T-cell lymphomas have remained treatment-challenging, not least because of their remarkable heterogeneity. The lab of Robert Orlovsky (co-founder of Asylia) analyzed the membrane proteome of peripheraland cutaneous T-cell lymphoma and discovered that surface Heat shock protein (csHSP)-70 as being consistently overexpressed. While HSP70 is well established as an intracellular stress-response chaperone, itslocalization to the cell surface in cancer, is gaining increased attention. Considering the recent clinical successesof antibody-drug conjugates and the exceptionally high and selective overexpression of cell surface HSP70 inT-cell lymphoma, we summarize that csHSP70 presents as an exceptionally attractive target for antibody drugconjugates (ADC) for the treatment of this malignancy. We have generated a high affinity monoclonal antibody(clone 239-87) specifically recognizing cell-surface HSP70. In preliminary data, we have generated an ADC ofmAb 239-87 with MMAE, which specifically bound csHSP70 on T-cell NHL cell lines but did not bind normalperipheral blood-derived cells. Linked to MMAE, the 239-87-MMAE ADC showed cytotoxic activity against bothperipheral and cutaneous T-cell lymphoma lines cell lines with comparable, or greater potency than the leadingclinical ADC, brentuximab vedotin. We now propose a series of critical experiments to accelerate the clinical translation of 239-87 ADCs forthe treatment of T-cell lymphoma. In aim 1, we will humanize mAb 239-87 and optimize the drug-likecharacteristics of the current murine clone. We will study binding of the leads to soluble HSP70, and to csHSP70in wild-type and genome edited cell models to verify that they retain csHSP70 affinity and specificity. In specificaim 2, we will convert clone 239-87 mAb into an ADC. We will first synthesize a panel of ADCs based on theoptimal lead antibody molecule linked to MMAE, a maytansine, a camptothecin, and a pyrrolobenzodiazepinewith cathepsin- and acid-cleavable linkers and compare their efficacy against T-cell lymphoma cell lines. Next,we will genetically modulate csHSP70 and perform internalization and quantitative flow studies to determine theminimum csHSP70 expression needed to see anti-cancer efficacy. Finally, we will verify the potential for synergybetween our ADCs and agents that enhance csHSP70, such as histione deacetylase inhibitors. In Aim 3, we willvalidate the activity of clone 239-87 ADCs using in vivo tumor cell line-derived models. Next, we will validate theactivity of selected best performers in more physiologically relevant patient-derived xenograft (PDX) models.Finally, we will perform pharmacokinetic studies in these PDXs to begin to understand potential drug distributionand toxicity parameters. Taken together, these studies will provide a proof-of-concept that HSP70-targeted ADCs have thenecessary efficacy and pharmacologic properties for development as attractive drug candidates and allow us tomove forward with investigational new drug-enabling toxicology studies in preparation for phase I clinical testing.
Public Health Relevance Statement: NARRATIVE
We have identified cell surface HSP70 as a novel prominent tumor antigen in diverse neoplasms, including
treatment-recalcitrant T-cell lymphoma. We have developed a high affinity mouse monoclonal antibody, 239-87,
against cell surface HSP70, whose high expression in T-cell lymphoma makes it an attractive candidate for
antibody-drug conjugation targeting. Here, we now propose to generate antibody drug conjugates of clone 239-
87 and to undertake several key development steps for clinical translation, including humanization, validating
the mode-of-action and evaluating the pre-clinical anti-neoplastic efficacy.
Project Terms: <20-(S)-camptothecine><22-secocamptothecin-21-oic acid lactone 21><70-kD Heat-Shock Protein> | | | | | | | | | 