High Frequency of Identical Lymphoma Clones Detected in Pre-Treatment Tumor and Plasma from Untreated Patients with HIV-Associated Lymphomas: Prospective Multicenter Trial of the AIDS Malignancy Consortium (AMC 064)

Background: Individuals with HIV are at increased risk for B cell lymphoid malignancy. We previously presented evidence from a single institution study that rearranged immunoglobulin (Ig) DNA could frequently be detected by clone specific PCR in HIV patients (pts) with lymphoma (Blood 2011;117:4860-2). To confirm and extend our results, we studied diagnostic tumor biopsies and plasma from untreated HIV patients with newly diagnosed lymphoid malignancy.

Methods:Paired diagnostic tissue and plasma samples from 49 patients with lymphoid malignancies were prospectively collected under Protocol AMC-064 (Clinicaltrials.gov NCT00981097). Using the LymphoSIGHT™ method, we amplified Ig heavy chain (IGH) variable, diversity, and joining and Ig kappa chain (IGK) gene segments from genomic DNA using universal primer sets. Amplified products were sequenced and analyzed using standardized algorithms for clonotype determination. Tumor-specific clonotypes were identified for each pt based on their high-frequency within the B-cell repertoire in the lymph node (LN) bx sample. When a high frequency clonotype was identified, we characterized this sample as "clonal Ig DNA". The presence of the tumor-specific clonotype was then quantitated in plasma samples. Pathologic and clinical data, including histology, Ki67 index, and International Prognostic Index (IPI) score, were collected.

Results:49 pts, including 27 DLBCL, 7 Burkitt, 7 Hodgkin, 5 plasmablastic, 1 primary effusion, and 2 "other', were enrolled. The source of tumor included FFPE (32), frozen tissue (3), unstained slides (9), and punch biopsy (1). Plasma was available from 48 pts. Lymphoma clones were identified in 41/49 (84%) patients based on their high frequency in the B-cell repertoire. The clonal Ig DNA identification rate in FFPE samples was 75% (24/32 patients) compared with 86% (24/28 patients) in which there was sufficient input DNA (≥ 15 ng). The clonal Ig DNA identification rate in slides was 78% (7/9 patients) and in frozen tissue was 67% (2/3 patients). 13 pts had 1 tumor specific clonotype, 11 had 2, 7 had 3, 7 had 4, 2 had 5, 1 had 6, and 8 had no identifiable clonotype. We observed 21 IGH-VDJ, 24 IGH-DJ, and 55 IGK receptor gene rearrangements. 5/7 (71%) of the Hodgkin pts had clonal Ig DNA. The lymphoma clonotype was detected in the plasma in 31/33 (94%) patients with clonal Ig DNA in their baseline tumor specimen. Quantitative analysis of the level of lymphoma clonotype ranged from 4.8 to 363,200 (median 11,725) lymphoma molecules per million diploid genomes in plasma at diagnosis. Clonal Ig DNA was identified in 24/48 plasma samples collected at diagnosis (50%). Patients with clonal Ig DNA in the plasma were more likely to have IPI score 3-4 (p = 0.039, two-tailed Fisher test).

Conclusions: Clonal Ig DNA is frequently present in baseline plasma in patients with HIV lymphoma including Hodgkin lymphoma. Sequencing for lymphoma clonotypes in the plasma may be a valuable addition in patients when tumor biopsy is challenging. Further exploration is merited to evaluate circulating lymphoma clonotypes as a surveillance and treatment monitoring approach.