Predictive blood-based markers of response to VEGF inhibitors in NSCLC

Inhibitors of the VEGF pathway, including the VEGF antibody bevacizumab (BV) and multitargeted VEGFR tyrosine kinase inhibitors such as vandetanib, have in some cases improved progression-free survival (PFS) and/or overall survival (OS) in patients with advanced NSCLC. While benefits in the overall NSCLC population have thus far been modest, it is clear that a subset of patients have dramatic benefit, while others may experience no benefit or even life-threatening toxicities. Furthermore, virtually all patients who respond inevitably develop therapeutic resistance. Thus, the development of markers predictive of response or resistance for VEGF inhibitors is critically needed to advance NSCLC treatment. There are currently no validated predictive markers for VEGF inhibitors, and the development of such markers is made more challenging by the impact of both tumor- and host-derived circulating factors on tumor angiogenesis. Useful predictive markers will likely need to reflect factors from both sources. We hypothesize that by comprehensively profiling angiogenesis-related CAFs and other peptides in the blood, as well as germline variations in angiogenesis-related genes, non-invasive predictive markers for identifying which patients benefit from VEGF inhibitors (alone or with chemotherapy) can be developed and validated.

The investigators of this proposal have a longstanding collaboration to develop predictive markers for VEGF inhibitors and, along with other investigators, have identified three promising and potentially complementary approaches using blood-based markers that will be tested in this grant. We have also played leadership roles in major randomized clinical trials of VEGF inhibitors, which have enabled us to leverage a unique set of resources to address these questions.

In Aim 1, we will use multiplexed CAF profiling to identify high-priority candidate predictive markers for differential benefit from VEGF inhibitors with chemotherapy compared to chemotherapy alone using two independent sets of samples from randomized phase II trials: one testing bevacizumab (BV) with chemotherapy (pemetrexed/carboplatin or Pem/C) vs. Pem/C alone (BATTLE-FL) trial, and another testing the VEGFR/EGFR tyrosine kinase inhibitor vandetanib (VAN) plus carboplatin/paclitaxel (VCP) vs. CP, in first-line NSCLC trial. We will also test CAF markers of benefit for VAN vs. standard therapy with erlotinib using specimens from a recently completed randomized phase III trial (ZEST).

In Aim 2, we will use MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectroscopy to develop a serum proteomic classifier for benefit for VEGF inhibitors, using samples from the same trials as in Aim 1. We previously used a similar approach to develop a serum proteomic marker of benefit (Veristrat) for EGFR inhibitors.

Finally, in Aim 3, we will validate a signature of SNPs from three angiogenesis-related genes that were found to be predictive of benefit for BV with CP (BCP) vs. CP in the ECOG4599 trial. This will be tested in the same three trials of VEGF inhibitors. It is worth noting that our interest is not in developing markers for a particular drug, but rather to identify markers and pathways relevant to predicting response or resistance to inhibitors of the VEGF pathway, a validated therapeutic target in NSCLC. Our data thus far suggest there will be overlap in markers for BV and VEGFR TKIs but it will be important to determine whether this is true, particularly as more potent and specific inhibitors are tested.

Impact. This project has the potential to address a critical unmet need in NSCLC by producing validated, non-invasive blood-based predictive markers for identifying patients more likely to benefit from VEGF inhibitors, and can provide critical insights into mechanisms of resistance to guide future combination regimens.