AT ASCO 2017

CHICAGO (FRONTLINE MEDICAL NEWS)– A combination of the programmed death 1 (PD-1) inhibitor nivolumab (Opdivo) with an experimental immune-enhancing monoclonal antibody induced clinical responses in patients with several different solid tumor types, including some patients who had disease progression on a PD-1 inhibitor, investigators reported.

The investigational agent, euphoniously named BMS-986156 (986156), is a fully human immunoglobulin G1 agonist monoclonal antibody with high affinity binding for the glucocorticoid-induced tumor necrosis factor receptor–related gene (GITR).

GITR is a costimulatory activating receptor that is upregulated on T-cell activation. In the tumor microenvironment, Tregs express GITR at higher levels than Teffs.

BMS-986156156 “induces potent antitumor immunity by several mechanisms. First, it increases T-effector cell survival and function. Second, it promotes T-regulatory cell depletion and reduction through its conversion to other immune cells. As well, it reduces T-reg-mediated suppression of T-effector cells,” said Lillian L Siu, MD , from the Princess Margaret Hospital in Toronto.

In preclinical studies, the combination of an anti-GITR and an anti-PD-1 agent showed synergistic activity against murine tumor models.

Dr. Siu and colleagues conducted a phase I/IIa study of BMS-986156 with or without nivolumab in 66 patients with advanced solid tumors.

The 29 patients assigned to BMS-986156 monotherapy were started at 10 mg every 2 weeks, which was gradually titrated upward to find the maximum tolerated dose of 240 mg Q2 weeks.

The 37 patients assigned to the combination were started on a dose of 30-mg nivolumab and 240-mg BMS-986156. The nivolumab dose but not the BMS-986156 dose was then titrated upward to a maximum tolerated dose of 240 mg for each agent. This dose was based on pharmacodynamic and pharmacokinetic studies.

Tumor types included melanoma, cervical, colon, breast, renal, pancreatic, and ovarian cancers and cholangiocarcinoma.

Approximately one-third of patients in the monotherapy arm and nearly half of those in the combination arm had undergone three or more prior therapies for cancer. Seven patients in the monotherapy group and five in the combination group had previously received a PD-1 or PD-L1 inhibitor.

The median duration of treatment ranged from 7 to 15.5 weeks for 156 monotherapy and 8 to 18 weeks for the combination.

Safe and well tolerated

There were no dose-limiting toxicities or treatment-related deaths in either study arm, and patients tolerated both BMS-986156 monotherapy and the combination well. There were no grade 3 or 4 adverse events in the monotherapy arm.

“In the combination arm, the toxicity is very consistent with that observed with nivolumab monotherapy alone,” Dr. Siu said.

The only grade 4 event in this group was an increase in blood creatine phosphokinase. In this group, there were six grade 3 adverse events, including one each of colitis, dehydration, fatigue and increases in hepatic enzymes, lipase increase, and lung infection.

In pharmacokinetic studies, the action of the combinations was linear, with dose-related increases in exposure, and the combination had low immunogenicity, with no patients developing persistent antidrug antibodies.

The combination was also associated with increases in natural killer and CD8 cells in peripheral blood. Immunophenotyping of patients treated with the 240/240-mg dose of the combination showed increased proliferation and activation of CD8 effector cells, central memory cells, and CD4 cells.

Early promise

Dr. Siu reviewed interim efficacy results for the five patients treated with the combination who had responses.

For example, a 44-year-old woman with metastatic cervical cancer – a tumor type known to have high levels of GITR expression – had received more than three prior lines of therapy, including chemotherapy with a vascular endothelial growth factor inhibitor. She had a partial response with the combination, with an approximately 62% reduction in tumor burden. She had an ongoing response to the combination at the time of data cutoff in March 2017.

The combination also showed efficacy against adenocarcinoma of the hepatopancreatic duct (ampulla of Vater), a tumor type not typically responsive to immunotherapy. The 60-year-old patient (sex not disclosed), had received three prior lines of chemotherapy and also had a partial response at the 240/240 dose, with the best change in tumor burden an estimated 38% reduction. The duration of the response at the time of data cutoff was 16 weeks and was ongoing.

Two other patients had partial responses after progression on an anti-PD-1 agents, including one with nasopharyngeal cancer who had received three prior lines of therapy, including chemotherapy and a PD-1 inhibitor. This patient had an approximately 43% reduction in tumor burden, with a 17-week duration of response and ongoing response at data cutoff.

The other patient was a 59-year-old with malignant melanoma that had advanced on pembrolizumab (Keytruda). This patient too had received three prior lines of therapy, including a BRAF inhibitor, anti-PD-1, and BRAF/MEK inhibitor combination.

This patient had a response of 24-week duration at the time of data cutoff. It is ongoing, Dr. Liu said.

“This combination of immune agonists was safe with a low incidence of severe toxicity, and there was no maximum tolerated dose; however, the maximum administered dose may not be the most effective dose to move forward,” commented Siwen Hu-Lieskovan MD, PhD , from the Jonsson Comprehensive Cancer Center at the University of California, Los Angeles, the invited discussant.

She noted that activity of the combination has been seen in a wide range of tumor histologies but added that further biomarker studies will be critical for identifying patients who are likely to respond.

The study was funded by Bristol-Myers Squibb. Dr. Siu disclosed research funding from the company and others and consulting/advising several different companies. Dr. Hu-Lieskovan disclosed institutional research funding from BMS and other companies, as well as honoraria and consulting and serving in an advisory capacity for companies other than BMS. Several coauthors are employees of the company.