Phase 2 study of the IDO/PD-L1-targeted immune-modulatory vaccine, IO102-IO103, plus pembrolizumab as first-line treatment for metastatic non–small cell lung cancer (NSCLC), squamous cell carcinoma of the head and neck (SCCHN), or urothelial bladder cancer (UBC)

TPS2699

Background: Immunotherapy has transformed the treatment of NSCLC and other solid tumors, such as SCCHN and UBC. However, even with standard-of-care anti-PD-1/PD-L1 therapies, few patients achieve durable benefit even when PD-L1 is overexpressed. IO102-IO103 is a potentially first-in-class, dual-antigen, immune-modulatory therapy that stimulates T cells to target tumoral immune escape via key checkpoint molecules IDO and PD-L1. It is thought that activating IDO/PD-L1-specific T cells in cancer patients through vaccination may support anticancer immunity by restricting immunosuppressive signaling and restoring the tumor immune microenvironment to render the tumor more susceptible to anti-PD-1 blockade. Thus there is a rationale for combining IO102-IO103 with anti-PD-1 therapy in the first-line treatment of metastatic tumors, such as NSCLC, SCCHN, or UBC. Combined IO102-IO103 and anti-PD-1 therapy (nivolumab) has already shown a robust signal of clinical activity (overall response rate [ORR], 80%; complete response rate [CRR], 43%; median progression-free survival [PFS], 26 months) and was well tolerated with minimal added toxicity to nivolumab in a Phase 1/2 study of anti-PD1-naïve patients with metastatic melanoma (Kjeldsen, et al. Nat Med 2021). Methods: This is a Phase 2, international, multicenter (US and Europe), non-comparative, open-label, multi-arm (basket) trial (EudraCT No. 2021-003026-69; ClinicalTrials.gov No. NCT05077709). Patients with recurrent, unresectable or metastatic solid tumors in 3 indications and no prior treatments for metastatic disease are being enrolled: NSCLC with a PD-L1 Tumor Proportion Score (TPS) ≥50% (Arm A); SCCHN with PD-L1 Combined Positive Scores (CPS) ≥20 (Arm B); or UBC with PD-L1 CPS ≥10 and not eligible for platinum-containing chemotherapy (Arm C). All patients, ̃30 in each arm, will receive 3-week cycles of IO102-IO103 (85-85 µg on Day [D] 1 and 8 of Cycle 1 and 2, and D1 thereafter) subcutaneously plus pembrolizumab (200 mg on D1) intravenously, for up to 2 years. Primary endpoints are ORR by RECIST v1.1 or 6-month PFS rate by investigator assessment (to be analyzed either 6 months after last patient started treatment or after target ORR is achieved, whichever is earliest). Secondary endpoints include PFS, duration of response, complete response rate, disease control rate, time to response, overall survival, and safety. Exploratory endpoints include biomarker and immune marker correlative studies, and PFS by iRECIST. The trial will assess the opportunity for a positive risk–benefit based on 2 efficacy boundaries for the ORR and 6-month PFS rate in each arm, with cohort expansion permitted if a clinically relevant efficacy signal is observed. Clinical trial information: EudraCT No. 2021-003026-69; ClinicalTrials.gov No. NCT05077709.

Overall Survival and Durable Responses in Patients With BRAF V600-Mutant Metastatic Melanoma Receiving Dabrafenib Combined With Trametinib

PURPOSE

To report the overall survival (OS) and clinical characteristics of BRAF inhibitor-naive long-term responders and survivors treated with dabrafenib plus trametinib in a phase I and II study of patients with BRAF V600 mutation-positive metastatic melanoma.

METHODS

BRAF inhibitor-naive patients treated with dabrafenib 150 mg twice daily plus trametinib 2 mg daily (the 150/2 group) from the non-randomly assigned (part B) and randomly assigned (part C) cohorts of the study were analyzed for progression-free and OS separately. Baseline characteristics and factors on treatment were analyzed for associations with durable responses and OS.

RESULTS

For BRAF inhibitor-naive patients in the 150/2 groups (n = 78), the progression-free survival at 1, 2, and 3 years was 44%, 22%, and 18%, respectively, for part B (n = 24) and 41%, 25%, and 21%, respectively, for part C (n = 54). Median OS was 27.4 months in part B and 25 months in part C. OS at 1, 2, and 3 years was 72%, 60%, and 47%, respectively, for part B and 80%, 51%, and 38%, respectively, for part C. Prolonged survival was associated with metastases in fewer than three organ sites and lower baseline lactate dehydrogenase. OS at 3 years was 62% in patients with normal baseline lactate dehydrogenase and 63% in patients with a complete response.

CONCLUSION

Dabrafenib plus trametinib results in a median OS of more than 2 years in BRAF inhibitor-naive patients with BRAF V600 mutation-positive metastatic melanoma, and approximately 20% were progression free at 3 years. Durable responses occurred in patients with good prognostic features at baseline, which may be predictive.

