Docoraatsthesis Miguel Lemaire

Op 12 september 2013 behaalde Miguel Lemaire aan de faculteit geneeskunde en farmacie van de VUB de titel van doctor in de medische wetenschappen (PhD in medical sciences) voor zijn onderzoek met als titel: “The potential role of the insulin-like growth factor-I pathway in the development of new therapeutic strategies in multiple myeloma.”

De insulin-like growth factor-1 (IGF-1) pathway speelt een belangrijke rol in de pathologie van multipel myeloma (MM). Eerdere studies hebben aangetoond dat inhibitie van het IGF-1 receptor met picropodophyllin (PPP) belangrijke anti-tumor effecten kan induceren in MM. In zijn proefschrift evalueerde Miguel Lemaire nieuwe methodes om MM te behandelen, gebaseerd op de targeting van de IGF-1 pathway. In eerste instantie werd PPP gecombineerd met de histon deacetylase inhibitor (HDACi) LBH589. Aan de hand van in vitro studies in humane cellijnen bestudeerde hij de effecten van deze combinatie op celdood, cel cyclus en differentiële genexpressie. Hij onderzocht eveneens de in vivo effecten met behulp van het 5T33MM muis model. Deze studies toonden aan dat de combinatie van PPP met LBH589 sterkere anti-MM effecten heeft dat elke medicament afzonderlijk.In een tweede luik evalueerde Miguel Lemaire het gebruik van Nanobodies als tools voor de specifieke moleculaire targeting van myeloom cellen. Nanobodies zijn de kleinste antigen-bindende fragmenten afgeleid van de heavy chain-only antilichamen, die van nature voorkomen in Camelidae. Hij produceerde Nanobodies gericht tegen het M-proteïne van het muis 5T2MM model. In een proof-of-principle studie kon hij aantonen dat zulke Nanobodies gebruikt kunnen worden voor in vivo imaging en therapeutische toepassingen.

Het onderzoek van Miguel Lemaire werd uitgevoerd binnen de onderzoeksgroep hematologie-immunologie, onder leiding van Prof. dr. Karin Vanderkerken. Zijn wetenschappelijk werk vormde verscheidene malen het onderwerp van publicaties in internationale, peer-reviewed tijdschriften en leidde tot het neerleggen van zijn proefschrift.

English version

Multiple myeloma (MM) is an incurable hematological cancer characterized by the expansion of malignant monoclonal plasma cells within the bone marrow (BM), overproduction of monoclonal paraprotein and development of bone lesions. The bidirectional interactions between the MM cells and the BM microenvironment will alter homeostasis in favor of tumor growth, proliferation and survival and eventually induce angiogenesis, drug resistance and bone lesions. The Insulin-like growth factor-I (IGF-I) pathway plays a key role in the pathobiolology of the disease, and therefore it is an attractive target for therapeutic purposes. Previous research in our group has demonstrated that inhibition of the IGF-I tyrosine kinase receptor (TKR) with picropodophyllin (PPP) leads to a decreased tumor proliferation and survival as well in vitro as in vivo. Despite the promising results obtained, this strategy failed to completely eradicate the tumor. In this thesis we evaluated new methods to improve these anti-MM effects.

Firstly, we combined PPP with a histone deacetylase inhibitor (HDACi) LBH589 in order to potentiate the anti-MM effects observed with PPP. Therefore we initially investigated the anti-MM effects of HDACi LBH589 as mono-therapy in different human cells lines and in the 5T33MM model. We observed that LBH589 is able to reactivate Polycomb target genes and induce apoptosis in the human cell lines RPMI 8226 and U-266-1984. More important, prophylactic treatment of 5T33MM mice with LBH589 resulted in a significant reduction of tumor cells present in the BM and of circulating paraprotein in the serum and increased survival rate compared to control groups. The next step was to use PPP and LBH589 simultaneously. Compared to single-treatment, in vitro combinatorial treatment of the human cell line RPMI 8226 resulted in increased apoptosis and cleavage of casape-8, accumulation of tumor cells in the G2-M phase and downregulation of cell cycle proteins. Similar in vitro results were observed using isolated cells from the 5T33MM murine model. Also, in vitro combinatorial treatment resulted in altered expression profiles of different groups of genes such as genes regulating apoptosis and cell cycle. In vivo treatment of 5T33MM mice with the PPP-LBH589 combination showed a significantly prolonged survival rate compared to single treatment and untreated groups.

