mia Nicholas Chiorazzi The Feinstein Ins3tute for Medical Research - - PowerPoint PPT Presentation

A Some mewhat Diffferent View of the the Gene ne3c 3c Portr rtrait ait

• f Chronic Lymp

mphocy3c Leukemi mia

Nicholas Chiorazzi

The Feinstein Ins3tute for Medical Research Northwell Health Manhasset, NY

Acknowledgments

Davide Bagnara Stefano Vergani Andrea Mazzarello Gerardo Ferrer Anthony Liew

UNIVERSITÀ DEGLI STUDI DI GENOVA

Te Tenets

§ In general, the human genome is evolu2onarily designed to correct soma2c muta2ons that might occur § Cancer is a disease in which these protec2ve mechanisms ul2mately fail, resul2ng in gene2c derangements of specific, biologically important genes § CLL is the same in some ways and different in others. § B lymphocytes, the cells that become leukemic in CLL, need to deal with a different evolu2onarily design, i.e., the desired accumula2on of muta2ons in the genes coding for the an2gen-binding regions of an IG molecule by ac2va2on- induced deaminase (AID)

IG V-region gene mu muta3ons in CLL

§ Soma2c muta2ons of IGHV genes divide CLL clones/ pa2ents into two categories: U-CLL and M-CLL § U-CLL and M-CLL pa2ents differ in their clinical courses § IGHV muta2on status remains an important and reliable indicator of clinical course and survival in CLL

§ Almost invariably “IGHV muta2on status” is fixed.

§ Very rarely does a clone “switch” from U-CLL to M-CLL, although this can occur

§ However, Sanger sequencing studies indicate that the IGHV-D-J rearrangement of CLL clones can undergo intraclonal heterogeneity, even U-CLL cells § AID, the gene responsible for IGHV-D-J muta2ons, is func2onally ac2ve in CLL. § If inten2onally upregulated, this enzyme will mutate CLL V regions, even in U-CLL cells.

(Gurrieri et al. 2002; Bagnara et al. 2006; Volkheimer et al. 2007; SuSon et al. 2015)

Ques3ons:

§ How extensive is the ongoing IGHV-D-J muta2on process in CLL? § Can this ongoing process be used to predict the likelihood that muta2ons, at least those caused by AID, will occur at sites throughout the genome and thereby possibly lead to clinical progression? § Can the IGHV-D-J sequences of the remaining non-CLL CD5+ B lymphocytes provide clues to the development of CLL from normal B cells?

Approach:

§ Sort all CD5+ cells from CLL pa2ent’s blood. This should yield the CLL clone, its intraclonal variants, and any normal CD5+ B cells leY in the blood § Perform high-throughput “deep” sequencing of the IGHV-D-J repertoire of FACS sorted CD19+CD5+ from 39 untreated CLL pa2ents § Analyze data using appropriate bioinforma2c tools

CLL clone

Whole CD5+ B cell repertoire

CLL clone CLL sub-clones

Whole CD5+ B cell repertoire

CLL sub-clones developing through intraclonal diversifica2on can be significantly expanded

CLL with most expanded sub-clone at > 1% 60% (n = 30)

CLL sub-clones

50 100 150 200 250 50 100

TFT (months) % untreated > 1% < 1%

p=0.01

mline

mline

• nly

M-CLL

CLL clones have evolved from precursors differing in IGHV muta2onal load

n=1 6

n=3

mline mline

Clinically relevant CLL clone Inferred Germline M- and U-CLL

CLL clone CLL sub-clones

Whole CD5+ B cell repertoire

The CD19+CD5+ compartment in CLL pa2ents contains leukemic and non-leukemic B-cell clones

CLL with non-leukemic VDJ sequences > 0.75% 45% (n = 22)

50 100 150 200 250 50 100

TFT (months) % untreated > 0.75% < 0.75%

p=0.02

Whole CD5+ B cell repertoire

CLL clone

CLL clone CLL clone CLL sub-clones

Whole CD5+ B cell repertoire

CD19+CD5+ B-cell popula2on can present an a second MBL-like clonal expansion

Whole CD5+ B cell repertoire

CLL clone

CLL with most expanded non-CLL clone at > 1% 24% (n = 12)

