Prediktivni i prognostički značaj polimorfizma u genu PD-L1 i ekspresije PD-L1 u ćelijama karcinoma dojke u postizanju kompletnog patološkog odgovora nakon neoadjuvantne terapije kod različitih molekularnih podtipova karcinoma dojke

Abstract

Karcinom dojke predstavlja najčešću malignu bolest u ženskoj populaciji, čini oko 24 % svih maligniteta kod žena. Uzrok nastanka oboljenja još uvijek je nepoznat te se može govoriti samo o faktorima rizika kao što su rana menarha, kasna menopauza, neradjanje, uzimanje oralnih kontraceptiva, gojaznost, pušenje, fizička neaktivnost. Genetski uzrokovan karcinom dojke javlja se u oko 10 % slučajeva i vezan je za mutacije na genima kao što su BRCA1, BRCA2, PTEN, TP53, MLH1, MSH2, ATM, CHEK2, PALB. Kada je u pitanju liječenje ranog karcinoma dojke na raspolaganju su operativni zahvat, adjuvantna terapija, zračna terapija. Poslednjih godina sve više se kod ranog karcinoma dojke, posebno HER2 pozitivnog i trostruko negativnog prvo ordinira hemioterapija (neoadjuvantna hemioterapija-NAT), a potom planira operativni zahvat. Mjera odgovora na NAT predstavlja kompletan patološki odgovor (pathological complete response-pCR). Patološki odgovor ima prediktivni i prognostički značaj i korelira sa vremenom do povrata bolesti (progression free survival-PFS) i ukupnim preživljavanjem (overall survival-OS). Osim standardnih prediktivnih i prognostičkih faktora koji razvrstavaju karcinom dojke u molekularne podtipove (status ER, PR receptora, HER2 status i Ki 67) novija istraživanja su usmjerena na ispitivanje nivoa ekspresije PD-L1 kod karcinoma dojke kao potencijalnu metu za imunoterapiju. Cilj ove doktorske disertacije bio je ispitati stepen patološkog odgovora nakon NAT kod različitih molekularnih podtipova karcinoma dojke, ispitati PD-L1 ekspresiju kao i polimorfizam PD-L1 gena kod različitih molekularnih podtipova, kao i vezu izmedju molekulanog podtipa, patološkog odgovora tumora, PD-L1 ekspresije i polimorfizma PD-L1 gena. U ovu studiju uključeno je 170 pacijentkinja sa ranim karcinomom dojke kojima je uradjena iglena biopsija tumora te su podvrgnute NAT, a potom operisane. Osim standardnih parametara molekularnog podtipa (ER, PR, HER2, Ki 67) na biopsijskim uzorcima uradjena je imunohistohemija PD-L1 statusa koji je procjenjivan korišćenjem SP142 antitijela na Ventana aparatu. S druge strane polimorfizam PD-L1 gena odredjivan je iz krvi pacijentkinja, odnosno, zajednički aleli pojedinačnog nukleotidnog polimorfizma (engl. single nucleotide polymorphism, SNP) PD-1L rs4143815 C/G su amplificirani tehnikom lančane polimerizacije (engl. polymerase chain reaction, PCR). U rezultatima ove studije dobijeno je da su najlošiji patološki odgovor imale pacijentkinje sa luminal A i luminal B tumorom dojke, dok su najbolji patološki odgovor imale sa pravim HER2 pozitivnim tumorom (p<0.001). PD-L1 ekspresija bila je više prisutna kod trostrukonegativnih i HER2 pozitivnih pacijentkinja u odnosu na druge molekularne tipove. Kompletan patološki odgovor češće su postizale pacijentkinje sa PD-L1 pozitivnim u odnosu na PD-L1 negativni karcinom dojke. Pacijentkinje sa CG heterozigotnim genotipom češće su bile HER2 podtipa, češće su bile PD-L1 pozitivne i imale značajno veći kompletan patološki odgovor (p<0,001). Rezultati ovog istraživanja ukazuju da je za trostrukonegativne tumore koji su statistički značajno PD-L1 pozitivni u odnosu na druge podtipove, ali nisu postizali značajan kompletan patološki odgovor neophodna neoadjuvantna terapija PD-L1 inhibitorima kao dodatak hemioterapiji. Dok za prave HER2 pozitivne tumore dojke koji su, takodje, statistički značajno PD-L1 pozitivni ima smisla buduća istraživanja usmjeriti u pravcu ordiniranja imunoterapije u neoadjuvantnom setingu kao dodatak dosadašnjoj standardnoj NAT- hemio i dualnoj HER2 blokadi.

Breast cancer is the most common malignant disease in the female population, accounting for about 24% of all malignancies in women. The cause of the disease is still unknown and we can only talk about risk factors such as early menarche, late menopause, infertility, taking oral contraceptives, obesity, smoking, physical inactivity. Genetically caused breast cancer occurs in about 10% of cases and is linked to mutations in genes such as BRCA1, BRCA2, PTEN, TP53, MLH1, MSH2, ATM, CHEK2, PALB. When it comes to the treatment of early breast cancer, surgery, adjuvant therapy, radiation therapy are available. In recent years, chemotherapy (neoadjuvant chemotherapy-NAT) is first prescribed for early breast cancer, especially HER2-positive and triple-negative, and then surgery is planned. The measure of response to NAT is the pathological complete response (pCR). The pathological response has predictive and prognostic significance and correlates with the time until the return of the disease (progression free survival-PFS) and overall survival (overall survival-OS). Apart from the standard predictive and prognostic factors that classify breast cancer into molecular subtypes (ER status, PR receptor status, HER2 status and Ki 67), recent research is focused on examining the expression level of PD-L1 in breast cancer as a potential target for immunotherapy. The aim of this doctoral dissertation was to examine the degree of pathological response after NAT in different molecular subtypes of breast cancer, to examine PD-L1 expression as well as PD-L1 gene polymorphism in different molecular subtypes, as well as the relationship between molecular subtype, tumor pathological response, PD-L1 expression and polymorphism of the PD-L1 gene. This study included 170 patients with early breast cancer who underwent needle biopsy of the tumor and underwent NAT and then surgery. In addition to the standard parameters of the molecular subtype (ER, PR, HER2, Ki 67), immunohistochemistry of PD-L1 status was performed on the biopsy samples, which was evaluated using the SP142 antibody on the Ventana apparatus. On the other hand, the PD-L1 gene polymorphism was determined from the patient's blood, i.e., the common alleles of the single nucleotide polymorphism (SNP) PD-1L rs4143815 C/G were amplified using the polymerase chain reaction (PCR) technique ). The results of this study showed that patients with luminal A and luminal B breast tumors had the worst pathological response, while patients with true HER2 positive tumors had the best pathological response (p<0.001). PD-L1 expression was more present in triple-negative and HER2-positive patients compared to other molecular types. A complete pathological response was more often achieved by patients with PD-L1 positive compared to PD-L1 negative breast cancer. Patients with CG heterozygous genotype were more often of HER2 subtype, were more often PD-L1 positive and had a significantly higher complete pathological response (p<0.001). The results of this research indicate that for triple-negative tumors that are statistically significantly PD-L1 positive compared to other subtypes, but did not achieve a significant complete pathological response, neoadjuvant therapy with PD-L1 inhibitors is necessary in addition to chemotherapy. While for true HER2 positive breast tumors that are also statistically significantly PD-L1 positive, it makes sense to direct future research in the direction of prescribing immunotherapy in the neoadjuvant setting as an addition to the current standard NAT-chemo and dual HER2 blockade.