Secondly, we wanted to use Nanobodies for the specific delivery of siRNA into the MM cells in order to interfere with the expression of the IGF-I TKR in the 5T2MM murine model. Nanobodies are the smallest antigen-binding fragments derived from the heavy chain-only antibodies naturally occurring in Camelidae and thanks to their biochemical properties they are well suited for imaging and therapeutic purposes. After immunization of a dromedary with 5T2MM idiotype (5T2id) we were able to isolate Nanobodies with high affinity and specificity as demonstrated by ELISA, affinity binding assay and FACS analysis.  Based on those results we selected Nanobody R3B23 to test its applicability in vivo. Biodistribution studies and SPECT/micro-CT scans using 99mTechnetium-labeld Nanobody revealed specific targeting of the 5T2MMid in vivo. Moreover, treatment of 5T2MM mice in a minimal residual disease (MRD)-like stadium with 177Lutetium-conjugated Nanobody resulted in a significant decrease of circulating paraprotein, suggesting a reduction in tumor load through specific targeting of tumor cells.

In resume, we have demonstrated that the anti-MM effects of the IGF-1 RTK inhibitor PPP are potentiated when used in combination with the HDACi LBH589. The evidence here provided offers a basis for the clinical evaluation of this combination. Moreover, we have shown that it is possible to use Nanobodies as tools for the molecular targeting of tumor specific markers in MM offering new perspectives for the development of novel diagnostic and therapeutic strategies.



  • Lemaire M, D’Huyvetter M, Lahoutte T, Van Valckenborgh E, Menu E, De Bruyne E, Kronenberger P, Wernery U, Muyldermans S, Devoogdt N, Vanderkerken K. Imaging and radioimmunotherapy of multiple myeloma with anti-idiotypic Nanobodies. Leukemia2013 Oct 9. doi: 10.1038/leu.2013.292. [Epub ahead of print] PubMed PMID: 24166214.
  • Lemaire M, Fristedt C, Agarwal P, Menu E, Van Valckenborgh E, De Bruyne E, Österborg A, Atadja P, Larsson O, Axelson M, Van Camp B, Jernberg-Wiklund H, Vanderkerken K. The HDAC inhibitor LBH589 enhances the antimyeloma effects of the IGF-1RTK inhibitor picropodophyllin. Clin Cancer Res. 2012 Apr 15;18(8):2230-9. doi: 10.1158/1078-0432.CCR-11-1764. Epub 2012 Mar 5. PubMed PMID: 22392915.
  • Lemaire M, Deleu S, De Bruyne E, Van Valckenborgh E, Menu E, Vanderkerken K. The microenvironment and molecular biology of the multiple myeloma tumor. Adv Cancer Res. 2011;110:19-42. doi: 10.1016/B978-0-12-386469-7.00002-5. Review. PubMed PMID: 21704227.
  • Kalushkova A, Fryknäs M, Lemaire M, Fristedt C, Agarwal P, Eriksson M, Deleu S, Atadja P, Osterborg A, Nilsson K, Vanderkerken K, Oberg F, Jernberg-Wiklund H. Polycomb target genes are silenced in multiple myeloma. PLoS One. 2010 Jul 9;5(7):e11483. doi: 10.1371/journal.pone.0011483. PubMed PMID: 20634887; PubMed Central PMCID: PMC2901331.
  • Deleu S, Lemaire M, Arts J, Menu E, Van Valckenborgh E, King P, Vande Broek I, De Raeve H, Van Camp B, Croucher P, Vanderkerken K. The effects of JNJ-26481585, a novel hydroxamate-based histone deacetylase inhibitor, on the development of multiple myeloma in the 5T2MM and 5T33MM murine models. Leukemia. 2009 Oct;23(10):1894-903. doi: 10.1038/leu.2009.121. Epub 2009 Jun 4. PubMed PMID: 19494837.
  • Deleu S, Lemaire M, Arts J, Menu E, Van Valckenborgh E, Vande Broek I, De Raeve H, Coulton L, Van Camp B, Croucher P, Vanderkerken K. Bortezomib alone or in combination with the histone deacetylase inhibitor JNJ-26481585: effect on myeloma bone disease in the 5T2MM murine model of myeloma. Cancer Res. 2009 Jul 1;69(13):5307-11. doi: 10.1158/0008-5472.CAN-08-4472. Epub 2009 Jun 16. PubMed PMID: 19531653.

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