Safety and efficacy results from the expansion phase of the first-in-human study evaluating TGFβ inhibitor SAR439459 alone and combined with cemiplimab in adults with advanced solid tumors

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Background: SAR439459 (SAR459) is a human anti-TGFβ monoclonal antibody that neutralizes all isoforms of TGFβ. In preclinical models, combining SAR459 with an anti-PD-1 showed improved anti-tumor activity compared to SAR459 single agent. In the dose escalation, acceptable tolerability was observed, the MTD was not reached and the preliminary RP2D was 22.5mg/kg Q3W when combined with cemiplimab (CEMI; S. Williamson et al. J Clin Oncol 39, 2021[suppl 15; #2510]). Reduction of plasma TGFβ was ≥90% at doses ≥0.25mg/kg Q2W, with a trend of a decrease in intra-tumoral TGFβ (D. Robbrecht et al. JITC 2021;9 [suppl 2; #250]). Here we report safety and efficacy results of the dose expansion. Methods: The expansion phase of this open-label, phase 1/1b study aimed to determine the optimal dose of SAR459 (7.5 mg/kg or 22.5 mg/kg Q3W) in patients (pts) with advanced melanoma (MEL) resistant to anti-PD(L)1 therapy (Part 2A); and the ORR (confirmed responses) in all treated pts with SAR459 22.5 mg/kg + CEMI 350 mg Q3W in pts with MEL, Non-small Cell Lung Cancer (NSCLC), or Hepatocellular Carcinoma (HCC), resistant to anti-PD(L)1; as well as in pts with mesenchymal Colorectal Cancer (CRC) or Urothelial Cancer (UC), anti-PD(L)1 naïve (Part 2B). Results: From October 2019 to September 2021, 109 pts with ECOG PS 0-1 enrolled in Part 2A (14) and Part 2B (95). Overall, the median age was 63 years and 83% of pts received up to 3 prior treatment lines for advanced disease (range 1-8). Based on preliminary data, the ORR in Part 2B was 8% (Table). No significant association between clinical response and plasma TGFb level at baseline or modulation upon treatment was observed. The correlation between tumor TGFb level and clinical benefit is inconclusive due to limited number of tumor biopsies. No response was observed in Part 2A. Overall, 100% of pts had at least one treatment emergent adverse event (AE), 67% were G≥3, 34% related G≥3, 17% G5, and 4% related G5. The limited number of patients treated with SAR459 alone at the RP2D did not allow to demonstrate added toxicity due to the combination. Overall, 51 pts (47%) reported hemorrhagic AE of any grade, 8 pts (7%) had G≥3 and 5 pts (5%) had fatal outcome. The rate of bleeding and severe hemorrhagic AE was higher in HCC pts compared to the other cohorts: 11/14 (79%) pts had a hemorrhagic AE, of which 3 (21%) G≥3 and fatal. An exploratory analysis showed a trend for higher frequency of any grade SAR459-related and fatal hemorrhagic AE in patients with higher exposure. Conclusions: The NCT03192345 study was discontinued due to a lack of efficacy, and a high bleeding risk particularly in pts with HCC. Clinical trial information: NCT03192345. [Table: see text]

A phase 1/2 trial of lurbinectedin (L) in combination with pembrolizumab (P) in relapsed small cell lung cancer (SCLC): The LUPER study

