and produce granulocyte macrophage colony-stimulating factor (GM-CSF) to enhance systemic antitumor immune responses. T-VEC was compared with GM-CSF in patients with unresected stage IIIB to IV melanoma in a randomized open-label phase III trial.

Patients and Methods

Patients with injectable melanoma that was not surgically resectable were randomly assigned at a two-to-one ratio to intralesional T-VEC or subcutaneous GM-CSF. The primary end point was durable response rate (DRR; objective response lasting continuously ≥ 6 months) per independent assessment. Key secondary end points included overall survival (OS) and overall response rate.

Results

Among 436 patients randomly assigned, DRR was significantly higher with T-VEC (16.3%; 95% CI, 12.1% to 20.5%) than GM-CSF (2.1%; 95% CI, 0% to 4.5%]; odds ratio, 8.9; P < .001). Overall response rate was also higher in the T-VEC arm (26.4%; 95% CI, 21.4% to 31.5% v 5.7%; 95% CI, 1.9% to 9.5%). Median OS was 23.3 months (95% CI, 19.5 to 29.6 months) with T-VEC and 18.9 months (95% CI, 16.0 to 23.7 months) with GM-CSF (hazard ratio, 0.79; 95% CI, 0.62 to 1.00; P = .051). T-VEC efficacy was most pronounced in patients with stage IIIB, IIIC, or IVM1a disease and in patients with treatment-naive disease. The most common adverse events (AEs) with T-VEC were fatigue, chills, and pyrexia. The only grade 3 or 4 AE occurring in ≥ 2% of T-VEC–treated patients was cellulitis (2.1%). No fatal treatment-related AEs occurred.

Conclusion

T-VEC is the first oncolytic immunotherapy to demonstrate therapeutic benefit against melanoma in a phase III clinical trial. T-VEC was well tolerated and resulted in a higher DRR (P < .001) and longer median OS (P = .051), particularly in untreated patients or those with stage IIIB, IIIC, or IVM1a disease. T-VEC represents a novel potential therapy for patients with metastatic melanoma.

OPTiM: A randomized phase III trial of talimogene laherparepvec (T-VEC) versus subcutaneous (SC) granulocyte-macrophage colony-stimulating factor (GM-CSF) for the treatment (tx) of unresected stage IIIB/C and IV melanoma

LBA9008

Background: T-VEC is an oncolytic immunotherapy (OI) derived from herpes simplex virus type-1 designed to selectively replicate within tumors and to produce GM-CSF to enhance systemic antitumor immune responses. OPTiM is a randomized, phase III trial of T-VEC or GM-CSF in patients (pts) with unresected melanoma with regional or distant metastases. We report the primary results of the first phase III study of OI. Methods: Key criteria: age ≥18 yrs; ECOG ≤1; unresectable melanoma stage IIIB/C or IV; injectable cutaneous, SC, or nodal lesions; LDH ≤1.5X upper limit of normal; ≤3 visceral lesions (excluding lung), none >3 cm. Pts were randomized 2:1 to intralesional T-VEC (initially ≤ 4 mL x106 pfu/mL then after 3 wks, ≤ 4 mL x108 pfu/mL Q2W) or SC GM-CSF (125 µg/m2qd x 14 days q28d). The primary endpoint was durable response rate (DRR): partial or complete response (CR) continuously for ≥6 mos starting within 12 mos. Responses were per modified WHO by blinded central review. A planned interim analysis of overall survival (OS; key secondary endpoint) was performed. Results: 436 pts are in the ITT set: 295 (68%) T-VEC, 141 (32%) GM-CSF. 57% were men; median age was 63 yrs. Stage distribution was: IIIB/C 30%, IVM1a 27%, IVM1b 21%, IVM1c 22%. Objective response rate with T-VEC was 26% (95% CI: 21%, 32%) with 11% CR, and with GM-CSF was 6% (95% CI: 2%, 10%) with 1% CR. DRR for T-VEC was 16% (95% CI: 12%, 21%) and 2% for GM-CSF (95% CI: 0%, 5%), p<0.0001. DRR by stage (T-VEC, GM-CSF) was IIIB/C (33%, 0%), M1a (16%, 2%), M1b (3%, 4%), and M1c (8%, 3%). Interim OS showed a trend in favor of T-VEC; HR 0.79 (95% CI: 0.61, 1.02). Most common adverse events (AEs) with T-VEC were fatigue, chills, and pyrexia. Serious AEs occurred in 26% of T-VEC and 13% of GM-CSF pts. No ≥ grade 3 AE occurred in ≥ 3% of pts in either arm. Conclusions: T-VEC demonstrated both a statistically significant improvement in DRR over GM-CSF in pts with unresectable stage IIIB-IV melanoma and a tolerable safety profile; an interim analysis showed a trend toward improved OS. T-VEC represents a novel potential tx option for melanoma with regional or distant metastases. Clinical trial information: NCT00769704.

OPTiM: A randomized phase III trial of talimogene laherparepvec (T-VEC) versus subcutaneous (SC) granulocyte-macrophage colony-stimulating factor (GM-CSF) for the treatment (tx) of unresected stage IIIB/C and IV melanoma

LBA9008

The full, final text of this abstract will be available at abstract.asco.org at 7:30 AM (EDT) on Saturday, June, 1, 2013, and in the Annual Meeting Proceedings online supplement to the June 20, 2013, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Saturday edition of ASCO Daily News.