Massachusetts General Hospital – A DES Daughter's Blog

Lung cancer cell image — Screening tumors could lead to smarter decisions about which cancer treatments will work best for individual patients.

Some cancer centers already take biopsies of tumors and run them through genetic tests, to get a better sense of what’s driving the cancer. That information can be helpful in deciding which of the growing number of targeted anti-cancer drugs will work best to stop those growths.

Abstract

Targeted cancer therapies have produced substantial clinical responses, but most tumors develop resistance to these drugs. Here, we describe a pharmacogenomic platform that facilitates rapid discovery of drug combinations that can overcome resistance. We established cell culture models derived from biopsy samples of lung cancer patients whose disease had progressed while on treatment with EGFR or ALK tyrosine kinase inhibitors and then subjected these cells to genetic analyses and a pharmacological screen. Multiple effective drug combinations were identified. For example, the combination of ALK and MEK inhibitors was active in an ALK-positive resistant tumor that had developed a MAP2K1 activating mutation, and the combination of EGFR and FGFR inhibitors was active in an EGFR mutant resistant cancer with a novel mutation in FGFR3. Combined ALK and SRC inhibition was effective in several ALK-driven patient-derived models, a result not predicted by genetic analysis alone. With further refinements, this strategy could help direct therapeutic choices for individual patients.

Sources and more information

Patient-derived models of acquired resistance can identify effective drug combinations for cancer, sciencemag,
DOI: 10.1126/science.1254721, November 13 2014.
The Cancer Breakthrough With Big Implications,
Time, Nov. 13, 2014.
Direct drug screening of patient biopsies could overcome resistance to targeted therapy, massgeneral, November 13, 2014.

A protein engineered by Massachusetts General Hospital investigators to combine a molecule targeting a tumor antigen with an immune-function stimuating protein prolonged survival in animal models of ovarian cancer and mesothelioma.

A novel approach to cancer immunotherapy – strategies designed to induce the immune system to attack cancer cells – may provide a new and cost-effective weapon against some of the most deadly tumors, including ovarian cancer and mesothelioma. Investigators from the Massachusetts General Hospital (MGH) Vaccine and Immunotherapy Center report in the Journal of Hematology & Oncology that a protein engineered to combine a molecule targeting a tumor-cell-surface antigen with another protein that stimulates several immune functions prolonged survival in animal models of both tumors.

Read Antigen-targeting fusion protein should be less expensive, more accessible than current approaches, MGH News Release, 05/Mar/2014

A novel mycobacterial Hsp70-containing fusion protein targeting mesothelin augments antitumor immunity and prolongs survival in murine models of ovarian cancer and mesothelioma

Abstract

Background

Although dendritic cell (DC) vaccines are considered to be promising treatments for advanced cancer, their production and administration is costly and labor-intensive. We developed a novel immunotherapeutic agent that links a single-chain antibody variable fragment (scFv) targeting mesothelin (MSLN), which is overexpressed on ovarian cancer and mesothelioma cells, to Mycobacterium tuberculosis (MTB) heat shock protein 70 (Hsp70), which is a potent immune activator that stimulates monocytes and DCs, enhances DC aggregation and maturation and improves cross-priming of T cells mediated by DCs.

Methods

Binding of this fusion protein with MSLN on the surface of tumor cells was measured by flow cytometry and fluorescence microscopy. The therapeutic efficacy of this fusion protein was evaluated in syngeneic and orthotopic mouse models of papillary ovarian cancer and malignant mesothelioma. Mice received 4 intraperitoneal (i.p.) treatments with experimental or control proteins post i.p. injection of tumor cells. Ascites-free and overall survival time was measured. For the investigation of anti-tumor T-cell responses, a time-matched study was performed. Splenocytes were stimulated with peptides, and IFNγ- or Granzyme B- generating CD3+CD8+ T cells were detected by flow cytometry. To examine the role of CD8+ T cells in the antitumor effect, we performed in vivo CD8+ cell depletion. We further determined if the fusion protein increases DC maturation and improves antigen presentation as well as cross-presentation by DCs.

Results

We demonstrated in vitro that the scFvMTBHsp70 fusion protein bound to the tumor cells used in this study through the interaction of scFv with MSLN on the surface of these cells, and induced maturation of bone marrow-derived DCs. Use of this bifunctional fusion protein in both mouse models significantly enhanced survival and slowed tumor growth while augmenting tumor-specific CD8+ T-cell dependent immune responses. We also demonstrated in vitro and in vivo that the fusion protein enhanced antigen presentation and cross-presentation by targeting tumor antigens towards DCs.