# Atezolizumab and motixafortide, cobimetinib or simlukafusp alfa in pretreated advanced pancreatic cancer: phase I/IIb MORPHEUS-PDAC umbrella study

## TL;DR

This study evaluated combinations of atezolizumab with other drugs in advanced pancreatic cancer patients, finding limited efficacy and manageable safety.

## Contribution

A novel umbrella trial design enabled rapid evaluation of three atezolizumab combinations in pretreated advanced pancreatic cancer.

## Key findings

- Atezolizumab combinations showed limited efficacy as second-line or third-line treatments for metastatic PDAC.
- Objective response rates were highest with atezolizumab-simlukafusp alfa q3w (16.7%) in third-line treatment.
- Adverse event rates were high but generally consistent with known safety profiles of the drugs.

## Abstract

The MORPHEUS platform comprised multiple open-label, randomized, phase Ib/II trials to identify early signals with different treatment combinations across multiple cancers. MORPHEUS-PDAC (NCT03193190) evaluated atezolizumab combinations in pancreatic ductal adenocarcinoma (PDAC). We describe outcomes with atezolizumab plus either motixafortide, cobimetinib, or two simlukafusp alfa regimens.

Eligible patients with advanced, pretreated PDAC were randomized to receive second-line (2 L) atezolizumab plus either motixafortide (BL8040; n = 15), cobimetinib (n = 14), simlukafusp alfa every 2 weeks (q2w; n = 15), or simlukafusp alfa every 3 weeks (q3w; n = 16); or control (mFOLFOX6 [n = 25] or gemcitabine plus nab-paclitaxel [n = 25]). Patients experiencing disease progression or toxicity who met eligibility criteria were enrolled to receive third-line (3 L) atezolizumab plus cobimetinib (n = 14), or atezolizumab plus simlukafusp alfa q2w (n = 1) or q3w (n = 6). Primary endpoints were objective response rates (ORRs) per RECIST 1.1 and safety.

ORRs were 7.1% with atezolizumab-simlukafusp alfa q2w, 8.7% with mFOLFOX6 (both 2 L; 0% in other arms), 14.3% with atezolizumab-cobimetinib, and 16.7% with atezolizumab-simlukafusp alfa q3w (both 3 L). Grade 3-5 adverse event rates were 53.3% (2 L atezolizumab-motixafortide), 64.3% (2 L atezolizumab-cobimetinib), 57.1% (2 L atezolizumab-simlukafusp alfa q2w), 53.3% (2 L atezolizumab-simlukafusp alfa q3w), 63.0% (2 L mFOLFOX6 or gemcitabine-nab-paclitaxel), 50.0% (3 L atezolizumab-cobimetinib), and 100% (3 L atezolizumab-simlukafusp alfa q3w).

The overall safety of atezolizumab combinations was manageable and consistent with each agent’s known safety profile. This novel trial design enabled rapid evaluations of 3 atezolizumab combinations; all had limited efficacy as 2 L or 3 L treatment for metastatic PDAC. New treatments are needed to improve outcomes in previously treated PDAC.