Plerixafor augments PBSC collection, but the optimal approach for incorporating it into mobilization is uncertain. Forty-nine consecutive patients mobilized with G-CSF alone were analyzed, and a day 4 peripheral blood CD34 þ cell count of 0.015/ml was found to predict for a day 5 apheresis yield of 2 Â 10 6 CD34 þ progenitors/kg, our institutional minimum necessary for a single autologous transplant. On the basis of this relationship, a clinical guideline was developed which recommended pre-emptive use of plerixafor if the day 4 peripheral blood CD34 þ cell count was between 0.005 and 0.015/ml. A total of 166 consecutive subjects with lymphoma or plasma cell dyscrasias underwent G-CSF mobilization after adoption of this care pathway, and the mobilization failure rate was only 7% in patients managed per guideline. The median PBSC yield was 6.3 Â 10 6 CD34 þ progenitors/kg with G-CSF (day 4 peripheral blood CD34 þ cell40.015/ml) and 4.9 Â 10 6 CD34 þ progenitors/kg with G-CSF þ plerixafor (day 4 peripheral blood CD34 þ cell 0.005-0.015/ml). The median number of days of apheresis was 2 in both groups. This clinical guideline is an effective mobilization algorithm that minimizes mobilization failures, reduces poor apheresis yields, does not require risk factor identification and is simple to implement.

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Patients with post-allogeneic HSCT disease relapse can be treated with salvage chemotherapy but are also candidates for immune suppression withdrawal and/or donor lymphocyte infusion (DLI). A total of 237 adult patients experienced relapse of disease post-allogeneic transplant at our institution between 1995 and 2010. A retrospective institutional analysis was performed on the 52 patients who received DLI in that timeframe. The DLI product infusion doses ranged from 0.07 to 4.0 x 10 8 CD3+ cells. CML patients had the most favorable DLI response rates with 78% (n 5 7) in remission at 3 years. Patients with relapsed AML/ MDS and lymphoid malignancies fared worse with 36% and 21% OS at 3 years respectively. OS was superior in patients in CR prior to DLI (45%) compared to those with active disease (5%) and for patients under the age of 50 (32% vs 21%). Three year OS was observed of 5% for patients who relapsed prior to day +100, 29% for relapse between day +100 and 1 year, and 59% for relapse after 1 year. Patients who developed GvHD prior to relapse had a 3 year OS of 35% vs 9% in patients without GvHD. Patients with post-DLI GvHD had a 39% OS vs 11% for patients without GvHD after DLI. No difference in post-DLI survival was noted with regards to pre-transplant disease status, cell dose or transplant conditioning. CML patients respond well to DLI however in the TKI era, transplants for these patients are reserved for patients with TKI-resistant disease. In other patients, immune suppression withdrawal and DLI have limited efficacy for those who do not achieve CR post-relapse or who relapse within 3 months of transplant. These patients are in need of alternative treatment strategies.

Axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) are both anti-CD19 chimeric antigen receptor (CAR) T-cell therapies indicated for the management (mgmt) of relapsed/ refractory large B-cell non-Hodgkin lymphoma (B-NHL). Though two registrational phase 2 trials yielded promising results, comparison studies are lacking and long term data are not yet available. Given the approval of axi-cel in 10/2017 and tisa-cel in 5/2018, we conducted a survey in 7/2018 to better understand early prescribing patterns and mgmt strategies with these two commercial products in B-NHL. Surveys were issued to 26 US centers certified to prescribe both drugs, with 19 (73%) surveys returned. Of respondents, 26% took part in axi-cel trials, 26% in tisa-cel trials, 26% did not take part in either, and 21% took part in trials with both drugs. Tisa-cel was most frequently delivered in a hybrid setting (outpatient (outpt) chemotherapy and inpatient (inpt) CAR T infusion) in 42% of sites, 37% performed exclusively inpt treatment (tx), 11% outpt tx, and 11% used multiple tx strategies. Axi-cel was administered exclusively inpt in 47% of sites, 42% used a hybrid approach, and 11% used multiple tx strategies; however, no site employed entirely outpt axi-cel tx. There was significant variability in supportive care measures across sites. In grading toxicities, 32% of centers used Lee criteria, 32% CAR-T associated Toxicity (CARTOX) criteria, 21% center specific policies, and 16% company guidance. Similarly, toxicity mgmt varied greatly, where 42% of sites used center specific policies, 21% Lee criteria, 21% company guidance, and 16% CARTOX. In 68% of respondents, baseline patient (pt) factors impacted prescribing patterns. Tisa-cel was more likely to be considered in pts with advanced age/comorbidities or a history of central nervous system B-NHL/other neurologic conditions. In 84% of sites, product logistics influenced prescribing practice. The most frequently cited reasons were shorter production time favoring use of axi-cel followed by later onset of cytokine release syndrome favoring use of tisa-cel. Of respondents, the single strongest reason influencing tx decisions was drug toxicity profile (32%). The results of this survey highlight the significant heterogeneity in practice patterns that exist among sites offering both products in B-NHL. While numerous factors may impact prescribing patterns, toxicity profile and production time appear to heavily influence this decision. Given the limited available data and the relatively small number of pts treated with commercial drug at each site, open discussions about institutional experiences will be important in understanding the pros and cons of various approaches and products. Future efforts should focus on formulating consensus guidelines to standardize prescribing patterns and supportive care measures, with the goal of optimizing outcomes.

Background: Guidelines from the NMDP and ASBMT recommend allogeneic donor mobilization with 4-5 days of G-CSF followed by peripheral blood stem cell (PBSC) collection beginning the 5 th day. While our institutional standard has been 5-day mobilization and collection, given observations that some autologous transplant patients are adequately mobilized by day 4, and due to concern that a subset of allogeneic donors may be maximally mobilized earlier than day 5, we performed a feasibility study evaluating day 4 collection of allogeneic PBSC. Methods: Beginning 7/1/2013, HLA-matched sibling donors were collected on day 4 after G-CSF if the peripheral blood (PB) CD34 count was 0.04x10 6 /ml. Collected PBSC were held overnight at 4⁰C until transplant. Donors with day 4 PB CD34 counts of 0.04x10 6 /ml were collected on day 5, and those with inadequate CD34 cells/kg recipient weight in the PBSC product underwent repeat collection over two days. Results: 38 patients with matched-sibling donors were eligible for inclusion in the study, with a median follow-up of 217 days (range 45-458). Of 38 donors evaluated, 22 (57.9%) had a PB CD34 count 0.04x10 6 /ml on day 4. Eighteen of the 22 (81.8%) were adequately collected on day 4; 3 required 2day PBSC collections on days 4 and 5. One donor with an adequate PB CD34 count was collected on day 5 due to line issues. Of the 16 donors with a PB CD34 count <0.04x10 6 /ml, 7 underwent single day collection on day 5, and 9 required two-day collections. Of all donors eligible for inclusion, 18 (47.4%) were adequately collected on day 4, 8 (21.1%) were collected on day 5, and 31.6% required two-day collections. There was no significant difference in the median time to ANC and platelet engraftment based on day of PBSC collection.Conclusions: In our pilot study of HLA-matched sibling donors undergoing G-CSF mobilized PBSC collection, we found that 47.4% of donors were adequately mobilized to allow for a single PBSC collection on day 4. Using a PB CD34 cell threshold of 0.04x10 6 /ml on day 4 identified donors with high likelihood of adequate PBSC collection (81.8%). Our preliminary data suggest day 4 may be the optimal day of collection for a population of healthy donors, reducing donor G-CSF exposure leading to enhanced safety for donor and recipient, and expected cost savings. Ongoing analyses include financial and resource utilization review, detailed comparison of day 4 versus 5 PBSC product composition, and matched cohort analysis of day 4 versus 5 collection and correlation with transplant outcomes.