Ipilimumab (Ipi) retreatment at 10 mg/kg in patients with metastatic melanoma previously treated in phase II trials

9059

Background: Ipi is a fully human monoclonal antibody that binds to cytotoxic T-lymphocyte antigen-4 to augment antitumor immune responses. In phase III study MDX010-20, where patients (pts) could be retreated if they met safety criteria and achieved an objective response or stable disease ≥3 months from the end of the induction period (q3 weeks for 4 doses), 21 of 31 pts (68%) retreated with Ipi reestablished disease control. CA184-025 is a roll-over study of extended Ipi treatment or survival follow-up in pts who received Ipi in phase II trials, with the primary objective of evaluating safety during extended treatment. We report the safety profile in pts retreated with Ipi in study 025. Methods: Eligible pts in phase II trials CA184-004, -007, -008, -022, MDX010-08, or -015 were enrolled in study 025 (N=248) to receive retreatment (at the time of progression), extended maintenance (if no prior progression), or survival follow-up only. Pts were ineligible for retreatment if they had experienced a grade 3-4 non-skin toxicity during prior Ipi therapy. Ipi was administered at 10 mg/kg, q3 weeks for 4 doses, to 111 pts who initially received Ipi induction at 0.3, 3, or 10 mg/kg in a parent study. Results: In this selected population of eligible pts, the nature and frequency of immune-related adverse events (irAEs) during retreatment were similar to those reported in previous studies, which most commonly affected the GI tract and skin (Table). There were no new types of drug-related irAEs and no grade 5 irAEs upon retreatment. Conclusions: Retreatment with Ipi at 10 mg/kg in these pts was generally well tolerated and the safety profile was similar to that during induction dosing in the parent studies. The higher frequencies of irAEs at lower doses should be interpreted with caution given the small sample sizes. An ongoing, randomized phase II trial will evaluate the clinical benefit of Ipi retreatment. Clinical trial information: NCT00162123. [Table: see text]

Long-term survival in patients with metastatic melanoma who received ipilimumab in four phase II trials

9053

Background: Ipilimumab (Ipi) has shown improved overall survival (OS) in two phase III trials of patients (pts) with metastatic melanoma (MM), with survival follow-up of >4 years in one trial. The present analyses provide survival follow-up of >5 years in four phase II trials of Ipi in MM. Methods: Pts with MM were enrolled in one of four phase II trials: (1) CA184-004, a biomarker study with Ipi at 3 or 10 mg/kg in treatment-naive (TN) and previously treated (PT) pts; (2) CA184-007, with Ipi at 10 mg/kg +/- prophylactic budesonide in TN and PT pts; (3) CA184-008, a single-arm study with Ipi at 10 mg/kg in PT pts; and (4) CA184-022, a dose-ranging study of Ipi at 0.3, 3, or 10 mg/kg in PT pts (crossover from lower dose groups to 10 mg/kg was allowed upon disease progression). Ipi was administered q3 wk x4 (induction), followed by maintenance (q12 wk from week 24) in eligible pts. Some pts were retreated with Ipi at 10 mg/kg upon disease progression. Along with survival data collected through March 2012 for studies 007, 008, and 022, we report updated 5-year OS data for study 004 collected through September 2012. Results: Five-year OS rates for TN and PT pts are reported in studies 007, 008, and 022, with combined analyses for TN and PT pts within each dose group in study 004 (Table). The results show that survival rates reach a plateau beginning at year 3. Conclusions: In pts who received Ipi at 3 or 10 mg/kg in phase II studies, regardless of prior treatment, a proportion (12.3–49.5%) remained alive 5 years after the start of treatment. These results demonstrate long-term survival with Ipi therapy in MM. An ongoing phase III trial will compare OS for Ipi at 3 vs 10 mg/kg in pts with MM. Clinical trial information: NCT00162123. [Table: see text]

CA184-104: Randomized, multicenter, double-blind, phase III trial comparing the efficacy of ipilimumab (Ipi) with paclitaxel/carboplatin (PC) versus placebo with PC in patients (pts) with stage IV/recurrent non-small cell lung cancer (NSCLC) of squamous histology

TPS8117

Background: Improved outcomes for squamous, advanced NSCLC—beyond standard platinum doublets—have not been demonstrated. Data suggestive of response to immune therapies in squamous NSCLC support investigation in this subtype. Ipi, a fully human monoclonal antibody which binds CTLA-4, augments antitumor immune responses. Ipi improved overall survival (OS) in advanced melanoma, with side effects managed using product-specific treatment guidelines. A randomized phase II study of phased Ipi/PC (Ipi started after 2 cycles of PC) in pts with stage IV NSCLC showed significant improvement in progression-free survival (PFS), as measured by mWHO or immune-related response criteria (irRC), with a trend toward prolonged OS, over chemotherapy alone; irRC were derived from WHO criteria to better capture response patterns observed with Ipi. Improvement in PFS and OS appeared greater in tumors of squamous histology. Ipi did not exacerbate PC toxicity, and immune-related adverse events were managed using protocol-specific guidelines. This global (~253 sites among 34 countries) phase III trial (ClinicalTrials.gov identifier NCT01285609) is investigating whether phased Ipi/PC will prolong OS in first-line pts with squamous NSCLC. Methods: Stage IV/recurrent squamous NSCLC with ECOG 0-1 will be included; pts with CNS metastases or history of autoimmune disease will be excluded. Pts are randomized to 2 cycles of PC (175 mg/m2 and AUC=6, respectively; IV), followed by 4 cycles of study drug (Ipi in Arm A, placebo in Arm B; IV) with 4 additional cycles of PC (total 6 cycles). Pts without progressive disease (PD) after induction receive maintenance therapy with blinded study drug Q12W until PD per mWHO. The study will enroll an estimated 920 pts, randomized 1:1 between arms. The primary endpoint is OS; secondary endpoints include OS among pts who receive blinded therapy, PFS, and best overall response rate. Safety is an exploratory objective of the trial. Clinical trial information: NCT01285609.