GTXI Gtx, Inc.

On October 3, 2019, the Company announced that it has opened for enrollment a Phase 1b expansion cohort of its Phase 1/2 clinical trial of cirmtuzumab, a Receptor tyrosine kinase-like Orphan Receptor 1 (“ROR1”) targeted monoclonal antibody, combined with ibrutinib, in patients with mantle cell lymphoma (“MCL”). The decision to open an expansion cohort in MCL of the ongoing Phase 1/2 CIRLL (Cirmtuzumab and Ibrutinib targeting ROR1 for Leukemia and Lymphoma) clinical trial was based on favorable interim results from the dose-finding cohort of the trial, including that the combination was well-tolerated and that complete responses were observed in two heavily pre-treated patients who had received and failed multiple chemotherapy regimens and an autologous transplant, as well as either an allotransplant or chimeric antigen receptor T cell (“CAR-T”) therapy, prior to participating in this clinical trial.

In June 2019, the Company presented interim data at the American Society of Clinical Oncology (“ASCO”) annual meeting, including the preliminary results from the first six patients with MCL treated in the CIRLL clinical trial. One patient with MCL, who had relapsed following an allogeneic stem cell transplant, experienced a confirmed complete response (“CR”) after 3 months of cirmtuzumab plus ibrutinib treatment, including complete resolution of a large mediastinal mass. This CR appears to be sustained and has been confirmed to be ongoing after completing 12 months of cirmtuzumab plus ibrutinib treatment. Following ASCO, a second confirmed CR occurred in a patient who had progressive disease after failing several different chemotherapy regimens, autologous transplant and CAR-T therapy. Additional data from this clinical trial will be presented at a future medical conference.

The CIRLL clinical trial is supported by a grant from the California Institute for Regenerative Medicine (CIRM) and is being conducted in collaboration with the University of California San Diego (UCSD).

Cautionary Note Regarding Forward-Looking Statements

The Company cautions you that statements included in this report that are not a description of historical facts are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplates,” “believes,” “estimates,” “predicts,” “potential” or “continue” or the negatives of these terms or other similar expressions. These statements are based on the Company’s current beliefs and expectations. Forward looking statements include statements regarding: the Company’s plans to present additional data from its ongoing Phase 1/2 clinical trial of cirmtuzumab; the expectation that the Company will be able to enroll patients into the Phase 1b expansion cohort; and the Company’s belief that favorable outcomes from the ongoing Phase 1 portion of the clinical trial support opening the Phase 1b portion. The inclusion of forward-looking statements should not be regarded as a representation by the Company that any of its plans will be achieved. Actual results may differ from those set forth in this release due to the risks and uncertainties inherent in the Company’s business, including, without limitation: uncertainties associated with the clinical development and process for obtaining regulatory approval of cirmtuzumab and the Company’s other product candidates, including potential delays in the commencement, enrollment and completion of clinical

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trials; the Company’s dependence on the success of cirmtuzumab and its other product development programs; the risk that interim results of a clinical trial do not necessarily predict final results and that one or more of the clinical outcomes may materially change as patient enrollment continues, following more comprehensive reviews of the data, and as more patient data become available; the risk that unforeseen adverse reactions or side effects may occur in the course of developing and testing product candidates such as cirmtuzumab and the Company’s other product candidates; the Company’s limited operating history and that fact that it has incurred significant losses, and expects to continue to incur significant losses for the foreseeable future; risks related to the inability of the Company to obtain sufficient additional capital to continue to advance the development of cirmtuzumab and its other product candidates; and other risks described in the Company’s prior reports as well as in public periodic filings with the U.S. Securities & Exchange Commission. All forward-looking statements in this report are current only as of the date hereof and, except as required by applicable law, the Company undertakes no obligation to revise or update any forward-looking statement, or to make any other forward-looking statements, whether as a result of new information, future events or otherwise. All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.