Rela2ve fitness

1 100 1000 10 500

cells/ul

high-count MBL 19% (n=6) low-count MBL 42% (n=12)

Absolute fitness

CLL clone CLL clone Non-leukemic clones CLL sub-clones

Whole CD5+ B cell repertoire

CD19+CD5+ non-leukemic B-cell popula2on can be oligoclonally expanded

CLL with 3 clones cons2tu2ng > 50% of the non-leukemic sequences 67% (n = 31)

Non-leukemic clones

CLL present stereotyped IGHV-D-J sequences

(Agathangelidis et al. Blood, 2012)

CLL-like stereotyped IGHV-D-J sequences can oYen be found among the non-leukemic clones in the CD19+CD5+ compartment

CLL

Leukemic clone Non leukemic clones

CLL major subsets 1 1 2 1 3 1 4 201 5 2 2 6 1 2 (x7), 3, 5, 14 (x2), 64B (x2) 7 2 8 64B 9 1 (x5), 8 (IgG, UM) 10 4 (IgG, M), 64B

(Agathangelidis et al. Blood, 2012)

CLL samples (n=50)

Samples with stereotyped CLL clone (n=6) 12% Sample with stereotyped non-leukemic Clones (n=6) 12% (n=2)

0.00 0.03 0.06 0.09 0.12 Non−CLL clones Memory Memory−IgD Naive Transitional

% of stereotyped clones

Non-leukemic clones

Implica2ons

In > 80% of M-CLL pa2ents, IGHV-D-J sequence with lower muta2on load can be detected The leukemogenic process might start in a cell with less IGHV soma2c muta2ons

Implica2ons

• Non-leukemic CD5+ B cells can display MBL-like oligoclonal expansion and CLL

stereotypes

• MBL-like oligoclonal origin of CLL
• Genomic muta2onal events can occur at two stages of B-cell matura2on:
• prior to IGHV-D-J recombina3on: ini2a2ng muta2on.

(contribu2on of inherited factors?)

• a`er IGHV-D-J recombina3on: final leukemogenic muta2on
• Do not recapitulate typical CLL VH genes usage and HCDR3 length distribu2on
• The final leukemogenic hint involve a further BCR selec2on

Implica2ons

IGHV-D-J repertoire of CD5+ B cells can be clinically relevant:

• Expanded CLL subclones might be a proxy of AID off-target muta2ons ac2vity

and thereby indicate the poten2al genera2on of aggressive sub-clonal variants

• Abundance of CD5+ non-leukemic sequences directly correlates with bemer
• utcome

Acknowledgments

Davide Bagnara Stefano Vergani Andrea Mazzarello Gerardo Ferrer Anthony Liew

UNIVERSITÀ DEGLI STUDI DI GENOVA

CD19+CD5+ non-leukemic B-cell popula2on can be oligoclonally expanded

Most expanded clone > 25% of the non-leukemic sequences 65% (n = 30)

Non-leukemic clones

CD19+CD5+ non-leukemic B-cell popula2on can be oligoclonally expanded

Non-leukemic clones

CLL IgM controls

0.00 0.05 0.10

HCDR3 aa length Frequency

Mutated sequences Un−Mutated sequences

non−leukemic CD5+ clones

Non-leukemic clones in the CD19+CD5+ compartment do not present VH genes usage and HCDR3 length distribu2on typical of CLL

Mutated Sequences Un−Mutated Sequences I G H V 1 − 6 9 I G H V 3 − 2 3 I G H V 4 − 3 4 I G H V 1 − 6 9 I G H V 3 − 2 3 I G H V 4 − 3 4 0.00 0.05 0.10 0.15 0.20 0.25

VH genes Frequency

Mutated Sequences Un−Mutated Sequences I G H V 1 − 6 9 I G H V 3 − 2 3 I G H V 4 − 3 4 I G H V 1 − 6 9 I G H V 3 − 2 3 I G H V 4 − 3 4 0.00 0.05 0.10 0.15 0.20 0.25

VH genes Frequency

SUBSET

CLL IgM controls non−leukemic CD5+ clones