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Background: L is a novel anticancer agent that inhibits trans-activated transcription and modulates the tumor microenvironment. L is approved by the FDA for metastatic SCLC patients (pts) with progressive disease (PD) on or after platinum-based chemotherapy (CT). The LUPER study is assessing the safety, tolerability, and preliminary efficacy of L+P as second-line regimen for SCLC pts after failure of platinum-based CT. Phase 1 data are presented here. Methods: In this phase 1/2 trial (NCT04358237), adult pts with histologically confirmed SCLC, PD to a previous CT-containing regimen (≥4 weeks before study initiation), no prior exposure to immunotherapy, ECOG PS of 0-1, and measurable disease as per RECIST 1.1 are eligible. Pts with treated, stable, and asymptomatic brain metastases (BMs) are allowed. A 3+3 dose-escalation was done to determine the recommended phase 2 dose (RP2D) of L+P. L was dosed at 2.4 mg/m2 and 3.2 mg/m2 IV Q3W in the dose level (DL)1 and 2, respectively, in combination with fixed dose of P (200 mg IV Q3W). The RP2D was the highest DL at which 0/3 pts or ≤1/6 pts experienced dose-limiting toxicities (DLTs) during the first cycle. Treatment was administered until PD, unacceptable toxicity, or consent withdrawal. Secondary endpoints include safety as per CTCAE 5.0, preliminary efficacy, and pharmacokinetics. Results: Thirteen pts were enrolled across 3 hospitals in Spain (DL1, n = 7; DL2, n = 6). Median age was 66 (range 43–78) years, 46.2% were female, 61.5% had ECOG PS of 1, 38.5% had platinum-free interval < 90 days, 30.8% had LDH > upper normal limit, and 15.4% had BMs. One DLT (G3 asthenia) and one G4 neutropenia lasting > 3 days (controlled with G-CSF prophylaxis upon C2, without requiring dose delay or modification) occurred in the DL1. No DLT were reported in the DL2. The RP2D was identified as 3.2 mg/m2 L and 200 mg P IV Q3W. At data cutoff (Jan 21, 2022), 5 (38.4%) pts remained on treatment (1 pt in DL1 discontinued due to COVID-19 in cycle 1). Median duration of treatment was 2.1 (0–11.8) months, 5 (38.5%) pts had ≥8 cycles, and median relative dose intensity of L and P were 91.1% and 95.7%, respectively. Immune-related AEs (G2 pneumonitis; G3 ALT increased) led to P discontinuation in 2 (15.4%) pts. Responses were shown in both DLs, with ORR of 30.8% (1 confirmed complete response and 3 partial responses); 3 pts had stable disease (SD; including 1 patient with SD > 12 weeks) and 5 (38.5%) pts experienced PD. Conclusions: This is the first report to demonstrate a manageable safety profile and preliminary efficacy of second-line L+P for relapsed SCLC pts. This combination warrants further confirmation in the ongoing expansion phase 2. Clinical trial information: NCT04358237.

A phase 1b/2 study of the BET inhibitor ZEN-3694 in combination with talazoparib for treatment of patients with TNBC without gBRCA1/2 mutations

