Since the recent introduction of targeted therapies (i.e. the B-cell receptor inhibitor ibrutinib and the anti-BCL2 venetoclax), deep changes have occurred in chronic lymphocytic leukemia (CLL) patients'clinical management. Current guidelines recommend that chemoimmunotherapy is limited to patients with mutated variable region of heavy chain immunoglobulin (IGHV) genes and devoid of TP53 gene deletion/mutation, making mandatory the assessment of these biomarkers when patients require treatment. International guidelines for the analysis and reporting of IGHV and TP53 mutations have been established; TP53 mutations are reported if clonal, i.e. identified by Sanger sequencing or with a variant-allele frequency (VAF) above 10% when analyzed by next-generation sequencing (NGS).
From January 2019 to December 2020, a network of 8 Italian certified laboratories, including ours, has been established, with the aim of providing the analysis of TP53 and IGHV gene mutations to all the Italian hematologists managing CLL patients in first disease progression: 678 patients from 45 Italian centers were evaluated.
The present project consists in the retrospective and prospective collection of clinico-biologic data from all the patients analyzed, as well as the re-testing by NGS in our laboratory of those samples resulted TP53 wild-type by Sanger sequencing, in order to address the following unanswered questions: 1) do the Italian hematologists adhere to the current guidelines that have changed the clinical practice in CLL and know on the application of the molecular predictive biomarkers? 2) do the prognostic scores established mostly in the setting of relapsed/refractory patients under novel drugs (i.e. SRSi, 4-factor score) maintain their value in the first-line setting? 3) do clonal and subclonal TP53 mutations impact on the efficacy of first-line targeted therapies? The final aim is the optimization of the personalized approach for CLL patients outside clinical trials.
Innovation.
The innovation of the present project relies on: i) the experimental approaches (i.e. next generation sequencing) for the identification of subclonal TP53 mutations of potential clinical impact in the era of novel targeted therapies (i.e. "chemo-free" treatment) in CLL; ii) the effort of making closer biologic data provided from certified laboratories to the daily practice of Italian clinicians outside of clinical trials.
Advancements respect to the state of the art.
It is currently unknown the adherence of Italian hematologists to the current guidelines that have changed the clinical practice and regulated the therapeutic choices in CLL. It is unknown their knowledge on the application of the molecular predictive biomarkers. It is unclear if the prognostic scores established and validated mostly in the setting of R/R patients under novel drugs maintain their value in the first-line setting. Finally, it is unclear whether and how clonal and subclonal TP53 mutations impact the efficacy of first-line therapies (chemoimmunotherapy or novel drugs). The present project should provide all these information.
Expected results and impact
The expected results achieved from this project are the following:
1) definition of educational needs in the Italian hematology community;
2) definition of laboratory needs, i.e. establish a network of Italian referral laboratories for CLL;
3) confirm the prognostic value of the proposed prognostic scores even for previously untreated CLL patients receiving novel drugs as first line treatment;
4) define the clinical significance of subclonal TP53 mutations in the era of novel drugs.
Thus, the project "in toto" (point 1 to 4) has clinical implications that could contribute to improve the present and future management of CLL patients, leading to an always more personalized and "chemo-free" approach: i.e. identify the patients that will benefit the most from the novel drugs (ibrutinib, venetoclax) respect to those (i.e. high-risk prognostic scores; TP53 del-mut) that will need experimental approaches with innovative combinations or novel BTK/BCR inhibitors, with the final aim of prolonging patients'survival and quality of life.
From a scientific point of view (point 3), it is important to understand if subclonal TP53 mutations have a clinical relevance and influence the disease course in the era of novel drugs and if the 10% VAF cut-off proposed from the current guidelines for clinical reporting (Malcikova et al, 2018) has to be modified or not.
The project has also socio-economic implication: the expected results of points 1) and 2) could open the way to an optimization of Italian laboratory network and hematologists' education, that will reduce the burden and costs on the national health system.
CLL median age at diagnosis is 65-70 years; since the prevalence of CLL increases with the increasing of the general population age, this aspect is particularly relevant in Italy, where the population life expectancy is one of the longest in the world and the number of elderly is increasingly high. Therefore, a personalized patient's management and treatment are mandatory to balance costs and benefits.
In a novel era of "chemo-free" approaches for CLL patients, it is crucial to follow the current biomarkers that guide the therapeutic choices and also to identify novel clinico-biologic markers that can influence positively or negatively the efficacy of a given treatment.
Future developments
In CLL, whilst it is now clear when to adopt chemoimmunotherapy or targeted therapies in the context of TN or R/R patients, it is unclear whether there are biomarkers, beside clinical parameters, that can predict upfront patients with different outcomes after a given targeted therapy i.e. ibrutinib-based vs venetoclax-based vs combinations (i.e. venetoclax+ibrutinib), etc.
Considering also the upcoming novel drugs such as second generation BCR inhibitors and double or triple novel combinations that will further modify the therapeutic armamentarium for CLL patients, it would be very useful to have reliable clinico-biologic scores to optimize the treatment choices. The results produced by the present project could contribute to these developments.