We are the RaCaRe Group, a multidisciplinary research group that forms a strong backbone for the studies and enables truly translational research.

In 2018, we teamed up to study rare cancers given our long-standing history of working together and our previous studies of Merkel cell carcinoma and sarcomas in general. With various educational and research backgrounds, as a team we complement one another, ultimately enabling our multidisciplinary approach aimed at resolving scientific mysteries.

Science relies on teamwork. As such, we continuously probe possibilities to collaborate with other experts who share our passions and research goals, and seek to learn from one other scholars and scientists in a fast-paced research environment.

Tom Böhling, PI

PI, MD, PhD, Professor

Tom, as the senior member of our group, brings his extensive history and wealth of experience in tumour research to RaCeRe, focusing specifically on rare tumour types including sarcomas and brain tumours. Tom worked as a visiting researcher at the Rizzoli Institute in Bologna, Italy, and has served as a key member of the Scandinavian Sarcoma Group. Tom has published more than 170 original peer-reviewed articles, and contributed to several volumes of the World Health Organization’s Blue Book series.

In his limited free time, he enjoys listening to baroque music, visiting art galleries and caring for his 500 Rhododendrons.

Virve Koljonen, PI

PI, Professor, MD, PhD, plastic surgeon

Virve, a plastic surgeon and Merkel cell carcinoma research old-timer, actively cares for clinical patients and treats skin cancer patients at the Helsinki University Hospital. In total, she has published over 120 peer-reviewed articles, and claims more than 1200 citations to her work. Amongst her publications, more than 40 focus on Merkel cell carcinoma. In addition, she has supervised three post-graduate theses on Merkel cell carcinoma. As our clinical expert, she always places the patient first. Currently, she serves as one of four PIs in the RaCaRe Group.

In her spare time, she enjoys reading locked-room mysteries and baking, and analyses folklore myths applying scientific methods.

Harri Sihto, PI

PI, Docent, PhD

Harri, a biochemist and an adjunct professor in cancer biology at the University of Helsinki, focuses on rare cancers and novel therapies targeting them. Harri is also a co-founder and chairman of the board of biotech company Sartar Therapeutics, which develops new targeted therapies for a rare soft-tissue tumour — the gastrointestinal stromal tumour or GIST. As an innovative and prolific researcher, he has published more than 70 international peer-reviewed studies, claiming  more than 4000 citations to those publications. Currently, he serves as one of three PIs within the RaCaRe Group.

During the Finnish summer, you can find Harri on his balcony admiring the blooms of his various species of chillies.

Mika Sampo

MD, PhD, oncologist, pathologist

Mika specialised in oncology and now works as a pathology trainee at HUSLAB within Helsinki University Hospital and the University of Helsinki, where he also delivers lecturers in pathology. His thesis, ‘Optimal Use of Treatment Modalities and Treatment Results of Osteosarcoma and Soft Tissue Sarcomas’, was completed in 2011, and he has published 15 peer-reviewed articles primarily on optimising the use of treatment modalities, radiation therapy and chemotherapy in soft tissue sarcoma. He is currently supervising his first post-graduate student on the prognostic importance of proliferation in soft tissue sarcoma. More recently, Mika’s interests shifted to focus on soft tissue sarcomas, proliferation markers and further refining his prognostic tool to improve patient selection for adjuvant chemotherapy. Currently, he serves as one of four PIs within the RaCaRe Group.

Helka Sahi

MD, PhD, post-doc researcher, dermatologist

Helka is dermatologist now working with general dermatology and skin cancers in the Helsinki University Hospital.  She completed her thesis on Merkel cell carcinoma subgroups in 2014, focusing on polyomavirus infection and immunocompromising states in the etiology of the carcinoma. Helka has an interest in immunology, and has published 8 peer-reviewed articles on Merkel cell carcinoma. She has also worked as a clinical researcher in the field of cutaneous lymphomas, and hopes to broaden her expertise on the topic. Currently, she serves as post-doc researcher within the RaCaRe Group. Helka aims to support fellow young scientist and is happy to be the go-to person in times of despair.  

Tuukka Veija

MD, PhD, post-doc researcher, surgery resident

Tuukka graduated from the Faculty of Medicine, University of Helsinki in 2018. He has conducted research on Merkel cell carcinoma since 2013. As a medical doctor he has special interest in diseases that are disfiguring. This interest has driven his interest towards the aggressive skin cancer, Merkel cell carcinoma. His thesis,         “ Molecular aberrations in Merkel cell carcinoma with distinction of polyoma virus positive and negative tumors” was finalized in June 2019.  Besides medical science he’s passionate about cooking and tennis.

Benjamin Sundqvist


Benjamin defended his doctoral thesis in the autumn of 2023 about the Merkel cell carcinoma studies. 

In his spare time, Benjamin enjoys tennis and long-distance running.

Nanna Merikoski

Laboratory analyst

Nanna is highly experienced laboratory technician with a long and extensive research career. After graduating from Oulu University of Applied Sciences, she has gathered her expertise in multiple Universities in Finland as well as CROs specializing in in vivo, cell culturing, drug discovery, immunohistochemistry and the list goes on.

In her spare time Nanna likes to go bouldering with her colleagues or walk and catch Pokémon with her 3 children.

Anna-Stiina Meriläinen

Ph.D. student, plastic surgeon

Anna-Stiina is  the second plastic surgeon in the team. She works full time in the plastic surgery clinical practise and ended up doing research on eccrine porocarcinoma partly by accident. She had a resident presentation on porocarcinoma some years ago with Virve and got interested in porocarcinoma and research.  

She is truly passionate about her work and enjoys team work. She spends her spare time with friends, family and her little chihuahua.


Kirsi Toivanen

MSc, PhD student

Kirsi is a biochemist who graduated from the University of Turku and has a background in cancer research. She started carrying out her doctoral degree in the group in January 2020. In her research, she focuses on discovering novel drug targets in liposarcoma.

In her free time, she likes to go for walks with her cat and enjoys going out for dinner. Music is also a big part of her life as she sings in a choir and likes to rehearsal the songs in the cell culture room for her colleagues’ delight.

Maya Puttonen

MD, Ph.D student 

Maya graduated from the Faculty of Medicine, Okayama University, Japan in 2020. Aspiring to become a doctor who actively conducts researches and effectively turns clinical questions into patients´ benefits, she joined RaCaRe group. Currently she works on the porocarcinoma project. 

Alongside the research work, she is preparing for Finnish medical licensing so she could broaden her opportunities for an impactful and benefiting work. During summertime, she is probably in the middle of a lake rowing.  

Sami Salmikangas

MSc, PhD student


Sami graduated from the University of Jyväskylä in 2020 with Cellular and Molecular Biology as his major subject, and he has expertise in structural biology, DNA cloning, cell culturing and transfections, and various microscopy techniques. Sami's studies focus on characterizing potential novel biomarkers and therapeutic targets for GISTs. He is highly passionate about his field and work, likes to find alternative solutions to problems, and loves to teaching as well.

During his spare time, Sami is most probably either disc golfing or jogging with his Swedish Vallhund. If the weather is poor, he prefers watching hockey or playing video games.

Iina Lindholm



Iina is a Translational Medicine Master's student at the University of Helsinki, holding a Bachelor of Science with a major in Molecular Biosciences and a minor in Physiology and Neuroscience. As a research assistant, she currently contributes to unraveling the mysteries of the MYB gene in cancer. 

Outside the lab, she finds balance by hitting the gym and indulging in geocaching adventures with her partner and dog companion.