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Background: Metastatic triple negative breast cancer (mTNBC) is an aggressive and heterogeneous cancer with limited therapeutic options. PARP inhibitors (PARPi), approved to treat patients with HER2- breast cancer with a germline BRCA1/2 (gBRCA1/2) mutation, have not shown efficacy in homologous recombination repair (HRR) proficient tumors. In pre-clinical models, the BET inhibitor (BETi) ZEN-3694 sensitizes wild-type (WT) BRCA1/2 tumors to PARPi through downregulation of HRR gene expression, providing a rationale for combination therapy. We previously reported results from the Ph 1b portion of the trial evaluating the combination of ZEN-3694 plus talazoparib, in TNBC patients without gBRCA1/2 mutations; here we present results from the completed Ph 1b/2 study. Methods: A Ph 1b dose finding portion (n = 15) was followed by a single arm Ph 2 Simon 2-stage portion (n = 17+20 (37)). The primary endpoint of the Ph 1b portion of the study was safety and recommended Ph 2 dose (RP2D). The secondary endpoints were pharmacokinetics (PK), pharmacodynamics (PD), and clinical benefit rate (CBR = confirmed objective response rate (ORR) + stable disease > 16 weeks). Ph 2 measured CBR as the primary endpoint, ORR and duration of response (DOR) as key secondary endpoints. Eligibility criteria for Ph 1b included TNBC (ER/PR < 10%, HER2-), WT gBRCA1/2, and > 1 prior cytotoxic regimen for mTNBC, and in the Ph2 portion ER/PR < 1% and < 2 prior cytotoxic regimens for mTNBC. Patients were dosed daily in continuous 28 day cycles until disease progression or unacceptable toxicity. Adverse events, PK, and PD in whole blood and tissue biopsies were assessed. Response endpoints were assessed per RECIST 1.1 every 2 cycles. Results: RP2D was determined to be 48mg qd ZEN-3694 plus 0.75mg qd talazoparib. The most common AE for the Ph 1b/2 study was thrombocytopenia (TCP) (55% any grade, 34% G3/4), which was managed with dose holds and reductions. Dose intensity analysis showed average daily doses of ZEN-3694 and talazoparib could be maintained above 40mg and 0.5mg, respectively, over 8 cycles. Robust target engagement was demonstrated using BET-dependent and HRR transcripts assessed in paired tumor biopsies. Ph 2 portion of the trial met its primary endpoint with a CBR of 30% (11/37). For the Ph 1b/2 trial, investgator assessed ORR was 22% (11/50), including 2 CR, CBR was 35% (18/51) and the median DOR was 24 weeks. For the subset of TNBC at diagnosis patients (no history of HR+ disease), ORR was 32% (11/34), and CBR was 44% (15/34). Conclusions: Combination of ZEN-3694 and talazoparib demonstrated anti-cancer activity in pretreated mTNBC WT gBRCA1/2 patients. All confirmed responses were observed in TNBC at diagnosis patients, whose tumors are expected to be more sensitive to the combination due to their basal-like properties. The trial is being expanded to Ph. 2b to accrue an additional 80 TNBC at diagnosis patients. Clinical trial information: NCT03901469.

Promising clinical benefit rates in advanced cancers alongside potential biomarker correlation in a phase I/II trial investigating bexmarilimab, a novel macrophage-guided immunotherapy

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Background: Clever-1 is an immunosuppressive scavenger receptor expressed on tumor associated macrophages. High levels of Clever-1 are associated with poor survival and immunotherapy resistance. Bexmarilimab (FP-1305) is a novel humanized anti-CLEVER-1 IgG4-antibody capable of inducing a phenotypic M2 to M1 immune switch of tumor-associated macrophages. Methods: MATINS (Macrophage Antibody To INhibit immune Suppression) trial is a first-in-human phase I/II study (NCT03733990) to assess safety and preliminary efficacy of Bexmarilimab in patients with refractory advanced solid tumours. Part I has been completed with initial good safety profile of the IMP, preliminary signs of efficiency, and recommended dose of 1mg/kg Q3W for part II (ESMO 2020). In Part II (ESMO 2021), 10 distinct solid tumour types were enrolled to assess preliminary efficacy (overall survival (OS), progression free survival (PFS), and clinical benefit rate (CBR). Clever-1 IHC in pre-treatment biopsies with Ventana platform using a primary antibody 4G9 (Santa Cruz) was scored by % of positive cells compared to the viable tumor cells. Results: At the Jan 2022, a total of 193 patients have been enrolled to the study. In the completed cohorts, 138 patients have received 1-21 doses (median 3) of Bexmarilimab Q3W. Bexmarilimab was well tolerated, and no new safety signals were detected. Part I and Part II fully enrolled 11 cancer cohorts, the median PFS was 2.0 months (95% CI 1.9 – 2.0) and the median OS was 5.2 months (95% CI 4.3 – 6.4). CBR for Part II was 17.3% (19/110) at cycle 4 of treatment (by RECIST v.1.1). Notably, 30-40% CBR at cycle 4 was seen in cutaneous melanoma (30%), gastric cancer (30%), cholangiocarcinoma (30%), hepatocellular cancer (40%), and ER+ breast cancer (40%). Six-month survival rates (landmark analysis) were 70.1% for CBR compared to 34.7% for non-CBR patients, with a similar duration of prior therapy in both groups. Preliminary biomarker analysis (n = 77) demonstrated positive trend (p = 0.038) between CBR and higher intratumoral Clever-1 positivity (median of 15% positivity (range 0-25) in CBR and 3% (range 0-85) in non-CBR patients) Conclusions: Bexmarilimab continues to demonstrate promising anti-tumour activity as a monotherapy in several refractory solid tumours. Furthermore, preliminary biomarker analysis suggests a possibility for patient selection based on tumour Clever-1 expression. Further expansion of the study will investigate optimal dosing and biomarkers of efficacy. Clinical trial information: NCT03733990.

Safety and Antitumor Activity of α-PD-L1 Antibody as Monotherapy or in Combination with α-TIM-3 Antibody in Patients with Microsatellite Instability-High/Mismatch Repair-Deficient Tumors

PURPOSE

Immune checkpoint inhibitors show high response rates and durable clinical benefit in microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) tumors. However, 50%-60% do not respond to single-agent anti-programmed death-1/programmed death ligand 1 (PD-1/PD-L1) antibodies, and approximately 50% of responders relapse within 6-12 months. This phase Ib trial evaluated safety and antitumor activity of anti-PD-L1 antibody LY3300054 monotherapy or in combination with anti-TIM-3 antibody LY3321367 in patients with MSI-H/dMMR advanced solid tumors.

PATIENTS AND METHODS

Eligible patients ≥18 years without prior anti-PD-1/PD-L1 therapy received LY3300054 monotherapy (N = 40) or combination (N = 20); patients with PD-1/PD-L1 inhibitor-resistant/refractory tumors received the combination (N = 22). LY3300054 (700 mg) and anti-TIM-3 antibody (cycles 1-2: 1,200 mg, cycle 3 onward: 600 mg) were administered intravenously every 2 weeks. Primary endpoints were safety and tolerability.

RESULTS

Eighty-two patients were enrolled. Most had colorectal (n = 39, 47.6%) or endometrial (n = 14, 17.1%) tumors. More than 70% of patients in the PD-1/PD-L1 inhibitor-resistant/refractory combination cohort had received ≥3 treatment lines. Treatment-related adverse events (TRAE) occurred in 22 patients (55.0%) receiving monotherapy, 13 (65.0%) in the PD-1/PD-L1 inhibitor-naïve combination cohort, and 6 (27.3%) in the PD-1/PD-L1 inhibitor-resistant/refractory combination cohort. A total of 2 patients (5.0%) receiving monotherapy and 3 (7.1%) receiving the combination experienced grade ≥3 TRAEs. Objective responses occurred in 13 patients (32.5%) with monotherapy, 9 (45.0%) in the PD-1/PD-L1 inhibitor-naïve combination cohort, and 1 patient (4.5%) in the PD-1/PD-L1 inhibitor-resistant/refractory combination cohort.

CONCLUSIONS

LY3300054 monotherapy and combined LY3300054/anti-TIM-3 had manageable safety profiles. Both regimens showed promising clinical activity against PD-1/PD-L1 inhibitor-naïve MSI-H/dMMR tumors. The combination had limited clinical benefit in patients with PD-1/PD-L1 inhibitor-resistant/refractory MSI-H/dMMR tumors.

Blocking TIM-3 in Treatment-refractory Advanced Solid Tumors: A Phase Ia/b Study of LY3321367 with or without an Anti-PD-L1 Antibody

PURPOSE

T-cell immunoglobulin and mucin-domain-containing molecule-3 (TIM-3) blunts anticancer immunity and mediates resistance to programmed death 1 (PD-1) and PD ligand 1 (PD-L1) inhibitors. We assessed a novel, first-in-class, TIM-3 mAb, LY3321367, alone or in combination with the anti-PD-L1 antibody, LY300054 in patients with advanced solid tumor.

PATIENTS AND METHODS

This open-label, multicenter, phase Ia/b study aimed to define the safety/tolerability and recommended phase II dose (RP2D) of LY3321367 with or without LY300054. Secondary objectives included pharmacokinetics/pharmacodynamics, immunogenicity, and efficacy. Biomarkers were assessed in exploratory analysis.

RESULTS

No dose-limiting toxicities were observed in the monotherapy (N = 30) or combination (N = 28) dose escalation. LY3321367 treatment-related adverse events (≥2 patients) included pruritus, rash, fatigue, anorexia, and infusion-related reactions. Dose-proportional increase in LY3321367 concentrations was not affected by either LY300054 or antidrug antibodies (observed in 50%-70% of patients). Pharmacokinetic/pharmacodynamic modeling indicated 100% target engagement at doses ≥600 mg. LY3321367 RP2D was 1,200 mg biweekly for four doses followed by 600 mg every 2 weeks thereafter. In the non-small cell lung cancer monotherapy expansion cohort, outcomes varied by prior anti-PD-1 therapy response status: anti-PD-1/L1 refractory patients [N = 23, objective response rate (ORR) 0%, disease control rate (DCR) 35%, progression-free survival (PFS) 1.9 months] versus anti-PD-1/L1 responders (N = 14, ORR 7%, DCR 50%, PFS 7.3 months). In combination expansion cohorts (N = 91), ORR and DCR were 4% and 42%; CD8 infiltration in paired biopsies increased in approximately half these patients.

CONCLUSIONS

LY3321367 exhibited acceptable safety profile with favorable pharmacokinetics/pharmacodynamics but only modest antitumor activity. The therapeutic relevance of TIM-3 blockade requires further investigation.

Safety and Clinical Activity of a New Anti-PD-L1 Antibody as Monotherapy or Combined with Targeted Therapy in Advanced Solid Tumors: The PACT Phase Ia/Ib Trial

PURPOSE

This phase Ia/Ib PACT study evaluated the safety, pharmacokinetics, pharmacodynamics, and antitumor activity of a new programmed cell death ligand 1 (PD-L1) inhibitor, LY3300054, as monotherapy or in combination with ramucirumab, abemaciclib, or merestinib (a type II MET kinase inhibitor) in patients with advanced, refractory solid tumors (NCT02791334).

PATIENTS AND METHODS

Patients were enrolled into cohorts of escalating LY3300054 dose (phase Ia) as monotherapy (N = 15) or combined with ramucirumab (N = 10), abemaciclib (N = 24), or merestinib (N = 12). The phase Ib dose expansion enrolled 8 patients with melanoma in the monotherapy arm and 12 patients with pancreatic cancer in the merestinib combination arm. Combination treatments were administered concurrently from day 1 of each cycle. A 14-day lead-in abemaciclib arm was also explored. Primary endpoints were dose-limiting toxicity (DLT) and safety.

RESULTS

Treatment-related adverse events included fatigue and nausea in the monotherapy arm (13% for each), hypothyroidism (30%) in the ramucirumab arm, diarrhea (54%) in the abemaciclib arm, and nausea (25%) in the merestinib arm. DLTs associated with hepatoxicity were observed in 3 of 4 patients in the abemaciclib lead-in cohorts. No DLTs or grade 3 or 4 hepatoxicity were reported in the concurrent abemaciclib arm. Pharmacokinetic characteristics were comparable with other PD-L1 inhibitors. One patient in each arm experienced a partial response per RECIST v1.1 lasting ≥7 months.

CONCLUSIONS

LY3300054 was well tolerated without unexpected safety concerns when administered alone or concurrently with ramucirumab, abemaciclib, or merestinib. Lead-in abemaciclib before combining with LY3300054 was not feasible due to hepatotoxicity. Durable clinical benefits were seen in all regimens.